| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 96 === Applying a Thermal Interface Material (TIM), which has an excellent heat conductivity value, into the interface between the heat source surface and the heat-spreading module could greatly reduce the temperature drop across the interface between the heat source and the heat-spreading module. In order to obtain the optimal choice of TIM, the thermal conductivity of TIM should be determined precisely.
The materials used in this study were thermal pad and thermal grease, and two thermal conductivity measuring methods were compared, including measuring the thermal conductivity value using a steady-state heat transfer equation and a transient state heat transfer equation, respectively. The steady state heat transfer equation is based on a one-dimensional heat conduction principle, wherein the temperature difference across a material becomes constant and the thermal conductivity of this material can be determined using a formula. The measurement of thermal conductivity value using transient-state heat conduction employs a line heat source, whose heat dissipates laterally to the material to be tested. The variation of temperature with time in the heat source was used to derive the thermal conductivity value of the tested material.
The results showed that measuring the thermal conductivity value by the steady-state heat conduction method obviously needed a longer measuring time, but it could obtain more precise results. On the other hand, the precision of the transient-state heat conduction method was less precise because of the possible existence of air bubble next to the thermocouple and the utilization of a simplified equation for fitting the measured data.
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