# luxeon rebel question



## capo (Jan 27, 2009)

hello,
can anyone explain to me wich and how is the easiest way to atempt rebel led on a star

thanks


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## georges80 (Jan 27, 2009)

capo said:


> hello,
> can anyone explain to me wich and how is the easiest way to atempt rebel led on a star
> 
> thanks



I assume you mean how to solder a Rebel to a compatible star base??

If so, then solder paste and a hot air tool works great. After doing more than 100 that way, it really is very easy to do.

Not on a star, but to 2oz copper PCB:







cheers,
george.


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## jeffosborne (Jan 27, 2009)

Hi capo,

I like to use Arctic Alumina thermally-conductive epoxy to mount the Rebel LED, and then scrape the mask off the copper traces on top of the LED and solder my wires there. If you do this, be sure to coat the two copper pads on the bottom of the LED with a thin coat of nail polish or other coating that will insulate the contacts from the metal heat sink you will adhere the LED to. Use lightweight solid wire to attach directly to the LED, as the contact area is so small. Here are some 80-lumen per watt neutral whites I am using for a freind's light fixture that has 5 candlestick type elements. 




The penny fits neatly into the top of the faux candlestick tubes. The hookup wire is 28 gauge solid.




Cheers,
Jeff


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## dudu84 (Jan 28, 2009)

Great idea!

I was looking for some sort of heatsink for my Cree P4 and the coins are just perfect: easy to find (who doesn't have coins? lol) and cheap 

Thanks a bunch! :thumbsup:


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## Icarus (Jan 29, 2009)

georges80 said:


> ....If so, then solder paste and a *hot air tool* works great. After doing more than 100 that way, it really is very easy to do.


George do you mean you're just using a heatgun?
What kind of solder past are you using?


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## georges80 (Jan 29, 2009)

Icarus said:


> George do you mean you're just using a heatgun?
> What kind of solder past are you using?



Hot air tool - not heatgun 

You need to be able to set the temperature and airflow of the heated air. I have used a good priced and decent performing all in one hot air tool:

http://www.circuitspecialists.com/prod.itml/icOid/8010

for the past couple of years. Used one at work too. Has been reliable and good bang for the buck.

Handy for heatshrink tubing to removing/replacing faulty IC's etc.

I just bought solder paste online (after some searching) at http://www.zeph.com/ there's a lot of interesting info on there and some videos of various soldering procedures. I just bought the solder paste there and a few tips to 'experiment' with.

For soldering the Rebel, the solderpaste and the hot air tool work VERY nicely. I run around 320C on the tool and just warm everything up and then concentrate the air stream around the edges of the Rebel. You can see the solderpaste start to melt, then go fully liquid and the Rebel floats/centers itself perfectly onto the pads (surface tension).

The solderpaste has the flux in with it - so all you need is a few dabs of solderpaste, tweezers to 'stick' the rebel down on the paste and then heat up with the hot air tool.

Of course being in Europe, you would need to source the solderpaste locally and due to your loony EU stuff it would likely have to be lead free too 

cheers,
george.


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## Blindasabat (Jan 30, 2009)

I see you used a 2005 penny for your close-up.

Pre-1983 pennies are copper, '83 & after are 98% zinc. Zinc is not a good heat sink. If you did at least one with a pre-83 penny, it'd be interesting to see if the Rebel on that one stayed cooler.


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## LukeA (Jan 30, 2009)

Blindasabat said:


> I see you used a 2005 penny for your close-up.
> 
> Pre-1983 pennies are copper, '83 & after are 98% zinc. Zinc is not a good heat sink. If you did at least one with a pre-83 penny, it'd be interesting to see if the Rebel on that one stayed cooler.



Pre-1982 pennies are all copper, some 1982 pennies are all copper. You have to file a little to see. All post-1982 are zinc cored. A heatsink made with a solid copper penny will have a significantly lower junction temperature than a zinc-cored penny.


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## Icarus (Jan 30, 2009)

georges80 said:


> Hot air tool - not heatgun
> 
> You need to be able to set the temperature and airflow of the heated air. I have used a good priced and decent performing all in one hot air tool:
> 
> ...


 
:thanks: George! :thumbsup:


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## Icarus (Feb 8, 2009)

georges80 said:


> Hot air tool - not heatgun
> 
> You need to be able to set the temperature and airflow of the heated air. I have used a good priced and decent performing all in one hot air tool:
> 
> ...


 
George,

What kind of solderpaste from zeph.com can you recommend for use with the hot air gun in your link?


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## georges80 (Feb 8, 2009)

Icarus said:


> George,
> 
> What kind of solderpaste from zeph.com can you recommend for use with the hot air gun in your link?



