Thermal contact resistance of cured gel polymeric thermal interface material

This paper reports the experimental results on the contact resistance of curable polymer gel thermal interface materials (TIMs) that have different mechanical properties due to difference in the rheology of the polymers. A semi-analytical model for the prediction of the thermal contact resistance of cured gel TIMs is also introduced in this paper. A novel method of finding the transition from grease type behavior to gel type behavior, which is very important for post reliability stress performance, based on G´ (storage shear modulus) and G´´ (loss shear modulus) measurements is reported. Further, post thermal cycling thermal resistance degradation rate of gel TIMs are related to the ratio of G and G´´. Finally, design guidelines for gel TIMs for use in flip-chip packages comprising heat spreaders are proposed.