Models for Reliability Prediction of Fine-Pitch BGAs and CSPs in Shock and Drop-Impact

摘要

Drop-induced failures are most dominant in portable electronic products. In this study, explicit finite element models have been used to predict the transient dynamic behavior of various area-array package architectures assembled to printed circuit boards after drop-impact. Parameters predicted include field-quantities and their derivatives including displacement and strain. Methodologies for modeling components using smeared property formulations have been investigated. Reduced integration element formulations examined include-shell and solid elements. Model predictions have been validated with experimental data. Results show that models with smeared properties can predict transient-dynamic response of board assemblies in drop-impact, fairly accurately. A high-speed data acquisition system has been used to capture in-situ strain, continuity, and acceleration data in excess of 1 million samples per second. Ultra high-speed video at 40 000 fps has been used to capture the deformation kinematics. Component types examined include-plastic ball-grid arrays (BGAs), tape-array BGA, quad-flat no-lead packages (QFN), and conduction-cooled ball-grid arrays (C2BGA). Model predictions have been correlated with experimental data. Impact of experimental error sources on model correlation with experiments has also been investigated.