STRUCTURED POLYDIMETHYLSILOXANE (PDMS) COMPOSITE WITH ENHANCED THERMAL AND RADIATIVE PROPERTIES FOR HEAT DISSIPATION

Heat dissipation plays a vital role in electronic devices, and heat sinks are widely used to dump the heat generated by the devices via convection and conduction, while thermal radiation is usually ignored in conventional heat sinks due to the small temperature difference with the ambient temperature. To take advantage of thermal radiation in heat dissipation applications, this work studies a structured composite made from mixing copper powders into polydimethylsiloxane (PDMS) films as a heat sink material with enhanced radiative properties. Owing to the host material of PDMS, the composite can be formed into various shapes using a wax-mold method at near room temperature. Furthermore, the thermal properties of the composite are enhanced for improving the heat dissipation performance. Thermal property characterization shows 500% enhancement in the thermal conductivity (1.1 W/m K) of PDMS/Cu composite compared to pure PDMS (0.18 W/m K). A tenfold increase in thermal emissivity (0.8) compared to aluminum (0.07, oxidized surface) is exhibited via infrared spectroscopy with an integrating sphere. By comparing steady-state temperatures under the same heating loads in a home-built thermal chamber, the heat dissipation performance is evaluated for plain sheet and structured fin samples made of pure PDMS, PDMS/Cu composites, and aluminum at heating loads up to 1000 W/m(2). Numerical thermal analysis is also conducted to further analyze the contribution from radiation and convection. The positive effects of enhanced thermal emittance and conductivity on heat dissipation are confirmed by the lowest temperatures of PDMS/Cu samples.