JP2007118173A - Polishing brush, brush adjusting fixture, and polishing brush adjusting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing brush, a brush adjusting method and a polishing brush adjusting method capable of surely polishing to the depth of a groove formed by adjacent chamfer parts by reducing the amount of polishing in an end surface and increasing the amount of polishing in the chamfer parts, and capable of adjusting angle of the chamfer part within a standard. <P>SOLUTION: The adjusting brush 4 for polishing end surfaces of a plurality of laminated glass boards 1 respectively formed with chamfer parts 12 and a side wall part 11 in the end surface 10 thereof. Outline of the brush is formed into a nearly cylindrical shape, and the peripheral surface thereof is formed into a polishing surface, and fibers 40 structuring the brush are formed so that diameter thereof is formed smaller as it comes closer to tips of the hair. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polishing brush for polishing an end surface of a glass substrate for a magnetic disk, a brush adjusting jig, and a method for adjusting a polishing brush.

  In recent years, with the advancement of information technology, information recording technology, particularly magnetic recording technology, has made remarkable progress. An aluminum substrate has been widely used as a substrate for a magnetic recording medium such as an HDD (Hard Disk Drive) which is one of the magnetic recording media. However, with the miniaturization, thinning, and high-density recording of magnetic disks, glass substrates that are superior in substrate surface flatness and substrate strength compared to aluminum substrates are gradually being replaced.

  As the magnetic recording technology has been increased in density, the magnetic head has been changed from a thin film head to a magnetoresistive head (MR head) and a large magnetoresistive head (GMR head). The flying height from the center is narrowed to about 10 nm. A magnetic head equipped with such a magnetoresistive element may cause a thermal asperity failure as an inherent failure. Thermal asperity failure means that the magnetoresistive element is heated by adiabatic compression or contact of air when the magnetic head passes while flying over a minute convex or concave shape on the magnetic disk surface. This is a failure that causes a read error. Therefore, for a magnetic head equipped with a magnetoresistive element, the surface of the magnetic disk is required to have extremely high smoothness and flatness. Further, if the magnetic layer is formed with dust or foreign matter attached, a convex portion is formed. Therefore, the glass substrate is required to prevent dust generation by removing irregularities and to perform advanced cleaning to remove foreign matter.

  Furthermore, in recent years, there is a tendency for the size of a substrate to be reduced in order to mount a large-capacity magnetic recording medium in a portable device. For this reason, 1.8-inch substrates, 1-inch substrates, or even smaller substrates have been demanded from conventional 3.5-inch substrates and 2.5-inch substrates. The smaller the substrate, the smaller the allowable dimensional error, and there is a need for more precise outer shape processing.

Under the circumstances as described above, the importance of the smoothness of the end face of the substrate has been recognized conventionally. In Patent Document 1 (Japanese Patent Laid-Open No. 10-154321), if the surface properties of the chamfered portion and the side wall portion formed on the end surface of the substrate are rough, particles are generated and adsorbed, and the particles adhere to the main surface of the substrate. It has been explained that this causes the formation of convex portions (paragraph 0010). And in patent document 1, it is supposed that the said problem can be solved by grind | polished an end surface smoothly until it reaches a mirror surface.
JP-A-10-154321

  FIG. 8 is a diagram for explaining a substrate end surface polishing apparatus. The glass substrate 1 is chamfered in a forming process prior to this, and the side wall portion 11 and the chamfered portion 12 are already formed on the end surface 10.

  As shown in the figure, a plurality of glass substrates 1 are stacked and held in a cylindrical shape. The polishing brush 2 is made of nylon fibers, has an outer shape that is substantially cylindrical, and has an outer peripheral surface that is a polishing surface. The rotation axes of the glass substrate 1 and the polishing brush 2 are substantially parallel, and are moved in opposite directions at the contact points by rotating in the same direction (CCW: counterclockwise in the figure). A nozzle 3 is in close proximity to the contact point between the glass substrate 1 and the polishing brush 2, and slurry (abrasive) is supplied.

