Role of silica nanoparticle in multi‐component epoxy composites for electrical insulation with high thermal conductivity

Multicomponent epoxy micro/nano‐composites containing micro‐alumina, micro‐quartz, and nano‐silica were fabricated to develop electrical insulation materials with high thermal conductivity. Simply changing the ratio between the alumina and quartz microparticles caused a trade‐off relationship between the thermal conductivity and electrical insulation. Increasing the alumina content in the epoxy‐alumina/quartz micro‐composites enhanced the thermal conductivity but deteriorated the dielectric strength. An increase in the thermal conductivity without incurring a loss in the dielectric strength was achieved by incorporating silica nanoparticles in the epoxy micro‐composites. Adding silica nanoparticles to the epoxy micro‐composites was found to be more efficient in improving the thermal conductivity compared to increasing the alumina ratio, especially at low alumina/quartz ratios. This behavior corresponded to theoretical models. Therefore, we provide a useful insight, both practical and theoretical, into the more advanced optimization of designing multicomponent epoxy composites for electrical insulation with high thermal conductivity.