Liquid Metal Embedded Elastomers (LMEEs) as TIM1 with Highly Reliable & Extremely Low Thermal Resistance Performance

Abstract

Thermal management issues in the semiconductor industry are driven by a sharp increase in power densities, and have created ever-growing concerns over the last decade. To resolve this concern, many attempts are being investigated in device packaging to extract the heat generated away and maintain the functionality of the device. Inside the package thermal interface materials (TIM1) play an important role in transferring the heat efficiently. Design of an optimum material for TIM1 has been an ongoing challenge due to problems associated with interfacial contact thermal resistance, optimized distribution of TIM over the die surface, pump-out and delamination. To accommodate some of these concerns, we introduce a TIM that has liquid metal embedded in elastomeric matrix (LMEE). This material has stretchable and adhesive properties to accommodate large deformation in the semiconductor packages and has shown superior reliability performance. To address these growing thermal challenges, I will highlight performance of LMEEs as a TIM1 by making packaged microprocessors (TTV) and measuring Junction-to-Case thermal resistance (Rjc) at T0 and after HAST, Thermal Shock, Bake and reflow (5x) reliability tests. We show that Liquid Metal Embedded Elastomers (LMEE) material architecture for TIM1 can achieve Rjc < 7 C.mm2/W and maintain this thermal performance under reliability tests. Our current efforts are involved in formulating polymers with enhanced rheological and mechanical properties to demonstrate thermal performances approaching that of liquid metals.