  Here, as shown in FIG. 9A, polishing may not reach the depth 12a of the groove formed by the adjacent chamfered portions 12, and mirror polishing may be insufficient. This is considered because the fibers 20 of the polishing brush 2 are difficult to reach the back of the groove. If the mirror polishing is insufficient, the effect of preventing the generation and adsorption of dust and particles is reduced, which may cause the generation of thermal asperity. Therefore, if the chamfered portion 12 is to be sufficiently polished, it is necessary to increase the pressure applied by the polishing brush 2 to the glass substrate 1 or to polish it for a long time. However, in this case, the processing rate (polishing amount) is unstable, and the quality may vary.

  Further, the chamfered portion angle α of the glass substrate is finally required to be within a range of 40 ° <α <50 °. Conventionally, when the average of the chamfer angle after the end face polishing of a 1-inch substrate is measured, it is 48 to 49 °, and a part of the chamfered portion is 50 ° or more and is out of specification. If this standard is not met, it will be a defective product, and if there are many defective products, the yield will be reduced and the production cost may increase.

  Here, the diamond grindstone for end face grinding used in the forming step is adjusted so that the angle of the chamfered portion is 45 °. Since the diamond grindstone is hard, there is no risk of deformation, and the chamfered portion should be 45 ° on average when the forming process is completed. On the other hand, the polishing brush 2 used in the end surface polishing step cannot control the angle of the chamfered portion unlike the diamond grindstone because the nylon fiber is flexible.

  As shown in FIG. 9B, the reason why the chamfered portion angle α is increased is that, as a result of sufficient polishing for mirror polishing the chamfered portion 12 to the back, the side wall portion 11 is largely polished. It is thought that it will end. That is, if the polishing is conservative, the mirror finish of the chamfered portion 12 becomes insufficient, and if the polishing is sufficiently performed, the chamfered portion angle α becomes out of specification. In either case, the product was ineligible and the yield was a problem.

  In view of this, the present invention reduces the polishing amount of the end face and increases the polishing amount of the chamfered portion, thereby surely mirror-polishing to the depth of the groove formed by the adjacent chamfered portion and keeping the chamfered portion angle within the standard. It is an object of the present invention to provide a polishing brush that can be accommodated in a brush and a method for adjusting a brush adjusting jig and a polishing brush.

  In order to solve the above problems, a representative configuration of a polishing brush according to the present invention is a polishing for laminating a plurality of glass substrates each having a chamfered portion and a side wall portion formed on an end surface, and polishing the end surface. The brush has a substantially cylindrical shape, an outer peripheral surface is a polished surface, and the fibers forming the brush are formed in a shape whose diameter decreases toward the hair tip. . Thereby, the bristle tip of the polishing brush easily enters the groove formed by the adjacent chamfered portions, and mirror polishing can be reliably performed to the depth. Further, since the side wall portion of the substrate end face is not polished more than necessary, the angle of the chamfered portion can be kept within the standard.

It is preferable that the average of the cross-sectional area of the cross-section which forms the substantially triangular part of which the diameter is reduced toward the fiber tip is 0.156 mm ^{2 to} 0.311 mm ² . In other words, it is preferable that the ratio of the base and height of the substantially triangular portion of the cross section of the portion where the diameter decreases toward the fiber tip is sharp at an angle such that 7.780 to 15.555. Moreover, it is preferable that a fiber consists of nylon and a diameter is about 0.2 mm. In such a case, an effect can be obtained particularly.

  The glass substrate for magnetic disk may be made of aluminosilicate glass. In such a case, a good glass substrate for a magnetic disk can be obtained.

  The polishing brush may be used to polish a glass substrate for a magnetic disk mounted on a 1-inch hard disk drive or a hard disk drive using a magnetic disk having a smaller diameter than the 1-inch hard disk drive. The present invention is particularly effective because the chamfered portion becomes deeper as the substrate becomes smaller.

  Further, a representative configuration of the brush adjusting jig according to the present invention is a jig for adjusting the tip of the polishing brush, and the jig has a substantially cylindrical shape and has a circumferential surface on the outer peripheral surface. A number of grooves in the direction are arranged, and the tip of the fiber of the polishing brush is worn by rotating relatively with the polishing brush parallel to the axis, and the fiber diameter is reduced. It is made to make it small toward. By configuring as described above, the polishing brush can be adjusted quickly and efficiently.

