# Seoul P4 initial Evaluation- Production LEDs



## NewBie (Dec 29, 2006)

Well, I got home less than an hour ago, and just as I'd been hoping for, my first production Seoul P4 LEDs had arrived.

I know these are a hot item for many, so without any delays, lets get some photographs.


Photographing these was a real pain, as the very, very soft gummy bear surface acts like a powerful dust magnet. I'd clean it, get it set up for a photograph, and it would have new dust specks on it, so after three tries, I finally gave up. Unfortunately, I don't have a laminar flow bench to give me filtered air.

These LEDs are rather cloudy, so I had to play a few tricks with lighting, to get an okay image.













Focused up off the die at the top of the phosphor, notice the tint variation across the die area:











I fitted one of these to a SO27XA, which isn't the smoothest reflector (I'll get it in a more perfect reflector later) which hides a number of the tint issues since the surface is rather distorted, but it was something that I could quickly get pictures of. Due to the tint variation of the image, and AWB, the camera tint kept changing slightly between shots:






















For the white wall crowd, I apologize, the camera doesn't render tint variations near as well as the human eye, but that is a common shortcomming of digital cameras. The distorted SO27XA did a decent job of mixing up the tint, so the distorted reflector actually helps. I'd **highly** recommend one of McGizmos textured reflectors. The "tintyness" of the beam is probably second only to the Nichia Jupiter and Nichia 5mm LEDs- but quite a bit better than the 5mm LEDs.


So, where does the tint variation within each beamshot come from? This image should help explain that, it is the bare emitter shinning on a piece of paper:






For fun, I used a high end camera lens to image the LED on a wall, and took a photo of it:






With some of the smooth reflectors, I could see artifacts of the bond wires on the wall, reminds me a little bit of the hotwires. I'll see if I can get a photo of it if I have time later. Again, I'd **highly** recommend one of McGizmos textured reflectors to help out with this!


Even though this LED uses the same CREE EZ1000 die as the CREE XR-E LED, the way the optics were done, it emits much more of it's light sideways, so you have a very substantial drop in flood brightness in a reflector. But, conversely, with so much more of the light going sideways, more of it is directed forward, so this will be great news for those folks who like burning bright hotspots which throw better. Unfortunately, if tint variations within your beam bother you, you'll need to use a textured reflector to hide them, which will cause the throw to suffer.

With an aspherical lens, with a much higher porportion of the light going sideways out of the P4, substantially less hits a given sized lens, so less will be directed forward, as compared to the CREE XR-E.

Another drawback of this LED is that the slug is shorted to the positive side, where nearly every flashlight has a negative body. If the heatsink spot isn't isolated with anodizing, you will need to come up with a method of isolating the slug (hurts thermal performance- unless you are clever), or risk blowing up your LED and also the flashlight converter.

Be careful with the dome lens on the Seoul P4, it is very easy to damage the very soft gummy dome.

I think we got **really majorly** spoiled with the Luxeons, which had very little if any tint variation at all within the LED. IMHO, the magic trick for the Seoul P4 is the rough textured McGizmo reflectors. With *plenty* of extra lumens as compared to the Luxeons, you can easily afford to use a rough reflector to blur the tints, IMHO- unless you need every single lumen possible in a tight spot. Personally, I prefer spots that fade, instead of sharply cutting off.

Anyhow, I've got more testing to go do...


Some tidbits from later points in the thread (plenty of other things to dig in the thread if you are interested):












The above graph has too much data on it to see clearly, so if you are interested, download the larger version:
http://www.molalla.net/~leeper/sp4int3.png


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## iNDiGLo (Dec 29, 2006)

Let me be the first to say thank you for this informative thread. I bet it took a long time to photograph and write everything up. 

Once again another first rate job. :goodjob:


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## EngrPaul (Dec 29, 2006)

I hope this means the beauties I bought won't be long behind...


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## Nitroz (Dec 29, 2006)

Nice evaluation as always! I think I will stick with the Cree XR-E.
THanks!


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## SuperTorch (Dec 29, 2006)

Great to know that it is throwing a lot more to the sides and that its now verified. The tint shifts don't look bad at all to me and with anything but a white wall would be hard to see. Next up is how many lumens max can you get out of them. Very Cool, Once again your picture skills are top notch and thanks for the info, when you name is on a post like this it means 300+ reponses. Can't wait for your furter analysis.


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## LITEmania (Dec 29, 2006)

Newbie : Thanks for review.

newbies ; FYI


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## CM (Dec 29, 2006)

Outstanding photos and write up. Any thoughts on brightness levels compared to the Cree's? In other words, did Seoul do the EZ1000 die any justice?


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## chimo (Dec 29, 2006)

Newbie, great photos and thanks for the quick review. Looking forward to the rest!

Paul


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## jtice (Dec 29, 2006)

Thanks alot for the photos and info newbie.

Im wonder the same as CM,
are they bright enough to warrant using over the Crees?
The Crees seem to have that odd halo effect in some reflectors, 
but they at least seem to have a good overal tint, and smoothness.

~John


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## fnmag (Dec 30, 2006)

Good info and great pics. Thanks.


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## McGizmo (Dec 30, 2006)

Nice macro work and write up Newbie! :thumbsup:

In terms of flux, I know one guy I respect who claims that Seoul is doing a better job than Cree in releasing the photons from the die and out beyond the phosphor conversion. As I stated in another thread, I don't know how we could ever know one way or the other unless there was a blatant disparity which so far doesn't seem to be the case.

The only data point I can add at present is I did compare a XR27 (DBx2-917) Cree P4 against a S27 (DBx2-917) Seoul P4 U flux in my integrating sphere and measured 119 lumens with the Cree and 133 lumens with the Seoul. A tested (at 68 lumen) 27LT sporting U bin LuxIII measured 70 lumens at this testing time. All three lights "present" to the integrating sphere in the same manner. One sample of each LED is no basis for comparison really but I will go out on a limb and suggest that Seoul isn't butchering the EZ1000 from what I have seen so far.

I have noticed that the color of the phosphor varies from LED to LED in the reel I have been working with which I find a bit surprising. Some reflectors give a gold image and others a light yellow image. The gummy bear seems to vary in clarity as well. :shrug:

I agree that there is plenty room for improvement on tint with these; both within the distribution of the single LED as well as consistency from one LED to the next. The Seoul P4 does give you plenty of reasonable if not flawless light output to work with and in a lambertian distribution which is better suited for many of the optics we have become familiar with.

To my way of thinking, the XR-E and Seoul P4 have some marked differences and depending on the application and desired distribution of light, one or the other may have a distinct advantage. I think the ease of use and retro fitting with the Seoul P4 will steal some of the XR-E's thunder at least initially but the XR-E has its own strength and qualities which will keep it well in the picture, IMHO.


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## yaesumofo (Dec 30, 2006)

Not exactly drop in replacements are they?
Newbie, What about lumen production? Vf''s? efficiency? Do these little suckers Rock or what?

Yaesumofo


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## kogatana581 (Dec 30, 2006)

I have seen a few comments such as those below that pique my curiosity.

_"...consistency of jelly with too little water. It seems the glass was held on with this stuff."

"...the very, very soft gummy bear surface"
_

Will this characteristic impair this LEDs reliability?


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## Raybo (Dec 30, 2006)

Thanks again NewBie!

And again!

Ray


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## McGizmo (Dec 30, 2006)

KT,

In an exposed environment, the Cree XR-E wins hands down, IMHO. Protected in the interior of a flashlight, the Seoul will do just fine. The first XR-E sample I had ended up loosing its lens from some rough bench treatment but Cree had caushioned that the lenses were not well retained. With the production parts, I would think that the shock required to make these LED's come apart would be of a level that would do significant damage to the host itself. :shrug:


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## SuperTorch (Dec 30, 2006)

Well for a quick toss in a none optimized reflector the hot spot and beam dispersion looks really good to me, I know tint shift is a issue(Small to me) but I like the looks of the throw in those shots even if it is early. If it only gets better then were really in a win/win situation. Cant wait for all my lights to be 150+ lumens.


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## SuperTorch (Dec 30, 2006)

LITEmania said:


> Newbie : Thanks for review.
> 
> newbies ; FYI


 
So the diameter of the Seoul W42180 is not the same as the Lux 3? In the group buy thread there seems to be different Seouls version and a Data sheet there shows one of the Seoul's as very very close to a Luxeon.


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## NewBie (Dec 30, 2006)

Sorry, I was gone, went to dinner it was great.

Kogatana581,

I can tell you that when you don't abuse the XR-E's dome during assembly, that they in fact do stay intact after extreme vibration, HALT testing, and crash shock testing.


Yaesumofo-

This sample of 1 so far, measures 3.758V @ 1 Amp at the emitter leads.

Lumens looks to be similar, but I will need to do fairly precise comparisions as they are close. This one is consuming a good amount more power than my reference CREE P3 I tested, about 0.378 Watts more, or 10% more.

As far as tint variation comparisions, I'll offer the following:

CREE XR-E:





Luxeon III (yes, it is actually on a curved surface, and the smooth tint output causes a lack of depth perception):






Seoul Semiconductor P4:






Don,

Your two parts you were comparing, your integrating sphere software (which also does spectral plots) indicates the CIE x and y co-ordinates, could you offer us the co-ordinates for the two you referenced for comparision?

Also, did you check the LED current during the test, I've noticed there is a decent amount of current set point variation in the GD converters.


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## Hellbore (Dec 30, 2006)

Where are you guys getting these Seoul P4 LED's from?

Newbie - Why are you so awesome?


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## Beamhead (Dec 30, 2006)

The SSC P4 seems angry blue?


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## McGizmo (Dec 30, 2006)

Newbie,
I have not had a means of calibrating my IS for color so beyond relative comparisons, I wouldn't put any credability to the numbers. I didn't look at them. The drivers used in the data point I offered were DBx2's and I would expect that there is some variation in them as well. No telling which was higher in current or if so, by how much. 

Lumileds is the winner on even tint in beam and I put Cree next up. Seoul has done better, IMHO,with the P4 than previous samples I have seen. It is what it is and whether it can be quantified in any reasonable fashion is an issue and concern for others. :shrug: 

In terms of flux, the core of the Seoul P4 is the EZ1000 and I have viewed enough of these in flashlights now and taken lux measurements and by and large, they do what one would expect them to do. I have an Aleph 3 DB917 and a HD45 917 both with P4's and both lights break the 10k lux barrier. I don't believe they could do that without some flux in the volume one would expect from the EZ1000.

As you have stated, the P4 is no star on a white wall.

I have lights using P4's that couldn't be improved upon, with current technology, by replacing the LED by another. I have lights using the XR-E that also couldn't be improved upon by replacing the LED by another. This is subjective opinion and not objective fact.


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## NewBie (Dec 30, 2006)

Here is another point of reference.






FYI, I rinsed off the Seoul P4 again, it keeps reaching out and grabbing dust out of the air... : ( 

If I decide to use many of these, I might think about making my own mini laminar flow bench, along with a +/- ion generator for equalizing charges to help keep the static down. Besides rinsing with water or isopropyl alcohol/water mix, anyone come across any great ideas on removing/preventing the dust collection on the Seoul P4?

My batteries started getting low on the flashlight on the right for the shot below, so the Luxeon III here has a bit less light, otherwise the extreme clarity of the Lux III in comparision to the Seoul P4 would have been quite obvious, but here it is anyhow:


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## SuperTorch (Dec 30, 2006)

Are there no type of clear coating/sprays that would stand the heat(not crack/yellow) once the led is on and at the same time offer a smoother and maybe different/protective cover as far as repelling dust/foreign matter, surely the great DuPont has something up their sleaves.


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## kogatana581 (Dec 30, 2006)

NewBie said:


> Here is another point of reference.
> 
> 
> 
> ...



My staff engineer provides the rest of us each an aerosol spray-paint cannister-sized aluminum can of compressed air to clean some of our tools such as flashlight lenses, googles, etc.

The Seoul LED looks like an unfinished project.


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## NewBie (Dec 30, 2006)

Unfortunately, with this sticky gummy dome, blasts of air don't help much, except stir the dust around the area, and the part yanks more dust out of the air.


Okay, this next section will be of concern to white wall hunters and Ring Wraiths.

Anyhow, I finally got one of the Seoul P4 emitters mounted on a post, so I could put it in a nice perfect and smooth MagLite reflector. I let the camera AWB, since due to the tints that come out at different exposure levels, I was getting some really wierd looking photos which made one look decent, but the rest looked like the set white balance was kaddywhompus.


First a series of photos at different exposures:





















Above, in the smooth "perfect" MagLite reflector, some of the issues of the P4 start to really stand out, like bond wires getting in the way, tints (which the camera barely picks up), and a very, very distinct ring.


I fiddled a bit with emitter placement and adjusted the focus spot a few mils, and instead of dark lines from the bond wires, you get the shiny distinct reflection of the gold bond wires shown below at 2 o'clock and 4 o'clock:












I wish my digital camera had the latitude to show the tints like the human eye sees them.


Like I said before, I'd **really** recommend rough surface reflectors with the Seoul P4, they should do a decent job smoothing out the tint variation in the LED, and hide the shadows/reflections of the bond wires. They should also fix the ring wraith problems, as evidenced by the same problem with the CREE XR-E, that McGizmo managed to smooth out with his rough reflectors for his products. I can't emphasize how much better these Seoul P4 look in the McGizmo reflector, and I'd very highly recommend McGizmo's outstanding reflectors for fixing these issues.

There are more than plenty enough extra lumens in the Seoul P4 to spread things out, blend them, cover/hide shadows/reflections, send the Ring Wraiths back to Mordor, and create a nice smooth hotspot transistion, and still walk all over a Luxeon III.


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## ICUDoc (Dec 30, 2006)

Hi Newbie- thanks for another great thread! Good photos, cogent comments- it's all good, as we say.
The translucent stroma of the Seoul is very surprising and a bit concerning- I am sure lumens are lost due to inefficient diffraction through the gel.
Also it will interfere with the ability of the LED to be focused, as the phosphor will no longer be the sole emitter, but will be joined by a hazy surrounding band of gel i.e. act as less of a point source.
That said, the high efficiency and output of the Cree die would seem to shine through (as it were!) in your beamshots, so perhaps the primary optic (being closer to acting Lambertian) makes up for this. 
The thing I like about it above the Cree XR-E is that it doesn't have a ruddy great metal ring blocking some of the light!
Thaks again- I look forward to playing with these....


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## NewBie (Dec 30, 2006)

I hauled out one of Don's (McGizmo) outstanding reflectors (a prized possession), the rough surface HD45 and got MUCH better results. All the artifacts disappeared (rings, lines, etc), and the tint and rings really blended better. All that is really left is a cold white hotspot which blends to a warm (yellowish) corona that gets warmer for a ways into the flood, then a cold white flood.

It reminds me of why this McGizmo reflector is such a prized possession!

While fiddling around with the various McGizmo reflectors I have, I noticed that different parabolic shapes cause different tint effect blend patterns, and some of them cause a "double image" flood.

Anyhow, I got to looking at the side emitted light color profile a little closer, pay attention to the banding and tints, and then look from one side of the photo to the other and notice how the tint changes (close-up):


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## chimo (Dec 30, 2006)

NewBie said:


> Okay, this next section will be of concern to white wall hunters and Ring Wraiths.





Thanks for the continued flow of info on this. 

Why do you suppose they went to the gummy domes - more suitable index of refraction or easier to manufacture?


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## jtr1962 (Dec 30, 2006)

NewBie said:


> Besides rinsing with water or isopropyl alcohol/water mix, anyone come across any great ideas on removing/preventing the dust collection on the Seoul P4?


There are several types of antistatic sprays for plastics available which might work although I haven't tried one yet. I found the problem very annoying when I was working with Seoul LEDs. I don't know why they can't use a polycarbonate lens like the Luxeon or a glass one like the Cree. That and the fact the slug is not isolated are both negatives to me.


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## Erasmus (Dec 30, 2006)

Good job NewBie!


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## EngrPaul (Dec 30, 2006)

NewBie, Thanks for your many pictures, including side profiles. They are very useful!


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## photorob (Dec 30, 2006)

I you were take the gummy bear off the top of the led would it be possible to just lay down some clear high temp epoxy instead. If there is such a thing as clear high temp epoxy.


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## NewBie (Dec 30, 2006)

I went back and manually tweaked on the LED flood profile photo to get it looking closer to what I see with my eyes, using my monitor and my wife's.


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## NewBie (Dec 30, 2006)

Well, I wasn't that satsified with the P4 tint photos, so I decided to re-take a braketed series of them. I found if I turned it down to 250mA (instead of 700mA), it wasn't as tinty looking in the photos for some reason. Maybe the sheer brightness range in the photos was messing up the camera or something. Anyhow, these are closer in some ways to what I see:


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## McGizmo (Dec 30, 2006)

Newbie,

If you pair up your big aspherical lens with the Seoul and compare it to the Cree XR-E, Seoul P4 and a Luxeon, I think you can see the differences in the light images we are working with. Although the EZ1000 die is smaller than the Luxeon, in both the case of the XR-E and P4, there is diffusion and probably refraction and even some diffraction occuring as the light travels through the silicone and on out. More so I think than in the case of the Luxeon and as a result you are also projecting the "ghost" of the domes themselves. The effective spot diameter of the P4 is larger than that of the XR-E due in part I think to this and larger than that of the Luxeon as well. Even with a specular reflector, the edge of the spot is softer with the P4 compared to the XR-E or Luxeon. I would guess that this is also due in part to the phosphor in the P4 that extends past the die itself.

With some lenses and a specular reflector, I have seen the bond wire cat whiskers but it doesn't take much of an orange peel to remove these.

Had the K2 amounted to much more than a curiousity, I think the gummy bear's affinity to be surrounded by dust bunnies would have been a well addressed topic of discussion here.

I see your Luxeon sample has some of the separation of its goo. I had a X bin that had a large "bubble" in it and kept from using it in any builds because it was clearly obvious to the naked eye. 6 months later, it had gone away?!? :shrug:

These macro shots are not flatering to some of these LED's but down range where it matters, the peach fuz, cat whiskers and "laminar stratification" of goo doesn't matter; or so it would seem. :shrug:


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## PlayboyJoeShmoe (Dec 30, 2006)

Thanks for all you do Newbie!

I don't have the means to acquire and mess with all these new fancy LEDs. But somewhere down the road, some of my lights that don't quite "have it" will get MUCH better!


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## kogatana581 (Dec 30, 2006)

I'm seeing some green at the top of the hotspot in the 3rd and 4th photos. Is it just _my _monitor?


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## NewBie (Dec 30, 2006)

Good Morning Don!

If you look carefully at around a 45 degree angle, you will notice the Seoul P4 has an extra milky layer of silicone above the phosphor layer that is down at the die level.







Also, if you watch the die at various angles and rotate the Seoul P4 LED, the lens on it causes different magnifications at different angles, it is somewhat more aspherical shaped than a half circle of the Luxeon, if you look back earlier.


I second your suggestion on the rough reflector surfaces helping with the various defects/reflections/shadows/rings/etc, as I'd mentioned before, and the rough reflector surfaces also help with smoothing out the tint, so you just end up with smooth tint donuts/bands- where the more heavy ruddy/bumpy reflectors help out with the tint rings/donuts/bands more than just a slight orange peel. IMHO, the more agressive finish also blends out the hotspot better, but it is a personal preference for me (the intensity blending).


I took another photo, with things focused on the paper surface, up close:






Side note- from different emitters off the same strip, I am seeing different items for tint variation in the profile and such, in some ways some are better, others are worse. But it is more a trade-off this for that.

.


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## DFiorentino (Dec 30, 2006)

I applaud your attention to detail Newbie. This post has been shockingly interesting to read through. :goodjob:

-DF


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## AlexGT (Dec 30, 2006)

Very nice review, thank you for all your effort in documenting this.

I wonder if these leds come on a star? 

AlexGT


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## NewBie (Dec 30, 2006)

Currently, on the production Seoul P4 parts that I've got, they are binning by Kelvin temperature, and this one is 6500K. This is more like the old LumiLEDs method that they used with the LXHL-BW01 parts when they had the blop/glob phosphor. LumiLEDs went to great efforts in the early days to sell everyone on this technique in their techical presentations and training seminars. Thank goodness common sense won out, and they went to the color binning method based on the eye response to color that they use now. Under the old system, they take the Planckian BBL radiator line, and draw lines perpendicular to it, and create a binning structure from that. One of the big drawbacks of this system is that within one bin, you could get anything from an X1 to a X0, to a WA bin, which takes you from green to cool white to pinkis/purplish white, if anyone remembers the old days. So, under the old LumiLEDs system, this would fall in Bin Code 4, if anyone is interested.

Example:







Unfortuneately, that chart there doesn't have the tints on it, so use this as a reference:






.


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## Draper Knives (Dec 30, 2006)

Very interesting...Thanks for your research!!! Do you happen to have comparison pics of the base of LUX III and the Seoul P4 LED?

Have you tried using a dryer fabric softener sheet for static...:thinking:


Mike


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## IsaacHayes (Dec 30, 2006)

Newbie, whats with that milky gel on top of the die? It seems too as though the extra phosphor below/on the edge of the die is what causes the yellow hallo. But the XRE is sprayed all over too, but I'm guessing that either the same thing is happening, but blocked by the ring on the cree, or that there is less light shining out the side of the die to excite this phosphor, where the P4 does and shines that out.

If the "yellow edge" wasn't there, and just the center hotspot from the led, is the color even? Like would it be all blue/white, or does it go from yellow, white, to nasty blue like the older SSC zleds?

Also, can you confirm the slug size on the P4? Is it larger than the luxeons?


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## NewBie (Dec 30, 2006)

Here is a side profile of the Seoul P4 beam, with the McGizmo HD45 reflector which has a bumpy reflector surface:


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## 3rd_shift (Dec 30, 2006)

Excellent photos Newbie! :twothumbs: :bow:

It looks like a fairly inexpensive led to produce.
It just doesn't look like a lot of effort was put into durability and consistency.

I just justed off an older SX1L binned Luxeon3 and it seems to be of a good build quality with only relatively low performance, and an all around, even, nonfat milk greenish white tint.

It looks like SSC has a little ways to go imho.

A lot of light is good if it looks good.
If it looks like a white sheet of paper from inside the pet's litter box, then I'll pass for now.


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## NewBie (Dec 30, 2006)

Okay, did a quick Vf run, since folks were asking me about Vf on the Seoul P4:







One thing I noticed, is the overall tint on these changes a lot with current, but how much is for later testing. For now, above 1 Amp, whatever phosphor mix they are using really starts shifting hard, up at 2 Amps, it gets a pretty scary shade of blue (much like the overdriven 5mm do- a.k.a. angry blue). Comming back down, I noticed the tint shifts considerably over the current range as you move it around, but I'll need to some calibrated measurements to get more specific. Extremely low and very agressive thermal resistance solutions may help this issue, I'll have to look into that further.


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## Draper Knives (Dec 30, 2006)




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## NewBie (Dec 30, 2006)

Draper Knives said:


>




Hey, that looks great right about now, time for a break!


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## chimo (Dec 30, 2006)

NewBie said:


> Hey, that looks great right about now, time for a break!



Hawaiian pizza is my favourite. However, crock pot chicken stew will have to do tonight - time for supper.


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## hotbeam (Dec 30, 2006)

Interesting read Jar. 

I use a drop of water or saliva to remove the dust from the dome.... and then promptly cover up the LEDs so nothing else sticks on it. Here is a photo of the dome after 5-6 months of it in an uncovered environment. Under macro, it doesn't look that good. But that is after 5-6 months. If you cover it up soon after it is in your flashlight, you won't have these issues.






As far as the lens is concerned, a silicon lens allows for much better heat dissipation than epoxy. I suspect that is one reason why it was used.

As suggested, the orange peel McGizmo reflector will definately come in handy. I won't be happy with the visible bond wire.

Oh, at 2A, everything else would look pretty 'angry'  Their rated maximum is half of that! 

I look forward to getting my reels of U's so I can check it out also. Although I will concede to you Jar right now, my equipment range is nowhere near the capabilities of your lab.


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## NewBie (Dec 30, 2006)

hotbeam said:


> Interesting read Jar.
> 
> I use a drop of water or saliva to remove the dust from the dome.... and then promptly cover up the LEDs so nothing else sticks on it. Here is a photo of the dome after 5-6 months of it in an uncovered environment. Under macro, it doesn't look that good. But that is after 5-6 months. If you cover it up soon after it is in your flashlight, you won't have these issues.
> 
> ...




I take it that is the older glop LED in that photo?


.


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## milkyspit (Dec 30, 2006)

Very useful read, Newbie. Thanks.

Thanks, too, to those who have chimed in... JTR1962, Hotbeam, McGizmo, etc.

Nice job guys. :thumbsup:


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## wquiles (Dec 30, 2006)

Awesome thread - thanks NewBie :rock: 

Will


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## hotbeam (Dec 31, 2006)

NewBie said:


> I take it that is the older glop LED in that photo?



Yes, from the P3 range. One would hope the P4s are equal to or better than that.


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## NewBie (Dec 31, 2006)

I decided to do a set of side profiles in the smooth MagLite D cell reflector.

As you look at the photos at different exposures, you should be able to see the various tints in different areas that are not captured by a single photo. One item to take note of, for example, is in picture 3, you'll notice the cooler white center hotspot on the right hand side at the very end of the paper, then you will see the warm surround, then the very cool white flood area. Also, some of various the ring artifacts can be seen at different exposures more than others. The technique of various exposure levels is called bracketing, and is used to help make up for the short commings of digital cameras.

(keep in mind, when looking at very, very slight tinting, from monitor to monitor, some of the tints will look a bit more greenish, warmish, purplish, bluish, etc, depending on the monitor settings and the quality of the monitor)


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## SuperTorch (Dec 31, 2006)

How large is the hot spot in the Mag, the Luxeons are a tad small and on tightest focus I was hopeing the new stuff, Cree XR-E and the Seoul P4 would have a larger hot spot, maybe 50% larger. Now that its night time and since you were kind to the whitewall hunters can you make a comment for the throw junkies, thanks.


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## chris_m (Dec 31, 2006)

Does anybody know how these compare to a SSC P3 LED in terms of dimensions and beam pattern? Are they a drop in replacement for those? I have some P3 optics (though never had any P3s - bought in mistake when I had SSC P1s which were the highest efficiency power LED before the Cree XR-E), so hoping I can just drop some P4s in.


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## NewBie (Dec 31, 2006)

SuperTorch

I don't really see any difference in the focused hot portion of the hotspot size itself between the Luxeon III and the Seoul P4 in the MagLite reflector.

What I did notice is there is some tinting in the hotspot which changes as you move it in and out of the focus.

With a particular 2D MagLED that I know runs close to 350mA, I find that the Seoul P4 registers the same on my light meter @ 230mA.


----------



## NewBie (Dec 31, 2006)

Okay, I dug out the manual and figured out how to lock the movie camera exposure setting and color correction settings.

*Color tint shift with current adjustment*

I specifically noticed during my forward voltage testing of the Seoul P4, that the color shifts dramatically with current levels. Two things can cause this, one being the die color output, and the other is the phosphor (some YAG phosphors will drop as much as 60% lower output as the die heats the phosphor).

An example of what happens to one type of YAG phosphor is shown here, with the red line:
http://ledsmagazine.com/press/14132


It is unknown to me as to what is actually causing this in the Seoul P4 LED.


Anyhow, like I mentioned, I locked the exposure and white balance in the camera for this movie I took to demonstrate the color shift. The current runs from 400mA to 1.1 A in the video.


*The movie is located here:*
http://www.molalla.net/~leeper/seoulp4t.wmv


I'd estimate the part is moving from a very strong X1 bin (greenish-yellow) to way out beyond the end of the YA bin. At 400mA it is greenish-yellow and at 1100 mA it is blue. Pay attention to the corona color around the hotspot, since the camera is oversaturated in the hotspot and doesn't represent color that well there.


Thoughts-

The P4 LED appears to tint shift a lot more than other LEDs with drive current level changes, and hopefully it is just due to heating effects on the phosphor.


Early thoughts- 
I'd consider agressively pursing very good thermal transfer techniques in an attempt to help mitigate the tint shift in the Seoul P4.


My plans for checking this out further-
Getting a thick copper plate and directly soldering the Seoul P4 to it. Then to thermal paste this plate to a large CPU heatsink with a strong fan. Then retest to see if it actually will help or not.


The Seoul P4 has a rather low thermal resistance 6.9 C/W vs. 8 C/W for the CREE XR-E, and they use the same CREE EZ1000 die in them. The LumiLEDs K2 has a 9 C/W. I don't notice tint shifting in the K2 or the XR-E that is anything like what the Seoul P4 is demonstrating. (or even the Luxeon III with a 13 C/W for that matter) 

With the Seoul P4's very low thermal resistance being in the same range of other newly introduced LEDs one would figure the shifts should be similar. The shift in the blue wavelength (affects interaction with the phosphor), and also the shift due to YAG phosphor heating, should be less, unless they are using a different phosphor blend than LumiLEDs or CREE is utilizing (which is quite possible).

I hope to explore this further by directly soldering the part down to get rid of the thermal resistance of thermal epoxy and agressively heatsinking the thermal energy out of the Seoul P4 die.


The movie doesn't work for some folks, so I snapped a snapshot from two points in the video:


----------



## Nereus (Dec 31, 2006)

NewBie said:


> Okay, did a quick Vf run, since folks were asking me about Vf on the Seoul P4:


What a difference between Vf of Cree and Soeul! I wonder where this comes from since aren't they using the same Cree die? Does Cree give its highest Vf dies to Soeul...?

On the other hand this means that Cree parts should perform better than Soeul when it comes to lm/W.

-N


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## IsaacHayes (Dec 31, 2006)

Wow, that sure does shift a lot!!! I'm guessing it's their phosphor that's weird.

Nereus: It could be just a high Vf sample, one would need to test several P4's to find out. I have a XRE that is way higher than my other ones on VF, so it could just be lottery. Another thought in discussion with Newbie is the bond wires could be smaller on the P4 than the XRE, and that might cause some resistance. But we don't know without further testing.


Newbie: A bit off-topic, but is anyone using the nm sized particle YAG phosphor yet?


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## NewBie (Dec 31, 2006)

Issac,

I don't think any of the recent phosphor developments have made it into production products yet, it will be very interesting to see those get into the mix, on top of everything.

I fiddled around a bit more with my movie camera, and used the white balance to set a neutral perfect white at 700mA. I then varied the current up to 1100mA and down to 400mA. Unfortunately, my video camera has very poor latitude, and does not do a good job of capturing the lighter and darker areas so you would be able to see how the various tints in the beam of the Seoul P4 shift at different current levels.

Links to the videos:
http://www.molalla.net/~leeper/sp4twb.wmv

Zoomed on on the hotspot:
http://www.molalla.net/~leeper/sp4zoom.wmv


I added a high resolution version of the zoomed in hotspot, which shows things much better, worth the download, imho (3MB):
http://www.molalla.net/~leeper/sp4higrs.wmv


.


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## NewBie (Jan 1, 2007)

Well, I ran a second Seoul P4 thru the same drive levels, it doesn't get nearly as blue, but still shifts around.

The more and more I fiddle with these parts, the more I realize the consistency is not like the Luxeons.

Personally from what I see so far, if I were buying the Seoul P4 in a flashlight, I think myself, I'd really want to try out a batch of them, and choose the pick of the litter, unless it was a 10 dollar flashlight (and then, I'd still be tempted).

So, from what I'm seeing out of my first batch... For some, it is possible that they may get a premo choice part, and they will feel they are as good as a Luxeon (or better, since it is a lot brighter than the Luxeon). Others may get not so awesome of a part, and they won't be all that happy about it, especially those that have some conerns over tint and tint variation. Right now, about the only idea I can think of, is to ask specifically for the full ranking of the parts that comes off the reel, Flux, Tint, and Forward Voltage for the flashlight they are put in- or to ask what tint bin the flashlight is in at its rated current- like SYN @ 1100mA (roughly like LumiLEDs YA) and then what bin it falls in at it's dim current, like SUM @ 50mA (LumiLEDs UM bin).









For those that haven't seen it yet, due to tint requirements of customers, LumiLEDs has moved to tighter bins, back in May of 2006, so the chart above may be a surprise.

