JPH11273063A - Texturing method of magnetic disk substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To process a substrate in high product yield while preventing production of comets (bites of abrasive grain into the substrate) by adjusting the position to drop an abrasive slurry to a polishing tape according to the water holding rate of the polishing tape. SOLUTION: An abrasive slurry is dropped between a polishing tape 2 and a first guide roller 7. A second guide roller 8 is disposed just under the first guide roll 7 so that the distance L between the center axes of both guide rollers 7, 8 is preferably <=20 mm and the stretching angle of the polishing tape between the guide rollers 7, 8 to the horizontal line is <=60. Thus, the polishing tape 2 is enough in contact with the guide roller 7. When the polishing tape 2 has a high water holding rate, the abrasive liquid nozzle 4 is disposed near a contact roller 3. When the polishing tape 2 has a low water holding rate, the abrasive liquid nozzle 4 is disposed far from the contact roller 3. Thus, the water absorption and the dispersion state of free abrasive grains on the polishing tape 2 are controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for texturing a magnetic disk substrate, and more particularly to a method for texturing a surface of a magnetic disk substrate by slurry grinding using a slurry of loose abrasive grains and a polishing tape. The present invention relates to a method for preventing free abrasive grains from digging into the surface of a magnetic disk substrate and dramatically improving product yield.

[0002]

2. Description of the Related Art Generally, a magnetic disk used as an external storage device of a computer or the like is formed by subjecting an aluminum alloy substrate to a non-magnetic plating treatment such as alumite treatment or Ni-P plating and then forming an underlayer such as Cr. Then, a magnetic layer of a Co-based alloy is formed, and a carbonaceous protective layer is further formed.

In recent years, the density of such a magnetic disk has been increased, and accordingly, the distance between the magnetic disk and the magnetic head, that is, the flying height has become smaller and smaller. 0.0μ ”or less. As described above, since the flying height of the magnetic head is extremely small, if there is a projection on the magnetic disk surface, a head crash may be caused and the disk surface may be damaged. Even small protrusions that cannot be reached tend to cause various errors in reading and writing information, and therefore, in the manufacture of magnetic disks, it is necessary to reduce surface defects due to the attachment of foreign matter (particles) such as dust to a substrate. Is important.

On the other hand, the size of magnetic disks has been reduced in parallel with the increase in capacity and density, and motors for rotating spindles and the like have become smaller. For this reason, a phenomenon in which the torque of the motor is insufficient and the magnetic head does not fly while being fixed to the magnetic disk surface is likely to occur. As means for preventing the sticking of the magnetic head by reducing the contact between the magnetic head and the surface of the magnetic disk, a process of forming a fine groove on the substrate surface of the magnetic disk and performing a surface process called texture processing is performed. Have been done.

Conventionally, as a method of texturing a substrate, for example, tape grinding using a fixed abrasive type polishing tape (Japanese Patent Laid-Open No. 1-86320) or a polishing slurry in which free abrasive grains are suspended is applied to a polishing tape. Slurry grinding performed by adhering to a surface (JP-A-3-147518) is known.

Referring to FIG. 6, a description will be given of a slurry grinding method among conventional texture processing methods.

FIG. 6A is a schematic plan view for explaining a conventional texture processing method by slurry grinding, and FIG. 6B is a side view of the same.

As shown in the figure, a total of four polishing tapes 2 are provided on each of the front and back surfaces of a disk-shaped substrate 1 which is supported so that the plate surface is in a vertical direction and is rotating in the direction of arrow A.
Is pressed by a contact roller 3 and a polishing slurry in which free abrasive grains are suspended is supplied from a polishing liquid nozzle 4 to the polishing surface side of the polishing tape 2 to perform slurry grinding.
The contact roller 3 is a roller holding cylinder (not shown)
The polishing tape 2 is pressed against the surface of the substrate 1 with a predetermined force. The polishing tape 2 is guided by the guide rollers 5 and 6 and travels in the direction of arrow B. The polishing tape 2 is polished with the surface of the substrate 1 always in contact with a new tape surface. Of these, it is dropped from above onto the guide surface of the polishing tape 2 by the inner guide roller 5. The polishing tape 2 reciprocates (oscillates) in the direction of arrow C by reciprocating the contact roller 3 so that the entire surface of the substrate 1 can be polished, and at the same time, stripes formed by polishing the substrate 1 with the polishing tape 2. (Cross angle) has a predetermined angle.

