JPH10177715A - Magnetic disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a head floating characteristic and a slide resistant characteristic by forming a large number of uniform fine grooves and fine projection parts on a substrate of aluminum alloy, anode oxide aluminum, aluminum alloy coated with Ni-P plating, etc., or glass or plastics, etc. SOLUTION: The large number of uniform fine projected parts several nm to several tens nm in height and several thousand pieces/mm<2> to several hundred thousand pieces/mm<2> in density of existence formed on the magnetic disk substrate are brought into contact with a slider of a magnetic head at the CSS time of the head, receiving a load of the head. Then, these fine projection parts act to keep a lubrucative film applied on the magnetic disk surface and also to prevent sticking of themselves to the magnetic head. Moreover, since the large number of fine projection parts come in contact with the head slider surface, surface pressure of each individual fine projected part is diminished, so that a change, i.e., deformation and wear of the fine projected parts due to repetition of CSS is reduced, and hence the surface status is maintained under the initial state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the surface properties of a thin-film magnetic disk, and more particularly to a magnetic disk having a surface property suitable for the head floating characteristics, CCS characteristics, and head-adhesive sliding resistance characteristics of the thin-film magnetic disk. About.

[0002]

2. Description of the Related Art Conventionally, an underbody in which fine grooves are formed on a substrate for a thin film magnetic disk (hereinafter, the surface processing for forming the fine grooves is called texture processing) is disclosed in
As described in Japanese Patent Application Laid-Open No. 219227/1992, the surface irregularities of the base body have a maximum surface roughness of 0.02 to 0.1 μm, and the nonmagnetic metal layer 31 is formed on the base body 1 as shown in FIG. ,
As a result of forming the magnetic thin film medium 32, the holding power of the magnetic thin film was 500 Oe or more within the above range of the maximum surface roughness, and the nonmagnetic metal film (chromium film) could be thinned, so that the productivity was improved. In addition, as a result of the contact start / stop test, no scratch was found on the disk surface after 20,000 times, but when the maximum surface roughness was 0.1 μm or more, a head crash was likely to occur, and when the texture was not applied. It is stated that scratches occurred after 5000 contact start / stops, causing a head crash.

Here, the conventional texture processing includes, for example, a method shown in FIG. 12 and a disk processing apparatus as described in Japanese Patent Application Laid-Open No. 54-23294. In the figure, reference numeral 2 denotes a base substrate relating to a disk, and a center axis of a pair of contact rollers 8 (both elastic bodies made of rubber or the like) is arranged in the radial direction of the disk so as to sandwich the disk. The polishing tape 4 running in the vertical direction is interposed between the contact roller 8 and the disk 2. And
This is a method of simultaneously processing both surfaces of the disk by pressing the contact roller and rotating the disk, and simultaneously sliding the contact roller 8 back and forth in the radial direction of the disk 2. According to this texture processing, a fine groove without polishing unevenness can be formed by a polishing tape, but with this shape, an unstable bulge occurs at the shoulder of the groove, and this bulge is caused by the fine protrusion. There was a problem that remained on the surface.

[0004]

In the prior art, a non-magnetic metal layer (chromium film) is formed by forming irregularities (texture processing) having a maximum surface roughness of 0.02 μm to 0.1 μm on the surface of a base body. Even if the thickness is reduced, the magnetic thin film medium (C
o-Ni) is 500 Oe or more, and 2
Satisfies 10,000 times of contact start / stop characteristics,
It is stated that no head crash will occur. However, in the prior art, when only the maximum surface roughness is specified, the base substrate surface coated with aluminum alloy, anodized aluminum, or Ni-P plating or the like is subjected to texturing to form fine grooves. A fine projection is generated on the shoulder of the head, and due to the fine projection, when the head is subjected to a floating test with a narrow floating gap, for example, a head floating gap of 0.2 μm, the head and the fine projection intermittently contact each other, The point at which head crash occurs which impairs the head flying stability, and the outermost surface of the disk in the CSS test changes due to the sliding of the head.
It is important to define the fine protrusions by texture processing because the horizontal resistance exerted on the head increases and a head crash occurs.
SS and head crash cannot be explained, and there is no arrangement for the fact that the shape and frequency of the protrusion from the average surface is more important than the maximum surface roughness, which improves head crash and CSS characteristics. There is a problem that there is no most important presentation about the surface irregularities of the underlying substrate to be formed.

[0005] Here, as shown in FIG. 29, the fine projection is measured in the approximate circumferential direction of the disk, or in the radial direction of the disk with respect to the textured surface formed in a spiral shape. Regarding the surface roughness curve, individual peaks having a convex direction from the center line of the roughness curve, that is, fine heights are shown. In addition, the height of the fine protrusion indicates the distance between each top and the center line.

An object of the present invention is to provide a head crash factor,
Provides a magnetic disk with excellent head flying characteristics and high reliability using a textured base substrate such as Ni-P plating that forms the optimum surface properties in consideration of the sliding characteristics such as CSS characteristics and head adhesion. Is to do.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a magnetic disk substrate such as an aluminum alloy, anodized aluminum, an aluminum alloy coated with Ni-P plating or the like, or a substrate made of glass or plastic. It is characterized by forming uniform fine grooves and fine protrusions.

These fine grooves and fine projections are formed on the shoulder of the groove by forming a fine groove on the substrate surface with a cutting tool such as a diamond tool or a fine abrasive, as shown in FIG.
The raised portion 36 is formed as shown in FIG. The swelling height of these fine protrusions is set by the depth and size of the groove 37, and the frequency of the fine groove is set by processing conditions such as the density of fine abrasive grains and tool feed.

Here, the essential point of the surface properties of the magnetic disk is to satisfy various characteristics of the magnetic disk such as electric characteristics, CSS characteristics, head adhesion and the like without causing head crash. Since a magnetic disk has a narrow head floating gap in order to achieve a high density, a super smooth surface is required on the disk surface to avoid collision between the head and the disk. On the other hand, due to the need to shorten the process time,
It comes into contact with the head and disk when stopped, and floats with the rotation of the disk. A so-called contact start / stop (hereinafter abbreviated as CSS) is performed. For this reason, when the disk surface is a smooth surface, that is, when the surface roughness is very small, the head and the disk will stick to each other due to the lubricant on the disk surface or the moisture in the atmosphere when the disk stops, and the head support during the rotation of the disk. There has been a problem that the gimbal and the arm are damaged, and the rotation cannot be performed. 13 and 14 show the results of experiments performed by the inventors. The relationship between the height, existence density, head floating characteristics, and head adhesive force of a fine protrusion by texture processing (details will be described later) formed on a base substrate using a polishing tape is shown. From this result, it is understood that there is an optimum range of the surface texture satisfying the two characteristics of the head flying characteristics and the head adhesive force.

