| Abstract Scope |
We report numerous combinations of solders and plated metals on components and circuit boards. A common finding is that the growth of diffusion compounds, at the solder-to-plating interface, is a precursor indicator of solder connection interfacial failure. The precursor is associated with vacancy accumulation and observation of Kirkendall voiding. Diffusion between plating and precipitation compounds leads to connection separation. Vacancy content accumulates into area voids as the diffusion compounds grow. The diffusion compounds occur concurrent with, or subsequent to, the precipitation compounds. The diffusion compounds are stoichiometrically richer in the plated metal than are the precipitation compounds. We show cross-sectional microstructures, and compound chemistry identifications, from the following solder-to-plating systems: tin-lead-to-gold, tin-lead-to-copper, indium-lead-to-gold, gold-germanium-to-nickel, tin-lead-to-iron-nickel, tin-lead-to-palladium, and lead-free solder connections to copper and iron-nickel.
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