湿-热耦合条件下 PBGA 器件湿气扩散行为仿真研究

Non-hermetic structures like plastic encapsulation in electronic devices are sensitive to environmental moisture. Moisture-induced property changes and stresses critically impact reliability. This study combined hygrothermal aging tests with molecular dynamics simulations to investigate dynamic moisture diffusion within plastic ball grid array(PBGA) packaging. Moisture diffusion parameters under varying conditions were fitted to calibrate the concentration-dependent diffusion coefficient. Implementing this dynamic model in hygro-thermal coupling simulations significantly improved prediction accuracy. Results reveal both Fickian and non-Fickian diffusion modes, with the diffusion coefficient decreasing nearly linearly as average moisture concentration increases. The optimized coupling equations outperform conventional constant-coefficient models in predicting internal moisture distribution. The proposed fitting model and simulation methodology offer a novel approach for predicting the behavior of plastic-encapsulated devices in humid environments, holding practical implications for reliability assessments concerning the storage, interconnection, and long-term operation of electronic devices.