Poor thermal bonding between custom heatsink and semiconductor device
There is a possibility of poor thermal bonding between custom heatsink and semiconductor device (MOSFET or diode in TO-220 package) under the following scenarios:
- Mounting torque not enough (broken thread or nylon screw).
- Surface deformities/burrs on the heatsink.
Special attention will have to be paid to the fabrication of the custom heatsink to ensure proper threading of holes, use of brass/steel screws with insulating sleeves, and smooth finish of thermal bonding surface.