I understand that Seoul Semiconductor offers sub-bins, however, I've never been able to buy a single bin. The ones I've gotten so far are by Kelvin temp (6500K), which leaves you pretty wide open. Possibly if one was able to purchase a single bin, the variation from part to part would be less, and I think if I was buying an expensive light with the Seoul P4, I'd really like the bin stated.

I'm not sure at what current Seoul bins the P4 at but when I get them directly from Seoul, on the package, you will see USW0H, where U = flux 91-118 (LumiLEDs 87.4 to 113.6), SWO basically equals LumiLEDs WO color bin, and H is the same as LumiLEDs Vf H bin, but 0.03 Volts lower. 

I'm currently unsure at what current Seoul bins these at, but since the datasheet has it's Electro-Optical characteristics stated at 350mA, possibly it is done there. They also show the Relative Light Output vs. Junction temperature @ 350mA. Unfortunately, at other currents, white LEDs only generally track, and it isn't possible to specifically nail down exactly what the LED is going to do at other currents.

When soldering the slug down, if the part has not been in a sealed dry atomsphere, and they have been outside the sealed dessicant package more than 1 week, you will want to bake the parts for 10-12 hours at 60C before soldering the slug down. When washed, they recommend Isopropyl Alcohol. They recommend that if you are storing them for more than three months after shipping from SSC, that you store them in a sealed container with dry Nitrogen. Long term exposure to sunlight or occasional UV will cause lens discoloration. Avoid leaving fingerprints on the silicone resin lens. And they do not recommend covering the silicone resin lens with another resin.

Possibly, with higher dollar lights, we could get the makers to provide a tint variation plot with current or something. It would not need to be exact, only what the light typically does. IMHO, this would be helpful for these parts.


Meanwhile, I'm going to work on a video with a different Seoul P4 part to try and show you what I am talking about.


Overlayed bins:







.


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## Anglepoise (Jan 1, 2007)

First let me join others above and thank you for all this hard work you have done. Most commendable.

Now in regards to your comment below. 
Am I correct in assuming that like Lux emmiters, there is no bin info stamped on each individual P4 or XR-E emmiter ( my XR-E samples were unmarked )?

As many of us will be purchasing in under 10 quantities, we are all going to have to rely on the honesty of the vendors who are selling from reels. This is an area where the LUX III consistency was most helpful and if we start to see 'high grading' by vendors lower down the supply chain, the word 'lottery' will have to be changed to something more along the lines of 'dishonesty'. I hope I am wrong.



NewBie said:


> So, from what I'm seeing out of my first batch... For some, it is possible that they may get a premo choice part, and they will feel they are as good as a Luxeon (or better, since it is a lot brighter than the Luxeon). Others may get not so awesome of a part, and they won't be all that happy about it, especially those that have some conerns over tint and tint variation. Right now, about the only idea I can think of, is to ask specifically for the full ranking of the parts that comes off the reel, Flux, Tint, and Forward Voltage for the flashlight they are put in- or to ask what tint bin the flashlight is in at its rated current- like SYN @ 1100mA (roughly like LumiLEDs YA) and then what bin it falls in at it's dim current, like SUM @ 50mA (LumiLEDs UM bin).
> 
> 
> .


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## McGizmo (Jan 1, 2007)

NewBie said:


> ......
> Personally from what I see so far, if I were buying the Seoul P4 in a flashlight, I think myself, I'd really want to try out a batch of them, and choose the pick of the litter, unless it was a 10 dollar flashlight (and then, I'd still be tempted).
> 
> So, from what I'm seeing out of my first batch... For some, it is possible that they may get a premo choice part, and they will feel they are as good as a Luxeon (or better, since it is a lot brighter than the Luxeon). Others may get not so awesome of a part, and they won't be all that happy about it, especially those that have some conerns over tint and tint variation. Right now, about the only idea I can think of, is to ask specifically for the full ranking of the parts that comes off the reel, Flux, Tint, and Forward Voltage for the flashlight they are put in- or to ask what tint bin the flashlight is in at its rated current- like SYN @ 1100mA (roughly like LumiLEDs YA) and then what bin it falls in at it's dim current, like SUM @ 50mA (LumiLEDs UM bin)
> ...



IMHO, some ideas and suggestions here are so unrealistic that I am dumbfounded!

Hypothetically, let's suppose that a company like SureFire decides to switch from Luxeons to the Seoul P4 in some of their models. Presumably the switch would be based on a typical doubling of flux and efficacy in comparison to the Luxeons. SureFire specs are typically given on flux output and runtimes. There is no information presently given on tint, color temp and certainly no bin information provided. Bin information essentially takes one SKU and turns it into a number of new SKU's. :green:

Now, if one shops at brick and mortar, it is conceivable that a dealer might allow for on sight evaluation of all of the lights presently in inventory if the lights are not packaged with a seal or wrapper. The dealer may decide if every customer wants to test every light that it is too much trouble stocking these lights.

If the light is bought via mail order or over the internet and customers are of the opinion that they can and will evaluate each light and return it until a satisfactory unit is found, I doubt these lights will be offered for any length of time. 

Even if the manufacturer were to go to the trouble of providing a specific data sheet with each light and include its LED bin information, the variations within a specific bin are real and measurable and noticible. 

" Dear Mr. SureFire dealer,

Although the light I just purchased from you may well provide the lumens stated and run for the time period claimed in the spec sheet, I find the tint of this light unacceptable. I want something with a warmer tint and less variation throughout its beam and I want it to hold constant regardless of the level output I have selected to run it at. Please replace this light being returned with one compliant to my desires. 

- Unsatisfied Customer
Member of CPF"
_
"Dear unsatisfied customer,

As a Surefire Dealer, I have had to replace previous SureFire LED lights due to what you CPF people call pee green tints. This has been a real hassle at my end and good cause to consider droppng the line or at least avoiding sales to customers bent on using their own criteria, above and beyond the manufacturer's stated claims, to determin the acceptability of the product. Please accept a refund on this latest purchase and don't buy a LED light from us again as we make no claims to be able to satisfy your expectations.

- SureFire dealer, at least for the moment.... "_

Now this is all hypothetical and of my creation.


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## McGizmo (Jan 1, 2007)

Anglepoise,

I think the realistic approach to take regarding the Seoul P4 LEDs is that of expecting tint variations at all levels; among the LED's themselves, within the beam of a single LED and with a change in drive current.

I don't doubt that there will end up being descrimination of the LED's based on bin information, when provided. This may be at the manufacturer level to OEM. This may be at the distributor level to a customer worthy of bin issue consideration and this will likely be at the CPF level where knowledge of specific bin information is brokered to those willing to pay premium.

Terms like "unrealistic expectations" and "preposterous" come to my mind in consideration of these P4's on certain levels of _differences_ among them. 

The P4's have visual and measurable variations. If one has the means of identifying these variations and an ability to buy and sell these based on these variations, so be it. If not and if these variations are of a concern, one solution is to simply avoid the P4's. :shrug:


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## NewBie (Jan 1, 2007)

Anglepoise said:


> Am I correct in assuming that like Lux emmiters, there is no bin info stamped on each individual P4 or XR-E emmiter ( my XR-E samples were unmarked )?
> 
> As many of us will be purchasing in under 10 quantities, we are all going to have to rely on the honesty of the vendors who are selling from reels. This is an area where the LUX III consistency was most helpful and if we start to see 'high grading' by vendors lower down the supply chain, the word 'lottery' will have to be changed to something more along the lines of 'dishonesty'. I hope I am wrong.




The XR-E does NOT come in a STAR format from CREE, just the emitter by itself. As such, if you get them from authorized distributors, they will come in sealed bags marked with the exact tint bin and the intensity bin. Beyond that, you will need to trust the resellers, and the companies they are using to mount the parts, the materials used, and the process involved.




McGizmo said:


> IMHO, some ideas and suggestions here are so unrealistic that I am dumbfounded!
> 
> Hypothetically, let's suppose that a company like SureFire decides to switch from Luxeons to the Seoul P4 in some of their models. Presumably the switch would be based on a typical doubling of flux and efficacy in comparison to the Luxeons. SureFire specs are typically given on flux output and runtimes. There is no information presently given on tint, color temp and certainly no bin information provided. Bin information essentially takes one SKU and turns it into a number of new SKU's. :green:
> 
> ...




Don-

I am not sure if you have noticed, but CPF'ers already have a *long history of returning Surefire flashlights for tint issues*, and it has been mentioned quite a number of times. Surefire even replaces them for tints, and that too is documented here on CPF.

The advantage that modders have, is they can select the parts used for their mods, and maybe this is the approach that should be used with the P4, depending on the current you are driving them at (since they shift so badly).

I dunno, it is just an idea on how to deal with the Seoul P4 parts- do whatever you want, I'm sorry if you take my ideas personally. We have a long history here on cpf, on custom lights and mods, of folks stating or buyers wanting to know the brightness and tint bins, as it is important to some folks.

You yourself have often mentioned you prefer the X1 bins for over-emphasizing green plants and such in the outdoors, myself, thats not what I am usually looking for, but actually what I prefer not to see- since it is everywhere, and I don't go out hunting pine or fir trees. To each his own, I'm definitely not saying you are wrong, as only you know what you prefer best and everyone is different.

Another idea, if I didn't mention it, is just to utilize the Seoul P4 in single level lights, selecting the bin needed, that get you to the color tint you want to be at, say at 917mA, 825mA, 660mA or whatever level you are going to drive the LED at.

I'm working on finishing up a video from another Seoul P4 right now, off the same reel strip, you be the judge of the differences... I'll get it up shortly.


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## McGizmo (Jan 1, 2007)

Newbie,
I plan to use the P4's in some builds because of their flux and efficacy and *dispite* their tint variations. Same case with the Cree XR-E's. With both of these LED's, I have seen variation in tint within a specific bin to make me think that knowledge of the bin itself is not enough to insure knowledge of what you will get when you fire up the LED.

Your ideas of how these LED's should or could be implimented are your ideas. You can share them with others and you can impliment them in a light of your design and offering. You can do what ever you choose to do with your ideas. Obviously.

I have the option of considering your ideas for their merits and electing to ignore them if I find them unrealistic or unviable.

When I finally have some lights hosting the P4's to offer, I will attempt to provide all possible and pertinent disclaimers and be clear on what these lights are about. I will be clear that they do not comply with the Newbie Seal of Approval nor should one have any expectations that they do. 

Maybe it's time to stop telling us and time to show us the way? :shrug: 

*EDIT: A history of behavior or action doesn't make such behavior good or bad. Repeating history is history repeated. Out of curiousity, should the customer provide advance notice to the dealer when they plan to use a method of evaluation of a products compliance that goes beyond stated claims of the product made by manufacturer or dealer?*


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## NewBie (Jan 1, 2007)

Don-

I am not telling anyone they have to do anything at all. I'm just offering up ideas on ways of dealing with short commings.

I am not motivated to make profit by making flashlights, selling flashlights, nor am I associated with any company that makes flashlights, or invested in such. For me, this is a hobby, and I intend upon it remaining that. 

If I were to start making and selling flashlights, then it would be a job, not a hobby, and imho, much less enjoyable. Personally, I actually enjoy testing things, and finding out the results, as well as designing things, and I find manufacturing things to become a chore after a while. At the point where I'd begin making flashlights, my opinions would also probably become highly biased on what I was trying to sell at the moment, and I'd seriously start having to look at myself in the mirror a lot, a most definite catch-22 situation.

I never asked you to take any of my ideas as absolutely correct, I am just tossing out things for folks to consider.

Lets take your preference for X1 bins. Yes, they are yellow-green when compared to white. So what. Some folks on CPF prefer XO, or WO bins. Other folks really prefer YO and VO bins. To each his own, it is not my concern at all. To just say a light has tint, and to say it has no importance, except yes it has tint, is a tad odd, imho. You have had a long history of preference for the X1 bin. So, even you yourself are thus saying tint is important. Furthermore, you yourself have stressed how much more color rendering the X1 tint bin offers, and a few others support that opinion. Thats fine, nothing wrong with that, but tint is quite important to some. It is in my personal opinion a dis-service to say that tint has no importance or that there should be no consideration for the same.

Anyhow, I'd recommend that we take your personal preferences and such to PM or email, and get back on the topic.


Anyhow, here are the results from a second LED over the same range. Both of these Seoul P4 LEDs are actually from the same reel strip, in fact, side by side in the strip.

First LED here:
http://www.molalla.net/~leeper/sp4higrs.wmv

Second LED here:
http://www.molalla.net/~leeper/sp4t2nd.wmv


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## X Racer (Jan 1, 2007)

And the tint debate is alive and well... I don't see an end in sight to the tint debate. 

As a consumer, it would be great to be able to purchase only the best of the best as far as bin codes go. 

But then, as a manufacturer, what are they supposed to do ? Purchase 200 units of a certain bin, hand select the 50 units that meet the criteria for use ? What of the other 150 units that don't make the spec ? Do they charge you the cost of 4 LEDs to make up for the three that get scrapped ?


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## easilyled (Jan 1, 2007)

X Racer said:


> And the tint debate is alive and well... I don't see an end in sight to the tint debate.
> 
> As a consumer, it would be great to be able to purchase only the best of the best as far as bin codes go.
> 
> But then, as a manufacturer, what are they supposed to do ? Purchase 200 units of a certain bin, hand select the 50 units that meet the criteria for use ? What of the other 150 units that don't make the spec ? Do they charge you the cost of 4 LEDs to make up for the three that get scrapped ?



I suppose what they could do concerning output is to have a base target
for output. They could get a light-metre reading for each light and then
sell the ones that exceed the target-range for a higher price, sell the ones
that meet the target-range at the intended price and sell the ones
that fail to meet this target-range at a lower price.

I could see this type of disclosure causing problems though as most who
can afford Ti McGizmo lights are going to prefer spending more for the higher
outputs and therefore there may be a whole lot of lights left unsold. :shrug:


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## McGizmo (Jan 1, 2007)

Newbie,
This is your thread and I will bow out now. No need to waste either of our time in PM's. Enjoy your hobby.


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## NewBie (Jan 1, 2007)

X Racer said:


> And the tint debate is alive and well... I don't see an end in sight to the tint debate.
> 
> As a consumer, it would be great to be able to purchase only the best of the best as far as bin codes go.
> 
> But then, as a manufacturer, what are they supposed to do ? Purchase 200 units of a certain bin, hand select the 50 units that meet the criteria for use ? What of the other 150 units that don't make the spec ? Do they charge you the cost of 4 LEDs to make up for the three that get scrapped ?




Some people do purchase the best of the best bin tints, and we have folks making a profit here on CPF by selling them by tint, output, and even forward voltage. Thats what threads that say UXOH and XX1S are about.


I have no idea what folks will do, *IMHO* the Seoul P4 has really opened up the same old issue we had many years ago with the Luxeons when they first came out. Craig from LEDMuseum even coined the term pee-green or whatever it was. What I see is new with the Seoul P4, is that I am seeing extra tint shifting at various drive levels. This could be a big issue in low output dual stage drive lights, maybe one could get a bin that it is just bluish when you want punch, and yellow when you just need a tad of light (splitting the difference). Unfortunately, when you drive white LEDs hard, they generally shift a little blue, and when driving them lightly, they shift yellow. The Seoul P4 seems to do more of this than other LEDs I've worked with. 

Maybe folks could apply the method that Henry did with the ARC4 and HDS lights, to the Seoul P4, where you pull a few drive techniques to hold the tint more constant. Not just a PWM or CC thing alone. Definitely something to consider.




easilyled said:


> I suppose what they could do concerning output is to have a base target
> for output. They could get a light-metre reading for each light and then
> sell the ones that exceed the target-range for a higher price, sell the ones
> that meet the target-range at the intended price and sell the ones
> ...




Interesting idea, I imagine that could work, that is kind of what HDS did with their EDC60, EDC60GT, EDC60XR, and EDC60XRGT, which seemed to work for them just fine. It would also allow the maker to get extra profit off the premium parts.

Example here:
http://www.hdssystems.com/EdcUltimate.html


Well, I'm done with this video comparision testing for now, until I get one soldered directly down to a plate of copper and mount it on a CPU heatsink. Here is a third LED for comparison against the first two:


First LED here:
http://www.molalla.net/~leeper/sp4higrs.wmv

Second LED here:
http://www.molalla.net/~leeper/sp4t2nd.wmv

Third LED here:
http://www.molalla.net/~leeper/sp4t3rd.wmv


.


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## IsaacHayes (Jan 1, 2007)

I like LED #2! doesnt shift much at all. 

EDIT it does shift, more to like Y0 at the end, but on my monitor doesnt look like a straight blue led at the end, LOL!


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## EngrPaul (Jan 1, 2007)

Newbie,

Please clarify, you're testing T-Binned P4's, right?

Thanks in advance.


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## IsaacHayes (Jan 1, 2007)

I think he said they were U's.


> I'm not sure at what current Seoul bins the P4 at but when I get them directly from Seoul, on the package, you will see USW0H, where U = flux 91-118 (LumiLEDs 87.4 to 113.6), SWO basically equals LumiLEDs WO color bin, and H is the same as LumiLEDs Vf H bin, but 0.03 Volts lower.


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## EngrPaul (Jan 1, 2007)

His one chart showed a T in the part number... I'm always confused by what I see.


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## NewBie (Jan 1, 2007)

EngrPaul, 

I am testing the T bin Seoul, as that is all I have available at the moment. I have not seen U bins yet.


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## EngrPaul (Jan 1, 2007)

Thanks NewBie. Let's hope they perform better.


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## NewBie (Jan 2, 2007)

Well, I went down to Fry's and bought an overkill heatsink.

I then soldered a fourth Seoul P4 to the same 0.165" sheet of Copper that I have some CREE XR-E LEDs soldered on.

I then wired the LEDs in series to assure that each received exactly the same current, and placed a meter in series with them.

Before we get into further testing, I just want to say that not every one of these shifts the same, and you can see the results in the videos from previous posts. Some start tinting blue at a low current and some start tinting blue at a higher current, it is almost like there is a knee. 

The previous tests had the Seoul P4 thermal epoxied down to a large solid aluminum rod, definitely more thermal sinking and lower thermal resistance path down the length than you'd see in a typical setup. Soldering and heatsinking is an attempt to see if agressively lowering the thermal resistance to hold the die temperature extremely low would reduce the color shift.

Anyhow, enough with the words, here are the pictures, with a meter showing the current going thru the two LEDs (wired in series):






























































I have a video of the same test that I am working on right now, I will post it shortly.


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## NewBie (Jan 2, 2007)

Okay, got the video of the test done.

Unfortunately, the camera over-saturates towards the end, and doesn't adjust it's brightness down, so you end up with a hot white spot in the center of the blue surround.

Here it is:

http://www.molalla.net/~leeper/sp4txre.wmv


.


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## IsaacHayes (Jan 2, 2007)

Does the flux between P4's seem to be consistent, or does that vary as much as the tint shifts part to part?

What about the Vf in this regard? How do they compare to each other?


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## Gryloc (Jan 2, 2007)

Hello Newbie. I was watching this thread for a while and I finally felt like posting. Again, nice work with the testing. Is it appropriate to be so harsh and judgmental over an early production LED? I was just wondering. Do early production parts ever change much from the more mature products that may be available like 6 months later? I was thinking about trying one when more available for some projects, but I hope I am not going to be disappointed.

That color shifting in your videos are pretty extreme, like the first one (on you very latest set of videos). I am usually pretty cool over various tints, as long as they are not an ugly color, but the super blue that they turn at higher currents are pretty nasty for me (if the white balance on your camera is correct). 

What are they doing wrong with the phosphors? You mentioned using a different type, but something seems wrong about the extreme shifts. It scares me because it reminds me of accidentally overpowering the old Luxeon I and it turns that angry blue like it will fail at any moment. 

The pictures of the P4 emitter is discouraging, too. Thought the actual quality doesnt seem too bad, the way it was designed is odd. People are against the "gummy" domes. If it is like the K2 domes, I would fully accept them. How close are the "gummy" domes of the P4 to the K2? 

I had awesome experiences with the K2s physical strengths. I did some destructive testing on some of the few K2s I destroyed accidentally for my LED headlight project. The soft dome is nearly immortal to my 30W soldering iron (as is the black plastic used for the body), and the dome does well when it comes to impacts and exacto knifes. I had some large needle-nose pliers (very chubby and about 6in long) and I struck down on the top of the soft domes with a flat stop. It took some strong swings to actually do any damage. When this happens, only the jelly-like silicone between the die and the dome gets distorted. I bet it would still light up, even if it has a distorted image. Mild scrapes with the knife doesn't do much at all. I bet if you would push down, it would cut easily though.

What could they have done better with the internals of the P4 above the die? I see how the soft gel diffuses and disperses the light in a lousy way. Why isn't it clear like Luxeon and Cree? Its way too milky, as though they didn't allow the silicone with the yellow phosphor to cure before they gooped on the filler gel. Also, why does the bond wires have to bee so long that they arch up and get in the way? I bet with that long, narrow bond wire, there is some good resistance. Maybe not. Finally, is the conformal coating of the die (where the phosphor is perfectly square and even like the shape of the die) patented by Lumileds? Why did they use that puddle of goop-like phosphor and not like how even Cree did it?

Oh, one more thing. Newbie, when are you going to take measurements of the flux of these P4s? I would like to see how they compare to the XR-E, even if its a similar die. That would be cool. I suppose that even if the LED is horribly blue, and it is super bright, I might have to try some of them. Alright, good luck and thanks...


-Tony


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## Concept (Jan 2, 2007)

Amazing cooling rig there Newbie. Great job as always.


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## MSHasegawa (Jan 2, 2007)

NewBie,

It is just amazing how you go into such depth in LED analysis. Excellent job and I understand you are having fun, too. The types of data and info I get from enthusiasts like you are the reasons why I come to CPF. Thank you, I appreciate it.

If I may add my 0.02USD regarding tint/output performance of LED flashlights... As a consumer, I like to get the most for my dollar. "Most" could also mean "perfect", whatever that means. IMHO, flashlight's primary reason for existence is to provide lighting when none or lacking and to allow a person to see. Seeing can be had in many flavors, depending on the color of the beam and intensity of the beam. If I may say so, with a sub-$50 flashlight, bright is all I expect. But when spending $200+ (4, 5 or even $600!), I expect the tint/color to be pleasing to my eyes (or approximates the sun, or household 100W incan bulb, or my car's HID headlight, or etc). Not some off-color tint. Yes, very subjective. But the fact is, light quality is at the core of a flashlight.

I think Surefires are overpriced. Quality seems to be suffering lately (based on what I'm reading on CPF), too. Nice design? Yes, in a military tool kind of way. Also, if you cost out the components and manufacturing labor, you'll see a fat margin. And because of this margin, they are able to take returns and provide expensive customer service. I'm OK with that. I'll pay extra to get a "perfect" light, whatever that means to me.

I'm kind of rambling on, but what I wanted to say was that the kind of information you provide allow us to be a better informed consumer. I appreciate that.

Thanks NewBie.


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## chimo (Jan 2, 2007)

That's one hell of a colour shift between the XR-E and the P4. Looking at the colour of the DMM and copper sheet between shots, it doesn't look like the camera shifted at all, either. 

This is good to know - I hope that Seoul Semi is giving thie due attention. 


Here's a link to an interesting (and short) read  on the use of optical gels and their effect on light extraction from the die. To sum it up, the use of a high index gel increases light extraction 2.5-3 times than using no gel at all.

Paul


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## NewBie (Jan 2, 2007)

Gryloc said:


> Hello Newbie. I was watching this thread for a while and I finally felt like posting. Again, nice work with the testing. Is it appropriate to be so harsh and judgmental over an early production LED? I was just wondering. Do early production parts ever change much from the more mature products that may be available like 6 months later? I was thinking about trying one when more available for some projects, but I hope I am not going to be disappointed.




Normally, when designers design things in, and run them through their own tests, thru qualification testing, HALT/HASS, and in many industries, certification. As such, you expect the parts to have a certain amount of consistency and not to be changing, as a simple change to something like a primer that is used for silicone adhesion, can cause issues when going back thru testing. These tests take months or even years to do, so you don't want things to be changing, or in a constant state of flux. This is where some designers get in a bit of hot water, where they will design and qualify things with prototype samples, then they find out (even though the manufacturer of the device said...) that something has changed, or often discover in themselves that the parts actually changed in their product production or the field, or that some attribute changed, and is causing failures now.

This is the whole reason for production parts, as the manufacturer has now dialed things in to a point that the part will be stable for a number of years, and will not change. You design using the stated specifications, and run qualification tests to assure the parts will work and hold up in the field. So, you expect/need a part to be the same for a period of time.

Unfortunately, my past experiences so far with Seoul Semiconductor is that they are always fiddling with their production parts, much like you were getting evaluation samples as things are dialed in, which makes them more difficult to use than LEDs from Nichia, LumiLEDs, OSRAM, Toyoda-Gosei, or CREE.

One of the indicators of how well a manufacturer has a part dialed in is the consistency from part to part. I am not seeing that much consistency, imho.

Critical? These are production parts and are what they are. I've not formed an opinion on these parts yet, but it is forming. I'm just checking them out.




Gryloc said:


> That color shifting in your videos are pretty extreme, like the first one (on you very latest set of videos). I am usually pretty cool over various tints, as long as they are not an ugly color, but the super blue that they turn at higher currents are pretty nasty for me (if the white balance on your camera is correct).



Well, the parts are much more consistent at 350mA as far as the tint from part to part. Above that, some parts start to shift drastically at 500mA and some go clear up to 1000mA before they shift much. There is also a lot of color shift over the current range.

If you go back and look at the Vf curve, you will notice there is some tilt to it, as compared to the CREE XR-E, where they both use the same CREE EZ1000 die. As an LED die heats up, it's Vf drops, typically something like 2.0 mV per degree C. This may be what is going on, is the die is getting hot, and the thermal resistance is not what is stated on the datasheet. Another item one can look at is the change in wavelength with temperaturature of the blue die, which I hope to get to.

On the fourth production part which I soldered down (instead of thermal epoxy like the other three), just like the other three, it shifted right when it got up to the current (some cases only 500mA), not something that happened after some use.



Gryloc said:


> What are they doing wrong with the phosphors? You mentioned using a different type, but something seems wrong about the extreme shifts. It scares me because it reminds me of accidentally overpowering the old Luxeon I and it turns that angry blue like it will fail at any moment.



Wrong? They may just be using a different mix for the YAG than others. Phosphors is a big area of patent activity, as well as how it is mixed in it's binders, and how it is applied. All this affects how well it works.

I was hoping that using agressive thermal techniques would help this part, it doesn't.

It could also be that the thermal resistance to the die is not what is stated in the datasheet. YAG phosphors will typically start dropping in output around 60C die temperature, and continue to drop as the temperature rises. This is the material that makes the broad band yellow (as well as the rest of the spectrum), and with the blue from the LED, what we interpret as white. Some YAG mixes are better than others. For an example of how a typical YAG phosphor performs, look here:
http://ledsmagazine.com/press/14132

I don't design LEDs for a living, I just use them in my designs, and one needs to look at things carefully, or risk jumping in the cauldron. As far as what is actually going on with the Seoul P4 LEDs, one would have to talk with their designers.




Gryloc said:


> The pictures of the P4 emitter is discouraging, too. Thought the actual quality doesnt seem too bad, the way it was designed is odd. People are against the "gummy" domes. If it is like the K2 domes, I would fully accept them. How close are the "gummy" domes of the P4 to the K2?



There is quite a bit of difference, and not so much, depending on your point of view. I have not had the production parts long enough to do any sort of actual abuse or life testing.



Gryloc said:


> What could they have done better with the internals of the P4 above the die? I see how the soft gel diffuses and disperses the light in a lousy way. Why isn't it clear like Luxeon and Cree?




No idea, this is another area where the Seoul parts have had a good amount of variance. Depending on how you treat the light source, this could help or hinder, depending on your goals.




Gryloc said:


> Its way too milky, as though they didn't allow the silicone with the yellow phosphor to cure before they gooped on the filler gel. Also, why does the bond wires have to bee so long that they arch up and get in the way?



As to the cause, there are a number of things that could make this happen. It could be the supplier, the ingredients the supplier used, the production process that Seoul is utilizing, interaction with materials/steps in the production process, and a number of other things. No real idea as to the root cause.



Gryloc said:


> I bet with that long, narrow bond wire, there is some good resistance. Maybe not. Finally, is the conformal coating of the die (where the phosphor is perfectly square and even like the shape of the die) patented by Lumileds? Why did they use that puddle of goop-like phosphor and not like how even Cree did it?




Keep in mind, there are some optical effects that magnify things, however, they are long enough and tall enough to cast shadows or be in the image of the die in a reflector. Yes, LumiLEDs has a patent on the way they do the phosphor application, and at least two other ways of accomplishing the same thing.




Gryloc said:


> Oh, one more thing. Newbie, when are you going to take measurements of the flux of these P4s? I would like to see how they compare to the XR-E, even if its a similar die. That would be cool. I suppose that even if the LED is horribly blue, and it is super bright, I might have to try some of them. Alright, good luck and thanks...
> -Tony



If I get access, I'll do some lumen testing, but I am not promising anything.


Meanwhile, there is some variance from part to part, on the production devices I have. Some batches may be better, some may be worse. And since Seoul has a history of constantly fiddling with their parts/process, hopefully we will see the parts evolve or improve. A risk one takes is that unseen or unknown items may cause issues later in the field. Another risk is that you may get in another batch that are not suitable for your product. Luckily, for modders and small time flashlight companies is that it isn't that big of a deal, you can just use something else, or choose and pick from what is available.

It will be very interesting to get parts in from other supply points, and see if they show the same characteristics, or if the Seoul parts just typically have the same types of variance that they have had in the past. It will also be interesting to see how they do over time with their constant evolution on their parts.


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## ICUDoc (Jan 2, 2007)

Now THAT is a heatsink, Newbie.
THanks for the further data.
I look forward to seeing a few SSC parts driven to 800mA+ to compare different tint shifts.
The science behind two production LEDs having such different tint shifts is unclear to me. Any ideas?
THANKS for the data. Good job.


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## wquiles (Jan 2, 2007)

ICUDoc said:


> Now THAT is a heatsink, Newbie.


Those Zalmans are in fact awesome for CPU's up to 100 Watts or so, if I recall correctly. I use two of these in my dual Opteron setup motherboard. I am running two 852's at 2.6GHz and these Zalmans keep both CPU's at a very cool 20C or so. These HS's will even support my move to the 285 (dual core) Opterons sometime next year :rock: .

Will


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## PlayboyJoeShmoe (Jan 2, 2007)

Incidently... if you think funky tints show up only on these P4 LEDs, I wish I could show you the LED in my Madmax.

I'm talking side against white paper as Newbie has done. The Pink/Purple Low Dome in my Madmax shows several colors including a spot of WHITE very close to the LED. But through the NX05 it is PINK/PURPLE!

The BLUE/PURPLE LED in my KL3 got replaced with an XO LUXIII.

I rather wish my Madmax could get the same treatment!


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## milkyspit (Jan 2, 2007)

PlayboyJoeShmoe said:


> The BLUE/PURPLE LED in my KL3 got replaced with an XO LUXIII.
> 
> I rather wish my Madmax could get the same treatment!




Uh... it can.


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## NewBie (Jan 3, 2007)

wquiles said:


> Those Zalmans are in fact awesome for CPU's up to 100 Watts or so, if I recall correctly. I use two of these in my dual Opteron setup motherboard. I am running two 852's at 2.6GHz and these Zalmans keep both CPU's at a very cool 20C or so. These HS's will even support my move to the 285 (dual core) Opterons sometime next year :rock: .
> 
> Will




The one I was using here is the CNPS9700 LED, which is one of their largest versions. The smaller version has a thermal resistance of 0.16-0.12 °C/W, the large one is unspecified.

It supports: 
-Intel's Core2 Duo, Pentium D, Pentium 4- All speeds
-AMD Athlon 64 FX, Athlon 64 X2- All speeds
-AMD Opteron and Dual Core Opteron- All speeds

Found here:
http://www.zalmanusa.com/

The small one was reviewed here:
http://www.tomshardware.com/2006/04/25/six_coolers_for_amd_processors/page21.html

The differences between the small one and the large one's performance is shown here:
http://www.tomshardware.com/2006/10/16/zalman_cnps9700_led_big-ups_cpu_cooling/page2.html


Anyhow, back on topic, I did some more testing today. I used a fifth part for this testing, and found it by far shifts tint the least amount out of all five tried so far. This one will take three times the current that my worst on does, before shifting blue that much. Two people tell me they are seeing better results, maybe the batch that these came from wasn't up to snuff, I have no idea, but I do have more of them comming from multiple sources. When I get a chance, I will post some comparison results from the best and worst out of these five.

