The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 30, 2002
Filed:
Aug. 04, 2000
Kiyoshi Tada, Oyama, JP;
Kenji Tomita, Oyama, JP;
Kurata Awaya, Oyama, JP;
Tomoya Utashiro, Oyama, JP;
Showa Denko K.K., Tokyo, JP;
Abstract
A magnetic hard disc substrate made of an aluminum alloy for memory devices such as a computer must correspond to an improved structure in which the interval between a head and a medium is made narrower to attain high density recording. In order to prevent head crash, it is required that the magnetic hard disc substrate have a smooth surface and decreased defects. The present invention provides a process for manufacturing a magnetic hard disc substrate made of an aluminum alloy which satisfies the above requirements and also provides a disc substrate which has a surface roughness Ra≦0.5 nm and is free from abrasive flaws with a depth of 5 nm or more and from micro-waviness or provides a disc substrate which has a surface roughness Ra≦5 angstroms and a surface roughness Rmax≦80 angstroms and in which the number of scratches with a depth of 50 angstroms or more is 5 or less and the number of pits with a depth of 50 angstroms or less is 5 or less in the surface.