JPH0758545B2 - Method of manufacturing thin film magnetic recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a thin film magnetic recording medium having a magnetic layer made of a ferromagnetic metal thin film, which is used in a fixed magnetic disk device.

[Prior Art] A thin-film magnetic recording medium usually has a layer structure in which a non-magnetic metal underlayer, a magnetic layer, a protective layer, and a lubricating layer are sequentially laminated in a thin film on a non-magnetic substrate. As the non-magnetic substrate, an Al alloy substrate on which a Ni-P alloy layer is formed by electroless plating is used. The Ni-P alloy layer is provided to reinforce the mechanical strength of each thin film laminated thereon. The non-magnetic metal underlayer is provided to enhance the magnetic properties, and generally Cr is used and is formed by the sputtering method. The magnetic layer generally uses a Co-based alloy, for example, a Co-Ni alloy, and is formed by the sputtering method. The protective layer is provided to improve corrosion resistance and abrasion resistance, and generally amorphous carbon (a-C) or SiO ₂ is used and is formed by a sputtering method or the like. The lubricating layer is provided to enhance abrasion resistance and is formed by applying a liquid lubricant or a solid lubricant.

[Problems to be Solved by the Invention]

As a method of applying the above-mentioned liquid lubricant as a lubricating layer, there are a dip method, a spin coat method, a spray buff method and the like. However, no matter which method is used, a simple coating does not provide a sufficiently satisfactory lubricating layer, and contact start / stop ( Below, CS
The friction coefficient increases in the S) test and the adsorption force test,
Even in actual use, there were problems that the coefficient of friction increased due to repeated CSS and that the magnetic head was attracted to the medium surface.

The present invention solves the above-mentioned problems and makes it possible for practical use.
An object of the present invention is to provide a highly reliable and highly reliable thin-film magnetic recording medium manufacturing method in which the friction coefficient does not increase even when CSS is repeated and the magnetic head is hardly attracted to the medium surface. .

[Means for Solving the Problems]

In order to achieve the above object, the present invention forms a protective layer on a magnetic layer made of a ferromagnetic metal thin film, applies a liquid lubricant on the protective layer, and presses a cloth on the surface to buff. In the method of manufacturing a thin film magnetic recording medium to form a lubricating layer by performing, the protective layer is made of amorphous carbon, the lubricating layer is made of fluorocarbon lubricant, the surface pressure when performing the buffing is 2kg / cm ² or more, 3 kg / c
It is characterized by being less than m ² .

[Action]

When the fluorocarbon liquid lubricant is applied on the protective layer, as shown in the partial sectional view of the main part of the medium of FIG.
It seems that the lubricant 2 is attached to the surface of the protective layer 1 in an island shape. Such pressing fabrics coated surface against with 2 kg / cm ² or more, by performing the buff 3 kg / cm ² or less of surface pressure, first
As shown in the partial cross-sectional view of the main part of the medium in the figure, the lubricant 2 flows from the thick film portion to the thin film portion so as to correct the film thickness variation, and lubricates as a continuous film having a uniform film thickness on the protective layer 1. A lubricant layer made of the agent 2 can be formed. By using such a continuous film as the lubricating layer, the friction coefficient in the CSS test and the attraction test can be reduced, and the attraction of the magnetic head to the medium can be prevented.

