| 摘要 |
PROBLEM TO BE SOLVED: To provide a substrate for a magnetic disk using crystallized glass of high hardness as a plating substrate instead of aluminum or its alloy, and to provide a substrate for a magnetic disk which is small in size, durable against impact during the substrate is carried and which is free from scratches (head snaps) by a magnetic head even when the substrate is used for a note-type or mobile computer having a head which is brought almost in contact with the substrate. SOLUTION: This substrate for a magnetic disk is produced by forming a nickel phosphorus film having 8 to 20μm film thickness on crystallized glass which is polished (lapped) as a finish state and has 0.05 to 0.5μm surface roughness Ra measured by a contact probe type roughness meter. The nickel- phosphorus film is polished by >=3μm polishing amt. and the thickness of the residual plating film is >=5μm.
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