JP2000042889A - Polishing method for end surface of recording medium original plate, polishing member used for this method and recording medium original plate manufactured by this polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To polish the end surface as the mirror surface while holding an end surface shape of a recording medium original plate having a trapezoidal shape by polishing the end surface of the recording medium original plate by using polishing wheels having specific Shore hardness and specific density. SOLUTION: The end surface of a recording medium original plate, that is, a glass hard disk original plate is mirror finished by using polishing wheels 2, 2', 2" on which Shore hardness falls within a range of D15 to 80 and density falls within 0.5 g/cm3 to 1.5 g/cm3. Thus, a surface state of the end surface is put in an extremely excellent state by removing bits remaining after cutting by the polishing diamond wheels of the end surface of the recording medium original plate by about 70% or more, desirably, about 80%, more desirably, about 90%, further desirably, about 95% or more, an end surface shape is maintained as a trapezoidal shape, and the radius of curvature of both corner angles of a trapezoid forming the end surface can be held in about 50 μm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner / outer peripheral processing of a recording medium original plate, in particular, a finish polishing method for an end surface of a recording medium original plate, a polishing member used in the method, and a recording medium polished by the same method. For a master plate.

[0002]

2. Description of the Related Art The processing technology of aluminum CDs used as recording media for personal computers is not limited, and glass is used in place of aluminum as a material for hard disks for CDs and MDs for various acoustic media. As the quality of products has increased, high-quality products have been increasingly demanded, and the development of processing techniques corresponding to such needs has become increasingly important. Recording medium, for example, glass hard disk, raw material melting, molding, blanking process including a process such as pilot hole processing, and a substrate process including an inner and outer peripheral processing process that is the object of the end face polishing method according to the present invention, It is offered to the market as a final product disk through the media process completed as a hard disk, but in the initial process of processing, not only both sides of the original plate but also the end surface should be polished well. Accordingly, there is a demand for prevention of trouble in a post-process due to contamination caused by surface treatment that is not sufficiently performed and many pits are present on the surface.

Conventionally, the following method has been employed for polishing the outer peripheral portion of a recording medium master plate, for example, a glass hard disk master plate. That is, after processing the end surface of the glass hard disk original plate into a trapezoidal shape with a diamond wheel, a plurality of glass hard disk original plates having been subjected to the end surface processing step are uniformly aligned on the end surface and overlapped side by side, and after fixing this by fixing means, This is a method in which an end surface is polished with a brush having a specific thickness and rigidity while supplying an inorganic material, for example, cerium oxide as a polishing aid in a slurry state.

However, the biggest drawback of mirror finishing of the end face of a glass hard disk original plate with this brush is that
Since the discs are stacked directly on each other, it is difficult for the brush to hit the valley-shaped dent formed between the end faces of adjacent discs. The removal of the pits generated during the edge cutting due to the insufficiency resulted in insufficient removal of fine particles such as polishing aids into the remaining pits as foreign matter, and these particles fell off in the subsequent processing step This causes the glass hard disks 11 and 12 to be contaminated, and when a mechanical impact is applied to the pits, micro cracks are generated, which easily damages the pits, and causes defective products.

[0005] Furthermore, if the valley-shaped depression is to be sufficiently polished with a brush, both corners of the end face of the trapezoidal end face are scraped off by a brush, and both corners, for example, 1 in FIG.
Another problem is that a rounded shape having a curvature exceeding an allowable range is formed in three portions, and a desired end face shape cannot be obtained. Further, as a troublesome problem, even if irregularities such as pits generated by diamond polishing are removed, new scratches may be formed by the brush. By the way, the above is a problem due to processing restrictions, but another major problem is a problem of treating a large amount of water used for polishing including a polishing aid. In particular, since cerium oxide or the like, which is a soil contaminant, is used as a polishing aid, there is an environmental conservation problem that it is extremely costly to treat this cerium oxide without releasing it to the environment.

On the other hand, as a method of polishing the end face of a glass hard disk original plate, that is, a method of processing the inner and outer circumferences of the original plate, for example, a method using a polishing wheel described in Japanese Patent Application Laid-Open No. 64-5759 has been proposed. However, in this method, a polishing material is used together with an elastic member, and the structure of an apparatus to be used is complicated, so that at least the selection of the polishing material can uniquely set good polishing conditions. Not. For the grinding wheel, see
No. 294336, which discloses that the surface can have a smooth finish, but when used in metalworking or woodworking, a material that does not soften the wheel due to high temperature or high pressure. It proposes the use of an elastomer resin as a binder and does not teach that it can be used for mirror finishing of an end face of a glass disk or the like.

