JPH08221745A - Production of thin-film magnetic recording medium - Google Patents

Abstract

PURPOSE: To suppress the generation of scratches and burrs by removing the foreign matter and dust included or adhered in the production process of a tape-like holder holding a polishing agent in a substrate texture treatment. CONSTITUTION: While the tape-like holder 3 on which a polishing material is dropped, is evenly pressed via a contact rubber roller 2 in the radial direction of a rotating substrate 1, the holder is sent at a specified speed to provide a relative speed difference between the substrate 1 and the tape-like holder 3, thereby, texture shapes consisting of fine and uniform grooves and ruggedness are formed in the circumferential direction of the substrate 1. A dust removing unit 7 is installed in the position just before the tape-like holder 3 acts. This dust removing unit 7 blows ultrasonic pressure air toward the surface of the tape-like holder 3, thereby peeling and vacuum (vacuum suction) removing the foreign matter and dust included or adhered on the surface in the production process from the surface of the tape-like holder 3. The generation of the scratches and burrs on the texture surface of the substrate is suppressed, thereby, the floating characteristic and error characteristic of the magnetic head on the magnetic recording medium surface are improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to unevenness (hereinafter referred to as "texture") having a predetermined surface roughness on the surface of a Ni-P plated substrate in the manufacturing process of a thin film magnetic recording medium. The present invention relates to a texturing process for forming, and particularly to a texturing technique suitable for suppressing texture defects (abnormal irregularities) that hinder the floating property and error characteristics.

[0002]

2. Description of the Related Art A thin film magnetic recording medium is a non-magnetic substrate made of an aluminum alloy, which is electrolessly plated with Ni-P, and the surface of the plating is mirror-polished. As a means for obtaining uniformity, a magnetic film or the like is formed by sputtering on the surface of the substrate in the circumferential direction and then washed to form a magnetic film. Here, the texture process is as described in JP-A-1-267834.
A slurry containing abrasive grains having a predetermined grain size is dropped onto a tape-shaped holder having elasticity and uniformly pressed in the radial direction of the rotating substrate surface through a contact rubber roller,
A texture shape composed of fine and uniform grooves and irregularities in the circumferential direction on the surface of the substrate by causing the relative speed difference between the substrate and the tape-shaped holder to be sent by feeding the tape-shaped holder at a predetermined speed. By forming a base film, a magnetic film, and a protective film on the textured surface by a sputtering method, the adhesion of the magnetic head is prevented and the uniformity of magnetic orientation is optimized. However, in order to meet the demand for high density recording of the magnetic recording medium, it is necessary to lower the flying height of the magnetic head, and the center line average roughness Ra 5 nm to 8 nm of the conventional substrate texture shape prevents the magnetic head from sticking and lowering. It has become very difficult to achieve both levitation. As a means for dealing with this, as described in JP-A-3-252922, the conventional substrate texture is limited to the purpose of obtaining the magnetic orientation uniformity during film formation, and the magnetic head is protected from sticking prevention and low flying height. Methods have been introduced to achieve this by forming controlled hills on the membrane. Next, regarding the relationship between the texture shape and the magnetic orientation uniformity, Japanese Patent Application Laid-Open No. 5-181015.
As described in Japanese Patent Publication No. JP-A-2004-115, by making fine texture marks in the circumferential direction of the substrate, the range of the center line average surface roughness Ra of the substrate surface is 0.5 nm or more and 5 nm or less, and
Ratio of maximum height Rmax of medium surface to Ra Rmax / Ra
It is said that the range of 10 to 30 is desirable. Here, the definitions of “center line average roughness” and “maximum height” are in accordance with Japanese Industrial Standards (JIS-B0610). From the above viewpoints, it is more effective for the surface shape of the substrate texture to be finely smoothed as much as possible in order to reduce the flying height of the magnetic head, and the surface roughness of the substrate is about ⅓ of the centerline average roughness Ra of the conventional one. Precision has come to be required. For this required accuracy, as described in JP-A-5-79355, as shown in Japanese Patent Laid-Open No. 5-79355, the abrasive grain size used for texturing is reduced, the fiber diameter of the tape-shaped holder is reduced, and This was achieved by optimizing the processing conditions.

