Substrate for magnetic disk
US8241516B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 16, 2008 |
| Grant date | Aug 14, 2012 |
| Priority date | — |
| Expiry date | Nov 27, 2030 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24355
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method for manufacturing a substrate for a magnetic disk, including the steps of (a) polishing a substrate with a polishing composition A containing alumina abrasives having an average particle size of from 0.05 to 0.5 μm, and an oxidizing agent, and (b) polishing the substrate with a polishing composition B containing silica particles having an average particle size of from 0.005 to 0.1 μm; a substrate for a magnetic disk, obtainable by the method for manufacturing a substrate for a magnetic disk; and a substrate for a magnetic disk having the following surface properties of a long-wavelength waviness of 0.05 nm or more and 0.3 nm or less, and an AFM surface roughness of 0.03 nm or more and 0.2 nm or less. The substrate for a magnetic disk may be suitably used in the manufacture of a hard disk having a high recording density. Especially, a hard disk having a recording density of 50 G bits or more per square inch may be industrially manufactured.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.