Prediction of Instantaneous Dielectric Breakdown Voltage of Filler Dispersed Polymer Composites

Abstract

Composite polymer material containing ceramic filler is often used for an electric power device because it has high thermal conductivity and good electric insulation simultaneously. However, the dielectric breakdown voltage of the composite material tends to be lowered by increasing the volume ratio of the ceramic fillers so as to improve the thermal conductivity. Therefore, understanding of the phenomena of dielectric breakdown in the composite material is important to obtain the knowledge for better material design. In this study, the dielectric breakdown voltage of the filler containing composite polymer material was numerically simulated and the obtained results were compared with the data of the sample containing Boron-Nitride and voids (inevitability included during the sample preparation). Microstructure of the composite material was analyzed by SEM and the obtained two dimensional images were used for the numerical simulation of the dielectric breakdown. The dielectric breakdown phenomena of the composite polymer film were successfully performed, and the propagation phenomena of the breakdown in the film thickness direction was simulated. The results showed that the voids in the composite was the initiation point of the breakdown. From the obtained results, it was indicated that the most influential factor of the dielectric breakdown in the used system was the void ratio in the thickness direction.