Abstract: Three bimodal aluminum particle mixtures, i.e., 2 μm/18 μm, 2 μm/50 μm, and 18 μm/50 μm, were used to reinforce epoxy resin. The thermal conductivity and dielectric properties of filled epoxy resins were investigated as a function of relative content of small particles (Ws) when the total filler content was fixed at 60 %. It showed that the thermal conductivity, thermal diffusivity and dielectric properties of epoxy resins varied with changing the Ws. The smaller the difference between two particles, the smaller the Ws was when the thermal conductivity reached a maximum. The maximum dielectric constant appeared at the W50 μm/W18 μm about 2. However, the Ws had negligible influence on the dielectric loss factors, which was near 0.02.

Key words: epoxy resin, aluminum particle, thermal conductivity, dielectric constant