[0009]

The substrate surface treatment (reducing the substrate surface roughness or reducing the surface roughness to meet the required characteristics such as low flying characteristics and abrasion resistance) by tape grinding or slurry grinding.
In order to cope with the reduction of the flying height of the magnetic head due to the recent rapid increase in capacity, it is necessary to reduce the amount of abrasive grains generated during texture processing, which has not been regarded as a problem in the past. The bite (hereinafter referred to as “comet”) becomes a defect in the subsequent glide inspection, and the product yield has been reduced.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a method of performing texturing with a high product yield while preventing the occurrence of comet in texturing a magnetic disk substrate by slurry grinding. Aim.

[0011]

According to the present invention, there is provided a method for texturing a substrate for a magnetic disk, comprising: polishing the surface of the substrate for a magnetic disk with a polishing slurry in which free abrasive grains are suspended and a polishing tape. Wherein the position at which the polishing slurry is dropped onto the polishing tape is adjusted in accordance with the water retention of the polishing tape.

In other words, the present inventors have conducted intensive studies to solve the above-mentioned conventional problems, and as a result, the dispersibility of free abrasive grains on the polishing tape and the adhesion of the polishing tape to the guide roller have caused comet formation. They have found that they are important factors, and that these factors depend on the relationship between the water retention of the polishing tape and the dropping position of the polishing slurry, and have completed the present invention.

As described above, the flying height is 1.0 μ ″.
In the following high-capacity magnetic disks, under normal texture conditions, the abrasive grains bite into the substrate due to the excessive polishing by the abrasive grains and the influence of the residual abrasive grains, and cannot be removed, so that the flying height does not decrease.

On the other hand, a polishing tape used for slurry grinding has a different water retention ratio depending on the material, and therefore, the dispersion state of the polishing slurry also greatly differs.

FIG. 2 shows the water retention of the polishing tape and the polishing slurry dropping distance during texture processing (the length of the polishing tape between the point where the polishing tape comes into contact with the substrate and the point where the polishing slurry is dropped by pressing with the contact roller). Fig. 3
The relationship between the number of comet generation and the polishing slurry dripping distance
FIG. 4 shows the relationship between the grinding speed and the polishing slurry dropping distance, respectively. From these graphs, the following can be understood.

That is, from FIG. 4, it can be seen that the grinding speed increases as the polishing drop position increases, but if the grinding speed is too far, the number of comets increases as shown in FIG. This is presumed to be because if the dropping distance becomes too large, water absorption into the polishing tape proceeds too much, the surface of the polishing tape becomes only free abrasive grains, and the substrate and the polishing tape come into a dry contact state.

In addition, a polishing tape having a large water retention rate has a large amount of free abrasive grains and a large grinding speed, and may increase the number of comets.

Accordingly, as shown in FIG. 2, the polishing tape having a higher water retention rate has a smaller dropping distance of the polishing slurry.
The drip position is brought closer to the contact roller, shortening the water retention time, preventing dry contact, and reducing the number of comets.

Conversely, a polishing tape having a small water retention rate has a large dropping distance of the polishing slurry, that is, a position where the polishing slurry is dropped far from the contact roller to maintain a good water retention state and a good dispersion state, thereby generating a comet. To prevent

Further, from the study of the present inventors, the following has been found regarding the relationship between the polishing tape and the guide roller. That is, usually, the polishing slurry is dropped between the polishing tape and the guide roller, but when the polishing tape and the guide roller are not tightly adhered, the polishing slurry passes through these gaps or is applied to the polishing tape. In some cases, the dispersion and water retention of the polishing slurry become insufficient, and a normal polishing abrasive layer is not formed on the polishing tape surface.

