Sulphur related Corrosion in Power Modules and its Impact on the Switching Performance

Abstract

High power semiconductor modules, exposed to polluted (i.e. H2S) and moist climates can experience corrosion at the packaging materials. Sulphur and copper will form Cu2S-dendrites in the insulation trenches of the substrates, which are able to short the insulation distance. But, previous experiments pointed out, that modules with excessive dendrite growth are able to withstand high blocking voltages under DC-bias. While most IGBTs will operate under switching operation with fast transients, ohmic connections at insulation distances will change the situation tremendously. For this study, 1200 V silicon-IGBT-modules in a standard package were preconditioned in an accelerated corrosive gas test and will be operated in a switching test bench to verify corrosion related performance issues in active operation.