Underfill process for two parallel plates and flip chip packaging

Two parallel plates with a dimension of 5 mm × 5 mm and various gap heights (5, 10, 15, 20, 25, 30, and 35 μm) are simulated using a finite volume method-based software. A three-dimensional model is constructed, and a non-Newtonian underfill flow is simulated using computational fluid dynamics. The flow front advancement is monitored using the volume of fluid model. The underfill process for the two parallel plates and effect of gap height are the main focuses, and the application of flip chip packaging with a gap height of 30 μm is studied. The gap height has a crucial influence on the filling time and pressure drop. The presence of solder bumps is found to have a significant effect on the flow pattern at the melt flow portion. The comparison of the simulation and analytical results are in good conformity for the underfill flow of the two parallel plates.