Method for manufacturing glass substrate for magnetic recording medium

Abstract

The present invention relates to a method for manufacturing a disk-shaped glass substrate for a magnetic recording medium, having a circular hole at the center thereof, the method including: a shape-forming step of performing shape forming to a glass substrate having a sheet shape; a polishing step of polishing a main surface of the glass substrate; and a cleaning step of cleaning the glass substrate, in which the polishing step includes a finish polishing step of simultaneously polishing both main surfaces of the glass substrate using a polishing slurry containing abrasives having an average particle diameter of 100 nm or less; and the glass substrate polished in the finish polishing step has a thickness deviation among glass substrates polished in the same lot of 1.5 μm or less.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method for polishing a glass substrate to obtain a glass substrate for a magnetic recording medium, having excellent smoothness and edge shape of a main surface thereof, and a method for manufacturing a glass substrate for a magnetic recording medium.BACKGROUND OF THE INVENTION[0002]With increasing high recording density of a magnetic disk in recent years, characteristics required to a glass substrate for a magnetic recording medium are becoming more severe year after year. To achieve high recording density of a magnetic disk, a magnetic head is attempted to pass up to the edge of a glass substrate in order to effectively utilize an area of a main surface of the glass substrate.[0003]In the case that the floating height of the magnetic head is reduced, if a main surface of the magnetic disk is not smooth, there is a possibility that the magnetic head contacts the magnetic disk, thereby causing a fault. Furthermore, if fl...

AI Technical Summary

Benefits of technology

[0010]The present invention has an object to provide a method for polishing a glass substrate, which polishes a glass substrate for a magnetic recording medium, having excellent smoothness and edge shape of a main surface in high productivity, and a method for manufacturing a glass substrate for a magnetic recording medium, including a polishing step using the polishing method.

[0012]The present invention can produce a glass substrate for a magnetic recording medium, having excellent smoothness and edge shape of a main surface in high productivity by setting thickness deviation among glass substrates polished in the same lot to 1.5 μm or less in a finish polishing step which polishes both main surfaces of the glass substrate for a magnetic recording medium.

Problems solved by technology

With increasing high recording density of a magnetic disk in recent years, characteristics required to a glass substrate for a magnetic recording medium are becoming more severe year after year.

In the case that the floating height of the magnetic head is reduced, if a main surface of the magnetic disk is not smooth, there is a possibility that the magnetic head contacts the magnetic disk, thereby causing a fault.

Furthermore, if flatness of an edge shape of a main surface of the magnetic disk is not high, there is a possibility that when the magnetic head is passed up to the edge of the glass substrate, floating posture of the magnetic head is disturbed, and the magnetic head contacts the magnetic disk, thereby causing a fault.

Furthermore, since a polishing rate in the finish polishing step of the glass substrate for a magnetic recording medium is low, there is a possibility that polishing time is prolonged, resulting in poor productivity.Patent Document 1: JP-A 2009-279696

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