Abstract - The isolated base, plastic molded, power semiconductor module assembly has been available for various devices for over twenty years. During this time the power bipolar junction transistor, the BJT, has given way to the Insulated Gate Bipolar Junction Transistor, the IGBT, as the self commutatible device of choice especially for voltage source inverter topologies. As part of the power structure design process, careful consideration should be given to possible power device failure. Obviously every power structure designer strives to remain well within the operating limits of the power device as specified by the IGBT manufacturer. However, there are component failures either of the power switching device or of supporting components that result in one or more IGBT power device failures.