Dynamic HV-H³TRB Test on 3.3 kV SiC MOSFET Modules

In standard environmental reliability tests, Silicon Carbide (SiC) MOSFETs show a superior performance compared to their Silicon counterparts. This raises the question if the SiC modules are robust and reliable under all circumstances in the field and against all failure mechanisms or only in the standard laboratory tests. The HV-H³TRB (High Voltage – High Humidity High Temperature Reverse Bias) test is the standard test for humidity reliability and SiC modules survive this test for several thousand hours, easily surpassing the 1,000 h qualification requirement. However, in field service the devices are exposed to steep voltage slopes (high dv/dt) instead of the DC voltage stress applied in a standard HV-H³TRB. In this work, a dynamic HV-H³TRB test was performed on 3.3 kV SiC MOSFET modules for more than 4,000 h with switched high voltages of 80% V nom , only observing minor degradations and reversible blocking capabilities.