JPH0770053B2 - Surface lubrication method for magnetic disk media - Google Patents

Description

The present invention relates to a surface lubrication method for uniformly forming a thin layer of a lubricant on the surface of a magnetic disk medium.

[Prior art]

Like a magnetic tape or floppy disk drive,
In a magnetic recording device in which a magnetic film is formed on a substrate of a flexible body such as so-called PET, the magnetic head and the magnetic recording medium are traveling in contact with each other when recording / reproducing a signal.

On the other hand, in a magnetic disk device using a magnetic disk medium having a magnetic film formed on a rigid substrate such as aluminum, a floating head slider, which is a dynamic pressure gas axis, is used to move the magnetic head to a minute gap on a disk medium rotating at high speed. Recording and playback are being performed by surfacing.

Here, when the floating clearance of the magnetic head is reduced due to disturbance such as mixing of dust, vibration of the mechanical components such as a positioner, and the magnetic disk medium, the magnetic head and the magnetic disk medium are intermittently contacted at high speed.

In recent years, contact start stop (CSS) that rotates and stops the drive motor that rotates the disk medium with the magnetic head in contact with the magnetic disk medium.
A magnetic disk drive of the type is becoming mainstream, and when the rotation of the disk medium is below a certain level, the magnetic head does not reach the desired value of the clearance, so that contact traveling between the head and the medium occurs.

In this case, the magnetic film itself of the magnetic disk medium does not have lubricity, or even if it does have extremely low lubricity, the magnetic head or the magnetic film of the magnetic disk medium wears out when contact travel occurs for a long time, So-called head crash occurs.

Therefore, in general, the surface of the magnetic disk medium is overcoated with a lubricant to improve its lubricity.

However, if a large amount of the lubricant is used on the entire surface or a part of the disk medium, the lubricating film becomes thick and the coefficient of friction between the head and the disk medium becomes large, and when the rotation of the drive motor is started, adsorption occurs and both are damaged.

Therefore, it is necessary to use an appropriate amount of the lubricant that overcoats the surface of the disk medium and to make it uniform in the range that does not increase the friction coefficient.

In particular, a continuous thin film medium with a magnetic film formed by sputtering or plating has a smoother surface than the coating medium coated with conventional iron oxide fine particles, so an extremely thin lubricating film thickness of 10 to 100Å can be formed. This is important in preventing the magnetic head and the magnetic disk medium from being attracted to each other.

Spin coating, spraying, dipping, and the like are available as methods for applying a lubricant to a continuous thin film medium on which a magnetic film has been formed by sputtering or plating. Among them, the spin coating method has advantages such as being simple and suitable for mass production.

In the conventional spin coating method, the lubricant solution is continuously dropped onto the magnetic disk medium rotating at a low speed, and the entire surface of the medium is covered with the lubricant solution. After ˜3 seconds has elapsed, the disk medium was rotated at a high speed with a rise time of 5 to 10 seconds to wipe out excess lubricant solution to form a lubricating film on the surface of the magnetic disk medium.

However, it is difficult to form a uniform and thin film of the lubricant solution by this method.

[Object of the Invention]

An object of the present invention is to provide a surface lubrication method for a magnetic disk medium, which allows a lubricating film having a thickness of 10 to 100Å to be uniformly formed on the magnetic disk medium and a low coefficient of friction to be stably obtained.

[Structure of Invention]

For this reason, the surface lubrication method of the magnetic disk medium of the present invention is a method in which a lubricant solution having a kinematic viscosity of 2 cst or less in which the lubricant is diluted with an organic solvent is dropped on the surface of the magnetic disk medium rotating at a low speed. A surface lubrication method in which after covering the entire surface with a lubricant solution, the above-mentioned magnetic disk medium is rotated at a high speed to wipe off excess lubricant solution to form a lubricating film on the surface of the magnetic disk medium. While the magnetic disk medium was rotated at a constant low speed of 30 to 300 rpm, the dropping of the lubricant solution was continued, and at the same time as the dropping was completed, the high speed rotation of 1000 to 4000 rpm was switched with a rising time within 3 seconds.

〔Example〕

Examples of the surface lubrication method for the magnetic disk medium of the present invention will be described below. First, an outline of an example of a spin coater used to carry out the present invention will be described with reference to FIG.

In the figure, reference numeral 1 is a spindle, to which a magnetic disk medium 2 is attached and which is rotated by a motor 3.

Reference numeral 4 denotes a discharge nozzle mounted near the surface of the magnetic disk medium 2, and the discharge nozzle 4 is mounted on a pump 5.

The pump 5 sucks the lubricant solution 7 stored in the airtight lubricant solution storage container 6 having fine holes for intake, and discharges it from the nozzle 4.

Reference numeral 8 is a sequencer for automatically controlling the rotation speed of the motor 3 and the start / stop of the pump 5.

The above is the outline of the spin coater.