[0003]

In the above-mentioned prior art, no consideration has been given to texture defects such as "scratch" and "burr" which hinder the floating property and error characteristics. When the scratches and burrs are analyzed with a surface roughness measuring machine, the Rmax / Ra ratio of the normal part is in the range of 5 or more and 10 or less, while the scratches or burrs part has the Rmax / Ra ratio of 20 or more. The scratches and burrs are the base film,
A large number of enlarged protrusions are formed on the surface of the magnetic recording medium, which causes abnormal growth when the magnetic film is formed. Next, when the projections are removed by a tape burnishing or a head burnishing, the size of the projections damages the magnetic medium and deteriorates the error characteristics. The same is true when the magnetic head is levitated, and both are damaged by the collision with the residual protrusion that cannot be removed. As described above, scratches and burrs that occur during texture have a great influence on the quality of the final product, which is a serious defect. Therefore, an object of the present invention is to form a textured shape that is less likely to cause scratches and burrs, and achieve a ratio of Rmax / Ra of 5 or more and 10 or less with respect to the entire textured surface of the substrate, thereby improving the quality of the final product. It is an object of the present invention to provide a method of manufacturing a magnetic recording medium that realizes stabilization of characteristics.

[0004]

Means for Solving the Problems In order to achieve the above object, the means of the present invention is to hold a slurry containing abrasive grains having a predetermined grain size in a tape shape having elasticity in a texturing step. It is dropped on the body and uniformly pressed in the radial direction of the rotating substrate surface via a contact rubber roller, and the tape-shaped holding member is fed at a predetermined speed, and the rotating substrate and the tape-shaped holding member are fed. By providing a relative speed difference, a dust removing function is added to a position immediately before the action of the tape-shaped holder when forming a texture shape consisting of fine and uniform grooves and irregularities in the circumferential direction on the substrate. , Mixed in the manufacturing process of the tape-shaped holder,
Alternatively, it removes foreign matter or dust that adheres to suppress the generation of scratches and burrs. Further, when the texture shape is obtained by using a wrapping tape instead of the tape-shaped holding body, the above object can be achieved in the same manner.

[0005]

[Function] As the tape-shaped holder, a type in which nylon pile (φ15um × 450um) is statically flocked to the base cloth, or ultrafine fibers composed of polyester and nylon (thickness of the original thread is 1 to 5um) The braided type is used. Usually, such members are clean
It is used in the form of a sheet for wiping inside the room and for wiping electronic parts. With dust-free cleaning compatible with Class 100, foreign matter and dust mixed in or adhering during the manufacturing process are removed to clean it. It is generally packaged.

However, when it is used as a tape-shaped holder, it is difficult to adopt the above dust-free cleaning. That is, when the tape-shaped holder is subjected to the dust-free cleaning treatment, the holder surface becomes wrinkled, and when the tape is textured in this state, unevenness of the texture occurs on the substrate surface. . Therefore, in the present invention, foreign matter or dust that is mixed or attached during the manufacturing process of the tape-shaped holder is removed at a position immediately before the texture action, so that the generation of scratches or burrs due to the foreign matter or dust can be suppressed.

[0007]

EXAMPLE An example of the present invention will be described below with reference to FIG. Substrate 1 is electroless plating of Ni-P on a non-magnetic disc of 3.5 inch aluminum alloy, both surfaces of the plating surface are polished, and center line average roughness Ra is 2.5 nm.
It is finished to the mirror surface. The inner peripheral portion of this substrate 1 is fixed to a chuck portion (not shown) of a spindle and is rotated at a predetermined speed. Next, a slurry-type abrasive 4 having a predetermined particle size is provided on the tape-shaped holder 3 by air-pressure feeding from a supply tank (not shown in the figure) equipped with a stirring rotor so that three tufts / face are provided. -Dripping through the bub (only one is shown in the figure).
This tube uses Teflon having an inner diameter of 1 mm, and in order to prevent the agglomeration of the abrasive in the tube, it is constantly vibrated (not shown in the figure) by a vibrator. The tape-shaped holder 3 is uniformly pressed in the radial direction of the rotating substrate 1 via the contact rubber roller 2, and the tape-shaped holder 3 is fed by the pinch roller 6 at a predetermined constant speed. Board 1 and tape
By giving a relative speed difference to the cup-shaped holder 3, a textured shape including fine and uniform grooves and irregularities is formed in the circumferential direction of the substrate 1. The tape-shaped holder 3 is, for example,
Width: 35 mm, length: 45 m, ultra-fine fibers composed of polyester and nylon (thickness of raw thread 1-5 u
The braided type of m) is adopted and set in the supply reel 5.

