JPH064861A - Method of manufacturing thin film magnetic disk - Google Patents

Abstract

(57) [Summary] [Purpose] Do not texture the plane board,
Magnetic anisotropy is given by surface treatment in the circumferential direction. [Structure] N in the surface treatment step (e) before the film formation step (g)
The surface of the i-P substrate 8 is wetted with the hydrophilic surface treatment liquid 7 having an etching action, and the treatment tape 9 is pressed by the contact roller 10 to rotate the substrate 8 for surface treatment. [Effect] Since only the surface treatment is required without using a working fluid containing abrasive grains or polishing powder, cleaning after the treatment is simplified, magnetic anisotropy is provided, and the flying characteristics of the head are improved.

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 thin film magnetic disk used as an external storage device such as an electronic computer or a workstation.

[0002]

2. Description of the Related Art A storage device using a magnetic recording medium such as a magnetic disk is widely used as an external storage device for a computer, a workstation, etc., and has a large capacity as the amount of information has increased in recent years. Are required. On the other hand, the shape of the apparatus itself is desired to be smaller and lighter, and in order to achieve both of them, it is essential to dramatically improve the recording density of the recording medium.

For example, in the manufacture of magnetic disks,
Before forming the magnetic film in order to improve the magnetic characteristics, the substrate surface of the magnetic disk, or Ni-P plating, for example, which is previously provided as a base film on the substrate surface, is shown in a partially broken perspective view of FIG. Surface treatment processing (hereinafter abbreviated as texturing) is performed in the circumferential direction of a magnetic disk medium to leave processing marks in a substantially concentric shape.

Texturing is one of its advantages (1)
The effect of reducing the adsorption phenomenon between the magnetic head and the magnetic disk medium when the magnetic disk is stopped, and (2) by giving shape anisotropy to the magnetic film formed on the processed surface,
It has the effect of making the magnetic characteristics uniform in the circumferential direction.
However, on the other hand, since it is processed using abrasive grains such as diamond and alumina, burrs and protrusions are likely to occur on the substrate surface, which makes the flying characteristics of the magnetic head and the crystal growth of the magnetic medium uneven, However, there was a problem that magnetic properties such as coercive force could not be expected to improve.

Note that, as for those related to this kind of texturing, for example, JP-A-62-262227, JP-A-63-42019, JP-A-63-42027,
Publications such as JP-A-63-249933 are mentioned.

[0006]

SUMMARY OF THE INVENTION Therefore, the present invention has been made in view of the above situation, and an object thereof is to solve the problem of the conventional texturing technique. Without impairing the floating characteristics, and
It is an object of the present invention to provide a method for manufacturing a thin film magnetic disk having an improved substrate surface processing technique capable of improving magnetic characteristics.

[0007]

In order to achieve the above object, according to the present invention, the surface of a substrate plated with an underlayer Ni-P before the formation of a magnetic film or the like is treated with an abrasive-free surface treatment liquid and a surface treatment tape.
It is characterized by rubbing in a concentric circle with a bur (surface treatment). That is, more specifically, the above object is a method for manufacturing a thin film magnetic disk including a step of sequentially forming an underlayer film, a magnetic film, a protective film, and a lubricating film on a Ni-P plated substrate supporting a magnetic medium. In the method of manufacturing a thin-film magnetic disk, the step of surface-treating the surface of a Ni-P substrate with a surface treatment solution and a surface treatment tape is added as a pre-step of the film forming step.

As the surface treatment liquid, those containing alcohol or a hydrophilic treatment liquid such as a surfactant as a main component are preferable, and these may be used alone or in combination of both.

Examples of alcohols include polyhydric alcohols such as ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol and glycerin, or higher alcohols having an appropriate viscosity.
There is Le.

As the surfactant, for example, one containing a polyoxyethylene-based nonionic surfactant as a main component is preferable, and it is preferable to use one having an etching action because the effect of the surface treatment is further improved. Similarly, it is effective to add a component having an etching action to a treatment liquid of alcohols such as ethylene glycol.

For the surface-treated tape, it is preferable to use synthetic fibers such as aliphatic polyamide such as nylon, polyester, cellulose and the like.

[0012]

The plane substrate, which is the substrate of the magnetic disk, is a flat substrate macroscopically, but has microscopically small scratches on the surface microscopically. Therefore, magnetic anisotropy cannot be obtained even if a magnetic medium is formed on this substrate. However, when the surface treatment liquid is applied to the plane substrate and the tape is rubbed in the circumferential direction with the tape, the random scratches are eliminated, and fine streaks remain in the rubbed direction. Further favorable results can be obtained by allowing the surface treatment liquid to have etching treatment ability.

By thus performing the surface treatment in the circumferential direction, magnetic anisotropy appears in the circumferential direction in the magnetic medium formed on the surface of the magnetic medium. Since burrs and protrusions generated by cutting are not generated at all, the flying characteristics of the head are improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. <Embodiment 1> FIG. 1 is a process drawing showing an example of a manufacturing process of a thin film magnetic disk of the present invention, FIG. 2 is a partially cutaway perspective view showing the structure of a thin film magnetic disk, and FIG. 3 shows a surface treatment method. FIG. 4 is a perspective view schematically showing an apparatus to be realized, and FIG. 4 is a characteristic diagram showing magnetic characteristics of a substrate manufactured by the manufacturing process of the present invention.

