JPH0869620A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE: To produce a magnetic recording medium having a low error rate and capable of reducing the height of floating of a recording reproducing head for stable running. CONSTITUTION: An abrasive tape is pressed against the surface of a nonmagnetic subsfrate while rotating the substrate and the surface of the substrate is textured by polishing while feeding a grinding liq. at >=40 deg.C to a part near the surface of the substrate brought into contact with the abrasive tape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magnetic recording medium such as a magnetic disk used in a fixed magnetic disk device as an external storage device of an information processing device.

[0002]

2. Description of the Related Art In recent years, fixed magnetic disk devices have been widely used as external storage devices for information processing devices such as computers. In a magnetic disk as a magnetic recording medium mounted in this fixed magnetic disk device, a Ni-P film is generally formed on the surface of a substrate made of a disk-shaped non-magnetic material such as aluminum alloy or glass by electroless plating. A non-magnetic metal underlayer made of Cr, a thin-film magnetic layer made of Co alloy, and a protective film made of amorphous carbon are sequentially deposited on a non-magnetic substrate by a sputtering method, and a lubricating layer is formed by applying a liquid lubricant thereon. Is formed.

In manufacturing such a magnetic recording medium,
The surface of the non-magnetic substrate is mirror-polished and washed, and thereafter, in order to improve the durability and magnetic characteristics of the medium, it is subjected to texturing for forming grooves in the substantially circumferential direction of the disk. Such texturing usually takes the substrate several tens of rpm.
While rotating in to several hundred rpm to polish by pressing a polishing tape to the surface pressing at pressure of ^{1kg / cm 2 ~4kg / cm 2} , it has been made by the so-called tape textured. At this time, the grinding fluid is caused to flow near the contact portion between the surface of the substrate and the polishing tape, but conventionally, the temperature of the grinding fluid is not particularly controlled and is almost equal to the temperature of the processing environment.
It was about 0 ° C to 25 ° C.

In addition, the texture processing is performed in two steps, the above-mentioned tape texture processing is performed as the first step, and then the second step is that the abrasive particles are dispersed and suspended in the grinding fluid on the flocking tape pressed against the rotating substrate surface. A so-called slurry texture is also applied, in which the slurry is dropped and polished.

[0005]

In the above-mentioned tape texturing, as a polishing tape, conventionally, a film made of a polyester resin is generally adhered with abrasive grains mixed with a polyester resin adhesive. Different abrasive tapes have been used. However, the film and the adhesive are relatively hard, and when abrasive particles that are particularly protruding are present on the surface of the polishing tape, deep grooves are formed on the surface of the substrate during polishing, and a substrate having such an abnormally deep groove was used. The medium has a problem that defects are generated due to the grooves when recording information. Further, the burrs on the surface of the substrate, which are generated when the protruding abrasive grains are deeply dug up, hinder the stable floating operation of the recording / reproducing head.

The present invention has been made in view of the above points, and forms deep grooves or burrs that cause problems on the surface of a substrate even when abrasive particles that are particularly protruding are present on the surface of the polishing tape. An object of the present invention is to provide a method for manufacturing a magnetic recording medium that can be subjected to tape texture processing so as not to do so.

[0007]

According to the present invention, the above-mentioned problems are solved in a method of manufacturing a magnetic recording medium including a texture processing step of polishing a non-magnetic substrate while rotating it by pressing a polishing tape against the surface of the non-magnetic substrate. The temperature of the grinding liquid flowing on the contact surface between the non-magnetic substrate surface and the polishing tape is 40
It is solved by performing the texture processing at a temperature of ℃ or higher.

In this case, the non-magnetic substrate may be formed by forming a Ni-P film on the surface of the non-magnetic substrate by electroless plating, and the non-magnetic substrate may be made of aluminum alloy or glass. Good.

[0009]

When the tape texture of the surface of the non-magnetic substrate is used, the base film and the adhesive of the polishing tape are softened by using the grinding liquid whose temperature is raised. When it is pressed against, it does not sink to the base film side to form a deep groove on the surface of the substrate, and it is possible to prevent the occurrence of burrs.

When the temperature of the grinding liquid is 40 ° C. or higher, an abnormally deep groove is not formed and an error at the time of recording information due to the deep groove is not generated, which is preferable. But,
The grinding fluid is mainly composed of mineral oil, to which surfactants, organic amines, water, etc. are added, and it is not preferable to raise the temperature too high. It is desirable that the temperature is about 60 ° C or less, and the upper limit does not exceed about 70 ° C. Better.