Further, the relationship between the above-mentioned surface properties and CSS characteristics will be described with reference to the drawings.

FIG. 27 shows a cross-sectional shape of a surface obtained by texturing a base substrate using fine abrasive grains, and fine projections are present with variation.

Here, a method for measuring the cross-sectional shape of the textured surface will be described. The cross-sectional shape is a curve measured in the radial direction of the base substrate using a stylus having a stylus shape of 0.1 μm × 2.5 μm using a surface roughness meter Talistep (manufactured by Rank Taylor Hobson). is there. The Abbott bearing curve and peak count distribution curve of this cross-sectional shape were obtained by A / D-converting the output signal from the tally step and setting the sampling interval to 40 nm by computer processing.

As shown in FIG. 28, the load curve of the Abbott having this cross-sectional shape has a large gradient in the range where the cutting length ratio is small, that is, in the range of the portion A in FIG. When the magnetic head repeats CSS on the surface as shown in FIG. 27, the fine protrusion has less contact with the head slider surface,
As a result, the surface pressure W / S (W: head load, S: real contact area between the head slider and the disk surface) becomes large, so that abrasion or deformation occurs sharply, and a film is formed on the underlying substrate on which the fine protrusions are formed. The magnetic medium and the protective film having a thickness of several tens nm are greatly damaged. On the other hand, when the yield strength of the fine protrusion is σ, the wear or deformation of the fine protrusion occurs sharply when σ <W / S, and decreases when σ ≧ W / S. Therefore, the true contact area is increased by the wear and deformation of the fine protrusion due to CSS, and the true contact area S satisfies the above-mentioned σ ≧ W / S. Is formed without damage, the wear and deformation of the fine projections are almost eliminated, and a stable surface is obtained. Therefore, the undersubstrate having the cross-sectional shape shown in FIG. 27 was further subjected to surface processing to smooth fine projections as shown in FIG.
Formed as a trapezoidal model, increasing the true contact area between the head slider and the disk surface,
If the surface shape has a true contact area satisfying ≧ W / S, the surface pressure of the fine protrusions is reduced. Therefore, wear and deformation of the fine protrusions are almost eliminated by CSS, and a stable and highly reliable surface for a magnetic disk is obtained. You will get The load curve of the Abbott having the cross-sectional shape shown in FIG. 28 is as shown in FIG. 28, and it can be seen that the slope of the load curve on the pole surface is very small as shown in A of FIG.

In an experiment conducted by the present inventors, for a conventional textured surface having a cross-sectional surface as shown in FIG. 27, as an example, the load curve of the Abbott is 5 nm to 10 nm from the top of the cross-sectional curve, that is, the cutting height. 5nm-10
The cutting length ratio in nm is 0.1% or less, and in a magnetic disk using such an undersubstrate, the CSS frequency is 200 times.
A head crash occurred at 0 or less times. Further, the texture processing of the present invention was processed in two stages. The surface as shown in FIG. 28, that is, a cutting height of 5 nm to 10 nm
In the case of a magnetic disk using an undersubstrate having a surface with an Abbott load curve having a cutting length ratio of 0.1 to 10% in the above-described method, the number of CSS times is 20,000 or more, and the magnetic medium and the protective film maintain their respective functions. And maintained a stable surface state.

Further, detailed deformation of the surface of the magnetic disk by CSS was examined. In the experiment by the inventors, on the surface of the substrate subjected to the contact start / stop CSS test on the textured substrate, the surface shape measured from the SEM observation of the disk surface subjected to the CSS test shown in FIG. From the Abbott load curve (discussed in detail later) on the disk surface shown in FIG. 1, the top of the fine projection in the initial state is smoothed by repeated sliding of the magnetic head, and the fine contact between the head and the disk at this time is also smoothed. It was found that the number of protrusions increased. For example, as shown in part A of FIG. 15B, a change in the surface when the CSS frequency is 20,000 times is caused by a fine protrusion having a height of 5 to 10 nm from the top in the initial state due to contact with the slider surface of the magnetic head. And the fine projections are 5-10n from the top in the initial state from the peak count distribution curve of the disk surface at this time shown in FIG.
When the distance was changed by m, the number of fine projections in contact with the magnetic head was several thousand / mm 2 to several hundred thousand / mm 2. That is, when the height of the number of fine protrusions is several tens nm or more, the flying characteristics of the magnetic head are degraded, which may cause a head crash. When the number of small protrusions is small, the surface of the substrate that supports the head load when the head slides in the CSS test, that is, the number of fine protrusions is small and the surface is immediately smoothed with the number of CSSs, and the head tangential force increases, causing a head crash. It will be easier.

On the other hand, if the number of the fine protrusions is small, the surface pressure of the fine protrusions receiving the head load increases, so that the fine protrusions are liable to be reduced or worn away.
When the lubricant layer and the protective film layer are more susceptible to damage, etc., and when the fine density is several hundred thousand / mm2 or more and the existing density is high, the change of the fine protrusion on the substrate by the magnetic head is small, Since the contact area is large, head adhesion is likely to occur due to the effect of lubricant and atmospheric moisture, and the sliding resistance of the magnetic head during CSS increases, causing damage to the gimbal and arm of the magnetic head and difficulty in rotating the disk. I had a problem.

