| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a glass substrate for a magnetic recording medium capable of obtaining the glass substrate for the magnetic recording medium excellent in parallelism, and further to provide the glass substrate for the magnetic recording medium excellent in the parallelism. <P>SOLUTION: A manufacturing method of a glass substrate for a magnetic recording medium 10 including: a pair of main planes 11; an outer peripheral end surface 12 having an outer peripheral side surface portion 120 and an outer peripheral chamfer 121; and an inner peripheral end surface 13, has a main plane polishing step of polishing the pair of main planes 11 of the glass substrate for the magnetic recording medium 10 held by a carrier by using a double side polishing device. When surface roughness Ra is measured at total 24 points of measuring points of the outer peripheral end surface 12 provided at intervals of 15 degrees of a central angle of the glass substrate for the magnetic recording medium 10 on the outer peripheral end surface 12, in the glass substrate for the magnetic recording medium 10 before being polished in the main plane polishing step, a maximum value of the surface roughness Ra of the outer peripheral side surface portion 120 is 0.5 μm or less and a standard deviation thereof is 0.2 μm or less. <P>COPYRIGHT: (C)2013,JPO&INPIT |
