Abstract
The influence of Cu and Ni additions on the morphology of the intermetallic compounds (IMC) formed at the interface of the liquid Sn-Cu solder and the Cu substrate has been studied. At low Cu concentrations only a thin IMC layer is formed which remains almost unchanged in time and the substrate is dissolving quickly. Ni additions significantly accelerate the growth kinetics of the IMC layer, prevent the formation of a Cu₃Sn layer and reduce the rate of substrate dissolution.

Key words
lead-free solders, intermetallic layer formation, Sn-Cu alloys, Cu substrate

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