Relative measured intensity shift with temperature, supplied from a constant current source of 750mA, and monitored during the test to assure it held less than 0.1 mA movement off of 750mA, or 0.013% change, temperatures were allowed to dwell for 15 minutes to stabilize, and were held within 2 degrees C at each point. At ambient temperatures, the Vf was 3.76 and with a current of 750mA, for a power consumption of 2.82 Watts. With it's stated 6.7 C/W this puts the die temperature under 18.9 degrees above the slug temperature (some of the power goes out as light, especially with the more efficient CREE EZ1000 die that Seoul uses in the P4). Even at a 95C slug temperature, this put the die temperature at 113.9 C, well under the absolute maximum specification of 145 degrees C. The 2.82 Watts is also under the 3.8W absolute maximum power dissipation rating:








I also ran an intensity vs. current curve. Conditions are on the graph, and when I say forced air, I really do mean it...







If you take a look at the curve, you will notice the brightness drops around 1200-1300mA (beyond the maximum current specifications). The part starts shifting blue around here, which may be hurting the brightness measurement. I was very happy to see at least one of the five showed significantly less shift than the other parts I've tested so far, and it occurred at a much higher current than the worst one, which started shifting much the same, but down at the 500mA-700mA range.

I did discover something very interesting, but we will need to wait for another day for those charts...hint- It has to do with phosphor and temperature. Oh, and the blue wavelength pretty much stayed put.


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## PlayboyJoeShmoe (Jan 3, 2007)

milkyspit said:


> Uh... it can.



Uh, yeah sure. With money all things are possible.

But my Madmax getting fixed will probably happen when we're all drinking that free bubble up and eating that rainbow stew!

ENOUGH of this, I gotta get to work!


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## NewBie (Jan 4, 2007)

Well, I got good news and bad news.

Tonight, I got to looking at my Seoul P4 that shifts blue very rapidly above 500mA a little closer.

I took a set of crossed polarizers (black), and took a look at the die under magification on my LED that shifts the most. Just above 500mA I saw this very clearly:







For me it was one of those Eureka moments. I've never seen anything like this in an LED before. It only took a short moment to realize what I thought was going on. I know that YAG phosphors (which produce the broad band yellow to mix with the blue of the LED to make white) drop in output with temperature. 

So what to do next. I decided to sacrifice this LED I paid too much for. First off, I decided to take the dome off. It turns out, unlike other LEDs, this is not a rubbery silicone dome filled with a jelly consistency gel, but the whole dome area is made from the same silicone that the outside is made from. The silicone was bonded well to everything, but a little liquid release agent, and it came loose from the slug. However, it was still bonded to the die, quite well. In the process of trying to tugging and pulling the dome loose from the die (where it was still very well stuck to), the die just popped off the slug, clean as a whistle.


What I found on the back side of the die was this:







What you are seeing here, is the shinny area that was bonded to the slug, and an area that was not bonded, and has oxidized and started turning black.


Here is a closer shot:







And a shot of the die:







Anyhow, for myself, this explains very clearly why I am seeing the variation in the strip of production Seoul P4 LEDs I purchased.

Will all parts vary like this? Who knows. In my past experience of working with high power LEDs over the past 5 years or so, I've always seen that Seoul does have variation in their parts, that I was unaccustomed to seeing in other brands that I've worked with- which include LumiLEDs, Nichia, OSRAM, CREE, and Toyoda-Gosei.

This does not mean that one should expect this from all the Seoul P4 parts, it is possible that a person could get a reel of parts that don't show this issue.

I am not absolutely certain, at what current Seoul bins their LEDs. Most of the specifications, and the binning looks to be done at 350mA. Below 500mA, I could not see any trace of this issue, whatsoever, it was uniformly the same color over the die area. Close to 500mA, I could see just an ever so slight shade of pastel baby blue, and right above 500mA, it started shifting hard blue very quickly. As I approached 700mA the whole die was pretty much blue, with the corner where there was no thermal transfer showing a distinct hard blue.

Anyhow, that was my adventure this evening.


Side note- With the die wires not being isolated from the outside by an inner gel fill, I noticed the bond wires actually do move when you press on the outside. It does not take much force to sheer the bond wires from the top of the die, and I'd highly suggest that every precaution is taken to avoid distorting the dome.


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## photorob (Jan 4, 2007)

I feel like you found out who the murderer is in a crime drama.


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## Derek Dean (Jan 4, 2007)

Wow...absolutely fascinating. Seriously.... great detective work!


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## Nereus (Jan 4, 2007)

Very interesting info, thanks Newbie! Not very good quality control... Btw, in Soeul datasheet they say that the led is rated at 350 mA. But you have an idea that it is not the case?

-N


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## wquiles (Jan 4, 2007)

Outstanding detective work NewBie and fantastic macro pictures :rock: 

Will


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## NewBie (Jan 4, 2007)

Thanks.




Nereus said:


> Very interesting info, thanks Newbie! Not very good quality control... Btw, in Soeul datasheet they say that the led is rated at 350 mA. But you have an idea that it is not the case?
> 
> -N




"*The P4 emits 240 lm at 1 A* of light and features the industry’s highest luminous efficacy (100 lm/W @ 350 mA at the maximum) with only a single die, making it a brighter and more cost-effective light source compared to conventional 70 lm/W fluorescent and 15 lm/W incandescent lighting options.
"
http://seoulsemicon.co.kr/_homepage/home_eng/product/product.asp?topCODE=1&midCODE=25


If you look at the datasheet, they used 350mA for testing typical performance. The Absolute Maximum Ratings are listed after that.

I don't see 1A listed as in a maximum pulse condition. But they don't list clearly typical current levels to run their parts at.

I know McGizmo and Dat2zip have a number of their flashlight designs where they are driving it up to 917mA. Could be a language barrier, I guess I should get a hold of Seoul Semiconductor to clarify this point.


In case anyone is curious, this part is not the same part as the one I took up to 1.5A. The maximum this LED has been driven at is 1000mA (1A), and I've only taken it there for a matter of seconds. This part started shifting blue from the get go @ 500mA, and that was a sign that something was caddywhompus, so I didn't try driving it hard, or driving it for very long at currents above 700mA.


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## EngrPaul (Jan 4, 2007)

NewBie said:


> What you are seeing here, is the shinny area that was bonded to the slug, and an area that was not bonded, and has oxidized and started turning black.


 
Newbie,

It appears there may have been a foreign material in the unbonded area. I'm not sure it could have oxidized, being sealed and all.

This could happen in a surface mount soldering (or silver epoxy) attach where the one end of the component is lifted. A gap exists, and the insulative material wicks into the gap at a later process. In that particular area, heat was being created but not dissipated, so the material turned dark.

That's my take on what I see.


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## EngrPaul (Jan 4, 2007)

NewBie,

Do you have any closer shots of this picture? The southeast corner of the semiconductor appears to be lifted (thinner amount of phosphor coating).


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## yaesumofo (Jan 4, 2007)

Newbie, could you please make a diagram which shows what part of the emitter is supplied by Cree? would this come from Cree like this or does this happen after SS get the "part ind install it into their package.

Is there a possibility that this effect was accelerated by the high current tests? Can you do the same to a "virgin" emitter? 

There are just too many variables here to draw any kind of realistic conclusion. This could be a total aberration, a single bad unit or whole bad reel. Could it have been caused by high current testing?
Unfortunately this "issue" raises far more questions than it answers. Such is life.
I can't imagine a part like this having a realistic service life. Shirley large corporations who plan to use these parts by the 10's or 100's of 1000's are testing these emitters in the same way that you are. before committing to spending millions of dollars to implement these emitters into new LED fixtures in cars and boats and elsewhere. 
As this Nation makes the switch to solid state lighting we will see a lot of companies spending lots of R&D $$ in order to design super efficient methods of lighting our homes while maintaining lumen output reducing heat increasing efficiency all while producing an acceptable "new" type of light for us to see at night by. There will be companies which do not make it. Lumileds will not be one of them. will Cree? what about SS? I do not know. I do see a lot of dust on the horizon obscuring a clear view of the future. the images of the die you show here adds to this obscured view. I am sure most agree.. I look forward to what the future holds. I almost can't wait for a practical solution to replacing the compact fluorescent globes in m home with LED based systems. Wouldn't you hate buying 20 globes for your house only to find out that a MUCH better technology has just hit the market?

I believe that it is important to keep in view the much bigger picture. the picture which shows us custom and semi custom flashlight nuts as the absolute bottom of the LED food chain. We are not the reason they are spending billions on developing these new solid state light light sources. 
They aren't making these for us little flashlight users in mind!!!!
WE are very picky. Will this translate down the road to better lighting for peoples homes? Maybe. I think we are a small annoyance to these companies. 
Did I drive this post off topic? sorry if I did.
NEWBIE can you tear apart a few more of those emitters? we need a large sample set. I am sorry I can not afford to contribute much to the Newbie R&D fund but I could send something if needed.
BTW I have not been able to get my hands on any of these emitters (outside of a flashlight). Not for lack of trying. I would like to have a few for space needle builds and for some of my own crude (by comparison ) testing. Have fun!!!
yaesumofo


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## EngrPaul (Jan 4, 2007)

Those of you who might want to better understand where this pulled apart at, please see pages 2-5 of this link:

http://www.lumileds.com/technology/tutorial/

or this:

http://www.lumen.com.ua/html/info.htm


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## EngrPaul (Jan 4, 2007)

I notice over in the group buy for this emitter, quite a few people are backing out.

Which leaves me wondering, is the "sky really falling?"

I see one part with a poor solder joint, and almost an entire thread of evaluation around that one defective component. (Am I right?)

NewBie, could you put this all into perspective?


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## NewBie (Jan 4, 2007)

yaesumofo said:


> Newbie, could you please make a diagram which shows what part of the emitter is supplied by Cree? would this come from Cree like this or does this happen after SS get the "part ind install it into their package.



No, it would be flat and very shinny on the backside from CREE.

CREE only supplies the little die part shown here:
http://www.cree.com/products/pdf/CPR3CR.-.pdf




yaesumofo said:


> Is there a possibility that this effect was accelerated by the high current tests? Can you do the same to a "virgin" emitter?



No, as I mentioned, this part showed the issue the very *first time* I applied power, as I slowly turned the current up, and it showed up at about 500mA. It has not gone over 1A. The part you are thinking about is another one of the same part.




yaesumofo said:


> There are just too many variables here to draw any kind of realistic conclusion. This could be a total aberration, a single bad unit or whole bad reel. Could it have been caused by high current testing?
> Unfortunately this "issue" raises far more questions than it answers. Such is life.



With some manufacturers they don't have the tight controls of other manufacturers. I often test parts before I will consider utilizing them in a design, even from industry leaders. If you don't, you risk being burned. When I get a production part that has issues like this, where a manufacturer could have worked more on dialing their process in, or if they can't, or hasn't put in tests to prevent process problem parts from getting out the door, it is concerning for me. If it was just one of five, that would be one thing. As it stands, I see significant variations in the production parts I purchased, and have seen things that do concern me. IMHO, if I was to consider trying to use this part in a product for a production run, I'd definitely have to do a lot more testing, and I'd definitely need to obtain parts from multiple batches, and I'd want to make sure the supplier wasn't cherry picking parts for me.




yaesumofo said:


> I can't imagine a part like this having a realistic service life. Shirley large corporations who plan to use these parts by the 10's or 100's of 1000's are testing these emitters in the same way that you are. before committing to spending millions of dollars to implement these emitters into new LED fixtures in cars and boats and elsewhere.



It is hard to say much, without more testing. If a bad batch did get out the door, what is to prevent that from happening, and why did the QA department not catch it, and what is wrong with the manufacturing process that was put in place, or is it a design issue from the get go?

With some suppliers you have lots of variations, it is the nature of the beast. Luckily, not too many people count on their flashlights, and most flashlights don't see much use, but some people use their flashlights like crazy.




yaesumofo said:


> As this Nation makes the switch to solid state lighting we will see a lot of companies spending lots of R&D $$ in order to design super efficient methods of lighting our homes while maintaining lumen output reducing heat increasing efficiency all while producing an acceptable "new" type of light for us to see at night by. There will be companies which do not make it. Lumileds will not be one of them. will Cree? what about SS? I do not know. I do see a lot of dust on the horizon obscuring a clear view of the future. the images of the die you show here adds to this obscured view. I am sure most agree.. I look forward to what the future holds. I almost can't wait for a practical solution to replacing the compact fluorescent globes in m home with LED based systems. Wouldn't you hate buying 20 globes for your house only to find out that a MUCH better technology has just hit the market?



There is a city in California that purchased LED traffic lights for the power savings and for the reliability and reduced maintenance. Unfortunately, they went with the lowest bidder. To hit the cost target, the LED traffic lights manufacturer used LEDs from a Far East (non-Japan) company. Within the next two years, every single one of the lights failed, with many of them going dim in as little as six months, and they had much higher maintenance than they had with incandescent bulbs. Unfortunately for the city, they did not put anything in the contract to hold the LED Traffic Light maker accountable. The city had to eat the whole thing. However, there are several other cities that went with quality LED Traffic Lights, and the power savings, reliability, and reduce maintenance held true and they have had an outstanding experience with them.




yaesumofo said:


> I believe that it is important to keep in view the much bigger picture. the picture which shows us custom and semi custom flashlight nuts as the absolute bottom of the LED food chain. We are not the reason they are spending billions on developing these new solid state light light sources.
> They aren't making these for us little flashlight users in mind!!!!
> WE are very picky. Will this translate down the road to better lighting for peoples homes? Maybe. I think we are a small annoyance to these companies.
> Did I drive this post off topic? sorry if I did.



Right, but due to demands, companies like LumiLEDs have gone from CCT Kelvin binning, then under customer demand on to binning like XO/WO, that everyone knows, and under even more pressure and demand, many of those bins have now been sub-divided even *further*.

If you haven't taken a look at the new binning structure that came out the middle of last year you should. They sub-divided all the bins around white much further yet. Its like wow, nice (page 5):
http://www.lumileds.com/pdfs/AB21.pdf




yaesumofo said:


> NEWBIE can you tear apart a few more of those emitters? we need a large sample set. I am sorry I can not afford to contribute much to the Newbie R&D fund but I could send something if needed.
> BTW I have not been able to get my hands on any of these emitters (outside of a flashlight). Not for lack of trying. I would like to have a few for space needle builds and for some of my own crude (by comparison ) testing. Have fun!!!
> yaesumofo




These are super simple for even you to purchase. TTI, a large distributor, owns Mouser, who is a catalog house, which is very similar to DigiKey. They have been available there for at least ?two weeks? You could have them in your hot hands tomorrow if you wanted.

Direct link:
http://www.mouser.com/search/ProductDetail.aspx?R=W42180-Tvirtualkey61510000virtualkey889-W42180T


Anyhow, I did discover a few more things about these LEDs that I will go into later.




EngrPaul said:


> I notice over in the group buy for this emitter, quite a few people are backing out.
> 
> Which leaves me wondering, is the "sky really falling?"
> 
> ...



Sky falling? Looked up at the moon and stars, and they are still up there, so no.

I do wonder why of the five LEDs I've starts shifting color at a different current level. Right now, it may have to do with the method that Seoul Semiconductor is bonding the die to the slug, the materials used, the process, the design, process variation, poor batch to batch control, or whatever- who knows? Possibly they discovered it and corrected it already, but didn't post a public advisory on thier website, nor sent out thru the distributors? Maybe they just didn't catch it because testing wasn't good enough? It is all idle speculation. McGizmo assured me that the parts are extremely consistent and stellar performers from his experience, and thats why I went out and purchased production parts. Now I've been hearing there is the typical variation, and personally, with the ones I purchased, I've not had the same experience. 

Will others have a great experience or an okay experience, a mediocre experience, or a bleh experience? I do not have a clue, only time will tell. I most certainly hope that things end up more like what McGizmo talked about, where the tint is consistent, doesn't change with drive current, and are extremely robust.

I definitely was quite amazed by the level of abuse the CREE EZ1000 die, that is deep in core of the Seoul P4, was able to take, without heatsinking under a whole portion of the die. At least this holds much promise.

Don't forget, the LumiLEDs Luxeon V when it first came out. It was out at for a while, and folks were reporting it was going south in a matter of a couple of days, and I saw the same type of issue myself. It was denied that there was any issue, and it was the fault of the customer causing the problem. This went on for some time, until LumiLEDs fessed up to the problem. Then you couldn't get them for awhile, while they were looking into things. Some changes were made, which definitely improved the lifetime, and the specification was revised to a 500 hour lifetime. Since then, a more specific specification has come out, which gives you a guide on how long they are expected to last, depending on how well they are heatsink, and the drive levels.

To this day you still find the following statement on LumiLEDs White Luxeon V page:

Features
Superior lumen maintenance 
Luxeon V Portable LEDs lasts longer than any incandescent bulb 

The datasheet was revised back in 2004, and you will find this on page 9, even though they just revised it in August 2006:

Heat sink temperature: 85°C 
Current: 600 mA 
Average Lumen Maintenance After 500 Hours of Operation65%

"LUXEON V Portable is designed primarily for portable lighting and other applications requiring operating lifetimes of 500 hours and less. While the device will operate past 500 hours, its lumen maintenance cannot yet be characterized. Longer life versions of white LUXEON V will become available in the future."
http://www.lumileds.com/pdfs/DS40.pdf


The whole point here is even the market leaders make an oops on occassion, and we could go into the K2 for more examples...


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## NewBie (Jan 5, 2007)

*Consider things and comments in this one post here, all pure speculation, and no more.*

Okay, I need to get the other camera out to get a better picture, but here is what I see:






At the moment, the best I can tell right now, this looks like many of the low silver content thermal epoxies that I have used and have a number of samples of. This technique has been used with very low power 5mm LEDs, due to their low heat levels. It is possible it could be some odd solder, but from what I can see, it looks like globules held together in a matrix (I guess it could possibly be solder paste that wasn't fully heated up to the melting point). I'll know a little more when I get a chance to look at things more tomorrow night.

Thermal epoxies have a much higher thermal resistance than solder and are rarely as durable as solder. You will find that LumiLEDs, OSRAM, CREE, and others actually solder their die. I see that CREE put a 0.00012" AuSn (gold tin) layer on the backside of the die.







I'll need to get in at a much higher magnification level to tell more, and poke and prod it- for the moment, *consider things and comments in this one post here, all pure speculation, and no more.*


BTW, EngrPaul regarding your earlier comments- I found nothing at all between what appears to be a delaminated die area and what appears to be "die bonding material" on the slug.


.
.


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## 65535 (Jan 5, 2007)

That is far from a cree so the only cree in their is the PCB well I won't be buying a Seoul chip thanks newbie.


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## EngrPaul (Jan 5, 2007)

NewBie,

Thanks for (re?)stating the total number of parts in your evaluation.

Let me restate the failure I'm observing. On the picture above, marked "Thermal Epoxy?", the bottom right corner of the joint was never soldered/bonded correctly, metal to metal. The chip was never seated planar against it's mating face, instead a corner was lifted during this attach. This caused a gap at the high side. Some of that liquid seeped into the air gap during process stages after this soldering/bonding.

Another point: Seoul's T bin is significantly lower than their U bin. Aren't T-bins are components that "didn't quite" meet the output target due to flaws in materials and workmanship, but are good enough for certain applications that don't need flawless performance? If we put them through rigorous performance tests, we're only going to find out more details about those flaws. It doesn't necessarily mean that the part doesn't meet specifications. I look forward to some U-bin evaluation.

P.S. I'm not trying to stick up for Seoul, just continue to justify my $ order for more than a dozen U-bins


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## cy (Jan 5, 2007)

lots of good info as usual!


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## NewBie (Jan 5, 2007)

EngrPaul said:


> NewBie,
> 
> Thanks for (re?)stating the total number of parts in your evaluation.
> 
> Let me restate the failure I'm observing. On the picture above, marked "Thermal Epoxy?", the bottom right corner of the joint was never soldered/bonded correctly, metal to metal. The chip was never seated planar against it's mating face, instead a corner was lifted during this attach. This caused a gap at the high side. Some of that liquid seeped into the air gap during process stages after this soldering/bonding.



This area as I said, is where the thermal transfer was not occuring.

If you read, there was no material found under that area.




EngrPaul said:


> Another point: Seoul's T bin is significantly lower than their U bin. Aren't T-bins are components that "didn't quite" meet the output target due to flaws in materials and workmanship, but are good enough for certain applications that don't need flawless performance? If we put them through rigorous performance tests, we're only going to find out more details about those flaws. It doesn't necessarily mean that the part doesn't meet specifications. I look forward to some U-bin evaluation.
> 
> P.S. I'm not trying to stick up for Seoul, just continue to justify my $ order for more than a dozen U-bins




IMHO, that is really pulling things out of .... ...

Oh, did I say that? I meant stretching things beyond the breaking point.

The Seoul T bins are the ones that are easy to get your hands on, their normal parts. The U bins are the rare ones, and for many, they have been waiting to get their hands on them. It is expected that by February, they should be more plentiful.

There is a significant difference? Humm. I remember checking out some premium priced Luxeon U bins, and comparing them to a number of T bins, in an integrating sphere, and the difference between them was easily within the measurement error of the equipment. I took over another older T bin set I had purchased, and the difference was 5%, which made me feel a little better about the purchase, but not by much.

I don't know if I'd really put that much emphasis on the difference between them, unless I had a set from the same Vf, Tint, but the U and the T lumen bins, and one was seeing a very clear difference. This would be more prone to better performing die, and if you look at the die datasheet, you will see there are five bins for brightness, and twelve bins for wavelength in each brightness range measured @ 350mA on page 3 and 4: 
http://www.cree.com/products/pdf/CPR3CR.-.pdf


The wavelength also comes into play, as most YAG phosphors have a narrow wavelength range for their peak conversion of blue light to broad band yellow.

This very tight wavelength binning helps, in that it makes it much easier to hit the target of the phosphor. Each bin wavelength range is only 2.5nm wide!

With five die brightness bins, starting out at 200mW and going to 380mW, one at least gets to start out knowing the amount of light output the particular binned die makes, fairly precisely to boot.




65535 said:


> That is far from a cree so the only cree in their is the PCB well I won't be buying a Seoul chip thanks newbie.



I don't know if I'd put it that way, but so far, I'm not too happy with my purchase from this batch. I'm really hoping that I'll get some better batches in the future.

I am now much more leary about the parts, after looking at the construction and the materials it looks like they used, but I need to look much closer at the die bonding method they used.


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## EngrPaul (Jan 5, 2007)

NewBie said:


> If you read, there was no material found under that area.


 
The picture says there is


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## evan9162 (Jan 5, 2007)

no, it doesn't

Look at the picture of the backside of the die. The shiny part is the die, the black part, the overspill of phosphor. The top left section of the outline of the backside die shot is missing and broken off. It matches the shape of the phosphor left on the slug.

If you look at the shot of the intact LED, you will see that the phosphor layer is larger than the die, and creates a border around it. That's the border around the shiny part in the backside die shot.


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## KDOG3 (Jan 5, 2007)

Man, my brain hurts trying to read this thread! From what I gather the Seoul Crees' aren't as great as we'd hoped?


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## EngrPaul (Jan 5, 2007)

Going by the pictures only, the metal square is the solder joint. It should be fully shiny through the square, with the exception of some air pockets. Instead, it's dark in the lower left corner where solder didn't join, and liquid (phosphor, whatever) wicked in later. If a cross-section at 45 degrees (a cutting line from NW to SE) was done, it should reveal there is solid material on the surface of the metal at that corner of the solder joint. This is why it pulled apart so readily. Good, complete solder joints should not come apart like that.


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## Christexan (Jan 5, 2007)

I think the group-buy dynamics may be changing for multiple reasons, possible quality control issues being one, but probably not even the primary one, as they've been tested, the physical dimensions and electrical characteristics are both different than Luxeons, and I think that has as much to do with it as anything else, people were hoping pre-release that they'd be similar enough to "drop-in" replace Luxeons, now that it's clearly not the case, people are getting second thoughts...
And then to find that there MIGHT be QC issues, just adds to the hesitation or reconsideration of the XR-E, a "known" quantity now in the wild, even with it's issues.


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## yaesumofo (Jan 5, 2007)

It seems to me that these are very similar teething problems to the initial Luxeon emitters. 
I believe that a little patience is required. Give these manufactures some time to figure out these and other new technologies out. Remember these companies are not making parts designed for the close scrutiny that crazy flashlight freaks give to beams and tints. If you look at where the typical LUX III emitter is today compared to what was available when they first came out you will see major improvements. 
Give 'em time guys.
I never read anywhere that luxeon drop in compatibility was a requirement for success. The idea that the Seoul emitters aren't ant good because they will not directly replace a Luxeon is silly.
If I were a large manufacture of semi conductors I would do what ever it took to differentiate my product from the others on the market. 
Do you think that AMD should make CPU's that drop in on motherboards made for AMD chips or visa-versa? Amd and Intel do not work so that hardware (cpus) are directly compatible, They will use the same power supplies and cases, run the same software. but they use different sockets. Why should the Light Emitting Diode business be any different? Except for selfish reasons I can't think of any good reasons. We need to remember that we are talking about BIG BUSINESS. A big business which doesn't give a hoot about a couple thousand crazy flashlight freaks.
BTW I am quite happy with the flashlights I have with Cree emitters so far. 
I look forward to further developments.
Thanks for the Link NewBie. I will wait for a while for their current stock to rotate before ordering some. 
Yaesumofo


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## Hellbore (Jan 5, 2007)

So basically... Cree is still King? For now anyway?


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## EngrPaul (Jan 5, 2007)

Fair enough, yaesumofo. 

I've seen some pictures of defective Crees from group buys... everybody has to troubleshoot defects out of their production lines.


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## IsaacHayes (Jan 5, 2007)

Take time to get it right? There is serious manufacturing problem here that is unacceptable. They need to get their die bonding down better, and hopefully that will take care of the blue shift issue. Having a part shift that much blue is unacceptable, especially when they advertise 240lumens at 1amp! Notice how the cree doesn't drop off in lumens when driven all the way to 2amps! The SSC ZLED P4 drops at 1300ma or so, which you would not think to be the case, since the die is on metal and not ceramic like the cree. You'd expect the thermal transfer to be superior.

Clearly they've gotta get their assembly process fixed as it's not performing to spec if you ask me. If they fix it then it could be a great part. I think Newbie has found out the main cause of it. This may even be why the tint is uneven in the beam coming out of the LED. The phosphor and application may not be the problem but the uneven temperature of the die.


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## evan9162 (Jan 5, 2007)

> Do you think that AMD should make CPU's that drop in on motherboards made for AMD chips or visa-versa? Amd and Intel do not work so that hardware (cpus) are directly compatible, They will use the same power supplies and cases, run the same software. but they use different sockets. Why should the Light Emitting Diode business be any different?



You are forgetting the past. In the past, all AMD chips were 100% drop-in pin compatible with intel chips. That was the only way they could get into the market. It's only in recent years that AMD has been able to blaze new trails and require a new socket and mobo to use their CPUs. They only did that after gaining some marketshare, mindshare, and customer confidence by producing chips that were drop-in replacements for intel CPUs. AMD chips were this way from the 286 (early 1980s) through Socket 7 systems (pentium MMX / AMD K62, etc). So AMD had to conform to intel's interfaces for almost 20 years before being able to call the shots.

It's extremely arrogant (and fatal) for a tiny company to try to break into a market by requiring new tooling or a completely new interface when competing with a very large, well known, and entrenched competitor.

Right now, it's in the best interest for Seoul to make their power LEDs completely drop-in compatible with luxeons. I mean, they went to the effort of making their power LEDs look exactly like a luxoen, they should just make them optically and electrically compatible as well. They are a newcomer to the market, and for them to get a good enough foothold to actually start calling the shots, they need to get a large customer base. They are going up against lumileds right now, and the best way to do that and be successful is to offer a fully drop-in replacement for Luxeon LEDs that require no (or very tiny) change(s) mechanically, optically, and electrically.

To do otherwise would be to repeat mistakes of the past (hint - read up on NextGen CPUs)


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## Christexan (Jan 5, 2007)

yaesumofo - I never said that the lack of "drop-in" ability was going to hurt the P4's commercial success, only that the apparent drop in interest in CPF group buys now that they have been tested in the real world, may partially be due to the fact that some (including myself) hoped the emitter would be a simple "Lux replacement", but since the slug is not only not neutral but is actually reversed from non-neutral luxeons, and the physical dimensions mean the luxeon optics/reflectors won't fit properly without more work, means that instead of "buy, disassemble light and remove old Luxeon, epoxy new P4 emitter and resolder, reassemble light", now modifications to circuits, reflectors, etc are required. If 20% of people in a group buy wanted a simple drop-in replacement, they may now be reconsidering. 
Never said anything about commercial success, our group buys are nothing compared to commercial volumes of LED makers. As I've said many times myself, CPFers have virtually no effect on commercial success of any LED mfger, we are a blip, but if I as an individual was waiting to see if a P4 could easily replace a Lux III, signed up for a group buy, and then found that it not only won't work properly electrically or physically as a drop-in replacement, and it also may or may not have some significant manufacturing defects compared to the Cree brand part (I am not saying this, only that a sample of one so far did), then I might drop my interest a degree, as I'm sure some others might consider also.


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## Hellbore (Jan 5, 2007)

I wish someone would scrutinize the U bin of these LED's and see if these kind of problems are common or just isolated incidents!

I just bought one of the U bins today and I'm excited to try it in place of a Lux III...


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## chris_m (Jan 5, 2007)

evan9162 said:


> It's extremely arrogant (and fatal) for a tiny company to try to break into a market by requiring new tooling or a completely new interface when competing with a very large, well known, and entrenched competitor.
> 
> Right now, it's in the best interest for Seoul to make their power LEDs completely drop-in compatible with luxeons. I mean, they went to the effort of making their power LEDs look exactly like a luxoen, they should just make them optically and electrically compatible as well. They are a newcomer to the market, and for them to get a good enough foothold to actually start calling the shots, they need to get a large customer base. They are going up against lumileds right now, and the best way to do that and be successful is to offer a fully drop-in replacement for Luxeon LEDs that require no (or very tiny) change(s) mechanically, optically, and electrically.
> 
> To do otherwise would be to repeat mistakes of the past (hint - read up on NextGen CPUs)


You seem to be completely ignorant of the LED market, and how insignificant we are here at CPF. SSC couldn't care less whether or not we can drop in their LEDs as a replacement for Luxeons - there are plenty of optics specific to their LEDs out there which manufacturers can use (assuming the P4 matches the existing SSC LEDs), and plenty of SSC LEDs already in use in various products. Meanwhile neither are they a tiny company nor a newcomer to the market - they simply have much less exposure here due to the relative non-availability of their LEDs to the general public (I bet you didn't know that before the XR-E, the power LED with the highest lumens per watt you could actually buy was made by SSC - I got some of those over a year ago). As to the idea that they actually tried to make their LED look like a Luxeon :lolsign:


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## McGizmo (Jan 5, 2007)

Hellbore,

I too find this problem here as a concern. I have been building with U bin P4's in the V0 tint bin and aside from some possible and what I consider minor, tint variations, I have not seen this problem. I have not noticed any shift due to current like Newbie has reported. Lux and Flux monitoring have been indicative of parts performing as one would expect as well. Actually the flux and lux have been most impressive! Max current I have applied has been from the DB917 drivers so about 920 mA. 

The spec sheet I have seen on the P4's lists max current as TBD. Since Seoul has given a release of flux based on 1 amp and since the EZ1000 itself is a 2 amp part, I am comfortable in driving these LED's at 900+ mA in a flashlight until or unless some other max is provided by Seoul as a guideline.

My personal plan is to monitor any of the lights I build with the P4's and if I see any with indications of strong color shift, I will pull those LED's out and simply not use them. 

