# Dissecting an MC-E



## saabluster (Jan 23, 2009)

I don't have a lot of time right now to go into a lot of detail but I wanted to share some pictures I have taken of an MC-E that was blown because it was run without having a heatsink. This is the LED given to me by Aircraft800 to do some "research" with. So thank you very much Aircraft800! 

I have much more work to do and actually bought a digital microscope just for this project. When I can find more time I will continue this thread with those pictures but for now I will post the ones I took with my camera.

Nothing seems too amiss looking at this picture but....






The LED got so hot that the dies unsoldered themselves. This is a view of the glass dome and the two dies that stuck to the gel. You are looking at the underside of the dies.
























This really was very interesting as there was three different failures all in the same package. Two dies unsoldered and stuck to the gel. One more unsoldered itself but managed to keep its bond wires intact. Its the one "standing" up. The bond wires are holding it there. The other one stayed soldered but had the phosphor stick to the gel. 






Notice the die that still has the bond wires attached? I wonder what would happen if you powered it up?











*Very* interesting! I plan to try and take the good die out of this package and mount it directly to a piece of solid silver with my special epoxy. More will come when I can find the time.


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## LED_Thrift (Jan 23, 2009)

Cool and interesting pictures. Thanks for posting this.


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## cerberuss (Jan 23, 2009)

Really interesting post, I was wondering... if one had to take the dome off a good mc-e... ...would that then change the optical characteristics and Possibly make it more of a point source source of light... and behave better in reflectors.. allowing for better throw?

Just wondering... :thinking:

nevermind... found the answer in another thread... throw increases but overall brightness reduces


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## spencer (Jan 23, 2009)

Looks really cool. I will be looking forward to updates.


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## Aircraft800 (Jan 24, 2009)

Unbelievable Pictures Michael! I like the new Microscope. How thick is that dome? I think that a flat top would greatly improve the optical characteristics of the MC-E for our purposes. Is there enough material to polish it down flat on top? The dome seems to exagerate the space between the dies, expecially considering it's appears smaller that the P7 which doesn't have as much of a problem controling.


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## saabluster (Jan 24, 2009)

Aircraft800 said:


> Unbelievable Pictures Michael! I like the new Microscope. How thick is that dome? I think that a flat top would greatly improve the optical characteristics of the MC-E for our purposes. Is there enough material to polish it down flat on top? The dome seems to exagerate the space between the dies, expecially considering it's appears smaller that the P7 which doesn't have as much of a problem controling.


Thanks. These pictures were actually done with just my camera and an aspheric lens I had laying around. There will be more to come. The dome is exactly like the one on the XR-E in that the base of the dome where it meets the package is where it stops. We have been discussing the optical issues in this thread. Polishing or sanding are not really an option. Not saying it couldn't be done there are just easier ways to accomplish this.


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## Ryanrpm (Jan 24, 2009)

saabluster said:


> Thanks. These pictures were actually done with just my camera and an aspheric lens I had laying around.




I bet you didn't have to search hard to find it! I'm sure you have more than one laying around also.


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## saabluster (Jan 24, 2009)

Ryanrpm said:


> I bet you didn't have to search hard to find it! I'm sure you have more than one laying around also.


Yeah I have a "few".


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## TexLite (Jan 24, 2009)

Great job on the dissection and the pics!

Is the silicone interface viscous or is it "set"?

Thanks,
Michael


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## saabluster (Jan 25, 2009)

TexLite said:


> Great job on the dissection and the pics!
> 
> Is the silicone interface viscous or is it "set"?
> 
> ...


It is exactly like the XR-E. A gel.


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## 65535 (Jan 25, 2009)

Does that mean with medium physical force it would pop off? Say grinding the glass dome flat?


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## saabluster (Jan 25, 2009)

65535 said:


> Does that mean with medium physical force it would pop off? Say grinding the glass dome flat?


Just taking it to a piece of sandpaper would surely pop off the dome as it is the stickiness/suction created by the gel that holds it in place.


