Prediction of mechanical stresses induced by flip-chip underfill encapsulants during cure

A constitutive model is presented for predicting the stresses in thermosetting resins during and after cure. An overview is given of the experimental techniques used for estimating the parameters in this model. The model is validated by comparing its predictions to a second set of measurements that has not been used for the actual parameter estimation. This validation shows that the model is capable of giving fair predictions of the measured stresses. The model is implemented in a commercially available finite element package and its use is demonstrated by applying it to the study of a flip-chip underfilling process.