AC–DC electric field-induced microstructure arrangement in SiCw/SE composites for enhanced electro-thermal performance

Advanced power modules are evolving toward higher operation voltage and miniaturization, imposing stringent challenges on the electro-thermal co-optimization of packaging materials. However, conventional doping strategies are constrained by the orientation and spatial distribution of fillers, making it difficult to simultaneously achieve high thermal conductivity and excellent electrical insulation. Precisely regulating filler orientation and spatial distribution to maximize electro-thermal synergy remains a critical challenge. This study proposes a synergistic AC-DC combined electric field induction strategy to achieve precise control over filler orientation and targeted enrichment. The AC electric field drives the electrorotation and attraction of SiC whiskers (SiCw), allowing precise orientation to maximize their nonlinear electrical conductivity and thermal conduction properties. Meanwhile, the DC electric field induces the electrophoretic migration of SiCw toward regions of high electric and thermal field concentration, enabling device-level targeted optimization. Experimental results demonstrate that this strategy enhances the thermal conductivity of SiCw/silicone elastomer (SE) composites by 333 % (reaching 0.65 W/(m·K)) while maintaining excellent thermal stability. Additionally, the nonlinear electrical conductivity coefficient is tunable within the range of 0.9 to 4.9, and the switch-field strength is reduced to 1.07 kV/mm, showing superior electric field responsiveness. Further simulations and experiments reveal that the composite reduces peak electric field stress by 32.5 % and increases the partial discharge inception voltage (PDIV) by 54.4 %, significantly enhancing the insulation reliability of power modules. This breakthrough in electro-thermal performance optimization marks a significant advancement in the electrical insulation and thermal protection of high-voltage power modules.