Development and characterization of imidazole derivative cured bisphenol A epoxy materials for flip-chip underfill applications

This paper aims to provide underfill manufacturers and electronic packaging companies with general information about imidazole derivative cured bisphenol A epoxy materials. Four selected imidazole derivatives and one bisphenol A epoxy resin were investigated in this paper. Differential scanning calorimetry (DSC) was used to study the curing kinetics of the prepared formulations and glass transition temperature (T/sub g/) of the cured formulation. A thermo-mechanical analyzer (TMA) was used to investigate the heat flex temperature and coefficient of thermal expansion (CTE). A dynamic-mechanical analyzer (DMA) was used to measure the storage modulus (E') and cross-linking density (/spl rho/) over a temperature range from 25/spl deg/C to 250/spl deg/C of the cured materials. A rheometer was used to investigate the viscosity (/spl eta/) of these formulations. The effects of the curing agent type and concentration on the curing kinetics, T/sub g/, CTE, E', /spl rho/, and /spl eta/ were then investigated. The correlation between CTE (above T/sub g/) and cross-linking density was examined and discussed.