An avionics integrity mechanical analysis

In silicon power transistor applications, thermal cycling of the transistor may activate a failure mechanism called thermal fatigue. This phenomenon is caused by the mechanical stresses set up by the differential in the thermal expansions of the various materials used in the assembly of the transistor and heat sink. Thermal fatigue often results in cracking of the silicon pellet or fatigue of the silicon mounting interface. The author considers the avionics integrity process along with an example of a mechanical analysis using the avionics integrity approach. The example involves the determination of the stress-strain relationships found in power transistors and an experimental approach for determining cycles to failure