Patent ID: 7402226
Filing Date: 2008-07-22
Classification: C23C,H01F

Abstract:
1. A method of manufacturing a small rare earth permanent magnet comprising the steps of: forming a cylindrical or disc-shaped rare earth magnet with a hole forming an inner surface, wherein the magnet has a surface to volume ratio of 2 mm inserting an electrode wire into the hole of the cylindrical or disc-shaped magnet, supporting the magnet on the electrode wire in a depressurized tank, placing the electrode wire between oppositely-disposed targets in the tank, wherein the oppositely-disposed targets are ring-shaped targets disposed concentrically with respect to the center axis of the cylindrical or disc-shaped magnet, the electrode wire extending and being fixed on a rotation shaft of a motor located outside of one of the ring-shaped targets, reverse-sputtering the magnet while the magnet is made to be electrically negative through the electrode wire, transforming an R metal (R denotes at least one kind of rare earth elements selected from the group consisting of Y, Nd, Dy, Pr, Ho and Tb) or an alloy containing an R metal into fine particles by a sputtering method, rotating the magnet with the electrode wire as a rotation shaft, allowing the fine particles to fly three-dimensionally and deposit to form uniform film onto the whole or part of the surface of the magnet, allowing the film to diffuse and permeate from the surface of the magnet to the inside of the magnet to at least a depth corresponding to a radius of a grain exposed on the outermost surface of the magnet, and thereby modifying the damaged magnet surface so that the magnetic characteristic (BH)