  The groove preferably has a substantially V-shaped cross section, a pitch of 2 mm, a depth of 1.73 mm, and an opening angle of about 60 °. Thereby, it can adjust to a desired hair end. Further, by using aluminum as a main material, durability can be achieved.

  The adjustment may be performed by attaching a brush adjusting jig to the glass substrate polishing apparatus instead of the laminated glass substrate and adjusting the polishing brush. Thus, adjustment can be performed without using a dedicated device.

  A typical configuration of the method for manufacturing a magnetic disk glass substrate according to the present invention is to laminate a plurality of glass substrates each having a chamfered portion and a side wall portion formed on the end surface, and the end surface has a smaller diameter toward the hair end. It polishes using the brush for polishing which consists of a fiber which consists of. Thereby, the bristle tip of the polishing brush easily enters the groove formed by the adjacent chamfered portions, and mirror polishing can be reliably performed to the depth. Further, since the side wall portion of the substrate end face is not polished more than necessary, the angle of the chamfered portion can be kept within the standard.

  The glass substrate has a substantially disc shape and is formed into a substantially cylindrical shape by laminating, and the polishing brush has a substantially cylindrical shape, and the rotation axes of the glass substrate and the polishing brush are arranged substantially in parallel and face each other at a contact point. Polishing may be performed by rotating to move in the direction. This is for efficiently polishing the disk-shaped glass substrate for a magnetic disk.

  The glass substrate for magnetic disk may be made of aluminosilicate glass. In such a case, a good glass substrate for a magnetic disk can be obtained.

  A typical configuration of the magnetic disk manufacturing method according to the present invention is characterized in that at least a magnetic layer is formed on the surface of the magnetic disk glass substrate obtained by the method for manufacturing a magnetic disk glass substrate. Thereby, a magnetic disk having extremely high smoothness and flatness can be manufactured.

  According to the present invention, it is possible to reliably perform mirror polishing to the depth of the groove formed by the adjacent chamfered portions and keep the chamfered portion angle within the standard. Accordingly, the yield can be improved to reduce the production cost, and the particles can be reduced to obtain a highly clean glass substrate, and thus a magnetic disk with high smoothness.

  A polishing brush, a brush adjustment jig, and a method for adjusting a polishing brush according to the present invention will be described with reference to the drawings. Portions that overlap with the above background art will be assigned the same reference numerals and descriptions thereof will be omitted. In the present embodiment, specific numerical values will be given to facilitate understanding of the invention, but the present invention is not limited to this.

  As described with reference to FIG. 8 in the background art above, conventionally, the chamfered portion is not sufficiently polished at the back of the groove formed by the adjacent chamfered portions 12 or the side wall portions 11 are largely polished. The angle α has become larger.

  The inventors thought that the back of the chamfered portion 12 could not be polished because the tip of the polishing brush 2 could not enter. In addition, if the depth of the chamfered portion 12 can be efficiently polished, the side wall portion 11 will not be polished more than necessary, and the chamfered portion angle α can be prevented from increasing. I thought it would be. And the inventors thought that it would be possible to polish to the back of the chamfered portion 12 by sharpening the tips of the fibers 20 of the polishing brush 2.

(Brush tip of polishing brush)
FIG. 1 is a view for explaining a state in which an end surface of a glass substrate is polished using a polishing brush (hereinafter referred to as an adjustment brush 4) having a thin fiber tip. The adjustment brush 4 has the same configuration as that of the polishing brush 2 described in the conventional example except that the tip of the hair is thinned. The adjustment brush 4 is made of a nylon fiber having a diameter of 0.2 mm, and the outer shape is substantially cylindrical. And the outer peripheral surface is a polished surface.

