JPH0453027A - Magnetic disk excellent in durability - Google Patents

Abstract

PURPOSE:To improve sliding durability and adsorption resistance by making the lubricant film of a CSS zone thicker than the lubricant film of a data area in a magnetic disk having surface coarseness higher than the surface coarseness of the data area. CONSTITUTION:The surface coarseness of the CSS zone is higher than that of the data area, and the ratio of average lubricant film thickness between the CSS zone and the data area is set within a range from 1:0.1 to 0.8. On the other hand, in the CSS zone enlarging the surface coarseness, the quantity of lubricant is made much and in the data area reducing the surface coarseness, the quantity of lubricant is made a little. As a manufacture, a spin coat method using two nozzles is applied, and solvent and lubricant is dropped down from the first nozzle at the central side of the disk. Only the solvent or the lubricant including much solvent is dropped down from the second nozzle at a boundary between the CSS zone and the data area, and the lubricant from the second nozzle onto the data area at an outer peripheral part is diluted. Then, after vaporizing the solvent, the lubricant is diluted, and the disk can be obtained with the difference of the lubricant film between the CSS zone and the data area.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk with improved durability, and in particular to an improvement in the durability of a magnetic disk having a CSS zone, that is, in sliding friction and frictional characteristics, and in a magnetic head. The present invention relates to a magnetic disk that can obtain a low flying height.

The object of the present invention is a magnetic disk having such a CSS zone, and relates to the structure of a lubricating film on a magnetic disk medium in which the surface roughness of the CSS zone is increased.

[Prior Art] Some magnetic disks have CSS zones defined due to the structure of the disk drive, as shown in FIG. The medium structure of a magnetic disk consists of Ni plating on an aluminum substrate, an intermediate layer, a metal magnetic layer, a protective film of carbon or silica, and a lubricating film.The magnetic layer can be formed by either plating or sputtering. It is also done. The specific applicable media are mainly the two types of thin film media shown below.

・Metsuki type media lubricating film (perfluoroalkyl polyether) Sputter car or Sio2 protective film (300-500 people) Magnetic layer (CoNiP, CC-P% Co-X-P etc. (300
~500 people)) Ni-P intermediate layer (10~20 μm) A1 substrate sputtered media lubricating film (perfluoroalkyl polyether) Sputtered carbon protective film (300~500 people) Magnetic layer (CoCrX
, CoNi, etc. (300 to SoO people)) Ni-P intermediate layer (10 to 20 μm) A1 substrate Disk drives of magnetic recording devices are becoming smaller and lighter, and the magnetic disks are also becoming more dense. Along with this, there is an increasing demand for smoothing of the medium surface roughness in order to lower the flying height of the magnetic head. When the flying height of the magnetic head is lowered, there are many opportunities for the magnetic head to come into contact with minute protrusions such as texturing attached to the magnetic disk, resulting in increased wear on both parts and a decrease in durability.

Additionally, when the surface roughness of the medium is smoothed (surface roughness is reduced), the contact area between the magnetic head and the medium surface increases, increasing the sliding frictional resistance, and also causing the magnetic l\\rad adsorption phenomenon ( When the magnetic head is placed in contact with the disk surface for a long time, the meniscus phenomenon of the lubricant (perchloroalkyl polyether) and the condensation of moisture in the atmosphere occur.
(a phenomenon in which the magnetic head and the medium penetrate between the magnetic head and the medium and are attracted to each other by their surface tension) occurs.

Conventionally, a textured substrate in which regular concentric grooves are formed in the circumferential direction of the magnetic disk has been employed in order to improve the magnetic recording density and the flying ability of the magnetic head. Furthermore, a magnetic disk has been proposed in which the surface roughness of the CSS zone and the data area are changed, that is, the surface of the CSS zone is roughened.

[Problems to be Solved by the Invention] As mentioned above, magnetic disk drives are increasingly required to be smaller and have lower torque. It has become impossible to improve the durability of magnetic heads and increase the recording density.

