JPH033765A - Processing method for surface of rigid substrate - Google Patents

Abstract

PURPOSE:To uniformize the roughness of the rigid substrate surface over the inner peropheral part from the outer peripheral part in a short time by one polishing, by rotating the polishing roll of a deformed roll and rigid substrate and making the relative speed of the both about constant over the inner peripheral part from the outer peripheral part of this substrate. CONSTITUTION:A deformed roll whose outer diameter R1 of the part abutting on the inner peripheral part 6a of a rigid substrate to be subjected to surface treatment is made larger than the outer diameter R2 of the part abutting on the substrate outer peripheral part 7a is used as a polishing roll 8. When this polishing roll 8 and rigid substrate 7 are rotated at the specific rotation speed, the relative speed of the both 7, 8 becomes about constant over the inner periph eral part 6a from the outer peripheral part 7a of the rigid substrate 7. Conse quently, the surface roughness in the peripheral direction of the rigid substrate 7 surface becomes almost uniform over the inner peripheral part 6a from the outer peripheral part 7a of this substrate 7 by polishing once.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for surface treatment of a rigid substrate used as a support for a so-called rigid disk (hard disk).

[Summary of the invention]

In the present invention, when surface treatment is performed by bringing a polishing roll into contact with the surface of a disk-shaped rigid substrate, the outer diameter of the portion that contacts the inner periphery of the substrate is larger than the outer diameter of the portion that contacts the outer periphery of the substrate. The surface roughness of the surface of the rigid substrate can be improved in a short time by using a polishing roll with a diameter roll and keeping the relative speed of the rigid substrate and the polishing roll substantially constant from the outer circumference to the inner circumference of the substrate. The objective is to make the temperature uniform from the outer circumference to the inner circumference.

[Prior Art] For example, disk-shaped magnetic disks that can be randomly accessed are widely used as storage media in computers, etc. Among them, aluminum is used as a substrate because of their excellent responsiveness and high storage capacity. A magnetic disk using a rigid substrate made of an alloy material or the like, a so-called rigid disk, is used as a fixed disk or an external disk.

By the way, in the above-mentioned rigid disk, it is generally required that the surface of the rigid substrate before the formation of the magnetic layer has a predetermined surface roughness due to fine irregularities from the viewpoint of running performance and durability. surface treatment is being carried out. Similarly, in the case of reproducing a defective rigid disk, it is necessary that the surface of the rigid substrate after the magnetic layer is removed has a predetermined surface roughness, and thus surface treatment is performed. Conventionally, in order to perform surface treatment on a rigid substrate, for example, as shown in FIG. (3) are brought into contact with each other at a predetermined pressure P, , P, and the rigid substrate (1) and the polishing roll (3) are rotated so that the polishing roll (3) forms fine particles on the surface of the rigid substrate (1). A method is known in which unevenness is formed. The polishing roll (3) may be a grindstone, a cylindrical rubber roll, or a rubber roll wrapped with a ramping tape or the like.

By the way, since the roll length l of the polishing roll (3) is larger than the radius difference between the outer diameter and the inner diameter of the rigid substrate (1), the rigid substrate (1) can be polished to -degrees. I can do it. However, when trying to polish the rigid substrate (1) to -degrees, the rigid substrate (1) and the L roll (3)
The relative speed of the rigid substrate (1) differs greatly between the outer circumference and the inner circumference, and becomes faster toward the outer circumference. As a result, the surface roughness at the inner periphery of the rigid substrate (1) becomes greater than the surface roughness at the outer periphery, which reduces the reliability of the disk, especially C.
The 3S characteristics (contact start/stop characteristics) tend to deteriorate toward the outer periphery. In this case, the pressure applied to the rigid substrate (1) by the grindstone (3) is P, , P
Although it is possible to make the surface roughness uniform by changing the pressure PP2 between the inner and outer circumferences of the rigid substrate (1), it is difficult to control the pressure PP2 applied to the rigid substrate (1).

Therefore, conventionally, as shown in Fig. 4, a polishing roll (
4) Roll length! 2 to be about 1/3 to 1/4 of the radius difference between the outer diameter and the inner diameter of the rigid substrate (5), and move this polishing roll (4) in the radial direction, and By changing the rotation speed of the rigid substrate (5) according to the position, the relative speed between the polishing roll (4) and the rigid substrate (5) can be varied from the outer circumference to the inner circumference of the substrate (5). A surface treatment method has been proposed in which polishing is performed at a substantially constant rate.

