MAGNETIC DISC SUBSTRATE AND MANUFACTURE THEREOF

Japanese Patent JPH1110492

A

PROBLEM TO BE SOLVED: To provide a magnetic disc substrate which is free from grinding dent having a surface roughness of Ra<=0.5 nm and a depth of 5 nm or more and minute undulation and provide a manufacturing method of the magnetic disc substrate which provides good surface roughness, a small depth of the grinding dent, and no minute undulation. SOLUTION: According to this manufacturing method of a magnetic disc substrate, grinding machining is divided into a plurality of steps, grinding is done using a grinding liquid containing abrasive grains of metal oxides having average particle diameter of 0.3 to 5 μm as a grinding process before final grinding machining, and machining is done using a grinding liquid containing colloid particles having average particle diameter of 0.01 μm to 0.3 μm as the final grinding machining in the manufacture of an aluminum magnetic disc substrate after Ni-P plating. The grinding machining by the use of abrasive grains of metal oxides before the final grinding machining may be done by changing a particle diameter of abrasive grains several times. Consequently, it is possible to obtain the magnetic disc substrate which is free from grinding dents having a surface roughness of Ra<=0.5 nm and a depth of 5 nm or more and minute undulation.

TADA KIYOSHI
TOMITA KENJI
AWAYA KURATA
UTASHIRO TOMOYA

JP17656397A

January 19, 1999

June 17, 1997

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SHOWA ALUMINUM CORP

B24B1/00; G11B5/73; G11B5/82; G11B5/84; (IPC1-7): B24B1/00; G11B5/82; G11B5/84

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