JPH0554375A - Lubricating film forming method and lubricating film forming apparatus for magnetic disk - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a method and an apparatus for forming a lubricating film provided as a surface layer of a magnetic disk, and an object thereof is to form a lubricating film that enables reliable and stable magnetic storage. To do. A magnetic disk substrate 10 coated with a lubricant 50 is placed in an atmosphere of an organic solvent vapor 61, and an organic solvent vapor 6
The excessive lubricant 50 is dissolved and removed by dew condensation and dropping of No. 1 to form a uniform and extremely thin lubricating film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for forming a lubricating film provided as a surface layer of a magnetic disk.

In a magnetic disk device, the gap (spacing) between the magnetic disk and the magnetic head slider is being miniaturized in order to increase the recording density. Along with this, it is desired to prevent head adsorption and head crash due to the lubricating film provided as the uppermost layer of the magnetic disk.

[0003]

2. Description of the Related Art Conventionally, as a method of forming a lubricating film, a method of applying a lubricant by using a method such as a dipping method, a spin coating method, or a vapor deposition method for dew condensation of a lubricant vapor, and After that, a method of wiping off excess lubricant with paper or cloth to reduce the film thickness has been used.

[0004]

Conventionally, there has been a problem that it is difficult to form an appropriate lubricating film in order to stabilize the mechanical operation of the magnetic disk device and ensure the reliability.

That is, in the conventional CSS (contact start stop) type magnetic disk drive,
The magnetic head slider (hereinafter referred to as “slider”) may adhere to the magnetic disk via the lubricating film, so-called head attraction occurs, which may hinder the rotation of the magnetic disk. Also, the lubricant scattered by the contact with the slider or the air flow is accumulated on the slider, and the slider collides with the lubricant mass that has fallen off on the magnetic disk and disturbs the flying posture, which damages the magnetic layer. There was a case where a so-called head crash occurred, in which the stored information was destroyed.

There is known a method of roughening the surface of a substrate (non-magnetic substrate) serving as a base body of a magnetic disk or a protective film covering the upper surface thereof in order to suppress head adsorption.
When this method is used, the effective spacing increases, which is disadvantageous in terms of high-density recording. The present invention has been made in view of the above problems, and an object thereof is to provide a method and an apparatus for forming a lubricating film that enables highly reliable and stable magnetic memory.

[0007]

In order to solve the above-mentioned problems, the method according to the invention of claim 1 is as follows, as shown in FIG.
The magnetic disk substrate 10 coated with the lubricant 50 is placed in the atmosphere of the organic solvent vapor 61, and the excess lubricant 50 is dissolved and removed by condensation and dropping of the organic solvent vapor 61.

In the method according to the second aspect of the present invention, before the magnetic disk substrate 10 is placed in the atmosphere of the organic solvent vapor 61, the surface to be coated with the lubricant 50 is activated for surface activation. Add friction treatment.

In the method according to the third aspect of the present invention, the organic solvent vapor 61 is cooled while the magnetic disk substrate 10 is cooled.
Place in the atmosphere. The device according to the invention of claim 4 is
Inlet 9 for magnetic disk substrate 10 coated with lubricant 50
0A, a chamber 90 containing an organic solvent vapor 61 for partially dissolving and removing the lubricant 50, and a cooling means for condensing the organic solvent vapor 61 in order to suppress the outflow from the carry-in port 90A. And 93.

[0010]

When the magnetic disk substrate 10 coated with the lubricant 50 is carried into the chamber 90 from the carry-in port 90A and placed in the atmosphere of the organic solvent vapor 61, the organic solvent vapor 61 is condensed on the surface of the lubricant 50. It is dripped, whereby the lubricant 50 is dissolved from the surface layer and gradually removed. At this time, by cooling the magnetic disk substrate 10, dew condensation is speeded up and the efficiency of dissolving and removing the excess lubricant 50 is increased.

As the film thickness of the lubricant 50 decreases, the adhesive force to the surface to be coated becomes stronger. Therefore, when the film thickness decreases to a film thickness of about a monomolecular film, the dissolution and removal naturally stops. That is, an extremely thin uniform lubricating film can be easily formed.