However, in the above method, the surface roughness of the rigid substrate surface is approximately uniform from the outer circumference to the inner circumference of the substrate (5).
However, it takes a lot of processing time and is not suitable from the viewpoint of productivity. Further, in this case, a mechanism for moving the polishing roll (4) is required, which causes problems such as a complicated structure.

[Problem to be solved by the invention]

In this way, in surface treatment of a rigid substrate, from the viewpoint of processing time, it is ideal to perform the surface treatment in one polishing process using a polishing roll that is longer than the difference in radius between the outer diameter and the inner diameter of the rigid substrate. This creates a problem of uniform surface roughness, and on the other hand, when surface treatment is performed by moving the polishing roll in the radial direction of the rigid substrate, problems arise in terms of surface treatment time and the use of complicated mechanisms.

Therefore, the present invention has been proposed in view of the conventional situation, and it is possible to uniformize the surface roughness of the surface of a rigid substrate from the outer circumference to the inner circumference in a short time and in a simple manner. The object of the present invention is to provide a method for surface treatment of a rigid substrate, which can perform surface treatment using a mechanism that allows for surface treatment.

[Means to solve the problem]

The present invention has been proposed to achieve the above-mentioned object, and when surface treatment is performed by bringing a polishing roll into contact with the surface of a disk-shaped rigid substrate, the polishing roll is brought into contact with the inner peripheral portion of the substrate. The outer diameter of the portion is larger than the outer diameter of the portion that contacts the outer periphery of the substrate, and the rigid substrate and polishing roll are rotated to adjust the relative speed of the rigid substrate and the polishing roll to the outer periphery of the substrate. It is characterized in that it is substantially constant over the inner circumferential portion.

[Effect]

In the present invention, when surface-treating the surface of a rigid substrate, a different diameter roll is used as a polishing roll, in which the outer diameter of the portion that contacts the inner periphery of the substrate is larger than the outer diameter of the portion that contacts the outer periphery of the substrate. Therefore, if the rigid substrate and the polishing roll described in 2 are rotated at a predetermined rotational speed, the relative speed between the rigid substrate and the polishing roll changes from the outer circumference to the inner circumference of the substrate without moving the polishing roll in the radial direction. It remains approximately constant throughout the area.

Therefore, the surface roughness in the circumferential direction of the surface of the rigid substrate becomes approximately uniform from the outer circumferential portion to the inner circumferential portion of the rigid substrate by the polishing process of -degree.

〔Example〕

Hereinafter, specific embodiments to which the present invention is applied will be described with reference to the drawings.

The method for surface treatment of a rigid substrate of this embodiment is to form fine irregularities on the surface of a disk-shaped rigid substrate by bringing a polishing roll into contact with the surface of the rigid substrate.

To form fine irregularities on the surface of a rigid substrate, first
As shown in the figure, a rigid substrate (7) having a spindle shaft mounting hole (6) in the center for mounting a spindle shaft of a magnetic recording/reproducing device is mounted on a substrate rotation drive device (not shown).

The rigid substrate (7) used here is a so-called rigid disk substrate on which a magnetic layer is not formed, such as a rigid disk used as a storage medium in computers and the like. Examples of this type of rigid substrate (7) include aluminum plates, aluminum alloy plates, N1-P plated aluminum plates, aluminum alloy plates, alumite-treated aluminum plates, aluminum alloy plates, glass plates, and polyester plates. Plastic substrates made of materials such as etherimide, polycarbonate, polysulfone, polyethersulfone, polyacetal, and polyphenylsulfide can also be used.

Next, the polishing roll (8) is applied to the surface of the rigid substrate (7).
are brought into contact with each other at a predetermined pressure P.

As shown in Fig. 2, the polishing roll (8) is made of a grindstone formed into a predetermined shape, for example, and is physically attached to a rotating shaft (9) that is rotated by a drive such as a morph. Fixed. In addition to the grindstone, for example, a hard rubber roll or a roll made of a material rich in elasticity may be used as the polishing roll (8). In the polishing process in this case, it is necessary to drop free abrasive grains in the form of a slurry onto the surface of the rigid substrate (7) for til+ polishing. Of course, even when using a grindstone, it is desirable to polish while dropping free abrasive grains.