[0007]

SUMMARY OF THE INVENTION The present invention maintains the end face shape of a trapezoidal recording medium without using a polishing aid such as cerium oxide which requires high cost for environmental protection. Another object of the present invention is to provide a method capable of mirror-polishing an end face cut by a diamond wheel, a polishing member used in the method, and an original plate for a recording medium manufactured by the method.

[0008]

Means for Solving the Problems The present inventors have conducted various studies to solve the above-described problems, and as a result, have found that a polishing wheel having a specific shore hardness and a specific density is used. The present invention has been completed by finding that the above object can be easily achieved by mirror-polishing the surfaces of the inner and outer diameter portions of a recording medium master, for example, a glass hard disk master. In the present specification, a recording medium master is a manufacture of a recording medium capable of writing and reading electronic records such as a memory manufactured from a fragile inorganic material such as a glass hard disk master and a silicon wafer master. Material used for

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has a Shore hardness of D15.
Using a grinding wheel with a density in the range of 0.5 g / cm ³ to 1.5 g / cm ³ ,
The present invention relates to a method for mirror-polishing an end face of a recording medium original, that is, an original glass hard disk or the like. By adopting this method, pits remaining after cutting the end face of the recording medium original by a polished diamond wheel are reduced to 7 mm.
0% or more, preferably 80%, more preferably 90%,
More preferably, by removing 95% or more, the display state of the end face is made extremely good, and the end face shape is maintained as a trapezoidal shape, in other words, the corners of both corners of the trapezoid forming the end face are formed. This has the effect that the curvature R can be kept at 50 μm or less.

[0010] Thus, even if it is gripped by the robot hand, it is possible to prevent the occurrence of slippage and to prevent contamination by fine plastic powder caused by scratching the carrier for storing the hard disk.

Further, the second aspect of the present invention using the above-mentioned polishing wheel as a polishing member is achieved.

In the following, the first aspect of the present invention, the method for polishing the end face of the original plate for recording medium, will be described with reference to the original glass hard disk for convenience. The mirror polishing method of the end face portion according to the present invention can be applied to both an amorphous glass hard disk original plate and a crystalline glass hard disk original plate.

In the mirror polishing method according to the present invention, in the case of an original glass hard disk, regardless of whether it is crystalline or amorphous,
The present invention is applicable to a disk having a thickness of 0.4 to 1.4 mm, preferably 0.6 to 0.8 mm. Although the trapezoidal shape of the end face of the glass hard disk original plate has already been described, if this is schematically shown, it is as shown in FIG. The length t ₁ of the trapezoidal upper part a is usually about 300 μm, which is usually about 300 μm, and the inclination at both corners is 0.6 mm (600 μm) after cutting with a diamond. Is approximately 45 °. The size (diameter) of the pit is 2 on the end face after cutting by the diamond polishing wheel.
Objects of 0 to 50 μm are present over the entire surface.

Usually, pits after cutting by a diamond polishing wheel are often clogged with cutting chips and the like. It is preferable that the foreign substances contained in the pits are also removed by mirror polishing. The angles of the corners of the glass disk after cutting with a diamond polishing wheel are usually in the range of 45 ° ± 5 °.

The polishing wheel used in the method for mirror-polishing the end face of a glass disk according to the present invention may be one provided with a groove corresponding to the shape of the end face of the disk as shown in FIG. Alternatively, it may be formed into a cylindrical shape. In the latter case, it can also be used for processing the end face of the inner peripheral portion. As the properties required for the polishing wheel according to the present invention, those having a Shore hardness of D15 to 80 are preferably used. If the Shore hardness is less than D15, the life of the grinding wheel is short, and the need to frequently replace the grinding wheel arises. In order to keep the angle θ of both corners of the glass end face in a desired range, if the angle is less than D15, the strength becomes insufficient, which is not preferable. On the other hand, if the Shore hardness exceeds D80, the glass is too hard and may break the glass, which is not preferable.

The density of the polishing wheel is 0.5 g / cm ³
It should be in the range of to 1.5 g / cm ^3.
If the density is less than 0.5 g / cm ³ , the polishing wheel will have a short life, or abrasive grains will fall off so well that good mirror polishing cannot be performed. If the density exceeds 1.5 g / cm ³ , the glass may be broken, which is not preferable.

