Comparative study of anhydride and amine-based underfill materials for flip chip applications

Anhydride and amine epoxy systems are widely used as hardeners in underfill materials for flip chip packaging. A comparison was made between these two systems in order to evaluate the comprehensive performance of the resulting underfill. It was found that the addition of multi-size silica particles has little effect on the curing reaction of the epoxy mixture while a significant effect on increasing the viscosity, storage modulus, Tg and lowering the CTE and the magnitude of the tanS peak with the increase of SiO₂ loading for both anhydride and amine curing system. Moreover, with the same filler loading, compared with the amine based underfill, the anhydride system exhibited much lower viscosity, glassy modulus, and CTE in the glassy region and lower Tg thus showing a potential for flip chip underfilling applications.