JPS62107432A - Thin film type magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a thin film type magnetic recording medium having excellent wear resistance by successively laminating thin high permeability metallic film layers, thin alloy film layers and protective layers consisting of zinc oxide, yttrium oxide or tin oxide on a substrate. CONSTITUTION:The thin high permeability metallic film layers 2 consisting of 0.5mu Ni-iron alloy and the vertical magnetic recording layers 3 consisting of 0.15mu thin cobalt-chromium alloy films are laminated by a sputtering method on both surfaces of the substrate 1 and further the protective layers 4 consisting of 200Angstrom zinc oxide are formed thereon. Since the protective layers consisting of the zinc oxide are provided in the above-mentioned manner, the thin film type recording medium having excellent sliding durability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a thin-film magnetic recording medium in which the recording layer is made of a magnetic thin film, and more particularly to a thin-film magnetic recording medium with excellent wear resistance.

[Prior art] In recent years, the demand for high-density recording has become higher and higher, and the use of a ferromagnetic metal layer as a magnetic recording layer has become increasingly popular.
A device using a cobalt-based alloy layer having perpendicular magnetic anisotropy has been proposed, such as in Japanese Patent No.-91. However, in the case of an i-model magnetic recording medium using such a magnetic thin film as a magnetic recording layer, there is a drawback that it is susceptible to wear and damage and lacks durability because of the large frictional resistance with the magnetic recording head.

For this reason, various proposals have been made in the past in which an organic polymer, high hardness metal, ceramics, etc. are further provided as a protective layer on the ferromagnetic metal R1lu.

However, the abrasion resistance of the thin-film magnetic recording medium, that is, the life span of the magnetic recording medium when the magnetic recording medium is repeatedly run on a magnetic recording head, is inferior to that of conventional coated magnetic recording media, and is not practical. However, the situation is still not satisfactory.

[Purpose of the Invention] The present invention was made in view of the current situation, and is aimed at a thin film type magnetic recording medium having excellent wear resistance.

[Structure and operation of the invention] The above objects are achieved by the invention as follows.

That is, the present invention provides a thin film magnetic recording medium in which the recording layer is made of a magnetic thin film.

This is a thin film magnetic recording medium characterized by providing a WS layer made of yttrium oxide or tin oxide.

The present invention is applicable to all thin-film magnetic recording media having known ferromagnetic thin films as recording layers. Specifically, these include those provided with a thin film layer of gamma iron oxide on a substrate, and a 7fJ film layer of a ferromagnetic metal for in-plane recording made of metals such as iron, cobalt, nickel, or alloys thereof. A material with a ferromagnetic metal λ9 film layer for perpendicular recording made of a cobalt-based alloy thin film with perpendicular magnetic anisotropy, or a material with high magnetic permeability such as iron, permalloy, cobalt-niobium-zircon alloy, etc. There are known thin film magnetic recording media for in-plane or perpendicular recording, such as those in which a metal thin film layer for perpendicular recording is sequentially formed on a metal layer. Among these, it is preferably applied to a perpendicular magnetic recording medium made of an alloy thin film mainly composed of cobalt-chromium as shown in the embodiment. The substrate may be a polymer film such as polyester or polyimide,
glass plate.

Aluminum alloy plates, etc. are used for magnetic tape.

Floppy disk, hard disk, etc. are selected depending on the purpose.

These magnetic recording media are manufactured by forming a magnetic thin film serving as a recording layer on a substrate. This thin film formation method includes the vacuum evaporation method, the sputtering method, which is known as a method for forming a continuous 7IJ film, and the facing target sputtering method, which is known in JP-A-57-100627, JP-A-59-193528, etc. A physical vapor deposition method such as a method, a plating method, or the like is used.

Further, the protective layer of zinc oxide, yttrium oxide or tin oxide of the present invention is naturally provided as a continuous thin film layer on the recording layer of the magnetic recording medium.

Physical vapor deposition or the like is used to form this protective layer, as in the formation of the recording layer described above.

Although the number of oxygen atoms bonded to one metal atom is unclear in the metal oxides of zinc oxide, yttrium oxide, and tin oxide that constitute the protective layer of the present invention, the metal oxide produced by the above method is The substance is referred to as the metal oxide of the present invention.

