Thermal deformation measurements and predictions of MAP–BGA electronic packages

The thermally-induced deformations of MAP–BGA (matrix array package–ball grid array) packages are investigated experimentally, numerically and theoretically. In the experiments two full-field optical methods: Moiré and Twyman–Green interferometries are employed for the in-plane displacement measurements on the edge and center surfaces of the specimen and the out-of-plane displacement measurements on the top surface of the specimen, respectively. The thermal deformations under various temperature loads are recorded during the heating history. The 3-D linear finite element model is used to validate the experimental observations. A simple beam deflection theory is also newly proposed for prediction of the deformations. The results from the experiments are presented and compared in detail with those from the 3-D linear finite element and theoretical analysis. The good agreements in the experimental and modeling results reveal the validation of experimental data in mechanics sense and the effectiveness of the numerical and theoretical models in physics predictions. It is also observed and verified that the compliance of die attach material above its Tg (glass transition temperature) give more than 25% warpage reduction of that without taking into account Tg effect at high temperature. As a result, neglecting this effect in the modeling will significantly influence the solder ball reliability prediction.