Epoxy Composites with Added Aluminum with Binary Particle Size Distribution for Enhanced Dielectric Properties and Thermal Conductivity

Three kinds of hybrid aluminum (Al) particles with binary particle size distribution, i.e., [2 μm/50 μm], [2 μm/18 μm] and [18 μm/50 μm], were added in epoxy (EP) to prepare hybrid Al/EP composites with enhanced dielectric properties and thermal conductivity for embedded capacitor applications. The dielectric permittivity, dissipation factor, and thermal conductivity of three types of hybrid Al/EP composites were investigated as a function of relative volume fraction of smaller-size Al of hybrid Al particles (Vs) at a total filler content of 60 wt.%, respectively. The results indicate that dielectric permittivity and thermal conductivity of the hybrid Al/EP mainly depend on two factors, such as the type of hybrid filler and the Vs. The maximum dielectric permittivity of 48 appears at Vs = V18μm/V(18μm+50μm) = 35%. While, the above two factors have a negligible influence on the dissipation factor, which is as low as 0.022. The highest thermal conductivity of 1.28 W/m K is obtained at Vs = V18μm/V(18μm+50μm) = 50%. The maximum thermal conductivity for three hybrid systems shifts towards lower Vs with decreasing the size ratio of a larger Al to a smaller one.