Addressing Warpage Issue and Reliability Challenge of Fan-out Wafer-Level Packaging (FOWLP)

In this paper, we present the design and fabrication of a mold-1st FOWLP that seeks to solve potential warpage and reliability issues. We examined three different mold-1st FOWLP options that are designed and developed for this work. We have created viscoelastic constitutive models and parameters for both the dielectric materials and epoxy molding compounds (EMCs) which have been used for the design of FOWLP. Measurement of the volumetric cure shrinkage of EMCs has been done using a newly developed method. Advanced modelling capability on wafer warpage has been successfully established after full material characterization and the predicted wafer warpage results are verified with experimental results. Based on advanced modeling results, new design metrics for FOWLP process flow useful for the packaging industry have been developed. Calibrated micro-stress sensors, that were designed and fabricated internally, are used monitor stress during the FOWLP process. The experimental stress measurements have been used to validate the predictions of the advanced stress model. Finally, board level solder joint reliability has been designed, simulated and enhanced leading to the establishment of a successful life prediction model for FOWLP that will prove useful to the packaging industry.