Study of flow visualization in stacked-Chip Scale Packages (S-CSP)

The stacked-Chip Scale Package (S-CSP) is a new technology that provides high density of the package. It enables to stack the die in a single package. The S-CSP is widely adopted in portable multi-media products. However, the resin flow through a thin surface and wide filling area is of concern. Therefore, this paper presents a study of flow visualization during encapsulation process in S-CSP. The Navier–Stokes equation has been solved by the finite different method. For non-linear terms, the Kawamura and Kuwahara technique has been adopted in the flow analysis. Pseudo-concentration based on the volume of fluid (VOF) technique was used to track a melt fronts for each time step. The numerical model has been verified by comparing the prediction with the experimental results. The numerical results show good agreement with the experimental results. The prediction also shows that the short shot problem that occurred for the die top clearance is lower than 0.25 mm.