The polishing roll (8) has an outer diameter R1 of a portion that contacts the inner periphery of the substrate larger than an outer diameter R2 of the portion that contacts the outer periphery of the substrate, and the diameter is larger at the outer periphery of the substrate than at the inner periphery of the substrate. The diameter of the roll is gradually reduced towards the end. That is, the polishing roll (8) is attached to the rigid substrate (7).
Let the inner diameter of ψ1. The outer diameter is ψ2. When the rotation speed of the rigid substrate (7) is N (rpm), the polishing roll (8) at the inner peripheral edge (6a) of the spindle shaft mounting hole (6)
The outer diameter R1 of the polishing roll (8) and the outer diameter R2 of the polishing roll (8) at the outer peripheral edge (7a) of the rough plate (7) are expressed by the formula (]) and the formula (2), respectively, R, = -ψ2...( ]) Formula R2−□ψi ・ ・ ・Formula (2) (however, n>
It is O. ).

Further, the rotation speed N' of the polishing roll (8) is N'=
The relationship is n N (rpm). Furthermore, the length of the slope of the polishing roll (8)! ! 3 is a length that can cover at least the range that requires polishing (effective magnetic recording area range), and especially when reproducing a rigid substrate of a defective rigid disk, 3≧(
It is desirable that the relationship is ψ2−ψ1)/2.

In this embodiment, the inner diameter of the rigid substrate (7) is ψ1.
Although the outer diameter is ψ2, the inner diameter ψ1 and the outer diameter ψ2 may be at least the inner diameter and outer diameter at positions corresponding to the innermost and outermost parts of the range that requires polishing.

Next, the polishing roll (8) formed as described above is
The rigid substrate (7) and the polishing roll (8) are rotated so as to have a relationship such that ' = n N (rpm).

At this time, the polishing roll (8) is rotated in a direction (direction C in FIG. 1) toward the rotation direction (direction C in FIG. 1) of the rigid substrate (7), and It is desirable to swing the rigid substrate (7) in the radial direction (direction C in FIG. 1) with a predetermined amplitude.

Then, the relative speed between the rigid substrate (7) and the polishing roll (8) becomes substantially constant from the outer circumference to the inner circumference of the rigid substrate (7). Therefore, if these relative speeds are approximately constant, the substrate will be polished from the outer periphery to the inner periphery under the same conditions, and as a result, the periphery will be polished from the outer periphery to the inner periphery of the substrate. The surface roughness in the direction becomes uniform.

Here, the surface treatment of the rigid substrate was actually performed based on the following conditions.

First, an aluminum substrate with a diameter of 5.25 inches (outer diameter ψ 213 mm, inner diameter ψ 145 mm) with N1-P plating applied to the surface was used as the rigid substrate (7), and this was rotated at a rotation speed of N = 10 Orpm. Rotate. On the other hand, a WA grindstone (white fused alumina grindstone) with a grain size of #4000 is used for the polishing roll (8), and it is rotated at a rotation speed of N'=200.
rpm in the direction of rotation of the rigid substrate (7). At this time, since the relationship is N'-nN, n is 2. Therefore, the rigid substrate (7) at this time
The outer diameter R1 of the polishing roll (8) at the inner diameter ψ1 position of the polishing roll (8) and the polishing roll (
The outer diameter R2 of 8) is 65 mm and 22.5 mm, respectively, from equations (1) and (2) above. The slope length 13 of the polishing roll (8) is the outer diameter ψ2 of the rigid substrate (7).
The diameter was set to 53 mm, which is larger than 1/2 of the difference between the inner diameter and the inner diameter ψ1.

Then, the polishing roll (8) configured as described above is brought into contact with the surface of the rigid substrate (7) under a pressure of 7 kg, and the polishing roll (8) and the rigid substrate ( 7) was rotated and polished for 30 seconds.

At this time, the polishing roll (8) is rotated with an amplitude], 5
Polishing was performed by dropping free abrasive grains in the form of a slurry onto the surface of the rigid substrate (7) while shaking the substrate in the radial direction at a speed of 60 mm1 per minute.

Next, the surface roughness of the polished rigid substrate (7) surface was measured. Note that the surface roughness was determined and evaluated as the center line average roughness Ra.

