Numerical simulation on wafer warpage during molding process of WLCSP

As the increasing of the chip integration and adoption of large-size wafers, the warpage problem is more serious in WLCSP. Considering that the die size becomes smaller, a full finite-element model with small die-size is difficult to develop. In this paper, a quarter model and a half general plane deformation (GPD) slice model were developed through finite element method (FEM). Their warpage and stress results were compared. Influences of different material and structural parameters in molding process were investigated finally.