What's cooking good looking? My LEDs! How I re-flow emitters

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RaceR86
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What's cooking good looking? My LEDs! How I re-flow emitters

Others have shared their way of doing this. This is my way.

My highly professional re-flow setup. Silly

The gear:
-A dirty “cooking plate” from the garage
-Two tweezers (one could do)
-Solder sucking thing, just in case I add a bit too much solder
-IR gun, to monitor the heat (You don’t want it to be warmer than needed. The solder should melt, but not any higher temperature. That could damage the LED)
-DMM, just to double check it was a 100% successful re flow.
-Aluminium plate (sorry, not pictured)

The ingredients:
-Solder
-Copper MCPCB (or new MCPCB of some sort)
-Emitter on star or bare emitter

My cooking recipe:
-Throw on the copper MCPCB. Get the heat up to a level where the solder will melt on the three traces where the emitter should sit. You only need a little bit of solder to cover the surface where the emitter sits.
-Throw on the MCPCB that the emitter sits on (if you don’t have a bare emitter). Once the emitter gets loose, use a tweezer and move it over to the copper MCPCB. Make sure to put it on the right way (+ to +), not sideways or anything either.
-Make sure the emitter sits nice and flat. Take of the copper MCPCB and put in gently on an aluminium plate or something (not pictured), quickly use the tweezer to push it down on the MCPCB without touching the dome.
-Once cooled properly. Test it with a DMM. Put it on the setting where you check if there is contact between stuff. The beep thingy. Silly Connect the positive wire from the DMM to the positive on the led. Negative to negative. It it should light up a little bit.
-Success! Dinners ready! Smile

100% success rate with this setup. Its real easy and fun! Smile

BLF LED database – collaboration spreadsheet and latest news about where to buy LEDs
http://budgetlightforum.com/node/19342

Edited by: RaceR86 on 12/25/2013 - 16:48
DB Custom
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Do you go ahead and put a dot of green paint on the hot plate control switch to indicate the sweet spot so you don’t have to look for it next time? Or would that be reliable?

Pulled the trigger on a IR gun just last night, didn’t even think about using it in this application! Thanks!

RaceR86
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The crappy plate only have 4 modes.. Silly
Mode 3/4 is nice for getting the heat up, but too hot if it stays for for more than 30 sec or so. If its stays too long on 2/4 the temperature it will go slightly below where it is needed to be.
When I apply the solder I often use it on the 3/4 setting. Then turn it down or off afterwards. Needs a bit more heat to gets the soldier attached than to just keep it “wet” on the MCPCB.
I have to change up and down sometimes to stay in the sweetspot. The IR gun is nice to have then.. Just to have a better feel of the heat and to avoid overheating the LED.

It may not sound super easy when I explain it, but its real simple and fast to do. Smile

BLF LED database – collaboration spreadsheet and latest news about where to buy LEDs
http://budgetlightforum.com/node/19342

MRsDNF
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Nice racer86. My pill, star and led are in the mail. Do you reckon they will be done in the next couple off weeks? Thanks buddy.

 

djozz quotes, "it came with chinese lettering that is chinese to me".

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Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

FlashPilot
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Yummy! I can smell the tasty aroma of smoldering flux from here.

RaceR86
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What tasty aroma of flux? Cant smell such when that cooking plate gets hots.. All sorts of aromas coming from that.. Heated rust, heated dust, heated oil, heated sand… Its all a part of the charm. Big Smile

BLF LED database – collaboration spreadsheet and latest news about where to buy LEDs
http://budgetlightforum.com/node/19342

Crux
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This technique works quite well. Its safer for the LED to use tin/lead solder (63%/37%), rather than lead free, because the leaded melts at a slightly lower temperature.
However its safer for all of us to use lead free solder. Smile

texaspyro
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Too heck with all those fancy-schmancy hot plates, stoves, and thermometermathingies. I clip the star into the “helping hands” gizmo and use a small butane torch. Never killed an emitter yet.

PyTech
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I never tried soldering without a iron/gun before. Seems a lil tricky.

-Sean

RaceR86
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I tried with a soldier iron the first time.. I have also taken of LEDs with a butane gas light/torch thingy.

If you are only doing 1 or 2, and you have the bare emitter. I can see that some find it easier using an iron and such, but if doing a few, and you are going to take the emitter of an mcpcb and over to a new one.. Its just so fast and simple doing it with a cooking plate. Smile

I once did an experiment with a T6 CW (worthless emitter to me). Used the plate on heat setting 3/4. Re-flow went fine, emitter did light up nicely with a battery. But it did not light up properly with a DMM. Id guess the internal resistance was higher or something. I recently read about another who did a re-flow job and LED was working properly, never got it to work properly (My memory may not me accurate)
I don’t doubt that too much heat can decrease the output, or drastically decrease life time.
Monitoring the heat takes close to zero time. Totally worth it knowing I have been quite gently on the LED IMO. Never had an issue.. Smile

I also find re-flowing on a cooking plate to be quite enjoyable.. Smile

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http://budgetlightforum.com/node/19342

Stereodude
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Crux wrote:
This technique works quite well. Its safer for the LED to use tin/lead solder (63%/37%), rather than lead free, because the leaded melts at a slightly lower temperature.
Leadfree solder is much more troublesome for hand soldering electronics. It’s okay for reflow, but it’s much easier to get a good solder joint when working by hand with leaded solder.

