Thermo-Mechanical Simulation Framework for Assessing Process-Induced Delamination Risks in Large-Area Fan-Out Panel-Level Packaging

Abstract

Abstract. This study develops a finite element modeling (FEM) framework for predicting interfacial fracture behavior during the debonding stage of fan-out panel-level packaging (FOPLP). Although FOPLP offers advantages such as mechanical robustness, high throughput, and cost efficiency, it is susceptible to residual stresses and interfacial delamination, particularly during debonding. To address these reliability concerns, a multiscale FEM approach integrating global and detailed submodels was established to resolve localized stress fields, with an emphasis on regions surrounding critical copper pillars. Simulation results indicate that stress concentrations are most severe at the SiNx–under bump metallurgy (UBM) interface. Parametric studies show that increasing the chamfer radius at UBM corners significantly reduces stress peaks, improving reliability. Furthermore, reducing interfacial fracture toughness within the debonding layer was found to reduce stress in the UBM region, suggesting process-level mitigation strategies. Larger UBM etching angles were found to reduce stress in SiNx and UBM layers. The influence of process-induced residual stresses, including those from chemical shrinkage and thermal mismatch, was systematically evaluated. Critical stress values and temperatures at potential failure sites were identified, providing insight into delamination mechanisms. By incorporating experimental observations and simulation techniques such as the virtual crack closure technique (VCCT), the proposed framework enables accurate prediction of interfacial failure and global warpage in FOPLP assemblies.