Here, the load curve of the Abbott will be described in detail. The load curve for this Abbott is ABBOT
T-FIRSTONE (OR BEARING RA
This is called TIO) CURVE and is generally used to evaluate the sliding characteristics of a bearing or the like. As shown in FIG. 30, the load curve of this Abbott is obtained by cutting the cross-sectional curve at regular intervals from the top of the cross-sectional curve with respect to the reference length E of the cross-sectional curve (or surface roughness curve) of the surface. 3 shows a curve in which a value obtained by dividing the total of the cut lengths of the respective cross-sectional curves by the reference length E is expressed in percentage for each cut line. At the top of the cross-sectional curve, the cutting length by the cutting line is small, and the cutting length ratio is small. That is, if there is a sliding body on this surface, the sliding body is supported only at the top of the cutting curve at the beginning of sliding, so the pressure receiving area is small, and the surface pressure is large.
The top part is slid frictionally due to the sliding body, and is liable to be worn or deformed. Therefore, in the surface where the cutting length ratio at the top of the sliding curve is large, that is, in the Abbott load curve, the pressure receiving area is in the initial state on the surface where the cutting curve has a small gradient in the range where the cutting length ratio is small. And the surface pressure of each microprojection supporting the sliding body decreases,
The sliding resistance is improved. As described above, the Abbott load curve is one of the evaluation methods for expressing the load capability of the cross-sectional curve of the surface to be slid on the sliding body.

Therefore, the surface properties of the textured substrate are considered in consideration of the flying characteristics of the head, the head load, and the surface change due to friction and abrasion caused by the head sliding. It is desirable to have a surface on which uniform fine protrusions are formed with a thickness of several tens nm and a frequency of the fine protrusions of several thousand / mm <2> to several hundred thousand / mm <2>. From this point of view, the optimal surface for the magnetic disk substrate is a pseudo-circumferential fine groove formed on the substrate surface as shown in FIG. The height of the fine projection is several nm to several tens nm and uniform, and the existence density on the substrate surface is several thousand / mm2 to several hundred thousand / mm2.

There are various methods for obtaining such a surface textured substrate. One method is, for example,
As shown in FIG. 1, using a fixed abrasive such as a polishing tape described in JP-A-54-23294, a processing head is reciprocally slid in a radial direction of a substrate with respect to a mirror-finished substrate. Then, a processing method of forming a pseudo-circular fine groove is applied, and a fine bulge generated at a groove shoulder is reduced by several nm.
To several tens nm. Further, by using a polishing tape having finer abrasive grains than the above-mentioned polishing tape and rotating the substrate at a light load and at a high speed, a process for making the height of the fine projections uniform is performed. The frequency of the fine protrusions can be arbitrarily changed by changing the grain size of the polishing tape and controlling the number of working abrasive grains.

[0020]

[Function] A large number of uniform fine protrusions having a height of several nm to several tens nm and an existing density of several thousand / mm2 to several hundred thousand / mm2 are formed on a magnetic disk substrate. Magnetic head is C
During SS, it comes in contact with the slider surface of the head and receives the head load. Further, it has an effect of holding the lubricating film applied on the surface of the magnetic disk and also preventing adhesion to the magnetic head. Furthermore, since a large number of fine protrusions are in contact with the head slider surface, the surface pressure of each fine protrusion is reduced, so that the change of the fine protrusions by repeating CSS, that is, deformation and wear are small, and the surface of the initial state is small. Maintain properties. Further, the height of the fine protrusion is several nm to several tens of nm, which is very small with respect to the floating gap of the magnetic head (gap between the magnetic head and the surface of the magnetic disk in a steady state) of 150 to 250 nm. The magnetic head floats with a sufficient margin even when considering the assembly accuracy, rotation accuracy and flying fluctuation of the magnetic head, and no head crash occurs due to collision of the magnetic head.

Accordingly, the protective film and the lubricating film having a thickness of several nm formed on the surface of the magnetic disk are hardly worn or damaged, the head does not stick, and the tangential force of the head due to the repetition of CSS does not increase. Thus, a magnetic disk having high reliability with respect to head flying characteristics and sliding resistance can be obtained.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. The present invention provides Ni-P plating with a thickness of 10 μm,
After smooth polishing to a surface roughness of 2 to 3 nm Ra or less, the groove shape is measured with a polishing tape as shown in FIG. As shown in the figure, the height of the fine protrusions formed on the shoulders of the fine grooves is uniform from several nm to several tens of nm, and the existing density is 2000 to 3000 pieces / mm2. 130 mm Al disk.

On this substrate, a thickness of about 50 as shown in FIG.
0 nm Cr-based nonmagnetic metal film 31 and a thickness of about 60 n
Then, a Co-Ni-based magnetic medium 32 of m m was formed by sputtering, and a carbon protective film 33 and a lubricating film 34 having a thickness of about 50 nm were further formed.

The surface shape of the magnetic disk manufactured in this manner is almost the same as the shape on the substrate as shown in FIG. 19, and has a surface roughness of 5.5 nm Ra (5.3 nm Ra on the substrate) and a fineness. The height Rp of the protrusion was 19 nm (20 nm), and the existence density was almost the same.

As a result of a flying test on this magnetic disk with a head floating gap of 0.2 μm, no contact between the head and the disk surface was detected, and good flying characteristics were exhibited.
The surface shape of the magnetic disk was hardly changed by the number of SSs, and the tangential force of the head was hardly increased by the number of CSSs, as shown in FIG. Improved.

As a comparative example, in a magnetic disk having a cross-sectional shape as shown in FIG. 5 in which a fine groove is formed in a base substrate by the conventional technique, the head tangential force increases with the number of CSSs, and the magnetic head may be damaged, and the head may crash. There was a problem. Also, it can be seen that the cross-sectional shape of the disk surface changes significantly with the number of CSSs as compared with the present invention.

Here, one of the manufacturing methods of the above-mentioned substrate is shown in FIG.
Will be described in detail. Electroless Ni-P plating was formed to a thickness of 10 μm, and both surfaces of an Al disk polished and smoothed to a surface roughness of 0.01 μm Rmax or less were surface-processed with a polishing tape of alumina abrasive grains having a grain size of # 3000, and the Ni-P plating substrate surface A fine groove is formed on the substrate.

