Ah thanks.
M3 is 3mm and M4 is 4mm. They just use the Mx rating for screws. Maybe ill try with both. Its best if the screw attaching the heatsink is as snug as possible...
Nope, stay with M3 screws. For two reasons:
- drilling tolerances
- thermal expansion of the PCB.
Thanks. Any tips for mounting heatsink? Would the PCB take the weight of aliminium heatsink if the pcb is mounting on hex spacers?
Probably it would, but the generic rule is not to use PCBs as mechanical carriers. I would mechanically attach heatsink(s) to the frame/enclosure and have PCBs mounted to heatsinks. So the heatsinks would support PCBs rather than the other way round. Or, if you want to use hex spacers as stands, use them to directly support the heatsink as well, i.e. use only the inner set of holes.