PROCESS FOR PRODUCTION OF RARE EARTH PERMANENT MAGNETS HAVING COPPER PLATING FILMS ON THE SURFACES

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A process for the production of rare earth permanent magnets having copper plating films on the surfaces by using a novel copper electroplating solution which can form copper plating films on the surfaces of rare earth permanent magnets with excellent close adhesion to the surfaces. The process is characterized by forming a copper plating film on the surface of a rare earth permanent magnet by copper electroplating with a plating solution whose pH is adjusted to 9.0 to 11.5 and which contains (1) Cu2+ ions, (2) an organic phosphoric acid having two or more phosphorus atoms and/or a salt thereof, (3) gluconic acid and/or a salt thereof, (4) a sulfuric acid salt and/or a nitric acid salt, and (5) at least one organic acid selected from among oxalic acid, tartaric acid, citric acid, malonic acid, and malic acid and/or a salt thereof (with the proviso that copper salts are excepted from the components (2) to (5)).