SELECTIVELY CHEMICALLY REINFORCED DATA STORAGE DISK AND ITS MANUFACTURE

摘要

PROBLEM TO BE SOLVED: To obtain a data memory disk which has excellent failure resistance and surface uniformity and contributes to shortening of production cycle time and reduction of a production cost by coating the selected parts of a disk type glass substrate with a reinforcing agent, thereby enhancing the strength over the entire part of the disk type glass substrate and its production. SOLUTION: The disk type glass substrate 37 has an upper surface 70, a lower surface 72, an inside diameter edge 76 and an outside diameter edge 78. The inside diameter part of the glass disk substrate 37 where the compressive load level generated in a disk clamping device acts most highly is greatly reinforced if the inside diameter diffused layer 86 is formed down to a sufficient depth DID by subjecting only the inside diameter edge 76 part of the glass substrate 37 to chemical reinforcement. As a result, the glass data memory disk having the upper disk surface 70 and lower surface 72 which have high reliability and are free from distortions is obtd. The production cycle time of the glass data memory disk is shortened and the production cost is reduced.