Study of the Mechanism of Liquid-Metal-Assisted Thermal Interface Materials

With the increase in power consumption of integrated circuits, thermal interface materials (TIMs) attract significant attention. Liquid metal (LM) is an emerging high thermal conductive TIM, because of its excellent rheological properties which are helpful to fill micro gaps existing in a thermal interface. However, due to the apparent leakage hazard of pure LM, they are usually mixed with other materials for applications. In this work, the thermal resistance of silicone oil mixed with LM is about five times lower than that of it mixed with AlN powder of the same volume. This is a counterintuitive fact as the intrinsic thermal conductivity of LM is approximate to 20Wm(-1)K(-1), which is more than ten times lower than AlN's thermal conductivity of 260-320Wm(-1)K(-1). In this study, it is suggested that the reason can be attributed to deformed LM and their wetting process on the interface. Moreover, when introducing high load (83 vol%) LM or simultaneously introducing LM and AlN (sum-load 83 vol%) in silicone oil, these composites achieve high thermal conductivity, low thermal resistance, and good compressibility. In practical application, the SO+LM+AlN composites also show much better heat-dissipation ability than commercial thermal grease.