When a friction treatment is performed to rub the surface to be coated before or after the coating of the lubricant 50, the surface of the surface to be coated is hardened to improve the adhesion of the lubricating film. Therefore, the phenomenon in which the lubricant 50 is pushed away when the slider slides and the lubricant film is partially thinned (or disappeared) hardly occurs, and the lubricity is improved. It should be noted that the organic solvent vapor 61 is introduced into the carry-in port 90.
It is condensed by the cooling means 93 in the vicinity of A, whereby the outflow of the organic solvent vapor 61 from the chamber 90 is suppressed.

[0013]

2 (a) and 2 (b) are views showing the structure of a magnetic disk 1 according to the present invention. FIG. 2A is a partially cutaway perspective view showing the external appearance, and FIG. 2B is an enlarged cross-sectional view of an essential part showing an AA portion surrounded by a chain line in FIG. 2A.

The magnetic disk 1 is an annular non-magnetic substrate 1.
1, a magnetic disk substrate 10 including an underlayer 12, a magnetic film 13, and a protective film 14, and a lubricating film 1 covering the upper surface thereof.
It is composed of 5 and. The non-magnetic substrate 11 is, for example, an alumite surface-treated aluminum substrate, and the underlayer 12 is formed of a plated film of nickel and phosphorus. Further, the magnetic film 13 is made of iron oxide such as γ-Fe ₂ O ₃ , and the protective film 14 is made of a hard carbon film having a thickness of about 200Å.

As will be described later, the lubricating film 15 utilizes the coating process of the lubricant on the magnetic disk substrate 10 and the condensation and dripping phenomenon of the organic solvent vapor by exposing the magnetic disk substrate 10 to the organic solvent vapor. It is formed by a series of processes including a process of removing excess lubricant.

FIG. 1 shows a lubricating film forming apparatus 100 according to the present invention.
It is a figure which shows the structure of the principal part of this typically. The lubricant film forming apparatus 100 includes a lubricant tank 70 for storing the lubricant 50, a solvent tank 80 for storing the organic solvent 60B, a chamber 90 for storing the organic solvent vapor 61, and the like, and serves as a work (magnetic disk being manufactured). The magnetic disk substrate 10 is conveyed along the route R, and the respective processes described below for forming the lubricating film 15 are sequentially and automatically performed.

A liquid tank portion 90C for accumulating the organic solvent 60 is provided under the chamber 90, and the organic solvent 60 for generating the organic solvent vapor 61 is formed at the bottom of the liquid tank portion 90C.
A heating means 96 for heating the is provided.

Further, the chamber 90 has a carry-in port 90A and a carry-out port 90B which are always open at positions corresponding to the route R.
And a window 90C for inspection and cleaning, and cooling means 93, 94 such as a cooling pipe for condensing the organic solvent vapor 61 in order to suppress the outflow to the outside in the vicinity of these openings. , 95 are assembled.

Lubricating film forming apparatus 1 configured as described above
In forming the lubricating film 15 by using No. 00, first, the magnetic disk substrate 10 is immersed in a liquid lubricant 50 that fills the lubricant tank 70 while being supported by a moving unit (not shown), and then slowly pulled up. Be done. As a result, the lubricant 50 is applied to the surface of the magnetic disk substrate 10 (the upper surface of the protective film 14) in the form of a relatively thick film.

Subsequently, the magnetic disk substrate 10 is immersed in the organic solvent 60B in the solvent tank 80 in order to roughly remove the excess lubricant 50 when the lubricating film 15 is made thin. Then, the magnetic disk substrate 10 pulled up from the solvent tank 80 is carried into the chamber 90.

The inside of the chamber 90 is the magnetic disk substrate 10.
It is filled with the organic solvent vapor 61 at a higher temperature, and is transported in the atmosphere of the organic solvent vapor 61 at a constant speed (while the substrate 10 is kept in the arrangement state with the radial direction being the vertical direction). In addition, the organic solvent vapor 61 is condensed on the surface of the film of the lubricant 50 and is dropped, whereby the lubricant 50 is dissolved from the surface layer and gradually removed.

That is, dew condensation is uniformly generated on the surface of the lubricant 50, and the surface of the lubricant 50 is covered with a thin film of the organic solvent 60. Then, the dissolved lubricant 50 gradually moves downward so as to precipitate in the film of the organic solvent 60,
It drops from the lower end of the magnetic disk substrate 10 together with a drop of the organic solvent 60.