〔Example〕

Ni-P by electroless plating on a disk-shaped substrate made of Al alloy
An alloy layer is formed, and after its surface is mirror-finished or textured, a non-magnetic metal underlayer made of Cr, a magnetic layer made of Co-Ni alloy, and a protective layer made of a-C are formed on the surface by sputtering. Were sequentially laminated, and a solvent containing 0.4% by weight of a fluorocarbon liquid lubricant was applied thereon by a dip method. A medium having a lubricating layer of a uniform continuous film of liquid lubricant by pressing a cloth (for example, a wiping cloth) against the lubricant application surface while rotating this disk at 100 rpm to buff Was produced. The surface pressure of pressing the cloth against the medium surface is 1.0, 1.5, 2.0, 2.
The adsorption force test was performed on the medium prepared by changing the weight to 5 kg / cm ² . In the adsorption test, the medium and the magnetic head are kept in contact with each other and left for 1 day in an atmosphere of temperature 33 ° C and relative humidity 80%, and then the static friction coefficient is measured to satisfy a predetermined standard value, for example 0.4 or less. The quality was judged by whether or not to do it. As a result, it is judged as valid surface pressure 2.0,2.5kg / cm ² as shown in FIG. 3, hardly occurs adsorbed at a surface pressure of 2.0 kg / cm ² or more, it can be seen that the coefficient of static friction is less good . However, if the surface pressure exceeds 3.0 kg / cm ² , there is a problem in that the lubricant may separate during buffing or the cloth may be fused. Therefore, the surface pressure when buffing is 2.0 kg / cm ² or more 3.0
It is necessary to be in the range of kg / cm ² or less, and more preferably in the range of 2.0 kg / cm ² or more and 2.5 kg / cm ² or less.

Also, with a medium produced by buffing at a surface pressure of 2.5 kg / cm ² ,
CSS tests were performed on media that were not buffed. The relationship between CSS cycle and coefficient of friction is shown in the diagram in Fig. 4. It is clear from Fig. 4 that the buffed medium does not increase in friction coefficient even after repeated CSS, and is superior to the medium without buffing.

The relationship between the surface roughness of the medium and the film thickness of the lubricating layer made of the liquid lubricant was examined for the medium prepared by buffing and the medium prepared in the same manner but not subjected to buffing. The measurement results are shown in the diagram of FIG. Here, the surface roughness is 1 from the depth of 10% of the relative load curve of the Abbott of the surface roughness of the medium.
The difference is calculated by subtracting the depth of%. Since the thickness of the lubricating layer is thicker in the buffed medium than in the non-buffed medium, and the larger the numerical value indicating the surface roughness, the larger the difference between the two thicknesses. Before the buff, the liquid lubricant adhered in an island shape as shown in Fig. 2, but by buffing it became a continuous film with a uniform film thickness as shown in Fig. 1. Conceivable.

〔The invention's effect〕

According to the present invention as described above, a fluorocarbon-based liquid lubricant was applied to the protective layer made of amorphous carbon, by pressing a cloth 2 kg / cm ² or more on the surface thereof, 3 kg / cm ² or less surface pressure Since the lubricating layer is formed by performing buffing, the film thickness of the lubricating layer of the thin film magnetic recording medium manufactured by the present invention can be made uniform to prevent adsorption of the magnetic head and enhance CSS durability. it can.

[Brief description of drawings]

FIG. 1 is a partial sectional view of an essential part of a lubricating layer of a medium according to a manufacturing method for buffing according to the present invention, FIG. 2 is a partial sectional view of an essential part of a lubricating layer of a medium according to a conventional manufacturing method, and FIG. Fig. 4 is a diagram showing the relationship between the contact pressure of the cloth and the quality of the suction force test. Fig. 4 is a diagram showing the relationship between the CSS cycle and the coefficient of friction for media with and without the buffing process. FIG. 5 is a diagram showing the relationship between the surface roughness and the thickness of the lubricating layer for media with and without a buffing process. 1 ... Protective layer, 2 ... Liquid lubricant.

Claims (1)

[Claims] 1. A lubricating layer is formed by forming a protective layer on a magnetic layer made of a ferromagnetic metal thin film, applying a liquid lubricant on the protective layer, and pressing a cloth against the surface to buff the surface. In the method for producing a thin film magnetic recording medium, the protective layer is made of amorphous carbon, the lubricating layer is made of a fluorocarbon lubricant, and the surface pressure when performing the buffing is 2 kg / cm ² or more, 3 kg / cm ² A method of manufacturing a thin film magnetic recording medium, characterized in that: