Magnetic disc

Disclosed herein is a substrate for a magnetic disc comprising a glass substrate having fine protrusions on its surface, the protrusions having a height of 50 to 1000 ANGSTROM , a width of 0.01 to 1 mu m, a density of 10 to 1000 per 100 mu m2 and an area ratio of 0.1 to 50%, and a ratio of peak heig...

Ausführliche Beschreibung

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Bibliographische Detailangaben
Hauptverfasser: MOURI, DAISUKE, KUROE, TORU, YOKOYAMA, FUMIAKI
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:Disclosed herein is a substrate for a magnetic disc comprising a glass substrate having fine protrusions on its surface, the protrusions having a height of 50 to 1000 ANGSTROM , a width of 0.01 to 1 mu m, a density of 10 to 1000 per 100 mu m2 and an area ratio of 0.1 to 50%, and a ratio of peak height on a mean line (Rp) to maximum height (Rmax) with respect to surface roughness of the substrate being at least 60%. Further, a process for preparing the substrate and a magnetic disc having the substrate are disclosed. Because the substrate according to the present invention has appropriate protrusions on its surface, a friction force and an adsorbing force between a head and a magnetic disc can be reduced, leading to the improvement of the CSS and the anti-head stick properties. In addition, the S/N ratio is not affected because the fine concave portions formed on the surface of the substrate are shallow.