Prediction of wire sweep during the encapsulation of IC packaging with wire density effect

More wires in a package and smaller wire gaps are the trend in the integrated circuit (IC) packaging industry. The effect of wire density is becoming increasingly apparent, especially on the flow pattern of the epoxy molding compound during the molding process and, hence, on the amount of wire sweep. In most mold flow simulations, the wire density effect is ignored. In order to consider the wire density effect on the predicted amount of wire sweep in the analysis, several indirect approaches were used by researchers before. But those approaches were not general enough to be applied to all cases. This paper presents a more direct and convenient approach to consider wire density effect by including wires in the mesh model for three-dimensional (3D) mold-filling analysis. A thin small outline package (TSOP) with 53 wires is used as the demonstration example, and all the wires are modeled in the 3D mesh. By comparison with experimental results, it is shown that this approach can accurately describe the wire density effect. When the wires are included in the mesh model, the predicted wire sweep results are better than those without considering the wire density effect.