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## djipe (Jan 25, 2009)

saabluster said:


>



Columbo ! Where are you ? ? ? :candle:

Here we have a serial cree kiler 


Nices picts, Good work guy.


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## csshih (Jan 25, 2009)

That's not dissection.... it's vivisection!! that cree was still alive. murderer!!


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## saabluster (Jan 25, 2009)

csshih said:


> That's not dissection.... it's vivisection!! that cree was still alive. murderer!!


HE WAS DEAD WHEN I FOUND HIM! I SWEAR!








....Must destroy evidence


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## Gryloc (Jan 25, 2009)

saabluster said:


> I plan to try and take the good die out of this package and mount it directly to a piece of solid silver with my special epoxy. More will come when I can find the time.



Have you thought of attaching the single die to a heatpipe? Then you can solder the heatpipe (or epoxy it) into a standard finned heatsink laying around that has the proper hole size drilled into it. Soldering it could be tricky, but this "special epoxy" sounds like it could do the trick. Actually, could you tell us anything about this epoxy? I am guessing it is electrically conductive and could be applied thinly.

Congratulations on being able to get a single die with bond wires still attached to it. Its too bad that it meant losing an MC-E for it. I have a dome-less neutral white MC-E that is almost useless to me (not as bright), so it would be neat to see if I can harvest separate dies like this. Hmmm...

Just be careful when eclectically connecting those free bond wires. I learned from Newbie that if you would try to solder the fine gold wires, you will find that they will dissolve into the solder. It will take some sort of low-temperature bonding technique to eclectically connect them. How about low melting point solder (silver based?), electrically conductive epoxy, or mechanical clamps (like crimping a fixed piece of copper or aluminum around the bond wire). Please keep us informed on this. I am extremely interested in this. Back in the day, I created a thread asking if it is possible to de-solder XR-E dies (back in the P2/P4 days) to make a quad die emitter (ceramic substrate with 4 dies like the current MC-E). I had 3d drawings made up and had a plan, but lacked time, money, and skills to attach dies with bond wires and phosphor coating. Its in my thread history, but I do not have a link on hand now. Good luck!

-Tony


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## saabluster (Jan 25, 2009)

Gryloc said:


> Have you thought of attaching the single die to a heatpipe? Then you can solder the heatpipe (or epoxy it) into a standard finned heatsink laying around that has the proper hole size drilled into it. Soldering it could be tricky, but this "special epoxy" sounds like it could do the trick. Actually, could you tell us anything about this epoxy? I am guessing it is electrically conductive and could be applied thinly.
> 
> Congratulations on being able to get a single die with bond wires still attached to it. Its too bad that it meant losing an MC-E for it. I have a dome-less neutral white MC-E that is almost useless to me (not as bright), so it would be neat to see if I can harvest separate dies like this. Hmmm...
> 
> ...


Funny you mention the heatpipe idea. Last night I bought several heatpipes to do this very thing. I got to thinking about it and decided if I was going to do this I might as well go all out. Yes the epoxy is electrically conductive. Here is a PDF on it. I am using the 6030 hk with a thermal conductivity of 60 W/m°K. I remembered what newbie had said about soldering to the bond wires so I figured I could use my epoxy to also connect to the bond wires. I am trying to decided whether or not to encapsulate it in clear silicone(with no dome so the die size is small) or try and cool the top of the die with a liquid coolant. What do you think? I am going to try and put this in a DEFT so that may rule out the coolant idea but it sure is tempting.


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## saabluster (Jan 25, 2009)

One other idea I have had is to scrape off the phosphor Cree uses and coat the die in quantum dots. I have found several places where you can buy them but they are fairly expensive. If people wanted to go in on it together I might be able to do it but as it stands I cannot afford it at the moment. Sure would be cool wouldn't it?


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## R33E8 (Jan 25, 2009)

saabluster said:


> One other idea I have had is to scrape off the phosphor Cree uses and coat the die in quantum dots. I have found several places where you can buy them but they are fairly expensive. If people wanted to go in on it together I might be able to do it but as it stands I cannot afford it at the moment. Sure would be cool wouldn't it?



