Anomalous increase of leakage current in epoxy moulding compounds under wet conditions

An interdigitated capacitor embedded in the EMC has been realized and characterized under controlled humidity conditions by applying a DC step voltage and monitoring the leakage current as a function of time. Both experimental characterization and TCAD simulations of dry and wet EMC samples have been carried out to fully understand the involved charge transport mechanisms. The anomalous increase of current with time in wet conditions is explained assuming a build-up of space charge directly induced by the high-injection at the metal electrodes. The assumption is confirmed by TCAD simulations.