DSC and DMTA studies of a thermal interface material for packaging high speed microprocessors

Thermophysical properties and cure behavior of a thermal interface material used in microelectronic packaging have been studied using DSC, DMTA and other thermal analysis techniques. Based on isothermal DSC results, the activation energy for the curing reaction is estimated to be 129 kJ/mol. When heated from −100 to 150 °C, the cured material exhibits a single endothermic peak near −45 °C, which corresponds to the melting of silicone oils in the sample. On cooling, the cured material crystallizes, but shows various degrees of undercooling depending on the cooling rate. Upon crystallization, DMTA analysis revealed that the storage modulus of the cured material increases dramatically, from several MPa to a few GPa. In the same process, the ultimate elongation decreases by almost a factor of 10. The impact of such static and dynamic mechanical behavior on packaging reliability will be addressed. The influence of curing on the mechanical modulus was also evaluated by DMTA. In addition, coefficient of thermal expansion (CTE) and thermal stability of this material will be discussed.