Measurement of interfacial thermal resistance of silicone based grease in wide temperature range by laser flash method
Soo Yeol Jeong and Yeon Suk Choi
Thermal grease is widely used as a method of enhancing thermal conductivity by mixing polymer and high conductivity materials such as alumina and copper powder. In this case, the polymer undergoes deformation due to crystallization, thermosetting, thermoplastic, glass transition depending on the temperature. Therefore, when used in extreme environments, the physical properties and state changes should be investigated. In this paper, the thermal resistance of the thermal grease is measured in-situ from –90°C to end of thermally stable temperature. Materials are prepared by mixing polydimethylsiloxane and aluminum oxide, which is the most representative thermal grease. The silicone grease is prepared with a sandwich structure between two copper for the measurements. The laser flash method is used to determine the thermal conductivity of silicone grease using three layers model. As a whole temperature range, the decrease in thermal conductivity of thermal grease is explained by the breakage of the polymer chain and the increase in distance between the filler materials due to thermal expansion. As a result, the total thermal resistance, which increases with ascending temperature, is influenced by the thermal conductivity of silicone grease. On the other hand, the effect of temperature-dependent changes in thermal contact resistance appears to be insignificant.
Keywords: silicone grease, thermal conductivity, thermal resistance, thermal contact resistance, thermal interface material