However, as described in the second aspect, by ensuring the vertical spacing of the guide rollers and the tension angle of the polishing tape, a good contact surface is formed between the polishing tape and the guide rollers, and the polishing on the polishing tape is performed. Good dispersion of the slurry,
The water retention state is secured, and uniform texture processing becomes possible.

Further, as a result of the study by the present inventors, the following findings were obtained for the contact roller. That is, a contact roller is generally formed by winding a surface layer (hereinafter, referred to as a “rubber layer”) made of an elastic material such as rubber around the outer peripheral surface of a metal roller body, and has a role of pressing a polishing tape against a substrate. However, the balance of the pressing force is delicately related to the texture processing conditions. If the metal part (roller body) of this contact roller is too thick, the soft touch force of the rubber layer is canceled out, resulting in a hard touch.
If the rubber layer is too thick, the touch force becomes weak, and good texture processing cannot be performed in any case.

On the other hand, by adopting the conditions defined in claim 3, an optimal touch force can be obtained, and good texture processing can be performed.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for texturing a magnetic disk substrate according to the present invention will be described below.

As the magnetic disk substrate in the present invention, a substrate made of an aluminum alloy is generally used.
Usually, after processing the aluminum alloy substrate to a predetermined thickness, the surface thereof is mirror-finished, and then a nonmagnetic metal, for example, a Ni-P alloy or a Ni-Cu-P alloy is electroless-plated on the substrate surface. For example, a film having a thickness of about 5 to 20 μm to form a surface layer is used. In general, this substrate is polished on its surface layer and then textured to form specific irregularities and streak patterns.

The polishing is carried out, for example, by sandwiching a substrate between polishing pads having free abrasive grains attached to and impregnated on the surface thereof and supplying a polishing liquid such as an aqueous solution of a surfactant. In a normal case, the surface layer of the substrate is polished by about 2 to 5 μm by such polishing, and the surface thereof has an average roughness Ra of 50 ° or less, preferably 30 ° or less.
鏡 Mirror finish below.

In the method for texturing a magnetic disk substrate of the present invention, in such texturing of a magnetic disk substrate, slurry grinding using a slurry of loose abrasive grains and a polishing tape is performed. Preferably, the first-stage texture processing is performed by slurry grinding performed by attaching a slurry of loose abrasive grains to a polishing tape, and the second-stage texture processing is performed as a finishing process after the first-stage texture processing.

Hereinafter, such texture processing of the present invention will be described in detail with reference to the drawings.

FIG. 1A is a schematic plan view for explaining a texture processing method according to the present invention, and FIG. 1B is a side view of the same. 1, members having the same functions as the members shown in FIG. 6 are denoted by the same reference numerals.

In the first stage of texturing, as shown in FIG. 1, a total of four polishing tapes 2, two on each of the front and back surfaces of the disk-shaped substrate 1 rotating in the direction of arrow A, are contact rollers 3. And a polishing slurry in which free abrasive grains are suspended is supplied from the polishing liquid nozzle 4 to the polishing surface side of the polishing tape 2 to perform slurry grinding. The contact roller 3 presses the polishing tape 2 against the surface of the substrate 1 with a predetermined force by a roller pressing cylinder (not shown). The polishing tape 2 is guided by guide rollers 7 and 8 (first guide roller 7 and second guide roller 8) and
, And the substrate 1 is polished in such a manner that the surface of the substrate 1 always comes into contact with a new tape surface. The polishing slurry is supplied from the polishing liquid nozzle 4 to the first guide roller 7 and the polishing tape 2.
It is dripped at the meeting part with. The polishing tape 2 reciprocates (oscillates) in the direction of arrow C by reciprocating the contact roller 3 so that the entire surface of the substrate 1 can be polished, and at the same time, stripes formed by polishing the substrate 1 with the polishing tape 2. (Cross angle) has an angle of about 2 to 10 °.

