JP2006095679A - Polishing tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing tool, polishing a substrate to be processed while effectively restraining chipping, breakage and cracks in the substrate. <P>SOLUTION: This polishing tool is formed by fixing a plate-like grinding stone on the sector areas of the substrate surface having two or more sector areas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polishing tool that enables suitable rough cutting (lapping). Since the polishing tool of the present invention can provide a precise surface in which the occurrence of defects is suppressed, rough cutting when forming a magnetic recording medium that can be widely used as a recording medium in various electronic devices (computers, etc.) In the process, it can be particularly preferably used.

  Although the polishing tool of the present invention can be widely used in various applications, for the convenience of description, the background art related to polishing of a glass substrate for a magnetic recording medium will be mainly described here.

  Conventionally, aluminum substrates have been widely used as substrates for magnetic recording media including magnetic disks (for example, hard disks). On the other hand, in recent years, with the widespread use of various electrical appliances including small personal computers, portable audio / video recording / playback devices, etc. With respect to magnetic recording media, which are one of the important parts of the product, demands in various usage environments are increasing more and more.

  In order to meet such severe demands, glass substrates having high impact resistance, rigidity / hardness, and high chemical durability have been widely used in recent years. When this glass substrate is used for a magnetic recording medium in the form of a hard disk (HD), the flatness suitable for lowering the head on the magnetic recording surface, which is extremely important for increasing the density of the magnetic recording surface. There is also a general advantage that can be easily obtained.

  More specifically, in the field of magnetic disk substrates, mechanical properties such as thinness accompanying weight reduction and high rigidity capable of withstanding disk undulation during high-speed rotation are required, and higher recording density is required. The demand is very high. In order to achieve high recording density, the flying height of the magnetic head with respect to the magnetic disk substrate is becoming extremely small. To achieve this, the magnetic disk substrate has a flat surface such as a mirror surface and a small surface roughness. It is required that the surface is free from defects such as micro scratches and micro pits.

Therefore, it is necessary to polish the surface of the glass substrate with high accuracy. In the lapping process of a glass substrate, generally, processing with free abrasive grains (ZrO ₂ (FO), Al ₂ O ₃ (WA), SiC (GC), etc.) and processing with diamond pellets (Patent Document 1) )It has been known. Among these, the free abrasive processing tends to require a long time to process to a predetermined thickness with a low processing rate. On the other hand, the processing method using diamond pellets can achieve high-rate and short-time processing, but when the pellets are stuck on the surface plate, irregularities are produced. Tends to cause chipping, chipping and cracking.

Japanese Patent Laid-Open No. 11-90813

  An object of the present invention is to provide a polishing tool capable of eliminating the above-described drawbacks of the prior art.

  Another object of the present invention is to provide a polishing tool that can easily process a small-diameter and / or ultra-thin substrate.

  Still another object of the present invention is to provide a polishing tool that can easily process a small-diameter and / or ultra-thin substrate.

  As a result of diligent research, the present inventor is able to fix a plate-shaped grindstone in which abrasive grains are dispersed on a substrate to make a polishing tool, unlike conventional free abrasive grains in which loose abrasive grains are dispersed. The present inventors have found that it is extremely effective for achieving the above object.

The polishing tool of the present invention is based on the above knowledge, and more specifically includes at least a base material having two or more sector regions, and a plate-like grindstone fixed on the sector regions. Is.
For example, the present invention includes the following aspects.
(1) a substrate having two or more sector regions;
A polishing tool comprising at least a plate-like grindstone fixed on the sector region.
(2) The polishing tool according to item 1 above, wherein the plate-shaped grindstone is composed of a plate-shaped material and abrasive grains dispersed in the material.
(3) The polishing tool according to item 2 above, wherein the abrasive grains have a particle size of # 325 to # 2000.
(4) The polishing tool according to item 2 or 3, wherein the abrasive grains are diamond abrasive grains.
(5) A method for producing a glass substrate for a magnetic recording medium, comprising a step of polishing with the polishing tool according to any one of items 1 to 4.
(6) A method for producing a magnetic recording medium, comprising a step of polishing with the polishing tool according to any one of items 1 to 4.