In the present invention, by providing a protective layer made of zinc oxide, yttrium oxide, or tin oxide as described above on the recording layer made of a magnetic thin film, the number of
It has achieved durability of over 00,000 passes.

[Example, Comparative Example] FIG. 1 shows a configuration example of the present invention, which is a flexible double-sided perpendicular magnetic recording medium for a floppy disk.

The base 1 is a polyethylene terephthalate film with a diameter of 5.25 inches and a thickness of 50 μm, and a 0.5 μm film is coated on both sides of the polyethylene terephthalate film.
a thin metal layer 2 with high magnetic permeability made of a nickel-iron alloy of m;
0.15μm cobalt chromium (chromium: 20wt
perpendicular magnetic recording layer 3 made of an alloy thin film of
Similar to Publication No. 7-100627, layers were sequentially laminated by the facing target sputtering method, and a zinc oxide (ZnO) powder target was used as the protective layer 4 on top of that using a radio frequency (RF) magnetron in a 100% argon gas atmosphere. About 200 protective layers of zinc oxide were laminated by sputtering (Example 1). In addition, a sample was prepared with the same structure as in Example 1, but with about 200 layers of yttrium oxide and tin oxide as the protective layer 4 instead of zinc oxide in Example 1 (Example 2.3). Note that these protective layers were formed by high frequency magnetron sputtering using the same oxide powder targets as in Example 1.

In addition, as comparative examples, tungsten oxide (comparative example 1), titanium oxide (comparative example 2), and tantalum oxide (comparative example 3) were used as protective layers with the same structure as in the example except for the protective layer. Table 1 shows that samples with a thickness of about 200 layers were created using the high-frequency magnetron sputtering method using a solid powder target.
A commercially available floppy disk drive device equipped with a dummy head made of alumina titanium carbide (commonly known as At Ti C) with a spherical surface was fixed on the same track, and the head pressing load was 18 g, rotation speed was 1.
The results of the evaluation of the surface roughness of the sample after 3 million bus rotations at m/sec are shown below.

That is, durability evaluation was performed by measuring the surface roughness of the sample before and after the sliding test using a surface roughness meter (SURFCOM).

Calculate the center line average roughness (CLA) using the CLA (manufactured by Tokyo Seimitsu ■), and calculate the relative surface roughness by dividing the CLA value after sliding by the CLA value before sliding, and the maximum depth of wear scratches generated on the media (μm).
This was done by.

Table 1 As is clear from the table, there are 3 examples in which zinc oxide, yttrium oxide, or tin oxide of the present invention is used as a protective IJi.
Although there is some wear after 1,000,000 baths, it is very minor and is in good condition for use. That is, it can be seen that the present invention makes it possible to obtain a long-awaited thin film magnetic recording medium having a sufficient practical level of sliding durability.

In view of its purpose, the present invention is not limited to the floppy disks and perpendicular magnetic recording media shown in the embodiments, but as described above, it can be applied to so-called hard disks such as aluminum disks treated with alumina oxidation, and tungsten tapes. Needless to say, it can be applied to. It is also clear that the above-mentioned film forming means other than the embodiments can be applied to the method of manufacturing the recording layer and the protective layer.

[Brief explanation of drawings]

FIG. 1 is a partial side sectional view showing the configuration of an embodiment of the present invention. 1: Substrate, 2: High magnetic permeability metal thin flfl sound. 3: Cobalt-chromium alloy thin film layer. 4: Protective layer 71. f 1, -) tel 1゛1 "-5

Claims (1)

[Scope of Claims] 1. A thin-film magnetic recording medium in which the recording layer is a magnetic thin film, characterized in that the recording layer is provided with a protective layer made of zinc oxide, yttrium oxide, or tin oxide. 2. Claim 1, wherein the recording layer is a perpendicular recording layer.
Thin-film magnetic recording medium as described in . 3. The thin film magnetic recording medium according to claim 2, wherein the perpendicular magnetic 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, wherein the protective layer made of zinc oxide, yttrium oxide, and tin oxide is formed by physical vapor deposition.