Rapid increases in the power ratings and continued miniaturization of power electronic semiconductor devices have pushed chip heat fluxes well beyond the range of conventional thermal management techniques. The heat flux of power electronic chips for hybrid electric vehicles is now at the level of 100 to 150W/cm2 and is projected to increase to 500 W/cm2 in next generation vehicles. Such heat fluxes lead to higher and less uniform IGBT chip temperature, significantly degrading the device performance and system reliability. Maintaining the maximum temperature below a specified limit, while isothermalizing the surface of the chip, have become critical issues for thermal management of power electronics. In this work, a hybrid cooling system design, which combines microchannel liquid cooling and thermoelectric solid-state cooling, is proposed for thermal management of a 10mm × 10mm IGBT chip. The microchannel heat sink is used for global cooling of the chip while the embedded thermo-electric cooler is employed for isothermalization of the chip. A detailed package level 3D thermal model is developed to explore the potential application of this concept, with an attention focused on isothermalization and temperature reduction of IGBT chip associated with variations in thermoelectric cooler sizes, thermoelectric materials, cooling system designs, and trench structures in the DBC substrate. It is found that a thin-film superlattice TEC can deliver a superior cooling performance by eliminating more than 90% of the temperature non-uniformity on 100∼200 W/cm2 IGBT chips.

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