Hydrofluoric acid etched substrate for information recording medium
AssigneeNippon Sheet Glass Co., Ltd.
InventorsJunji Kurachi, Akihiro Koyama, Nobuyuki Yamamoto, Yasuhiro Saito, Kazuishi Mitani, Koichi Ataka, Yoshihiro Matsuno
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Abstract
A glass substrate for an information recording medium has an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %. The glass substrate has a recording surface having an average surface roughness Ra smaller than 0.3 nm.
Claims14
A glass substrate for an information recording medium having at least one surface as a recording surface, the glass substrate having an acid resistance represented by an etching rate of at most 45 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %, at least the recording surface having an average surface roughness Ra smaller than 0.3 nm.
A glass substrate for an information recording medium having at least one surface as a recording surface, the glass substrate having an acid resistance represented by an etching rate of at most 30 nm/min. upon contact with a hydrofluoric acid having a temperature of 50° C. and a concentration of 0.1 weight %, at least the recording surface having an average surface roughness Ra smaller than 0.3 nm.
Dependencies are inferred from the claim text.