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

Abstract

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 (V _s) 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 V _s. The maximum dielectric permittivity of 48 appears at V _s = V _18μm/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 V _s = V _18μm/V _{(18μm+50μm)} = 50%. The maximum thermal conductivity for three hybrid systems shifts towards lower V _s with decreasing the size ratio of a larger Al to a smaller one.