In retrospect, it would have been informative on this one bad apple that Newbie got to have tried to get a measure of its flux prior to autopsy. I doubt the LED would perform as one would expect it to. :shrug:


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## evan9162 (Jan 5, 2007)

chris_m said:


> You seem to be completely ignorant of the LED market, and how insignificant we are here at CPF. SSC couldn't care less whether or not we can drop in their LEDs as a replacement for Luxeons - there are plenty of optics specific to their LEDs out there which manufacturers can use (assuming the P4 matches the existing SSC LEDs), and plenty of SSC LEDs already in use in various products. Meanwhile neither are they a tiny company nor a newcomer to the market - they simply have much less exposure here due to the relative non-availability of their LEDs to the general public (I bet you didn't know that before the XR-E, the power LED with the highest lumens per watt you could actually buy was made by SSC - I got some of those over a year ago). As to the idea that they actually tried to make their LED look like a Luxeon :lolsign:





Your post might be more effective without the thinly veiled insults.

No where in my post did I state or imply that drop in capability had anything to do with our needs here. The vast majority of current applications where luxeons are primarily used would require a drop in replacement for SSC to make inroads in those fields. I'm talking about things like architectual lighting, traffic lights, LCD backlighting, vehicle lighting, etc. In all of those situations, mechanical and optical compatability would need to be identical to that of a luxeon for a manufacturer to consider switching parts. Redesigning enclosures and optics is a major undertaking, reducing the incentive to use a different part.

And if SSC didn't "try" to make their parts look like a luxeon, how come every other major power LED maker's parts look completely different than a luxeon? All of the other major players (Nichia, Cree, Osram, Lamina) look COMPLETELY different than luxeons.


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## AndyTiedye (Jan 5, 2007)

CPF is a blip. A blip on the radar screen by which we can see what the new technology looks like way before it is in commercial products.


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## Hellbore (Jan 5, 2007)

AndyTiedye said:


> CPF is a blip. A blip on the radar screen by which we can see what the new technology looks like way before it is in commercial products.



That may be true, but I think I speak for everyone when I say, we love CPF with every fiber of our body...including our peepee...


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## NewBie (Jan 5, 2007)

EngrPaul said:


> Going by the pictures only, the metal square is the solder joint. It should be fully shiny through the square, with the exception of some air pockets. Instead, it's dark in the lower left corner where solder didn't join, and liquid (phosphor, whatever) wicked in later. If a cross-section at 45 degrees (a cutting line from NW to SE) was done, it should reveal there is solid material on the surface of the metal at that corner of the solder joint. This is why it pulled apart so readily. Good, complete solder joints should not come apart like that.




Sorry, it is definitely not solder.


I just got home, and I'll get some pictures taken and up shortly.


.


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## thezman (Jan 5, 2007)

While all the info in this thread is great, (and thanks NewBie for all the work), I pretty much decided that I'll just spend some money and test some of these out and see if they fill the need I want them to. And I won't be micro analyzing them, I'll just plop them into a couple lights and go from there. If I don't like them, in the trash they go. Can't get any simpler than that.


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## EngrPaul (Jan 5, 2007)

NewBie said:


> Sorry, it is definitely not solder.


 
Silver epoxy? Some sort of bonding feature, not necessarily solder.

OK I await you additional info.


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## EngrPaul (Jan 5, 2007)

thezman said:


> While all the info in this thread is great, (and thanks NewBie for all the work), I pretty much decided that I'll just spend some money and test some of these out and see if they fill the need I want them to. And I won't be micro analyzing them, I'll just plop them into a couple lights and go from there. If I don't like them, in the trash they go. Can't get any simpler than that.


 
This is where I am.

I installed some WH XR-E's, and a few of them turned out to be really green. Oh well, I've ordered some WC's to replace them. I suppose it's a game of trying different things, and moving on when necessary.


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## NewBie (Jan 6, 2007)

Die bonding material.

I appologize about some of the dust ahead of time. We are looking at a die that is actually a tad smaller than 1mm by 1mm. When the dome is on, magnification takes place and makes the die look much bigger than it actually is.

As such, dust starts looking pretty big at these magnifications, and I didn't dust my lenses before hand. I noticed it part way thru my photos, and cleaned things off.


If you look flat at the surface, or normal the material actually looks grey, and if you look closely, you can see a few shiny spots, those are flat areas that were on contact with the die. When you are perpendicular like this, it appears black, grey, and white (flat spots):








However, if you look at any angle it has a tan appearance. If you look carefully, you'll see a spot where the thermal epoxy did not break loose of the slug, and instead broke loose of the side of the die, and left a bump there at 1 o'clock. The thermal epoxy that was used sticks well to the glassy sides of the die, but it didn't stick as well to the slug as it did there. However, on the solder bottom of the die, it stuck better to the slug than the die, and that is most what we are looking at:







An angled shot of the material up closer:







Looking again from angle, closer yet, so you can see the side view, instead of where the occasional flat surface touches the die, like you see from the top.







Looking even closer yet:







Here is a top view, perpendicular to the surface, where you can see the occasional surface that touches the die, and the valleys in between. The white blurry areas that you see, if you focus up and down, you can actually see the slug surface below in the porous matrix:







Here I went over to the edge to make things very obvious. I am focused on the slug surface in the top half of the picture, and you can see the slug surface between the clumps of goo in the bottom half:







Same shot from another angle:







And closer yet:






Here is a shot where I focused on one of the pieces of epoxy that didn't stick to the glassy sides of the die:







And the dome + bondwires + die, just as it came off as one assembly, the RTV + RTV+phosphor, actually stuck better to the die than the thermal epoxy did!







Finally, lets go back and look at the die shot, taking notice where the thermal epoxy stuck to the sides of the glassy die better than the AuSn bottom of the LED die:







Anyhow, enjoy! It was much more facinating in person than it is in photos.


.
.


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## EngrPaul (Jan 6, 2007)

Thanks Newbie. I understand what's going on now. The failure mode is similar to what I state, just not at the solder layer. 

As was already stated, it would be interesting whether or not this bonding defect is located in a portion of the subassembly also used in the Cree XR-E.


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## NewBie (Jan 6, 2007)

Seoul does not use the SiC ESD diode sub assembly. 

The failure is in the epoxy used by Seoul to direct bond the die to the slug, and the porous open epoxy matrix delaminated from the CREE die at the thermal and rear electrical interface, but yet stuck to the glassy sides of the die better than even the substrate for 3 out of 4 sides.


*--> Disqualifier: My own personal feelings, not anything I'm stating as fact or whatever, below*

IMHO, especially after looking at the construction methods, personally I don't think I will personally be using these, and if I did, I personally will not put them in any of my personal expensive flashlights. Maybe something like a Lumapower or a Nuwai Q3. For myself personally, I'd definitely be very tempted to run them at low powers (less than 350mA), and would not personally use them in anything I personally would want to last or personally count on. I personally would be very tempted to get as much heat as possible out of the LED with heatsinking I'd personally consider quite robust.

With the failures I personally had with parts I personally purchased, and the variations I personally experienced between the parts, it reinforces my personal own opinion I metioned above.


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## evan9162 (Jan 6, 2007)

are you sure that's your *personal* opinion?


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## McGizmo (Jan 6, 2007)

Hi Newbie,
How are dice typically bonded to the slugs? If epoxy was used here, was it also electrically conductive epoxy and hence the anode connectivity? Would one or could one measure resistance between the anode lead tab and the slug to test connectivity of die to slug?

This part was obvious from the get go to you as being suspect. Do you think other less obvious LED's will have premature failure due to an epoxy bond? Will this failure be due to thermal build up? 

Is epoxy not acceptable as an adhesive? I have had no trouble lifting LED's from stars or even from anodized sinks that have been epoxied as the mechanical bond to some of the smooth surfaces is just not that great. There appears to be delamination in this bad part. Was the delamination a result of some trama to the assembly after assembly or do you think it could have been a bond flaw at assembly time?

On this particular LED, what has its history been with your testing? Could it have suffered some thermal abuse prior to sufficient sinking? Was it soldered to a heat sink and if so, could the process of soldering it have had ill effect?

In fairness to potential and unwitting users of these LED's should Seoul be contacted and told to cease production of the P4's until they get a better assembly program in place?

In assuming that your personal opinion on these LED's is not a case of over reaction, what do you suppose should be done?



> Seoul does not use the SiC ESD diode sub assembly.
> 
> The failure is in the epoxy used by Seoul to direct bond the die to the slug, and the porous open epoxy matrix delaminated from the CREE die at the thermal and rear electrical interface, but yet stuck to the glassy sides of the die better than even the substrate for 3 out of 4 sides.
> 
> ...


----------



## NewBie (Jan 6, 2007)

McGizmo said:


> Hi Newbie,
> How are dice typically bonded to the slugs? If epoxy was used here, was it also electrically conductive epoxy and hence the anode connectivity? Would one or could one measure resistance between the anode lead tab and the slug to test connectivity of die to slug?



The dice are typically soldered to an ESD sub-carrier assy, like with the Luxeons and the CREE. The CREE SiC ESD diode is soldered to the substrate. I know this as fact, as I have actually unsoldered a die from an XR-E and re-soldered to a heat pipe. 

I've also unsoldered the Luxeon die, shown here:







From the Luxeon ESD diode shown here:







The electrical resistance of even a few points of silver is going to be rather low, and if you look carefully at the Seoul P4, you will notice there is a bond wire that is opposite the three negative bond wires. The electrical resistance of this gold wire might mask anything that could be measured with a sensitive milliohm or micro-ohm meter.

What might work, is to watch the Vf shift from when the die is cold to when it gets hot. Hotter die will rise more than cooler die.

How one would assure long term reliability from some sort of test one could do might be a little tough. Here I'd be inclined to feel that you'd have to build 10,000 or so of them up, and run a test for a few years. The problem with this, is Seoul Semiconductor is constantly fiddling with their processes, so that would only tell you if that one batch held up over time. And you'd want to thermally cycle them at the same time, or at least turn them off until room temp, then back on, until the temperature stabilized.

One could also run the LEDs across several different current levels and capture the shift in tint, but since tint shift can be caused by other things, it isn't a definite thing. But, you might be able to weed out the ones that have obvious issues from the get go. The only reason this might work, is I'm seeing almost a break point where to color takes off blue, and that should be obvious.




McGizmo said:


> This part was obvious from the get go to you as being suspect. Do you think other less obvious LED's will have premature failure due to an epoxy bond? Will this failure be due to thermal build up?



Yes, I've worked with Seoul's LEDs before, and have some experiences with their previous parts. Whether the other LEDs that looked better will have failures over time is pretty hard to say, but it is definitely something to suspect. One could do a few hundred or few thousand thermal cycles, or even a little bit of thermal shock (tough to know at what point you are exceeding specifications on weak items like the epoxy), and not exceeding the slower thermal pre-heat ramp they specify for soldering. This would be a better question for a materials scientist, imho.

This part here did not experience thermal build up, shock, or whatever. It was simply thermal epoxied, with more than adequate heatsinking. The very first time it was turned on, it showed a rapid blue shift at around 500mA. I've got other parts that shift above this, and one that holds on clear up to 1500mA (which is exceeding it's rating).

Now, if you are saying thermal build up in a product and causing pre-mature failure, that would be something I'd be thinking about, and addressing any way I could, as that should help lower the stresses that will be present inside the part.




McGizmo said:


> Is epoxy not acceptable as an adhesive? I have had no trouble lifting LED's from stars or even from anodized sinks that have been epoxied as the mechanical bond to some of the smooth surfaces is just not that great. There appears to be delamination in this bad part. Was the delamination a result of some trama to the assembly after assembly or do you think it could have been a bond flaw at assembly time?



Not being a materials scientist, it is hard to say for sure. Surface prep is often of utmost importance when using many epoxies/RTV/silicones. What ever they are doing for their silicone bonding process is pretty decent, imho. When I've seen failures with bonds, on something that should handle the forces according to the datasheet on the substrates that were bonded together, it is often poor surface prep, substandard epoxy was supplied, or the designer forgot to consider something like the CTEs of the two materials joined, or in the case of two materials with differing CTEs- the designer didn't specify a minimum bond layer thickness of epoxy, the production process has poor control, or they are not doing it according to the specification. No idea if it is adequate or not, but I am seeing variations in these production parts I purchased from Mouser- and one that could cause what I am seeing is delamination, but the others could be due to something else. I've got one that has blue tint around it's four edges when driven at 700mA, and the one that runs up at 1500mA without excessive shift doesn't show this.

It would be hard to cause trama, it is recessed, but I do not know their process, so anything here would be pure speculation.




McGizmo said:


> On this particular LED, what has its history been with your testing? Could it have suffered some thermal abuse prior to sufficient sinking? Was it soldered to a heat sink and if so, could the process of soldering it have had ill effect?



It was thermal epoxied, so no thermal shock or anything. It had great heatsinking from the get go. It showed the blue shift the first time I slowly ramped up the current, right around 500mA. The tape carrier packaging showed no signs of being crushed, bent, or other issues that might indicate something happened after they were packaged at Seoul.




McGizmo said:


> In fairness to potential and unwitting users of these LED's should Seoul be contacted and told to cease production of the P4's until they get a better assembly program in place?



Humm- It really isn't my place to say what they should do. They may want to screen portions of production runs, and life screen, if they are not already. The screening may need to be more rigorous. I've seen a video of a Luxeon lookalike part that the only thing that was done was to test them at the binning current, and that is it, the binning was the only screening. Hard to say, but one might want to talk to the designer of this part himself, and not thru the sales/marketing force, and get his take on things, not some toned down marketing speak.

Better yet, if others find this issue in parts they have, contact their engineering, send them back to Seoul, and let them evaluate what is going on, since only they know what is actually used, the process, the intent, and such.

IMHO, the customers using these parts might want to consider doing some testing of their own (in any case), especially on something that is such cutting edge technology and new processes/materials used.




McGizmo said:


> In assuming that your personal opinion on these LED's is not a case of over reaction, what do you suppose should be done?



Be cognizant of any failures or wierd behavior, even odd tint shifting, and if one finds them, to be dynamically proactive. Most especially for the consumer of the end product. If I was the consumer, I'd really want to consider the warranty offered on the light, and the past reputation for warranty handling of the company. IMHO, your reputation in this area is high shined Sterling Silver.

I've got more parts inbound from various sources, it will be very interesting to see what happens with those parts. I'm really hoping for the best, these Seoul parts only require heatsink shimming and reflector grinding to retrofit into existing Luxeon flashlights, so they could be useful for a lot of CPF'ers.

Right now, I'm not going to go out and buy a bunch to modify my own lights, but I may wait, and see what the long term experience is on these parts for others.

As I've been writing this, I've been considering making a circuit that would turn the parts on for a period of time, then turn them off for a period of time, to see how this Seoul P4 construction method holds up. One of the questions, is do I heatsink the part excessively, or do I heatsink it such that the die hits 125C, which is 20C lower than it's maximum specification. Or do both...which is where I am leaning....

It is possible, that somehow, I beat all the odds, and ended up with bum parts. It is really hard to say, without buying a few hundred parts from each of multiple runs, and doing a whole test program...
.


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## cy (Jan 6, 2007)

newbie, have you tried using a Staticmaster brush with polonium 210? http://www.unitednuclear.com/isotopes.htm
http://www.orau.org/PTP/collection/consumer products/staticeliminator.htm



NewBie said:


> FYI, I rinsed off the Seoul P4 again, it keeps reaching out and grabbing dust out of the air... : (
> 
> If I decide to use many of these, I might think about making my own mini laminar flow bench, along with a +/- ion generator for equalizing charges to help keep the static down. Besides rinsing with water or isopropyl alcohol/water mix, anyone come across any great ideas on removing/preventing the dust collection on the Seoul P4?


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## chris_m (Jan 6, 2007)

evan9162 said:


> No where in my post did I state or imply that drop in capability had anything to do with our needs here. The vast majority of current applications where luxeons are primarily used would require a drop in replacement for SSC to make inroads in those fields. I'm talking about things like architectual lighting, traffic lights, LCD backlighting, vehicle lighting, etc. In all of those situations, mechanical and optical compatability would need to be identical to that of a luxeon for a manufacturer to consider switching parts. Redesigning enclosures and optics is a major undertaking, reducing the incentive to use a different part.


You're assuming firstly that SSC don't already have a part of this market - presumably on the basis that Luxeons seem a lot more prevalent to us as they're what are more readily available in the consumer marketplace. Secondly that it isn't fairly straightforward to drop in a new LED and optic, given that most optics manufacturers already offer SSC specific models with identical dimensions to Luxeon optics. That's always assuming any manufacturer would be interested in a drop in replacement anyway - I'm not convinced that's the way the high volume (ie tooling costs are a minor cost) market works.



> And if SSC didn't "try" to make their parts look like a luxeon, how come every other major power LED maker's parts look completely different than a luxeon? All of the other major players (Nichia, Cree, Osram, Lamina) look COMPLETELY different than luxeons.


How about the second one down at http://www.nichia.com/product/led-smd-powerled.html - in any case there are only so many ways to skin a cat, and I'd be more surprised if some LEDs from different makers didn't look similar. What's more, the P4 is more or less a drop in replacement for the SSC P3 LED, which has been out for quite a while - unless of course you're actually suggesting that that's the point they copied Luxeon!


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## chimo (Jan 6, 2007)

Newbie, great job on the detective work, pics and write-up. 

Seoul Semi states a fairly low thermal resistance (6.9 degC/W). Do you think they achieved that while using thermal adhesive instead of soldering the die by omitting the ESD diode?

Paul


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## NewBie (Jan 6, 2007)

chimo said:


> Newbie, great job on the detective work, pics and write-up.
> 
> Seoul Semi states a fairly low thermal resistance (6.9 degC/W). Do you think they achieved that while using thermal adhesive instead of soldering the die by omitting the ESD diode?
> 
> Paul




No, not really. CREE uses a SiC ESD diode, SiC is one of the areas that CREE is also a leader in, and has been for awhile.

"SiC is an excellent thermal conductor. Heat will flow more readily through SiC than other semiconductor materials. In fact, at room temperature, SiC has a higher thermal conductivity than any metal. This property enables SiC devices to operate at extremely high power levels and still dissipate the large amounts of excess heat generated."
http://www.cree.com/products/sic_sub_prop.asp


CREE actually makes very durable rectifiers/diodes from SiC some that have sub 1 C/W thermal resistance.
http://www.cree.com/products/pdf/CSD20030D.H.pdf


----------



## 3rd_shift (Jan 6, 2007)

It's been said many times before, but again...
Excellent pictures! :goodjob: 

It might be interesting to see what equipment SSC is using to try to make these with.

That's clearly some pretty bad solid state component manufacturing.
It should be interesting to see where these leds end up being installed into. 

Thank you Newbie for finding this out for us.


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## McGizmo (Jan 6, 2007)

Newbie,

Thanks for the point by point responses. 

After Luxeon and Cree solder their dice to a ESD device, is the ESD device then soldered to the slug? I assume the answer is no in the case of the XR-E due to the isolation of slug to die.

Is it possible that the bonding material used by Seoul in this assembly is up to its required task providing a proper bond is accomplished? 

Without speculating on the materials used and their ultimate viability and accepability in this application, there are a few things you observed which certainly point to a part that should be considered a reject. The obvious color shift with variation in Vf and the lack of uniformity of tint in viewing the die itself. This led you to taking the LED apart and your discovery of an incomplete and questionable bond layer. 

I believe there is speculation that this poor bond layer would put the die in a position of excessive heat and inadequate thermal relief when operated at specified drive levels. This would lead to poor lumen maintenance as well as color out of spec, presumably. Would this also likely be evident in flux output being below expectation?

I have no idea how these LED's are made or what type of QC is present in the various plants. From the outside and with some experience with being sampled numerous times by Seoul, I will throw out some observations and comments of speculation more than anything else. It has seemed to me that Seoul have been very fast at taking a new die and packaging it for market evaluation/ acceptance. In the past, I have received a number of LED's which were pretty good but not up to market level; close but no cigar. It seemed that Seoul also recoginzed this and back they went and out came the next iteration. I received a sample from them a few months ago that looked like a Nichia ceramic square box (jupiter style) but with the gull wing lead frames like the Luxeon. This LED had the flux of the XR-E and I believe it was host to the EZ1000 chip. The LED had a large phosphor dome for lack of better description and it may have been viable for fixed lighting but the light image or object was way to large for consideration of collimation. It seemed that Seoul now had the flux to compete but not the color consistency or image size. About a month later, the P4 shows up.

So I too have been given the impression that Seoul has been under an accelerated chain of trial and error and numerous new designs in an attempt to get to market level for acceptance. Tint variations aside, I believe the P4 has now brought Seoul to the forefront and in some applications to the lead. In their rush to get there, have they brought a flawed design with them or have they not dotted their I's and crossed their T's with the intent of first checking the market acceptance and viability of this latest itteration? :thinking: :shrug: If this P4 assembly is sound with proper compliance to procedure in assembly and manufacture, that is one thing and likely something they can fine tune if they can rest on the design for a while. They can go back and dot the I's and cross the T's I would think. 

Since I haven't experienced first hand a "dud" like this one here but I have experienced numerous exceptional performers which do not have tint shift as a function of Vf change, I am real impressed with the P4. The LED does perform admirably! I do not know if the design is sound when manufacturing is in compliance nor what to expect if manufacturing is not in compliance. 

The Luxeon V was found to have problems and it seems the design itself was weak as the part never got past "portable" applications standards. Ultimately in the case of the P4, where will it end up being? Are the good parts not only good on first impression but built for some time to come? Given the impressive efficacy of the P4 and its claimed low thermal resistance, it would seem that it should and could be a part that procduces light and adequately dispells its excess in heat. A 90 lumen/ watt part is not saddled with a lot of thermal energy it needs to dissipate. Even this obviously bunk part reviewed here was not a case of instant death or catestrophic failure. We don't know for certain that this blue boy wouldn't have limped on with its blue output for a good number of hours, do we? If the die in this part did not exceed its specified opperating temperature as a result of incomplete bond it may well have held on, yes?

A poor bond is a poor bond and no two ways about it. If the bond were proper and complete, would it be considered appropriate? It is really a shame that this "dud" wasn't tested for flux. I wonder if the part would be capable of high flux with its flawed assembly in the first place. Can you get a U bin flux part with a voided die bond, I wonder?

We have seen a bad apple here but what does that tell us about the good apples?

This LED had an obvious birth defect and one that was seen immediately. Do we know the ramifications of this defect and can we assume a life expectancy for it as a result? Because it had an obvious defect, does this imply that others will have the same defect but not be obvious?


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## EngrPaul (Jan 6, 2007)

EngrPaul said:


> Seoul's T bin is significantly lower than their U bin. Aren't T-bins are components that "didn't quite" meet the output target due to flaws in materials and workmanship, but are good enough for certain applications that don't need flawless performance? If we put them through rigorous performance tests, we're only going to find out more details about those flaws. It doesn't necessarily mean that the part doesn't meet specifications. I look forward to some U-bin evaluation.





NewBie said:


> IMHO, that is really pulling things out of .... ...


 
My HAT? 



McGizmo said:


> Newbie,
> Can you get a U bin flux part with a voided die bond, I wonder?


 
Careful Mac  Where are you talking from? :naughty:


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## McGizmo (Jan 6, 2007)

Newbie,

IMHO, you anticipated tint issues with Seoul because of previous experiences and came into the P4 with an expectation of problems and sceptisisim (sp). I think you found exactly what you expected as well as were hoping to find. You got _your_ lottery winner.  

Further, with winner in hand, it has allowed you to make a statement of your personal view that you wouldn't use a P4 in anything beyond a disposable toy, as it were. 

I am not questioning the veracity on your predisposition towards the Seoul LED's and I believe you have your just cause to anticipate the problems you have.

Your view may well be sound of reason and steps in logic but you have not provided justification for me to come to a similar personal opinion. I don't have the background to follow your steps and could use some help here. I have some U bin P4's that do not exhibit any noticible shift to blue as the current is increased. Can you provide me with a theoretical step by step cause and effect on how these LED's fall short of expectation and do they untimately fail?

*EDIT: Paul,
I assume that Seoul is likely buying the EZ1000 dice from Cree in a range of poetntial flux that could well explain the two flux bins they are sorting into regardless of the quality of and compliance to assembly procedures used. They may have T bin part that is a more efficient job of packaging of the particular die than would be the case of a steller die they have packaged and binned as a U. The underlying question here is can the EZ1000 reach expected performance levels if hampered by a flawed and voided bond layer?!?! *


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## IsaacHayes (Jan 6, 2007)

Don, the XRE has an isolated package because ceramic isn't electrically conductive. The metal pad on the bottom is just bonded to the ceramic to allow it to be soldered down. If you were to sand this off the bottom, you'd see the solid ceramic, and not a metal core/slug going to the esd/die/etc.


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## NewBie (Jan 6, 2007)

McGizmo said:


> Newbie,
> 
> Thanks for the point by point responses.
> 
> After Luxeon and Cree solder their dice to a ESD device, is the ESD device then soldered to the slug? I assume the answer is no in the case of the XR-E due to the isolation of slug to die.




I know for certain, that the CREE ESD device is soldered to the "slug" or the bottom ceramic that has a thin copper layer on it. The isolation comes from the ceramic layer in the "slug" or base.




McGizmo said:


> Is it possible that the bonding material used by Seoul in this assembly is up to its required task providing a proper bond is accomplished?




I figure you'd need to get long term testing data across multiple production runs and process tweaks the Seoul constantly does. IMHO, long term thermal cycling would be very important.




McGizmo said:


> Without speculating on the materials used and their ultimate viability and accepability in this application, there are a few things you observed which certainly point to a part that should be considered a reject. The obvious color shift with variation in Vf and the lack of uniformity of tint in viewing the die itself. This led you to taking the LED apart and your discovery of an incomplete and questionable bond layer.




Had I only binned it @ 350mA, I doubt I would have seen any issues at all. I've got five individual different parts, and they are not the same, but at least two of them are similiar, and one is a real performer and not one of the two.




McGizmo said:


> I believe there is speculation that this poor bond layer would put the die in a position of excessive heat and inadequate thermal relief when operated at specified drive levels. This would lead to poor lumen maintenance as well as color out of spec, presumably. Would this also likely be evident in flux output being below expectation?




Flux output is affected by a great many items, such as the root die, the phosphor layer, it's thickness and application, the electrical bonds, the bond wires, and such. If you had a part that was specified as a U bin, but it wasn't up to par, then I'd really be scratching my head over it.




McGizmo said:


> I have no idea how these LED's are made or what type of QC is present in the
> various plants. From the outside and with some experience with being sampled numerous times by Seoul, I will throw out some observations and comments of speculation more than anything else. It has seemed to me that Seoul have been very fast at taking a new die and packaging it for market evaluation/ acceptance. In the past, I have received a number of LED's which were pretty good but not up to market level; close but no cigar. It seemed that Seoul also recoginzed this and back they went and out came the next iteration.



IMHO, they have a bit more variation than a number of competitors, and constant process tweaking, so it is hard to say what is final. 




McGizmo said:


> I received a sample from them a few months ago that looked like a Nichia ceramic square box (jupiter style) but with the gull wing lead frames like the Luxeon. This LED had the flux of the XR-E and I believe it was host to the EZ1000 chip. The LED had a large phosphor dome for lack of better description and it may have been viable for fixed lighting but the light image or object was way to large for consideration of collimation. It seemed that Seoul now had the flux to compete but not the color consistency or image size. About a month later, the P4 shows up.
> 
> So I too have been given the impression that Seoul has been under an accelerated chain of trial and error and numerous new designs in an attempt to get to market level for acceptance. Tint variations aside, I believe the P4 has now brought Seoul to the forefront and in some applications to the lead. In their rush to get there, have they brought a flawed design with them or have they not dotted their I's and crossed their T's with the intent of first checking the market acceptance and viability of this latest itteration? :thinking: :shrug:



Hard to say, without long term testing of a large sampling of multiple production runs, IMHO.




McGizmo said:


> If this P4 assembly is sound with proper compliance to procedure in assembly and manufacture, that is one thing and likely something they can fine tune if they can rest on the design for a while. They can go back and dot the I's and cross the T's I would think.
> 
> Since I haven't experienced first hand a "dud" like this one here but I have experienced numerous exceptional performers which do not have tint shift as a function of Vf change, I am real impressed with the P4. The LED does perform admirably! I do not know if the design is sound when manufacturing is in compliance nor what to expect if manufacturing is not in compliance.



Thats a real can of worms, and hard to say. I could very easily believe you got a real awesome batch of parts, but it is hard to say if every batch will be like this.




McGizmo said:


> The Luxeon V was found to have problems and it seems the design itself was weak as the part never got past "portable" applications standards.



Yes, I talked about that earlier in the thread.




McGizmo said:


> Ultimately in the case of the P4, where will it end up being? Are the good parts not only good on first impression but built for some time to come? Given the impressive efficacy of the P4 and its claimed low thermal resistance, it would seem that it should and could be a part that procduces light and adequately dispells its excess in heat. A 90 lumen/ watt part is not saddled with a lot of thermal energy it needs to dissipate. Even this obviously bunk part reviewed here was not a case of instant death or catestrophic failure. We don't know for certain that this blue boy wouldn't have limped on with its blue output for a good number of hours, do we? If the die in this part did not exceed its specified opperating temperature as a result of incomplete bond it may well have held on, yes?



It wasn't the die that was the issue, so obviously, yes, if had been bonded properly, it might worked like one expected. Keep in mind, I'm looking at a variety of performers here, with different characteristics in the same batch.

Once you get delamination started, typically it progresses with time, and expecially with each change in temperature.




McGizmo said:


> A poor bond is a poor bond and no two ways about it. If the bond were proper and complete, would it be considered appropriate? It is really a shame that this "dud" wasn't tested for flux. I wonder if the part would be capable of high flux with its flawed assembly in the first place. Can you get a U bin flux part with a voided die bond, I wonder?



One would have to do many months to years of testing, across multiple batches, with a large number of samples to prove the technique is viable. Obviously, the part was tested for flux at the factory, being a 6500K W42180 T bin.




McGizmo said:


> We have seen a bad apple here but what does that tell us about the good apples?
> 
> This LED had an obvious birth defect and one that was seen immediately. Do we know the ramifications of this defect and can we assume a life expectancy for it as a result? Because it had an obvious defect, does this imply that others will have the same defect but not be obvious?



One would have to run the testing I mentioned before, especially if you want to know the long term reliability.

Some companies get deep into the materials, the material suppliers, and the processes of the parts they purchase for their designs, requiring notification of any changes, and specifically what was done. These sorts of changes often lead to problems after the company that is using the parts had ran their system and those parts thru qualification. I've seen it happen too many times to count on all my appendages.

Had I had one part that was an anomally, and four others that were close to the same, I'd definitely be a little less concerned.

As it stands, IMHO, I'd personally be *quite* anxious to do a lot of qualification testing on the Seoul P4, getting with the manufacturer to assure they will not change anything whatsoever over my expected production period, and get it in writing and signed by the president. That way, I'd be qualifying the parts I plan on using for production.

However, with some companies, you will find they keep sending you samples to re-qualify every 3 to 6 months (after the part is in production), so it makes it hard to do any sort of reliability testing, without a lot of real in depth analysis by some high zoot, highly specialized folks, with lots of experience in this sort of thing.


Anyhow, that is typical of life on the bleeding edge of things...


.


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## McGizmo (Jan 6, 2007)

Thanks Newbie.

Isaac,
Yes, I understand. Do we know how the die/ ESD device is bonded to the ceramic and how the ceramic is bonded to the sink? The point I should be more specific on I guess is is it practice to use epoxy in any of these "laminate" constructs? On dome XR-E's that I have sheard apart, I see a green material which I assume is some type of bonding adhesive, whether it's an epoxy or not, I have no idea. 

In Newbie's defect here, I am convinced that the bond layer was flawed but that doesn't tell me that the bonding material is inappropriate nor does it tell me that the design where such a bond is used is flawed. Without knowing the properties of the adhesive used, can we fault it because it was not applied properly in this case?

Now I am not inclined to take apart a perfectly functioning P4 to see if it in fact has similar voids in its bond. How many parts could I end up taking apart and see no such voids and yet they could still be there in some small percentage?!?! Maybe? :thinking: :shrug:

This part here that is obviously flawed was also obviously suspect in its behavior when Newbie fired it up. I have had obviously flawed Luxeons and set them aside. Does the obvious in this case imply a concern for the not so obvious?

Seoul in the past has tweaked their parts, IMHO, to get a contender to the starting line. Now that they do have a contender, IMHO, is it possible that further tweaking will be done if andonly if it is known to be an improvement? We have to wonder if they are aware of these defects like Newbie has found and we have to wonder if they are inclined to strive towards a part that can and will be dependable. Is the P4, in the majority at least dependable now? They brought us the part before the specs it seems to me. Has maximum drive current been updated from the TBD status that I have seen? 

