Substrate for magnetic disks, and magnetic disk
AssigneeHoya Corporation
InventorKinobu OSAKABE
Life of this patent
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Abstract
A substrate for a magnetic disk includes a substrate main body having two main surfaces, and a film that is provided on the main surfaces and is made of a material having a loss factor of 0.1 or more. The substrate for a magnetic disk including the film has a thickness T of 0.700 mm or less, and a thickness D [mm] of the film provided on the main surfaces and the thickness T [mm] of the substrate for a magnetic disk including the film satisfy a relationship D≥0.0082/T−0.0015.
Claims21
A substrate for a magnetic disk, the substrate comprising:
- a substrate main body having two main surfaces;
- and
- a film that is provided on the main surfaces and is made of a metal material having a loss factor of 0.01 or more,
- wherein the substrate for a magnetic disk including the film has a thickness T of 0.700 mm or less, and
- a total thickness D [mm] of the film provided on the main surfaces and the thickness T [mm] of the substrate for a magnetic disk including the film satisfy Equation (1) below,
- D≥0.0082/T−0.0015 (1),
- the film is provided to cover all surfaces of the substrate,
- a film thickness of the film provided on an edge surface of the substrate is larger than a film thickness of the film provided on the main surfaces, and
- the film is provided such that the film thickness on the edge surface is 110% or more of the film thickness on the main surfaces.
2-12. (canceled)
A substrate for a magnetic disk, the substrate comprising:
- a substrate main body having two main surfaces;
- and
- a film that is provided on the main surfaces and is made of a metal material having a loss factor of 0.01 or more,
- wherein the substrate for a magnetic disk including the film has a thickness T of 0.700 mm or less, and
- a total thickness D [mm] of the film provided on the main surfaces and the thickness T [mm] of the substrate for a magnetic disk including the film satisfy Equation (1) below,
- D≥0.0082/T−0.0015 (1),
- the film is formed on the main surfaces and an outer circumferential edge surface of the substrate main body, and
- the outer circumferential edge surface of the substrate main body forming an interface with the film has a surface roughness maximum height Rz of 0.5 μm or more.
A substrate for a magnetic disk, the substrate comprising:
- a substrate main body having two main surfaces;
- and
- a film that is provided on the main surfaces and is made of a metal material having a loss factor of 0.01 or more,
- wherein the substrate for a magnetic disk including the film has a thickness T of 0.700 mm or less, and
- a total thickness D [mm] of the film provided on the main surfaces and the thickness T [mm] of the substrate for a magnetic disk including the film satisfy Equation (1) below,
- D≥0.0082/T−0.0015 (1),
- the film is formed on the main surfaces and an outer circumferential edge surface of the substrate main body, and
- a surface roughness maximum height Rz of the film formed on the outer circumferential edge surface of the substrate for a magnetic disk is smaller than a surface roughness maximum height Rz of the substrate main body at the outer circumferential edge surface of the substrate main body.
Dependencies are inferred from the claim text.