Disk-like glass substrate with magnetic recording medium and manufacturing method thereof

Abstract

A disk-like glass substrate with magnetic recording medium and a manufacturing method thereof aim to improve productivity. The disk-like glass substrate does not contact with a wall surface of a cutting slot when being cut out from a glass blank. The method comprises a cutting step, a polishing step, and a cleaning step. In the cutting step, the substrate is cut out of the glass blank along a circular contour in the surface by means of a pulse laser beam with an irradiation pulse width greater than 1 femtosecond and less than 1 nanosecond, so that the cutting slot wider than 10 micrometer is formed along the contour. In the polishing step, a main surface of the substrate is polished. In the cleaning step, the surface of the substrate is cleaned.

Description

technical field [0001] The present invention relates to a disk-shaped glass substrate for magnetic recording media and a method for manufacturing a disk-shaped glass substrate for magnetic recording media. Background technique [0002] For example, in the manufacturing method of the disc-shaped glass substrate for magnetic recording medium, there is the manufacturing method that carries out following each step successively, namely: (1) cutting out step, (2) shape processing step (chamfering processing step), ( 3) Polishing step, (4) End surface grinding step, (5) Main surface grinding step, (6) Chemical strengthening step, (7) Magnetic layer forming step (for example, refer to Patent Document 1). [0003] Here, each of the above steps will be described. [0004] (1) In the cutting out process, prepare (cut) a quadrangular glass base plate corresponding to the size of the disc-shaped glass substrate in advance, and use a glass cutter to form a glass plate along the disc-shap...

AI Technical Summary

Problems solved by technology

[0013] In addition, in the shape processing process, when the end face of the disc-shaped glass is processed, a draft is formed on the end face, so not only is the load on the rotating grindstone uneven, but also the grinding of the chamfered surface and the side wall surface increased burden on

[0014] In addition, when the end face and chamfering of the disc-shaped glass substrate are performed using a rotating grindstone, processing cracks caused by the grinding process will occur on the end face and the chamfering of the disc-shaped glass substrate, so even if the end face The grinding process also cannot remove the machining cracks, resulting in residual machining cracks

In this case, chipping, cracking, etc. may occur due to remaining processing cracks (processing-altered layer) during handling and processing of the disc-shaped glass substrate.

[0015] In addition, in the process of forming a thin film such as a magnetic layer on the main plane of a disk-shaped glass substrate to produce a magnetic recording medium, there may be a problem that when the disk-shaped glass substrate for a magnetic recording medium is heated and cooled, residual Cracks (work-altered layers) on end faces or chamfered faces spread to cause chipping and cracking of disk-shaped glass substrates for magnetic recording media

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