Thermal conductivity and electrical conductivity of silicone rubber filled with aluminum nitride and aluminum powder

Abstract The effects of aluminum nitride (AlN) and aluminum powder (Al) on thermal conductivity and electrical conductivity of silicone rubber compounds were investigated and it was found that the thermal conductivity increased with increased fillers content. Silicone rubber filled with Al powder of 45 μm over 50 phr, exhibits higher thermal conductivity as compared to that filled with AlN powder of 4 μm at the same filler content. The results indicate that the particle size effect played a significant role on thermal conductivity. In addition, it was found that electrical conductivity and thermal conductivity increased proportionally when the Al powder content increased. In contrast, only the thermal conductivity kept increasing proportionally, but the electrical conductivity almost remained unchanged for the rubber with AlN. Furthermore, a new type of silicone rubber compound with a combination of the two fillers, comprising 100 phr of AlN powder and 50 phr of Al powder, was developed, which lead to synergistic enhancement of the thermal conductivity. The improvement in thermal stability of the new type of silicone rubber compounds enables use in high temperature environments.