This surface processing is performed, for example, in Japanese Patent Laid-Open No. 54-23 / 1979.
As shown in Japanese Patent Publication No. 294, a polishing tape is pressed against both surfaces of the substrate shown in FIG. 12 by contact rollers, and while the substrate is being rotated, the polishing tape is wound and the polishing tape slides over the entire surface of the substrate. The substrate is reciprocally slid on the substrate to form fine circumferential or spiral grooves on both surfaces of the substrate. Here, the most important point in forming the fine grooves is to control the pressure applied to the polishing tape being processed with high precision in order to form uniform fine grooves on the underlying substrate. As the fluctuation component of the pressing force, there is an influence of the back tension due to the winding of the polishing tape, and a change in the pressing force due to a shape such as a circumferential undulation or a radial warpage of the disk. Therefore, a parallel leaf spring is used as a pressing means of the contact roller for applying a small pressing force, and a pressing moving means (piezoelectric actuator) for moving the parallel leaf spring in a pressing direction, a pressing force attached to the parallel leaf spring. Measuring means (semiconductor strain gauge) and a control device for controlling the pressurizing and moving means in accordance with the output of the pressing force measuring means are provided. FIG. 21 shows an output waveform obtained by the pressure measuring means including the strain gauges 12 and 13 shown in FIG. 2 when processing is performed at a set pressure of 7.5 N. The output from the force measuring means is
Both sides of the disk, that is, 12 and 13, show 10.5 N at the time of processing, but the back tension 3 N by winding the polishing tape and the pressing force due to the substrate shape, for example, the circumferential waviness and the substrate radial warping. It can be seen that the fluctuation is controlled by the piezoelectric actuator and the actual pressing force during processing is controlled to 7.5N ± 1N. As a result, the cross-sectional shape of the fine groove is controlled so that the height of the fine protrusion from the average surface is 20 to 30 nm, and the frequency of occurrence, that is, the density of the fine protrusion on the substrate surface is about 3000 / mm2. Can be.

Next, on the surface of the substrate, there are several abnormal fine protrusions having a height of 100 nm or more, particularly at the shoulders of deep grooves, which are factors that cause deterioration of the head flying characteristics, and furthermore, head crash accidents. Is a factor. Therefore, FIG.
As shown in Table 2, the surface was processed in the same manner as in the first stage using a polishing tape having a smaller particle size than the above-described first stage polishing tape. As a result of the surface treatment in the second stage, the height of the abnormal fine protrusions was reduced, and the tops of a large number of fine protrusions were normalized, whereby the surface having the cross-sectional shape shown in FIG. 6 could be formed. . Further, between the first stage and the second stage, a means for cleaning the surface of the disk is provided in order to remove dirt on the surface of the disk such as processing chips by the surface processing in the first stage. The configuration of the disk processing apparatus that achieves the processing means described above will be described in detail with reference to the drawings.

FIG. 1 is a front view showing an embodiment of a disk processing apparatus for performing texture processing according to the present invention, FIG. 2 is a plan view showing a main part of the apparatus, and FIG. FIG. 4 is a front view showing details of the means, and FIG. 4 is a side view of the disk cleaning means.

First, the outline of the disk processing apparatus will be described with reference to FIG.
And a pair of contact roller units capable of simultaneously pressing the first polishing tape 4 on both surfaces of the disk 2 with a predetermined pressing force. C, a tape winding motor 7 for winding the first polishing tape 4, and a rocking means W. which can rock the contact roller unit C in the radial direction of the disk 2. A reciprocating means R for reciprocating the contact roller unit C in the radial direction of the disk 2; a first processing head H1 disposed on one side of the disk support; Has the same configuration as the processing head H1, is disposed on the opposite side of the first processing head H1 with respect to the disk support,
Instead of the first polishing tape, a pair of processing heads including a second processing head H2 equipped with a second polishing tape having a smaller abrasive particle diameter than the first polishing tape,
Cleaning the disk, which is disposed between the disk drive motor 3 according to the disk rotating means which can be rotated so that the relative speed with respect to the second polishing tape becomes a predetermined value, and both processing heads; Disk cleaning means S and both processing heads H
1, a disk processing apparatus provided with a controller 17 capable of controlling the disk drive motor 3 and the disk cleaning means S.

Further, the above processing head will be described in detail. The processing head H1 moves the pair of parallel leaf springs 10 and 11 supported by the reciprocating means R so as to be movable in the axial direction of the disc 2 and the parallel wire springs 10 and 11 to form the polishing tape 4. The pressurizing and moving means 23 which eliminates the influence of back tension caused by the winding of the sheet and enables the setting of a predetermined minute pressing force, and responds to minute fluctuations of the pressing force due to the influence of the accuracy of the disk shape at the time of disk processing. Pressurizing force correcting means 50 (for example, a piezoelectric actuator or the like) that performs good correction, and is attached to the parallel leaf springs 10 and 11, is installed on both sides of the disk, and has a center axis directed in the radial direction of the disk 2. A polishing tape driving device 7 attached to the contact rollers 8 and 9 attached to the reciprocating means R and sliding the polishing tape 4 between the disk and the contact roller; A stress measurement device 12 attached to the 0,11 provided a control device 17 for controlling the pressure movement means 23 and pressure correction means 50 in accordance with the output of the stress measuring means.

Therefore, in this disk processing apparatus, the back tension fluctuation due to the winding of the polishing tape, which is a very small factor of the pressing force, that is, the diameter of the polishing tape wound on the supply and take-up reels is affected by the processing. Changes, and the tension of the tape changes, so that the pressing force fluctuates. This variation is always measured by the stress measuring means 12 and 13, and the parallel leaf springs 10 and 11 are
Is adjusted by the pressing and moving means 23, the pressing force of the contact rollers 8, 9 on the disk 2 can be kept constant regardless of the fluctuation of the tension of the polishing tape. Also, in order to improve the responsiveness of the correction of the pressing force against the fluctuation of the pressing force due to the circumferential undulation of the disk during processing and the radial warpage of the disk, the pressing force of the piezoelectric actuator is improved. The minute pressing force can be corrected with good responsiveness by the correcting means 50. With the above function, it has become possible to form a fine groove with high accuracy.