In the present invention, in such a texturing process, a drop distance between a point at which the polishing tape 2 is pressed by the contact roller 3 and comes into contact with the substrate 1 and a point at which the polishing slurry is dropped on the polishing tape 2. Is adjusted according to the water retention rate of the polishing tape 2 used for texture processing.

That is, as described above, a polishing tape having a high water retention has a high absorption rate of water (aqueous lubricant solution) in the polishing slurry, so that a long time is required from dropping of the polishing slurry to grinding. The polishing slurry absorbs a large amount of water in the polishing slurry, and the surface of the polishing tape is insufficient in water, and the contact state between the substrate and the polishing tape becomes dry contact, so that comet easily occurs. Therefore, when a polishing tape having a high water retention rate is used, the drop distance of the polishing slurry is reduced. That is, the installation position of the polishing liquid nozzle 4 is brought closer to the contact roller 3.

On the other hand, a polishing tape having a low water retention rate has a low water absorption rate of water in the polishing slurry. Therefore, in order to uniformly and satisfactorily adjust the water absorption state of the polishing tape and the dispersion state of free abrasive grains, the polishing tape is required. It is preferable to make the contact time with the slurry relatively long. Therefore, when a polishing tape having a low water retention rate is used, the drop distance of the polishing slurry is increased. That is, the installation position of the polishing liquid nozzle 4 is kept away from the contact roller 3.

In general, the drop distance with respect to the water retention of the polishing tape depends on the concentration of the polishing slurry to be used and other texturing conditions, and it is difficult to show a specific numerical value. Preferably, the drop distance is determined.

When the water retention of the polishing tape is 100% or less: dropping distance 130 to 150 mm When the water retention of the polishing tape is 100 to 300%: dropping distance 80 to 120 mm When the water retention of the polishing tape is 400 to 600% : Dropping distance 130 to 150 mm As described above, the polishing slurry is dropped between the polishing tape 2 and the guide roller (first guide roller 7). If the roller 7 is not in close contact with the roller 7, the polishing slurry is not sufficiently dispersed into the polishing tape and water is not sufficiently absorbed, and a normal polishing abrasive layer is not formed on the surface of the polishing tape. It will be easier.

In order to prevent such a problem, in the present invention, as shown in FIG.
A second guide roller 8 is provided immediately below the guide roller 7 of the first embodiment, and the distance L between the center axis of the first guide roller 7 and the center axis of the second guide roller 8 is reduced to, for example, 20 mm or less. It is preferable that the tension angle θ of the polishing tape between the first guide roller 7 and the second guide roller 8 with respect to the horizontal (hereinafter, simply referred to as “tension angle”) is 60 ° or less. Here, the tension angle θ is an angle formed between the axis and the polishing tape 2 when a horizontal axis passing through an upper contact point where the guide roller 8 contacts the polishing tape 2 is taken.

In this way, the polishing tape 2 and the first guide roller 7 are firmly adhered to each other, and the dropped polishing slurry is uniformly absorbed and dispersed in the polishing tape, so that the polishing tape has a good surface. A sharp abrasive grain layer is formed, and the occurrence of comet is prevented.

The center axis of the first guide roller 7 and the second axis
The distance L from the center axis of the guide roller 8 and the tension angle θ of the polishing tape between the guide rollers 7 and 8 are too small in terms of the configuration of the apparatus. 13 to 20 mm, and the tension angle θ is preferably 50 to 60 °.

The contact roller 3 has a metal roller body 3A as shown in FIG.
And an elastic material layer such as a rubber layer 3B formed on the outer peripheral surface of the roller body 3A.
If the balance with the thickness of the polishing tape 2 is not kept well, the touch force of the polishing tape 2 on the substrate 1 becomes excessive or insufficient, and good texture processing cannot be performed.

[0040] In the present invention, referred to as preferably the outer diameter D ₁ and the ratio of the outer diameter D ₂ of the metal roller body 3A D ₁ / D ₂ (hereinafter "diameter ratio D ₁ / D _2" of the contact roller 3 .) To 1.75
By setting the range of ~ 1.85, the above-mentioned touch force is adjusted to the optimum range, and the comet is prevented, and the texture processing effect is enhanced.