In addition, for a magnetic disk with a roughened CSS zone, if a lubricant film is formed using the spin code method, for example, if the thickness of the lubricant film is set based on the CSS zone, the data area with small roughness will be as shown in Figure 2. As a result, the film thickness AB from the surface of the lubricating film to the tips of the ridges of the protective film increases. Therefore, in the data area, head adsorption occurs the moment the disk and head are assembled into the magnetic disk drive, and excess lubricant is collected by the head during head seek, generating debris and deteriorating the head flying characteristics. .

Conversely, if the lubricant film thickness is set based on the data area, the lubricant film thickness will be insufficient in the CSS zone where the roughness is large, resulting in a disadvantage that sliding durability will be reduced.

It is known that the amount of lubricant applied must be adjusted depending on the surface roughness of the disk (for example, Tricebbs WS 5 p149), but when the surface roughness of a single disk is changed in this way, , as mentioned above, either surface roughness had to be used as the standard.

That is, in the conventional lubricant film forming technology, the film thicknesses of the CSS zone and the data zone are approximately constant. For this reason,
If the lubricant film thickness is set in the CSS zone (rough surface area), the film thickness in the data area will be thicker than the roughness, and ■ When the disk and head are installed in the drive, head adsorption will occur instantaneously.

■ Excess lubricant is collected by the head during head seek, generating debris and deteriorating head flying characteristics. Therefore, it adversely affects electromagnetic conversion characteristics.

On the other hand, if the lubricant film thickness is set in the data area (smooth area), there will be a shortage of lubricant in the CSS zone, and no improvement in durability can be expected.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a magnetic disk that can provide sliding durability, that is, a low flying height of the magnetic head, in each data area of the CSS zone, and has excellent adhesion resistance.

[Means for Solving the Problem] In order to solve the above object, the present inventors investigated the relationship between the durability of the magnetic disk and the low flying height of the magnetic head, the surface roughness of the magnetic disk, and the thickness of the lubricant film. As a result of various studies, it was discovered that by using a two-nozzle spin code method, different film thicknesses could be obtained even on the surface of a single disk, and the present invention was completed.

That is, the present invention provides C
The gist of this is a magnetic disk in which the lubricant film in the SS zone is thicker than the lubricant film in the data area.

L action] The present invention will be described in detail.

(a) Roughening the surface roughness of the CSS zone Making the combination of surface roughness of the media rougher than that of the data area is
This has the effect of improving head attraction in the S zone and lowering the flying height of the magnetic head in the data area.

The combination of surface roughness of the medium varies depending on the type of magnetic disk, and typical examples are shown in Table 1.

In the case of type A, the ratio of the lubricant film thickness between the CSS zone and the data area is 1:0.2 to 0.8.

In the case of type B, the ratio of the average lubricant film thickness between the CSS zone and the data area is 0.1 to 0.4.

In the case of type C, the ratio of the average lubricant film thickness between the CSS zone and the data area is 1:0.2 to 0.8.

Therefore, the ratio of the average film thickness of the CSS zone to the data area of the disc of the present invention is 1. : In the range of 0.1 to 0.8.

In addition, the CSS zone has a radius of 12 in the case of a 3.5φ disk.
．． 5 to 23.0±2.0 m, and in the case of a 5,25φ disk, the radius is 20.0 to 34.0±2.0 mm (this may vary depending on the magnetic disk drive).

(b) Thickness of the lubricant film The lubricant is necessary to reduce friction and wear between the head and the medium. In other words, if the amount of lubricant applied is small, the wear on both will increase, and if it is large, the friction coefficient will increase significantly, and if the head and the medium are left in contact for a long time, a severe adsorption phenomenon will occur. .

Therefore, in the magnetic disk of the present invention, as shown in Fig. 1, the amount of lubricant is increased in the CSS zone where the surface roughness is large, and the amount of lubricant is decreased in the data area where the surface roughness is small, thereby compensating for the above drawbacks. It is something that

In addition, Table 1 shows suitable lubricant film thicknesses in combination with surface roughness.

Part 1 table Media surface roughness (Rtm) (person) Lubricant film thickness (person) 300~50[') 200 or less 15-30 6-12 500 or more 500 or more 200 or less 200-500 30-60 30-60 6～ko2 12-24 (C) Next, the manufacturing method will be described.

As shown in Figure 2, using the spin code method with two nozzles, solvent + lubricant is applied from the first nozzle located at the center of the disk to the second nozzle located at the boundary between the CSS zone and the data area. By dropping a lubricant containing only a solvent or a large amount of solvent from the second nozzle, the lubricant on the data area on the outer periphery from the second nozzle is diluted, and the lubricant film after the solvent has evaporated becomes thinner. This results in a disk with a different lubricant film between the CSS zone and the data area.

[Example: Using a 5.25φ magnetic disk, from 20mm in diameter to 34mm
rnm as the CSS zone, and the area from the diameter of 34 mm to the outer periphery as the data area, create the surface roughness of the medium as shown in Table 2, and use the spin code method using the two-point nozzle method.
The thickness of the lubricating film was varied as shown in Table 2.

1 cavity! 1,) Electron = 1 E ;" 3 7 6 3 8 Effect 2 3:!To 蝮i ,) Old 1 The surface thickness of the medium was measured using a Talystep (stylus diameter: 2.5 μm square) manufactured by Rank Taylor Hobson. ).

The thickness of the lubricant film was measured using a surface analyzer ESCA manufactured by PerkinElmer Co., Ltd., and calculated from the ratio of CtS photoelectron intensities of CF bonds (carbon-fluorine bonds) in the lubricant. Therefore, the range from the center line of the unevenness shown in FIG. 2 to the surface was measured.

The coefficient of friction between the medium and the head was measured using an abrasion tester manufactured by Kubota Combs Co., Ltd. - Disc rotation speed: 1 rpm, load: 7.
The test was carried out under the conditions of 2 g and a flying height of 0.15 μm. The adsorption coefficient of the head was measured using a magnetic disk drive torque meter method.

Next, Table 3 shows an example in which the CSS zone Rtm has 700 people and the data area Rtrn has 500 people.

Lubricant film thickness ^ Friction coefficient μf Head adsorption coefficient SS Sub-C3S zone 0, ]5~0,2 0.3~0135 20,000 times or more 3rd surface data area 0.8 or more 1.0 or more Starting CSS zone 0. 15~0.2 0.3~0.35 20,000 times or more Bright data area 0.2~0.25 0.35~0.45 l) The relationship between surface roughness, lubricant film thickness, and durability is Shown in the figure. From this figure, the optimum lubricant film thickness for each roughness was selected. Note that the basic goal for CSS characteristics is to aim for a thicker layer within each margin.

In this way, Rtm 700 people have 32 people, Rtm 5 people
For 00 people, the film thickness of 27 people was selected.

2) With a uniform lubricant film thickness in the conventional method, the data area friction coefficient and head adsorption coefficient are 4 to 5 times higher, making the medium impossible to incorporate into a drive.

3) However, in the medium of the present invention, the data area friction coefficient and head adsorption coefficient are relatively low, and the medium can be easily incorporated into a drive.

4) All lubricant film formation was performed using the spin code method.

The effect is produced, It is extremely effective industrially.

[Brief explanation of drawings]

Figure 3 shows the lubricant film thickness and friction coefficient, It is a relationship diagram. Head adsorption coefficient

Claims (1)

[Claims] It has an area (contact start/stop zone, hereinafter abbreviated as CSS zone) in which the magnetic head is always placed when the magnetic disk moves or stops, and the lubricating film of the CSS zone covers the data area. A highly durable magnetic disk characterized by having a film thickness greater than that of a lubricating film.