Although not shown in the drawing, a take-up reel is provided after the pinch roller 6. Guide low
Las 12, 13, and 14 prevent the tape-shaped holding body 3 from meandering or turning over and stably travel. A dust removing unit 7 is installed on the upper side of the tape-shaped holding body 3 between the guide rollers 12 and 13 and has a function of removing foreign matter and dust that are mixed in or attached during the manufacturing process of the tape-shaped holding body 3. I am making it. The backup roller 8 adjusts the gap between the tape-shaped holder 3 and the dust removing unit 7.

Next, in the example of the dust removing unit 7 of FIG. 1, pressure head portions 8 and 9 mainly containing an ultrasonic generator are provided.
And a vacuum head unit 10 for sucking and removing dust. Ultrasonic pressure air is blown onto the surface of the tape-shaped holder 3 to remove foreign substances and dust that are mixed in or adhered from the surface of the tape-shaped holder 3 during the manufacturing process, and the vacuum (vacuum) It is a non-contact web cleaner system that removes by suction. The major feature of this method is that dust removal can be performed in the dry state, so that wrinkles cannot be wrinkled on the tape-shaped holder 3, and the air-knife effect and ultrasonic effect of the pressure air can be used to remove coarse dust to fine dust. The point is that the tape-shaped holding body 3 is released from the surface, rides on a high-speed air flow, and is effectively sucked and removed from the vacuum head.
This effect is the same when a flocked tape-shaped holder or a wrapping tape is used.

Next, FIG. 2 shows an example in which an adhesive tape 15 is used as the dust removing unit 7. In the case of this example, the dust removing unit 7 includes a sending portion 16 of the adhesive tape 15, a pressing portion 17,
The winding unit 18 is provided. The adhesive tape 15 is continuously delivered from the delivery portion 16, and the adhesive surface of the adhesive tape 15 is pressed against the surface of the tape-shaped holding body 3 by the pressing portion 17, so that the tape-shaped holding body 3 is pressed. Mixed from the surface in the manufacturing process,
Alternatively, it is a method in which foreign matter and dust that adhere are transferred and removed. The feature of this method is that the structure is simple. Although FIGS. 1 and 2 only show the display on one side of the substrate 1, the same function is provided for the opposite side, and texture processing can be performed on both sides simultaneously.

[0011]

According to the present invention, a texture shape with less scratches and burrs is formed on the surface of a substrate, and the ratio of Rmax / Ra is 5 or more and 10 or less with respect to the entire textured surface of the substrate. , The quality characteristics of the magnetic recording medium, especially the flying characteristics and error characteristics of the magnetic head are improved,
Stabilization can be realized.

[Brief description of drawings]

FIG. 1 is a schematic view of a system having a pressure head unit having a built-in ultrasonic generator and a vacuum head unit for sucking and removing dust as a dust removing unit in a texture processing unit of an embodiment according to the present invention.

FIG. 2 is a schematic view of a system in which an adhesive tape is used as a dust removing unit in the texture processing unit of the embodiment according to the present invention.

FIG. 3 is a graph showing a Rmax / Ra ratio of a textured surface formed by an example according to the present invention in comparison with a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 substrate, 2 contact roller, 3 tape-shaped holder, 4 abrasive, 5 supply reel, 6 pinch roller, 7 dust removing unit, 8, 9 pressure head section, 10 vacuum head section, 11 Backup Roll, 12, 13, 14 Guide Roller, 15 Adhesive Tape, 16 Feeding Part, 17 Pressing Part, 18 Winding Part

Claims (3)

[Claims] 1. A method for manufacturing a magnetic recording medium comprising a circumferential texture step on a Ni-P plated substrate surface on an aluminum disc, wherein the texture step is elastic tape-shaped holding. A polishing agent is dropped onto the body, and a dust removing function is provided at a position immediately before the action of the tape-shaped holding body when an uneven shape is formed in the circumferential direction due to the relative speed difference between the substrate and the tape-shaped holding body. A method of manufacturing a thin-film magnetic recording medium, which is characterized by being added. 2. A method of manufacturing a magnetic recording medium, comprising a circumferential texture step on a Ni-P plated substrate surface on an aluminum disk, wherein the texture step supplies a polishing liquid to a lapping tape. However, a thin film magnetic recording medium characterized by adding a dust removing function to a position immediately before the action of the lapping tape when forming a concavo-convex shape in the circumferential direction by the relative speed difference between the substrate and the lapping tape. Manufacturing method. 3. The method of manufacturing a thin film magnetic recording medium according to claim 1 or 2, wherein the texture shape having a ratio of substrate surface roughness Rmax to Ra within a range of 5 or more and 10 or less is formed. A method of manufacturing a thin film magnetic recording medium, comprising: