Public evidence metadata · SEM-EVIDENCE-0011

Gold Embrittlement of Solder Joints

This expanded paper draws on solder-joint investigations performed over more than 20 years. It examines eutectic tin-lead, SN62, Sn-Ag, and SAC305 joints using BSE SEM imaging, EDS, image analysis, fracture-surface examination, plating cross-sections, and mass-balance calculations. The paper treats approximately 3 wt% gold as a useful screening value while showing why average gold concentration alone can be misleading. Case evidence includes localized Au-Sn segregation below the calculated joint average, agreement and disagreement between chemistry and image area, Cu- and Ni-bearing reaction products in lead-free systems, an extreme SAC305 transformation, thin die-attach damage during cool-down, anomalous connector plating, thermal-aging effects, and low-gold comparison cases.