| 摘要 |
PURPOSE:To improve durability without deteriorating the electromagnetic conversion characteristic of a medium by providing approximately concentrical grooves on the surface of a substrate on the side where a magnetic layer is formed or on the surface of an underlying layer provided thereon. CONSTITUTION:A magnetic disk 1 has the underlying layer 3 on the nonmagnetic substrate 2 and has usually an intermediate layer 4 consisting of a nonmagnetic metal on the underlying layer 3 and a thin magnetic metallic layer 5 thereon. A protective film 6 consisting of a nonmagnetic metal, a carbon protective film 7 and a top coat layer 8 are successively laminated on the magnetic layer 5. Al or Al alloy is preferably used as the nonmagnetic substrate 2 and is formed to a disk shape having preferably 1.2-1.9mm thickness. A layer contg. compsn. such as Ni-P or Ni-Cu-P is formed by an electroless plating method, etc., as the underlying layer 3. The underlying layer 3 is formed to 3-50mum film thickness and the grooves 9 which are approximately concentrical and have the distribution and depth irregular in the diametral direction are provided on the surface thereof to about 0.001-0.2mum depth. The attraction characteristic and durability are thereby improved without deteriorating the electromagnetic conversion characteristic.
|