I agree that these parts are at the bleeding edge. What remains to be seen is how much blood will be let and will the edge smooth out with traffic to the point it no longer cuts?



Ironically, the hours I have spent on this thread and topic could have been spent at the bench where I am modifying heads and reflectors to host the P4 as well as building them. :green: I guess I am out here on the thin ice and I might as well get in some play time while it holds?


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## 3rd_shift (Jan 6, 2007)

Usually with a mass production, if one apple is bad, there are likely others that have issues too since all were made pretty much the same way.
This is why there are sometimes product recalls.
Hopefully production of Newbie's bad one was very limited.
But it does make one wonder how many were made like that one before SSC quality control caught the problem and fixed it.


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## NewBie (Jan 6, 2007)

McGizmo said:


> Thanks Newbie.
> 
> Isaac,
> Yes, I understand. Do we know how the die/ ESD device is bonded to the ceramic and how the ceramic is bonded to the sink? The point I should be more specific on I guess is is it practice to use epoxy in any of these "laminate" constructs? On dome XR-E's that I have sheard apart, I see a green material which I assume is some type of bonding adhesive, whether it's an epoxy or not, I have no idea.




This is from the other thread: 








The square hole in the thermal pad copper:






The electrical via on the electrical connection pad ends:






The green is over the copper, and between the electrical pads and the isolated thermal patch on the backside of the LED. The green is often called solder mask, and is put over copper to prevent oxidization, and between the traces to prevent tree growth.


Here is a great photo by Anglepoise:






The XR-E ESD diode is directly soldered to the copper, much like this XR7090 shown here:







The copper is not epoxied to the ceramic, I've looked at that before. It looks like some direct thermal bond, or growth right on the substrate.




McGizmo said:


> In Newbie's defect here, I am convinced that the bond layer was flawed but that doesn't tell me that the bonding material is inappropriate nor does it tell me that the design where such a bond is used is flawed. Without knowing the properties of the adhesive used, can we fault it because it was not applied properly in this case?



That is the million dollar question. Infant failures in adhesives are also often signs of later long term failures.




McGizmo said:


> Now I am not inclined to take apart a perfectly functioning P4 to see if it in fact has similar voids in its bond. How many parts could I end up taking apart and see no such voids and yet they could still be there in some small percentage?!?! Maybe? :thinking: :shrug:
> 
> This part here that is obviously flawed was also obviously suspect in its behavior when Newbie fired it up. I have had obviously flawed Luxeons and set them aside. Does the obvious in this case imply a concern for the not so obvious?
> 
> Seoul in the past has tweaked their parts, IMHO, to get a contender to the starting line. Now that they do have a contender, IMHO, is it possible that further tweaking will be done if andonly if it is known to be an improvement? We have to wonder if they are aware of these defects like Newbie has found and we have to wonder if they are inclined to strive towards a part that can and will be dependable. Is the P4, in the majority at least dependable now? They brought us the part before the specs it seems to me. Has maximum drive current been updated from the TBD status that I have seen?



Since links for you are broken like you mentioned above I'll give a link for everyone else, and a page from the November datasheet for you:
http://www.seoulsemicon.co.kr/_homepage/home_kor/product/spec/W42180.pdf

http://www.molalla.net/~leeper/seoulp4.png[img]


[QUOTE=McGizmo]
I agree that these parts are at the bleeding edge. What remains to be seen is how much blood will be let and will the edge smooth out with traffic to the point it no longer cuts?

:popcorn:

Ironically, the hours I have spent on this thread and topic could have been spent at the bench where I am modifying heads and reflectors to host the P4 as well as building them. :green: I guess I am out here on the thin ice and I might as well get in some play time while it holds? :)[/QUOTE]

Hopefully your ventures into new territory will result in some real winners for you. I just got a package from dat2zip with another source of production arts for the Seoul P4 (thanks a million!). I need to run down and get some more 0.165" copper sheet metal for thermal epoxying these to, so I can get some testing done.


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## Beamhead (Jan 7, 2007)

I just tonight saw an Aleph A2 with a SSC P4 on a Nexgen driven at 750mA and it was very nice, the tint was slightly warm and the output was fine. Hopefully this an example of the U binned production units. I know that I trust the gentlemen/lady who will be using them to make sure no one gets stuck with a blueish/purple pos.

I have no doubt that the results Newbie is seeing are real and his info correct, but I _*personally*_ hope this all works out, for all involved. Back under my rock.


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## McGizmo (Jan 7, 2007)

Hi Newbie,

I just built a hand full of PD heads up using the P4's and was giving this issue futher thought while soldering. (At 25 mA and 525 mA, none of these exhibited any blatant color shifts and since these are V0 tint, they appear warm and low in color temp at both levels). I will be putting together some 27ST heads later on and I would expect that if I am going to see some tint shifts, the 917 mA high level will be more apt to bring this out.)

It is one thing to consider or identify a delamination or infant failure in a bond layer. I believe it is an altogether different thing to consider if the bond layer was voided or improper from inception and not a case of delamination. In the marine industry and around related composites not to mention some of my own successes as well as failures, I have seen delaminations and substrate failure due to poor design, poor prep and application and of course dueto forces beyond the intended design's parameters.

Is there any indication here with this sample that the void was a result of some thermo dynamic force or stress after assembly? Is it possible that the auto goo dispenser had an air bubble or farted when it came to this part? (Like those technical terms?  ) Is the void area actually a case of delamination or is it possibly a a case of inadequate bond material application?

When you took this LED apart, as I understand it, it had been functioning in a consistent, albiet unacceptable fashion and this is based on tint and tint shift. There wer no thermal observations made nor was the flux monitored. We have no idea, as I gather, whether the die was being subjected to temperatures beyond those specified by Cree. As I understand it, voltage and temperature are the two things that will damage the die itself. Temperature and humidity I understand are the primary hazards faced by the phosphor and probably the packaging itself, yes? The part itself was blue and annoyingly so and inconsistently so but was it or any of its constituents at "red line"?

Correct me please if I am wrong or clarify where I am off on the wrong track. This part was not autopsied after its death or catestrophic failure. Although young and no idea of how its flaws or deformity would effect its behavior or performance, in thelong run, it was taken apart because of obvious flaws and anomolies. The postmortem showed a section of void in its thermal bond layer. This would obviously put a local thermal stress on the die where it was not being directly relieved but could the die have survived regardless? It is easy for me to suppose that lumen maintenance would have been shortened with this part but I am not clear that it would have had a catestrophic failure or premature and sudden death?!?! 

If the void were indication of a delamination in process, I would be very concerned and question the design. If the void were a result of flawed bonding material application then my concern would be directed at QC and the assembly procedure; one much easier addressed and rectified, Iwould suppose.

I will continue to keep my eyes out for anomolies while I work with these parts but I will continue to work with them.  They really do have a lot going for them or so it seems to me so far! I have only worked with a small number of these but it is still greater than the 4 you have looked at. Neither of us are really in a position to extrapolate across the whole population unless it is based on something we know for certain is common among all. A faulty design could be such a consideration of course. 

I have only measured 3 of these P4's in my integrating sphere but all three have exceeded the flux I measured from the couple XR-E lights that I built with similar reflectors and drive currents. This is not enough to draw conclusions from to be very sure but it is enough for me to consider these LED's as viable and worth working with!!! With this much light output, they can't be generating excessive heat, relative to their peers. :shrug:


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## SemiMan (Jan 7, 2007)

I dug up a presentation I was given on the Lumileds K2 a while back. Interesting to note, they changed the method of assembly between and Lux3 and the K2.

In the Lux3, the die is soldered to the submount and then the submount is soldered to the base. In the K2, the die is thermosonically welded it looks like to the submount, and the submount is soldered to the base.

Semiman


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## NewBie (Jan 7, 2007)

I just got production Seoul P4 U bin parts from dat2zip for testing, this one shown here is #1.

I briefly ran the current up to 1 Amp, and unlike the other production batch I got, it is *very* much improved to say the least! I know Seoul has a lot of variation from past experience, but I would have never believed they could be so night and day from one batch to another. But I will let the testing speak for itself, which I'm getting ready to start.


Anyhow, the test rig:


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## EngrPaul (Jan 7, 2007)

As anticipated


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## 3rd_shift (Jan 7, 2007)

Now, this should be quite interesting.


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## NewBie (Jan 7, 2007)

Okay, collecting data takes awhile, to write down, and then type into Excel.

Sorry for the two hour delay.

I took one of my Seoul P4 T bins and also ran the data.

First, here is the Vf comparision chart:







Here is the intensity graph vs. current for three of them:


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## 3rd_shift (Jan 7, 2007)

So, even the "T" flux rated SSC led is still doing pretty good then?
Not too much variation there.
Almost makes me want to make the "will call" trip to mouser electronics nearby to try a few myself.


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## NewBie (Jan 7, 2007)

3rd Shift

It appears there is not that much difference between the T and U bins of the ones I've tested here, you are correct- the numbers for the ones that were tested, @ 1A is a difference of 8.65%, from the T bin to the top U bin.

However, if you were to set the light up for a specific brightness output, it could gain you 9% more runtime, and 9% less heat. If you set them up for the same current, I highly doubt anyone could actually see the 9% difference in brightness.

Here is a sideview shot on a wall, of the Seoul P4 U bin #2 from Dat2zip, about 2 feet from wall:


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## NewBie (Jan 7, 2007)

Here are some bracketed close in shots against a piece of paper nearby. I had my wife compare the screen shots to the paper shots, while I did them, to make things as realistic as possible:

















Here I put a piece of paper with a small hole in it, to assure I wasn't getting any tinting off the copper heatsink from stray light:


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## ViReN (Jan 8, 2007)

NewBie said:


> I just got production Seoul P4 U bin parts from dat2zip for testing, this one shown here is #1.
> 
> I briefly ran the current up to 1 Amp, and unlike the other production batch I got, it is *very* much improved to say the least! I know Seoul has a lot of variation from past experience, but I would have never believed they could be so night and day from one batch to another. But I will let the testing speak for itself, which I'm getting ready to start.
> 
> ...





>



Hello NewBie, it's an excellent setup, so in test currents ranging from 0 - 1A the die temprature is kept at 25 degree celcius? (like they mention in datasheet) ....
Is your wall having gradient color or the LED has that tint variation? or there is yellow at edges and Blue in center... (like old generatin 5mm LED's ?)


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## ViReN (Jan 8, 2007)

>


isn't the Cree better of the two (having lower vf?)



>



how does intensity compare with Orignal Cree P4 bin?


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## NewBie (Jan 8, 2007)

ViReN said:


> Hello NewBie, it's an excellent setup, so in test currents ranging from 0 - 1A the die temprature is kept at 25 degree celcius? (like they mention in datasheet) ....
> 
> Is your wall having gradient color or the LED has that tint variation? or there is yellow at edges and Blue in center... (like old generatin 5mm LED's ?)



No, the die isn't at 25C, but the slug is pretty close.

That is the LED, lol, not my wall changing tint!

Go back and look again, I just updated the post with pictures on a piece of paper about 1" or so away.

Here is a bracketed set of shots from a bumpy reflector, of the U bin I got from Dat2zip, this is #2:

















The tint shift on this U bin Seoul P4 from Dat2zip is *vastly* improved over different current levels, watch the movie of #2:

http://www.molalla.net/~leeper/2sp4ud2z.wmv

A shot of the U bin die @ 1A:


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## Hellbore (Jan 8, 2007)

NewBie said:


> No, the die isn't at 25C, but the slug is pretty close.
> 
> That is the LED, lol, not my wall changing tint!



Admit it, you painted your wall with a gradient just to trick us!


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## shiftd (Jan 8, 2007)

looking good Jar,

Now, we need to get the LED from this batch, not from your T batches !!


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## NewBie (Jan 8, 2007)

Sorry, wish I had.

Anyhow, here are some side profiles of the U bin Seoul P4 LED #2 in a bumpy reflector, bracketed:


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## IsaacHayes (Jan 8, 2007)

Well it doesn't seem to really shift colors at all. It still has some blotchy-ness to the beam, but previous ZLED's had that too.

Let's hope the stinkers you got were only a certain lot #, and won't show up ever again in other batches!


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## McGizmo (Jan 8, 2007)

Newbie,

Your sample #1 came from the same reel that I have been building with. I don't see any beam images from it but I would expect them to be warmer in color temp from what you have shown on #2. I assembled 18 of these in 27ST heads tonight and all were very close in tint and no noticible change to my tired eyes from the low to high output levels. :shrug:


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## chris_m (Jan 8, 2007)

NewBie said:


> It appears there is not that much difference between the T and U bins of the ones I've tested here, you are correct- the numbers for the ones that were tested, @ 1A is a difference of 8.65%, from the T bin to the top U bin.



Which is exactly what you'd expect given expected practice of making them all the same way and then picking off the parts which make the higher bin. Suggests the consistency of production is pretty good (at least for that limited sample). Presumably U bins are all towards the bottom end of the bin (though still possibly 95lm at 350mA), and T bins towards the top, in which case the T bins are pretty good value for a ~90lm at 350mA part.


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## NewBie (Jan 8, 2007)

chris_m said:


> Which is exactly what you'd expect given expected practice of making them all the same way and then picking off the parts which make the higher bin. Suggests the consistency of production is pretty good (at least for that limited sample). Presumably U bins are all towards the bottom end of the bin (though still possibly 95lm at 350mA), and T bins towards the top, in which case the T bins are pretty good value for a ~90lm at 350mA part.




For brightness consistency, yes, in other areas, not really, which has been shown earlier. I'm at least very glad to see these two don't move much in color from 400mA to 1000mA, like several of the others obviously did. 

For tint in the different areas of the beam, I'm not seeing a major improvement like I was also really hoping for- for the white wall warrior type. I believe some of this could be mitigated by reflector shape, depth, and textured or jeweled reflectors.

The differences in the new graphs I made for the Vf and the curve shapes is interesting, as shown in the earlier graphs, and I am still wondering what is going on there. Normally I just see offsets with the CREE, but the shape is the same. It could be resistance, and variation in thermal transfer, especially for the shape- but I'm speculating there. From the limited sample, it is hard to say.

I've got more parts from other supply points comming still, it will be very interesting to see how it all pans out.


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## EngrPaul (Jan 8, 2007)

I'd love to see a relative brightness graph including the Cree XR-E


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## ViReN (Jan 8, 2007)

I just seen the updated post... but... isn't it still very bad as compared with Cree... Cree's are excellent that way.

and to even out the tint variation, i think heavy peel reflector like you have used is very nice that way.... it's kind of fooling LED for it's tint variation...

in the pictures of #163 (if that is a vast improvement)... i wonder what would have been the orignal Seoul LED :sigh: beause i still can see "Blue" on upper left corner...

Which flashlights are going to use this led?.... hope cheaper ones... and not the expensive ones...

I mean you know how people have complained the rings of P1D CE..... imagine this tint shifter LED in anything above $30.... and people will ... :touche: with the manufacturer...


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## Outdoors Fanatic (Jan 8, 2007)

Can someone please come up with a KISS explanation about the P4 Seoul VS Cree XR-E?


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## Anglepoise (Jan 8, 2007)

The way I understand all this is as follows.

First you must decide which of these best describes you.

1: "I buy finished flashlights from dealers or manufacturers. I do not own a 
soldering iron."

2: "I buy emitters and mod these to existing flashlights I own. I understand 
binning and how Vf fits in."

If beam quality and colour tint are important to you, and you are a number 1 above, then stick with LUX III lights until everything settles down.

If you are a number 2, then experiment away but be careful with what emitters you buy. High Vf and poor tint examples ( and it looks like we will see lots) will not be destroyed and will finish up on Buy ,Sell and Trade. 
So if buying in ones and two's, take care.


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## McGizmo (Jan 8, 2007)

It seems we are moving away from the scope of the problem as may be indicated by one bad apple. No worries.

Like I have stated before, I don't think ghe XR-E or the Seoul P4 can win a white wall contest against a Luxeon. If the contest is based up on a test where flux or lux come into play, the story changes significantly. If the contest is based on equal output but lets look at duration of illumination, the story changes.

If you want to maximize lux with a reflector of typical size, the Seoul will take the line honors over the XR-E. If you use a TIR optic designed specifically for each LED, I would suspect the XR-E to edge out the Seoul P4 in a lux contest but don't know that for certain. 

If you want good flux in the spot but are looking to get more flux in the spill portion of the beam, the XR-E's viewing angle can be exploited with good effect.

In terms of construction of the LED itself, I really like the XR-E. Surface mount with neutral sink slug is great. Ceramic package is great. Metal dome retension is great and glass dome is excellent. All IMHO. All contact surfaces of the XR-E can be used to aid in heat removal; very nice!!!

The Seoul P4 has a lower thermal resistance. For some this is a big deal!! 

The EZ1000 die at this point is about efficacy and the shear volume or quantity of light it produces and not as much about the quality of the light produced. I personally consider the quality of light more than adequate and the abundance of photons per watt a real boon where one is given alternatives not previously available.

To relegate the Seoul P4 to cheap or disposable lights is a blunt denial of what its potential can provide,IMHO.

It seems this thread is headed towards the white walls and white halls. No problem, but I suggest the P4 is better suited for the real world and outdoors. :shrug:


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## milkyspit (Jan 8, 2007)

Okay, I'll readily admit that I've lost track of this thread in recent posts, though I had read through the first 100 or so diligently. Good stuff as usual, Newbie, and plenty of food for thought. Thanks all!



As to the utility of the SSC P4, I'll side with Don here... been playing with a couple myself, most intriguingly in a humble Nuwai Q3 host... and I find this light plenty useful. In fact, more than once I've stashed it in my pocket on the way out the door, for the trek across the yard to our detached garage... no complaints about the tint or color uniformity with that sort of mission... I either got VERY lucky in the SSC lottery, or these emitters aren't half bad. They have neither the tint-selection granularity of the Luxeons nor the brute-force straight ahead photon pumpage of the Cree, but they do occupy IMHO a useful place in the upcoming crop of LED lights.

Also puts a third player in the field, giving Lumileds some additional competition. That can only be a good thing.


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## Hellbore (Jan 8, 2007)

Would one of these make a good upgrade to a MagLED 3D bulb replacement unit? I have one ordered I was thinking of using for that purpose, if it would be noticeably brighter or longer runtime than the Lux III that came with the MagLED.


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## milkyspit (Jan 8, 2007)

Hellbore said:


> Would one of these make a good upgrade to a MagLED 3D bulb replacement unit? I have one ordered I was thinking of using for that purpose, if it would be noticeably brighter or longer runtime than the Lux III that came with the MagLED.



Runtime probably about the same, output probably higher.


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## McGizmo (Jan 8, 2007)

milkyspit said:


> Runtime probably about the same, output *probably* higher.



*Probably*?!? (emphasis mine)

I think you guys are maybe not considering the flux from these LED's? 

I set up my integrating sphere and computer to measure a set of 27ST heads I just assembled as I wanted to see if there were any real and measurable discrepencies from what my eyes had told me weren't there. All of these (18 of them) ranged from the runt at 135 lumens to a couple that just cleared 150 lumens. Most were in the low to mid 140's. The 27 heads seem to measure within a few percentage points of _real_ lumens.

Out of curiousity, while I had the IS set up, I decided to measure a L1 mod that had had a lux III and now has a P4 in it (behind a McR-18 that got modded). 

For a very rough comparison, this dumb head is compared to a dumb head with Luxeon and same style reflector: (I did use same L1 pak so drive current should be same.

Luxeon L1 Lux - 860, lumens - 33
Seoul P4 Lux - 2200, lumens - 101

Now my IS is overly optimistic by about 15% when it comes to measuring these 1" OD lights so the lumen measures should be reduced accordingly. 

Regardless, disregard the P4 if you want! :nana:

Time will tell.....


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## chris_m (Jan 8, 2007)

chris_m said:


> Presumably U bins are all towards the bottom end of the bin (though still possibly 95lm at 350mA), and T bins towards the top, in which case the T bins are pretty good value for a ~90lm at 350mA part.



Further to these thoughts, assuming the binning is accurate, ISTM that a SSC T bin which is available is actually likely to give more lumens than a Cree Q2 bin (87-93lm) which isn't available yet, and when it does appear is likely to be towards the bottom of that range (working on the theory that given the delays on this part, they are struggling to meet the specs for it). Also an SSC U bin, which is available to some and will presumably get a wider release soon gives almost as many lumens as a Cree Q3, which is extremely unobtanium.

Am I missing something with these thoughts, or do other characteristics of the Cree (such as tint consistency - though not convinced that's a real world issue for those of us who aren't white wall hunters) make up for this?


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## hotbeam (Jan 8, 2007)

Good stuff Don! I could live with those lumens!! EASILY. Was that driven at 500mA? 



McGizmo said:


> *Probably*?!? (emphasis mine)
> 
> I think you guys are maybe not considering the flux from these LED's?
> 
> I set up my integrating sphere and computer to measure a set of 27ST heads I just assembled as I wanted to see if there were any real and measurable discrepencies from what my eyes had told me weren't there. All of these (18 of them) ranged from the runt at 135 lumens to a couple that just cleared 150 lumens. Most were in the low to mid 140's. The 27 heads seem to measure within a few percentage points of _real_ lumens.


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## cy (Jan 8, 2007)

for some applications like Stenlight, emitters are mounted on an integrated board. Cree's are not an option without redesigning entire board.


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## NewBie (Jan 8, 2007)

McGizmo said:


> It seems we are moving away from the scope of the problem as may be indicated by one bad apple. No worries.



It was one really bad apple, two questionable apples, one decent apple, and one stellar apple. Both of dat2zip's apples were fine.

I'm hoping this sort of thing doesn't become a batch to batch situation, so far, it is looking like it, future samples will tell us more.




McGizmo said:


> If you want to maximize lux with a reflector of typical size, the Seoul will take the line honors over the XR-E. If you use a TIR optic designed specifically for each LED, I would suspect the XR-E to edge out the Seoul P4 in a lux contest but don't know that for certain.



I'd agree, as the P4 has more flux going sideways, to get directed by the reflector. Lux is a hotspot measurement. Curious, have you done any lumens testing with equal thermal situations on the P4 vs. XR-E?



McGizmo said:


> Like I have stated before, I don't think ghe XR-E or the Seoul P4 can win a white wall contest against a Luxeon.



Personally, the P4 reminds me a lot more of the older Nichia products, like their Jupiter, as far as tint vs. angle.




McGizmo said:


> If you want good flux in the spot but are looking to get more flux in the spill portion of the beam, the XR-E's viewing angle can be exploited with good effect.
> 
> In terms of construction of the LED itself, I really like the XR-E. Surface mount with neutral sink slug is great. Ceramic package is great. Metal dome retension is great and glass dome is excellent. All IMHO. All contact surfaces of the XR-E can be used to aid in heat removal; very nice!!!
> 
> ...



At this point the sheer output of CREE's EZ1000 used in the Seoul P4 and the CREE XR-E is a really big deal, IMHO. With LumiLEDs having patented the three best phosphor application methods (so far) for uniform tint, it is unfortunate that other manufacturers are cut off. Combining it with the rough textured reflectors that the hotwire crowd created to get rid of filament images, however, does go a long way towards helping to blend contrasting tints.




McGizmo said:


> To relegate the Seoul P4 to cheap or disposable lights is a blunt denial of what its potential can provide,IMHO.
> 
> It seems this thread is headed towards the white walls and white halls. No problem, but I suggest the P4 is better suited for the real world and outdoors. :shrug:



Running LEDs over current, to look at tint shift, as well as white walls (since we very obviously have a major white wall crowd presence here on CPF- e.g. Fenix P1D-CE/Lumapower/Huntlight thrashing), not looking at this aspect and not disclosing it would be doing those folks a big dis-service. It is a very important aspect for this crowd.

Out of doors comparisons are better done with flashlight running at the same input power and also with the same reflectors. Often these lights are each customized to take advantage of different aspects to achieve a certain goal. IMHO, due to this, these sorts of comparisons are best left at the flashlight level, especially since additional factors come into play, such as the system thermal solution and such.

On a side note:
I did find some white wall shots I did on the CREE XR-E utilizing the same camera, for comparison, over in this thread, about post 57 (and there are now plenty of other XR-E beamshots from various lights on CPF now):
http://candlepowerforums.com/vb/showthread.php?t=138503&page=2&pp=40




McGizmo said:


> I think you guys are maybe not considering the flux from these LED's?
> 
> I set up my integrating sphere and computer to measure a set of 27ST heads I just assembled as I wanted to see if there were any real and measurable discrepencies from what my eyes had told me weren't there. All of these (18 of them) ranged from the runt at 135 lumens to a couple that just cleared 150 lumens. Most were in the low to mid 140's. The 27 heads seem to measure within a few percentage points of _real_ lumens.
> 
> ...



Since the Luxeons come in a very wide range of Lumen bins, care to mention what bin LED was used for this Lumens (very different than lux- though I'd be willing the lux was also higher) comparison? 

Color bin also comes into considerable play when measuring Lumens, any idea what was used there?

Have you had a chance to do the same sort of thing with any of your XR-E LEDs and your integrating sphere?


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## ViReN (Jan 8, 2007)

McGizmo said:


> *<SNIP>*
> 
> Luxeon L1 Lux - 860, lumens - 33
> Seoul P4 Lux - 2200, lumens - 101
> <*SNIP*>



Nichia = Banana
Luxeon = Orange
Seoul P4 = Granny Smith Apple
Cree XR-E = Royal Gala Apple

for more apple types *click here* and *Here* :nana:

shouldn't we compare apple - apple here?


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## ViReN (Jan 8, 2007)

NewBie, I just viewed sp4 videos... looking at them, I found one very nice application for SP4 LED's  .... a MultiColor (white-Blue) sp4 tintshifter 'torch' speciall applications if you overdrive, blue color will help find blood stains easily, drive within limits, you are safe 

(requesting permission: can i download _all videos_ available at this location?)


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## milkyspit (Jan 8, 2007)

McGizmo said:


> *Probably*?!? (emphasis mine)




Uh, Don? I was making a comment more on the capabilities and/or weirdness of the driver circuit, not the emitter itself.


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## McGizmo (Jan 9, 2007)

Milkyspit,
My bad. I didn't realize the Mag driver would be erattic with a different LED.

Newbie,

Most of the Cree XR-E LED's coupled with the 27 mm reflector were in Ti XR27 heads and the drive current was less than these 27ST'w (525 mA VS 917) I only have two Cree XR-E lights with the DB 917 and they both measured in the low 130 lumen range. 

On any of these tests I am not leaving the light on for a half hour to reach steady state temperature.

My position on the white wall was and still remains that if it is of major import, the answer is simple. Stick with a Luxeon. The lottery is still alive there but it is a lottery much beter understood.

If you care to answer any of my questions regarding the obviously flawed and somewhat flawed LED's of your first batch and how these flaws might be considered to either show up later on in seemingly good LED's or get progressively worse in any of them it would be appreciated. gain though, it's no big deal to me. I will work with good LED's if I have them and become concerned about them not remaining good if I can be given reason to assume that concern.

ViRen and Newbie,

The example of the mod of the L1 was just that, an example. I brought that up as simply an illustration where one could take a light that is a good light currently sporting a Luxeon. It was a rather simple and straight forward mod to replace the Luxeon with a Seoul P4. I have no idea what the bin was in the L1 but it was replaced with a U bin P4. 

ViRen,
The rule is to attack the post and not the poster. I try to abide by that rule and realize the value in not attacking anything unless there is a really good reason to do so. I have no desire to attack you. One of these days though, I may very well attackone of your posts with a vengence!! :nana:

HotBeam,

Those lumen measures were at approximately 917 mA of current. They are also net measures out the front of the light that has a deep reflector that isn't hubble telescope quality in reflective finish and through 2 mm of sapphire window that does not have unobtanium A/R coating on both sides and edge. 30% transmission loss maybe? :shrug:


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## ViReN (Jan 9, 2007)

> ViRen,
> The rule is to attack the post and not the poster. I try to abide by that rule and realize the value in not attacking anything unless there is a really good reason to do so. I have no desire to attack you. One of these days though, I may very well attackone of your posts with a vengence!! :nana:




i am sorry, my intent was not to attack you in any way. Please forgive me if you have felt offended/attacked in any way.

What i actually meant was; would it not be nice to compare cree - cree based LED's instead of cree - luxeon, since this thread is about Cree-die based Seoul P4 LED discussion.

I fully agree with you that it is relatively much easier to mod a Luxeon light with Seoul P4 LED and get advantage of Cree die and Lot's o Lumens efficiently (barring the tint issues).... structure of Luxeon and Seoul P4 being nearly same with slight differences in dimensions and position of die as compared with Luxeon - Cree XR-E

Once again, please accept my apologies; if i have offended / attacked you in any way, it was un-intentional. please suggest if you would like me to remove/modify my comments, i would be glad to do so.

//Sorry I had to look at dictionary for meaning of vengence:::vengeance


----------



## McGizmo (Jan 9, 2007)

ViRen,
You did not attack me and no need to apologize. Some of your comments insult my intelligence or what little gray matter I chose to assume is intelligence and it is them that I may take a shot at one of these days.

See, I just put some of these P4's in some titanium heads that will go on lights that will sell for $440. I don't really feel any need to defend these lights or my election to use P4's in them. The lights themselves will speak for themselves and succeed or fail on their own accord. I do plan to caution folks that the P4 is not a white wall winner and there is likely some tint variation that they will see. I do believe in full disclosure even if it puts a dampner on the interest or sales. I have to decide if I need to alert folks to this thread here in particular or if I could just take choice quotes from it and include them in the disclosure. Such as:



> Which flashlights are going to use this led?.... hope cheaper ones... and not the expensive ones...



and



> IMHO, especially after looking at the construction methods, personally I don't think I will personally be using these, and if I did, I personally will not put them in any of my personal expensive flashlights. Maybe something like a Lumapower or a Nuwai Q3. For myself personally, I'd definitely be very tempted to run them at low powers (less than 350mA), and would not personally use them in anything I personally would want to last or personally count on. I personally would be very tempted to get as much heat as possible out of the LED.



Now there may be someone interested in buying one of the Ti lights I am making and that person may not have read this thread. Oh what to do?!?! :thinking: :shrug:


----------



## hotbeam (Jan 9, 2007)

McGizmo said:


> HotBeam,
> 
> Those lumen measures were at approximately 917 mA of current. They are also net measures out the front of the light that has a deep reflector that isn't hubble telescope quality in reflective finish and through 2 mm of sapphire window that does not have unobtanium A/R coating on both sides and edge. 30% transmission loss maybe? :shrug:



OK, lets say 145 forward lumens as a typical at 900mA. If we work on 10% loss from the glass, that makes 161lms at the LED! Very decent. 20% becomes 181lms. 30% loss becomes a whopping 207lms @ ~3w consumption!


----------



## NewBie (Jan 9, 2007)

McGizmo said:


> Milkyspit,
> My bad. I didn't realize the Mag driver would be erattic with a different LED.
> 
> Newbie,
> ...



I just finished testing some of these LEDs in a home made integrating box, and I'll be *damned* if I can see any difference between the best Seoul P4-T of five and a random CREE XR-E P3 (next one off the strip).

The U bin Seoul P4 dat2zip obviously measured 9% brighter than the T bin from what I measured. Are you attempting to compare a U bin Seoul with a lesser binned XR-E P3?

Don, your LEDs in our emails, you mentioned you were utilizing P3 bins for the CREE XR-E. Does this account for the minor differences you keep talking about? Which color bin of each were you using for the comparision (were they the same tint)?




McGizmo said:


> On any of these tests I am not leaving the light on for a half hour to reach steady state temperature.
> 
> My position on the white wall was and still remains that if it is of major import, the answer is simple. Stick with a Luxeon. The lottery is still alive there but it is a lottery much beter understood.
> 
> If you care to answer any of my questions regarding the obviously flawed and somewhat flawed LED's of your first batch and how these flaws might be considered to either show up later on in seemingly good LED's or get progressively worse in any of them it would be appreciated. gain though, it's no big deal to me. I will work with good LED's if I have them and become concerned about them not remaining good if I can be given reason to assume that concern.



Go back in the thread, and I already covered that, and I believe you thanked me.




