Impact of Bond Wire Lift-Off on the Switching Transients of SiC-MOSFETs – Kelvin-Source Currents as Potential Indicator of Degradation

In typical power electronics applications, semiconductor switches are subject to various stress conditions during operation. Depending on the load, temperature changes occur within the chip, causing thermomechanical stress on the interconnections within the package. One possible failure mechanism induced by cycling loads is bond wire lift-off. In this paper, bond wire lift-off is treated as if the wire were completely removed from the package. Based on this assumption, the study investigates how parasitic components increase and how this affects the switching behaviour of both single and parallel SiC-MOSFETs. To accurately measure the current through the devices an M-Shunt is integrated into the source path as a low-inductive current sensor. Furthermore, the paper introduces the use of the M-Shunt as a sensor for measuring Kelvin-source currents. It examines how the removal of source bond wires affects the transient and steady-state Kelvin-source currents. By means of artificial intelligence, the change in the Kelvin-source currents might be used as a criterion to assess the health condition and remaining lifetime of the SiC-MOSFET.