High performance ultra-thin vapor chamber by reducing liquid film and enhancing capillary wicking

Ultra-thin vapor chambers (UTVCs) show great potential in cooling compact and high-power electronic devices and improving efficiency for energy systems. However, the two-phase flow heat transfer inside UTVCs remains unclear, particularly for those with steam chamber thicknesses of less than 0.4 mm. In this study, the two-phase flow characteristics inside UTVCs with a steam chamber thickness of 0.2 mm are investigated by conducting visualization experiments. Wettability and capillary wicking tests were also carried out to optimize the wicks. The results show that the composite mesh wick enables optimum heat transfer performance for UTVCs due to enhanced capillary wicking, reduced liquid film in vapor channels, and promoted evaporation and boiling. Then UTVCs at a thickness of 0.35 mm with different wicks are fabricated and tested by water cooling and natural convection heat dissipation experiments. The optimum UTVC exhibits the highest effective thermal conductivity of 12,454 W/mK at a heat input power of 3 W, indicating its powerful advantages for the heat dissipation of electronics in limited space. This study sheds light on the unidentified mechanism of two-phase flow inside extremely thin vapor chambers and guides the future design of high-performance UTVCs for cooling compact power devices.