[0011]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to the following examples unless the gist thereof is impaired. Example 1 A Ni-P film having a film thickness of 12 μm is formed on the surface of a disk-shaped aluminum alloy substrate (outer diameter 95 mm) for a 3.5-inch magnetic disk by an electroless plating method to obtain a non-magnetic substrate. After the surface of this substrate is mirror-polished and washed, the substrate is
While rotating at 00 rpm, the average grain size 2 on the surface
1.5k of polishing tape of white alundum abrasive grain of μm
It is pressed at a pressure of g / cm ² and polished while flowing a grinding liquid in the vicinity of the contact portion to perform the first-step tape texture processing. Subsequently, a second stage of slurry texture processing is carried out in which a slurry in which white alundum abrasive grains having an average abrasive grain size of 1 μm are dispersed and suspended in a grinding fluid is dropped onto a flocking tape pressed against the surface of a rotating substrate, while being dropped. .

In the tape texture processing of the first stage, as a grinding liquid, a commercially available general grinding liquid (usually mineral oil containing a surfactant, an organic amine, a chlorine-based extreme pressure agent, an antiseptic agent,
A solution obtained by diluting an anticorrosive agent, water and the like) 30 times with pure water was heated to various temperatures and used. The depth R _V of the groove on the surface of the substrate after texture processing was measured with a surface roughness meter (Model ET-30K) manufactured by Kosaka Laboratory, and the relationship with the grinding liquid temperature was investigated. The result is shown in FIG. In FIG. 1, the horizontal axis represents the temperature of the grinding liquid, and the vertical axis represents the maximum groove depth R _V at each grinding liquid temperature. As can be seen in FIG. 1, the higher the temperature of the grinding fluid, the smaller the maximum groove depth R _V.

After precisely cleaning the textured substrate as described above, a Cr layer (film thickness of about 100 nm) as a non-magnetic metal underlayer and a Co alloy layer (film) as a nonmagnetic metal underlayer are sputtered thereon. A thickness of about 50 nm) and a carbon film as a protective film (thickness of about 15 nm) are sequentially formed.
A perfluoropolyether-based liquid lubricant was applied thereon to a thickness of about 2 nm to form a lubricating layer, and a magnetic recording medium was produced.

The number of errors was checked for each magnetic recording medium manufactured in this way. The result is shown in FIG.
As can be seen in Fig. 2, the number of errors decreases as the temperature of the grinding fluid during the tape texture processing of the first step increases, reaching 40 ° C.
It was not detected above. Furthermore, when the minimum stable flying height of the recording / reproducing head was evaluated, as shown in FIG. 3, it decreased as the grinding liquid temperature increased.

[0015]

According to the present invention, in the tape texture processing performed by using the polishing tape on the surface of the non-magnetic substrate, the temperature of the grinding liquid is set to 40 ° C. or more so that the polishing tape is particularly projected on the surface. Even if there are abrasive grains, it is possible to perform texture processing that does not form deep grooves that would cause problems on the substrate surface, reduce the number of errors, and lower the stable flying height of the recording / reproducing head. It is possible to obtain a magnetic recording medium capable of achieving the above.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the temperature of the grinding fluid during tape texture processing and the R _V of the substrate surface after texture.

FIG. 2 is a diagram showing the relationship between the temperature of the grinding fluid and the number of errors in the magnetic recording medium during tape texture processing.

FIG. 3 is a diagram showing the relationship between the temperature of the grinding fluid and the minimum stable flying height of the recording / reproducing head during tape texture processing.

Claims (4)

[Claims] 1. A method for producing a magnetic recording medium, comprising a texture processing step of polishing a non-magnetic substrate by pressing a polishing tape against the surface while rotating the non-magnetic substrate, and flowing to the contact surface between the surface of the non-magnetic substrate and the polishing tape. The temperature of the grinding fluid is 4
A method of manufacturing a magnetic recording medium, which comprises performing texture processing at 0 ° C. or higher. 2. The method for producing a magnetic recording medium according to claim 1, wherein the non-magnetic substrate is formed by forming a Ni-P film on the surface of the non-magnetic substrate by electroless plating. 3. The method of manufacturing a magnetic recording medium according to claim 2, wherein the material of the non-magnetic substrate is an aluminum alloy. 4. The method of manufacturing a magnetic recording medium according to claim 2, wherein the material of the non-magnetic substrate is glass.