Although the abrasive grain size of the polishing wheel is not always an essential element, those having # 220 to # 1000 can be suitably used. If the abrasive grain size is coarser than # 220, the finish of the end face may be too rough to reach the desired level, and if it exceeds # 1000, it takes a relatively long time to remove the pits. The characteristic that the processing time is short in a short time may not be fully utilized. Needless to say, when a mirror finish is required, a finer particle size is preferable. In addition, as the abrasive grains, any one which can be generally used as a polishing material, such as SiC and Al ₂ O ₃ CeO ₂ , can be applied, but in this case, it can be said that SiC is preferable in view of the object to be polished. .

In the method of polishing the inner and outer peripheral end faces of the original glass hard disk by the polishing wheel according to the present invention, a polishing wheel that satisfies the requirements of Shore hardness and density among the above properties may be used. Of course, the grain size of the abrasive grains is # 220- #
Needless to say, 1000 can be more suitably used.

The conditions of the polishing method according to the present invention are as follows. In the polishing method according to the present invention, not only does not require a polishing aid during polishing, but it is not necessary to supply the slurry in the form of a slurry, so that scattering of glass powder generated during polishing is prevented. It may be done while supplying a small amount of water just to do so. In other words, it is a semi-dry polishing method. Therefore, there is no problem of processing the polishing aid required for environmental protection.

When a polishing wheel having the shape shown in FIG. 2 is used, the peripheral speed of the polishing wheel is 300 to 700 m /
Minutes. The load applied to the grinding wheel is 0.2-2
kg. The polishing time is determined depending on the level of the remaining amount of the pits, although there is a slight variation depending on the grain size of the grinding wheel used.
Seconds, preferably 20-30 seconds.

When the polishing wheel used in the polishing method according to the present invention has a cylindrical shape, the three outer surfaces a, b and c of the outer peripheral end face 10 shown in FIG. At the same time, or for polishing the inner circumference,
It is preferable to use an apparatus which can polish both surfaces corresponding to c and c surfaces. As such an apparatus, Shonan Engineering Co., Ltd. (16-11 Shibashinmachi, Kawaguchi City, Saitama Prefecture)
Hard disk end polisher. When the outer peripheral end face is polished by using this polishing machine, it is driven by a first drive system 5 for polishing an a-plane which is an upper part of a trapezoid forming an end face as schematically shown in FIG. Shaft 4
Is located above the glass hard disk original plate to be polished, which is fixed substantially vertically using a suction disk, and a shaft 4 ′ driven by a second driving system 5 ′ for polishing the surface of the corner b. Is located at an angle of about 90 ° with respect to the shaft 4 driven by the first drive system 5 for polishing the a-plane, and is arranged in accordance with the corner angle, and the C-plane is polished. The shaft 4 "driven by the third drive system 5" is disposed on the same horizontal plane as the position of the shaft 4 'driven by the second drive system 5' for polishing the surface of b,
In addition, it is only necessary to position the shaft 4 driven by the first drive system 5 for polishing the a-plane at an angle of about 90 ° and simultaneously grind the same load at the same peripheral speed with the same load. FIG. 4 shows the relationship between the polishing surface of the original glass hard disk and each polishing wheel on the same plane. The polishing of the end surface of the inner peripheral portion may be performed by operating a polishing wheel used for polishing the b surface and the c surface of the outer peripheral portion.

The peripheral speed of the grinding wheel fixed to each shaft is usually 300 to 700 m / min, and the load is 0.5 to 2.
0 kg, polishing time is 10-60 seconds, preferably 20
３０30 seconds. When this apparatus is used, polishing conditions other than those described above may be in accordance with standard operating conditions of the apparatus.

[0023]

EXAMPLES Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

Both the measurement of the pit removal rate and the measurement of the corner curve of the corner of the end face were performed by visual observation using an electron microscope photograph.

As the polishing wheels used in Examples 1 and 2 described below, those commercially available as DLO abrasive series manufactured by 3M were used.

Example 1 An end surface of a glass disk original plate was polished using a polishing wheel having the shape shown in FIG. The state of the end face after polishing was a pit removal rate of 80%, the size of the pits remaining without being removed was 5 μm or less, and the curvature of the end face corner was 35 μm.

(Example 2, Comparative Example) Shonan Engineering Co., Ltd. is a polishing apparatus that can simultaneously mirror-polish three surfaces a, b, and c of the end surface 10 of a glass disk original plate schematically shown in FIG. Then, the hard disk end face polishing machine was set according to the standard operating conditions, and the Shore D hardness shown in Table 1 was 10 to 90 and the density was 0.3 g / cm ³ to
Polishing was performed at a peripheral speed of 500 mm / sec and a polishing time of 10 to 60 seconds using a material of 1.7 g / cm ³ .
The results are as shown in Table 1.

[0028]

[Table 1]

In a comparative example in which the Shore hardness and the density are out of the range usable in the present invention, when the Shore hardness is 10 and the density is 0.3 g / cm ³ , the pit removal rate is 50%, When R was 50 μm, Shore hardness was 90, and density was 1.7 g / cm ³ , the glass was broken shortly after the start of polishing, and mirror polishing could not be performed.

(Reference Example) Polishing with a brush is performed by stacking a plurality of glass hard disk original plates, fixing them on a rotating shaft, using cerium oxide as a polishing aid, and using pure water with 10 to 20%. Polishing was performed at 1000 m / min while supplying the slurry at a rate of 10 liter / min. Two types of polishing time, 60 seconds and 3,600 seconds, were employed. After the polishing was completed, a curve of a pit removal rate and a corner of an end face was measured. Table 2 shows the results.

[0031]

[Table 2]

In 60 seconds, the pit removal rate is as low as 5%,
At 3,600 seconds, the pit removal rate became 95%, but the curvature of the corner of the end face was as large as 100 μm, and there was a problem in practicality. Further, the occurrence of brush scratches was also observed on the mirror surface on the end face. On the other hand, according to the method of the present invention, as is apparent from Table 1, the amount of pits remaining after cutting the diamond polishing wheel is 70% or more, preferably 80% or more, more preferably 90% or more, and further preferably. 95% or more could be removed, and the size of the pits remaining without being removed was 5 μm or less, and the curvature of the end face could be maintained at about 20 μm. The method for polishing an end face of a recording medium master according to the present invention can be used for polishing the end face of a silicon wafer master as well as a glass hard disk master.

[0033]

As described above, according to the polishing method according to the present invention, the polishing time is 30 seconds, the pit removal rate on the end face of the recording medium original such as the glass hard disk original is 95%, and the end face is removed. Extremely excellent mirror polishing of the end face is achieved, with the curvature at both corners being about 20 μm, which is much lower than 50 μm or less, which is a standard for producing a glass hard disk original plate or the like. Further, in the recording medium master according to the present invention, since the number of pits remaining without being removed and the diameter thereof are both small, foreign matter remaining in the pits can contaminate the medium body in a later step. And the yield as a final product after the end of the media process is extremely good.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a shape of an end face of a glass hard disk.

FIG. 2 is a schematic view showing a shape of one embodiment of a grinding wheel according to the present invention.

FIG. 3 is a schematic diagram showing relative positions of respective polishing wheels relative to a position of a glass hard disk to be polished when three end surfaces of the glass hard disk are simultaneously polished by three independent polishing wheels. is there.

FIG. 4 is a schematic plan view illustrating a relationship between each polishing wheel and an end surface to be polished.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass disk, 2 ... Polishing wheel, 2 '... Polishing wheel, 2 "... Polishing wheel, 3 ... Suction plate, 4 ... Shaft, 4' ... Shaft, 4" ... Shaft, 5 ... First drive system, 5 ' ... Second drive system, 5 ″ third drive system, 10: outer peripheral end face, 11: board face, 12: board face, 13: both corners of the end face of the end face, a: one of three faces of outer peripheral end face 10 B, one of three surfaces of the outer peripheral end surface 10; c: one of three surfaces of the outer peripheral end surface 10.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsuhiko Uchida 16-11 Shibashinmachi, Kawaguchi City, Saitama Prefecture Shonan Engineering Co., Ltd. F term (reference) 3C049 AA03 AA09 AA18 CA01 CB01 CB05

Claims (6)

[Claims] 1. A method for polishing an end face of a recording medium original plate using a polishing wheel. 2. An end surface of a recording medium master plate is polished using a polishing wheel having a Shore hardness in a range of D15 to 80 and a density in a range of 0.5 g / cm ³ to 1.5 g / cm ^3. Method. 3. The method according to claim 1, wherein the three surfaces of the end surface of the recording medium master plate are simultaneously polished. 4. The polishing method according to claim 1, wherein a shaft on which three polishing wheels arranged so as to simultaneously polish three end faces of the recording medium master plate are simultaneously driven is polished. Method. 5. A polishing member used in the method according to claim 1. 6. An original plate for a recording medium, the end surface of which has been polished by the method according to claim 1. Description: