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I want to create my own light source using high power 1W LEDs. Can I solder high power 1W LEDS on aluminum with 60/40 solder?

Here's a picture of a potential heatsink

Napster
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  • Why not use thermal adhesive? – Phil Frost Jan 12 '15 at 00:00
  • Unusual. Possible. Risky. Special solders exist. Special fluxes exist. If you put lots of solder on the surface with the LED NOT present, heat the teal to soldering temperature and then abrade the metal under the solder blob then with effort you can often get it to "wet" well enough to then solder too. Doing it some other way is liable to cause less hassles. – Russell McMahon Jan 12 '15 at 01:38

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In short, no. Aluminum needs a special kind of solder because it doesn't tin like many other metals with normal solder. Aluminum oxide forms very fast when aluminum is exposed to oxygen, and aluminum oxide doesn't stick to normal solders.

Aluminum solder melts at such a high temperature, that you'll probably burn your LEDs out before you ever attach the LEDs to the heat-sink.

As Phil states, it's better to use a thermal adhesive or use a thermal paste and then mechanically clamp the items together.

horta
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  • How can I mechanically clump LEDs? – Napster Jan 12 '15 at 03:30
  • @ConradC I'm not say clamping is practical for small things such as LEDs. I was thinking more for processor heat sinks. Those are clamped by screws with springs on them. I don't know what your led's look like, but if they already have a base attached to them, you could possible drill holes in the heat sink, and tap the holes to make threads for screws to fit in that then can clamp down on the LED bases. I'd still go with a thermal adhesive though. It'd be a lot simpler and easier. – horta Jan 12 '15 at 16:36
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Regardless of the other answers here, I found it easy to solder to Aluminum with the right flux. This works great for me. I tried a bunch of different solders and all worked. 40/60 included. If there is any anodization or other coating on the heat sink, you'll have to sand it off, or otherwise remove it. And of course you'll need a lot of heat to get the heat sink hot.

George Herold
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  • It is extremely likely that that flux is corrosive and would cause damage to the soldered items if not cleaned off completely after use. This may be "rather hard" to do well. Experience or suitable testing would tell. – Russell McMahon Jan 12 '15 at 01:36
  • @RussellMcMahon, Yeah I cleaned with warm soapy water, and a tooth brush. I had a piece of copper bus wire soldered to aluminum foil on my bench for several months... no signs of corrosion. I tin the Al bits, clean, and then solder the copper on. – George Herold Jan 12 '15 at 01:40