When the polishing tool of the present invention having the above-described configuration is used, it is possible to effectively suppress the generation of convex / concave portions on the processed substrate surface based on the presence of loose abrasive grains (for example, based on the loose abrasive grains falling off). As a result, chipping, chipping and cracking of the substrate can be suppressed.
On the other hand, when a conventional diamond pellet is used, as shown in FIG. 2, there is a risk of hitting the pellet in the case of a small-diameter / thin board. In the case of a collision, there is a drawback that scratches, chipping, chipping, etc. occur.

  In addition, in the present invention, the surface of the substrate is divided into sectors, and a flat grindstone is arranged in each sector, so that the coolant flow between these sectors is also good during grinding. There is also an advantage.

  As described above, according to the present invention, grinding can be performed while effectively suppressing chipping, chipping, and cracking of the substrate to be processed.

  In addition, according to the present invention, a small diameter (for example, a disk having an outer diameter of up to about 21.6 mmφ) and / or an ultrathin (for example, a thickness), which has been impossible with conventional processing using loose abrasive grains. Wrapping of the substrate (disk up to about 0.381 mm) is also facilitated.

  In addition, according to the present invention, by changing the grain size of the abrasive grains dispersed in the plate-like grindstone, it is possible to cover a wide range from roughing to fine machining.

  Hereinafter, the present invention will be described more specifically with reference to the drawings as necessary. In the following description, “parts” and “%” representing the quantity ratio are based on mass unless otherwise specified.

(Polishing tool)
The polishing tool of the present invention includes at least a base material having two or more sector regions and a plate-like grindstone fixed on the sector regions.

(Basic aspect)
A basic aspect of the polishing tool of the present invention is shown in the schematic perspective view of FIG. 1 (a) and the schematic plan view of FIG. 1 (b). In this embodiment, a plate-shaped grindstone 2 corresponding to a sector is fixedly disposed on a base material 1 having a plurality of sectors (not shown) made of iron, casting, or the like. The plate-shaped grindstone 2 is fixed on the base material 1 by an adhesive, brazing, or the like, for example, as in the case of bonding a semiconductor element. In the embodiment of FIG. 1, the surface of the substrate 1 is divided into four sectors.

(Base material)
In the present invention, the substrate 1 is not particularly limited as long as a plurality of plate-like grindstones 2 can be fixed on the surface thereof. From the viewpoints of strength, workability, etc., the substrate 1 is preferably made of metal (including an alloy). Examples of such metals include iron, castings, stainless steel, and the like.

(Sector)
In the present invention, the surface of the substrate 1 is divided into two or more sector regions. The number of sectors is not particularly limited as long as a plurality of plate-shaped grindstones 2 can be fixed on the surface thereof. The shapes and / or sizes of the plurality of sectors may all be the same, and may be divided into groups of several shapes as necessary.

  In the present invention, the method for forming the sector is not particularly limited. For example, the sector is preferably formed by a method such as a metal bond or a resin bond.

(Plate-shaped grinding wheel)
A plate-like grindstone is obtained by dispersing abrasive grains in a plate material. The method for forming the plate-like grindstone is not particularly limited. For example, the plate-like grindstone can be formed by a method such as adhesion or fixing with a bolt.

(Surface smoothness of plate-shaped grindstone)
In the present invention, the “plate-shaped grindstone” refers to one having a smooth surface.
(Suitable abrasive)
In the present invention, for example, the following abrasive grains can be preferably used.
ZrO ₂ (FO), Al ₂ O ₃ (WA), SiC (GC), diamond.