McGizmo said:


> ViRen and Newbie,
> 
> The example of the mod of the L1 was just that, an example. I brought that up as simply an illustration where one could take a light that is a good light currently sporting a Luxeon. It was a rather simple and straight forward mod to replace the Luxeon with a Seoul P4. I have no idea what the bin was in the L1 but it was replaced with a U bin P4.



Okay, so are you saying that could have been comparing a Q brightness bin Luxeon I against a top end Seoul P4 U bin, who knows what the color tints were (makes a difference also)?




McGizmo said:


> I set up my integrating sphere and computer to measure a set of 27ST heads I just assembled as I wanted to see if there were any real and measurable discrepencies from what my eyes had told me weren't there. All of these (18 of them) ranged from the runt at 135 lumens to a couple that just cleared 150 lumens. Most were in the low to mid 140's. The 27 heads seem to measure within a few percentage points of _real_ lumens.





McGizmo said:


> HotBeam,
> 
> Those lumen measures were at approximately 917 mA of current. They are also net measures out the front of the light that has a deep reflector that isn't hubble telescope quality in reflective finish and through 2 mm of sapphire window that does not have unobtanium A/R coating on both sides and edge. 30% transmission loss maybe? :shrug:




30% loss for the reflector and 20% for the sapphire? So 50% loss total? 
Or is that 30% for the window and 30% for the reflector? (60% total)

So, are you saying your U bin Seoul P4 are making +260 lumens? 
And some of them are making +300 lumens?

Scratches head....do I look that gulliable? Or did I misunderstand you?

Because I certainly have not been able measure any differences between similarly binned Seoul and CREE parts...


The high losses of sapphire/mineral glass really showed up clearly in the Gransee testing of the HDS light, if you recall that. I think the measured impact was 14% or so there? How about 16% loss for sapphire/mineral glass?






.


----------



## Hellbore (Jan 9, 2007)

So is this better than the Osram Golden Dragon or Nichia Jupiter?


----------



## NewBie (Jan 9, 2007)

Better is a relative term. IMHO, each LED has it's own advantages and trade-offs.


----------



## NewBie (Jan 9, 2007)

Here is the link to the reflector loss testing:

http://candlepowerforums.com/vb/showthread.php?p=1779214#post1779214

Keep in mind with LEDs, less of the light is hitting the reflector than with an incandescent bulb, so you have less losses. I don't have time to look, but the 45% losses (65% bulb to flashlight output) was measured with UCL, which is much lower loss than sapphire/mineral glass.


----------



## Kiessling (Jan 9, 2007)

I'd be quite interested about some solid data for LED lights with our current reflectors and windows. This would help us tremendously to "guesstimate" the real luminous flux of a device.
bernie

P.S.: hey NewBie ... it's more like 35% loss ...


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## NewBie (Jan 9, 2007)

LOL, you are right, thats what I get for thinking right after the alarm clock goes off.

I believe the reflector losses drop to 25% with a luxeon output distribution (which would be lower for the CREE XR-E and similar to the luxeon for the Seoul), according to my simulation.

Toss in 17%-25% additional losses for sapphire (mineral glass), or use the actual tested 14% loss from the HDS lights in the integrating sphere.

Say 40%-45% overall losses with sapphire lens plus reflector losses for the Seoul and Luxeon?


----------



## EngrPaul (Jan 9, 2007)

How much for the dust on the gummy?


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## McGizmo (Jan 9, 2007)

Newbie,

For all I know, the L1 head has a P bin LuxI in it. This was a simple Before and After Mod and I provided bin information on the P4 because I have it. YMMV, obviously!!

In regards to the comparison of flux between the XR-E and the S-P4, I am not going to claim one is doing a better job than the other in getting the light out. I have no means of establishing such a claim nor do I think anyone does beyond Cree and Seoul in a combined effort. At best one could legitimately test two populations of these LED's and make a statement based on the results of these two populations but as to whether the to populations have dice of even potential, who knows.

I am making no claims or statements as to what the loss is in my reflector and window package beyond the obvious that there is loss there. I have no idea what the raw output of the LED itself is nor do I really care. I have LED's and reflectors and windows on hand and I am building with them. I find the results very satisfying and my crude means of some measurements supports this satisfaction. I threw out a 30% loss based on a ball park total absorption for the front end I am using. If that number is close and we take on average a 145 lumen output then I think this works out to 207 lumens raw at 917 mA. If my front end is more efficient then the raw flux is less. If my front end is worse than 30% in loss then the raw flux of the LED is even greater. :shrug:

These are flashlights here, nothing more and nothing less. Some are real expensive and one must consider the value VS the price. As a simpleton garage hacker, I take Seoul P4 and install in flashlight. I turn flashlight on and it is bright and to my perception, white. Cool. On to next flashlight. There is technology and wonder and black boxes involved in these lights but this is beyond my ken. This thread is about initial evaluation. I look forward to the in use evaluations; for those ready and willing to take the risks implied.


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## Gryloc (Jan 9, 2007)

Newbie, 

I have been watching this thread for a while, but I am still waiting for some good solid numbers I can compare with. Can you do the same old flux test that you did with the Cree XR-E a while back in your "Production CREE XR-E Testing" thread? You had a graph that showed flux ratings throughout 0-2000mA of current meassured in lumens (which were probably approximate, but very close). I understand that the SSC P4 cannot handle 2A, but it would be neat seeing what the thing can do compared to the XR-E. Maybe it can handle the 2A, even if the phosphors will degrade. I see you made a graph recently showing "relative brightness" of the P4, but how is it exactly set up and how would that be read? If the luminosity is measured in % intensity like the many data sheets by Lumileds and Cree, then why isnt the 100% at the 350mA mark? Maybe it is something completely different and I am asking the wrong questions, seeing that the line on the graph is very linear (which is odd).

I ordered a few more Crees, and I got one of the SSC P4s from Mouser (eek!). I just wanted to see some figures that I can make rough comparisons with to the XR-E and different Luxeons. I realize that the Cree may not be for me at this time because of the odd 70 degree radiation. I have been hoping to upgrade the old T-binned LuxIII's in my 'ol quad D-size Maglite with some LED that has the awesome Cree die. I surely would not mind having a 600+ lumen monster!  I think the P4 would best suit me currently because it can be used with the old IMS SO20XA reflectors, well hopefully. 

I also wanted to get a good idea what the EZ1000 die can do. I have distant dreams of using the dies in a special module that uses four of them on a ceramic slug with an even coat of phosphor (like the XR-E). I dream that just four of these special modules can be mounted on a special, water cooled copper slug that would make a direct replacement for automotive headlight bulbs. It would be a newer and better version than that old drawing I made a couple of years ago. My new version, using those incredible dies, will be much smallerand the image size (the light emitted) would better match the light bulb filiments that it will replace. There is still alot of stuff to consider, though. This thing can be made (probably easily too), but I just dont have any of the equipment and parts. I have been drawing these up on SolidWorks and I wish I can make or buy these.  Again, I am dreaming!

The old drawing, hosted by Robban, is right here (go to post #8): https://www.candlepowerforums.com/threads/107743

Sorry if I got way off topic from the original thread. I always have almost too many questions. Anyway, Thanks!


-Tony


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## EngrPaul (Jan 9, 2007)

McGizmo said:


> As a simpleton garage hacker, I take Seoul P4 and install in flashlight. I turn flashlight on and it is bright and to my perception, white. Cool. On to next flashlight.


 
The sandwich shoppe, without any fanfare I am aware of, began selling these U-bins! Many on the way to me 

My plan is to start with my cheapest lux flashlights and work my way up to the more expensive ones. If I am unhappy with the results, I'll just stop and take a step back. 

Hopefully, these flashlights will not need significant reflector modding, and will be ready for the next generation of emitters. The problem with the Cree mods I have done, is there is no going back.


----------



## NewBie (Jan 9, 2007)

Gryloc said:


> Newbie,
> 
> I have been watching this thread for a while, but I am still waiting for some good solid numbers I can compare with. Can you do the same old flux test that you did with the Cree XR-E a while back in your "Production CREE XR-E Testing" thread? You had a graph that showed flux ratings throughout 0-2000mA of current meassured in lumens (which were probably approximate, but very close). I understand that the SSC P4 cannot handle 2A, but it would be neat seeing what the thing can do compared to the XR-E. Maybe it can handle the 2A, even if the phosphors will degrade. I see you made a graph recently showing "relative brightness" of the P4, but how is it exactly set up and how would that be read? If the luminosity is measured in % intensity like the many data sheets by Lumileds and Cree, then why isnt the 100% at the 350mA mark? Maybe it is something completely different and I am asking the wrong questions, seeing that the line on the graph is very linear (which is odd).



I could have rescaled it, using 350mA as 100%, you could do the same as well.

I don't have access to equipment for measuring lumens very often, and have to pull favors. I've been considering purchasing my own NIST traceable reference standard so that I could get in the ballpark at home. I've also considered getting a diffraction grating and sweeping thru the spectrum, recording angle and intensity once refrence angles are established from neon, argon, etc. Or, possibly wiring up a linear 2048 cell CCD array. Somewhere around here I have a 256 cell linear array, but if you are going to put out the effort...

The CREE EZ1000 used in the Seoul P4 is a very nice die. It is not pushed at it's maximum, and the themal resistance in the CREE XR-E and the Seoul P4 are both lower than even the Luxeon K2. On the Seoul datasheet, they specify flux was done at 25 degrees C ambient, and give no other further details about their test conditions- and when LEDs heat up, their flux drops, so if they used an emitter mounted on a MCPCB with a 1" square heatsink, you'd obviously get lumen drop as things heated up. When I tested the Seoul P4, I was quite agressive with holding the slug temperature as close to ambient as possible. This was not available for other tests. So consider those factors. See picture below:








I just measured the temperature of the slug of the P4 after it has stabilized for many hours, it is at 23.9C @ 1.000A drive. The inlet air temperature to the air cooled heatsink is 23.1C. As a point of reference...




Gryloc said:


> I think the P4 would best suit me currently because it can be used with the old IMS SO20XA reflectors, well hopefully.



Some of those have a warped bottom, near the opening, and it helps to break up the tint of the P4 a bit, so you may be pleasantly surprised.




Gryloc said:


> I also wanted to get a good idea what the EZ1000 die can do. I have distant dreams of using the dies in a special module that uses four of them on a ceramic slug with an even coat of phosphor (like the XR-E). I dream that just four of these special modules can be mounted on a special, water cooled copper slug that would make a direct replacement for automotive headlight bulbs. It would be a newer and better version than that old drawing I made a couple of years ago. My new version, using those incredible dies, will be much smallerand the image size (the light emitted) would better match the light bulb filiments that it will replace. There is still alot of stuff to consider, though. This thing can be made (probably easily too), but I just dont have any of the equipment and parts. I have been drawing these up on SolidWorks and I wish I can make or buy these.  Again, I am dreaming!
> 
> The old drawing, hosted by Robban, is right here (go to post #8): https://www.candlepowerforums.com/threads/107743
> 
> ...



For some folks, punching lumens down range is important, others like more balance between beam and flood, others want a perfect looking beam, some want longer runtimes. Be it the Seoul P4 or the CREE XR-E, they both use the same CREE XR-E die, just implemented differently. You'll get a good amount more lumens out the front, or consume less power doing it, and even run cooler, than options that were not available six months ago.


Anyhow, more Seoul P4 parts showed up from yet another source today, so I better get to testing before the night is over.


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## ViReN (Jan 9, 2007)

From what I have been reading If i understand correctly for SP4 (summarizing)

1) The "Tint Shifting (whole LED turns Blue)" (is a function of Current) will occur only after you cross the limit (perhaps 400 mA) and that Tint shifting is also partly a function of heat. better the heat sinking, you have greater chance of reducing it at least partly.

2) where as "Tint Variation" (on parts die), is majority a function of LED Construction & resultant of poor die-bonding (explained in detail in above posts)

So Basically, as long as you are within current limits, have better heat sinking & that you have a LOP Reflector, you are fine.... the SP4 will "Out Throw" _any flux bin_ of luxeon _at any current level at any time_


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## thezman (Jan 9, 2007)

NewBie said:


> Anyhow, more Seoul P4 parts showed up from yet another source today, so I better get to testing before the night is over.


 
I hope there are no worms in this batch of apples.


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## NewBie (Jan 9, 2007)

Viren, it all depends it appears, on the batch, and in the Seoul P4 emitters I got from mouser, I get four shifters (each at different currents), and one really great one. One of the four had an issue with it, which is covered earlier. I got two Seoul P4 emitters from dat2zip that don't shift much, there is a video of them. I don't feel it would be fair to say they all do X, as it could be better or worse. Example, since they all do not, shift blue at 400mA, that would be an unfair statement. Some do it at 500mA, some at 700mA, some at 1000mA, and I've got one that hangs on pretty darn good, even at 1.5A.

McGizmo has a whole batch of flashlights that don't shift at all.

IMHO, it is pretty hard to lump or stereotype something that has variance.

For a relative size of things, I placed a dime on the old vice in front of the heatpiple based heatsink:







I almost forgot this graph which could be useful for some. I also took my least shifter (my very best Seoul P4), and ran a set of measurements on it.

The blue line is the shift over current, with slug held pretty darn close to ambient.
The pink line is with the current held to exactly 750mA, and the slug temperature 
moved from 25C to 95C. This should help to understand what happens to the shift with current and while a flashlight heats up.


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## Hellbore (Jan 9, 2007)

That's a nice heatsink, I have one on my dual-core Athlon 64 and it cools very well!


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## ViReN (Jan 9, 2007)

wow... NewBie.... The above graph explains the fact very clearly.

Heat management will be crucial for high current drive levels.

so to be on safe side... a best 'compromise' will be to use as good as possible heat sinking and stay between 300 - 500 mA ... with Orange Peel Reflector (to reduce individual 'on die' tint variation).. I know, the lumens would be less...which flashaholics would not like 

I remember one discussion in reference to New Generation LED's McGizmo forum, refering to reducing the drive levels, yet the light will be able to deliver more lumens & more runtime as compared with luxeon.


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## NewBie (Jan 10, 2007)

Well, got only a few emitters tested from these next batches I have. 3 to be exact.

The one I called Seoul P4-T Lot1 #1 pulled 50mA and made no light, had a lower Vf, and right around 53mA it started to make light, and the Vf read 2.3V, about 0.5V lower than typical, and it's output was lower than typical.

I figure the ESD diode in it is leaky, and no, I did zap it. In my experience, if it was the LED die, it would not have had a typical LED die curve, just offset.

The funky one is in light (bright) green squares.


Anyhow, updated charts:











.


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## Opto-King (Jan 10, 2007)

So, what you are "telling us" is that the T and U bin are almost the same when driven at 1-400mA and that you only "need" the U bin if you are going to drive the LEDs at a high mA?

Also, if I'm reading your chart correct it seems that the LEDs you have tested are above 118lm @ 350mA.

Nice work by the way!


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## EngrPaul (Jan 10, 2007)

At $2 for a U-bin over a T-bin, why would we CPF'ers ever want to use T-bins at all?


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## NewBie (Jan 10, 2007)

Opto-King said:


> So, what you are "telling us" is that the T and U bin are almost the same when driven at 1-400mA and that you only "need" the U bin if you are going to drive the LEDs at a high mA?
> 
> Also, if I'm reading your chart correct it seems that the LEDs you have tested are above 118lm @ 350mA.



Hell no! You be a dreamin' bigtime!

118lm @ 350mA would be a pipe dream on these. For that, you would need at least a V bin, maybe more once you account for die heating.

The chart is NOT in lumens or lux @ 1m. Just a relative comparision.


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## Doug S (Jan 10, 2007)

Jar, there sure is a bunch of great eye candy for us technical types in this thread. Thanks. BTW, there is a discrepancy [typo?] in your post #207 w.r.t your numbering of the funky emitter; #1 vs #2. 
I find the graph you posted in #204 to be interesting. At least with this sample the temperature plus current color shifting very closely parallels the BB planckian locus more so than I recall from data you published long ago for other power leds though possibly this may be just due to the different range of currents in the two datasets.


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## NewBie (Jan 10, 2007)

Could you elaborate on the typo? Are you talking ( ) or funky and Funky?

The tint shift direction does vary a little bit, depending from which bin you start off at. I wouldn't take this as a rule, the tint shift direction, but as a stereotype. I've ran some Philips LumiLEDs Luxeon III XO bins that follow or parallel the line closely also, but not every one of them shifts identically. The left and right are generally similar, with some variation of the parallelism from one LED to another, from what I have seen in the past. Other color bins have more departure from parallelism, but I have not ran a big enough sample. Sorry guys, I'm not going to run a bunch of these for color, it takes many hours to do...

Here is the XRE chart below, and I'll see what I can dig up on the Luxeon tonight, if I remember.


----------



## Doug S (Jan 10, 2007)

Doug S said:


> BTW, there is a discrepancy [typo?] in your post #207 w.r.t your numbering of the funky emitter; #1 vs #2.






NewBie said:


> Could you elaborate on the typo? Are you talking ( ) or funky and Funky?



Sure. Text describes #1 as the funky one but graph labels #2 as the funky one.


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## NewBie (Jan 11, 2007)

The funky one is in light (bright) green.
In the first graph (Vf) it is labeled as:
Seoul P4-T lot1 #2 (funky)
In the second graph Relative Brightness it is labeled as:
Seoul P4T Lot1 #2 Funky

That is the second real odd ball part I've found in 10 so far (leaky=funky), and also the two more 700mA tint shifters, but at higher current levels the one that started feeling blue around 500mA.

Am I still missing something?


----------



## NewBie (Jan 11, 2007)

Okay, finished up three more Seoul P4 emitters, nothing odd found (good thing!)

All the Seoul P4-T Lot1 parts are from the same Intensity, same color bin, and the same single Vf bin. One of the nice things about buying reels, they label exactly what is on the reel, on the reel.

The series I am starting on now, are all Seoul P4-U, and are from the same Intensity, same color bin, and the same single Vf bin. In fact, they are from the same Vf, and color bin as the Lot1 parts.

Anyhow, updated graphs:


----------



## [email protected] (Jan 12, 2007)

Hmm, looks like someone has been busy taking measurements...


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## limks (Jan 12, 2007)

Great review. Many thanks.


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## NewBie (Jan 12, 2007)

Okay, I've updated the Vf chart with the results of the rest of the Seoul P4-U bin. The Vf bin for lot1 and lot2 is 3.25V - 3.50V and Seoul P4 binning is done @ 350mA.







I've expanded the Vf plot a bit:







And the Relative Brightness chart:







One of these last four U bins was below the T bins. Otherwise, you can see a slight split up at 1000mA, between the T bins and U bins. Generally, the U bins have a higher Vf than the T bins.


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## easilyled (Jan 12, 2007)

NewBie said:


> FYI, I rinsed off the Seoul P4 again, it keeps reaching out and grabbing dust out of the air... : (
> 
> If I decide to use many of these, I might think about making my own mini laminar flow bench, along with a +/- ion generator for equalizing charges to help keep the static down. Besides rinsing with water or isopropyl alcohol/water mix, anyone come across any great ideas on removing/preventing the dust collection on the Seoul P4?




I had an idea for removing the dust but its only hypothetical since I haven't
actually had any of these leds to play with yet.

I was wondering whether making a loop of sellotape, sticky side out,
then *very lightly* applying the sticky side to the gummy dome to remove
dust would work. 

Please bear in mind that at this point I don't know how delicate the 
gummy dome is.


----------



## NewBie (Jan 12, 2007)

I have some more K2 parts and Luxeon III parts that I think I might run a couple of curves on tonight, just for additional comparision.

I would be interesting to blast it with one of those de-ionizing compressed air guns usually used for static neutralization, to see if it would reduce the miracle dust magnet personality.


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## MikeSalt (Jan 12, 2007)

I think I'll stick by Cree. Any flashlight that permits access to the LED module will allow dust to settle on the 'gummy bear' lens. Eventually, 240 lumens through a few microns of dust will not only reduce output, but will also make the module heat up under refelection, causing premature failure.


----------



## EngrPaul (Jan 12, 2007)

A little dust won't stop me. All you have to do is a final cleaning and air blast before assembly, including front glass, reflector, and emitter. I do that anyway.


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## MikeSalt (Jan 12, 2007)

My point is this. SureFire will have known about both the Cree XR-E AND the Seoul S4 due to their excellent research department. Being the premier manufacturer of flashlights, they will have considered and researched all factors including quality of beam, CRI, lack of tinting, durability etc... And after several $10,000s of consideration, they have stuck with Cree for a reason. With your reputation at stake, you pick the best, not necessarily the brightest.


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## hotbeam (Jan 12, 2007)

MikeSalt said:


> Eventually, 240 lumens through a few microns of dust will not only reduce output, but will also make the module heat up under refelection, causing premature failure.


I think that is way over dramatisation.


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## nightrider (Jan 12, 2007)

Great work Newbie. I've been following this thread from the start... lots of nice photos and discussions.

Any chance of getting an XR-E and a Luxeon III thrown in the Current vs Intensity chart?

Thanks.


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## McGizmo (Jan 12, 2007)

MikeSalt said:


> My point is this. SureFire will have known about both the Cree XR-E AND the Seoul S4 due to their excellent research department. Being the premier manufacturer of flashlights, they will have considered and researched all factors including quality of beam, CRI, lack of tinting, durability etc... And after several $10,000s of consideration, they have stuck with Cree for a reason. With your reputation at stake, you pick the best, not necessarily the brightest.


----------



## 3rd_shift (Jan 12, 2007)

MikeSalt said:


> My point is this. SureFire will have known about both the Cree XR-E AND the Seoul S4 due to their excellent research department. Being the premier manufacturer of flashlights, they will have considered and researched all factors including quality of beam, CRI, lack of tinting, durability etc... And after several $10,000s of consideration, they have stuck with Cree for a reason. With your reputation at stake, you pick the best, not necessarily the brightest.



Welcome to cpf. 
Interesting points.
Some of which I'm inclined to agree with already.
It would still be interesting to see if SSC comes up with a better material for the led dome.
As of right now, this led seems more at home inside a "sealed" flashlight, or lighting device.
It would not be a good choice (for example) in a C, or D Maglite mod where the head is easily removed, as dust would be a near instant issue for the led.

PS;
Have a look at some of McGizmo's work.


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## NewBie (Jan 12, 2007)

nightrider said:


> Great work Newbie. I've been following this thread from the start... lots of nice photos and discussions.
> 
> Any chance of getting an XR-E and a Luxeon III thrown in the Current vs Intensity chart?
> 
> Thanks.




Sure, I got home early tonight, so I'll hop on it right after I finish eating dinner.


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## yaesumofo (Jan 12, 2007)

Please explain your statements.

Do you have any proof that would support this statement?
Wouldn't the same be true of the cree emitter if some dust settled upon the glass lens of the XRE? If not why not?
Somehow I don't believe that dust (in small quantities) has any negative effect upon the durability of either of these emitters or any of the Luxeon emitters, for that matter. This is based upon the fact that I have never seen a failure of a emitter due to dust. I have plenty (100+) of LED based flashlights. Some even have tiny specs of dust right on the emitter. None have failed. In fact I would go out on a limb and say that the dusty emitter is more likely to fail because of botched attempts to clean them than the dust itself. I have several lights which run HOT (ARC LS) none have failed due to heat yet.

Yaesumofo



MikeSalt said:


> Any flashlight that permits access to the LED module will allow dust to settle on the 'gummy bear' lens. Eventually, 240 lumens through a few microns of dust will not only reduce output, but will also make the module heat up under refelection, causing premature failure.


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## yaesumofo (Jan 12, 2007)

I think this is the understatement of the centrury.
Yaesumofo



hotbeam said:


> I think that is way over dramatisation.


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## NewBie (Jan 13, 2007)

Yaesumofo,

The Seoul P4, and the way it actually pulls dust out of the air is really very uncanny. I've never seen anything like it. Whatever they did, they could make a product out of whatever they used and market it to housewives. 

But, you can clean it, and get it into a sealed light.


Anyhow, back to testing...and we have updated graphs...


I tested a number of Luxeons and tossed them on the graphs below:







Take note of where the Seoul P4 Vf fall in reference to the K and H bin Luxeons, above.













The light output comparision above is very interesting, especially when you compare the various bin Luxeons to the Seoul P4 which uses the CREE die.


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## ViReN (Jan 13, 2007)

> I've expanded the Vf plot a bit:
> 
> 
> 
> ...



NewBie, Thank for the great efforts. It is highly appreciated.

 EDIT: Since you have compared Vf of Luxeons and Crees... It seems logical for me to look for intensities at various currents of others as compared to Seoul SP4. After all intensities (is what matters to most ppl) should also be compared apart from the Vf's. without the Intensities of others compared, the SP4 intensities chart remains incomplete.

Would it be possible for you to include the Intensities of others like Cree's and luxeons as well when comparisons intensities?

EDIT: Doh... its already done  Thanks NewBie .... just one request still ... if possible it would be great if you could include Cree's P4 or P3 bin too for the brightness comparison with SP4


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## ViReN (Jan 13, 2007)

the above charts are so helpful... wow...

Imagine.. what brightness (100) TWOH can achieve with 900 mA can be achieved by roughly any of Seoul SP4 with 250 mA.. yes Vf @ 250 mA

Compared Vf at same Brightness may be near or around 3.3 V for both the cases.

So that means Seoul P4 is still more efficient by at least 900/250 = *3.6 Times !!!*

Time to get some Seoul P4's..... .... hmm.. who'z got them?.... let me visit sandwich Shopie


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## 3rd_shift (Jan 13, 2007)

Newbie,
just for giggles when you have time, can you toss in a Luxeon5, or two?
It looks like the SSC and Cree XRE leds could give even, a good Lux5 a run for it's money. :naughty:


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## NewBie (Jan 13, 2007)

Okay, I've made another graph to put things in perspective.

Current does not tell all about an LED.

To the converter and battery, what really counts is the power it consumes, which is known as Watts. Watts is the product (multiplication) of Voltage times Current.
W=V*C (aka P = V*I)

So, I've taken the Power consumed and plotted it against the light output on the vertical scale below:







There are enough datapoints there, that it is getting hard to make things out, so I've produced a larger version of the graph that you can use, download it here:
http://www.molalla.net/~leeper/sp4int3.png

On the larger graph, you will notice that there are some kinks in the lines, which were due to the resolution of the readings on the early parts. I tore apart the power supply and added dual 10 turn potentiometers on the current adjustment, which allows for much finer adjustments, so the later measurements are much smoother, as well as utilized different meters for better resolution. 

I have the Seoul P4-T that is still mounted to the heatsink, which allows me to verify the setup is correct, before the start of each set of measurements, it is my reference to ensure consistency.

Both lot1 T and lot2 U are all from the same Vf and tint bins. Lot1 T is specificed as 70-90 lumens, and lot2 U is specified as 90 to 110 lumens, both at 350mA.

I hope to get to the CREE tonight, if time permits. I should say CREE XR-E, since the Seoul P4 also uses the CREE die...


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## CM (Jan 13, 2007)

3rd_shift said:


> Newbie,
> just for giggles when you have time, can you toss in a Luxeon5, or two?
> It looks like the SSC and Cree XRE leds could give even, a good Lux5 a run for it's money. :naughty:



Please pardon me for chiming in to your question to Newbie. I've modified several KL6's with Crees. As far as giving the Lux V a good run for the money, it's comparable to a W bin Lux V when biased at 950mA. It's brighter than any of the stock KL6's which probably use a V bin. This equates to about 30% less power than a premium bin Lux V but having an output that is about the same. Throws a heck of a lot better too. I have no intentions of buying any more Luxeon based lights until Lumileds can up the ante.


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## ViReN (Jan 13, 2007)

> I have no intentions of buying any more Luxeon based lights until Lumileds can up the ante.



I wont buy either... even the ante Luxeons... Until NewBie Tests em 

Great Work NewBie, It's really helpful to many of us and saves a lot of $$$.

Your work is highly appreciated.

ViReN


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## NewBie (Jan 13, 2007)

Okay, well, I tested a second CREE, which is #2 on the overkill heatsink.

CREE #1 is already mounted on a 2" by 3" by 0.165" piece of copper sheetmetal only.

The device used for "brightness" testing was an Extech 407026 mounted to a white pail, such that the light from the LED would not have a direct path to the sensor. LED was inserted in a hole in the jug.

Meter here:
http://www.extech.com/instrument/products/400_450/407026.html


Caveats:
-Like all light meters, it is not a spectroradiometer, and will have some error depending on the spectral output of the LED. Expect any errors due to spectral differences between LEDs to cast doubt on accuracy of measurements.
-CREE #2 was not mounted on the overkill heatsink, and it's thermal solution is different than the rest of the LEDs under measurement.
-CREE LEDs were both directly soldered to copper, NOT a MCPCB.
-The CREE LEDs were both from the "low output" P3 bin (73.9 - 80.6lm), *NOT the Q3 bin (93.9-100.4 lm) which would be in the Seoul P4 U bin range (91.0-118.5 lm).*
-CREE #1's bin appears to be higher than what the vendor that supplied said it was. Possible mixup at the vendor.

For the testing to be fair, I'd need to obtain parts from the same lumen bins from Seoul and CREE. This comparision here is a bit biased, as I do not have any Q3 bins from CREE yet. Some folks have been running around saying the Seoul P4 is brighter than the CREE XR-E, which is dicey at best to say, since we are not comparing the same lumen bins. Of course a part from a higher lumen bin will be brighter!!! It may be that companies are paying premium for the top end CREE bins, like Surefire, and thus the lack of availability- *conjecture on my part*.


Anyhow, the new graphs:







The BIG version:
http://www.molalla.net/~leeper/sp4int3.png


.


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## Gryloc (Jan 14, 2007)

Newbie, 

I just want you to know that I really like the Seoul P4 LED! I ordered one from Mouser (just a T-bin) and it is just awesome. Comparing side by side to a TWOH LuxIII, the color is a bit more blue, but not too much. By it's slight sky blue tint, I would say it would be in the Luxeon YO range, close to the XO area. 

The brightness is just amazing!! I have a few new crees now, but I just realized just how hard it is to use in flashlights. Very few reflectors work with it, and the only optic I have, the Cree XR-E TIR optic, isn't at all impressive. 

I have the P4 here and it does work well with different reflectors, such as the D cell Maglite and the different IMS 20mm and 27mm reflectors. I decided to throw this P4 into my very first true flashlight mod that I created. I modified the Streamlight Tasklight 3AA Luxeon to handle a Fatman driver and a V-bin LuxV. This thing seemed bright back in the day, but over time, it dimmed, and the LuxIII was beginning to put it to shame. So, I decided to retire the poor, tired LuxV and give the thing an upgrade. 

The Fatman driver in this thing has a messed up trace somewhere, so the built on trimmer does not work right. The circuit wont sense any resistance so it will not limit the current. With a fresh set of batteries, the Fatman will try to dump as much current as it will allow into the LED. For the LuxV, it didn't phase it any because it had such a high Vf. With the P4, I measured 2.6A at the battery and 1.7A at the LED. Of course, I used the amp-meter function of my multimeter, so the current will be a little higher (will be ~1.10 times more normally). With these high currents, I notice that the tint shifts a bit more blue after being on for about 5 seconds. I dont leave this on for very long, but I would like to drain the NiMH's a little so it can be on longer. I may just have to fix the Fatman or replace it if I want to keep using this flashlight.

I seen some people asking to test how hight of a current the P4 and the XR-E can handle. My P4 handles <1.8A without fusing open, but keep it cool! I hear the gummy domes keep the die and phosphor cooler than the old plastic dome, so that explains why I feel the heat on the dome. This is just like the K2. I still need to play with the XR-E. I have three set up on a massive Al heatsink. We'll see...

...Well, what blows me away is the comparison between this light, using the IMS SO27XA, and my quad TWOH Maglite using IMS SO20XA reflectors. The brightness of the two beams look very similar! Seriously! The beam of the Tasklight is just slightly narrower with a larger corona. I really wish I can afford a luxmeter right now!

Here are some beam shots. My ceiling is spackled, but painted with glossy paint. 




Here is without any optics at all. This shows the floody light to compare overall brightness. I held both lights up to the glossy painted wall at about 0.5 meters away. 
NOTE: try to ignore the reflected light, unless you want to use that as a comparison.



Wow! Sorry my camera cannot be manually set, so everything was in auto.

As proof, here is the setup, even if it is a little fuzzy.



