Covalently bonded silica interfacial layer for simultaneously improving thermal and dielectric performance of copper/epoxy composite

Copper/epoxy (Cu/epoxy) composite is a kind of important thermal management material due to its high thermal conductivity, excellent mechanical robustness and low cost. However, susceptibility of Cu to oxygen and high electric leakage loss of Cu urgently require a protective interfacial layer with anti-oxidation and electric insulation properties. Currently, the reported interfacial layers for Cu fillers either are prepared under harsh condition or possess inferior insulation/thermal resistant properties. Here, we propose a strategy to prepare dense silica interfacial layer containing Si-NH-Si/Si-H reactive groups for Cu/epoxy composite, which not only protects Cu from oxidation but also tethers Cu and epoxy with covalent bonds. Compared with Cu/epoxy composite, the as-prepared Cu@silica/epoxy composite exhibits enhanced thermal conductivity, high temperature stability without decrease of thermal conductivity at 150 °C for 200 h, and improved dielectric performance with dielectric permittivity and loss of 13.1 and 0.1 at 100 Hz, respectively. This work provides an efficient approach to covalently bond interfacial layer for simultaneously improving thermal and dielectric property of Cu/epoxy composite, showing high potential for real application.