A Finite Element-Based Method for Cohesive Zone Model Parameter Extraction in 2.5D Packaging Interfaces

Interfacial reliability in 2.5D packaging is critical, particularly for the PI/Si interface in the redistribution layer (RDL). To support early-stage analysis before conducting complex experiments, this work develops a simulation-based inverse extraction method for Cohesive Zone Model (CZM) parameters using finite element modeling in ABAQUS. A simplified model is established based on existing Cu/PI interface studies, and the effects of cohesive strength, elastic modulus, and interface size on failure behavior are investigated. Results show that lower PI modulus leads to nonlinear rising behavior in the displacement–load (D–L) curve, possibly due to elastic deformation and moment effects. Additionally, the peak load is found to depend on both the maximum cohesive strength and fracture energy. This numerical study provides insights into the sensitivity of D–L responses to key CZM parameters, offering theoretical guidance for subsequent experimental design and parameter calibration in 2.5D interface reliability research.