The first processing head H1 is disposed on one side (the right side in FIG. 1) of the disk support 1, and is provided with the disk 2
Are used to form fine grooves (for example, fine grooves having a depth of about 0.04 μm) on both surfaces. The processing head H1 is disposed on both sides of the disc 2
Rocking means capable of sliding the tape winding motor 7a for winding the first polishing tape mounted on each of the set of contact roller units C from below to above and the contact roller unit C in the radial direction; W and
Reciprocating means R capable of reciprocating in the radial direction. Each of the contact roller units C applies a predetermined pressing force to the contact roller 8 via a parallel leaf spring 10 and a contact roller 8 used to press the first polishing tape 4 against the disc 2. And a strain gauge 12 for detecting a pressing force is adhered to the parallel leaf spring 10. By being displaced in the direction perpendicular to the surface of the plate 2, a pressing force can be applied, and the pressing force correcting piezoelectric actuator 50 can correct a small fluctuation of the pressing force during processing with good responsiveness. Has become. The swing means W includes a swing motor 16 and the swing motor 1.
Crank 5 connecting shaft 6 to first processing head H1
It consists of five. The reciprocating means R transmits the rotation of the reciprocating motor 15 to the first processing head H1 with a screw to reciprocate the processing head.

As described above, the second processing head H2 has the same configuration as the first processing head except that a second polishing tape is mounted instead of the first polishing tape. It is provided on the other side (left side in FIG. 1) of the support, and is used for removing the bulge of the fine grooves formed on both sides of the disk by the first processing head.

Further, the configuration of the processing head will be described in detail with reference to FIGS. 2 (a) and 2 (b). Reference numeral 1 denotes a rotating shaft for mounting a disk, which is installed horizontally, 2 a disk as a workpiece, 3 a drive motor for rotating the rotating shaft, 21 a rotatably supported screw, and 15 a screw 21 A reciprocating motor 22 for rotating the motor is a reciprocating carriage supported movably in the radial direction of the disk, that is, in the direction of arrow A. The reciprocating carriage 22 is provided with a female screw. Screw 21
, And the screw 21 and the motor 15 constitute a reciprocating means R. Reference numeral 23 denotes a moving body supported by the reciprocating carriage 22 so as to be movable in the direction of arrow A, and 16 denotes a reciprocating carriage 22
The moving body 23 is vibrated by the vibration device 16 at a minute amplitude. Reference numeral 24 denotes a screw rotatably supported by the moving body 23, 14 denotes a pressurizing motor for rotating the screw 24, and 10 and 11 enable the moving body 23 to move in the axial direction of the disk 2, that is, in the direction of arrow B. A pair of supported parallel leaf springs is provided with a female screw on the support base 51 of the parallel leaf springs 10 and 11, and the female screw is screwed to the screw 24, and is pressed and moved by the screw 24 and the motor 14. Means. In addition, when the circumferential undulation or the radial warpage of the disk is poor, the pressing force fluctuates during processing. For this reason, the parallel leaf springs 10 and 11 are installed on a support table 51 provided with the pressure-compensating piezoelectric actuator 50, and a female screw is provided on the support table 51, and the female screw is screwed to the screw 24 as described above. Reference numerals 8 and 9 denote contact rollers rotatably mounted on the parallel leaf springs 10 and 11, respectively.
Numerals 9 are installed on both sides of the disk 2 and have their central axes mounted in the radial direction of the disk. Reference numerals 18a and 18b denote braking torque motors 5a and 5 attached to the moving body 23.
b is a supply reel attached to the output shafts of the motors 18a and 18b, 7a and 7b are take-up motors attached to the moving body 23, and 6a and 6b are take-up reels attached to the output shafts of the motors 7a and 7b. Reference numerals 4a and 4b denote polishing tapes in which fine abrasive grains such as diamond abrasive grains and alumina abrasive grains are adhered and held to a base material such as a polyester film by a binder such as a resin, and both ends of the polishing tapes 4a and 4b are supply reels 5a and 5b, fixed to the take-up reels 6a, 6b, the motors 18a, 18b, the supply reels 5a, 5b.
b, motors 7a, 7b, and take-up reels 6a, 6b constitute a polishing tape drive, and the polishing tapes 4a, 4b pass between the disk and the contact rollers. 12,
Reference numeral 13 denotes a strain gauge attached to the parallel leaf springs 10, 11, and 17 denotes a control device for controlling the motors 3, 14, 15, and the like. The control device 17 controls the motor 14 and the load in accordance with the outputs of the strain gauges 12, 13. The pressure compensating piezoelectric actuator is controlled to move the parallel leaf springs 10 and 11.

The disk cleaning means includes a rotary scrubber (made of brush or sponge) for simultaneously cleaning both surfaces of the disk, a scrubber drive motor for rotating the rotary scrubber, and a rotary scrubber between a broken line position and a solid line position. And an air cylinder (not shown) that can be reciprocated with the liquid tank, and a liquid tank.

Reference numeral 60 denotes a supply unit for supplying a processing liquid and a cleaning liquid.

An embodiment of texture processing by the disk processing apparatus configured as described above and embodiments of magnetic disk characteristics for a magnetic disk using the textured base substrate will be described.

First, a texture processing method will be described. Attach the disc to the disc support. The control device has the first
Set processing conditions such as pressure, relative speed, vibration amplitude, and number of reciprocations.

Here, when the disk processing device is turned on, the disk is rotated by the motor 3, and at the same time, the first processing head is rocked by the rocking motor at the set rocking amplitude. The polishing tapes 4a and 4b are wound up with a constant force, the pressure applied to the disc is adjusted so as to become the set first pressure, and the reciprocating carriage 22 is moved by the reciprocating means R.
Is reciprocated, fine grooves are formed on the surface of the disk 2 by the polishing tapes 4a and 4b. During this time, the rotation speed of the disk 2 is adjusted by the disk drive motor 3 so that the relative speed between the disk 2 and the first polishing tape 4 becomes the set first relative speed. In this way, while the processing is in progress, the processing liquid is continuously supplied from the supply unit to the disk. Then, even if the tension of the polishing tables 4a and 4b fluctuates and the parallel leaf springs 10 and 11 are deformed, the control device 17 responds to the output of the strain gauges 12 and 13; Since the motor 14 is controlled according to the amount, the parallel plate springs 10 and 11 apply the pressing force of the contact rollers 8 and 9 to the disk 2 regardless of the fluctuation of the tension of the polishing tapes 4a and 4b according to the deformation amount. Since the pressure can be kept constant, a small pressing force can always be maintained, and thus a small and uniform fine groove can be formed. Further, with respect to the fluctuation of the pressing force caused by the rotation of the disk 2 and the fluctuation of the pressing force caused by sliding the processing head in the radial direction of the disk 2, that is, the circumferential undulation of the disk 2. The pressurizing force fluctuates due to the influence of the straightness and the warp in the radial direction and the warp. For these, the amount of fluctuation of the pressurizing force can be immediately corrected by the pressurizing force correcting piezoelectric actuator 50 according to a command from the control device 17. it can.

