UV curing polyurethane–acrylate composites as full filling thermal interface materials

Abstract

Ideal thermal interface materials (TIMs) can completely fill the interfaces among components to enhance heat transfer between devices and they have emerged as a major strategy to solve heat dissipation problems. However, some micro-scale voids and cavities existing at a device interface can hardly be adequately filled by externally squeezing in the highly elastic thermal interface material, which badly hinders heat transfer. Therefore, the light curing method is a very good path to obtain pre-filled TIMs, which can adequately fill micro-scale voids and cavities and perfectly replicate textures from the interfaces of components. Herein, a kind of polyurethane acrylate (PUA) resin with UV curability and conformal contact flexibility was chosen as a matrix, and an added photoinitiator was excited by UV irradiation to produce active species to trigger polymerization of the active group in the liquid material, thus curing it. By adding copper nanowires (Cu NWs) to bridge the modified hBN, a three-dimensional (3D) heat transfer network is formed to improve the thermal conductivity of the PUA resin. The thermal conductivity of the hBN@PEI–Cu NWs/PUA composites can reach 1.535 W m⁻¹ K⁻¹ at 20 wt% addition of total fillers. Meanwhile, the composites show excellent electrical insulation and good flexibility, and can be stretched, twisted and knotted arbitrarily when used directly, indicating their strong potential in practical applications.