Anti-leakage and recyclable phase change thermal conductive films with ultralow thermal impedance enabled by Field’s metal via the generation and internalization of metal oxides

The heat dissipation performance of a thermal interface material (TIM) is greatly dependent on its total thermal impedance, which can be effectively reduced by introducing a solid–liquid phase change material (PCM). However, previously reported phase change TIMs (PCTIMs) have been developed only based on organic PCMs with low thermal conductivities; thus, they cannot achieve low thermal impedance. Herein, Field’s metal (FM), which is a metal phase change material with a melting point of approximately 60 ℃, is first employed to develop a novel PCTIM with an ultralow thermal impedance. Trace oxidation is conducted on FM, and Bi2O3 and SnO are thus generated, followed by forming nanoscale particles by internalization. The formation of the nanoscale metal oxides increases the surface free energy and interfacial interaction force, thereby increasing the viscosity and improving the film-forming ability of the oxidized FM. The phase change thermal conductive films with different thicknesses, which are fabricated from the optimal oxidized FM, exhibit little liquid leakage, even at a pressure of 200 psi, and reach an ultralow thermal impedance of 0.03 cm2·K·W−1 at a thickness of 100 μm after the solid–liquid phase change, which is lower than those of the previously reported PCTIMs. The optimal film possesses good thermal reliability and recyclability, and shows a significantly better cooling effect than a commercial PCTIM with an identical thickness. These ideal characteristics make the FM-based phase change thermal conductive films up-and-coming in practical applications.