| 摘要 |
PURPOSE:To improve an SN ratio and to increase a medium margin by incorporating 0.5-15wt% Mn into a Co-Ni-P alloy film constituting a magnetic recording medium. CONSTITUTION:A nonmagnetic substrate is immersed in an electroless magnetic plating bath consisting of a cobalt sulfate, nickel sulfate, sodium hypophosphite, sodium tartrate, sodium malate, ammonium sulfate, etc., and the Co-Ni-P alloy film is deposited to about 1,000Angstrom thickness on the substrate while the pH and temp. are maintained at prescribed values to provide a magnetic layer. Manganese sulfate is incorporated at 0.5-1.5wt% into the plating bath in this stage to obviate an increase of the max. value of coercive force until the film thickness attains 1,000Angstrom . The magnetic layer which has the large SN ratio and obviates the fluctuation of the coercive force is thus obtd. even if the plating bath is continuously used.
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