Heat sink on mosfets: methods
Hello all. I have a P1 based system that drives brushless DC motors. On the typical system the motor runs under low stress and runs for 10 seconds and is off most of the time. I have a case that is high loads and the motor can get stalled and a mosfet can melt the solder. These are 30amp IRF540 type n channel mosfets. 3 are high side 24VDC and 3 are low side. The load is so high that trying to set a current trip threshold above some limit monitored by the P1 via ADS1115 16bit A2D chip doesn’t allow a good headroom to kill the motor because the stress is dynamic and not fixed. What I want to do as a bandaide is add heat sinks. These PCBs have very little copper on top and bottom of the SMT mosfet pads. For a fast PCB update I’m thinking to convert to TH mosfets and add one solid aluminum plane to the high side - as all large pads are 24V on the high. The 3 low side large pads must be separate. What is the most idea what sink in smallest form factor I can stick on the back of vertical mounted mosfets? Thanks.