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

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
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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.