As shown in FIG. 2, the structure of the thin-film magnetic disk is as follows: an aluminum alloy substrate 1 for supporting the magnetic medium, a Ni--P plated underlayer 2 for giving the substrate an appropriate hardness, and a magnetic anisotropic medium of the magnetic medium. It is composed of a base film 3 for imparting properties, a magnetic film 4, a protective film 5 for protecting the magnetic film from wear, and a lubricating film 6 for reducing the wear coefficient. However, in this embodiment, the Ni—P plating base film 2 of FIG. 2 is not textured.

The method of manufacturing the thin film magnetic disk of this embodiment will be described below with reference to the process chart of FIG. Process (a)
Then, the aluminum alloy substrate 1 is prepared as a disc substrate. In step (b), Ni-P plating 2 is applied to the substrate 1 by electroless plating to a thickness of 10 to 30 μm. In the step (c), the surface of the Ni-P plating 2 is mirror-polished using a working liquid containing abrasive grains, polishing powder and the like. The substrate surface is washed in step (d).

In step (e), a surface treatment is carried out in the circumferential direction with a surface treatment liquid and a treatment tape. This surface treatment method is a feature of the present invention, and FIG. 3 shows an example of an apparatus for realizing it. As the surface treatment method, as shown in FIG. 3A, the treatment liquid 7 is dropped between the substrate 8 and the treatment tape 9 which is rotationally moved orthogonally thereto, and the contact roll is used.
A method of rotating the substrate 8 while pressing it with a roller 10, as shown in FIG. 2B, spraying the treatment liquid 7 onto the substrate 8 and pressing the substrate 8 with a contact roller 10 in the same manner. There is a method of rotating the substrate, or the substrate 8 may be immersed in the treatment liquid.

The width of the contact roller 10 may be smaller than the radius of the substrate 8, the same width as the radius, or the same width as the diameter of the substrate 8. However, in this case, the width of the processing tape 9 needs to be the same as or wider than the width of the roller 10. By swinging the contact roller 10 and the processing tape 9, the substrate surface can be uniformly processed.

The pressing pressure of the tape 9 varies depending on the width, material, hardness, etc. of the roller 10, but normally 1 to 5 kgf is desirable. In this embodiment, for example, a 45 mm wide polyurethane roller is used. Was used at 2.5 kgf. The pressing pressure in this case needs to be at least 1 kgf. The rotation speed of the disk may be in the range of 100 to 1000 rpm, but in this embodiment, it is set to 600 rpm. The treatment time is several seconds to several minutes, and is selected depending on the composition of the treatment liquid and the type of treatment tape.

The treatment tape 9 is preferably made of a synthetic fiber such as polyamide such as nylon, polyester, or cellulose in a tape shape. The treatment liquid is preferably a hydrophilic treatment liquid in order to provide a sliding state between the substrate 8 and the treatment tape 9 and a treatment effect on the substrate surface. For example, polyhydric alcohols such as ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin, etc. as the main component of the treatment liquid, higher alcohols having appropriate viscosity, and further surfactants. Etc. are preferred. The main component of the surfactant is preferably a polyoxyethylene-based nonionic surfactant or the like. In the case of a surfactant, the effect of the surface treatment is further improved by using one having an etching action. Similarly, with respect to other processing liquids such as ethylene glycol, a liquid having an etching action may be added. Considering the cleaning [step (f)] after the surface treatment, the use of the surfactant for cleaning has an advantage that the process is simple because only the rinsing of the detergent is required. The substrate 8 thus obtained has a uniform surface state, and a thin film magnetic disk having good magnetic characteristics can be obtained in the subsequent steps.

In step (f), cleaning after the surface treatment is performed.
In step (g), a Cr underlayer film 3, a Co magnetic film 4, and a C protective film 5 having a predetermined thickness are sequentially formed on the substrate 8 by a sputtering method. In step (h), in order to remove dust and protrusions on the substrate during film formation, surface treatment is performed only with the tape 9 using the surface treatment apparatus shown in FIG. In this case, the processing liquid is not used. The lubricant 6 is applied in the step (i). The final inspection is performed in step (j). The magnetic disk of FIG. 2 was manufactured through the above steps.

FIG. 4 shows the substrate 8 surface-treated in the step (e).
9 shows the results of measuring the magnetic anisotropy of the magnetic disk having the Cr underlayer film, the Co magnetic film, and the C protective film formed by the sputtering method in the step (g). The vertical axis represents the coercive force Hc (θ) in the circumferential direction and the coercive force Hc (R) in the radial direction.
The ratio of When Hc (θ / R) is 1, there is no magnetic anisotropy, and the larger this value is, the more magnetic anisotropy is attached, indicating that the magnetic characteristics are good. As a result, it can be seen that the surface treatment of this example has markedly higher magnetic anisotropy than the untreated (plain substrate) substrate prepared for comparison. The surface treatment A according to this example uses propylene glycol as the main component of the treatment liquid, and the treatment liquid of surface treatment B also uses the detergent containing polyoxyethylene-based surfactant as the main component. Are shown respectively.

