SDG #326 A copper core PCB with tiny 1.4mm Luxeon Rubix LEDs

This project episode tackles two things at once: working with a genuine copper core metal PCB, and hand assembling Luxeon Rubix LEDs, which at roughly 1.4mm square are small enough to make placement and reflow genuinely awkward.

The interesting engineering question here is thermal. Standard FR4 is a poor conductor, so high current LEDs run hot and lose efficiency and lifespan. Aluminium core boards are the usual budget answer, but copper offers noticeably better heat spreading, at higher cost and with different fabrication constraints. The video walks through what a metal core board order actually looks like from a prototype house, including the single layer copper limitation, the dielectric layer between the trace copper and the base metal, and why that thin insulating layer matters for both electrical isolation and heat flow.

Assembly is the part most viewers will learn from. A copper substrate sucks heat away aggressively, so hotplate and hot air reflow behave differently from ordinary FR4: ramp times stretch out, and small parts can end up under reflowed if you judge by the usual visual cues. Placing parts this small also means solder paste volume and pad geometry become the limiting factors rather than tweezer skill.

Testing covers current handling, brightness at drive levels the Rubix parts are rated for, and thermal camera checks to see how effectively the copper core moves heat off the die attach area. That comparison is the practical takeaway: if you are designing compact high power lighting, the substrate choice, not the LED datasheet, often decides how hard you can actually push the part.