  As shown to Fig.1 (a), the fiber 40 of the adjustment brush 4 is formed in the shape where a diameter becomes small toward a hair tip. Thereby, as shown in FIG.1 (b), the fiber 40 contact | abutted to the side wall part 11 of the end surface 10 is easy to bend, and a hair tip reaches | attains easily in the groove | channel formed by the adjacent chamfering part 12. FIG. Further, since the hair tips are thin and sharp, the inner part of the groove can be rubbed sufficiently. As a result, the side wall portion 11 and the chamfered portion 12 can be polished to the same extent, and excessive polishing of the side wall portion 11 can be prevented and sufficient mirror polishing of the chamfered portion 12 can be achieved.

  FIG. 2 is a diagram comparing the chamfered portion angle α when using the conventional polishing brush 2 and the adjustment brush 4 in which the tips of the fibers 40 are made thin, and the surface properties by an electron microscope. As shown in the figure, the chamfered portion angle α is 48.2 ° when the conventional polishing brush 2 is used, but it is 45.8 when the adjusting brush 4 according to this embodiment is used. It became °. This is very close to 45 ° which is the center of the standard defined as 40 to 50 °. When the surface texture of the chamfered portion is seen, it is understood that the surface is mirror-polished to the back of the chamfered portion and the surface property is also improved.

  Next, the shape of the hair tip in a state where it can be optimally polished was observed by changing the fineness of the hair tip. FIG. 3 is a diagram illustrating the shape of the hair tip. FIG. 3A is a photograph using six fibers 40 as a sample, and FIG. 3B is a diagram showing the relationship between the distance from the tip read from the photograph and the thickness of the fiber. In addition, about the distance from a front-end | tip and the thickness of a fiber, length was measured on the photograph and it converted on the basis of the diameter (0.2 mm) of the part which the fiber has not shaved.

As can be seen from FIG. 3 (b), the length from the tip of the portion where the diameter decreases toward the fiber tip (the portion that has been cut into a substantially conical shape) is a minimum of 1.333 mm and a maximum of It was 2.889 mm. If the cross section in the length direction of the bristles is approximated to be a triangle, the average cross-sectional area in the range of the length was 0.156 mm ^{2 to} 0.311 mm ² .

  However, the hair tip has a spindle shape that becomes thinner as it goes to the tip. In addition, if the fiber diameter (the diameter of the original uncut portion) changes, the cross-sectional area also changes. However, if the fiber has the same sharpness, the effect of the present invention can be obtained. Therefore, when the cross section in the length direction of the portion where the diameter decreases toward the fiber tip is regarded as a triangle, the base (thickness, always the original diameter) and height in the same range as the above cross-sectional area. The ratio of (length from the tip) may be 7.780 to 15.555.

(Jig for brush adjustment)
As a jig for thinning the tip of the fiber 40 of the adjustment brush 4, it is also conceivable to use a glass substrate (glass dummy) that is not a product. However, when a glass dummy was used, it took 10 to 12 hours to polish the fibers 40 of the adjustment brush 4 into a desired shape. Further, using glass as a product as a jig is expensive and wears quickly, so that the number of adjustments is small, and there is a problem that it takes time and effort to stack the glass substrates into a cylindrical shape. Therefore, a jig that can adjust the hair tips more efficiently at low cost is required.

  FIG. 4 is a diagram illustrating the configuration of the brush adjustment jig. As shown in the figure, the adjustment jig 5 is made of aluminum and has a substantially cylindrical shape, and a large number of circumferential grooves 50 are arranged on the outer peripheral surface. The groove 50 has a substantially V-shaped cross section, a pitch of 2 mm, a depth of 1.73 mm, and an opening angle of about 60 °. The diameter of the adjusting jig 5 is 100 mm for the adjusting brush 4 for polishing a 2.5-inch substrate (φ65 mm), and for the adjusting brush 4 for polishing a 1-inch substrate (φ27.4 mm). Was 60 mm.

  As a study of the material of the adjustment jig 5, aluminum is used in the above configuration. However, since the adjustment jig 5 is also deformed by wear, the adjustment jig made of aluminum material can be used only about 48 times. Then, the optimum material for the adjustment jig was next determined and stainless steel (SUS304) was used. This is because stainless steel is harder and more durable than aluminum.