The other conditions of the texturing according to the present invention will be described in more detail. The slurry grinding conditions for the first-stage texturing are as follows. 1.0 to 2% by weight, the supply amount of the polishing slurry is 9.0 to 21.0 ml / min, and the number of rotations of the substrate is usually 50 to 5000 times / min, preferably 800 to 1 / min.
The number of reciprocations (oscillation frequency) of the polishing tape in the radial direction of the polishing tape is 500 times / minute or more, preferably 100 to 5000 times / minute, and the pressing pressure of the cylinder is 1.
0 to 3.0 kg / cm ² , the polishing time is 5 to 30 seconds, and the tape feeding speed is in the range of 1 to 10 mm / sec.

In the present invention, by performing the first-stage texture processing, the average roughness Ra of the substrate surface is 3
At 0 ° or less, irregularities having a maximum protrusion height Rp of 300 ° or less are formed, and the formed lines cross at an angle (cross angle) of 0.5 to 40 °, preferably 1 to 10 °. It is desirable to form the surface shape of the pattern on the substrate surface. Here, the definition of the surface shape of the substrate is defined by JIS surface roughness (B0601).

The surface average roughness Ra and the maximum protrusion height Rp are determined by the above-mentioned slurry grinding conditions, particularly the abrasive grain size, the substrate rotation speed, the tape feed speed, the reciprocating number of the polishing tape (oscillation frequency), This can be achieved by appropriately adjusting the pressing pressure of the cylinder and the polishing time within the above ranges.

On the other hand, the angle at which the texture streaks intersect (cross angle) can be achieved by adjusting the number of rotations of the substrate and the number of reciprocating movements of the polishing tape (oscillation frequency) in the above range. .

As the first-stage textured polishing tape, for example, a non-woven fabric tape or a woven fabric tape made of nylon, acrylic, cellulose, polyester, rayon, or a combination thereof is used.

Examples of the free abrasive used together with the polishing tape include WA (white alumina), SiC
A (silicon carbide) -based or diamond-based abrasive can be used, and abrasive grains having an abrasive particle diameter of 0.01 to 10 μm are preferably used. Such loose abrasives are used as a polishing slurry suspended in a liquid (water or water-based liquid) with a dispersant.

The textured substrate surface may be further subjected to a second-stage texture finishing process, whereby the floating characteristics and the like can be further improved. The processing method of the second-stage texture finishing is not particularly limited, and may be WA-based, GC (green carbon).
-Type abrasive tape of fixed abrasive type, or WA-type, SiC
A polishing tape or the like using free abrasive grains such as a system or diamond is used.

The second-stage texture finishing process is performed without substantially changing the surface average roughness Ra or the cross angle formed in the first-stage texture processing process. Are selectively removed by polishing, and the maximum projection height Rp of the surface is 30 to 25.
0 °, preferably about 30-100 °.

In the case where free abrasive grains and a polishing tape are used in the second stage of the texture finishing treatment, non-woven tapes and woven tapes such as cellulose, nylon and rayon are preferably used as the polishing tape. For example, a WA-based or SiC-based abrasive having an abrasive particle size of 0.1 to 6 μm,
A diamond-based abrasive or the like is used, and is used in the form of a liquid slurry suspended in a water-based liquid together with a dispersant. As the second stage texture device, the same device as that shown in FIG. 1 is used. The slurry grinding conditions in the second-stage texture processing are not particularly limited, and usually, the abrasive grain concentration of the polishing slurry is 0.01 to 0.01.
5.0% by weight, supply amount of polishing slurry 9.0 to 21.0
ml / min, substrate rotation speed 50 to 300 rpm, polishing tape reciprocating frequency (oscillation frequency) 50 to 400 times /
Minute, cylinder pressing pressure 1.0-3.0 kg / cm ² ,
Polishing time 3-30 seconds, tape feed rate 0.5-5mm
Per second.

