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Abstract

A method of circulating an electroless nickel plating solution is characterized in that the system comprises the following process steps effected in the following order: (A) a step of electrolessly plating nickel using a plating solution having nickel hypophosphite contained as a chief chemical material for supplying a plating metal ion Ni.sup.2+ and a hypophosphorous acid ion H.sub.2 PO.sub.2.sup.- acting as a reducing agent; (B) a step of removing HPO.sub.3.sup.2- from a plating solution that has aged in the step (A); (C) a step of desalting the mother liquor separated from the step (B); and (D) a step of adjusting the components of the treated plating solution and then circulating same back into the step (A) of electroless nickel plating. According to the present invention, the plating solution is free from the formation and accumulation of a sulfuric acid salt and hence a long service life is ensured and a great advantage in environmental protection is provided.

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First Claim