Thermo-mechanical process emulation and sensitivity analysis of wafer warpage after reconstitution in fan-out packaging

Wafer reconstitution fan-out is a vital process for serving as a buffer to decouple the processing developments between IC fabrication and electronics packaging. By this approach, the IC packaging is then independent from the chip processing. However, such a process brings numerous mechanical loadings during molding and curing phases. In this work, it is desired to examine the key factor of reconstituted wafer warpage by performing solid thermo-mechanical analyses. To have a deeper insight, simplified 2D and detailed 3D finite element analyses have been constructed to mimic the entire Recon process. Detail thermo-mechanical processing steps are then emulated by these finite element models. After model validation, systematic parametric studies are then performed to investigate the controlling factors for dominating the wafer warpage. The simulation results indicated that the thermal expansion coefficients and the Young's modulus of molding compounds could be the dominated factor. By choosing compounds with more desirable above-mentioned mechanical properties, it is expected that a 20 to 30 percentage reduction of warpage can be achieved.