After performing such a texture processing, the magnetic disk is manufactured by washing and drying according to a conventional method to form an underlayer, a magnetic layer and a protective layer.

The underlayer is usually formed by sputtering Cr. The thickness of the Cr underlayer is usually 50 to
The range is 2000 mm.

As the magnetic layer, Co—Cr, Co—N
i, or Co-Cr-X, Co-Ni-X, Co-
A thin film layer of a Co-based alloy represented by WX or the like is preferable. Here, X is Li, Si, Ca, T
i, V, Cr, Ni, As, Y, Zr, Nb, Mo, R
u, Rh, Ag, Sb, Hf, Ta, W, Re, Os,
Ir, Pt, Au, La, Ce, Pr, Nd, Pm, S
m and one or more elements selected from the group consisting of Eu.

The magnetic layer made of such a Co-based alloy is
Usually, it is formed on the base layer of the substrate by means such as sputtering.
範 囲 range.

As the protective layer formed on the magnetic layer, a carbonaceous film is preferable. The carbonaceous protective layer is usually made of carbon under an atmosphere of a rare gas such as argon or He or in the presence of a small amount of hydrogen. A target is formed by sputtering as an amorphous carbon film or a hydrogenated carbon film. The thickness of the protective layer is usually 50 to 50.
0 ° range. Note that a lubricating film may be further formed on the protective layer in order to reduce the coefficient of friction.

[0055]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

In the following, the material and the water retention of the used polishing tape are as follows.

[0057]

[Table 1]

Example 1 After a Ni-P alloy plating layer was formed on the surface of an aluminum alloy substrate, a polished magnetic disk substrate (diameter: 95 mm) was textured by the apparatus shown in FIG. 1 according to the present invention. . The processing conditions of the first-stage texture processing and the second-stage texture processing are as follows. In FIG. 1, the distance L between the center axis of the first guide roller 7 and the center axis of the second guide roller 8 is 20 m.
m, and the tension angle θ of the polishing tape between the first and second guide rollers 7 and 8 was 60 °. As the contact roller, a roller having a diameter ratio D ₁ / D ₂ = 1.75 was used. The dropping distance of the polishing slurry is 10 to 200.
mm.

The first stage of texturing (four polishing tables)
Flop common) substrate rotational frequency: 1200 rpm Polishing Slurry: average particle diamond system size 0.10μm abrasive 0.08 wt% aqueous slurry polishing slurry supply amount: 576ml / min Polishing tape: abrasive tape No. II (woven tape) polishing tape feed speed: 2 mm / sec oscillation frequency of the abrasive tape: 1900 times / min cylinder pressing pressure: 2.0 kg / cm ² Polishing time: first according to the grinding speed 5 to 20 seconds Number of rotations of textured substrate in two stages : 1200 rpm Polishing slurry: water (does not contain abrasive grains) Polishing slurry supply: 576 ml / min. II Polishing tape feed speed: 2 mm / sec Oscillation frequency of polishing tape: 1900 times / min Cylinder pressing pressure: 2.0 kg / cm ² Polishing time: 5 to 20 seconds depending on grinding speed A streak pattern having a cross angle of 30 ° is formed by one-stage texture processing, and the surface roughness (Ra) of the substrate is set to 50 ° and the maximum projection height Rp is set to 250 °. Rp 200 ° without any change.

With respect to the substrate after the texture processing, the number of comets generated and the grinding speed with respect to the dropping distance of the polishing slurry were examined, and the results are shown in FIGS.

Example 2 In Example 1, a polishing tape No. 1 was used as a first-stage textured polishing tape using a urethane roll. I
In the same manner as above except that each of Nos. To III was used, the optimum position of the dropping distance of the polishing slurry was obtained, and the results are shown in FIG.

From FIG. 2, it is preferable that the higher the water retention of the polishing tape is, the more the polishing slurry dropping position is closer to the contact roller. Conversely, if the water retention of the polishing tape is low, the polishing slurry is dropped. It is understood that it is preferable to make the distance from the contact roller.