In the surface lubricant of this embodiment, first, a lubricant solution 7 diluted with an organic solvent to have a kinematic viscosity of 2 cst or less is stored in a lubricant solution storage container 6, and the magnetic disk medium 2 is attached to the spindle 1.
, And the motor 3 is started to rotate the spindle 1 to rotate the magnetic disk medium 2 at a low speed of 30 to 300 rpm.

When the number of rotations is stable, the pump 5 is activated to continuously drop the lubricant solution 7 on the surface of the magnetic disk medium 2 from the nozzle 4, and the entire surface of the magnetic disk medium 2 is covered with the lubricant solution 7.

At this time, the operation of the pump 5 is stopped to stop the dripping of the lubricant solution 7, and at the same time, the rotation speed of the magnetic disk medium 2 is switched to a high rotation speed of 1000 to 4000 rpm with a rising time of 3 seconds or less. The lubricant solution 7 is wiped off to form a thin film of the lubricant solution 7 on the surface of the magnetic disk medium 2.

The above sequence and the rotation mode of the magnetic disk medium 2 are shown in FIGS. 2 (a) and 2 (b).

The magnetic disk medium 2 may have a protective film (eg, SiO ₂ ) formed on its surface.

〔Example〕

 The experimental conditions are as follows.

Magnetic disk: Ni-Co-P plating medium coated with SiO ₂ protective film Lubricant solution: 0.07% fluorinated carbon solution of perfluoropolyether with polar groups at the molecular ends (2 cst or less) Slow rotation ... … 150 rpm for 10 seconds Rise time …… 2 seconds High speed rotation… 3000 rpm for 5 minutes The state of the lubricating film obtained by this experiment is shown by the solid line in FIG.

The dotted line in FIG. 3 is based on the conventional method and is shown in FIG. 3 for comparison. The conditions are as follows.

Low-speed rotation: 150 rpm 10 seconds 2-3 seconds after dripping stop Rise time: 8 seconds High-speed rotation: 3000 rpm 5 minutes As is apparent from FIG. 3, the experimental example according to the present invention is compared with the conventional method. It is found that the lubricating film thickness in each direction of the circumference of the magnetic disk is extremely uniform in the Angstrom order.

FIG. 4 shows the relationship between the lubricating film thickness and the friction coefficient. In the figure, it can be seen that the friction coefficient gradually increases as the lubricating film thickness increases, and increases rapidly when the lubricating film thickness exceeds 20Å. Here, in the conventional method shown in FIG.
Since there are disk rotation positions that exceed Å, it can be seen that the friction coefficient sharply increases in this area, the stability during head / medium contact travel is reduced, and the risk of head crash is high.

In the above experimental example, perfluoropolyether having a polar group at the molecular end was used as the solute of the lubricant solution,
However, the present invention is not limited thereto. Liquid carbon fluoride, solid carbon fluoride, a mixture of liquid carbon fluoride and solid carbon fluoride, a higher fatty acid, a higher fatty acid metal salt, and a mixture of a higher fatty acid and a higher fatty acid metal salt. Various kinds of lubricants such as can be applied.

〔The invention's effect〕

As described above, according to the lubrication method of the present invention, the lubricating film on the surface of the magnetic disk medium is formed to have a uniform film thickness of 10 to 100Å and with good reproducibility, and good lubricating characteristics can be obtained. Therefore, it has a remarkable effect on the improvement of the reliability against the thinning of the lubricating film, the increase of the recording density and the operation stability of the head, and the low flying of the magnetic head, and the application to the magnetic disk device adopting the CSS type etc. And is extremely effective.

[Brief description of drawings]

FIG. 1 is a perspective view of a spin coater for implementing the present invention, FIG. 2 (a) is a characteristic diagram of a control sequence of the spin coater for realizing the lubrication method of the present invention, and (b) is a rotation of the magnetic disk. FIG. 3 is a characteristic diagram of the mode, FIG. 3 is a characteristic diagram of the film thickness distribution of the lubricating film formed by the present invention and the conventional lubrication method, and FIG. 4 is a characteristic diagram showing the relationship between the lubricating film thickness and the friction coefficient. 1 ... Spindle, 2 ... Magnetic disk, 3 ... Motor, 4 ... Discharge nozzle, 5 ... Pump, 6 ... Airtight lubricant solution storage container, 7 ... Lubricant solution, 8 ... Sequencer .

Claims (1)

[Claims] 1. A lubricant solution having a kinematic viscosity of 2 cst or less in which a lubricant is diluted with an organic solvent is dropped on the surface of a magnetic disk medium rotating at a low speed, and the whole surface is coated with the lubricant solution. A surface lubrication method in which the medium is rotated at a high speed to wipe off an excessive lubricant solution to form a lubricating film on the surface thereof, wherein the magnetic disk medium is rotated at a constant low speed of 30 to 300 rpm. The surface lubrication method is characterized in that the lubricant solution is continuously added while being dropped, and at the same time as the end of the drop, the rotation is switched to a high speed rotation of 1000 to 4000 rpm within a rise time of 3 seconds.