Investigation of the Moisture- Driven Dynamics of Time- Dependent Dielectric Breakdown in Polymeric Dielectrics for Galvanic Isolators

We present an investigation that relates the dynamics of Time-Dependent Dielectric Breakdown (TDDB) in polymeric dielectrics for galvanic isolators to the moisture content of the materials. The analysis is based on experimental data for the temperature activation of both TDDB and moisture absorptionloutdiffusion in the devices. The observed phenomenology is explained through a solid physical picture, which is quantitatively supported by a simple-yet-effective model for the moisture-driven dynamics of TDDB. Results point out primary aspects to consider when assessing the reliability of galvanic isolators based on polymeric dielectrics under real on-field operating conditions.