Hoya Corporation

Kouichi Tamoto

Tomoyuki Yamaguchi

Takuhiro Hirakawa

Yasunari Hirano

An object of the invention is to remove effectively metallic contaminants adhering to the glass substrate surfaces without increasing roughness of the glass substrate surfaces in the glass substrate for a magnetic disk. In a manufacturing method of a glass substrate for a magnetic disk having a cleaning step of the glass substrate, the cleaning step comprising a cleaning treatment of contacting the glass substrate with an alkaline aqueous solution having a gluconate in concentration of not less than 0.05 wt % and not more than 2 wt % added thereto and a pH of not less than 9 and not more than 11 is appended.

Manufacturing method of a glass substrate for a magnetic disk

An object of the invention is to remove effectively metallic contaminants adhering to the glass substrate surfaces without increasing roughness of the glass substrate surfaces in the glass substrate for a magnetic disk. In a manufacturing method of a glass substrate for a magnetic disk, a cleaning step comprising a treatment of contacting the glass substrate with a cleaning liquid containing peroxodisulfate and having a pH of not less than 2 and not more than 4 is appended. In addition, an example of the cleaning liquid can be prepared by adding sodium peroxodisulfate to an acidic solution.

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Tokyo, Japan

Kouichi Tamoto