| 摘要 |
PURPOSE:To remove the copper ion contained in a sensitizing solution for electroless plating by preciptating it in the form of copper oxalate, by adding oxalic acid or oxalate to said sensitizing solution. CONSTITUTION:Copper is dissolved in a sensitizing solution for electroless plating comprising an aqueous palladium salt solution and an aqueous stannic salt solution from an object to be treated and the sensitizing activity thereof is lowered by the accumulation of copper ion. In this case, oxalic acid or at least one oxalate such as sodium oxalate or potassium oxalate is added in an amount of 0.1g/l or more. Because the copper ion in the sensitizing solution is precipitated and separated as copper oxalate, the deactivated solution can be again regenerated as the sensitizing solution for electroless plating by removing copper oxalate by filtration. |
