Embedded Liquid Cooling of High-Power Microelectronics Using Liquid Metal

Liquid metals have high thermal conductivities and shows great potential in liquid cooling of high-power microelectronics. This paper studies embedded liquid cooling using liquid metal (eutectic GaInSn). A thermal test vehicle (TTV) is fabricated for cooling performance analysis. It is deposited with a heater and two resistance temperature detectors (RTDs) for heating and temperature monitoring, and etched with embedded micro-pin fins for cooling enhancement. The TTV is tested with GaInSn and deionized water. Numerical simulations are conducted using ANSYS Fluent and validated with test data. A temperature discrepancy between tests and simulations in the inlet area is found in GaInSn cooling. It is attributed to the poor wetting in the inlet area (near RTD1) due to the large Laplace pressure of GaInSn in the TTV. The finding suggests that in addition to thermal properties, surface tension also needs to be considered when designing and developing liquid metal micro-coolers. Our simulation results show that GaInSn without fins shows better cooling effect compared to deionized water with fins. Besides, for the case of no fins, GaInSn cooling achieves much lower chip temperature, higher heat transfer coefficient with a slightly lower coefficient of performance compared to deionized water. It means that the geometry of liquid metal micro-cooler can be greatly simplified without compromising the cooling performance. Further experimental studies are be conducted for verification.