An Online Monitoring Method of Bond Wire Lift-off Unevenness in Multichip SiC MOSFET Power Modules

Monitoring bond wire lift-off unevenness is the basis for high-reliability operation of multichip silicon carbide (SiC) metal oxide semiconductor field effect transistor (mosfet) power modules. The traditional methods of monitoring bond wire lift-off can only monitor the overall number of the bond wire lift-off for one module. In this article, a new method is proposed to monitor the number of the bond wire lift-off for each parallel chip, which breaks through the limitations of traditional methods. A Kelvin source electrode is added in each parallel chip of the module. Under a constant current source, the voltage ratio related to the bond wires is used to monitor the number of bond wire lift-off for the chip. The validity of the proposed method is verified online by experiments based on a buck converter, a half-bridge inverter, and a double pulse test. Experiments show that the number of bond wire lift-off of each chip can be effectively monitored by the voltage ratio. The normal operation of the converter is not disturbed by the proposed method. The proposed method is not affected by the junction temperature and the gate-oxide degradation of SiC mosfet.