Thermal management control without overshoot using combinations of boiling liquids

The authors present experimental results related to the use of mixtures of dielectric liquids to control temperature and overshoot while handling high heat fluxes. The test vehicles were specially designed silicon chips containing a large polysilicon heater/resistor with nine thermal sensing diodes. A variety of pure dielectric liquids (boiling points from 81 degrees C to 110 degrees C) were evaluated. Data has been taken on single pure liquids showing the usual expected substantial overshoot (26 degrees C average) during the incipience of nucleate boiling. Various mixtures (20%-95% of low boiling point; 5%-80% of high boiling point) were then tested with some mixtures showing virtually no overshoot (0 degrees C to 6 degrees C) while still allowing high total heat fluxes greater than 30 W/cm/sup 2/. Conduction losses from the chip to the substrate are quantified computationally. Tests were run with bulk liquid temperatures close to the saturation temperature (10 degrees C below) of the mixtures along with a series of tests with bulk liquid temperature 50 degrees C below the saturation temperature. The amount of overshoot showed a strong sensitivity to the bulk liquid temperature.<
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