Effects of outlet vent arrangement on air traps in stacked-chip scale package encapsulation

The current paper analyzes the effect of outlet vent arrangements on the air traps and pressure distribution of a stacked-chip scale package (S-CSP) during encapsulation. A three-dimensional model of S-CSP is created using GAMBIT and analyzed using FLUENT code. In the molding process, the epoxy molding compound flow behavior calculated using the Castro-Macosko viscosity model by considering the curing effect, and the volume of fluid technique are applied for flow front tracking. The viscosity model is written in C language and compiled using User-Defined Function in FLUENT code. Three different types of outlet vent arrangement are considered in the analysis, namely, Type A, Type B, and Type C. Type A, which has the minimum outlet vent area, shows the minimum air trap and the highest average pressure distribution. The simulation results of the flow front profiles agree well with previous experimental results.