This work presents a demonstration of a coefficient of thermal expansion (CTE) matched, high heat flux vapor chamber directly integrated onto the backside of a direct bond copper (DBC) substrate to improve heat spreading and reduce thermal resistance of power electronics modules. Typical vapor chambers are designed to operate at heat fluxes > 25 W/cm~2 with overall thermal resistances < 0.20 °C/W. Due to the rising demands for increased thermal performance in high power electronics modules, this vapor chamber has been designed as a passive, drop-in replacement for a standard heat spreader. In order to operate with device heat fluxes >500 W/cm~2 while maintaining low thermal resistance, a planar vapor chamber is positioned onto the backside of the power substrate, which incorporates a specially designed wick directly beneath the active heat dissipating components to balance liquid return and vapor mass flow. In addition to the high heat flux capability, the vapor chamber is designed to be CTE matched to reduce thermally induced stresses. Modeling results showed effective thermal conductivities of up to 950 W/m-K, which is 5 times better than standard copper-molybdenum (CuMo) heat spreaders. Experimental results show a 43°C reduction in device temperature compared to a standard solid CuMo heat spreader at a heat flux of 520 W/cm~2.
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机译：这项工作展示了一个热膨胀系数（CTE）匹配的高热通量蒸汽室的演示，该室直接集成到直接键合铜（DBC）基板的背面，以改善散热并降低电力电子模块的热阻。典型的蒸汽室设计为在> 25 W / cm〜2的热通量下运行，且总热阻<0.20°C / W。由于对提高大功率电子模块的热性能的要求不断提高，该蒸汽室已被设计为标准散热器的无源，直接插入式替代产品。为了在大于500 W / cm〜2的设备热通量下运行并保持较低的热阻，在电源基板的背面放置了一个平面蒸气室，该蒸气室在有源散热组件的正下方集成了专门设计的灯芯，以平衡液体回流和蒸气质量流量。除了具有高的热通量能力外，蒸汽室还设计为CTE匹配的，以减少热感应应力。建模结果表明，有效导热率高达950 W / m-K，比标准的铜钼（CuMo）散热器好5倍。实验结果表明，与标准固态CuMo散热器相比，在520 W / cm〜2的热通量下，器件温度降低了43°C。
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