| 摘要 |
PURPOSE:To use a brass layer as a buffer zone and to prevent the concentration of stress due to the thermal expansion between a substrate and a substrate layer and between the substrate and a magnetic layer by providing an electroless brass plated layer on the nonmagnetic metallic substrate, forming the nonmagnetic substrate layer on the plated layer, and furnishing a magnetic layer on the substrate layer. CONSTITUTION:A brass layer 2 is provided in 0.01-30mu film thickness on a nonmagnetic metallic substrate 1 of Al or an Al alloy, Mg or an Mg alloy, etc. by electroless plating. A nonmagnetic substrate layer 3 consisting of metals such as Ni, Cr, Mo, etc. or an alloy of the metals and P, B, etc. is formed on the layer 2. A magnetic layer 6 consisting of a Co-Ni alloy, gamma-ferrite, etc. is further furnished on the layer 3. A protective layer 5 is provided on the layer 6. Since the linear expansion coefficient of the brass layer 2 lies between respective linear expansion coefficients of the substrate 1 and the nonmagnetic substrate layer 3, the concentration of stress due to the thermal expansion is not generated between the substrate 1 and the substrate layer 3. Accordingly, the magnetic layer 6 on the substrate layer 3 is formed uniformly and densely. Consequently, the positioning of the record on a disk is carried out accurately.
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