So I've got this thermal interface material, which is a grey sheet of gooy stuff, a bit thinner than a millimeter. I've always suspected that this is not the best material that I could get.
Now I made a test: my LED PCB screwed onto a long flat aluminum bar.
Without thermal interface material: LEDs slowly rise up to 96°C (measured with a thermographic camera).
I let it cool down, then with thermal interface material: LED rise up to 114°C.
I mean, WTF, why is this stuff worse then nothing?
When both surfaces are straight and relatively flat (I have no idea how I could quantify the imperfections), is it best practice to use no interface?
Or are there better interfaces? Which?
Or is thermal paste still the only good option? (I don't like liquid stuff on my electronics...)
Regarding electrical conductivity: All traces on the bottom of the PCB are fully covered with solder mask, they are at 5V and the aluminum is connected to ground.
@lenaschimmel you can buy thermally conducting pads that are comparable to thermal paste these days, ppl use them in computers
