A Novel FOWLP Process Emulator for Predicting Time-Dependent Plastic Effects in Multi-Step Accumulated Thermal-Mechanical Asymmetric Warpage

This paper presents a novel viscoelastic process emulator for Fan-out Wafer Level Packaging (FOWLP) that enhances the accuracy of warpage and residual stress predictions. The emulator incorporates the viscoelastic behavior of epoxy mold compounds (EMC) using a hybrid Time-Temperature Superposition (TTS) approach. A step-by-step finite element model that integrates EMC material properties obtained from a three-point bending test and fitted with the Prony series. The proposed TTS hybrid method balances simulation efficiency and accuracy by reducing computation time by 10% while maintaining a minimal warpage error of 0.5% compared to full viscoelastic analysis. Simulation results highlight the importance of accounting for viscoelastic effects, as static models overestimate warpage by 31%. Though the hybrid approach requires further refinement, its preliminary application demonstrates significant potential for efficient and accurate multi-process warpage prediction in FOWLP.