One way to make a Copper Star for a LED - with photos

I have been trying out the other paste I linked to in the first post and I like it so far. Low melt and seems to be pretty clean. I have only used it a couple times. I plan on doing a little “copper star assembly line” when I get some leds in, then I will have more experience with it.

Edit: The solder it paste from Lowe’s was not the best. I ended up squeezing out some on a cardboard and mixing it up well before using it. It seemed to work better. I also tried the “copper solder it” from Lowe’s. I threw that stuff away. Don’t need more high melt stuff.

That looks really great! You could also use clear coat to insulate the contacts.. thats what the manufacturers do.^^

I like your creativity.. if they offer thicker copper plates, you could make the whole heatsink direct to copper.

I like the way u think. good ol yankee ingenuity. u’ve given me a few ideas for future projects. i’m kinda surprised that tape provides enough mechanical connection for the wiring pads. let me know how u center the led.

Once again, you impress. I’ve been wondering lately how to use a 1/2” copper cap to make a pill and you light the way. A bit of 1/2” inside to add mass and a bit outside 1-2mm longer than the cap for driver recess and follow the recipe above. Scratch lines in the first layer might help with keep the pad stable.

This suggests there is more gains to be had from reducing led temperature, as i had assumed they reached their lumen output ceiling due to saturation or some non heat related reason. I wonder if some kind of active cooling, say a peltier cooler, or fan connected to the heatsink behind the led would make a significant difference.

O-L, you hit another one out of the park.

It’s amazing what you can do, running on nothing but 140-proof stubborn:stuck_out_tongue:

Thanks also for the DIY.

To me, it’s just like a processor for a PC. Cooling is the key. Water (or nitrogen) cool a LED and the sky is the limit. Well at least we don’t know the limit for sure until that is done.

Lets hope whoever tries it has fire gear at the ready

Couple of points:

- Test was performed exactly as all of my emitter tests - which is mounted to a 1lb piece of copper barstock imbedded in a 25lb block of aluminum.

- Heat is the key. The cooler an led can be kept, the more power it can be fed to produce more light.

- I have @ 10 150w peltier coolers at work that I could stack together to get an led close to cryogenic...but other than academic interest a test like that wouldn't have much bearing on what could be done in relation to a flashlight.

The results from that test are here. For Justin's benifit, I sent him a graph depicting all three tests.

I agree, you can’t easily put a peltier cooler into a flashlight, so i guess its more of an academic interest. I assume at some point the wires and junctions in the led will fry from the voltage and current if you keep the temp low enough for that to happen.
We could always start a betting pool to see what amperage and lumens a U2 XM-L can take before non heat related failure :wink:

This is the DIY in the proper meaning, of the words!


Thanks everyone, for the kind words and thanks to Match once again, for doing the testing.

I plan on using copper stars like this, in my builds this winter.

I centered these just by setting the led on the pads by eye. Then I hit each outer pad with a solder gun just long enough to heat the low melt solder and last is to heat under the center pad, until it’s solder melts. If the solder is done very thin, it works pretty good.

thanks. Looks like the only main difference between OL Cu star and direct copper mount is at very high amps (>4.5A), so within the realms of sane use OL’s method should be equivalent and a smidge easier :slight_smile:

I was looking up kapton tape and found a document on off gassing from the adhesive here
I don’t know if it’s relavant or not. It seems to relate to condensation of the gasses on switch contacts but I thought it might also affect reflectors adversely. Do people use kapton often on stars without problems? If so then ignore this post. This is a great idea, just want to avoid later disappointment. Thanks

I’ve done something similar, I made my own copper star by sanding a penny until it was flat. Copper is surprisingly expensive material and one convenient thing about the penny is before 1982 they were pretty much solid copper. You’re actually getting more than 1 cent worth of copper for every penny so there is no cheaper way to make a copper star than by sanding a penny flat.

Instead of soldering a base to raise the center you can actually just use the solder itself to bridge the thin gap between the kapton gasket and star. Instead of using copper sheet as conductor you can use copper foil. This way there is minimum thickness between the conductors/gasket and the star allowing the solder to fill the gap in completely. That makes it only one solder joint from the led thermal pad to the star. Solder joints are a big bottleneck for heat conduction so you want to keep them to a minimum.

The Polyminide tape I am using is supposed to have a Teflon Silicon adhesive, not Acrylic. Probably still has off gassing as any adhesive probably would. I imagine even the Silicone domes on leds have some form of off gassing, however minor it may be.

Not trying to be a party pooper and the article did look old. I have not used kapton and don’t know what changes have been made in the adhesive. The article just made me think of the effect super glue can have on domes and lenses. As Gilda Radner said,“never mind”.

Nice work!!