Chemical and diffusion-controlled curing kinetics of an underfill material

Curing kinetics of an epoxy-based underfill material with applications in flip chip ball grid array (FC-BGA) packages has been studied using differential scanning calorimetry (DSC). Non-isothermal DSC curves were obtained with heating rates ranging from 0.5 to 10 °C/min. Glass transition temperature as a function of fractional conversion was determined using temperature modulated DSC. Based on these experimental data, non-linear regression technique was used to evaluate the curing kinetics by considering both chemical- and diffusion-controlled reaction processes. As a result, it was determined that the curing reaction can be described by an nth order autocatalytic reaction partially controlled by diffusion, although the diffusion effect is relatively weak. The obtained optimized kinetic parameters allow us to predict the reaction behavior under various application conditions.