  However, the bristles of the brush adjusted with stainless steel were not sharpened to the desired shape, and the yield was lower in the experiment than when adjusted with aluminum. This is considered because the polishing ability is low because stainless is denser than aluminum. It was also found that the speed of wear was not related to the hardness of the metal, and the life reached unexpectedly about 40 times. Therefore, it was found that aluminum was more suitable as the material for the adjustment jig 5 than stainless steel. If aluminum is the main material, it may be an alloy mixed with other metals in order to increase rigidity and toughness.

(Polishing brush adjustment method)
The adjustment jig 5 was adjusted by attaching the adjustment jig 5 to the end surface polishing apparatus shown in FIG. 8 instead of the laminated glass substrate 1 and adjusting the adjustment brush 4. Therefore, the adjustment brush 4 and the adjustment jig 5 rotate relatively with their axes parallel to each other, so that the fiber 40 is polished, the tip of the fiber 40 is worn, and the diameter thereof is directed toward the tip. It can be made smaller. Thus, adjustment can be performed without using a dedicated device.

  FIG. 5 is a diagram in which the adjustment time of the adjustment brush 4 is examined using the adjustment jig 5. As shown in the figure, before adjustment, the hair tip has the same diameter up to the tip and is angular. Then, after adjusting for 45 minutes, the hair ends burned and fell. On the other hand, when the adjustment was performed for 20 minutes, the hair tip was thin and sharp, and a desired shape could be obtained. That is, according to the above configuration, the polishing brush 4 can be adjusted quickly and efficiently, and the ends of the fibers 40 can be polished into a desired shape in about 20 minutes.

  By the way, if the end surface of a glass substrate is grind | polished using the adjustment brush 4, the front-end | tip of the fiber 40 of the adjustment brush 4 will also wear according to it. FIG. 6 is a diagram for explaining a worn tip of the adjusting brush. In particular, a thin hair tip wears quickly, the hair tip becomes round, and a predetermined effect cannot be obtained. In such a case, it is necessary to readjust the hair tip of the adjustment brush 4.

[Example 1]
In this example, a glass substrate for a magnetic disk and a magnetic disk were manufactured through the following steps.

(1) Shape processing step and first lapping step In the method of manufacturing a magnetic disk glass substrate according to this example, first, the surface of the plate glass is lapped (ground) to obtain a glass base material. Cut the material and cut out the glass disc. Various plate glasses can be used as the plate glass. This plate-like glass can be manufactured by using a known manufacturing method such as a press method, a float method, a downdraw method, a redraw method, or a fusion method using a molten glass as a material. Of these, plate glass can be produced at low cost by using the pressing method. As the material of the plate glass, amorphous glass or glass ceramics (crystallized glass) can be used. As the material for the plate glass, aluminosilicate glass, soda lime glass, borosilicate glass, or the like can be used. In particular, as an amorphous glass, an aluminosilicate glass can be preferably used in that it can be chemically strengthened and a magnetic disk substrate excellent in flatness of the main surface and substrate strength can be supplied.

In this example, the melted aluminosilicate glass was molded into a disk shape by direct pressing using an upper mold, a lower mold, and a barrel mold to obtain an amorphous plate glass. As the aluminosilicate _glass, SiO 2: 58 to 75 _{wt%, Al} 2 O 3: _{5~23 wt%,} Li 2 O: 3 to 10 _wt%, Na 2 O: 4 to 13 principal component weight% What was contained as was used.

  Next, both main surfaces of the plate glass were lapped to form a disk-shaped glass base material. This lapping process was performed using alumina free abrasive grains with a double-sided lapping apparatus using a planetary gear mechanism. Specifically, the lapping platen is pressed on both sides of the plate glass from above and below, the grinding liquid containing free abrasive grains is supplied onto the main surface of the plate glass, and these are moved relative to each other for lapping. went. By this lapping process, a glass base material having a flat main surface was obtained. Moreover, the plate | board thickness of the glass base material was reduced rather than plate glass by this lapping process, and became 0.6 mm.

