Fluid flow and heat transfer characteristics of liquid cooling microchannels in LTCC multilayered packaging substrate

The fluid flow and heat transfer of liquid cooling microchannels embedded in low temperature co-fired ceramic (LTCC) multilayered electronic packaging substrate have been investigated. Four cooling systems were supplied for high power application of 100 W LED lamp, including aluminum finned heat sink and LTCC substrates with parallel, serpentine and spiral microchannels. The pressure, flow rate, Reynolds number, fiction factor, Poiseuille number and Nusselt number were experimentally measured and theoretically analyzed. The heat transfer behaviors characterized by the drop of maximum working temperature and temperature distribution were measured by a thermal video system based on infrared thermometry. The microstructure and roughness of microchannel were studied by using Scanning Electron Microscope and Tribo Indenter. The measured flow rate of parallel microchannel under the same inlet pressure was much higher than those of serpentine and spiral microchannels. A linear dependence of Nusselt number on Reynolds number was observed and conformed to the convective heat transfer mechanism in microchannel. The parallel microchannel was found to have the best heat transfer performance and reduced the maximum working temperature to 99.52 °C, much lower than those of other cooling systems. The temperature distribution of LED lamp was also significantly improved by the internal parallel liquid cooling microchannel in LTCC substrate.