The Phenomenon of Tunnel Structure Mold Flowability Experiment Result and Simulation Study

According as high density packaging options such as multidie staking or tunnel staking technologies are developed, the die staking and tunnel staking of transfer molding process is already widely applied in IC packaging since it significantly improves the encapsulation reliability. However, in the molding process, the mold voids and un-fill issue have always been around in the encapsulation process, which is a problem that needs further investigation. This study aims to investigate the application of mold flow analysis in chip tunnel stacking designs, focusing on key aspects such as mold flow analysis, chip stacking, encapsulation phenomenon, and tunnel geometry. In this paper, the computational fluid dynamics simulation with a three-dimensional model was developed to analyze the flow behavior of epoxy molding compound (EMC), and the parameters that affect the transfer molding situation were studied in the mold flow analysis, including tunnel width, die thickness, die enhance length and the tunnel hydraulic diameter.The simulation resulted in a proper understanding of the actual situation and through observing the melt front flow under the tunnel structure, we could predict the void movement trend and the exact locations and sizes of the voids. The study highlights the importance of mold flow analysis in the design and optimization of chip tunnel stacking. By combining advanced mold flow analysis techniques with the proper selection of tunnel geometry to avoid the mold void or un-fill issue on the tunnel structure.