When the first processing head reciprocates a set number of times, the processing head retreats (moves to the right in FIG. 1) and the supply of the processing liquid stops.

Next, the rotary scrubber 6 located at the position indicated by the broken line
1 rises to the solid line position, and the rotary scrubber 61 is rotated by the scrubber drive motor. The disk 2 also rotates, and the cleaning liquid is supplied from the supply unit 60, and the disk 2 is cleaned. When the cleaning is completed, the rotary scrubber 61 is lowered to the position indicated by the broken line, and the supply of the cleaning liquid is stopped.

Then, the second processing head H2 advances, and the first processing head H2 is moved by this processing head.
The disk 2 is processed in the same manner as in 1. That is, at the same time that the disk is rotated by the motor 3, the second machining head H
2 is oscillated by the oscillating motor at the set oscillating amplitude, and the polishing tape driving device winds the polishing tapes 62a and 62b with a constant force so that the pressure applied to the disc becomes the set second pressure. Reciprocating carriage 6 adjusted by reciprocating means
3 reciprocates, the fine protrusions existing on the surface of the disk 2 are removed by the polishing tapes 62a and 62b and smoothed. During this time, the rotation speed of the disk 2 is adjusted by the disk drive motor 3 so that the relative speed between the disk 2 and the second polishing tape becomes the set second relative speed. While the processing is in this way, the processing liquid is continuously supplied from the supply unit 60 to the disk. When the second processing head H2 reciprocates by the set number of reciprocations, the processing head retreats (moves to the left in FIG. 1), and the supply of the processing liquid stops. Finally, when the disk 2 is cleaned by the disk cleaning means 64 in the same manner as described above, the disk processing device is turned off. If you remove the disk 2 from the disk support 1,
A desired fine groove is formed. Further, if a magnetic medium, a protective film, and a lubricating film are formed, a magnetic disk having excellent sliding resistance can be obtained.

Next, a specific example will be described.

A specific example in which fine grooves are formed in a disk 2 which is Ni-P plated to a thickness of about 10 μm on an Al disk will be described with reference to FIGS.

FIG. 5 is an enlarged sectional curve diagram showing an example of the surface properties of a disk processed by the first processing head of the disk processing apparatus shown in FIG. 1, and FIG. 6 is further processed by the second processing head. FIG. 4 is an enlarged cross-sectional curve diagram showing an example of the surface properties of a circular disc.

The first polishing tape was made of Al 2 O 3 having a particle size of 3 μm.
Abrasive grains, first pressure 4N, first relative speed 4m / s
ec, the disk 2 was processed by the first processing head H1 while supplying a water-soluble cutting fluid with the swing amplitude being 1 mm, and the surface of the disk 2 was deepened as shown in FIG. A fine liquid having a height V of about 40 nm was formed, but a swelling (fine projection) height H of about 30 nm and a swelling ratio H / V
> 0.5. Also, the height of the swell was uneven.

Second polishing tape Al2 having a particle size of 0.5 μm
O3 abrasive grains, second pressure 2N, second relative speed 8m
/ Sec, the amplitude of oscillation was 1 mm, and the disk 2 washed with pure water was processed by the second processing head H2 while supplying a water-soluble cutting fluid. As shown in the figure, the depth V of the fine liquid is maintained at about 40 nm, the height of the swell is reduced to about 10 nm or less, the variation is small, the swell ratio H / V is about 0.25, and the desired fineness is obtained. A groove was obtained.

According to the above-described embodiment, since the first processing head attempts to delete only the swelling portion generated on the shoulder of the fine groove, the fine groove depth V is 20 to
100 nm, the ratio of the swelling (fine protrusion) height H to H
There is an effect that a smooth surface of /V≦0.5 can be formed. Further, by changing the processing conditions such as the particle size of the polishing tape, the abrasive material, the number of reciprocal sliding on the disk, and the pressing force, an arbitrary fine groove can be formed.

By using this method, a non-magnetic metal film 31, a magnetic medium film 32, a carbon protective film 33, and a lubricating film 34 are formed on the substrate 30 as shown in FIG. The thin-film magnetic disk 2 thus obtained has good head flying characteristics and extremely excellent reliability and stability.

Various characteristics of the thin-film magnetic disk in which the fine grooves according to the present invention are formed will be described in detail below along with comparative examples. That is, a disk having a height of the fine protrusions of several nm to several tens of nm and a frequency of the fine protrusions of several thousand / mm2 to several hundred thousand / mm2,
A comparison with other disks is shown. 13 and 14
In addition, texture processing is performed by changing the processing conditions such as the grain size of the polishing tape, the number of reciprocations of the processing head, the pressing force, etc., and the same non-magnetic metal Of thin film magnetic disk with magnetic film, magnetic medium film, carbon protective film and lubricating film formed on head flying characteristics, head adhesion, deformation of surface texture (fine protrusion) by CSS test, and head tangential force The results of examining the effects are shown. The height of the fine protrusion is several nm (2 to 3 n
m) Below, for example, in the case of an undersubstrate close to the polished surface, the head floating characteristics are good, but the tangential force of the head increases, causing a problem of head adhesion, damage to the gimbal supporting the head, and rotation of the disk. An accident occurred in which the motor was overloaded and the disc could not be rotated. In addition, the height of the fine protrusion is several tens nm or more,
For example, when the fine protrusion is 90 nm or more, the head tangential force is small and the problem of head sticking does not occur, but the head floating characteristics are poor and a head crash accident occurs.

The density of the fine protrusions is several thousand / mm 2
Hereinafter, for example, in the case of 110 pieces / mm 2, the surface pressure of each fine protrusion due to the head load is large, the sliding wear of the fine protrusion by the head is remarkable with the CSS frequency, and the lubricant and the carbon protective film are greatly damaged. In other words, when the number of CSS times was 2000 to 3000 times or less, a head crash occurred. Further, when the existence density is more than several hundred thousand / mm 2, for example, 300,000 / mm 2, the contact area between the magnetic head and the disk surface is large, the head adhesive force at the start of CSS becomes large, The support gimbal was damaged and the disk rotation drive motor was overloaded, causing an accident that the disk could not rotate.

