Simultaneous thermal/flow characterization of thermal interface materials

Thermal interface materials used for dissipation of heat in electronic assemblies are often exposed to working conditions that may change the mechanical as well as thermal behavior over time due to both intrinsic change as well as environmental influence. Currently, among thermal interface material solutions, particle filled greases are common. For these materials, the relation between observable change in its mechanical behavior and degradation of thermal performance is not well understood. This may be attributed to challenges associated with characterization of thermal resistance while the sample is subjected to cyclic thermal and/or mechanical loading. An important goal of the present work is to study the change in flow behavior and its effect on thermal performance of the thermal interface material under varying environmental conditions. Squeeze flow characterization is carried out on a custom built tester while simultaneously measuring thermal resistance. The change in flow behavior and the consequent change in thermal performance is tracked using a custom-built tester. The tester enables simultaneous measurements under a single setup. For different material sets, this relation may be different and so a quick characterization technique as the one proposed is desired. Test cases for commercially available particle filled thermal greases are presented where the Non-Newtonian flow behavior and thermal properties are obtained using the proposed technique.