Reverse bias second breakdown in power switching transistors

The second breakdown characteristics under reverse base drive have been investigated for two n-p-n power switching transistor structures using a non-destructive testing circuit. Three types of second breakdown have been identified, all occurring in a single device under different operating conditions. Primary mechanisms, neither of which involve a critical temperature, have been proposed for two of the types. The third type has not previously been reported, nor has a mechanism been proposed. The experimental evidence at this time excludes adiabatic heating as a principal cause of second breakdown in the test devices.