I bought a simple aluminum heatsink intended for a TO-220 device, and though the LED should be easily solderable to the heatsink. I was going by the impression that the solder material easily sticks to aluminum, which did not appear to be the case.
What about a copper heatsink? Like a 1mm thick sheet of copper, now I take it the ideal heat transfer method would be to somehow solder the actual LED onto it (keeping the power leads isolated), or continue with the 0.5mm PCB I made, and just glue it onto the copper sheet with a proper thermal adhesive...
And advice on that front?