Core-shell Cu@Al2O3 fillers for enhancing thermal conductivity and retaining electrical insulation of epoxy composites

Heat accumulation has emerged as a critical issue that affects the performance and reliability of modern electronic devices in their evolving toward miniaturization, high power density and high integration. The application of thermal interface materials (TIMs) as a thermal management strategy is commonly employed to tackle this problem. Herein, we report the development and characterization of highly thermally conductive but electrically insulating Cu@Al 2 O 3 /epoxy composites. Stemming from the excellent thermal conductivity of Cu, the Cu@Al 2 O 3 /epoxy composites exhibit thermal conductivity of 1.32 W/m·K at 10 vol% filler content , which is nearly 7 times higher than that of the epoxy resin . Simultaneously, the Cu@Al 2 O 3 /epoxy composites still retain a high electrical resistivity of 2.3 × 10 13 Ω·cm, which is 6 orders of magnitude greater than that of Cu/epoxy composites without Al 2 O 3 barrier layers, because the dense nanoscale insulating Al 2 O 3 shell effectively inhibits the electron transfer . In addition, the Cu@Al 2 O 3 /epoxy composites possess lower dielectric constant and dielectric loss , and better mechanical properties than those of Cu/epoxy composites.