MICROMINIATURE MAGNET EXCELLENT IN ANTICORROSION

摘要

PROBLEM TO BE SOLVED: To prevent deterioration of squareness ratio of a demagnetizing curve after an anticorrosion covering film is coated, in a microminiature Nd-Fe-B based sintered magnet wherein single weight is at most 1 g and the surface is coated. SOLUTION: Electroless plating or vapor plating is adopted as a means for forming a covering film. Quantity of hydrogen contained in magnet base material and the covering film is controlled to be at most 100 ppm. As a result, deterioration of squareness ratio of a demagnetizing curve can be prevented.