Cosmic Ray Failures of Power Modules - The Diode Makes the Difference

More than 20 years ago, the phenomenon of cosmic ray induced failures in power electronic devices was first reported [1]. High energy particles can generate 'single event burnout' (SEB) failures in power devices in blocking mode, i.e., the device loses its blocking capability without any precursor on a very short time scale. While the root cause of the failure can rarely be identified after an explosion of the inverter, the statistical probability of cosmic ray failures can be determined from experiment, so that this random failure rate can be well predicted for power electronic systems. The great impact of device architecture will be demonstrated by experimental results for freewheeling diodes, showing that the CAL diode is very robust regarding cosmic ray failures.