Internal degradation monitoring of power devices during power cycling test

A technique to monitor internal degradation to failure of power devices in real time was proposed. Required components for this technique are (1) non-destructive inside imaging, (2) power stress control and (3) device cooling. We constructed the system with scanning acoustic tomography (SAT), DC power supply controlled by own made program and water cooling system, respectively. In the case of a TO-3P packaged MOSFET, propagation of internal degradations to failure was successfully recorded as time series data by using this system. At the present time, the system is modified for high power and large size IGBT modules.