Predictive Cohesive Zone Modeling for Delamination at PCB-Potting Material Interfaces Under Four-Point Bend Loading With Sustained High-Temperature Exposure

Potting is one of the most effective techniques for safeguarding electronics assembly in challenging harsh conditions, including shock and vibration. Interconnect failures are often preceded by delamination at the PCB and epoxy interface. PCB-Epoxy interfaces have not been extensively researched for interfacial fracture resistance under high thermo-mechanical loading. In this study, bi-material PCB-epoxy samples are made and exposed to long-term high-temperature aging followed by monotonic four-point bend loading. The evolution of the interfacial integrity under sustained high-temperature exposure has been quantified. The study looks at five distinct types of potting materials with varying properties. The specimens are exposed to a high temperature of 100°C and 150°C for 30 days, 60 days, 90 days, 120 days, 180 days, 240 days, and 360 days. Steady-state strain energy release rate, mode-I (KI), and mode-II (KII) stress intensity factors are determined for the PCB-Epoxy interface. Cohesive zone parameters for each of the PCB-Epoxy interfaces have been determined and implemented into a predictive cohesive zone model (CZM). The PCB-Epoxy bi-material specimen has been modeled in ABAQUS with a cohesive zone at the interface and subjected to mode-I four-point bend loading. Damage is considered to occur at the interface where the cohesive zone has been modeled. For both pristine and aged tests, the damage accumulation is predicted using the interfacial fracture parameters from the experiment.