Power Transistor Heat Sink Design Trade-offs

T. Eppes, I. Milanovic, and G. Quarshie
University of Hartford
West Hartford, CT

Power transistors require heat sinks to dissipate thermal energy and keep junction temperatures below the recommended limit. The reliability and longevity of any semiconductor device is inversely proportional to the junction temperature. Hence, a significant increase in reliability and component life can be achieved by a small reduction in operating temperature.

A range of heat sink designs and mounting procedures are available, each with reasonably predictable performance. However, it is easy to overdesign by incorporating a margin of safety that is too high. This paper describes the results obtained by modeling the heat transfer process in several heat sink designs and implementations.