Examples 3 to 5, Comparative Examples 1 and 2 In Example 1, polishing tape No. 1 was used as the first-stage textured polishing tape. Using II, the dropping distance of the polishing slurry was set to 100 mm, which is optimal for this polishing tape.
The distance L between the center axis of the guide roller 7 and the center axis of the second guide roller 8 and the tension angle θ of the polishing tape between the first and second guide rollers 7 and 8 are variously changed as shown in Table 2. Texture processing was performed in the same manner except that the number of comet occurrences was examined for the substrate after the texture processing.
The results are shown in Table 2.

[0064]

[Table 2]

According to Table 2, the distance L between the guide rollers is 20 m.
m or less, and the polishing tape tension angle θ is preferably 60 ° or less.

Examples 6 to 8 and Comparative Examples 3 to 5 In Example 1, the polishing tape No. 1 was used as the first-stage textured polishing tape. Using II, the dropping distance of the polishing slurry was set to 100 mm, which is optimal for this polishing tape.
The texture processing was performed in the same manner except that a contact roller having a diameter ratio D ₁ / D ₂ was used, and the number of comets generated on the substrate after the texture processing was examined. The results are shown in Table 3.

[0067]

[Table 3]

According to Table 3, the diameter ratio D ₁ /
D ₂ it can be seen that 1.75 to 1.85 is preferable.

[0069]

As described in detail above, according to the method for texturing a magnetic disk substrate of the present invention, it is possible to prevent the occurrence of comet during texturing and to perform good texturing. For this reason, by performing texture processing according to the method of the present invention, the surface characteristics of the magnetic disk substrate are effectively improved, and the magnetic disk having excellent flying characteristics and abrasion resistance characteristics and excellent magnetic characteristics is obtained with a high product yield. It can be manufactured.

[Brief description of the drawings]

FIG. 1A is a schematic plan view illustrating an embodiment of a texture processing method by slurry grinding according to the present invention, and FIG. 1B is a side view of the same.

FIG. 2 is a graph showing a relationship between a water retention rate of a polishing tape and a polishing slurry dropping distance.

FIG. 3 is a graph showing the relationship between the number of comets generated and the polishing slurry dropping distance.

FIG. 4 is a graph showing a relationship between a grinding speed and a polishing slurry dropping distance.

FIG. 5 is a sectional view of a contact roller.

FIG. 6 (a) is a schematic plan view for explaining a conventional texture processing method by slurry grinding.
(B) is the same side view.

[Explanation of symbols]

 Reference Signs List 1 magnetic disk substrate 2 polishing tape 3 contact roller 3A roller body 3B rubber layer 4 polishing liquid nozzle 5, 6, 7, 8 guide roller

Claims (3)

[Claims] 1. A method for performing a texturing process by subjecting a surface of a magnetic disk substrate to a slurry polishing using a polishing slurry in which free abrasive grains are suspended and a polishing tape, wherein the water retention of the polishing tape is reduced. A method for texturing a substrate for a magnetic disk, comprising: adjusting a position at which the polishing slurry is dropped onto the polishing tape accordingly. 2. The method according to claim 1, wherein the polishing tape is guided by a first guide roller and a second guide roller provided immediately below the first guide roller. The polishing slurry is dropped on the upper side of the first guide roller, the distance between the center axis of the first guide roller and the second guide roller is set to 20 mm or less, and the distance between the first guide roller and the second guide roller is reduced. A method for texturing a substrate for a magnetic disk, wherein a tension angle between a polishing roller and a guide roller with respect to a horizontal direction is 60 ° or less. 3. The method according to claim 1, wherein a roller having a surface layer made of an elastic material formed on an outer peripheral surface of a metal roller body is used as the contact roller for pressing the polishing tape against the magnetic disk substrate. a method, for a magnetic disk ratio D ₁ / D ₂ between the outer diameter D ₂ of the outer diameter D ₁ and the metallic roller body of the contact roller, characterized in that a 1.75 to 1.85 Substrate texture processing method.