A uniform temperature, ultra-high heat flux liquid-cooled, power semiconductor package

A heat-exchange process for use in semiconductor heat sinks is described. It involves the use of subcooled nucleate boiling at concave curved surfaces, where radial acceleration can be used to develop significant and beneficial buoyancy forces. This system provides a heat transfer surface with a uniform temperature (the boiling point of the fluid) and requires no vapor-liquid separation process since all vapor bubbles are immediately condensed in the subcooled liquid. Use of low-boiling-point dielectric fluids, e.g. FC72 (BP 56 degrees C), establishes a uniform heat sink temperature that is independent of location or environment and does not require elaborate coolant and/or environmental conditioning. The low junction to fluid specific thermal resistance of approximately 0.1 degrees C/W-cm/sup 2/ and high heat flux dissipation capability approximately 6000 W/cm/sup 2/ inherent in this system lend themselves to a design with high reliability and low manufacturing costs. Failure rates are reduced, and leakage currents are lowered by virtue of lower device operating temperatures.<
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