Optimization of heat transfer of microchannels in LTCC substrate with via holes and liquid metal

In recent years, with the advances in integrated circuit and electronic chips, as well as the development of MEMS technology, the total power density of the system increases. Therefore, requirements for high performance cooling methods become more urgent. As water being the working fluid, microchannels have been integrated into the LTCC substrate, which has applied to the thermal management of the heat flux of 1 ~ 4W/cm². But it still cannot meet the conditions of high heat density. In this article, two methods are used to improve the thermal performance of the substrate, with a kind of low-melting point metal alloy (GaIn₂₀) as the working fluid in the channels (with 400μm in width) and adding via holes in the area of microchannels. And by means of three-dimensional numerical simulation, Reynolds numbers, flow rate and the maximum temperature of substrate on heat transfer performance of LTCC substrate are simulated with software COMSOL Multi-physics. The cooling performance of the LTCC substrate with microchannels was experimentally measured under different flow rate of deionized water when heat flow density of the heating modules is 1w/cm² and 2w/cm². While comparing to the simulation of heat transfer performance under the same circumstances, relative error of the maximum temperature do not exceed 8%. Simulation results show that the module is to be effective. With the low-melting liquid metal alloys GaIn₂₀ and deionized water that used as the working fluid respectively, heat transfer performance was simulated. Comparatively analyze both thermal performance under similar dynamic conditions with heat resource different heat flux, the results show that when the heat flux increases to 5W / cm², the cooling performance of deionized water as the fluid is not ideal, but the low-melting metal is able to cool the maximum temperature of the substrate to 354K with GaIn₂₀ flowing at a rate of 70ml/min when the heat the fluid density increases up to 10W / cm². While adding via holes to the substrate, the maximum temperature is able to be reduced to 357K below with GaIn₂₀ flowing at flow rate of 70ml/min when the heat flux density increases up to 30W / cm².