Three-dimensional modeling of mold filling in microelectronics encapsulation process

In this paper, a fully three-dimensional (3-D) numerical model is developed to simulate the mold-filling behavior in the plastic encapsulation of microelectronics. The conventional Hele-Shaw approximation is inadequate to analyze such a complex process owing to the 3-D nature inherent in the molding compound flow between leadframe and mold cavity. The developed methodology combines the efficiency of SIMPLE-based finite volume method (FVM) and the robustness of VOF volume-tracking method to solve the two-phase flow field in complex mold geometry. An efficient method for automatic generation of prismatic mesh for plastic packages is also presented. The molding process of a TSOP II 54L LOC package is studied. Short-shot experiments are conducted to investigate the filling patterns at several different flow times. The close agreements between experimental data and simulated results demonstrate the applicability of the present computational model for practical plastic encapsulation simulations.