However, the closer to the surface to be coated, the stronger the adhesion of the lubricant 50 to the surface to be coated. Therefore, when the thickness of the lubricant 50 decreases to a value equivalent to a monomolecular film, dew condensation and gentle removal by dripping are carried out. In the process, the removal of the lubricant 50 becomes impossible, and the removal process is substantially finished at that point. That is,
Since the lubricant 50 is not completely removed, the extremely thin and uniform lubricant film 15 can be easily formed without strictly controlling the processing conditions.

When the temperature of the magnetic disk substrate 10 (strictly speaking, the temperature of the lubricant 50) reaches the temperature of the organic solvent vapor 61, the dew condensation stops. Therefore, in order to maintain the dew condensation for a long time, the magnetic disk substrate It is necessary to place 10 inside the chamber 90 in a state of being cooled to room temperature or lower.

In that case, as a cooling method,
Prior to loading into the chamber 90, the magnetic disk substrate 1
It is possible to use a method of providing a cooling chamber for cooling 0 in the route R, a method of incorporating a semiconductor cooling element or the like in the transporting means, and cooling the inside of the chamber 90 as necessary.

Although not shown, in the lubricating film forming apparatus 100, for example, before the application of the lubricant 50, the surface energy of the magnetic disk substrate 10 is increased to improve the adhesion of the lubricant 50. Friction processing means are provided.

The friction processing means is configured to rotate the magnetic disk substrate 10 and press a polishing pad against the magnetic disk substrate 10 to rub the surface to be coated with the lubricant 50.

Although the dipping method is used as the coating method for the lubricant 50 in the above-mentioned embodiments, various methods such as a spray method, a spin coating method, and a vapor deposition method may be appropriately adopted depending on the lubricant used. be able to. Further, the dipping method was also used for the treatment for roughly removing the lubricant 50 in order to shorten the time required for removing the surplus lubricant 50. However, the dipping method combined with ultrasonic cleaning and the dipping method in which the solvent is made to flow are also used. Alternatively, a spray cleaning method may be used.

In the above-described embodiment, the frictional treatment of rubbing the surface to be coated is performed before the lubricant 50 is applied. However, this frictional treatment may be performed before carrying the lubricant 50 into the chamber 90. It may be performed after the application of 50. As the member for rubbing the coated surface, non-woven paper, cloth, felt, or the like can be used in addition to the polishing pad.

In order to check the quality of the lubricating film 15 formed by the above-described forming method, the lubricant 5 is used as Examples 1 to 3 as follows.
0 and the material of the organic solvent 60 are selected to prepare samples, and a test of continuously sliding a slider made of Mn-Zn ferrite is performed on each of these samples to measure the change in friction coefficient and The operating state and changes in the surface of the sample were observed. The magnetic disk substrate 10 of each sample was made of the above-mentioned material.

Here, in the sample of Example 1, a lubricating liquid (trade name: KRYTOX 143AD) manufactured by DuPont and containing perfluoropolyether as a main component was mixed with fluorocarbon (trade name: Freon TF) at a ratio of 1/1000. A lubricant diluted to a concentration was applied by a dipping method, dried at room temperature, rubbed with a cloth buff, and placed in fluorocarbon vapor to form a lubricating film 15.

In the sample of Example 2, a lubricant obtained by diluting a lubricating fluid (trade name: FOMBLINAM 2001) manufactured by Montefluos Co., Ltd. with Fluorinert to a concentration of 1/20000 is applied by a dipping method and dried at room temperature to obtain a fluorocarbon vapor. The lubricating film 15 was formed by disposing it inside.

In the sample of Example 3, behenic acid, which is one of saturated fatty acids, was used as a lubricant, which was applied by the vapor deposition method, and then roughly removed by immersion in acetone, and then at 5 ° C.
The lubricating film 15 was formed by arranging it in the fluorocarbon vapor in a state of being cooled.