In the above embodiment, a method of forming fine grooves and fine protrusions using a polishing tape has been described, and the advantages of various characteristics of a thin-film magnetic disk using this base substrate have been shown. The same effect can be obtained by a surface processing method such as cutting, grinding, lapping, and polishing, a surface treatment method such as etching and sandblasting, and a pattern forming method of a dry process. Further, as an embodiment of the present invention, the width of the polishing tape uses a polishing tape narrower than the width of the processing surface of the disk, a contact roller pressing the polishing tape reciprocates in the radial direction of the disk, Although the disk surface was processed while swinging, the width of the polishing tape was approached to the width of the surface to be processed of the disk, or a polishing tape with a width larger than the width of the surface to be processed was used. The same effect can be obtained by swinging in the radial direction, or by processing a disk without swinging.

As another application example of the present invention, the method and apparatus for processing a disk according to the present invention are applied to a protective film surface of a thin-film magnetic disk. That is, after texturing a Ni-P plated disk of the base substrate, a non-magnetic base film, a magnetic medium, and a carbon protective film are formed by sputtering.
In this process, fine projections such as fine deposits are formed on the surface. In order to remove these fine protrusions without affecting the base such as a magnetic medium and to smooth the surface, it is possible to set a small pressing force, and always apply a small pressing force while processing the disk. Need to be controlled. Therefore, a disk processing apparatus using the polishing tape according to the present invention is required.

A specific example will be described below.

FIG. 22 shows Ni having an outer diameter of 130 mm and an inner diameter of 40 mm.
-Co-Ni plating on the polished substrate
Before performing the above-mentioned surface finishing on the thin film magnetic disk on which the magnetic protective medium and the carbon protective film are formed by sputtering, the flying height of the floating magnetic head equipped with the piezo element is set to 0.15.
FIG. 23 is a graph showing the output of a piezo element when the levitation test was performed with μm. FIG. 23 shows the polishing of the above magnetic disk by the disk finishing apparatus shown in FIGS. The tapes 4a and 4b have a diameter of 0.5 μm of diamond abrasive grains, the pressure applied to the magnetic disk 2 by the rubber elastic contact rollers 8 and 9 is 2N, the rotational speed of the magnetic disk is 1000r / min, and the reciprocating sliding of the processing head. It is a graph which shows the output of the above-mentioned piezo element at the time of performing finishing processing on the processing conditions that the number of times of movement is five times. As is clear from these graphs, the output of the piezo element due to the fine protrusions T having a height of 0.15 μm or more is present on the magnetic disk 2 before finishing, as shown in FIGS. Since the magnetic disk 2 after finishing processing by the disk finishing device does not have a fine protrusion having a height of 0.15 μm or more, it can be seen that the fine protrusion is removed.

Further, as a method of accurately removing the fine protrusions on the surface of the magnetic disk, the position of the contact roller to which the polishing tape is added on the magnetic disk is determined by a linear scale provided on the reciprocating means of the processing head. The disk rotation motor was controlled so that the relative speed between the polishing tape and the disk surface was always constant. By this effect, the influence of the dynamic pressure due to the abrasive interposed between the polishing tape and the disk surface in the texturing becomes uniform over the entire surface of the disk. Therefore, the entire surface of the disk can be finished with a uniform pressing force, the effect of removing the fine projections becomes uniform, and a highly accurate disk can be obtained.

As described above, when the present invention is applied to the protective film surface of a thin-film magnetic disk, a minute pressing force can be uniformly applied to the surface of the disk. The protrusions can be removed by minute amounts, without damaging the magnetic medium around the minute protrusions.
The minute protrusion can be reliably smoothed. In addition, since diamond abrasive grains are adhered and held to the base material of the polishing tapes 4a and 4b by a binder such as a resin, when an extremely large impact force is applied, the impact force is reduced by the binder and the soft contact roller. Therefore, the magnetic medium other than the minute protrusion is not destroyed.

Regarding the polishing tape used in the present invention, fine grooves are accurately formed, and the height of the fine protrusions is set to several nm to several tens n.
In order to stably form m, the frequency of several thousand pieces / mm 2 to several hundred thousand pieces / mm 2, a polishing tape having uniform cutting edge abrasive grains is required.

A conventional polishing tape is shown in FIG.
Fine abrasive grains 65 are dispersed in a resin 66, applied to a polyester film 67, and heat-treated. The cross-sectional shape has large irregularities, and the effective abrasive grain cutting edge that contributes to surface processing is unstable. For this reason, as shown in FIG. 25, the surface of the conventional polishing tape is subjected to truing and dressing of the polishing tape so that the tip of the abrasive on the surface of the polishing tape has an unevenness of the abrasive grain tip within 50 nm. The working abrasive density was uniformly corrected so as to be several tens to several hundreds / mm 2. Further, a method of truing and dressing the polishing tape will be described in detail with reference to FIG. The polishing tape 70 is wound by a polishing tape winding motor 74 while being sandwiched between a dresser 71 having diamond abrasive grains fixed to a cylindrical surface and a roller 72 having a surface of a soft material for backup. At this time, a polishing tape whose surface is modified is supported and supplied to the output shaft of the braking torque motor 73 in order to make the tape tension uniform. Dresser 71
A piezoelectric sensor 76 is provided on the rotating shaft of the roller 72 to control the applied pressure. With this polishing tape repair device, the abrasive layer on the polishing tape surface becomes flat, the variation in the number of effective working abrasive grains can be reduced, and the accuracy of the fine grooves and fine protrusions on the textured surface can be improved. did it. 75
This shows a method of truing and dressing other polishing tapes.This is a self-correcting dressing method in which the surface of the polishing tape is dressed by sliding the surface of the polishing tape on the same polishing tape. The same result as described above can be obtained by this method in which the pressure is applied to the roller.

For this reason, the tip of the abrasive grains on the surface of the conventional polishing tape was uniformly corrected by polishing tape truing and dressing shown in FIG. Also, by controlling the abrasive particle size of the polishing tape and controlling the dressing conditions of the polishing tape, the frequency of the fine protrusions can be controlled in the range of several thousand / mm2 to several hundred thousand / mm2. Was.