Another problem with quantum dots would be finding an appropriate epoxy that doesn't render them useless.. I think they have a problem with clumping together when mixed improperly or without the right substance..


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## saabluster (Jan 25, 2009)

R33E8 said:


> Another problem with quantum dots would be finding an appropriate epoxy that doesn't render them useless.. I think they have a problem with clumping together when mixed improperly or without the right substance..


I was not going to use an epoxy. I think it would be hard to find a clear epoxy that could handle the extremely high heat of the overdriving I plan on doing. If you know of one let me know. My thought was to use a 2 part clear silicone with a thinner added so that I could apply a very thin layer.


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## Youfoundnemo (Jan 26, 2009)

Quantum dots!!!????? someone please tell me this *M*****C*ree-*E*xterminator isnt becoming a comedian


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## R33E8 (Jan 26, 2009)

I guess I should have used a more general word instead of epoxy.. Anyways, I found the article about it.. 

http://www.physlink.com/News/071403QuantumDotLED.cfm



> "Doing this we had to take care not to alter the surface chemistry of the quantum dots in transition from solvent to encapsulant," says Thoma, who worked on the encapsulation portion of the project.





> However, a key technical issue in the encapsulation process had to be solved first. When altering the environment of the dots from a solvent to an encapsulant, the quantum dots would "clump up" or agglomerate, causing them to lose their light-emitting properties. By attaching the quantum dots to the "backbone" of the encapsulating polymer they are close, but not touching. This allows for an increase in efficiency from 10-20 percent to an amazing 60 percent, Thoma says.


I'll be talking to some professors in the next couple of weeks who have experience working with quantum dots.. I'll try to find out if they know a suitable method of coating the die with quantum dots..

Or maybe you could figure out how to do this:


> By attaching the quantum dots to the “backbone” of the encapsulating polymer they are close, but not touching. This allows for an increase in efficiency from 10-20 percent to an amazing 60 percent, Thoma says.


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## saabluster (Jan 26, 2009)

R33E8 said:


> I guess I should have used a more general word instead of epoxy.. Anyways, I found the article about it..
> 
> http://www.physlink.com/News/071403QuantumDotLED.cfm
> 
> ...


Thanks for taking note of that issue. I read that article fairly recently but had forgotten about the clumping problem. I would be very interested to hear what the professors have to say. Thank you very much for your input.


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## saabluster (Jan 26, 2009)

I just realized there will be an issue trying to copy what they did exactly. "By attaching the quantum dots to the "backbone" of the encapsulating polymer" They are using 5mm LEDs with an epoxy package. This will not work with these high power LEDs. The heat would blacken that epoxy in no time. I wonder if the same issues exist with silicone as an encapsulant? I'm curious what solvent is being used. Will it dry out if exposed to air? If so I could coat the die and then let it dry before applying the silicone. Just thinking "out loud".


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## jashhash (Jan 26, 2009)

quantum dots! The ideas proposed here seem to be more difficult than brain surgery. I like it. I've never heard of quantum dots before gota read up on that. In any case what you are proposing to do is to home brew a brighter, more efficient LED...


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## likeguymontag (Jan 26, 2009)

saabluster said:


> The heat would blacken that epoxy in no time. I wonder if the same issues exist with silicone as an encapsulant?



Silicone optical gel is used in recent power leds _because_ those same issues don't exist. I don't know if it's the same formulation as RTV, caulk, and silicone kitchenware, but that stuff stands up quite well to medium-high temperatures.

Epoxies, on the other hand, are sometimes recommended for building furniture that you want to be repairable. (If you use white/yellow wood glue you have to _completely_ clean out all the old glue before you repair a joint.) If you used epoxy, you can melt the broken joint with a heat gun, clean it up a bit, and reglue it.

So yes, some silicones have much better heat resistance than some epoxies.


