Effects of Rheological Properties on the Thermal Resistance of Gel Thermal Interface Materials

Thermal conductive gels are an important class of thermal interface materials (TIMs) as they are shape-adaptive and can fit uneven interfaces and achieve ideal interfacial heat transfer. Low thermal resistance is the key to achieving high heat dissipation efficiency. Most studies only focused on how to enhance the thermal conductivity of the gel TIMs, but ignored the thermal resistance of gels in practical application, which is significantly influenced by the rheological properties of gels. In this work, we have prepared gel TIMs with different rheological properties, and investigated the relationship between the thermal resistance and the rheological properties of gels. The results indicate there is a transition behavior from grease type to gel type with the change of gel modulus, which is composed of storage modulus (G') and loss modulus (G''). The actual thermal resistance of gels is influenced by the gel modulus and the external load, and a semi-analytical model for the prediction of the thermal resistance of gels is introduced in this paper. Further, the reliability performance tests show the thermal resistance degradation rate of gel TIMs is related to the G'/ G'' and good reliability of gels is achieved only when the value of G'/ G'' is greater than 2. This work is a good reference for formulation optimization and performance prediction and gel TIMs.