Numerical study of preventing flow-induced die-shift in the compression molding for embedded wafer level packaging

This paper presents a new numerical model to characterize the compression molding of wafer level packaging with epoxy polymer molding compound. With its successful application on a reconfigured carrier wafer with fully populated 3-die packages embedded, flow pattern in the wafer level compression molding is characterized for various process conditions and 2 different molding compounds. Focuses have been given on die shift induced by the impact of compression mold flow. Flow pattern and flow drag on individual die is presented. If the adhesive force is less than the maximum flow drag on the die during compression molding, die shift will take place. Results show that the peripheral dies experience highest flow drag and thus are more likely to shift outwards. Moreover, higher compression speed at low molding temperature for a low viscosity molding compound increases the risk of die shift. Key advantage of this numerical study is to give the insights into process parameters and provide initial process window to prevent die shift induced by compression flow drag.