A glass substrate for a magnetic disk of the invention is a disk-shaped glass substrate for a magnetic disk where the substrate has a main surface and end face and is subjected to chemical reinforcement treatment, and is characterized in that the penetration length in the uppermost-portion stress layer...http://www.google.de/patents/US8119267?utm_source=gb-gplus-sharePatent US8119267 - Glass substrate for magnetic disk and manufacturing method of the same
