JPH07254134A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having a protective film having high lubricating property by forming a thin film having fine crystals of diamond in coexistence with fluorinated amorphous carbon as the protective film on a magnetic recording medium layer on a substrate. CONSTITUTION:A plated layer 2 and a magnetic recording medium layer 3 are formed on an Al alloy substrate 1, and then a protective film 7 having fine crystals of diamond in coexistence with fluorinated amorphous carbon is formed by ECR plasma CVD method. To accurately control the hardness and coefft. of friction of the thin film, the component ratio (F/C) of monomers is controlled in an ECR plasma CVD device and the mixing ratio of the diamond fine crystal and fluorinated amorphous carbon is changed so that the film is formed in two stages. In the first stage, the thin film is formed to have hardness coincide with the hardness of the magnetic recording medium layer 3. In the second stage, the coefft. of friction of the thin film is controlled to a desired value. By this method, high lubricating property of the protective film 7 is obtd., the number of the production processes can be decreased, and the production yield is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protective film for a magnetic recording medium of a hard disk for computers.

[0002]

2. Description of the Related Art FIG. 5 is a schematic sectional view showing the structure of a conventional hard disk. In FIG. 5, in this hard disk, the hardness of the magnetic recording medium layer 3 composed of a Co alloy magnetic layer and the like, and the magnetic recording medium layer 3 on both main surfaces of the aluminum alloy substrate 1 on which the plating layer 2 is formed by Ni-P plating. Has a structure in which an amorphous carbon film as the first layer protective film 4 formed in accordance with the above and a lubricating film formed as a second layer protective film 5 by a wet method and then dried are laminated in this order. .

[0003]

However, the disk having the above-mentioned structure requires a lot of man-hours for manufacturing the second layer protective film formed by the wet method and has a low yield. Therefore, the disk should be changed to the dry method. Is desirable. The present invention has been made to solve this problem, and a technical object thereof is to provide a magnetic recording medium having a lubricating protective film which can be formed by a dry method.

[0004]

In order to solve the above-mentioned problems, the magnetic recording medium of the present invention has the following protective film which can be formed by a dry method. It comprises a first layer of an amorphous carbon thin film and a second layer of a fluorinated amorphous carbon thin film.

It can be formed by the ECR plasma CVD method and is composed of a thin film in which diamond microcrystals and fluorinated amorphous carbon coexist. It can be formed by the ECR plasma CVD method and is composed of a plurality of thin films having different mixing ratios of diamond microcrystals and fluorinated amorphous carbon.

[0006]

The lubricity protective film used in the magnetic recording medium of the present invention can be formed by adjusting the fluorine content of the monomer by utilizing the fluorination reaction of the amorphous carbon film by plasma polymerization. CVD
The hardness of the protective film can be made to match the hardness of the magnetic recording medium layer by adding the characteristic of the method, and the friction coefficient can be set to one layer as a desired value. Then, the hardness and the friction coefficient can be precisely controlled. It is possible to reduce the number of steps and improve the yield as compared with the conventional wet method.

[0007]

EXAMPLES The present invention will be described below based on examples. The structure of the recording medium of the present invention is shown in FIGS. 1 to 3. First, in forming a lubricity protective film by a dry method,
With reference to FIG. 4, description will be given of a diagram showing the characteristics of the film, which varies depending on the proportion of fluorine content, when a fluorine-containing monomer is added to a raw material monomer that produces amorphous carbon, according to the production method. FIG. 4 is a diagram in which the horizontal axis is the ratio of carbon to fluorine (F / C) and the vertical axis is the hardness and friction coefficient of the thin film, and the dotted line in FIG. ) Indicates the friction coefficient by the plasma polymerization method, the solid line (b) indicates the hardness by the plasma polymerization method,
The shaded area A represents the required hardness level range, and the area B represents the required friction coefficient level range.

As shown in FIG. 4, the higher the fluorine content of the raw material monomer, the lower the friction coefficient of the obtained thin film. Therefore, by adjusting the component ratio (F / C) of the monomer according to the desired coefficient of friction and then applying the plasma CVD method as the second layer protective film, it is possible to form a lubricous protective film by the dry method. is there. The structure of the magnetic recording medium thus manufactured is shown in the schematic cross-sectional view of FIG. 1, and the same parts as those in FIG. 5 are represented by the same reference numerals. In this magnetic recording medium, the aluminum alloy substrate 1 has a plated layer 2, the magnetic recording medium layer 3 formed thereon, and the amorphous carbon film as the first-layer protective film 4 formed thereon. As the layer protective film 6, a fluorinated amorphous carbon film formed by a plasma polymerization method is formed.

