Magnetic-disk substrate, magnetic disk, and method for manufacturing magnetic-disk substrate
US-10319403-B2 · Jun 11, 2019 · US
Magnetic-disk substrate, magnetic disk, and magnetic-disk drive device
US11094345B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-11094345-B2 |
| Application number | US-201916395850-A |
| Country | US |
| Kind code | B2 |
| Filing date | Apr 26, 2019 |
| Priority date | Mar 31, 2015 |
| Publication date | Aug 17, 2021 |
| Grant date | Aug 17, 2021 |
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Abstract
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A magnetic-disk substrate has a pair of main surfaces, and an arithmetic average roughness Ra of each of the main surfaces is 0.11 nm or less. The arithmetic average roughness Ra is a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. The magnetic-disk substrate is made of glass or aluminum alloy.
First claim
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What is claimed is: 1. A magnetic-disk substrate, comprising: a pair of main surfaces, an arithmetic average roughness Ra of each of the main surfaces being 0.11 nm or less, the arithmetic average roughness Ra being a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member, and the magnetic-disk substrate being made of glass or aluminum alloy. 2. The magnetic-disk substrate according to claim 1 , wherein in surface unevenness of the main surfaces, an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of the surface unevenness is 25 nm 2 /protrusion or less. 3. The magnetic-disk substrate according to claim 1 , wherein in surface unevenness of the main surfaces, an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of the surface unevenness is 20 nm 2 /protrusion or less. 4. The magnetic-disk substrate according to claim 1 , wherein in surface unevenness of the main surfaces, an average area of regions occupied by a plurality of protrusions having a height of 0.2 nm or more from an average plane of the surface unevenness is 12 nm 2 /protrusion or less. 5. The magnetic-disk substrate according to claim 1 , wherein a difference between an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of surface unevenness of the main surfaces and an average area of regions occupied by a plurality of protrusions having a height of 0.2 nm or more from the average plane of the surface unevenness is 13 nm 2 /protrusion or less. 6. The magnetic-disk substrate according to claim 1 , wherein the magnetic-disk substrate is a magnetic-disk glass substrate made of glass. 7. The magnetic-disk substrate according to claim 6 , wherein a glass transition point of glass of the magnetic-disk glass substrate is 600° C. or more. 8. The magnetic-disk substrate according to claim 1 , wherein the magnetic-disk substrate is a substrate for a magnetic disk having a nominal 2.5-inch size and a recording density of 750 gigabytes or more per magnetic disk, or for a magnetic disk having a nominal 3.5-inch size and a recording density of 1000 gigabytes or more per magnetic disk. 9. The magnetic-disk substrate according to claim 1 , wherein the magnetic-disk substrate is a substrate for a magnetic disk that has a nominal 3.5-inch size. 10. The magnetic-disk substrate according to claim 1 , wherein the magnetic-disk substrate is a substrate for energy-assisted magnetic recording. 11. A magnetic disk, wherein a magnetic film is formed on the magnetic-disk substrate according to claim 1 . 12. A magnetic-disk drive device comprising: the magnetic disk according to claim 11 . 13. A magnetic-disk substrate, comprising: a pair of main surfaces, in surface unevenness of the main surfaces, an average area of regions occupied by a plurality of protrusions having a height of 0.1 nm or more from an average plane of the surface unevenness being 25 nm 2 /protrusion or less, the surface unevenness of the main surfaces being a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member, and the magnetic-disk substrate being made of glass or aluminum alloy. 14. The magnetic-disk substrate according to claim 13 , wherein an arithmetic average roughness Ra of each of the main surfaces is 0.15 nm or less. 15. The magnetic-disk substrate according to claim 13 , wherein in the surface unevenness of the main surfaces, the average area of the regions occupied by the plurality of protrusions having a height of 0.1 nm or more from the average plane of the surface unevenness is 20 nm 2 /protrusion or less. 16. The magnetic-disk substrate according to claim 13 , wherein in the surface unevenness of the main surfaces, the average area of regions occupied by the plurality of protrusions having a height of 0.2 nm or more from the average plane of the surface unevenness is 12 nm 2 /protrusion or less. 17. The magnetic-disk substrate according to claim 13 , wherein a difference between the average area of the regions occupied by the plurality of protrusions having a height of 0.1 nm or more from the average plane of the surface unevenness and an average area of regions occupied by a plurality of protrusions having a height of 0.2 nm or more from the average plane of the surface unevenness is 13 nm 2 /protrusion or less. 18. The magnetic-disk substrate according to claim 13 , wherein the magnetic-disk substrate is a magnetic-disk glass substrate made of glass, and a glass transition point of glass of the magnetic-disk glass substrate is 600° C. or more. 19. A magnetic disk, wherein a magnetic film is formed on the magnetic-disk substrate according to claim 13 . 20. A magnetic-disk drive device comprising: the magnetic disk according to claim 19 .
Assignees
Inventors
Classifications
Aluminium or titanium elemental or alloy substrates · CPC title
Composites or coated substrates · CPC title
Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic · CPC title
manufacturing base layers · CPC title
- G11B5/82Primary
Disk carriers · CPC title
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- What does patent US11094345B2 cover?
- A magnetic-disk substrate has a pair of main surfaces, and an arithmetic average roughness Ra of each of the main surfaces is 0.11 nm or less. The arithmetic average roughness Ra is a value obtained through measurement using an atomic force microscope provided with a probe having a probe tip provided with a carbon nanofiber rod-shaped member. The magnetic-disk substrate is made of glass or alum…
- Who is the assignee on this patent?
- Hoya Corp
- What technology area does this patent fall under?
- Primary CPC classification G11B5/82. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Tue Aug 17 2021 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 5 related publications on this page (citations in our corpus or others sharing the same primary CPC).