Thermal Characterizations of Solid Thermal Interface Materials

Solid thermal interface materials are often used in thermal reliability tests of IC packages to minimize contact thermal resistance without contaminating the test environment. In this paper, thermal characterizations of solid thermal interface materials, including indium, graphite, and fiberglass were conducted. A TIM tester was utilized to measure the specific thermal resistances across the different STIM materials under a range of compression pressures. While indium exhibited the lowest thermal resistances and excellent thermal performance, graphite materials GA03 and GB01 provided fairly good thermal performance second to the indium material. Considering their lower cost, graphite materials can be good candidates for package testing in place of expensive indium materials at the low-power test range. One-dimensional analysis of the individual thermal resistances, including the bulk thermal resistance, the contact resistance, and the adhesive layer resistance, reveals that the contact resistance is a key element for graphite-based materials, which amounts to around a half of the overall interfacial thermal resistance under operating compression.