  In the present invention, depending on the properties of the material to be polished, it can be used by appropriately selecting from the above-mentioned abrasive grains. When a series of materials called “glass ceramics” (for example, glass ceramics manufactured by OHARA, trade name: TS-10X) is used as a glass material for a hard disk, the glass ceramics are very hard. Since it is a material, it is very preferable to use diamond as the abrasive.

(Fixing method)
In the present invention, the method for fixing the grindstone 2 on the substrate 1 is not particularly limited. For example, it is preferable to use an adhesion technique (for example, brazing) used in the field of semiconductor elements.

(Grinding method)
The grinding method using the grinding tool of the present invention is not particularly limited. However, for example, a polishing method as shown in FIG. 4 is suitable from the viewpoint of sufficiently exhibiting the characteristics of the tool.

(Other aspects)
Another embodiment of a polishing tool that can be used in the present invention is schematically shown in FIG.

(Glass material)
Glass substrates for magnetic disks are attracting attention as substrates that take advantage of advantages such as high rigidity and low profile, and high impact resistance. The glass materials for these substrates are chemically tempered glass and crystallized glass. It is divided roughly. All of these materials are subjected to a tempering treatment in order to overcome the disadvantage of glass that is inherently brittle.

Usually, since the presence of scratches on the glass surface greatly impairs the mechanical strength, chemical strengthening treatment by ion exchange is performed from the viewpoint of improving disk reliability. In other words, a glass substrate (original plate) is immersed in an alkali molten salt, and by replacing alkali ions on the glass surface with larger ions in the molten salt, a compressive stress-strained layer is formed on the surface layer of the glass. The strength is greatly increased. Examples of the HD glass substrate preferably used include an aluminosilicate glass substrate containing Li ⁺ and Na ⁺ , a soda lime glass substrate containing K ⁺ and Na ^+, and crystallized glass.

(Suitable glass material)
The glass material that can be suitably used in the present invention is not particularly limited.
The glass material that can be used particularly preferably in the present invention is, for example, a series of materials called “glass ceramics”, and commercially available glass ceramics (trade name: TS-10X) manufactured by OHARA, for example. Can be mentioned.

(Precision polishing)
In processing a glass substrate for a magnetic recording medium, the lapped substrate is further subjected to precision polishing. Although such a precise polishing method is not particularly limited, for example, a polishing method disclosed in Japanese Patent Application Laid-Open No. 2004-162062 can be suitably used.

  Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1
A polishing tool was produced by the following method.
A polishing tool was produced by bonding a casting by brazing.

Example 2
A glass substrate for a magnetic recording medium was polished by the following method using the polishing tool obtained in Example 1.

The material of the disk was OHARA TS-10SX (thickness t = 1.0 mm). The final processed product was t = 0.635 mm. That is, lapping (rough cutting) × 2 steps, roughly 0.3 mm was roughly cut, and fine polishing using CeO ₂ × 2 steps, and finally t = 0.635 mm.

It is the model perspective view (a) and the model top view (b) which show the fundamental one aspect | mode of the polishing tool of this invention. It is an expansion model perspective view (a) and a model perspective view (b) which show the conventional diamond pellet. It is a model perspective view which shows the other aspect of the tool of this invention. It is a graph which shows an example of the grinding method using the tool of this invention.

Claims (6)

A substrate having two or more sector regions;
A polishing tool comprising at least a plate-like grindstone fixed on the sector region.   The polishing tool according to claim 1, wherein the plate-shaped grindstone includes a plate-shaped material and abrasive grains dispersed in the material.   The polishing tool according to claim 2, wherein a particle size of the abrasive grains is # 325 to # 2000.   The polishing tool according to claim 2 or 3, wherein the abrasive grains are diamond abrasive grains.   The manufacturing method of the glass substrate for magnetic recording media including the process grind | polished with the grinding | polishing tool of any one of Claims 1-4.   A method for manufacturing a magnetic recording medium, comprising a step of polishing with the polishing tool according to claim 1.

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