Enhanced Thermal Conductive Boron Nitride/ Silicon Carbide/ Silicone Elastomer with Nonlinear Conductive Characteristic and Partial Discharge Resistance

Abstract

Wide bandgap power electronic devices with higher breakdown voltages, faster switching, and lower switching losses than silicon-based power devices will be widely used in high-temperature and high-voltage applications. Corresponding packaging materials are urgently required to have higher thermal conductivity and satisfactory insulating properties in wide bandgap power electronic modules. This study introduces a silicone elastomer (rubber) with micron and nano-sized boron nitride (BN) and silicon carbide (SiC) particles to improve thermal conductivity and partial discharge resistance. The thermal conductivity, polarization and depolarization current, and partial discharge were measured to investigate the effect of mixed micro-nanoparticles on thermal and electrical properties. Experimental results show that the composite material has a higher thermal conductivity than the original silicone elastomer. The conductive current of the composite expresses nonlinearity with the increase of load level. Regarding the trap density distribution, the composite's trap depth is generally reduced. The shallow trap density increases, whereas the deep trap density decreases with ascending load level. The partial discharge inception voltage of the composite is higher than the original silicone elastomer, and it increases as the load level rises, which may be explained by the local electric field decrease resulting from trapped charge diffusion around the high voltage electrode. The multiphase BN/ SiC/ silicone elastomer with proper load level has a higher thermal conductivity and better partial discharge resistance, indicating its advantages as packaging material to ease thermal and electrical stress in wide bandgap power electronic modules.