(2) Cutting process (coring, forming)
Next, the glass base material was cut using a diamond cutter, and a glass substrate having a diameter of 29 mm was cut out from the glass base material. The diameter of the glass base material was 96 mm, and six glass substrates could be collected from one glass base material.

  Next, using a cylindrical diamond drill, a circular hole was formed in the center of the glass substrate to obtain a donut-shaped glass substrate (coring). Then, the inner peripheral end face and the outer peripheral end face were ground with a diamond grindstone and subjected to predetermined chamfering (forming).

(3) End surface polishing process Next, the end surface of the glass substrate was mirror-polished by a brush polishing method. At this time, as the abrasive grains, a slurry (free abrasive grains) containing cerium oxide abrasive grains was used. Next, the inner peripheral side end face was mirror polished by a magnetic polishing method. And the glass substrate which finished the end surface grinding | polishing process was washed with water. By this end surface polishing step, the end surface of the glass substrate was processed into a mirror surface state capable of preventing generation of particles and the like. As a result, the diameter of the glass substrate becomes 27.4 mm, which can be used as a substrate for a 1-inch magnetic disk.

  In this end surface polishing step, the glass substrate is overlapped and the end surface is polished. In this case, in order to avoid scratches on the main surface of the glass substrate, before the first polishing step described later, Alternatively, it may be performed before and after the second polishing step.

  Here, the polishing of the end face 10 was performed using the adjustment brush 4 in which the ends of the fibers 40 were thinned. The adjusting jig 5 is made of aluminum. In addition, the shape, adjustment, and readjustment of the hair tips are as described above.

[Evaluation]
After the end face polishing step, the surface property (whether it was mirror-polished) and the chamfer angle (whether it was within the standard of 40 ° <α <50 °) were confirmed. FIG. 7 is a diagram for explaining the surface properties and rank classification when the conventional polishing brush 2 is used and when the adjustment brush 4 according to this embodiment is used.

  The surface property is inspected by observing with an electron microscope and ranking. Then, as shown in FIG. 7, in the past, rank 1 was about 20% and rank 2 was about 75%. In other words, it is possible to reliably perform mirror polishing to the depth of the groove formed by the adjacent chamfered portions, thereby preventing the generation and adsorption of particles, and obtaining a very clean glass substrate and consequently a magnetic disk with high smoothness. be able to.

  Regarding the chamfered portion angle α, the average of 49.6 ° can be lowered to 47.5 ° on average in the present example.

(4) Second Lapping Step Next, a second lapping process was performed on both main surfaces of the obtained glass substrate in the same manner as in the first lapping step. By performing this second lapping step, it is possible to remove in advance the fine unevenness formed on the main surface in the cutting step and end surface polishing step, which are the previous steps, and shorten the subsequent polishing step on the main surface. Will be able to be completed in time.

(5) Main surface polishing step As the main surface polishing step, first, a first polishing step was performed. This first polishing step is mainly intended to remove scratches and distortions remaining on the main surface in the lapping step described above. In the first polishing step, the main surface was polished using a hard resin polisher by a double-side polishing apparatus having a planetary gear mechanism. As the abrasive, cerium oxide abrasive grains were used.

  The glass substrate that has finished the first polishing step is sequentially immersed in cleaning baths of neutral detergent, pure water (1), pure water (2), IPA (isopropyl alcohol), and IPA (steam drying), and cleaned. did.

  Next, a second polishing step was performed as the main surface polishing step. The purpose of this second polishing step is to finish the main surface into a mirror surface. In the second polishing step, mirror polishing of the main surface was performed using a soft foamed resin polisher by a double-side polishing apparatus having a planetary gear mechanism. As the abrasive, cerium oxide abrasive grains finer than the cerium oxide abrasive grains used in the first polishing step were used.

  After the second polishing process, the glass substrate is made of neutral detergent (1), neutral detergent (2), pure water (1), pure water (2), IPA (isopropyl alcohol), IPA (steam-dried). It was immersed in each washing tank in order and washed. Note that ultrasonic waves were applied to each cleaning tank.

