Liquid Metal Embedded Elastomers (LMEE) as Low-BLT Thermal Interface Materials

Extended Abstract SUMMARY Achieving reliable thermal interfaces with low bondline thickness (BLT) is a difficult challenge in the thermal management industry. Mismatched coefficients of thermal expansion between the substrate, die and heat spreader lead to warpages during thermal cycling which the thermal interface material (TIM) must survive. Common failure mechanisms of the TIM during thermal cycling are i) when the warpage exceeds linear and nonlinear maximum strain capacity of the TIM leading to tearing or ii) when the interfacial stress between the TIM and die/IHS exceeds the maximum adhesion stress leading to delamination. To combat this issue, in this study, we sought to develop a TIM that can achieve high strain at break and high adhesion, while maintaining low thermal resistance. Our formulation, based upon the liquid metal embedded elastomers (LMEE) architecture, combines polymers with a high volume fraction loading of liquid metal inclusions. While the TIM presented in this manuscript needs to undergo further reliability testing before being deployed in-package, it represents a step toward breaking the fundamental limitations imposed by conventional materials.