Humidity Testing Of Sic Power Mosfets

Humidity and outdoor application are a challenge for Silicon (Si) and Silicon Carbide (SiC) applications. This paper investigates the effect of humidity on SiC power MOSFET modules in a real application where no acceleration factors such as pressure or high temperature are applied. Since SiC devices can operate at higher temperature than Si, the high-temperature acceleration factor may be obsolete. Moreover, the humidity might be more critical when the temperature inside the converter enclosure and modules housing is varying with daily temperature variations and weather constraints in harsh environments. The breakdown voltages of the humidity-exposed modules are monitored regularly over a extended period of time in order to detect any increase of leakage current which indicates humidityinduced degradation. After 630 hours, the modules operated outdoor presented an increased leakage current at 1.2 kV and over the whole range of applied voltage.