As a result, the surface roughness Ra2 of the outer periphery of the rigid substrate (7) and the surface roughness Ra of the inner periphery of the rigid substrate (7) are both R
a2''iRal = 2.23 nm to 2.25 nm.

Next, as Comparative Example 1, as shown in FIG. 3, the roll length is longer than the difference in radius between the outer diameter and inner diameter of the rigid substrate (1)! , using a cylindrical polishing roll (3) with a rigid substrate (1).
I tried polishing the surface.

The same substrate used in the previous experiment was used as the rigid substrate (1), and was rotated at a rotational speed of 200 (rpm). Then, a polishing roll (3) around which a wrapping tape of #4000 particle size was wound was applied to the polishing roll (3) under a pressure of 0.7 k.
The rotation speed of the polishing roll (3) is 0 while contacting with
．． It was rotated at 5 rpm. At this time, polishing was performed for 30 seconds while swinging the polishing roll (3) in the radial direction of the substrate 60 times per minute at an amplitude of 1.5 +++I11.

Then, as in the previous experiment, a rigid substrate (1) after polishing was prepared.
The surface roughness of the surface was measured.

As a result, the surface roughness Ra of the surface of the rigid substrate (1) was L7 nm at the outer circumference and 2.5 nm at the inner circumference.

Furthermore, as Comparative Example 2, as shown in FIG.
, 2 was used to polish a rigid substrate (5) that was the same as the rigid substrate used in the experiment described above.

That is, roll length I! 220mm polishing roll (4)
is reciprocated in the radial direction of the rigid substrate (7) from the outer periphery to the inner periphery and from the inner periphery to the outer periphery, and the rigid substrate (5) is moved in accordance with the moving position of the polishing roll (4) at that time. Polishing was performed while changing the rotation speed.

At this time, the rotational speeds at the outer circumference and inner circumference of the rigid substrate (5) were 70 rpm and 200 rpm, respectively.

The surface roughness Ra of the polished rigid substrate (5) surface is
2.3n at the outer circumference and inner circumference, respectively.
It was approximately equal to m. However, the time required for the polishing was approximately 3.3 mm to obtain the same level of surface roughness as in the previous experiment.
It took 92 seconds, which is twice as long.

As can be seen from these experiments, according to this experiment, the surface roughness of the rigid substrate surface in the circumferential direction can be made approximately uniform from the outer circumference to the inner circumference of the rigid substrate in a short time. Moreover, the surface treatment can be easily performed without the complicated work as in Comparative Example 2.

The surface roughness can be made uniform from the outer circumference to the inner circumference.

Therefore, if this is used, for example, as a substrate for a rigid disk, runnability and durability can be ensured at any location on the surface of the w plate, making it possible to provide a highly reliable rigid disk.

In addition, in the method of the present invention, it is only necessary to bring the polishing roll, which has a different diameter roll, into contact with the rigid substrate and rotate the rigid substrate and the polishing roll, so the mechanism is simple and easy. The surface roughness of the substrate surface can be made uniform.

〔Effect of the invention〕

As is clear from the above description, in the method of the present invention, the polishing roll and the rigid substrate are rotated using polishing rolls having different diameters, and the relative speed between the rigid substrate and the polishing roll is controlled by the rotation of the polishing roll and the polishing roll. Since it is approximately constant from the outer periphery to the inner periphery, the surface of the rigid substrate can be polished in a short time by -degree polishing.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an example of a polishing roll used to carry out the present invention, and FIG. 2 is an enlarged perspective view showing the polishing roll on an enlarged scale. FIG. 3 is a schematic perspective view showing a conventional polishing roll used for surface treatment of a rigid substrate, and FIG. 4 is a schematic perspective view showing a further conventional polishing roll. 5 7... Rigid substrate 8... Polishing roll 6

Claims (1)

[Scope of Claims] When performing surface treatment by bringing a polishing roll into contact with the surface of a disk-shaped rigid substrate, the outer diameter of the portion of the polishing roll that contacts the inner circumference of the substrate is larger than the outer diameter of the portion that contacts the outer circumference of the substrate. The rigid substrate and the polishing roll are rotated so that the relative speed between the rigid substrate and the polishing roll is substantially constant from the outer periphery to the inner periphery of the substrate. A method for surface treatment of rigid substrates.