| 摘要 |
PURPOSE:To improve the squareness ratio among the magnetic characteristics and the SN ratio among the recording and reproducing characteristics by combining a plated magnetic film having small coercive force and a favorable squareness ratio with a plated magnetic film having physical properties desirable for a magnetic storage body. CONSTITUTION:A plated film of 100Angstrom thickness is formed on Ni-P film with a plating bath 1 of 9.0pH at 60 deg.C. The bath 1 gives small coercive force and a favorable squareness ratio and contains 0.08mol/l cobalt sulfate, 0.02mol/l nickel sulfate, 0.2mol/l sodium hypophosphite, 0.2mol/l sodium tartrate and 0.2mol/ lboric acid. A plated film of 700Angstrom thickness is then formed on said plated film with a plating bath 2 of 9.0pH at 80 deg.C. The bath 2 contains 0.08mol/l cobalt sulfate, 0.02mol/l nickel sulfate, 0.7mol/l sodium hypophosphite, 0.2mol/l sodium tartrate, 0.2mol/l boric acid and 0.2mol/l ammonium sulfate. Solid lines in the figure relate to plated films formed with the plating bath 1. In case of 100Angstrom thickness, the film has 300Oe coercive force (Hc), so a loop is rapidly closed. In case of 800Angstrom thickness, considerably improved 640 Oe Hc and 0.85 squareness ratio are attained.
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