| 摘要 |
PROBLEM TO BE SOLVED: To obtain an electroless plating method for tin or tin alloy by which solder wettability by the minimum plating thickness is secured when the electroless tin plating and electroless tin alloy plating, for instance, electroless solder plating are continuously executed. SOLUTION: A minimum set plating thickness for securing the solder wettability, which increases in accordance with an increase in the concentration of copper ions in a plating liquid, is set and the minimum set plating thickness [μm] is determined from an equation of [K×copper ion concentration [g/L]+R], and the values K and R are kept to be within the range of 0.3<=K[μm.L/g]<=0.6, and 3.5<=R[μm]<=5 respectively.
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