Measurements of mechanical coupling of non-curing high performance thermal interface materials

Abstract

For high performance cooling applications, a separable thermal interface material (TIM) is inserted between the CPU lid (electrical component) and heat sink surface to reduce the thermal resistance. Non-curing TIMs, including thermal greases, phase change materials (PCMs), putty-like gap fillers, pads, and dry films are potential classes of TIMs that are used in this application. Materials that have higher effective thermal conductivity, such as filled thermal greases and PCMs tend to have lower interfacial contact resistance. The TIMs also mechanically couple the two interfaces through a weak adhesive bond. Data on the adhesive bonding properties of these materials is needed to predict how the TIM interface will behave when the system is subject to tensile forces during manual separation or dynamic loading induced by shock impulses. A series of controlled tests have been designed and implemented to measure the tensile pull strength of the adhesive bond. The suggested methodology, based on ASTM standards for adhesives, presents one approach for characterizing the adhesive TIM interface that could be readily adapted by others in the industry. These measurements complement in-house thermal testing of these thermal interface materials