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## saabluster (Jan 26, 2009)

likeguymontag said:


> Silicone optical gel is used in recent power leds _because_ those same issues don't exist. I don't know if it's the same formulation as RTV, caulk, and silicone kitchenware, but that stuff stands up quite well to medium-high temperatures.
> 
> Epoxies, on the other hand, are sometimes recommended for building furniture that you want to be repairable. (If you use white/yellow wood glue you have to _completely_ clean out all the old glue before you repair a joint.) If you used epoxy, you can melt the broken joint with a heat gun, clean it up a bit, and reglue it.
> 
> So yes, some silicones have much better heat resistance than some epoxies.


I think you misread my posts. I _know_ silicone can handle higher heat. Thats why I talked about using it. The stuff I use is not your home depot stuff either. The issues I was referring to was the clumping that happens when you mix the quantum dots with epoxy. I don't know what surface tension the silicone would have and whether or not the same will happen when I mix the dots in with the silicone.


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## EngrPaul (Jan 26, 2009)

Oh the humanity!


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## likeguymontag (Jan 26, 2009)

saabluster said:


> I think you misread my posts. I _know_ silicone can handle higher heat. Thats why I talked about using it. The stuff I use is not your home depot stuff either. The issues I was referring to was the clumping that happens when you mix the quantum dots with epoxy. I don't know what surface tension the silicone would have and whether or not the same will happen when I mix the dots in with the silicone.




Oops, pardon me.  I was skimming.


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## 65535 (Jan 26, 2009)

Hey saa, 

A thought; would a thin strong adhesive applied around the dome to glue it to the plastic base hold the dome on enough to grind and man handle the led?


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## saabluster (Jan 26, 2009)

65535 said:


> Hey saa,
> 
> A thought; would a thin strong adhesive applied around the dome to glue it to the plastic base hold the dome on enough to grind and man handle the led?


Its possible. One option to help grinding may be to get a diamond cutting wheel made for the dremel and use that to grind down the dome. If you used some type of adhesive to hold the dome in place this could work. To "polish" you could just put a coat of norland over the top to smooth it out.


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## saabluster (Jan 27, 2009)

One other thought with the quantum dots is whether to make it a conformal coating or mix it in a silicone blob over the die like SSC does. Personally I think it would be better to just conformal coat the die.


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## 65535 (Jan 27, 2009)

My other idea was simply to remove the dome clean up the die's completely and then make a level puddle of a norland optical adhesive or something to cover the phosphor and dies.


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## saabluster (Jan 27, 2009)

65535 said:


> My other idea was simply to remove the dome clean up the die's completely and then make a level puddle of a norland optical adhesive or something to cover the phosphor and dies.


The absolute max amount of heat it can handle is **125*°*C. It will see way over this with the overdriving I will be doing.


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## 65535 (Jan 27, 2009)

Well for you it may not work for us sain folk it might work pretty well. I'd say for you an optical grade silicone adhesive. temps are usually in the hundreds.

http://www.masterbond.com/tds/ms415.html


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## saabluster (Jan 27, 2009)

65535 said:


> I'd say for you an optical grade silicone adhesive. temps are usually in the hundreds.
> 
> http://www.masterbond.com/tds/ms415.html


 Silicone is the road I am looking to travel down. Thanks for the link.


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## PhantomPhoton (Jan 27, 2009)

Wow Saabluster, heatpipes and quantum dots... you have grand plans my friend.  You might end up bringing some of my dreams into reality.
Thanks for the pictures btw.


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## saabluster (Jan 27, 2009)

PhantomPhoton said:


> Wow Saabluster, heatpipes and quantum dots... you have grand plans my friend.  You might end up bringing some of my dreams into reality.
> Thanks for the pictures btw.


Your welcome. I like to think big. There will be some more pics when I get around to it.


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## 65535 (Jan 27, 2009)

Hey Saa if you're going to all this trouble you can try an idea I've had. Localize the phosphor material into the focusing area you like then find a way to expose it to the UV or w/e light emitted by the dies. optics or fibers or something
i think you can gain efficiency and easy of focus lighting up the phosphor away from the die.


