Qualification of phase change thermal interface material for wave solder heat sink on FCBGA package

This paper reports the outcome of multiple environmental stresses subjected to quantify the thermal impedance value (R/sub js/) of a phase change thermal interface material for wave solder heat sink on a bare die FCBGA package. Based on the accelerated reliability stresses, statistical models were created where possible to represent R/sub js/ performance over time at use condition and temperatures using modifed Arrhenius type of equations. The lack of adequate pressure on the TIM produced significant material degradation in bake. However, the post reliability R/sub js/ derived was still below the thermal design target of 1.96 /spl deg/Ccm/sup 2//W which, indicates that the TIM material can sufficiently cool the package until the end of its use life.