JPH0758542B2 - Thin film type magnetic recording medium - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a flexible thin film magnetic recording medium having a recording layer made of a magnetic thin film, and more particularly to a flexible thin film magnetic recording medium having excellent wear resistance. It is a thing.

[Prior Art] In recent years, the demand for high-density recording has increased more and more, and the one using a ferromagnetic metal layer as a magnetic recording layer, and Japanese Patent Publication No. 58-
A method using a cobalt-based alloy layer having perpendicular magnetic anisotropy as disclosed in Japanese Patent No. 91 has been proposed. However, in the case of a thin film type magnetic recording medium using such a magnetic thin film as the magnetic recording layer, there is a drawback that it is easily worn or damaged due to a large frictional resistance with the magnetic recording head and lacks in durability.

For this reason, various proposals have heretofore been made in which an organic polymer, high-hardness metal, ceramics or the like is further provided as a protective layer on a ferromagnetic metal thin film.

However, the wear resistance of the thin film type magnetic recording medium, that is, the life of the magnetic recording medium when the magnetic recording medium is repeatedly run on the magnetic recording head is inferior to the conventional coating type magnetic recording medium, and is practically used. It is still in a state of not being enough.

[Object of the Invention] The present invention has been made in view of the present circumstances, and an object of the present invention is to provide a flexible thin film type magnetic recording medium having excellent wear resistance.

[Structure / Operation of the Invention] The above-mentioned object is achieved by the present invention described below. That is, the present invention is a flexible thin film magnetic recording medium characterized in that a protective layer made of copper oxide is provided in the thin film magnetic recording medium in which the recording layer is a magnetic thin film.

The present invention is applicable to all flexible thin film magnetic recording media having a known ferromagnetic thin film as a recording layer. Specifically, those provided with a thin film layer of γ-iron oxide on the substrate, and provided with a ferromagnetic metal thin film layer for inner surface recording made of metal such as iron, cobalt, nickel or alloys thereof. , A ferromagnetic metal thin film layer for perpendicular recording made of a cobalt-based alloy thin film having perpendicular magnetic anisotropy, or a metal layer having high magnetic permeability such as iron, permalloy, cobald niobium zircon alloy, etc. There are known in-plane or perpendicular recording thin-film magnetic recording media such as the one on which the above-mentioned perpendicular recording metal thin film layer is successively formed thereon. Above all, the recording layer shown in the examples is preferably applied to a perpendicular magnetic recording medium composed of an alloy thin film containing cobalt-chromium as a main component. A flexible substrate made of a polymer film such as polyester or polyimide is used as the substrate.

These magnetic recording media are manufactured by forming a magnetic thin film serving as a recording layer on a substrate. The thin film forming method includes a vacuum vapor deposition method and a sputtering method known as continuous thin film forming methods, and further, JP-A-57-100627 and 59-59.
A physical vapor deposition method such as a facing target type sputtering method, a plating method, or the like, which is known in Japanese Patent No. 193528, is used.

The protective layer of copper oxide of the present invention is naturally provided as a continuous thin film layer on the recording layer of the magnetic recording medium. For forming this protective layer, a physical vapor deposition method or the like is used as in the case of forming the recording layer described above.

In the copper oxide according to the present invention, the number of oxygen atoms bonded to one copper atom is unclear, but the copper oxide produced by the above method is referred to as the copper oxide of the present invention.

The present invention realizes durability of several million or more passes required for a practical level by providing the protective layer made of copper oxide on the recording layer made of a magnetic thin film as described above.

Examples will be described below together with comparative examples.

Examples and Comparative Examples FIG. 1 shows an example of the configuration of the present invention, which is a flexible double-sided perpendicular magnetic recording medium for a floppy disk.
A polyethylene terephthalate film having a diameter of 5.25 inches and a thickness of 50 μm is used as a substrate 1, and 0.5 μm of a high magnetic permeability thin metal layer 2 made of a nickel-iron alloy having 0.5 μm on both sides thereof.
And a perpendicular magnetic recording layer 3 made of an alloy thin film of cobalt-chromium (chromium: 20 wt%) are sequentially laminated by a facing target type sputtering method similarly to JP-A-57-100627, and copper oxide ( A protective layer 4 of copper oxide having a thickness of about 200 Å is laminated by a radio frequency (RF) magnetron sputtering method in a 100% argon gas atmosphere using a CuO) powder target (Example).

In addition, as a comparative example, tungsten oxide (Comparative Example 1), titanium oxide (Comparative Example 2), tantalum oxide (Comparative Example 3), tin oxide (Comparative Example 4) having the same structure as that of the Example except for the protective layer were used as protective layers. ) Is the same as in the example, and is subjected to high-frequency magnetron sputtering using an oxide powder target for about 200
Å A sample laminated to have a thickness was prepared.

Table 1 shows that these samples were made of alumina titanium carbide (commonly known as AlTiC (AlTiC) with a sliding part (head slider part) instead of the magnetic head having a spherical surface with a radius of curvature of 50 mm.
C)) commercially available floppy disk drive with a dummy head set, the head was fixed to the same track, and the surface roughness of the sample was measured after rotating for 3 million passes at a head pressing load of 18 g and a rotation speed of 1 m / sec. The evaluation results are shown below.

That is, for durability evaluation, the surface roughness of the sample before and after the sliding test was obtained as the center line average roughness CLA using a surface roughness meter (SURFCOM, manufactured by Tokyo Seimitsu Co., Ltd.), and the CLA value after sliding was calculated. It was determined by the relative surface roughness divided by the CLA value before sliding and the maximum depth (μm) of wear scratches formed on the medium.

Table 2 shows the results after 10 million passes with the radius of curvature of the sliding surface of the dummy head set to 30 mm, the pressure load of the head set to 4 g, and the rotation speed of 3 m / sec for the conditions in Table 1. Show.

As is clear from the table, in the example in which the copper oxide of the present invention was used as a protective layer, there was almost no wear at 3 million passes, and some wear was sometimes seen at 10 million passes, but it was very slight and still not sufficient. Ready to use. That is,
It is understood that the present invention can provide a long-awaited thin-film magnetic recording medium having a sufficiently practical level of sliding durability.

From the point of view, the present invention is not limited to the floppy disk and the perpendicular magnetic recording medium shown in the embodiments, and it goes without saying that it can be applied to all flexible thin film magnetic recording media. It is also clear that the above-mentioned film forming means other than the embodiment can be applied to the manufacturing method of the recording layer and the protective layer.

[Brief description of drawings]

FIG. 1 is a partial side sectional view showing the configuration of an embodiment of the present invention. 1: substrate, 2: high permeability metal thin film layer, 3: cobalt-chromium alloy thin film layer, 4: copper oxide protective layer

Claims (5)

[Claims] 1. A flexible thin film magnetic recording medium having a recording layer made of a magnetic thin film, wherein a protective layer made of copper oxide is provided. 2. The thin-film magnetic recording medium according to claim 1, wherein the recording layer is a perpendicular recording layer. 3. The thin film magnetic recording medium according to claim 2, wherein the perpendicular recording layer is an alloy thin film containing cobalt-chromium as a main component. 4. The thin film magnetic recording medium according to claim 1, 2 or 3, wherein the protective layer made of copper oxide is formed by a physical vapor deposition method. 5. The thin-film magnetic recording medium according to claim 1, 2, 3, or 4, wherein the magnetic recording medium is a magnetic disk.