Stock material or miscellaneous articles – Structurally defined web or sheet – Continuous and nonuniform or irregular surface on layer or...
Patent
1996-01-19
1998-12-29
Kiliman, Leszek
Stock material or miscellaneous articles
Structurally defined web or sheet
Continuous and nonuniform or irregular surface on layer or...
428336, 428694T, 428694TS, 428694TR, 428694ST, 428694SG, 428900, 2041922, 20419235, G11B 566
Patent
active
058538470
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a magnetic recording medium and a manufacturing method therefor. In greater detail, the present invention relates to a high density recording medium possessing superior magnetic characteristics which is inexpensive and can be easily produced, as well as to a manufacturing method therefor. The magnetic recording medium in accordance with the present invention is preferably applied to hard disks, floppy disks, magnetic tape, and the like.
BACKGROUND ART
The following technology is known as a conventional magnetic recording medium and a manufacturing method therefor.
FIG. 23 is a schematic diagram showing a hard disk as an example of a magnetic recording medium. In FIG. 23, FIG. 23(a) is a perspective view of the entirety of the magnetic recording medium, while FIG. 23(b) is a cross-sectional view of the section A-A' in FIG. 23(a).
A structure is employed in which a non-magnetic (Ni--P) layer 3 was provided on the surface of an Al substrate 2 which was employed as a base body 1. A Cr base layer 4, a ferromagnetic metallic layer 5, and a protective layer 6 are laminated on this base body 1.
The non-magnetic (Ni--P) layer 3 is formed by means of a plating method or a sputtering method on the surface of an Al substrate 2 which is in the shape of a disk having a diameter of 89 mm (3.5 inch) and a thickness of 1.27 mm (50 mil), and this forms the base body 1. Furthermore, concentric scratches (hereinbelow termed texture) are provided in the surface of the non-magnetic (Ni--P) layer 3 by means of a mechanical grinding process. Generally, the surface roughness of the non-magnetic (Ni--P) layer 3, that is to say, the average center line roughness Ra as measured in the radial direction, is within a range of 5 nm-15 nm. Furthermore, the Cr base layer 4 and the ferromagnetic metallic layer 5 (generally, a Co alloy system magnetic film) are formed on the surface of the base body 1 by means of a plating method, a vapor deposition method, or a sputtering method, and finally, a protective layer comprising carbon or the like which serves to protect the surface of the ferromagnetic metallic layer 5 is provided by means of a sputtering method. The typical thickness of each layer is as follows: the non-magnetic (Ni--P) layer 3 is within a range of 5 .mu.m-15 .mu.m, the Cr base layer 4 is within a range of 50 nm-150 nm, the ferromagnetic metallic layer is within range of 30 nm-100 nm, and the protective layer 6 is within a range of 20 nm-50 nm.
In order to apply a high recording density to the medium described above, among the magnetic characteristics of the medium, it is particularly necessary to increase the coercive force. Recently, customer requirements have been shifting from media having a coercive force within a range of 1200 Oe-1600 Oe to media having a coercive force of 1800 Oe or more. The following technologies were known as methods for increasing the coercive force in magnetic recording media which were conventionally considered in order to respond to such needs. smaller metallic layer
However, the following problems were present in the conventional technologies described above. the ferromagnetic metallic layer. However, the costs thereof are high, and medium noise is also high, so that improvement is expected. With other materials, the effects of the film formation atmosphere are likely to be felt, and it is difficult to realize a coercive force of 1800 Oe or more. thickness of the base layer; however, if the thickness is too greatly reduced, the level of medium noise increases and this is not desirable. by means of, for example, high temperature heat processing after film formation; however, the effects of gas emission within the film formation chamber must be considered, and the like, so that the production process becomes complex, and this is undesirable.
The following technologies are known as manufacturing methods for magnetic recording media. problems were present in the conventional technologies described above. inside of the film formation chamber occurred
REFERENCES:
patent: 5432012 (1995-07-01), Lal
patent: 5466522 (1995-11-01), Freeman
patent: 5607740 (1997-03-01), Nodo
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