Experimental and Modeling Investigation of the Temperature Activation of TDDB in Galvanic Isolators Based on Polymeric Dielectrics

We report experimental evidence revealing a nonmonotonic temperature dependence of Time-Dependent Dielectric Breakdown (TDDB) in galvanic isolators based on polymeric dielectrics. In particular, the lifetime of the device under TDDB stress decreases when temperature rises from room temperature to 100°C and then steeply increases above the latter temperature. This effect, which introduces a turnaround in the Arrhenius plot of device lifetime, is explained as a result of two competing processes leading to the strengthening and weakening of polymeric chains in the dielectric material, respectively. The proposed physical picture is further supported by a simple numerical model that allows to investigate the temperature dependence of TDDB in galvanic isolators based on polymeric dielectrics under various working conditions.