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## saabluster (Jan 27, 2009)

65535 said:


> Hey Saa if you're going to all this trouble you can try an idea I've had. Localize the phosphor material into the focusing area you like then find a way to expose it to the UV or w/e light emitted by the dies. optics or fibers or something
> i think you can gain efficiency and easy of focus lighting up the phosphor away from the die.


Not sure I understand what you are saying. Try again and use small words.


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## 65535 (Jan 27, 2009)

Remote phosphor placement. Normally the phosphor is on the die pretty much, what if you used fiber optics or something to take the light the die produces and shine it on the phosphor but in a way that the phosphor could be closer to the focus area than an entire die.


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## LEDmodMan (Jan 29, 2009)

Reminds me of some of the destroyed Luxeon V's many years back. Heh heh. There were even a few of us who blew up "X" binned ones (the rarest of the rare). :green: Great pics BTW.

How sure are you guys that the Cree domes are made of glass? I can't find anything in the literature to support this. I know the domes on Luxeons were plastic of some sort. Just curious. TIA.


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## saabluster (Jan 29, 2009)

LEDmodMan said:


> How sure are you guys that the Cree domes are made of glass?


100%


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## LEDmodMan (Jan 29, 2009)

Wow, that's pretty sure then. Interesting. Glass should certainly pass more light than plastic in general. Thanks!

PS - Garland huh? I was in Saginaw for 5 1/2 years till summer '07. Too bad I never got to meet you!


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## saabluster (Jan 29, 2009)

LEDmodMan said:


> PS - Garland huh? I was in Saginaw for 5 1/2 years till summer '07. Too bad I never got to meet you!


Well if your ever back in town send me a PM.


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## Nemozoli (Feb 3, 2009)

65535 said:


> Hey saa,
> 
> A thought; would a thin strong adhesive applied around the dome to glue it to the plastic base hold the dome on enough to grind and man handle the led?



Hi!

I would say: it would hold the glass dome in place, because that is just what I had to do with my MC-E's. I was trying to put two LED's side by side each other, so that they would have a "mixed" throw beneath an aspherical glass lens. Whilst glueing the aspherical lens in place I noted that the solvent of the glue used (presumably the ethyl-acetate part) acted upon the silicone gel, separating it from the chips...  this was unpleasant news, never before has this glue done this before with any kind of LED I met...

So I got some "bubbles" in the LED with reflective (air-silicone) surfaces.
I cleaned some of the gel and tried to add a transparent epoxy to fix the glass domes, but it wouldn't tolerate the heat and soon became yellow-tinted, just like the light it let through. :shakehead

My next try was more successful: I peeled the tinted epoxy from the silicone gel and fixed the domes on their "perimeters" with a very strong two-component epoxy (this one seems to tolerate heat a lot better than the other one), while applying pressure (using a vise  ) to the domes to eliminate bubbles beneath them.

Now the glass domes are concrete-like set in place, I could even sand down part of one side of the domes to put them closer to each other. I wouldn't sand/polish down the glass dome, because it would prove to be quite a bit of a challenge to polish a perfectly smooth, flat lens-like surface on such a small piece of glass...

Keep up the good work!

Nemo


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## saabluster (Feb 11, 2009)

R33E8 said:


> I'll be talking to some professors in the next couple of weeks who have experience working with quantum dots.. I'll try to find out if they know a suitable method of coating the die with quantum dots..


 Just wondering if you have talked to them yet.


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## R33E8 (Feb 11, 2009)

Not yet sorry.. I'm supposed to be meeting with them to get involved in some research projects and the person organizing it is trying to find a time we are both free.. Hopefully soon though


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## R33E8 (Feb 12, 2009)

I'll be meeting with the professor who has experience with quantum dots tomorrow afternoon..:naughty:


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## saabluster (Feb 13, 2009)

R33E8 said:


> I'll be meeting with the professor who has experience with quantum dots tomorrow afternoon..:naughty:


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## R33E8 (Feb 13, 2009)

Well I have some bad news..

