Comprehensive Investigation of Die Shift in Compression Molding Process for 12 Inch Fan-Out Wafer Level Packaging

Die shift is a critical issue in compression molding process for fan-out wafer level packaging (FOWLP). A comprehensive investigation has been performed using the developed multi-step simulation scheme to capture the die shift variation during the process. Several experimental tests were performed on 12 inch wafer to validate the simulation results. Both the thermal-mechanical (TM) effect and the mold compound fluid flow (FF) effect are considered in the multi-physics simulation model. The expansion and contraction varies along with 5 major steps in the compression molding process. The influences of materials, dimensions and process on the die shift caused by TM and FF effect are analyzed and compared. Two shift compensation methodologies, constant and dynamic pre-shift, have been conducted and evaluated for performance improvement. By optimizing multiple factors, the maximum die shift of +/- 5 mu m has been achieved based on the multi-steps simulation analysis. The results and conclusions obtained are expected to aid the molding process of FOWLP.