Abstract: The permanent magnet member 10 for a voice coil motor (VCM) in accordance with the present invention comprises a magnet body 1 including a shorter periphery 11, a longer periphery 12 located at a position separated from the shorter periphery 11 by a predetermined distance, and a pair of side peripheries 13, 14 connecting the shorter periphery 11 and longer periphery 12 to each other, the magnet body having a fan-shaped planar form; and a corrosion-resistant film (Ni plating film 2) applied to a surface of the magnet body. The permanent magnet member 10 has a thickness whose maximum and minimum values yield a difference of 10 to 150 ?m therebetween.

Abstract: The permanent magnet member 10 for a voice coil motor (VCM) in accordance with the present invention comprises a magnet body 1 including a shorter periphery 11, a longer periphery 12 located at a position separated from the shorter periphery 11 by a predetermined distance, and a pair of side peripheries 13, 14 connecting the shorter periphery 11 and longer periphery 12 to each other, the magnet body having a fan-shaped planar form; and a corrosion-resistant film (Ni plating film 2) applied to a surface of the magnet body. The permanent magnet member 10 has a thickness whose maximum and minimum values yield a difference of 10 to 150 ?m therebetween.

Abstract: A magnet body 1 including a shorter periphery 11, a longer periphery 12 located at a position separated from the shorter periphery 11 by a predetermined distance, and a pair of side peripheries 13, 14 connecting the shorter periphery 11 and longer periphery 12 to each other, the magnet body having a fan-shaped planar form; and a corrosion-resistant film (Ni plating film 2) applied to a surface of the magnet body. The permanent magnet member 10 has a thickness whose maximum and minimum values yield a difference of 10 to 150 ?m therebetween.

Abstract: Provided are a method of manufacturing a rare-earth magnet with superior corrosion resistance, and a plating bath used for the method. A first protective film including nickel and a second protective film including nickel and sulfur are laminated in order on a magnet body including a rare-earth element. The first protective film is formed through electroplating with a first plating bath including a nickel source, a conductive salt and a pH stabilizer, and having a concentration of the nickel source of 0.3 mol/l to 0.7 mol/l on a nickel atom basis and a conductivity of 80 mS/cm or over. Thereby, a rare-earth-rich phase can be prevented from being leached out, and the production of pinholes can be reduced. Therefore, the corrosion resistance of the rare-earth magnet can be improved.

Abstract: The permanent magnet member 10 for a voice coil motor (VCM) in accordance with the present invention comprises a magnet body 1 including a shorter periphery 11, a longer periphery 12 located at a position separated from the shorter periphery 11 by a predetermined distance, and a pair of side peripheries 13, 14 connecting the shorter periphery 11 and longer periphery 12 to each other, the magnet body having a fan-shaped planar form; and a corrosion-resistant film (Ni plating film 2) applied to a surface of the magnet body. The permanent magnet member 10 has a thickness whose maximum and minimum values yield a difference of 10 to 150 ?m therebetween.

Abstract: Provided are a method of manufacturing a rare-earth magnet with superior corrosion resistance, and a plating bath used for the method. A first protective film including nickel and a second protective film including nickel and sulfur are laminated in order on a magnet body including a rare-earth element. The first protective film is formed through electroplating with a first plating bath including a nickel source, a conductive salt and a pH stabilizer, and having a concentration of the nickel source of 0.3 mol/l to 0.7 mol/l on a nickel atom basis and a conductivity of 80 mS/cm or over. Thereby, a rare-earth-rich phase can be prevented from being leached out, and the production of pinholes can be reduced. Therefore, the corrosion resistance of the rare-earth magnet can be improved.