The bad news is the professor I talked to has no experience with applying quantum dots to things, only making them for medical purposes.. He doesn't seem to know too much about LEDs general but he does know the different parts when explained like the phosphor, semiconductor die, etc..

Some interesting news is the quantum dots they make emit a wide range of wavelengths that are like 100nm wide.. I think that would be good for LEDs...

Some cool news for me is that I may join his research team (currently only one other person on it) to help develop a way to use the quantum dots with LEDs... So maybe in the future I could help out a bit more once I understand them better..


Sorry I couldn't get any info that could help you for now...


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## Ryanrpm (Jun 7, 2009)

saabluster said:


> *Very* interesting! I plan to try and take the good die out of this package and mount it directly to a piece of solid silver with my special epoxy. More will come when I can find the time.




Just wondering of you've found the 'time'??:wave:


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## csshih (Jun 7, 2009)

.... unless he's destroyed the evidence!


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## saabluster (Jun 8, 2009)

Ryanrpm said:


> Just wondering of you've found the 'time'??:wave:


I'm waiting on some quantum dots before I do any more on this.


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## R33E8 (Jun 8, 2009)

saabluster said:


> I'm waiting on some quantum dots before I do any more on this.





If you are waiting on mine, I'm just trying to figure out a simple way to measure CRI from spectrometer readings before I continue fine tuning them.. Hopefully I should have a lot more time to do so over the summer ..


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## saabluster (Jun 8, 2009)

R33E8 said:


> If you are waiting on mine, I'm just trying to figure out a simple way to measure CRI from spectrometer readings before I continue fine tuning them.. Hopefully I should have a lot more time to do so over the summer ..


I am indeed waiting on yours. I even bought some special encapsulating silicone made for LEDs for this very project. No rush though as I am very busy at the moment.:thumbsup:


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## bshanahan14rulz (Jun 8, 2009)

what flavor quantom dots? you mean those little ice cream balls, right? :thinking:

cant wait, pics please!


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## Illum (Jun 8, 2009)

well...this certainly has stuffed the chip weevils in the can hasn't it...

you better clean up after yourself! those domes are semipermeable and its only a matter of time before the eggs gets attracted to those LEDs you have lying about:shrug:


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## HarryN (Jun 8, 2009)

A good method to place the dots is similar to what PL does - make it into a ceramic, them adhesive it on.

The other method, modeled after LEDEngin, is to put on a clear ceramic window, then put the phos / dots on that. Much easier.

The mixing of the dots (or phos) is really challenging, but it has been done before. In addition to clumping, they like to settle out. It is almost as if they will not wet. Perhaps if you find a silicone that is designed to adhere stongly to glass it would help.


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## saabluster (Sep 17, 2010)

Not that the MC-E is of much interest to anyone anymore but I just thought I'd add a couple pictures to this old thread. I have been harvesting LEDs and took this picture just to show how the MC-E is constructed a little better. The four dies are placed on a very thin ceramic chip that is metalized and then soldered down to the main copper heatsink. I also notice the use of multiple layers of silicone of varying index to improve light extraction. Nothing new there.


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## panicmechanic (Sep 18, 2010)

I also had the chance to play with an MC-E I had almost soldered to death already, it gives light only when pressure is applied to the dome. An ideal candidate to practice flattening the dome.
I simply clamped the star it is soldered to in the lathe, fixed a minitool with 30 mm diamond cutting disk to the tool support, then slowly ground the dome down at 500 and 10.000 rpm, respectively. No special glue, just slow and controlled movement with cool-down time in between.
As you can see, the glass began to break at the rim - I went down too far. Still lights up like before, with pressure, and the broken regions show up as reflections in the beam. 
Next I took an intact cold-white (pictured is a ground ww) and ground to around 1 mm of glass, nothing broke. Polished with fine grid paper and metal polish, done.
Light output did suffer though, as was to be expected. Without measuring equipment, so just a subjective view: the flat M-bin Cree falls behind a two-die Altilon that I have for testing, and that one isn't even the latest bin.


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