Abstract
As plating time passes, in the acid electroless nickel plating solution containing sodium hypophosphite, phosphite ions are produced and accumulated. When the amount of the ion is increased over a limiting value, nickel phosphite cristalline is formed and suspended in the solution, which cannot be used any more.
The limiting value of accumulation of the phosphite ions under various conditions was investigated from the solubility of nickel phosphite and the amount of sodium citrate added to prolong the life of the solution was also estimated, and the composition of the electroless nickel plating at pH 5.0 was determined. It was found that the life of the electroless plating solution could be estimated through the composition and the pH of the solution.
