| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a glass substrate for an HDD by which deformation of a magnetic recording medium can be suppressed when the magnetic recording medium is mounted on a hard disk drive. <P>SOLUTION: A glass substrate 50 for an HDD has a circular hole 50a at a center part. When the radius of the circular hole is r, and the maximum value, minimum value, and average value of the thickness of the glass substrate 50 are tmax, tmin, and tave, respectively, measured along a circle C concentric with the circular hole 50a present between a first circle c1 having a radius of r+0.30 mm and concentric with the circular hole 50a and a second circle c2 having a radius of r+4 mm and concentric with the circular hole 50a, the following relationship is satisfied: tmax≤tave+0.05 μm and tmin≥tave-0.05 μm. <P>COPYRIGHT: (C)2013,JPO&INPIT |
