High Fidelity Reliability Prediction of SAC Solder Under Drop Impact via High Strain Rate and Temperature Dependent Properties

초록

In this study, high strain-rate properties of Sn-3.0Ag-0.5Cu (SAC305) solder and printed circuit board (PCB) materials were experimentally characterized at room temperature using Split Hopkinson Pressure Bar (SHPB) tests. Dog bone-shaped specimens were fabricated for both materials using SHPB tensile tests at strain-rate range of 600-1500 /s to obtain dynamic stress-strain responses. The Johnson–Cook constitutive model was employed to describe the mechanical behavior of the solder, whereas a rate-dependent plasticity model was used to characterize the mechanical response of the PCB. Drop failure life was predicted using the SED extracted from critical solder joints within a Darveaux model. To validate the predicted drop failure life, board-level drop tests were conducted in accordance with JEDEC JESD22-B111 using ball grid array (BGA) assemblies mounted on PCBs. The FEM simulations incorporating SHPB-based high strain-rate properties predicted the drop failure life within 8 % of the experiment results. These results demonstrate that SHPB-based high strain-rate characterization of both solder and PCB is essential for accurate board-level drop failure life prediction. The proposed approach establishes an experimental-FEM correlation between high strain-rate material behavior and solder joint drop reliability.

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