(6) Chemical strengthening process Next, the glass substrate which finished the above-mentioned lapping process and grinding | polishing process was chemically strengthened. For chemical strengthening, a chemical strengthening solution prepared by mixing potassium nitrate (60%) and sodium nitrate (40%) is prepared, and the chemically strengthened solution is heated to 400 ° C., and the cleaned glass substrate is heated to 300 ° C. The sample was preheated and immersed in a chemical strengthening solution for about 3 hours. In this immersion, in order to chemically strengthen the entire surface of the glass substrate, it was carried out in a state of being accommodated in a holder so that a plurality of glass substrates were held at the end surfaces.

  Thus, by immersing in a chemical strengthening solution, the lithium ion and sodium ion of the surface layer of a glass substrate are each substituted by the sodium ion and potassium ion in a chemical strengthening solution, and a glass substrate is strengthened. The thickness of the compressive stress layer formed on the surface layer of the glass substrate was about 100 μm to 200 μm.

  The glass substrate that had been subjected to the chemical strengthening treatment was immersed in a water bath at 20 ° C. for rapid cooling and maintained for about 10 minutes. And the glass substrate which finished quenching was immersed in the concentrated sulfuric acid heated at about 40 degreeC, and was wash | cleaned. Further, the glass substrate after the sulfuric acid cleaning was cleaned by immersing in a cleaning bath of pure water (1), pure water (2), IPA (isopropyl alcohol) and IPA (steam drying) sequentially. In addition, ultrasonic waves were applied to each cleaning tank.

  As described above, by applying the first lapping step, the cutting step, the end surface polishing step, the second lapping step, the first and second polishing steps, the precision cleaning, and the chemical strengthening step, a flat and smooth, high rigidity A glass substrate for a magnetic disk was obtained.

(7) Texture processing step Polishing and circumferential texture processing were performed using a tape-type texture device. A woven fabric type tape was used as the tape, and a slurry in which polycrystalline diamond having an average particle size of 0.1 μm was dissolved in a dispersant / lubricant (glycerin) was used as the hard abrasive. After this texturing step, pre-cleaning with an ultrapure water shower was performed for 5 seconds in order to wash away the diamond slurry and dispersant (lubricant) of the abrasive.

(8) Precision washing process Next, the glass disk in which the texture was formed was precision washed. This is to remove abrasive residues and foreign iron-based contaminants that cause head crush and thermal asperity failure, and to obtain a glass substrate with a smooth surface and a clean surface. This precision cleaning process includes the following series of cleaning processes.

  First, a cleaning process using a cleaning solution was performed. In this cleaning solution, a chemical solution in which KOH and NaOH were mixed at a ratio of 1: 1 was diluted with ultrapure water, and a nonionic surfactant was added to enhance the cleaning ability. The pH of the cleaning liquid was adjusted to 12.4 by diluting ultrapure water. The glass disk was immersed in this cleaning solution and then washed for 2 minutes while rocking. At this time, the temperature of the cleaning liquid was set to 50 ° C., and ultrasonic waves were applied to enhance the cleaning effect.

  Next, the water rinse washing | cleaning process was performed for 2 minutes. This is for removing the residue of the cleaning liquid used in the above-described cleaning. Then, the IPA washing process was performed for 2 minutes. This is for cleaning the glass disk and removing water on the substrate. Finally, the IPA vapor drying process was performed for 2 minutes. This is for drying while removing the liquid IPA adhering to the substrate with the IPA vapor.

(9) Magnetic disk manufacturing process A seed layer, Cr underlayer, CrMo underlayer, CoPtCrTa magnetic layer, hydrogenation on both surfaces of the glass substrate textured through the above-described steps using a single-wafer sputtering apparatus. A carbon protective layer was formed, and a perfluoropolyether lubricating layer was formed by a dip method to produce a magnetic disk.

  The obtained magnetic disk was confirmed to be free from defects in the film such as the magnetic layer due to foreign matter. In addition, when the glide test was performed, no hit (the head bited against the protrusion on the surface of the magnetic disk) or crash (the head collided with the protrusion on the surface of the magnetic disk) was not recognized. Furthermore, when a reproduction test was conducted with a magnetoresistive head, no malfunction of reproduction due to thermal asperity was found.