<Embodiment 2> Since the conventional texturing is performed by using abrasive grains such as diamond and alumina, burrs and protrusions are apt to occur on the substrate surface, which causes levitation characteristics and magnetic properties of the magnetic head. The crystal growth of the medium became non-uniform, and we could not expect improvement in magnetic properties such as coercive force.
Even in such a case, if the surface treatment step of the present invention is adopted after texture processing, the surface condition is modified and the magnetic properties are improved. That is, in this example, the step (e) of Example 1 is performed in two steps. First, the surface of the Ni-P plating 2 is textured by a known method,
Then, the same surface treatment as in step (e) of Example 1 is performed.

Although two embodiments have been described above as concrete examples of the present invention, comparing the first embodiment with the second embodiment, the feature of the present invention is that the texturing is not always necessary. Therefore, in practice, it is preferable to carry out the first embodiment rather than the second embodiment.

[0025]

As described above, according to the present invention, since processing using abrasive grains is not performed unlike texture processing,
Since the substrate surface is treated by simply rubbing it with a treatment liquid and a treatment tape, the conventional problems can be solved and the intended purpose can be achieved. That is,
(1) No burrs or protrusions are generated, (2) Cleanability after treatment is good because no abrasive grains are used, and (3) Only surface treatment is required without using a machining liquid containing abrasive grains or polishing powder. Cleaning after the treatment is simplified, and (4) magnetic anisotropy is added, and the flying characteristics of the head are improved.

[Brief description of drawings]

FIG. 1 is a manufacturing process diagram of a thin-film magnetic disk showing an embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view showing the structure of a thin film magnetic disk.

FIG. 3 is a perspective view schematically showing an example of an apparatus that also realizes the surface treatment method.

FIG. 4 is a characteristic diagram showing a holding force ratio Hc (θ / R) in a circumferential direction (θ) and a radial direction (R) as magnetic characteristics.

[Explanation of symbols]

1 ... Aluminum substrate, 2 ... Ni-P
Base film, 3 ... Base film, 4 ...
Magnetic film, 5 ... Protective film, 6 ...
Lubrication film, 7 ... Treatment liquid, 8 ...
Ni-P substrate, 9 ... Processing tape,
10 ... Contact roller.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriyuki Takeo 2880 Kozu, Odawara, Kanagawa Hitachi Odawara Factory (72) Inventor Masahiro Watanabe 292 Yoshida-cho, Totsuka-ku, Yokohama, Kanagawa Inside the technical laboratory

Claims (10)

[Claims] 1. A method of manufacturing a thin film magnetic disk, comprising a step of sequentially forming a base film, a magnetic film, a protective film, and a lubricating film on a Ni-P plated substrate supporting a magnetic medium, before the film forming step. A method of manufacturing a thin-film magnetic disk, which additionally comprises a step of surface-treating the surface of a Ni-P substrate using a surface-treating liquid and a surface-treating tape. 2. A step of surface-treating a surface of a Ni-P substrate using a surface-treating liquid and a surface-treating tape, which is a pre-step of the film-forming step, in which the surface-treating is performed in a circumferential direction of the substrate surface. 2. The method for manufacturing a thin film magnetic disk according to claim 1, wherein the step is a step of providing magnetic anisotropy in the circumferential direction. 3. A step of surface-treating a surface of a Ni-P substrate using a surface treatment solution and a surface treatment tape, which is a pre-step of the film forming step, by applying a treatment solution to the surface treatment tape. 2. The method of manufacturing a thin-film magnetic disk according to claim 1, which comprises a surface treatment step of rubbing the substrate surface in a circumferential direction. 4. The method for manufacturing a thin film magnetic disk according to claim 1, wherein the surface treatment liquid is a hydrophilic liquid. 5. A method of manufacturing a thin film magnetic disk according to claim 1, wherein the surface treatment liquid is provided with an etching function. 6. The surface treatment liquid is composed mainly of at least one of alcohols and surfactants.
Alternatively, the method for manufacturing the thin film magnetic disk according to the item 5. 7. The method of manufacturing a thin film magnetic disk according to claim 6, wherein the alcohol is composed of at least one of a polyhydric alcohol and a higher alcohol. 8. The method of manufacturing a thin film magnetic disk according to claim 6, wherein the surfactant is a polyoxyethylene-based nonionic surfactant. 9. The method of manufacturing a thin film magnetic disk according to claim 1, wherein the surface-treated tape is made of synthetic fiber. 10. A method of manufacturing a thin film magnetic disk according to claim 9, wherein the synthetic fiber is composed of at least one fiber selected from the group consisting of polyamide, polyester and cellulose.