Is solder mask a valid electrical insulator?

There is a copper pour over the entire top of the my PCB, which is part of GND net. It turns out that the surface mounted 1W LEDs I'm going to use have the heat slug connected internally to the LED's +ve terminal. Can I rely on the solder mask to insulate the +ve voltage (~3V ish) from GND? Long term?

December 7, 2023

No, I would not rely on a solder mask as an insulator, because it is very thin and can be nicked easily.

The key issue is going to be how to properly heat sink the LED without a good thermal connection to the heat slug. High-power LEDs usually want the heat slug soldered or thermally epoxied to a heatsink. This can be PCB copper, but since you stated that the PCB copper is connected to the GND net you can’t connect to it.

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

Oliver Smith

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