Quote:
However its safer for all of us to use lead free solder. Smile
You routinely eat things you solder? You’ll have to pry my leaded solder out of my cold dead hands.
keltex78
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I haven't reflowed many, but I've had good luck with my process:

I use soldering paste and apply a tiny amount to the contacts on the board, use tweezers to position the emitter in place. I clamp an empty pill on my helping hands, drop the emitter/board onto the pill, then gently heat the pill with a free-standing butane torch. I watch closely, and when I see the emitter settle into place and the solder melt, I remove the heat, then set the emitter on a flat surface to cool as soon as the solder has solidified.

Heating the pill in this way seems to help spread the heat evenly across the board better than heating the board directly, and it's easier to control the heat than when using a hot plate.


Keepin’ the “B” in BLF

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It sounds like the XM LEDs won’t really be suitable for flashlight use. Pity…

Pavithra_uk
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Im also doing same thing. but I use cloth iron.

some shiny surfaces doesn’t give correct temperature readings when using IR thermometer

gadabout
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Hi guys

Very much a newbie wrt soldering emitters so please forgive the following stupid questions Smile

I've read the Cree datasheets several times in the past year or so and seen a number of references to heating and time spent at various temperatures. 

Heating rates, cooling rates, maximum temperatures - it all sounded quite complex.

Does any "home modder" take notice of this stuff or is it pubished as a guide for assembly-line type operations?

I would like to make a triple XP-G2 for a P60 host but doubted my ability to perform the reflow.  I guess it becomes trickier regarding timings when there's 3 emitters to seat? Would it be important to work quickly?

I have rosin-cored solder that I use for small electrical jobs but I'm guessing that is not suitable for this application.  What should I be looking for to do the job properly?

A small amount of solder is needed on the star initially?  Do you apply this with a soldering iron or while the MCPCB is on the hotplate?

How important is it to get the temperature down quickly once the emitters are seated?  Just blowing on it and sitting it on a cool surface is fine?  I don't imagine I'll be doing lots of this stuff initially so won't be doing the next one while the first one cools.

Thanks

RaceR86
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gadabout wrote:

Hi guys

Very much a newbie wrt soldering emitters so please forgive the following stupid questions Smile

I’ve read the Cree datasheets several times in the past year or so and seen a number of references to heating and time spent at various temperatures. 

Heating rates, cooling rates, maximum temperatures – it all sounded quite complex.

Does any “home modder” take notice of this stuff or is it pubished as a guide for assembly-line type operations?

I would like to make a triple XP-G2 for a P60 host but doubted my ability to perform the reflow.  I guess it becomes trickier regarding timings when there’s 3 emitters to seat? Would it be important to work quickly?

I have rosin-cored solder that I use for small electrical jobs but I’m guessing that is not suitable for this application.  What should I be looking for to do the job properly?

A small amount of solder is needed on the star initially?  Do you apply this with a soldering iron or while the MCPCB is on the hotplate?

How important is it to get the temperature down quickly once the emitters are seated?  Just blowing on it and sitting it on a cool surface is fine?  I don’t imagine I’ll be doing lots of this stuff initially so won’t be doing the next one while the first one cools.

Thanks

If you want to be as safe as possible, just do as I did in OP. Use an IR gun. Find the limit where the solder melts.. Try to stay close to it. Dont use too much time. I don’t really use the IR gun much now that Im quite familiar with the plate. But its nice to have.
When done, I just blow gently on it. See that the emitter sits nice and flat and put it down on aluminium plate or something.
You apply soldier when the mcpcb is hot on the plate. If you want, you can do the soldier pads too. Its very easy to apply solder once its hot.
Three emitters should be fairly easy. Make all the soldier points wet, just do one emitter after the other.. They self center quite nicely, it should not take much time to put three into a mcpcb. Just be sure you put all on the correct way. Align them all correctly first (positive and negative poles at the right places), then just pick them up and put them on the mcpcb, one after another.

Any normal soldier should work fine. Thin soldier with less rosin/flux would probably be preferred though.

If you worry about it, try with a “worthless emitter” the first time.

BLF LED database – collaboration spreadsheet and latest news about where to buy LEDs
http://budgetlightforum.com/node/19342

RaceR86
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For those who have issues with getting old emitters out of P60 drop-ins (emitters that have had fujick and similar thermal glue under then.) Put then on the plate.. Crank up the heat to the max.
Once it gets warm enough. The emitter gets loose, take it off (re-flow it later). Let the pill sit longer.. And then some more.. And some more.. Just torture the stuff thats under the mcpcb.
The mcpcb should then be easy to take off with tweezers if you hold the pill down on the plate. I only had to use gentle force at maxium. Some were close to 100% loose.

BLF LED database – collaboration spreadsheet and latest news about where to buy LEDs
http://budgetlightforum.com/node/19342

skyrider1
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keltex78 wrote:

I haven’t reflowed many, but I’ve had good luck with my process:

I use soldering paste and apply a tiny amount to the contacts on the board, use tweezers to position the emitter in place. I clamp an empty pill on my helping hands, drop the emitter/board onto the pill, then gently heat the pill with a free-standing butane torch. I watch closely, and when I see the emitter settle into place and the solder melt, I remove the heat, then set the emitter on a flat surface to cool as soon as the solder has solidified.

Heating the pill in this way seems to help spread the heat evenly across the board better than heating the board directly, and it’s easier to control the heat than when using a hot plate.

Exact way I do it. Just use the pill I will be using for the build and hold everything in pliers while heating with a small butane torch.