| abstract |
An object of the present invention is to form a Sn-Ag alloy layer easily and reliably by stabilizing the plating solution and suppressing variations in the composition of the plating layer. A diffusion prevention layer made of Ni or Ni alloy is formed on a substrate made of Cu or Cu alloy, and then an intermediate plating layer made of Cu or Cu alloy is formed on the diffusion prevention layer. On this intermediate plating layer, after performing Su-Ag plating by electroplating using an Sn plating bath containing 0.1 to 5 g / l of Ag particles having a particle size of 5 to 100 nm, reflow treatment is performed. [Selection] Figure 2 |