By the way, the poor SO27XA reflector had to be trimmed a bit to fit into the head, so over time, a bit of the reflector material was flaking off. I also tried to clean it once . Additionally, the lens (all I could find at the time) is about 3mm thick and has a chip in one edge. I bet that all this might be hurting the light output a bit.  Now I need to get a new Fatman, a new reflector, a new lens, U-bin SSC P4, and Tasklight Luxeon to re-do this thing. It needs to be re-done. Then it will be truely awesome!

Sorry if it sounds like I am changing the topic of things, but I thought I would share my findings. I wish I could have the equipment to test the LED better like you, Newbie. I like all the results that you have come up. The measurements you have come up with are amazing! You work so hard for all of us at CPF and it is just great! Like others have said, keep up the good work.


-Tony


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## NewBie (Jan 14, 2007)

I fully understand having to grind down the reflector for the Seoul P4, and also having to shim it up ~0.30" to fit into existing solutions. Non-perfect reflectors sure help with a variety of things, and also the rough surface or jeweled ones.

Here is what I got out of a "perfect" MagLite D cell reflector with the Seoul P4:







There are a number of different pictures of the Seoul P4 and various reflectors earlier in the thread, along with some videos of the tint shifting.

I had five of the 13 I tested for this that had various issues. 3 of them would shift extremely blue at 1 Amp. One definitely had a die delamination problem. And I had the leaky one, that drew 50mA and made no light (normally they make light under 1 mA). Above that, it made light, and for the most part, acted like any other Seoul P4, just hampered a bit. Oh, and there was the U bin that put out less light than a T bin.

It is a different beast than the Luxeon III, really smoking the current LumiLEDs parts for sheer light output. It isn't a perfect part, so the white wall warriors will want to keep in mind, do you want lots of light, or a virgin white wall beamshot...

I'm very glad to hear you really like your Seoul P4!

It is a new part, and I imagine it will continue to evolve and improve as they dial things in.


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## yaesumofo (Jan 14, 2007)

Newbie, I wonder if the Seoul has some sort of charge on it.
If it is positively charged (static) and the the dust has a negative charge on it (or the other way around) maybe one needs to work in a static free with non charged air (filtered)flow around the part maybe that would solve the problem.
Maybe just applying some sort of anti static charge to it would work.

Remember in the days of Lp's they used to sell a sort of static shooter which you would aim at an LP and the dust would literally fall off the album. maybe this needs to be applied ti the packaging and or the emitter.
Just thinking out loud here I know nothing about the topic really just guessing. 

Yaesumofo



NewBie said:


> Yaesumofo,
> 
> The Seoul P4, and the way it actually pulls dust out of the air is really very uncanny. I've never seen anything like it. Whatever they did, they could make a product out of whatever they used and market it to housewives.
> 
> But, you can clean it, and get it into a sealed light.


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## NewBie (Jan 14, 2007)

yaesumofo said:


> Newbie, I wonder if the Seoul has some sort of charge on it.
> If it is positively charged (static) and the the dust has a negative charge on it (or the other way around) maybe one needs to work in a static free with non charged air (filtered)flow around the part maybe that would solve the problem.
> Maybe just applying some sort of anti static charge to it would work.
> 
> ...




Yes, I mentioned that earlier in the thread...

Haven't had a chance to try it myself, yet though. The silicone Seoul uses is so sticky though, that once on there, you may need a blast of air to get it back off. They make anti-stat compressed air nozzles.

Last night, when taking the Seoul P4 off the reel strip, I noticed that they even had dust on them already from the factory. Nothing a good cleaning can't fix, and keeping it in a home made forced airflow bench wouldn't take care of though.


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## Julian Holtz (Jan 14, 2007)

Hi!

Thanks for all this work, NewBie!

I have one question about this chart:
http://www.molalla.net/~leeper/sp4int3.png

Does it mean that the Cree XR-E have roughly the same brightness als the Seoul P4s when opperated at the same watt number?
To me, it seems like this.

I like the form factor of the Crees much better, so I would rather like to use them instead of the Seoul...

Thanks in advance,

Julez


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## NewBie (Jan 14, 2007)

It looks like they are pretty close, however, I have the P3 binned XR-E, which is a lower binned part than the Seoul P4-U, and the Seoul P4-T is a pretty wide bin (70-91 lm) and the Seoul P4-U is also quite wide (91.0-118.5 lm).

As you can see, there really isn't that much difference between the Seoul P4-T and Seoul P4-U, on the measured parts. Going from the top end to the bottom end of the Seoul T and U bins, you'd see a 40% difference. As it stands, with parts from the same tint and same Vf bin, there is only a 18% difference between the highest output and lowest output ones, and both of those happen to be U binned parts?!?! Seoul P4-U lot2 #2 is the highest output and Seoul P4-U lot2 #4 is the lowest output of all the parts. All the T binned Seoul P4 fell between those two, as well as the Seoul P4-U #1 and #2 from dat2zip fell between those two U binned parts.

I forgot to mention to Gryloc...
-one has to make sure they electrically isolate the slug of the Seoul P4 in most flashlights. This is very important, since most flashlights are minus body, and the Seoul P4 is a + slug. This is beyond the reflector grinding and emitter shimming I mentioned.

As I mentioned earlier, using a light meter instead of a spectroradiometer or other tool that can measure the output at each point in the color spectrum, may introduce errors that are not accounted for. The Seoul P4 and the Luxeons in that chart have a better thermal solution for those measurements, since I'd made the setup for the P4 type packaging.


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## Gryloc (Jan 14, 2007)

Newbie, yeah, I remembered long ago in this thread how the slug was positive. I sacrificed an old Luxeon I star for this. I heard somewhere that the Luxeon star (1/3/5) base has better thermal conductivity than the [generic?] Cree stars floating around the net. I also didnt want to foul up the only Cree XR-E star I had with solder yet. I am unsure if I want to solder an XR-E on it yet.

Also, that reflector was trimmed down years ago, so I was lucky it was nicely focused for the P4. Because I trimmed it years ago using a dremel, it is looking pretty trashy today. Oh well...

Well, I was suprised that I didnt get a crazy reaction for finding that my *one* mildly overdriven SSC P4 was comparable to 4 T-binned LuxIIIs (around 320lm I would assume). I know that is lumen output, and you can see with that floody beamshot I made earlier, the Maglite was only slightly brighter. I am saying that I am amazed that I can get similar flux output with one SSC P4 and the 27mm reflector as 320lm with 20mm reflectors. Am I missing something? Is this just normal and I am easily amused?   


-Tony


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## Gryloc (Jan 14, 2007)

Crap. Error with CPF and I double posted. Sorry...


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## NewBie (Jan 14, 2007)

Gryloc said:


> Newbie, yeah, I remembered long ago in this thread how the slug was positive. I sacrificed an old Luxeon I star for this. I heard somewhere that the Luxeon star (1/3/5) base has better thermal conductivity than the [generic?] Cree stars floating around the net. I also didnt want to foul up the only Cree XR-E star I had with solder yet. I am unsure if I want to solder an XR-E on it yet.
> 
> Also, that reflector was trimmed down years ago, so I was lucky it was nicely focused for the P4. Because I trimmed it years ago using a dremel, it is looking pretty trashy today. Oh well...
> 
> ...



Those stars are not made by CREE, but by secondary companies that mount the CREEs on MCPCB, such as the ones ETGTech had done for them.

Three Luxeon T @ 1A should roughly equal a Seoul P4 @ 1A, or two Luxeon III U bins @ 1A- when heatsinked very well.

When we get to comparing stuff with different tint colors, it is hard to make a decent evaluation, and a single shot isn't usually sufficient to see the differences, one really need a set of bracketed shots (different exposure levels), since digital cameras have such a narrow latitude or dynamic range, as compared to the human eye.

1700mA, imho, isn't mildly overdriven...lol!

1000mA is their Absolute Maximum Rating, and 350mA is their specification level for Electro-Optical characteristics on the current datasheet.

Their web page is here:
http://www.seoulsemiconductor.com/_homepage/home_eng/product/product.asp?topCODE=1&midCODE=25

Datasheet is here:
http://www.seoulsemicon.co.kr/_homepage/home_kor/product/spec/W42180.pdf


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## NewBie (Jan 14, 2007)

Gryloc said:


> Newbie, yeah, I remembered long ago in this thread how the slug was positive. I sacrificed an old Luxeon I star for this. I heard somewhere that the Luxeon star (1/3/5) base has better thermal conductivity than the [generic?] Cree stars floating around the net. I also didnt want to foul up the only Cree XR-E star I had with solder yet. I am unsure if I want to solder an XR-E on it yet.
> 
> Also, that reflector was trimmed down years ago, so I was lucky it was nicely focused for the P4. Because I trimmed it years ago using a dremel, it is looking pretty trashy today. Oh well...
> 
> ...




The star is not made by CREE, it is done by distributors, such as ETGTech, who send the parts out to companies to have them mounted on MCPCBs.

Three Luxeon III T bins should equal a Seoul P4. Or two U bin Luxeon III.

On of the problems with comparing emitters, is when folks compare different tints. To be fair, one would need to get the same tints. Also, a single shot is usually not a good way to do comparisions, as cameras lack the latitude or dynamic range of the human eye. However, one can always do a set of bracketed shots, where you do five different shots, at different exposure levels.

IMHO, I wouldn't call 1700mA mildly over driven...lol! That is 170% of the Absolute Maximum Rating!

Seoul lists 1000mA as the Absolute Maximum Rating on their current datasheet, with 350mA being the level for Electro-Optical characteristics @ 25C.

The datasheet is found here:
http://www.seoulsemicon.co.kr/_homepage/home_kor/product/spec/W42180.pdf

The web page for the part is found here:
http://www.seoulsemiconductor.com/_homepage/home_eng/product/product.asp?topCODE=1&midCODE=25

There is no best LED, but there are a range of options, each of which has advantages or disadvantages. In some cases, a Luxeon is best, in others a Seoul or Nichia, or even an OSRAM or a CREE. It all depends on what you really need.

Seoul has nice projected reliability and life time graphs, one really nice thing about it, is later in the presentation, they show the effects of what a junction temperature of 90C does to the lifetime of their parts:
http://www.essc.co.kr/_HOMEPAGE/home_kor/product/spec/Reliability.pdf

Their color binning charts can be found in this older binning datasheet, on page 9:
http://www.essc.co.kr/_HOMEPAGE/home_kor/product/spec/BL25.pdf

Optics and such designed for the Seoul P4 can be found here:
http://seoulsemicon.co.kr/_HOMEPAGE/home_kor/product/product_Power_SP.asp?topCODE=2&midCODE=4

I've yet to find a volume source for reflectors designed for the Seoul P4, since it is different than the LumiLEDs Luxeons. But you can grind the reflector down, shim the emitter up 0.030", and insulate the slug to electrically isolate it, to use in older solutions.


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## McGizmo (Jan 14, 2007)

MikeSalt said:


> My point is this. SureFire will have known about both the Cree XR-E AND the Seoul S4 due to their excellent research department. Being the premier manufacturer of flashlights, they will have considered and researched all factors including quality of beam, CRI, lack of tinting, durability etc... And after several $10,000s of consideration, they have stuck with Cree for a reason. With your reputation at stake, you pick the best, not necessarily the brightest.



The use of the Seoul P4 in the limited edition SF Titan coupled with some comments reportedly made by some SF folks at SHOT seem to be in a bit of dischord with the comment above. 

SureFire is in a position with their command of both TIR optics and reflectors to exploit and take advantage of any number of LED's and their specific attributes. For such a large and conservative company, it is refreshing to see them quick on their feet and in sync with this volatile and everchanging technology.


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## NewBie (Jan 14, 2007)

I'd have to agree, it is nice to see Surefire now becomming nimble, especially when with the KROMA designed by SAIF for optics and such.

It is interesting to see them use CREE's XR-E in some lights, and the Seoul P4 in the one Titan limited edition.

It will be interesting to see what the future holds, it is refreshing to see small companies like Surefire still adapting to technology and market, as they grow.

Edit:

Engineering samples have been out for *many* months now, so in reality, folks have nearly been fiddling with them for a year now...not as nimble as I'd first thought in retrospect.


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## :)> (Jan 14, 2007)

I got the notion from PK's comments last night, that the introduction of the Seoul really threw them for a loop. It is my opinion, based upon PK's comments last night that because of the introduction of the Seoul P4, that Surefire was completely rethinking how they were going to proceed. PK indicated that they already had the dies created for the Cree optics WHEN Seoul sprung the P4 on them. 

-Goatee


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## Gryloc (Jan 14, 2007)

Yeah, I understand that you cannot directly compare warm and cool tints very easily with one picture. I wish could use the camera at home. I also understand that 1700mA isn't mildly overdriving. Its insane! I am very surprised, and lucky, that the LED didn't shift more than is has. I am lucky, too, that it didn't shift blue permanently.  I rechecked, and right now, I estimate that the current dropped to about 1500mA since the batteries had some intermittent use at such high currents and they had a chance to sit over night after being charged. The tint doesn't seem to shift at this current (I have observed by eye), so this may be an ideal current for just my LED. Besides, I always liked pushing the limits a bit with LEDs. Maybe the specs are just for the safety, but in fact, the P4 can handle current like the K2. The Cree XR-E seems to do fine at higher currents than its ratings. I understand that there isn't any long term tests to confirm this, though.

I shouldn't be doing too much damage to it like this, am I? The die can handle the current, but not the package (the bond wires). I don't know about what damage I may be doing to the phosphors if I let it get that hot, though. I should be alright, right? I will use this light only in short bursts until I find a better and safer use for the P4.

I seen you had the same problems with posting as I did. :thumbsdow 

Thanks...


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## McGizmo (Jan 14, 2007)

The XR-E has been out for some time now (not a year though?) but the P4 is a youngster. The first sample of Seoul's use of the EZ1000 I saw was a completely different package and unsuitable for collimation. No matter. I think some manufacturers probably got a wake up call from what has been seen at SHOT whereas others may be already awake and working but not ready for show and tell yet. I would not be surprised to see new lights show up this year which were *not* introduced at SHOT.


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## NewBie (Jan 14, 2007)

Be careful with any overdrive, as the Seoul P4 LED die is just epoxied to the slug, it is not soldered like other power LEDs. Make sure you heatsink them well, they need it, and it will help the epoxy to hold up over time.

Even on my monster heatsink, with some serious overkill heatsinking, running @ 1A, in a cold ambient, I am already seeing some light output drop. This test will take a lot of time to do.


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## nightrider (Jan 16, 2007)

NewBie said:


> -The CREE LEDs were both from the "low output" P3 bin (73.9 - 80.6lm), *NOT the Q3 bin (93.9-100.4 lm) which would be in the Seoul P4 U bin range (91.0-118.5 lm).*
> -CREE #1's bin appears to be higher than what the vendor that supplied said it was. Possible mixup at the vendor.
> 
> The BIG version:
> ...


Newbie. Thanks for adding the Crees and Lux IIIs to the Intensity graph.

It's definitely a let down to see that the U-binned SSC P4s are about the same intensity as the Cree XR-E (P3 bin). _"Possible mixup at the vendor?" Hmmm.

_Wow. Given that the top end of the XR-E's P3 bin is about 10 lumens less than the bottom end of the SSC P4's U-bin, I would have expected all of the Seoul P4 U-bin to be above the Crees on your intensity chart. So something fishy is going on.

I remember when I first heard about the Cree XR-E and all its _hyped _output figures... well, some of us were pleasantly surprised to find out the figures were true! The things really were much brighter than Luxeons! Now with the SSC P4's claim about upping the ante a good bit more, it looks like it really could just be hype in this case. Supposedly I could run a bottom of the U-bin SSC P4 and get 91.0 lumens @ 350mA, or about 200 lumens @ 1A (calculated using SSC's Relative Luminous Flux versus Forward Current chart). So I'm already to build a Triple Seoul P4 bike light and get at least 600 lumens out of it! (watch out HIDs!) But then your chart only shows the SSC P4 as being about the same as the P3-binned Crees (which in a triple config only gives me a little under 400 lumens). So in effect, I'm coming up about 200 lumen short of expectations with a triple SSC P4 LED configuration. Ok. HIDs still rule in the bike light world... for now. 

Anyway, I still have some U-binned SSC P4s on order and will report how they work out in a triple config.

Thanks again Newbie for all the detailed information that you have provided!


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## bombelman (Jan 16, 2007)

nightrider said:


> Supposedly I could run a bottom of the U-bin SSC P4 and get 91.0 lumens @ 350mA, or about 200 lumens @ 1A (calculated using SSC's Relative Luminous Flux versus Forward Current chart).



Me like !


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## ViReN (Jan 16, 2007)

ddoouubbllee ppoosstt

Lots of database errors occuring today ...


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## ViReN (Jan 16, 2007)

>



SSC P4 .... U Bin / T Bin ??? was that a Mix up?


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## Doug S (Jan 16, 2007)

ViReN said:


> SSC P4 .... U Bin / T Bin ??? was that a Mix up?



Not necessarily. Remember that these are binned on a lm/amp basis, not a lm/watt basis.


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## NewBie (Jan 17, 2007)

No, it was not a mistake ViReN.

One of the U bin devices is the lowest output of all the Seoul P4 I have, but is still better than the best Luxeon III U bin I tested:








At 1 Amp on the graph, it also ends up being the lowest output, but nudges a tad better than a defective T Bin with 50mA leakage current below that:






For a chart that has things marked clearer click on this link to get it:
http://www.molalla.net/~leeper/sp4int2.png


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## NewBie (Jan 17, 2007)

No, it was not a mistake ViReN. I actually peeled this part out of a sealed strip off a reel from Seoul.

One of the U bin devices is the lowest output of all the Seoul P4 I have, but is still better than the best Luxeon III U bin I tested:









At 1 Amp on the graph, it also ends up being the lowest output, but nudges a tad better than a defective T Bin with 50mA leakage current below that:






For a chart that has things marked clearer click on this link to get it:
http://www.molalla.net/~leeper/sp4int2.png


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## ViReN (Jan 17, 2007)

in either case, both T & U Bins of SSC P4 are same as P3 Cree XR-E in terms of lumens at a given current.... arent U bin SSC P4 supposed to be 91 lm @ 350 mA and T Bin SSC P4 lower than 91 lumens?

performance wise, Cree XR-E is performing better (must be because their solid construction and techniques used) as compared SSC P4's .... nevertheless the SSC P4's Rock... gonna get some from https://www.candlepowerforums.com/threads/148921 for first hand SSC P4 experience  ... and gonna try to open my L0P and mod it with SSC P4.... I am sure it is going to have lesser heat generation and 3 times output.... ... isnt that amazing....


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## NewBie (Jan 17, 2007)

Personally, I would not call them the same without having a real integrating sphere and a spectrally corrected (like a spectroradiometer) setup, instead of a lightmeter.

Depending on how you heatsink things in the end application, you could see different results.

Also, since the output is radiating differently, you may get higher peak lux with a Seoul P4, in an identical reflector, but have considerably less light in the flood area.

Either are a vast improvement over the Luxeons for their light output. Those that care about artifacts, should probably stay with the Luxeons or carefully evaluate the trade-offs, application, and personal preferences.

Don't forget, for retrofit in most applications, you'll need to shim up 0.30", grind the reflector, and ISOLATE the slug for negative bodied flashlights (most of them). Also suggested is a rough or jeweled reflector surface.


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## EngrPaul (Jan 20, 2007)

Newbie,

I have put U-Bin Seoul's in more than a dozen different applications this past week. The only one I had a problem with was the "10W-K2" GLIMT from what was Fifth Unit.

On high, the heat built up more quickly than the flashlight was designed to dissipate it. The emitter shifted blue, just like the testing you were seeing.

So I put the K2 back in this application and improved the thermal transfer a little better than stock.

Otherwise, all the color has been as good as or better than Cree once mixed by a reflector.

*EDIT: This GLIMT is pulling about 14W from the batteries! So it's probably pushing at least 2500 mA to the emitter. No wonder it shifted tint so fast. I have several applications pushing 1500 mA with no tint shift at all.*


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## ViReN (Jan 20, 2007)

> Don't forget, for retrofit in most applications, you'll need to shim up 0.30", grind the reflector, and ISOLATE the slug for negative bodied flashlights (most of them). Also suggested is a rough or jeweled reflector surface.



Noted


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## roguesw (Jan 21, 2007)

NewBie
you mentioned having to isolate the SSC emitter from -ve polarity flashlight body, would Arctic Alumina epoxy be enough by itself 
or should i put some kapton on the body of the light and then epoxy the emitter to the kapton?
thanks in advance for any advice
best regards
Des


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## zifnab69 (Jan 23, 2007)

hello, 
is there any flashlight with the seoul P4 led yet ?
thank you


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## wojtek_pl (Jan 23, 2007)

roguesw said:


> NewBie
> you mentioned having to isolate the SSC emitter from -ve polarity flashlight body, would Arctic Alumina epoxy be enough by itself
> or should i put some kapton on the body of the light and then epoxy the emitter to the kapton?
> thanks in advance for any advice
> ...


AA Epoxy is OK. If you want to be sure, just put some of Arctic Alumina on the emitter and let it dry. Then glue LED to heatsink. Of course do not forget to check conductivity between "+" and the heatsink.


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## roguesw (Jan 23, 2007)

wojtek_pl said:


> AA Epoxy is OK. If you want to be sure, just put some of Arctic Alumina on the emitter and let it dry. Then glue LED to heatsink. Of course do not forget to check conductivity between "+" and the heatsink.




Thanks Wojtek
one last question, how do i check conductivity between + and the heatsink
so i set my multimeter to ohm setting and just touch one probe to + anode on emitter and the other probe to heatsink?
if it has no value (infinity) then there is no conductivity right? if it has a value of 0, then the circuit can conduct?
thanks again
its been 13 years since i last touched a multimeter (high school science) and at the moment, the emitters and multimeters have not been bought yet
thanks again for your help
best regards
Des


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## wojtek_pl (Jan 24, 2007)

Sorry for another stupid question... Is SSC P4 brighter than Luxeon V ? I have [email protected] modified with Luxeon V and I wonder about upgrading it to SSC P4... Do it or skip it ?  :candle:

@roguesw 
Yes, You are correct.


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## StefanFS (Jan 24, 2007)

Wojtek,

Not necessarily very much brighter to your naked eyes. The big advantage would probably be longer runtime since the SSC P4 is more energy efficient than the Lux V. It also depends on the driver circuit.
Stefan


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## wojtek_pl (Jan 24, 2007)

My Luxeon V is powered by Fatman driver, set to 700mAh. Will SSC P4 be brighter than Lux V at 700mAh ?


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## StefanFS (Jan 24, 2007)

Dobry wieczór Wojtek,

Yes it should definitely gain in brightness. Problem is your eyes can't really discern it unless it is a gain about maybe 2-4 times in brightness (depending on the quality of your eyes. (LOL)). My mods at that approx. drive level have increased in brightness about 2-2.5 times. See EngrPauls excellent mods on Civictor and Fenix LT1, there are some really nice beamshots if I remember correctly. In the led section?.
Stefan


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## yaesumofo (Jan 24, 2007)

Here are a couple which have been made. 

McGizmo PD-S
PD-S mizer
27LT-S
27LT-S Mizer
I don't beleive there are any of the PD-S lights available. Maybe more in the future.
There may be more 27LT-S lights available. 

In practical use the PD-S in mizer (390mA) mode is a great little light.
The 27LT-S run at 917mA is a blaster mode light if there ever was one.


Yaesumofo

BTW welcome to the cpf. 


zifnab69 said:


> hello,
> is there any flashlight with the seoul P4 led yet ?
> thank you


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## McGizmo (Jan 24, 2007)

Yaesumofo,
Slight correction: The Mizer is ~ 290 - 300 mA.


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## Kiessling (Jan 24, 2007)

Why do you all think the SSC P4 (or the Cree for that matter) sport a higher luminous flux than a LuxV? Depending on bin, of course, they don't. They are mroe efficient and will sport about double the runtime than a standard LuxV ... at roughly the same brightness ... but with a different beam pattern.
bk

EDIT: scenario with both driven at 700mA


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## wojtek_pl (Jan 25, 2007)

So in other words SSC P4 will need less power to give the same brightness as LuxV ? 

I think I'll skip this change and I'll put my soon-to-be-delivered SSC P4 to my Smartfire flashlight...


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## Kiessling (Jan 25, 2007)

> So in other words SSC P4 will need less power to give the same brightness as LuxV ?



Very roughly speaking, yes.


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## NewBie (Jan 28, 2007)

roguesw said:


> Thanks Wojtek
> one last question, how do i check conductivity between + and the heatsink
> so i set my multimeter to ohm setting and just touch one probe to + anode on emitter and the other probe to heatsink?
> if it has no value (infinity) then there is no conductivity right? if it has a value of 0, then the circuit can conduct?
> ...



You may measure 1,000 ohms to 2,000,000 ohms, if you have the converter hooked up. A slug short to the flashlight body would measure a few ohms from the ve+ to the flashlight body. You can also not hook up the converter, and make your measurement then. Then you would read infinity.

Yes, 0 ohms means it is connected. If you plan on using Arctic Alumina epoxy, you can use a razor blade or even a sheet of plastic, to form a nearly see thru layer on the part, let it get somewhat hard, then attach it to the heatsink with the AA, which will form a decent insulator. Even Arctic Alumina has a pretty high thermal resistance, so keep the pre-bond, and bond layer as thin as possible.

I've had, and others have mentioned that during an impact, sometimes AA will pop loose from emitters, heatsinks, and even stars. I'd advise you to clean both surfaces with a solvent before bonding, and do not touch it. You might consider ever so slightly roughing up both surfaces with 600 or 800 grit sand paper, which seems to aid the bond strength.


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## roguesw (Jan 28, 2007)

NewBie said:


> You may measure 1,000 ohms to 2,000,000 ohms, if you have the converter hooked up. A slug short to the flashlight body would measure a few ohms from the ve+ to the flashlight body. You can also not hook up the converter, and make your measurement then. Then you would read infinity.
> 
> Yes, 0 ohms means it is connected. If you plan on using Arctic Alumina epoxy, you can use a razor blade or even a sheet of plastic, to form a nearly see thru layer on the part, let it get somewhat hard, then attach it to the heatsink with the AA, which will form a decent insulator. Even Arctic Alumina has a pretty high thermal resistance, so keep the pre-bond, and bond layer as thin as possible.
> 
> I've had, and others have mentioned that during an impact, sometimes AA will pop loose from emitters, heatsinks, and even stars. I'd advise you to clean both surfaces with a solvent before bonding, and do not touch it. You might consider ever so slightly roughing up both surfaces with 600 or 800 grit sand paper, which seems to aid the bond strength.





Thanks so much newbie !!!!
Keep up the good work.

best regards
Des


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## yaesumofo (Jan 28, 2007)

Wow!
Thanks
Yaesumofo



McGizmo said:


> Yaesumofo,
> Slight correction: The Mizer is ~ 290 - 300 mA.


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## Gryloc (Jan 28, 2007)

I second what Newbie says about the AA thermal epoxy. I used it to mount several LEDs on a heatsink and you do have to be careful to not allow the epoxy to get too thin. I had some LEDs not get fully isolated once. Also, I just discovered in my year old quad LuxIII maglite that three of the four LED emitters broke loose! Luckily, the the four SO20XA reflectors pressed the LED slugs in place in the special indents in Modamag's special maglite heatsink. Until I re-epoxy it, I will just use some thermal paste. I was blown away that they just broke loose! Oh well. Good luck!

-Tony


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## IsaacHayes (Jan 28, 2007)

Gryloc, it is possible that they broke loose when you were screwing on the lens bezel, and thus pressure was placed on the LEDs from the reflectors shifting as they twisted from the lens turning. I haven't had a problem with AA coming off, but I always clean both surfaces to make them free of oil, and press down firm to get a metal-to-metal interface, so a lot of AA oozes out. Even so, mine have not come off. The little that oozes out too, will adhere to the case of the led too.

Of course with the P4, you don't want the ideal thermal interface of metal to metal, as that would be a short. Ideally for the best thermal interface where a heatsink is tied to negative, you'd use an anodized heatsink.


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## NewBie (Jan 29, 2007)

Issac,

I've seen the Luxeons and Luxeon Stars that were AA'd, pop loose when the lights fell and hit basalt or andesite. In each case, I noticed a slight tint shift and less output when I utiized them later. I've also seen AA come loose from peltier modules, where I could not explain the drop in performance, and got to looking, and the big two inch by two inch peltier was loose and came away clean as a whistle on both sides. Two weeks ago, I needed to remove a ETGTech made star from some copper, I just gave it a sharp (sharp being key) but light rap, and the AA simply popped loose from the roughened copper surface, that I know in fact was oil free when it was bonded. So, I knew it worked well for removing stars from aluminum, but the copper I even roughed up considerably and it still popped loose.

Still, proper prep, and through mixing of the AA is important. The white ceramic AA will not ensure electrical isolation in and of itself.

If you ever need to remove AA, a little bit of heat and a pick is another method that can be used to unpot things, but practice first on something you don't care much about.


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## chris_m (Jan 30, 2007)

Regarding the dust on the gummy issue, I have to say that in my opinion this has been blown out of all proportion. I suspect most people using these LEDs wouldn't even have noticed had Newbie not brought it up. Having left one of my newly arrived P4s sitting on the desk for a few hours I still need a magnifier to see any dust at all, and even then it's pretty negligible. I think this has to be one of the most over-hyped "problems" ever!


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## EngrPaul (Jan 30, 2007)

chris_m said:


> Regarding the dust on the gummy issue, I have to say that in my opinion this has been blown out of all proportion. I suspect most people using these LEDs wouldn't even have noticed had Newbie not brought it up. Having left one of my newly arrived P4s sitting on the desk for a few hours I still need a magnifier to see any dust at all, and even then it's pretty negligible. I think this has to be one of the most over-hyped "problems" ever!


 
Dust+debris comes right off with a Q-tip moist with IPA. It's a non-issue unless your emitter is exposed to the atmosphere during usage (i.e. a Mag you use in candle mode)


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## cmacclel (Jan 30, 2007)

I have never seen AA Expoxy give way. I guess it's all in the prepatation. I always rough both surfaces and cleen them with Isopropanol Alchohol before assembly.

In fact I made a mistake once and needed to remove 2 stars and it was a nighmare 

Newbie whats your take on the best way to isolate the Seoul slugs? How much of a hit in thermal performance would be lost if you used some of the 2mill kapton tape?

Mac


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## cmacclel (Jan 30, 2007)

wojtek_pl said:


> My Luxeon V is powered by Fatman driver, set to 700mAh. Will SSC P4 be brighter than Lux V at 700mAh ?




The P4 light will throw at over 2x of the Lux V. In a Mag Smooth reflector my prototype Seoul P4 measures over 20k lux at 1 meter. A nice Lux V measures under 10k lux.


Mac


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## easilyled (Jan 30, 2007)

EngrPaul said:


> Dust+debris comes right off with a Q-tip moist with IPA. It's a non-issue unless your emitter is exposed to the atmosphere during usage (i.e. a Mag you use in candle mode)



Could you post a link where I can buy these Q-tips/IPA please?


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## wquiles (Jan 30, 2007)

cmacclel said:


> The P4 light will throw at over 2x of the Lux V.


That is my experience as well with the Turbo LED modules I used with my SF M6 (using the KT4 reflector). Plus, the Seoul was using significantly less power 

Will


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## curtis22 (Jan 30, 2007)

easilyled said:


> Could you post a link where I can buy these Q-tips/IPA please?



A Q-tip is a cotton swab on a stick commonly used for things like cleaning ears. I'm guessing IPA is isopropyl alcohol.

There are way too many TLAs in this thread.


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## EngrPaul (Jan 30, 2007)

easilyled said:


> Could you post a link where I can buy these Q-tips/IPA please?


 
www.walmart.com

Hint: IPA = Isopropyl "Rubbing" Alcohol, Q-tips = cotton swabs.


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## NewBie (Jan 30, 2007)

cmacclel said:


> I have never seen AA Expoxy give way. I guess it's all in the prepatation. I always rough both surfaces and cleen them with Isopropanol Alchohol before assembly.
> 
> In fact I made a mistake once and needed to remove 2 stars and it was a nighmare
> 
> ...




