JPS62236664A - Texturing method for magnetic disk substrate - Google Patents

Abstract

PURPOSE:To remove lugs generated on the surface of a substrate in the previous process by polishing a magnetic disk substrate with abrasive grains smaller in size than those used in the previous process after applying the process which rotates it and presses a lapping tape to the substrate face with a pressing roller. CONSTITUTION:Abrasive grains smaller in size than those used in the previous process are used in the second process. A tape 3 is pressed to a rotating disk substrate 1 by a rubber roll 2 in the polishing method using the same device as in the first process. A polishing method in which a rotating disk substrate 4 is clamped between polishers 5 held by holding plates 6 or a polishing method in which carriers 8 fitted with disk substrates 7 are clamped between polishers 9 held by holding plates 10 and the holding plates 19 and the carriers 8 are rotated can also be used. According to these methods, lugs generated in the first process can be removed without removing fine grooves on the surface of the substrate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a magnetic disk! The present invention relates to a method for processing a magnetic disk substrate for a j-device, and in particular to a texturing method for a magnetic disk substrate.

[Prior art] Magnetic disk drives are trending towards larger capacities and higher densities.
Magnetic media are shifting from conventional coated media to g-film media made by sputtering or plating.

As the density increases, the distance between the magnetic disk and the magnetic head, that is, the flying height, is becoming smaller and smaller, and recently it has become less than 0.3 pm.

Since the flying height of the head is extremely small, any protrusion on the disk surface may cause a head crash and damage the disk surface.

Furthermore, even minute protrusions that do not cause head crashes tend to cause various errors when reading and writing information.

On the other hand, magnetic disk drives are becoming smaller in size as well as increasing in capacity and density, and spindle rotation motors and the like are also becoming smaller and smaller. As a result, the torque of the motor is insufficient, which tends to cause the head to stick to the disk surface and not fly up.

A so-called "texturing method" has been adopted as a means to prevent this head from sticking by reducing the contact between the head and the substrate surface. This "texturing method" is a method of forming fine grooves on the surface of the base of a magnetic disk.

In general, the main texturing method used is to press a wrapping tape with an average abrasive grain size of 1 to 15 pm onto the surface of a rotating magnetic disk substrate using a pressure roller (hereinafter referred to as "tape wrapping"). .

[Problems to be Solved by the Invention] However, when texturing is applied by such a method, RmaxO・08~0・5g on the base surface.
There are protrusions on the order of m, and problems arise due to the protrusions.

Therefore, the present invention was created with the aim of solving such problems in the conventional tape wrapping process and obtaining a textured surface without protrusions.

[Means for Solving the Problems] The present invention provides a first step of pressing a roughening tape onto the substrate surface with a pressure roller while rotating a magnetic disk substrate, and an average roughening of the wrapping tape used in the first step. The present invention relates to a method for texturing a magnetic disk substrate, characterized by comprising a second step of polishing using abrasive grains smaller than the abrasive grain diameter.

Note that it is desirable that the average diameter of the abrasive grains used in the second step is smaller than 0.6 JLm, and that the abrasive grains are colloidal silica (silica sol).

[Effect] The present invention is divided into the following first step and second step.

The first step is normal tape wrapping.

The average abrasive grain diameter of the lapping tape used in this step is selected depending on the final required roughness of the magnetic disk, but generally a diameter of 1 to 15 Bm is adopted. Similarly, the lubricant used during tape wrapping is a general lubricant for grinding. Other base rotation speeds and polishing times are also possible under general conditions.

Also, there is no problem even if this first step is performed twice, for example, the first time is treated with a roughing tape with an average abrasive grain of 10 gm, and then the second time is treated with a 3p, m lapping tape. do not have.

The second step is a step of polishing using abrasive grains smaller than the average abrasive grain diameter of the lapping tape used in the first step.

That is, this step serves to remove the protrusions on the surface of the substrate that were generated in the first step.

Therefore, the average diameter of the abrasive grains used in this process is 0.
It is desirable that it be smaller than 54 m.

This is because when using abrasive grains with an average abrasive grain diameter of 0.61 Lm or more, the abrasive grains in the second process may cause protrusions or create fine grooves (which is the main purpose of texturing).
This is because even the material (formed in the first step) will be removed. From this, it can be said that the optimum average abrasive grain diameter is 0.3 m or less.

The present invention is different from the prior art in that this second step is added, and specific methods for the second step include the following methods.

■This method uses the same mounting and lubricant as in the first step. That is, in the tape lapping method, a roughing tape having an average abrasive grain diameter of less than 0.51 Lm is used for short-time processing.

■Using the same equipment as in the first step, using so-called cleaning tape such as tape-shaped cloth, polyurethane, artificial leather, polyester, polyamide, polyacrylonitrile tape instead of roughing tape,
This method uses a polishing liquid in which abrasive particles having an average abrasive particle diameter of less than 0.54 m are suspended in water or the like.

Naturally, a surfactant or the like may be added to this polishing liquid.

(2) This method uses a so-called polishing machine as a processing device, a donut-shaped cloth, polyurethane, artificial leather, etc. as a polisher, and a polishing liquid similar to (2).

Here, in methods (1) and (2), the pressure roller may be vibrated parallel to the disk base surface.

The schematic structure of a device suitable for realizing the above method is as follows.
From the figure it is shown in FIG.

Figure 1 shows a device suitable for Okaki's methods 1 and 2.
is a disk base, and 2 is a rubber roll.

3 is a tape, and in this device, the tape 3 is polished while being pressed against the rotating disk base 1 by a rubber roll 2.

FIGS. 2 and 3 show an apparatus suitable for the method (2) above.

In Figure 2, 4 is a disk base, 5 is a polisher,
Reference numeral 6 denotes a holding plate, and in this apparatus, a rotating disk 2Si plate 4 is sandwiched between polishers 5 held by the holding plate 6 for polishing.

In FIG. 3, 7 is a disk base, 8 is a carrier,
9 is a polisher, and 10 is a holding plate. In the same device, a carrier 8 equipped with a disk base 7 is sandwiched between the polishers 9 held by the holding plate 10.
and polishing while rotating the carrier 8.

The material of the abrasive grains used in the first and second steps of the present invention may be any material commonly used for polishing, such as alumina, silicon carbide, chromium oxide, and diamond. In method (2), colloidal silica (silica sol) may be added in addition to these.

Colloidal silica (silica sol) not only has excellent ability to remove protrusions, but also does not push abrasive grains in and has excellent cleaning properties.This makes it easy to clean after the second step. This is because very few abrasive grains remain on the surface of the substrate, such as those caused by indentation, which can cause defects in the magnetic disk.

[Example] After applying N1-P plating to a perforated disc with an outer diameter of 95 mm, an inner diameter of 25 mm, and a thickness of 1.27 mm, the surface was Rized.
maxo, mirror polished to 03ILm or less
Texturing processing was performed under the conditions shown in the table.

The results are shown in the column of surface condition in Table 1, and it can be seen that there are no protrusions on the surface of any of the examples of the present invention in which the second step was performed after the first step, whereas in the first step In the comparative example (conventional method), the value was 0.1-0.5.
1Lmc7) Many protrusions were present.

In addition, Fig. 4 shows a chart of the surface roughness of the substrate obtained under the conditions of Example 2 in Table 1, and Fig. 5 shows a chart of the surface roughness of the substrate obtained under the conditions of Comparative Example 2 in Table 1. In contrast to the uniform pattern shown in FIG. 5, it can be seen that there are many protrusions.

[Effects of the Invention] As described above, the present invention has the following advantages: After carrying out the first step (conventional method) of pressing the wrapping tape against the substrate surface with a pressure roller while rotating the magnetic disk substrate, the first step is further carried out. By performing the second step of polishing using abrasive grains smaller than the average abrasive grain diameter of the roughing tape used, the protrusions generated in the first step can be removed without removing the fine grooves on the surface of the magnetic disk substrate. made it possible to remove it.

This provides a method for forming a good substrate surface suitable for high-density magnetic disk substrates.

[Brief explanation of drawings]

1 to 3 are schematic structural diagrams of an apparatus applied to implement the method of the present invention, and FIGS. 4 and 5 are 2! It is a chart figure showing the surface roughness of the board surface.

Claims (3)

[Claims] (1) A first step of pressing the wrapping tape against the substrate surface with a pressure roller while rotating the magnetic disk substrate, and polishing using abrasive grains smaller than the average abrasive grain diameter of the wrapping tape used in the first step. A method for texturing a magnetic disk substrate, comprising a second step. (2) The method for texturing a magnetic disk substrate according to claim (1), wherein the abrasive grains used in the second step have an average diameter of less than 0.6 μm. (3) The method for texturing a magnetic disk substrate according to claim (1), wherein the abrasive grains used in the second step are colloidal silica (silica sol).