[0063]

As described above in detail, according to the present invention, a disk processing method capable of forming a highly precise fine groove having a very small fine protrusion on a Ni-P plating base substrate, and this method. Can be provided for use directly in the implementation of

Further, in this disk processing apparatus, by using a parallel leaf spring, a strain gauge, and a pressing force correcting piezoelectric actuator, the pressing force of the contact roller against the disk is extremely small, regardless of the accuracy of the disk shape. ,
Since it can be made uniform at all times, stable and uniform fine grooves can be formed over the entire surface of the disk, and fine protrusions of the fine grooves formed on the Ni-P plating base substrate are removed little by little. It can be smoothed with high precision.

Further, the micro-protrusion control disk processing apparatus can cut and remove minute projections on the surface of the carbon protective film by minute amounts so that the fine projections can be reliably removed. The surrounding carbon protective film and the surface forming film such as the magnetic medium are not damaged. Therefore, it is possible to obtain a very high smooth surface with good surface accuracy.
As described above, according to the disk processing apparatus and method of the present invention, the surface having a height of n
Since fine protrusions of m to several tens of nm are uniformly formed at a frequency of several thousand / mm <2> to several hundred thousand / mm <2>, the magnetic head repeatedly intermittently contacts the disk surface. The load is received by the above-mentioned many fines, the surface pressure at each fine projection is small, and the deformation and sliding wear of the fine projection are reduced. Further, the protective film and the lubricating film formed on the fine protrusions are less deteriorated, and have an effect of improving the sliding resistance. Also, the height of the fine protrusion is several n
Since it is m to several tens of nm, even if the head floating gap is reduced (for example, 0.15 μm), there is no problem that the magnetic head collides and causes a head crash, and the coating is applied to a film thickness of several nm or less. Head adhesion due to lubrication film,
There is no problem of head sticking due to moisture in the atmosphere.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a disk processing apparatus according to the present invention.

FIG. 2 is a plan view showing a main part of the device.

FIG. 3 is a front view showing details of a disk cleaning unit in FIG. 1;

FIG. 4 is a side view of the disk cleaning means.

FIG. 5 is an enlarged sectional curve diagram showing an example of the surface of a disk processed by a first processing head of the disk processing apparatus according to FIG. 1;

FIGS. 6A and 6B are enlarged cross-sectional curves showing an example of the surface of a disk further processed by a second processing head.

FIG. 7 is a front view showing a conventional disk processing apparatus for forming fine grooves.

FIG. 8 is a side view of the device.

FIG. 9 is a cross-sectional configuration diagram of a thin-film magnetic disk using a base substrate of the present invention.

FIG. 10 is a cross-sectional configuration diagram of a thin-film magnetic disk according to the related art.

FIG. 11 is a cross-sectional shape of a fine groove.

FIG. 12 is an explanatory view of a conventional disk processing apparatus.

FIG. 13 shows an example of a result obtained by examining the height and existence density of a fine protrusion and characteristics of a magnetic disk.

FIG. 14 shows an example of a result obtained by examining the height and existence density of a fine protrusion and characteristics of a magnetic disk.

FIG. 15 shows a surface obtained by measuring a minute change on the order of nanometers of a disk surface by CSS with a high-resolution SEM and expressing the change in the cross-sectional shape of the surface, and (a) is a cross-sectional shape before CSS; (B) shows a cross-sectional shape after CSS.

FIG. 16 shows an Abbott load curve on the extreme surface of the disk before and after CSS.

FIG. 17 shows the peak count distribution on the outer surface of the disk, that is, the density of fine protrusions.

FIG. 18 is a view showing a groove shape of a disk.

FIG. 19 is a sectional view of the surface of a magnetic disk in which a magnetic medium is formed on the disk shown in FIG. 6B according to the present invention.

FIG. 20 shows CSS characteristics, and shows a comparison between the present invention and the related art regarding the relationship between the number of CSS times and the head tangential force.

FIG. 21 shows an output from a strain gauge showing a control of a small pressing force according to the present invention, and detects and sets an actual pressing force at the time of processing in consideration of the influence of back tension caused by winding a polishing tape. Indicates that the pressure is accurately controlled.

FIG. 22 is a result of examining head flying characteristics of a disk before and after the application of the present invention, and shows an output of a piezo element by a floating magnetic head equipped with a piezo element before applying the present invention. Graph.

FIG. 23 shows the results of examining the head flying characteristics of a disk before and after the application of the present invention, showing a case after applying the present invention.

FIG. 24 is a cross-sectional structure of a conventional polishing tape.

FIG. 25 is a cross-sectional structure of the polishing tape of the present invention.

FIG. 26 is a schematic view of a dressing and truing apparatus for a polishing tape for producing the polishing tape of the present invention.

FIG. 27 is an explanatory diagram illustrating a relationship between a cross-sectional shape of a textured surface and an Abbott load curve, and illustrating a correlation with CSS characteristics.

FIG. 28 is an explanatory diagram illustrating a relationship between a cross-sectional shape of a textured surface and an Abbott load curve, and illustrating a correlation with CSS characteristics.

FIG. 29 is an explanatory diagram showing a fine projection in a cross-sectional shape of a textured surface.

FIG. 30 is a view for explaining an Abbott load curve representing the properties of the cross-sectional shape of the textured surface.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating shaft for disk mounting, 2 ... Magnetic disk (disk), 3 ... Disk drive motor, 4a, 4b ... Polishing tape, 5a, 5b ... Supply reel, 6a, 6b ... Take-up reel, 7a, 7b ... winding motor, 8,9 ... contact roller, 10,11 ... parallel leaf spring, 12,13 ... strain gauge, 14 ... pressing motor, 15 ... reciprocating motor, 17 ... control device, 18a, 18b ... Control torque motor, 21: screw, 22: reciprocating carriage, 24
... Screws, 50 ... Pressure compensation piezoelectric actuators,
Reference numeral 60: base substrate, 61: fine groove, 62: non-magnetic metal film, 63: fine protrusion, 64: magnetic medium, 65
... protective film, 66 ... lubricating film.

Claims (1)

[Claims] 1. A magnetic disk having a magnetic film formed on an underlying substrate, wherein a height of a fine projection having a flat portion is several nm to 10 nm in a sectional shape of a surface.