LED Heatsink Options

Looking for ideas on sources for heatsinks. I have a bunch of these Cree XR-E's on 16mm sinkpads (entire backside is exposed metal that's isolated from the circuitry) that I've pulled from flashlights that I've upgraded.

I'm going to use them for random lighting fixture projects, so I just run them at 350mA but they still could use a heatsink. Anyone have any ideas for random sources of unconventional chunks of copper or other solderable suitable metal that I could use? I have a variety of aluminum IC heatsinks and whatnot but aluminum doesn't take solder.

Perhaps someone could tell me, if I went to a hardware store and picked up some heavy bolts, is there any particular kind of metal they come in that would take to soldering? Heck maybe just use a roll of pennies and still be cheaper on face value?

Ever heard of aluminum brazing? Durafix, Alumaloy, Alumiweld, etc -- stuff you see in TV commercials. Solder sticks to it.

So what you can do is make a small divot (with a ~1cm drill) in an aluminum heatsink or flat bar, fill it with aluminum braze, sand it flat, then solder the LED directly to it. Pretty straightforward but you need a good torch (or two) when you're dealing with large pieces of aluminum heatsink.

That metal PCB material is aluminum - you can’t solder to it.

I use thermal epoxy (two-part stuff - arctic silver makes an affordable one) and stick them to larger pieces of aluminum, or heatsinks I have kicking around, or even just onto steel beams. Steel is not as good a conductor of heat as aluminum, but it’s usually good enough.

INTP: Anyone have any ideas for random sources of unconventional chunks of copper or other solderable suitable metal that I could use? I have a variety of aluminum IC heatsinks and whatnot but aluminum doesn't take solder.

Perhaps someone could tell me, if I went to a hardware store and picked up some heavy bolts, is there any particular kind of metal they come in that would take to soldering? Heck maybe just use a roll of pennies and still be cheaper on face value?

Why do you want to solder the heatsink. Solder the wires to those oval pads, and glue the LED base(s) to some aluminium strip/case/sheet/heatsink with thermal glue or thermal pads. Leo..

No idea. Just figured it'd be a secure way to secure it. I'll look into thermal epoxy. Is that stuff particular about the metal it adheres?

Or put some thermal grease (the white stuff) between the part and the heatsink.

CrossRoads: Or put some thermal grease (the white stuff) between the part and the heatsink.

Then you also need to secure it mechanically (screws, rivets). Thermal glue or thermal pads does both. Leo..

Well, the PCB is shaped to be screwed down.

Be careful there. There is a circuit board under that white paint. If you do, use nylon screws or plastic washers.

I use screws for the bigger COB LED boards, but these are tiny 1watt LEDs. Leo..

CrossRoads: Well, the PCB is shaped to be screwed down.

Negative. Those are not screw spaces. This, having come from a flashlight, has those spaces for the LED lead wires to go back into the flashlight.

Screws right there would invariably hit the leads/pads.

Well, thermal glue or screws with nylon/plastic insulators then.

No screws. I will not be drilling into whatever metal the heatsink will be made of.