Non-magnetic substrate for magnetic disk, and magnetic disk
AssigneeHoya Corporation
InventorKinobu Osakabe
Life of this patent
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Abstract
A non-magnetic substrate for a magnetic disk includes a substrate main body having two opposing main surfaces, and a metal film that is provided on the main surfaces and is made of a material having a loss factor of 0.01 or more. The non-magnetic substrate has a thickness (T+D) of 0.700 mm or less, the thickness (T+D) being the sum of a thickness T of the substrate main body and a thickness D of the metal film, and a ratio D/T of the thickness D of the metal film to the thickness T of the substrate main body is 0.025 or more.
Claims20
A non-magnetic substrate for a magnetic disk, the non-magnetic substrate comprising:
- a substrate main body having two opposing main surfaces, the substrate main body being a glass substrate main body or an aluminum alloy substrate main body;
- and
- a metal film that is provided on the main surfaces and an outer circumferential edge surface of the substrate main body, and is made of an Ni—P alloy,
- wherein the non-magnetic substrate has a thickness (T+D) of 0.640 mm or less, the thickness (T+D) being the sum of a thickness T of the substrate main body and a thickness D of the metal film,
- a ratio D/T of the thickness D of the metal film to the thickness T of the substrate main body is 0.025 or more, and
- the outer circumferential edge surface of the substrate main body forming an interface with the metal film has a surface roughness maximum height Rz of 0.5 μm or more.
A non-magnetic substrate for a magnetic disk, the non-magnetic substrate comprising:
- a substrate main body having two opposing main surfaces, the substrate main body being a glass substrate main body or an aluminum alloy substrate main body;
- and
- a metal film that is provided on the main surfaces and an outer circumferential edge surface of the substrate main body, and is made of an Ni—P alloy,
- wherein the non-magnetic substrate has a thickness (T+D) of 0.640 mm or less, the thickness (T+D) being the sum of a thickness T of the substrate main body and a thickness D of the metal film,
- a ratio D/T of the thickness D of the metal film to the thickness T of the substrate main body is 0.025 or more, and
- a surface roughness maximum height Rz of the metal film formed on the outer circumferential edge surface of the non-magnetic 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.