| 摘要 |
Disclosed is a method of treating an electroless nickel plating bath mainly containing a water-soluble nickel salt, a complexing agent for complexing the nickel salt, and sodium hypophosphite as a reducing agent for reducing the nickel salt, including the steps of:repeatedly regenerating and reusing the electroless nickel plating bath in which a phosphite is accumulated by adding nickel sulfate to the plating bath to produce and precipitate nickel phosphite and separating the nickel phosphite from the plating bath; and adding sulfuric acid or a mixture of sulfuric acid and sodium sulfate to the nickel phosphite separated from the plating bath to convert the nickel phosphite into nickel sulfate and phosphorous acid or NaH2PO3, and recovering the nickel sulfate. According to this method, it is possible to simply, positively and inexpensively separate phosphite ions, without inclusion of any impurity, from an aged electroless plating bath in which phosphite ions are accumulated in a large amount, and to simply recover nickel sulfate from the nickel phosphite thus separated from the plating bath and effectively use the nickel sulfate as a reactive medium for removing a plating bath component or phosphite ions.
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