| 摘要 |
PROBLEM TO BE SOLVED: To provide a substrate for a magnetic disk, which has a surface state suitable for high recording density and high capacity disk. SOLUTION: In a lapping step after Ni-P plating the substrate for the magnetic disk is lapped with lapping cloth, having 80-100 hardness, 0-8% compressibility, 50-90% compressive elasticity modulus and 0.5-0.8 g/cm3 density. The substrate after lapped has a surface state superior in flatness that waviness of 1.0 nm or smaller, minute swelling of 1.5 nm or smaller, dub off of 150 nm or smaller and roll off is 12 nm or smaller. |