  The present invention can be used as a method for producing a glass substrate and a magnetic disk for a magnetic recording medium.

It is a figure explaining a mode that the end surface of a glass substrate is grind | polished. It is a figure explaining the surface property by chamfering part angle (alpha) and an electron microscope. It is a figure explaining the shape of a hair end. It is a figure explaining the structure of the jig | tool for brush adjustment. It is the figure which examined the adjustment time of the adjustment brush. It is a figure explaining the hair | bristle tip with which the adjustment brush was worn. It is a figure explaining surface property and ranking. It is a figure explaining the end surface grinding | polishing apparatus of a board | substrate. It is a principal part enlarged view explaining the mode of the conventional end surface grinding | polishing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Glass substrate 2 ... Polishing brush 3 ... Nozzle 4 ... Adjustment brush 5 ... Adjustment jig 10 ... End surface 11 ... Side wall part 12 ... Chamfering part 20, 40 ... Fiber 50 ... Groove

Claims (15)

A plurality of glass substrates each having a chamfered portion and a side wall portion formed on an end surface, and a polishing brush for polishing the end surface,
The outer shape is substantially cylindrical, and the outer peripheral surface is a polished surface,
A polishing brush, characterized in that the fibers forming the brush are formed in a shape whose diameter decreases toward the tip of the hair. ^2. The polishing brush according to claim 1, wherein an average cross-sectional area of a cross-section forming a substantially triangular portion of the portion whose diameter decreases toward the fiber tip is 0.156 mm ^{2 to} 0.311 mm ^2. . The polishing brush according to claim 1, wherein a ratio of a base of a substantially triangular shape and a height of a cross section of a portion whose diameter decreases toward the fiber tip is 7.780 to 15.555. The polishing brush according to claim 1, wherein the fiber is made of nylon. 2. The polishing brush according to claim 1, wherein the fiber has a diameter of about 0.2 mm. The polishing brush according to claim 1, wherein the magnetic disk glass substrate is made of aluminosilicate glass. The polishing brush polishes a glass substrate for a magnetic disk mounted on a 1-inch hard disk drive or a hard disk drive using a magnetic disk having a smaller diameter than the 1-inch hard disk drive. Polishing brush. A jig for adjusting the hair tip of the polishing brush according to any one of claims 1 to 7,
The jig is substantially cylindrical and has a large number of circumferential grooves arranged on the outer peripheral surface.
By polishing by rotating relatively with the polishing brush parallel to the shaft, the fiber tip of the polishing brush is worn, and the fiber diameter is reduced toward the tip. Brush adjustment jig. The brush adjusting jig according to claim 8, wherein the groove has a substantially V-shaped cross section, a pitch of 2 mm, a depth of 1.73 mm, and an opening angle of about 60 °. 9. The brush adjusting jig according to claim 8, wherein the main material is aluminum. The brush adjustment jig according to any one of claims 8 to 10 is mounted on a glass substrate polishing apparatus in place of the laminated glass substrates, and any one of claims 1 to 7. A method for adjusting a polishing brush, comprising adjusting a polishing brush. Laminating a plurality of glass substrates having chamfered portions and side wall portions on the end surfaces,
A method for producing a glass substrate for a magnetic disk, characterized in that the end face is polished with a polishing brush made of a fiber having a diameter that decreases toward a hair end. The glass substrate has a substantially disc shape and is formed into a substantially cylindrical shape by stacking,
The polishing brush is substantially cylindrical,
13. The glass substrate for a magnetic disk according to claim 12, wherein the glass substrate and the polishing brush are disposed so as to be substantially parallel to each other, and polishing is carried out by rotating the glass substrate and the polishing brush so as to move in opposite directions. Manufacturing method. The method for manufacturing a glass substrate for a magnetic disk according to claim 12, wherein the glass substrate is made of aluminosilicate glass. A magnetic disk comprising at least a magnetic layer formed on a surface of a glass substrate for a magnetic disk obtained by the method for manufacturing a glass substrate for a magnetic disk according to any one of claims 12 to 14. Production method.