Quote from: mrm0 on June 16, 2013, 09:31:58 AM

Quote from: turtle83 on June 16, 2013, 08:49:01 AM

Quote from: mrm0 on June 16, 2013, 08:18:38 AM

Quote from: turtle83 on June 16, 2013, 04:37:52 AM

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.

Ah makes sense. So, drill small hole in the base of the heatsink, but leave a bigger gap in the fin area such that the screw of the spacer goes thru heatsink base plus pcb, but the weight is is carried by the heatsink. Going to be a little tricky. Or maybe not use the heatsink hole for the spacer, but rather get heatsink bigger than pcb and use the outside area for spacers... decisions...

Another advice : Any issues with using thermal adhesive rather than screws/bolts for mounting pcb on heatsink? <-- cause we are no longer mounting heatsink on pcb, but other way round.