Disc substrates for information recording discs and magnetic discs
US6214429A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 30, 1998 |
| Grant date | Apr 10, 2001 |
| Priority date | — |
| Expiry date | Dec 30, 2018 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/21
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Disclosed is disc substrate consisting of SiO.sub.2 --Al.sub.2 O.sub.3 --RO (RO=divalent metal) glasses having high specific elastic modulus of 36.times.10.sup.6 Nm/kg or more or high Young's modulus of 110 GPa or more, high transition temperature of 700.degree. C. or higher (high heat resistance), excellent surface smoothness (surface roughness Ra<5 .ANG.) and high strength. The substrates exhibiting high specific elastic modulus or high Young's modulus and high strength enables to realize thinner magnetic discs and prevent breakdown of magnetic discs. Since glass substrates being composed of the glass have excellent heat resistance and flatness, the substrates can be subjected to heat treatment for improvement of magnetic layer characteristics and realize smaller flying height of magnetic head, i.e., higher recording density.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.