As Comparative Examples 1 to 3, Examples 1 to 3 were used.
A material was selected in the same manner as in 1 above, a sample was prepared by a conventional forming method, and the same measurement and observation as in Examples 1 to 3 were performed.
In the sample of Comparative Example 1, the above-mentioned lubricating liquid (trade name is KRYT
OX143AD) was diluted with fluorocarbon to a concentration of 1 / 100,000 to apply a lubricant by spin coating to form a lubricant film. In the sample of Comparative Example 2, the above-mentioned lubricating liquid (trade name is FOMBLIN AM 2001)
A lubricant film was formed by applying a lubricant diluted with Fluorinert to a concentration of 1 / 50,000 by a spin coating method. In the sample of Comparative Example 3, behenic acid was applied by the vapor deposition method, and the excess lubricant was removed by wiping with a non-woven paper to form a lubricating film.

As shown in Table 1, the results of measurement and observation show that, in comparison between Example 1 and Comparative Example 1, at the start of sliding and the number of times of sliding (the number of rotations of the sample) was 4,000. There was no significant difference in the coefficient of friction, and both had good lubricating action. However, in Example 1, the number of slides was 1000
Even if the value exceeds 0, the lubricant that causes the head crash does not accumulate on the slider and drop off on the disk side (hereinafter, referred to as "deposit / drop off"), whereas in Comparative Example 1, sliding occurs. Accumulation and dropping occurred when the number of times reached 4,500.

In comparison between Example 2 and Comparative Example 2,
In Example 2, the head adsorption and the deposition / shedding did not occur even when the number of sliding times exceeded 10,000, but in Comparative Example 2, the friction coefficient was 0.7 or more at the start of sliding (when head adsorption occurred. The slider did not slide smoothly.

In comparison between Example 3 and Comparative Example 3,
In Example 3, the head adsorption and deposition / shedding did not occur even when the sliding number exceeded 10,000, but in Comparative Example 3, the deposition / shedding occurred when the sliding number reached 6000.

That is, the lubricating film 1 formed by the forming method of the present invention
No. 5 is a stable film that is not subjected to surface roughening treatment but has no head adsorption, and is a stable film that does not deposit or drop, and is used for ensuring the reliability of the magnetic disk device. It was confirmed that it was an excellent lubricating film.

[0039]

[Table 1]

[0040]

According to the present invention, it is possible to form a lubrication film having a stable film state and good lubricity, and prevent the occurrence of head adsorption or head crush to improve the reliability of magnetic storage. it can.

According to the second aspect of the present invention, the adhesion of the lubricating film to the magnetic disk substrate can be increased, and the lubricating property can be improved. According to the invention of claim 3,
It is possible to improve the efficiency of forming the lubricating film.

According to the fourth aspect of the present invention, when automating the formation of the lubricating film, it is possible to stabilize the conditions for forming the lubricating film and prevent contamination of the surroundings of the forming apparatus.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a configuration of a main part of a lubricating film forming apparatus according to the present invention.

FIG. 2 is a diagram showing a configuration of a magnetic disk according to the present invention.

[Explanation of symbols]

 1 Magnetic Disk 10 Magnetic Disk Substrate 50 Lubricant 61 Organic Solvent Vapor 100 Lubricating Film Forming Device 90 Chamber 90A Inlet 93 Cooling Means

Claims (4)

[Claims] 1. A magnetic disk substrate (10) coated with a lubricant (50) is placed in an atmosphere of an organic solvent vapor (61), and an excessive lubricant ( 50) A method for forming a lubricating film for a magnetic disk, which comprises dissolving and removing 50). 2. A friction treatment for surface activation of the surface to be coated with the lubricant (50) before the magnetic disk substrate (10) is placed in the atmosphere of the organic solvent vapor (61). The method for forming a lubricating film of a magnetic disk according to claim 1, further comprising: 3. The formation of a lubricating film for a magnetic disk according to claim 1, wherein the magnetic disk substrate (10) is arranged in a cooled state in the atmosphere of the organic solvent vapor (61). Method. 4. A lubricant inlet (90A) for a magnetic disk substrate (10) coated with a lubricant (50), the lubricant (5) being provided.
Organic solvent vapor (6) for partially dissolving and removing (0)
Lubrication, characterized in that it comprises a chamber (90) for containing 1) and a cooling means (93) for condensing the organic solvent vapor (61) in order to suppress outflow from the carry-in port (90A). Film forming equipment.