Annodize is probably one of of the better methods to isolate. One could also solder to a copper heat spreader, to increase the transfer area, then use a thermal epoxy. With the Anodize, you can make the high thermal resistance Arctic Alumina thermal epoxy as thin as possible. The stuff that is on the Surefire flashlights reminds me a lot of the flexible thermal epoxy that is sold by Masterbond. Flexible materials typically have better shock resistance. Their thermal products are found here:
http://www.masterbond.com/sg/masterbond_tcsg.pdf

There are also thermal epoxies that have spacer balls in them, if the surfaces are smooth and flat, 2-3 mils should be plenty big enough.

There is also the reality of as good as possible, vs. reality and it's effect on performance.


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## wojtek_pl (Jan 30, 2007)

wquiles said:


> That is my experience as well with the Turbo LED modules I used with my SF M6 (using the KT4 reflector). Plus, the Seoul was using significantly less power
> 
> Will


Hmmmm.... You say it's upgrade time ? I have a spare SSC P4 in a drawer...


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## Curious_character (Jan 30, 2007)

NewBie said:


> Annodize is probably one of of the better methods to isolate. One could also solder to a copper heat spreader, to increase the transfer area, then use a thermal epoxy. With the Anodize, you can make the high thermal resistance Arctic Alumina thermal epoxy as thin as possible. The stuff that is on the Surefire flashlights reminds me a lot of the flexible thermal epoxy that is sold by Masterbond. Flexible materials typically have better shock resistance. Their thermal products are found here:
> http://www.masterbond.com/sg/masterbond_tcsg.pdf
> 
> There are also thermal epoxies that have spacer balls in them, if the surfaces are smooth and flat, 2-3 mils should be plenty big enough.
> ...


I've been following EngrPaul's method of modding the P4 into Luxeon lights (using Arctic Silver epoxy for insulation), except I use Arctic Silver compound between the copper slug and flashlight instead of Arctic Silver epoxy. I did some calculations and was surprised at just how sloppy I could be and get away with it. Using the measured diameter of the P4 base and published values of Arctic Silver thermal conductivity, I get that the compound will produce a temperature gradient of only 0.11 degree C per watt per 0.001" thickness, and the epoxy only 0.13 degree C per watt per 0.001" thickness. Arctic Alumina is more than adequate also, with roughly twice the thermal resistance of the Arctic Silver. So you can slop enough of either kind of epoxy on to make sure the P4 header is insulated from the light and still have a negligible temperature gradient.

I looked into using some 0.001" thick Kapton (polyimide) tape for insulation, but it ends up being around 6 degrees C per watt. Still not too bad, but the epoxy is so much better (50 times!) that I'm using it instead.

Arctic Silver, Arctic Alumina, and copper spacer slugs, as well as U bin P4 emitters, are available at the Sandwich Shoppe.

c_c


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## cmacclel (Jan 30, 2007)

Great Post CC 

Mac


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## EngrPaul (Jan 30, 2007)

I wonder if you're better off using compound vs. adhesive. I've been thinking the same thing, why not use compound and keep the emitter upgradeable and re-centereable.

I guess it comes down to how the compound will behave when the flashlight sees a G-force from the shock of being dropped. For epoxy, it might separate and no longer provide a thermal path. For compound, the emitter is only held by thin wires, and the shock may move the emitter or worse break a wire.

I tend to believe the epoxy is the safer route, quality epoxy SHOULD hold against just about any shock. 

I wonder if those flashlights dropped, causing breakage of the epoxy joint, had the reflector really close to the emitter. When the impact occurred, the reflector struck the emitter, instead of the emitter having enough mass inertia of it's own to generate a shearing force?


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## Mike abcd (Jan 30, 2007)

How about a thin layer of AS epoxy on the bottom of the SSC emitter for electrical insulation, let it set and then "mount" the emitter with regular AS?

I haven't gotten an SSC emitter yet to look at. Would anything stop you from carefully sanding down a layer of epoxy for smoothness and desired thickness before "mounting" it with AS?

No real benefit to C_C's method except being able to reuse the cheap copper spacer unless you weren't using one.

Mike


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## Curious_character (Jan 30, 2007)

After a little thought, it looks like the best method might be to first epoxy the copper slug to the light with enough epoxy to provide insulation. Then use compound instead of expoxy between the emitter and the copper slug. The advantages are that the mass of the slug isn't attached to the emitter, which should lessen the strain on the leads if the light is dropped. Also, the insulating property of the epoxy can easily be checked before soldering in the emitter -- I do this now, but it's hard to do without moving the emitter. And, like the method I was using (compound between the copper slug and light, and epoxy between emitter and copper slug), it allows positioning of the emitter after the epoxy has cured.

I'll try that method on the next light I mod. Hm, now I'm going to have to get some more Luxeon lights to mod. . .

c_c


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## EngrPaul (Jan 30, 2007)

c-c,

You're making a whole lot of sense. I think I'm going to use this procedure on a run of mods I'm going to be doing. The emitter has very little mass by itself. And if you get enough insulating material under the copper, and verified it, why make another layer of thermal resistance?


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## Curious_character (Jan 30, 2007)

Mike abcd said:


> No real benefit to C_C's method except being able to reuse the cheap copper spacer unless you weren't using one.
> 
> Mike


The benefit I saw over EngrPaul's method of epoxy on both sides of the copper slug was that I could position the emitter after the epoxy cured. But the alternate method I just proposed in another posting (expoxy the copper slug down and use compound between the emitter and slug) has the same advantage. You could also put epoxy on either side of the copper slug and sand it down flat as you suggest, then use compound on both sides and retain this advantage.

I doubt there's really any major benefit to one method over another, but I do like the ability to position the emitter after the epoxy has cured.

c_c


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## EngrPaul (Jan 30, 2007)

Another factor is the difference in expansion rates of the emitter and the copper slug. The emitter will heat up much quicker than the copper slug. This puts an in-plane stress on the adhesive joint. After a while, I suppose this could lead to failure of the joint to some degree (no pun intended). By having compound there instead, there will be no joint to degrade.


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## Kryosphinx (Jan 30, 2007)

Has anyone tried a P4 with an IMS20?


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## Gryloc (Jan 30, 2007)

Well I didn't think about external forces on the emitter and the epoxy bond. I guess that one of the biggest downfalls of the multiple emitter Maglite mods is the use of separate reflectors. You have to tighten the top lens holder down, which puts pressure on the reflectors and the emitters. It seems as though the IMS reflectors that I used were not meant for bare emitters (like it claims) because the legs on each reflector is not long enough. Therefore, the force is directed onto the emitter and not bypassed to the heatsink by the legs. 

Oh well. This is okay for me. I am still happy with the mod. I may replace the emitters in a few months anyway with the SSC P4, so I wont have to worry about having to break the emitters off now. Maybe I can create a spacer rings that will fill that little gap. I will stick with the AA Alumina epoxy (its all I got). I will figure out a way to ensure that the heatsink and the slugs of the LED is isolated. 

Anyone think of using the engine paint that features small bits of ceramic? I seen it at my local advance auto shop. Its commonly used on manifolds and headers. If you get a thin enough layer of this paint, it may insulate the LED while still transferring heat. Just an idea. I am sure it has been tried before. Well, good luck all with your projects...


-Tony


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## Mike abcd (Jan 30, 2007)

Curious_character said:


> The benefit I saw over EngrPaul's method of epoxy on both sides of the copper slug was that I could position the emitter after the epoxy cured. But the alternate method I just proposed in another posting (expoxy the copper slug down and use compound between the emitter and slug) has the same advantage. You could also put epoxy on either side of the copper slug and sand it down flat as you suggest, then use compound on both sides and retain this advantage.
> 
> I doubt there's really any major benefit to one method over another, but I do like the ability to position the emitter after the epoxy has cured.
> 
> c_c



Sorry, I just put that badly. I definitely see the benefit in your method. I was questioning the limited benefit in my suggestion of only using the epoxy to create a thin insulating layer and not gluing "anything together" but using AS as you suggested between the parts used.

Mike


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## Jon_L (Jan 30, 2007)

Anyone know of good electrically conductive cement? 

I'd like to ground my emitters and reverse the batteries.

How about epoxy mixed with aluminum or zink powder?


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## Gryloc (Jan 30, 2007)

I am sorry, but I think dealing with more layers will not be worth the trouble. I think you are worrying too much about a small and rare problem. Go ahead and epoxy the emitter to the original heatsink. There should be plenty of time (a few minutes) to position the LED during the cure time. I have had some good luck with electrical isolation of my LEDs with AA epoxy. My emitters broke loose (but stayed in place against the heatsink) because of the odd stresses on the emitter from the reflectors. The emitter by itself shouldn't have that much momentum in a drop to do harm, just make sure both surfaces are prepped and you have the exact ratio of adhesive and thermal parts. If you add too much of the thin part of the adhesive, the bond will we weaker. 

This is just my thought.

-Tony


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## WeLight (Jan 30, 2007)

I am a Cree distributor so let me state that to ensure my bias is established.

I find it interesting that both Cree and SSC are using the EZ1000 die platform and I find it equally interesting that Cree has only just announced the XLamp is now qualified for 1Amp usage. Clearly the thermal constraints related to qualification required some significant work to ensure the XLamp house was in order to support 1 Amp. Some of this thread content would suggest that SSC may not have been quite as rigourous in their development

Marketing driving Engineering again perhaps
Cheers
Wl


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## NewBie (Feb 3, 2007)

Remember, just how thin of a layer 0.001" actually is. A lot of paper is in the order of 0.003" thick.

Besides the stresses of metals at different temperatures, also consider that the CTE of epoxy is quite different than copper and aluminum, and it, itself also expands and contracts. Just food for thought. As I said in the epoxy thread, proper surface prep and mixing is everything...


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## NewBie (Feb 8, 2007)

Update.

I have a sample of just one Seoul P4 that I've ran for three weeks now, on that rather extreme heatsink shown earlier in the thread. Remember this is just a sample of *ONLY* one.

Anyhow, I've been planning on setting up a batch of these, as well as other LEDs from other manufacturers, for a long term brightness drop over time test. This ONE LED though has dropped in output in about 500 hours now, by about 10%.

I'd planned on waiting until I got batches all set up, before I mentioned this, but I was reading an article today, which toggled something in the brain housing group. An excerpt from the article:
"Chromaticity shift is not limited to warm white LEDs. Seoul's new P4 power LED package has a nominal CCT of 6500 K, and a typical output of 85 lm at 350 mA, equivalent to 76 lm/W. Elsewhere on the same P4 datasheet, there is a footnote to say that "the chromaticity coordinate of the LEDs can shift approximately x = 0.02, y = 0.03 in the direction of blue 1000 hours later." So during that time period the CCT could shift to approximately 8200 K. These figures suggest that Seoul's phosphor is very efficient, hence the excellent luminous flux and efficacy, but is not particularly stable over time."
http://ledsmagazine.com/articles/features/4/2/1/1

I'd remembered that on the datasheet, but it did not register as 1,000 hours when I read it. I looked it up, and they had it correct, it is at the bottom, in the orange box, as Caution number 2.

So, I hurried home from work, and took a look and realized the part has shifted from the very nice white it used to be, to a definite purplish looking white. This might also explain the drop in light output that I am seeing.

The amount of shift they are talking about is demonstrated as an example on this chart:







As far as flashlights, thats a lot of flashlight time, imho.

Has anyone been running these things and have 1000 hours on them yet, and could talk about their experience with them?


.


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## tebore (Feb 8, 2007)

^^ Was this the LED on the super big copper heatsink? What was the drive level on this LED?


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## Billson (Feb 9, 2007)

Newbie,

What current are you running your test setup at?


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## easilyled (Feb 9, 2007)

Even after a drop in output of 10%, after 500 hours, this is probably
still similar to the output of a *new* Cree P4 bin, since the SSC-P4-U
is at least 10% more to start with, if not more.

This needs to be born in mind.

Likewise in 500 hours, to go from slightly warm to slightly cool doesn't
strike me as a disaster.

However, with this knowledge its probably judicicous to select WO or
warmer tints from the start.


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## Brum (Feb 9, 2007)

easilyled said:


> Even after a drop in output of 10%, after 500 hours, this is probably
> still similar to the output of a *new* Cree P4 bin, since the SSC-P4-U
> is at least 10% more to start with, if not more.
> 
> ...


But ARE the SSC's brighter compared to a Cree? It's nice that they state that in their specsheets, but they dont have any verification (unlike Cree's NIST testing). And the graphs we've seen from Newbie indicate that theres very little difference, and if you include the power draw (the XR-E has a lower Vf, so less power consumed at the same current) the difference is even smaller.
About the tint shift: it might not bother us as flashlight freaks, but where the LEDs are used continiously (ie fixed lighting) the tint shift is unacceptable, since after a month of use the nice warm white has dissappeared. And fixed lighting is the main market, us flashlight freaks just make a few percent (-points) of the total LED market.


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## bullinchinashop (Feb 9, 2007)

So it _MIGHT_ have a ring or two. BFD
What is the real point of these led's? Are they brighter? More efficient? 
I started to get a Seoul light from DealExtreme but I can't see any real advantage to getting this vs another Q3.
Is everyone getting excited about these things because they're new or are they actually that much better than a LUX 3 or LUX 5?


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## easilyled (Feb 9, 2007)

Brum said:


> But ARE the SSC's brighter compared to a Cree? It's nice that they state that in their specsheets, but they dont have any verification (unlike Cree's NIST testing). And the graphs we've seen from Newbie indicate that theres very little difference, and if you include the power draw (the XR-E has a lower Vf, so less power consumed at the same current) the difference is even smaller.
> About the tint shift: it might not bother us as flashlight freaks, but where the LEDs are used continiously (ie fixed lighting) the tint shift is unacceptable, since after a month of use the nice warm white has dissappeared. And fixed lighting is the main market, us flashlight freaks just make a few percent (-points) of the total LED market.



Yes - they definitely seem brighter to me.

Some of Newbie's graphs *do* back this up.

My Seoul-P4-U on a Nexgen750 is considerably brighter than my
Cree-XRE on GD825 (even though the cree is driven harder)

I was commenting on the tint shift from a flashlight point of view, but
even in fixed lighting, will it really make a big difference if it shifts from
white (on the slightly yellow side) to white (on the slightly blue side)?

To be honest I don't really care about its use in fixed lighting at the moment
though.


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## easilyled (Feb 9, 2007)

bullinchinashop said:


> So it _MIGHT_ have a ring or two. BFD
> What is the real point of these led's? Are they brighter? More efficient?
> I started to get a Seoul light from DealExtreme but I can't see any real advantage to getting this vs another Q3.
> Is everyone getting excited about these things because they're new or are they actually that much better than a LUX 3 or LUX 5?



The Seoul and Cree-XRE's are just about twice as bright as lux3's
for the same power output. They're still brighter than lux 5's at about
half the power output.

That is a BFD to flashlight enthusiasts seeing the biggest leap in
led efficiency in led's short history.


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## bullinchinashop (Feb 9, 2007)

easilyled said:


> The Seoul and Cree-XRE's are just about twice as bright as lux3's
> for the same power output. They're still brighter than lux 5's at about
> half the power output.
> 
> ...



Thanks. I haven't been around as much as I used to be & I'm a bit behind on my information on Seouls. I think I just might have to get that light fromDealExtreme.


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## BPH (Feb 9, 2007)

I think NewBie’s previous testing does show the Seoul has significantly more lumen output (lumen/watt).


His excellent and thorough tests appear to measure “intensity”, which I assume is on axis, with units like Lux; lumens per square meter (If this is not the case, please disregard the remainder of this email).


The Cree has a much narrower beam pattern than the Seoul, so even if it measured the same intensity on axis, the Cree would be putting out less lumens due to the narrow beam pattern. I did some very quick calculations, which conclude if the on axis beam intensity is measure to be equal for a Cree and Seoul; the Seoul will be putting out much more total lumens (based on radiation patterns provide in the relevant PDF documents).


Also of critical importance is optics, so your really need to test a prototypes of each for the intended application to determine the best solution.


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## NewBie (Feb 11, 2007)

NewBie said:


> Okay, well, I tested a second CREE, which is #2 on the overkill heatsink.
> 
> CREE #1 is already mounted on a 2" by 3" by 0.165" piece of copper sheetmetal only.
> 
> ...






NewBie said:


> Seoul has nice projected reliability and life time graphs, one really nice thing about it, is later in the presentation, they show the effects of what a junction temperature of 90C does to the lifetime of their parts:
> http://www.essc.co.kr/_HOMEPAGE/hom...Reliability.pdf



Has anyone seen any published information on the P4 like this? Since I'm seening a relatively dramatic drop in light output (which could in part be caused by the significant spectral shift in white tint) I'd be really interested in seeing similiar tests on the P4. Also, any information which includes the tint shift over time on a graph would be handy. Anyone know specificially, which phosphor this new phosphor is that they are using in the Seoul P4, which shifts around in color over such a relatively short time, actually is? 




tebore said:


> ^^ Was this the LED on the super big copper heatsink? What was the drive level on this LED?



See below:









BPH said:


> I think NewBie’s previous testing does show the Seoul has significantly more lumen output (lumen/watt).
> 
> 
> His excellent and thorough tests appear to measure “intensity”, which I assume is on axis, with units like Lux; lumens per square meter (If this is not the case, please disregard the remainder of this email).
> ...




One **really* *really** needs to go back and read a thread from the beginning, instead of jumping into the middle of things with assumptions, it will make life easier for both of us. See the first thread post I quoted.

No, intensity does not infer that I used a light meter at a given distance. Nor did I use a true integrating sphere. I used a white plastic paint bucket, to help gather the light. I used intensity, since it is not really open lux into space, nor is it a absolute total lumens result from an integrating sphere. I've been doing some testing with different coatings inside the bucket and other shapes, like boxes, buckets, spheres, and it is quite interesting. 
-Shinny white paint/plastic gloss coatings can give certain beam distributions much higher readings than others. 
-Flat white paints like you typically get for bright white house paints ~85% reflectivity, have almost the opposite effect. 
-The amount of light a paint absorbs also has an effect.
-Sensor placement in non-spherical integrating solutions has a decent effect depending on light distribution.
-For more accurate measurements, there should be no direct light path from the source to the sensor. Professional integrating spheres have a baffle that blocks any direct light path.
-Different paints have different reflectivity curves, especially consumer/commercial grade paints which have cheap filler materials, and the reflectivity can aid/hurt different color bins differently.
-A single coating of paint is not sufficient. It takes multiple layers. I did a test with a clear glass and painted it. When you blast it with the light from one of these higher output flashlights, it is pretty amazing, how thick the paint needs to be, before you stop seeing the light pass thru.
-You really want a sphere...

I've got some paint that cost 250 dollars for a jar, that I'd like to use for a home-built integrating sphere, but I haven't found a decent 24" sphere to start it all off with. I have had it for a long time, the search continues.

Of particular note, light meters only approximate the human eye. Earlier I mentioned that this is one of the problems or caveats with this testing presented here. And different light meters respond differently, to different white tint bins, and will favor some bins over others, depending on their actual sensor response. So, when comparing LEDs for absolutes, not only do you need to have two LEDs that are close in tint to the human eye, they also need to have an actual spectral output that matches, otherwise you get further errors out of a light meter. For this reason, actual integrating spheres use a sensor that is responsive to the spectrum, where you can see relative output at each wavelength. Anything that uses a simple light meter is just a ballpark- not absolute.

Also, in comparing two LEDs for absolutes, you need to have them mounted similarly. You can't use thermal paste on one to the heatsink, then take one that is mounted on cheap China MCPCB, and then thermal paste that to the same heatsink. You need to offer the same thermal scenario for each.


Anyhow, my tests didn't use a simple lux meter, nor a perfect integrating sphere, more of a hybrid. Depending on how I collect the light, I can make one look better than the other (Seoul or CREE). Without a true integrating sphere and a sensor that can indicate output at each wavelength, trying to make absolute comparisions is quite futile.

With the Seoul P4 shifting around in color and lm/W so quickly in time (as indicated on it's datasheet and now what I see), due to this new type of specific phosphor they are using, we add a whole new dimension of things to worry about. For typical folks, who don't go thru a couple of batteries every week, this is less of a concern. For power users, or for fixed lighting/automotive headlights and such, this is something one really needs to look into very carefully. 

In the past, McGizmo has shown how different tints have a surprisingly important effect on color rendering outdoors. Others have done similar tests. The difference between a XO and a X1 bin, is quite surprising, even though they are just one bin apart. In the case of the Seoul P4 over time, we are changing not just left and right (ratio of red to blue), but also moving a large distance vertically (ratio of red+blue to green). At one point, the preference that a number of folks had for outdoor flashlights was the green tinted X1, since it over-emphasized greens. For others, they liked XO or even a cooler white. Yet others preferred a warm VO. To each his own. The human eye changes as we age, due to the lens actually turning brown, and yes, the human eye lens actually looks brown when removed. There is a thread I posted this information on cpf. Something that looks like a icy cold white to a kid at 16, can look warm white to someone that is past retirement age. So, each can argue over what "perfect white" appears to them, and they'd both be right. Such is the nature of the human condition...

One could even argue for various tints, depending on what they wanted to see more. If you want to see green vegetation, something with more green would be better. If one wanted to seen browns more, than something warmer would be better. If one wanted something white to stand out in the forest, bluish tints would be better in many forests. It is interesting what you can do with light, when you have control over the light spectrum, and how you can make certain things stand out from the rest. You can also make things stand out by making them black against the background. Essentially, the name of the game is to increase the contrast between what you want to see and what you don't. The human eye is really good at picking up contrasts.

Anyhow, the LED under test has now dropped from a reading of 310 on that chart to 270 now. The current is measured the same in both, to within 0.1% on the meter reading. The tint has visibly shifted very considerably, and is easily apparent- no need to compare against anything, you can look at it and tell it is purple white now (not cold white or even blue white, purple white). It was a rather warm white or even yellowish white when compared to normal while LEDs. I suspect that with more of the light output shifting towards blue and red (together they make purple), that since the measurement sensor and the human eye are more sensitive to green, this is the real reason for the actual light output loss- spectral shift as the phosphor degrades.


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## NewBie (Feb 12, 2007)

Billson said:


> Newbie,
> 
> What current are you running your test setup at?



1000mA on that big monster heatsink above.


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## BPH (Feb 12, 2007)

NewBie,
I have done my best to follow the thread, but I have missed a few comments, and didn't see your note on your hybrid integrating sphere.

My main point/question was the Other people are interpreting your data (again, thanks for providing it) to suggest that the Cree is producing nearly the same output as the Seoul, and I was commenting on the validity of this based on the different beam patterns (and test set-up).

So, my question is; from your data, can you make any reasonable guess as to the relative total lumen output between the Cree and Seoul chips you tested?

Thanks,
BPH


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## chimo (Feb 12, 2007)

Seoul definitely has a different phosphor mix. 

Here is a comparison with some Cree and Luxeons. The top photo is just taken in daylight. The bottom one was taken at the same time but has been illuminated by a 1W CreeUV light. I had to move the UV source a fair ways back so the Seoul phosphor would not saturate the image.




Paul


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## Kinnza (Feb 12, 2007)

Newbie said:


> Anyhow, the LED under test has now dropped from a reading of 310 on that chart to 270 now. The current is measured the same in both, to within 0.1% on the meter reading. The tint has visibly shifted very considerably, and is easily apparent- no need to compare against anything, you can look at it and tell it is purple white now (not cold white or even blue white, purple white)



If the tint shift is so noticiable, likely the output drop in lux reading is mostly due to it, meaning that about 1watt of radiometric power is emited, but with a luminous efficacy of 310 lm/w with the original tint, and 270 lm/w when it shifted.

If the shift is both to the blue and the red, the luminous efficacy may be easily higher than those 40lm/w. In contrast, the CRI should improve as consecuence. This trade off is very usual, but not in the same product. Glad you aware us, *Newbie*, really is something that SSC had to note. IMO, isnt a bad trade off, but the fact is P4's photometric efficiency is lower than announced when it reach a given (short) time use.

So there is a photometric output drop together with CRI improvement, but probably the radiometric output is somewhat stable. Impossible to say without a spectrometer, but if the tint shift is so noticiable, i believe that this analysis is reasonable. Of course, its impossible to say how much of the output drop is due to tint shift and how much of radiometric output degradation.

Personally, i like that kynd of tint (purplish), so im interested in this phospor for home use. Definitively, id like to know more about it. For me the main problem with the P4 is the gummy dome. IMHO, it make it just a good choice for enclosed lights.



BHP said:


> So, my question is; from your data, can you make any reasonable guess as to the relative total lumen output between the Cree and Seoul chips you tested?


 
As far as i can see it, it was already done along the thread. Newbie has explained in the last post why he cant get more accuracy than he had already showed. With this limitation in mind, the graph in the last Newbie's post show the relative emission (refered to watts consumed instead of current drawed, wich is more accurate than anything).



> I've got some paint that cost 250 dollars for a jar, that I'd like to use for a home-built integrating sphere, but I haven't found a decent 24" sphere to start it all off with. I have had it for a long time, the search continues.


 
We are in the same boat  . If you find it, please tell me :laughing: . For the coating, i suggest you a 50/50 mix (by weight) of latex flat white paint and BaSO4 (Barium sulphate) (adding a bit of water make the mix more manegeable, its very dense). It had a pure lambertian reflection and excelent reflectance between 430 and 800nm. In most of the visible range, its just about 2% less than spectralon. The white paint only degrades reflectivity at 430nm or lower, and current blue/white chips emits very little in that range. From 430 to 700nm, differential reflectivity is very small, ranging from 96 to 98%.


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## BPH (Feb 12, 2007)

I'll try again (and then stop bothering you'll). I don't think I was able to make myself clear. 

Can a reasonable conclusion be drawn from NewBie's testing as to if the Cree or Seoul has more Total lumen output? (that would be either yes or no)

I assume the answer is not really, too close to call. It could go either way depending on how NewBie's hybrid integrating sphere favors the particular radiation pattern of the emitter and other testing details.
-BPH


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## Calina (Feb 12, 2007)

chimo said:


> Seoul definitely has a different phosphor mix.
> 
> Here is a comparison with some Cree and Luxeons. The top photo is just taken in daylight. The bottom one was taken at the same time but has been illuminated by a 1W CreeUV light. I had to move the UV source a fair ways back so the Seoul phosphor would not saturate the image.
> 
> Paul


 
Wow, it glows  ! Does this means that GITD buttons and O'rings are unnecessary with these lights?


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## chimo (Feb 12, 2007)

Calina said:


> Wow, it glows  ! Does this means that GID buttons and O'rings are unnecessary with these lights?



It doesn't stay glowing. The phosphor is being excited by a UV light I was shining on them. It glows a *lot* brighter than the other phosphors.


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## NewBie (Feb 13, 2007)

BPH said:


> I'll try again (and then stop bothering you'll). I don't think I was able to make myself clear.
> 
> Can a reasonable conclusion be drawn from NewBie's testing as to if the Cree or Seoul has more Total lumen output? (that would be either yes or no)
> 
> ...



With the parts I've managed to get my hands on, I'd tend to believe the Seoul P4 is a tad more efficient, once you look at Watts consumed, *at least when it is new*.

One of the falacies is that I've seen, folks pick a bottom binned P2 CREE, and then snag a nice U bin Seoul, and claim smackdown. Thats like picking an R binned Luxeon III and a U bin Seoul P4- of course, they are from different bins, quite obviously one will be a lot more efficient.

Some folks are attempting to measure accurate lumens with a typical light meter. Differences in color bins can cause considerable errors, and lead to erronous results. Even differences in spectral output between different phosphors can add error.

This would be considered a very high end photodiode, that has a much better color filter on it than one finds in many light meters:
http://www.vishay.com/docs/81519/81519.pdf

At the bottom of page 3, figure 5, you will see Vlambda eye-this is the human eye response. The black line is the actual photodiode, and it's response curve to light. Notice the large margin of error vs. wavelength for this part, when compared to the human eye. This where large errors can creep in.

I've seen folks compare an LED mounted on a MCPCB to one direct mounted on a copper plate. When you compare in this fashion, obviously the MCPCB will measure a tad lower, especially with the higher profit margin MCPCBs. To be fair, it is best to give them an equal thermal solution.

Power is what the LED is going to use in a flashlight, so you really want to look at Power, which is Volts * Amps. Current only can be rather misleading.

Besides shifting color in a relatively short time, and the loss of lumens, the Seoul P4 LEDs I've tested, also shift more in color with changes temperature than most white LEDs I've tested.

Some folks like to claim that this LED is worst, best, or whatever. Nothing wrong with the LED, it is just different, and different trade-offs were made in it's design as compared to other LEDs. Some of the trade-offs will be a positive thing, and some will be a negative thing. It all depends upon your goals, application, and such. It is nice to have a variety of choices for power LEDs these days.


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## wojtek_pl (Feb 13, 2007)

NewBie said:


> 1000mA on that big monster heatsink above.


I wonder if tint change would happen so fast with less amperage... Say 750 mA...
In general... this doesn't look good as reliability goes...


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## NewBie (Feb 13, 2007)

The tint shift should be less with less current over time, but this is not something I've tested. 

One of the large factors for tint shift over time is the die temperature, and it's affect on the phosphor. As I recall, the LED slug is held below 30C, the exact number should be mentioned earlier in the thread. This part has been held rather cool, due to the excessive heatsinking, and the thermal resistance to the LED die is very low in this part, so I doubt that is much of a contributor for this LED.

The datasheet cautions about the shift, but does not give an actual specific cause for it.


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## BPH (Feb 13, 2007)

Measurements with tint errors:
I am most interested in doing field pattern tests on completely assembled systems. So I will be testing lux (lumens/sq.meter). There seems to be some good Spectral Response filters out there on ExTech light meters. I am looking at purchasing either the EA31 or EA33, unfortunately, neither has a PC connection but otherwise they look good. Here is page from their pdf;


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## NewBie (Feb 13, 2007)

I didn't notice Extech's new meters have a "precision" sensor and filter.

Very nice BPH!

Now all we need is a model that has this sensor in it, plus a PC hook-up.


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## NewBie (Feb 17, 2007)

I did some spectral scans of the Seoul P4 and CREE XR-E @ 700mA:







Un-marked up:







Both devices were new at the time of testing. You'll note the different phosphor response of the two LEDs. The Seoul has more yellow, significantly less "cyan-green", and slightly less red. The blue is slightly deeper on the Seoul, but this spot moves around a bit from part to part, depending on the die. The eye has difficulty noting wavelength differences at 460-470nm range anyhow.

Over temperature, @ 750mA, the majority of the color shift occurs when the slug temperature goes above 40C:


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## Nereus (Feb 18, 2007)

Newbie, thanks again for excellent info! I have some questions about your newest graphs:
- Seoul seems to have deeper valleys and higher peaks in its spectral distribution than Cree. Does this mean that Cree has better CRI?
- I have always wondered how an earth Seoul can be slightly more efficient than Cree even though they use exactly the same die. Could it be that Seoul has traded some CRI to efficiency?
- I have understood that overdriving makes white leds more blue because under OD there is "too much" blue light for phosphor to be transformed to other colours. However, your graph tells me that there might be thermal issues as well: when OD heats the phosphor up, its ability to transform blue to other colors suffer. Am I right?

Thanks!

-N


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## NewBie (Feb 19, 2007)

I do not know what their intentions are.

Apparently this higher efficiency phosphor doesn't hold up as long, and is more temperature sensitive. The datasheet also has a warning about how the part shifts a bunch towards the blue in the first 1000 hours.

If you look at jtr1962's white lumen testing thread, you will see the Cree P4 bin nearly matches the Seoul P4 U bin. Where everyone got astray, is that they were looking at a bottom end bin XR-E P2 bin and comparing it with a top end Seoul P4 U bin. Do the comparisions yourself:
http://candlepowerforums.com/vb/showpost.php?p=1858937&postcount=116


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## bombelman (Feb 19, 2007)

Not sure this has been posted before, but difficult to look for after 300+ posts 
Are there any nice side-by-side temperature graphs at different drive-currents ?

BTW, awesome reasearch, great job !


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## bombelman (Mar 3, 2007)




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## Led_Blind (Mar 19, 2007)

Howdie.... Remember the Lux's having the die cup loose its plating? I think the seul leds have the same behaviour...

I have a HDS modded with P4 since the first Seuls came available (2 months??). Being a true flashaholic i have runt this light as the bedroom light (on max) for one full 18650 almost every night (2-3 hrs) 

Now looking at the led, the area around the phosphor coat has gone all coppery. Has any one noticed this?


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