However, since this method focuses on the friction coefficient and tries to obtain the lubricity of the thin film at the expense of hardness, it can be applied only to the second protective layer 4. Therefore, instead of using an ordinary plasma CVD device, ECR
(Electron Cyclotron Reson
ans) By carrying out the same process using a plasma CVD apparatus, the thin film produced will contain diamond microcrystals due to the effect of high-density plasma peculiar to ECR, and the hardness of the thin film will be improved. Therefore, it is possible to increase the content of fluorine to maintain the hardness level and obtain a desired friction coefficient.

The structure of the magnetic recording medium thus obtained is shown in the schematic sectional view of FIG. 2, and the same parts as in FIG. In this magnetic recording medium, the plating layer 2 is formed on the aluminum alloy substrate 1 and the magnetic recording medium layer 3 is formed thereon as in the conventional case.
And a protective film 7 in which microcrystals of diamond and fluorinated amorphous carbon coexist by ECR plasma CVD method. In this case, the protective film 7 does not need to have two layers and may have only one layer.

When it is necessary to accurately control the hardness and friction coefficient of the thin film, the ECR plasma CV
In the D device, the monomer component ratio (F / C) was adjusted to change the mixing ratio of the diamond microcrystals and the fluorinated amorphous carbon, and the film formation was performed in two steps, and the hardness of the thin film in the first step. May be made to match the hardness of the magnetic recording medium layer 3, and the friction coefficient of the thin film may be adjusted to a desired value in the second step.

FIG. 3 is a schematic sectional view showing the structure of the obtained magnetic recording medium, and the same parts as those in FIGS. 1 and 2 are represented by the same reference numerals. In this magnetic recording medium, a plating layer 2 is formed on an aluminum alloy substrate 1, a magnetic recording medium layer 3 is formed thereon, and a first layer protective film 8 E is formed on the plating layer 2 as in the conventional case.
By the CR plasma CVD method, a film having the same hardness as the magnetic recording medium layer 3 in which diamond microcrystals and fluorinated amorphous carbon coexist, and a second layer protective film 9 of the same kind having a desired coefficient of friction. It is a thin film formed.

[0013]

In the magnetic recording medium of the present invention, the protective film is formed by the dry method by utilizing the fluorination reaction of the amorphous carbon thin film by the plasma polymerization to appropriately determine the content ratio of fluorine added to the raw material monomer. Can be formed by using the same, a high lubricity of the protective film can be obtained, and particularly by applying the ECR plasma CVD method, the obtained lubricous thin film can be adjusted to the hardness of the magnetic recording medium layer in the same apparatus. In addition to being efficiently and continuously performed, it is possible to perform these controls strictly, so that the reduction of man-hours and the improvement of yield are remarkable as compared with the conventional wet method.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a magnetic recording medium of the present invention in which a second protective layer is a fluorinated amorphous carbon film.

FIG. 2 is a schematic cross-sectional view of a magnetic recording medium of the present invention in which a protective film is a thin film in which diamond microcrystals and fluorinated amorphous carbon coexist.

FIG. 3 is a schematic cross-sectional view of the magnetic recording medium of the present invention in which the protective film is a two-layer film of diamond microcrystals and fluorinated amorphous carbon.

FIG. 4 is a diagram showing hardness and friction coefficient for each content ratio of a raw material monomer and fluorine according to a thin film forming method.

FIG. 5 is a schematic cross-sectional view of a conventional magnetic recording medium in which a second protective layer is formed by a wet method.

[Explanation of symbols]

 1 substrate 2 plating layer 3 magnetic recording medium layer 4 first layer protective film 5 second layer protective film 6 second layer protective film 7 protective film 8 first layer protective film 9 second layer protective film

Claims (4)

[Claims] 1. A magnetic recording medium having a substrate, a magnetic recording medium layer on the substrate, and a protective film on the magnetic recording medium layer, wherein the protective film is an amorphous carbon thin film and fluorinated thereon. A magnetic recording medium comprising an amorphous carbon thin film. 2. A magnetic recording medium having a substrate, a magnetic recording medium layer on the substrate, and a protective film on the magnetic recording medium layer, wherein the protective film coexists with diamond microcrystals and fluorinated amorphous carbon. A magnetic recording medium characterized by being a thin film. 3. The magnetic recording medium according to claim 2, wherein the protective film is formed by laminating a plurality of thin films having different mixing ratios of diamond microcrystals and fluorinated amorphous carbon. Medium. 4. The magnetic recording medium according to claim 2 or 3, wherein the protective film is formed by an ECR plasma CVD method.