On-line solder layer degradation measurement for SiC-MOSFET modules under accelerated power cycling condition

In order to distinguish die-attach solder layer and bond wire degradation during power cycling tests, a simultaneous on-line measurement method is proposed in this paper. To measure accurately solder layer voltage drop, the intrinsic diode is used as heating source in place of the MOSFET switch. In this way, the measurement method becomes intrinsically insensitive to possible threshold voltage shifts, typical of accelerated test of SiC power MOSFETs. Finally, the experimental results are presented to verify the feasibility of the proposed test method. It is revealed that the solder layer resistance increases linearly with the number of cycles in good approximation.