Optimization of Process Parameters for Molding Simulation of Open Cavity QFN

The transfer molding process is already widely applied in IC packaging since it significantly improves the structure reliability. However, in the molding process, the mold voids and wire exposed have always been around in the encapsulation process, which is a problem that needs further investigation. This study focuses on the mold flow behaviour of an open cavity QFN module with a different open cavity design. In this paper, the computational fluid dynamics simulation with a three-dimensional model was developed to analyse the flow behaviour of Epoxy molding compound, and the parameters that affect the transfer molding situation were studied in the mold flow analysis, including mold temperature, transfer speed, pre-heat time and cavity size. The simulation resulted in a proper understanding of the actual situation and through observing the melt front flow, we could predict the void movement trend and the exact locations and sizes of the voids. The analysis showed that these parameters mentioned above strongly influenced the mold flow and air trap location. The simulation analysis helps select optimal molding parameters and cavity size for the mold void issue on molding process.