Technical > Electronics > Placing a LED on a substrate

Placing a LED on a substrate

Interesting project. Is that Bergquist substrate metal? You may want to search on "eutectic die attachment" for some hints even though the LED is not an open die. Usually eutectic die attachment is done under vacuum to pull any air bubbles out from under the die. If you're not using reflow at home you might want to use some bottom heat like from a hot plate. A technique I've used is to get the hot plate temperature to just below that needed to liquify the solder and then add just a little heat from a hot air gun or even a soldering iron.
I think eutectic solder (63/37) is used because it solidifies at the the same temperature as it melts, then when the assembly is moved there's less chance of dislodging the die. For home use I would think 60/40 is OK. Make sure there's no flux trapped under the LED because it will impede heat transfer just like an air bubble. If your going to do a lot of these you should consider reflow.

reply to Subaru

reply to hardware bum
I can order some 63/37 it sounds like some nice stuff to have, I was going to use the hot plate technique, in my case I have a gas oven so I can vary the temp in a larger range.

I do have a vacuum pump but I have no idea on how to get the placement I want and heat at the same time.

I opted for the Cree over the rebel because the larger size of the whole mounting base.

So now when you say make sure no flux is trapped under how can I avoid that?
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reply to lutful

reply to Subaru
I'm not sure you can totally avoid trapping flux. Just be careful not to apply too much flux, like a puddle, under the LED. And let the flux burn out as long as you dare. I never meant to suggest that vacuum was a reasonable technique at home unless you're an over the top type. Even then you would spend a lot of time getting it working.

I took another look at the Bergquist data sheet and see the base metal is aluminum and I read the no lead as they are saying their carrier is ROHS compliant, not mandating that you use no lead solder.

reply to Subaru
Hmm I ordered about $30 in things from mouser and not much in a rush I noticed it got upgraded to 3-day.

Also speaking about that reflow station are they just for use for reflow or can they do both? Because I was looking at a adjustable iron and it might be better doing the reflow station instead.

Link to reflow station?

This was just one of them I was looking at last night

»www.amazon.com/Updated-Aoyue-Dig···+station

That can be used to solder new parts.

Ok just wanted to be sure

More here:

»www.circuitspecialists.com/hot-air-station

reply to Subaru
They are Chinese knock offs of Hakko's from what I understand. No idea how good they are.

I was going to buy a Hakko soldering station

ive got a Hakko soldering station and im quite satisfied with it.
the tip can take a beating and still work well.
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I'm so tired of buying all these radio shack irons, I counted the other day and I have 5 of them here... 3 40 watts and the rest 15.

Yeah they suck that's why I plan on getting a better one.