Monitoring of ageing chips of semiconductor power modules using eddy current sensor

The relevance of the eddy current sensing technique to monitor the ageing state of electronic power modules has been experimentally studied. To do so, a commercial eddy current sensor was implemented for the evaluation of COOLMOS^TM transistor chips soldered on a direct copper bonded ceramic substrate of a power module. The measurement data obtained over a large frequency bandwidth were analysed in the normalised complex impedance plane. The analysis shows that the sensor enables the chip and the substrate to be separately sensed. Furthermore, the ageing state of artificially aged chips can be clearly monitored. These preliminary results allow the design of eddy current micro-sensors dedicated to power module in-service monitoring purposes to be envisaged.