Method for Producing Rare Earth Metal-Based Permanent Magnet Having Copper Plating Film on the Surface Thereof

摘要

[Problems] To provide a method for producing a rare earth metal-based permanent magnet having on the surface thereof a copper plating film by using a novel plating solution for use in a copper electroplating treatment capable of forming a copper plating film having excellent adhesiveness on the surface of a rare earth metal-based permanent magnet. [Means for Resolution] The method for producing a rare earth metal-based permanent magnet having a copper plating film on the surface thereof according to the invention is characterized in that it comprises forming a copper plating film on the surface of a rare earth metal-based permanent magnet by means of a copper electroplating treatment by using a plating solution having its pH adjusted to a range from 9.0 to 11.5 and containing at least the following three components: (1) Cu²⁺ ions, (2) a chelating agent having a chelate stability constant of 10.0 or higher for Cu²⁺ ions, and (3) a chelating agent having a chelate stability constant of 16.0 or higher for Fe³⁺ ions (where, the aforementioned chelate stability constants are confined to conditions of pH 9.0 to 11.5).