Enhanced thermal conductivity and electrical insulation properties of liquid crystalline epoxy composites by using optimized alumina hybrid fillers

In order to satisfy the increasing demand for packaging materials of power devices, a contradiction between thermal conductivity and breakdown strength urgently needs to be addressed. In this work, we reported a novel liquid crystalline epoxy composites with a hybrid filler of nano-diamond and modified alumina (AO∗@ND) by self-assembly polymerization of cationic monomer, electrostatic adsorption and a calcination technique. The thermal conductivity and dielectric breakdown strength of the composite with biphenyl liquid crystalline epoxy and 10 wt% AO∗@ND (500 °C-6 h) were 0.99 W/m·K and 75.2 kV/mm, respectively, which achieve a remarkably synergistic enhancement compared to those (0.2 W/m·K, 69.64 kV/mm) of the commercial bisphenol A epoxy for packaging materials of power devices. The mechanism for the simultaneous increase was indicated by the simulation calculations and experimental results. This research could provide a novel insight for the development of high-performance epoxy composite materials for the encapsulation of new-generation power devices.