Abstract
The dissolution properties of Cu in molten Sn–Cu–Ni and Sn–Zn alloys were investigated and compared with those of Cu in Sn–Ag–Cu alloys. In the Sn–Cu–Ni alloys with small amounts of Ni, the dissolution rate of Cu decreases with increasing Ni content when the Ni content is below 0.15 mass%. The dissolution rate is proportional to the difference between the saturated solute concentration in liquid (Cs) and the solute concentration in liquid (C), (Cs−C), which is estimated from the isothermal section of the Cu–Sn–Ni ternary phase diagram. In the Sn–Zn alloy, the Cu–Zn reaction layer forms at the solder/Cu interface. The layer prevents Cu dissolution and thus the dissolution rate of Cu is dramatically reduced.