I chose http://www.zeph.com/zephpaste.htm it is the 63/37 solder that works really well. BUT not sure if it can be shipped to the lead free EU... It also ships with a cold pack, to keep the solder paste cold and extend its shelf life. I doubt the cold pack would last till it got to you - even if they could ship there.

Do they still sell lead based solder in the EU?

You may need to order the lead free version: http://www.zeph.com/lead-free_zerolead_no-lead_solder_paste_no-clean_rohs_compliant_10cc.htm

Note in both cases it is only the solder paste 'tube', you need to order the syringe tips and the plungers (the cheap plungers are just fine) separately. I bought a few of the medium tips since I wasn't sure what would work best. For the rebel I've been using the 'pink' tips which is their 18 Gauge size - seems to work fine.

If you decide to order through them, it would probably be a good idea to contact them and see what they say about shipping to the EU.

cheers,
george.


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## Icarus (Feb 24, 2009)

> Originally Posted by *georges80*
> Do they still sell lead based solder in the EU?


I don't think so... 

BTW I bought the hot air tool from circuitspecialists (they have a EU website as well).
And... although it was much more difficult :hairpull: I finally also found some solder paste locally. 

Thanks again for the help. :thumbsup:


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## Gryloc (Feb 24, 2009)

capo, you can also use a hotplate or a small oven to solder the Rebel. All these do is heat the heatsink to the temperature required to melt the solder paste, then the Rebel will float and even out. Once the solder paste melts and you see the emitter sink down a little, then immediately remove the heatsink from the source of heat. This is not the ideal way because you could accidentally overheat your emitter. In addition, when re-flow soldering these, you should have some kind of cycle where the temperature ramps up slowly initially, then ramps back down slowly afterwards. However, if you are trying to keep things cheap and simple, it works pretty well. 

There are three simple ways you can heat the Rebel. First is in a basic toaster oven (just keep an eye on everything through the window). Second is a hotplate, like the ones used in a lab. These can be pretty expensive, but you could make your own. I heard about people using their electric range tops, but that may be overkill, and possibly fatal to the emitter due to the extreme heat. Lastly, I have heard about someone using a standard iron (for clothing) that was mounted upside down. The temperature could be adjusted roughly, and the surface underneath is flat. Just make sure that you do not add any water to the iron for the steam feature.

I used a strange setup composed of my Weller soldering iron (mine is the digital soldering station) that has the tip of the soldering iron thermally connected to a small block of aluminum. I drilled a somewhat conical hole into the aluminum, then created a rig that pressed the soldering iron tip in to the hole. I monitored the temp of the aluminum block using a thermocouple. It is really nice because you can fine tune the temperature by adjusting the temperature control knob. I adjusted the temperature to about 10 degrees F above the temp that my solder will melt. All I had to do is set my MCPCB on the top of the aluminum block, and it will immediately start melting the solder. I positioned my emitters, then carefully lifted the MCPCB back off using pliers to let the solder cool.

I am sure that you would have better control over the soldering process if you use the heatgun. Thank you, George, for the link to that hot air gun. I will make a hot air gun my next tool investment. I always thought that they would be too expensive until now, but that is because I have only seen the models that have both a soldering iron and a hot air gun connected to the same base station. 

Finally, I got my solder paste from dealextreme (which ships to the EU I believe). It was cheap stuff, but it worked for me. However, the stuff from DX probably is not lead free, or even ROHS certified. In addition, it ships at room temperature, and I noticed that mine was slightly hardened when I got it. It still had a soft enough consistency to where I can spread it onto the copper contacts, though. It is working for me, but I havent soldered any SMD ICs with the stuff yet. If you cannot find solder paste, you could just pre-tin all the contacts with your solder of choice before heating. Well, happy modding, capo.


-Tony


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## bshanahan14rulz (Feb 25, 2009)

I had a XP-E to be soldered on an 8mm mcpcb. Because of the size of the mcpcb, I decided to try using my dinky 20W radiohut soldering iron. I tinned the three pads with just enough solder. I mean, barely tinned these pads, like, about as thick as cigarette box cardboard at the thickest point. Then I just held the iron on one of the solder pads for wires and waited until the solder melted on the other pads. dropped the xp-e on there, waited until it floated a little, then released heat. Worked like a charm, most professional-looking solder job I have ever accomplished! this was on a single-emitter 8mm (look at a ruler) round MCPCB. If what you are working on is bigger, you might need a different heat source.


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## chuckolson (Aug 29, 2010)

Thanks for all contributions to this very interesting thread. But it may not be necessary to do the soldering. Check out luxeonstar.com where for 7 - 8 bucks they will do the soldering and supply the Rebel led pre-mounted on a 10mm square base with topside terminals for wires. Just stick the base to your heat sink with a pre-cut double-stick thermal pad they also sell for about 35 cents apiece.

chuck


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