Patent Number: 6,333,089

Title: Substrate for information recording disk, mold and stamper for injection molding substrate, and method for making stamper, and information recording disk

Abstract: A cavity surface-forming plate of a mold for injection-molding a plastic substrate is coarsely polished, and then a surface for defining a cavity is applied with electroless Ni--P plating. The surface of the plating is polished with abrasive grains to obtain surface roughness of Ra.ltoreq.2.0 nm and Rmax.ltoreq.22 nm. The plastic substrate molded with the mold has smoothness equivalent to the polished plating surface. A concave-convex pattern for forming pits may be formed on the cavity surface. A magnetic disk or an optical disk provided with the substrate makes it possible to realize the near contact system for a magnetic or magneto-optical head. Thus, it is possible to realize high density recording.

Inventors: Hirata; Hiroyuki (Ohtsu, JP), Araki; Tatsuo (Ohtsu, JP), Ishizaki; Osamu (Suita, JP), Daimon; Hideo (Ibaraki, JP), Kokufuda; Yasuhiko (Kyoto, JP), Maro; Tsuyoshi (Kyoto, JP), Aihara; Makoto (Fujisawa, JP)

Assignee: Hitachi Maxwell, Ltd.

International Classification: G11B 5/62 (20060101); B32B 003/02 ()

Expiration Date: 12/25/2018