A Normal-Looking Plated Finish Can Still Fracture at Its Intermetallic Boundary

What the evidence preview establishes

The joints fractured brittlely at the electroplated nickel/Ni-Sn intermetallic interface. Plating construction and intermetallic thickness appeared generally normal, so the evidence did not distinguish high-rate overstress from a less-visible interfacial weakness.

Why this case matters

Clean pad separation does not automatically identify black pad or defective plating. Confirm finish construction, measure the intermetallic, and preserve uncertainty when the interface is abnormal but its initiating stress is unknown.