Magnetic disk substrate, magnetic disk, and magnetic disk device

摘要

It is an object to provide a magnetic disk substrate highly reliable to prevent the occurrence of crash failure even if a magnetic disk is rotated at high speed, and suitable for a hard disk that starts and stops by the load/unload method, and a magnetic disk using such a substrate. The representative structure of a magnetic disk substrate is a disk-shaped glass substrate 10 having a generally flat main surface 11, an end face 12, a chamfered face 13 formed between the main surface 11 and the end face 12, and an offset portion, at the periphery of the main surface 11, raised or lowered with respect to a flat surface, other than the periphery, of the main surface 11, and characterized in that the magnitude of the offset portion is approximately uniform over the entire circumference of the glass substrate 10.

主权项

1. A magnetic disk substrate being a disk-shaped substrate and having a generally flat main surface, an end face, a chamfered face formed between the main surface and the end face, and an offset portion, at a periphery of the main surface, raised with respect to a flat surface, other than the periphery, of the main surface, wherein:
said offset portion is formed over the entire circumference of said substrate; when a distance from a center of the substrate to the end face is 100%, an extreme portion where rising is maximum in the offset portion is located in a range of 92.0 to 97.0% from the center of the substrate; in the main surface, a circularity of a circle formed by the extreme portion is 400 μm or less; and the substrate is configured to be adapted to a magnetic disk of a load/unload type in which a magnetic head is loaded and unloaded with respect to the main surface of the magnetic disk through its outer periphery.