Removing heatsink from fets

Does anyone know of a way to unglue a heatsink from fets? I’ve got a rearranged 4.12 that has all the fets on one side and a big heatsink glued to them with silicone heat transfer. The VESC has died (the drv and at least one fet) and I need to remove the heatsink to stand any chance of repair…

On a related topic if anyone can cast an eye over my settings to see why the VESC died I’d be very grateful…

settings on another thread here.

try medical alchohol and try to break free.

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I am not sure that alcohol will do much to the silicone, worth a try though. The best mechanical way would be to hold the PCB that the FETs are soldered onto and the heatsink, and twist them apart. The fets have enough surface area to not rip them off. If you try prying them you will risk ripping the copper off of the PCB.


I’d say use a flat head screwdriver or hobby knife to try and pry the heatsink away from the FET’s. Like @Martinsp said becareful to not put to much stress on the PCB as you might either break the board or separate the copper from the substrate.

Just removed one from a spot welder. Used a sharp knife and carefully took away as much as I could get to and it came off relative easy. It takes some fiddling with the knife tho ^^

Cheers for the input, I’ll try in the morning…

Any ideas on why it died?

I’d try the alcohol mentioned first. It pops hotglue right off, not because it dissolves it but because it seeps in between the glue and whatever it’s on, silicone is a similar bond I’ll bet, might work, might not, won’t hurt.

Twisting it off was the answer… no solvent needed,

Cheers for the input!

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