WO2014178417A1 - 磁気ディスク用ガラス基板の製造方法及び磁気ディスクの製造方法、並びに磁気ディスク用ガラス基板の端面研磨装置 - Google Patents
磁気ディスク用ガラス基板の製造方法及び磁気ディスクの製造方法、並びに磁気ディスク用ガラス基板の端面研磨装置 Download PDFInfo
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- WO2014178417A1 WO2014178417A1 PCT/JP2014/062031 JP2014062031W WO2014178417A1 WO 2014178417 A1 WO2014178417 A1 WO 2014178417A1 JP 2014062031 W JP2014062031 W JP 2014062031W WO 2014178417 A1 WO2014178417 A1 WO 2014178417A1
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- glass substrate
- magnetic
- polishing
- side wall
- generating means
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B9/00—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor
- B24B9/02—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground
- B24B9/06—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain
- B24B9/065—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain of thin, brittle parts, e.g. semiconductors, wafers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B31/00—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor
- B24B31/10—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor involving other means for tumbling of work
- B24B31/112—Machines or devices designed for polishing or abrading surfaces on work by means of tumbling apparatus or other apparatus in which the work and/or the abrasive material is loose; Accessories therefor involving other means for tumbling of work using magnetically consolidated grinding powder, moved relatively to the workpiece under the influence of pressure
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B9/00—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor
- B24B9/02—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground
- B24B9/06—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain
- B24B9/08—Machines or devices designed for grinding edges or bevels on work or for removing burrs; Accessories therefor characterised by a special design with respect to properties of materials specific to articles to be ground of non-metallic inorganic material, e.g. stone, ceramics, porcelain of glass
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
- G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
Definitions
- the present invention relates to a method for manufacturing a glass substrate for a magnetic disk used in a magnetic disk mounted on a magnetic recording device such as a hard disk drive (hereinafter abbreviated as “HDD”) and a method for manufacturing a magnetic disk.
- a hard disk drive hereinafter abbreviated as “HDD”
- a magnetic disk as one of information recording media mounted on a magnetic recording apparatus such as an HDD.
- a magnetic disk is configured by forming a thin film such as a magnetic layer on a substrate, and an aluminum substrate has been conventionally used as the substrate.
- the ratio of the glass substrate capable of narrowing the distance between the magnetic head and the magnetic disk as compared with the aluminum substrate is gradually increasing.
- the surface of the glass substrate is polished with high accuracy so as to increase the recording density so that the flying height of the magnetic head can be reduced as much as possible.
- HDDs high recording capacity and lower prices. In order to achieve this, it is necessary to further improve the quality and cost of glass substrates for magnetic disks. It is coming.
- a glass substrate for a magnetic disk is usually produced by sequentially performing steps such as shape processing (end grinding and chamfering), end surface polishing, main surface grinding, main surface polishing, chemical strengthening on a glass substrate formed into a disk shape. .
- shape processing end grinding and chamfering
- end surface polishing main surface grinding
- main surface polishing chemical strengthening
- chemical strengthening on a glass substrate formed into a disk shape.
- Patent Document 1 As disclosed in the following Patent Document 1, conventionally, the end surface of a glass substrate for a magnetic disk is generally processed by polishing the end surface using a grindstone and then polishing the end surface of the brush. It was.
- Patent Document 2 below discloses a method of polishing an end surface of a glass substrate for a magnetic disk by applying a magnetic field to a slurry containing ferrite magnetic particles and abrasive grains.
- Patent Document 3 below discloses a magnetic fluid (magnetic powder) that is attracted to a magnetic electrode by rotating a magnetic electrode disposed away from the processing surface of the workpiece relative to the workpiece. A magnetic polishing method for processing a workpiece with held abrasive grains is disclosed.
- the end face of the substrate is improved in quality based on a request to reduce contamination factors such as the occurrence of corrosion on the main surface of the medium. It is required to achieve both improvement in shape accuracy to reduce flutter (flutter).
- the chamfered surface of the end surface of the glass substrate is used.
- the processing rate is different from that of the side wall surface, and it is difficult to finish both the chamfered surface and the side wall surface into a mirror surface within a predetermined processing time.
- both the chamfered surface and the side wall surface are processed until they are finished to a mirror surface, there arises a problem that the processing time is increased and the shape accuracy is deteriorated.
- the above-mentioned Patent Document 3 does not disclose the end face polishing of the magnetic disk glass substrate.
- the present invention improves the shape accuracy of the end surface of the magnetic disk glass substrate particularly from the viewpoint of meeting the demand for higher recording density of magnetic disks, which is urgently required to ensure high recording density.
- Another object of the present invention is to provide a method for producing a glass substrate for a magnetic disk capable of stable processing that can be finished with high quality, and a method for producing a magnetic disk using the glass substrate obtained thereby.
- the present invention has the following configuration.
- (Configuration 1) A method of manufacturing a glass substrate for a magnetic disk including an end surface processing for processing an end surface of a disk-shaped glass substrate having a main surface, wherein the end surface processing includes magnetism generating means comprising a pair of opposed magnets.
- the magnetic lines of force are formed, and the magnetic slurry containing the magnetic particles and the abrasive grains is held by the magnetic lines of force to form a lump of the magnetic slurry along the lines of magnetic force, in a plane direction perpendicular to the direction of the lines of magnetic force.
- a method for manufacturing a glass substrate for a magnetic disk comprising: an end surface polishing process for simultaneously polishing both surfaces of at least one chamfered surface between the two.
- (Configuration 2) The method for manufacturing a glass substrate for a magnetic disk according to Configuration 1, wherein an inclination angle of the glass substrate is in a range of 10 degrees to 45 degrees.
- (Configuration 3) The method for manufacturing a glass substrate for a magnetic disk according to Configuration 1 or 2, wherein an inclination angle of the glass substrate is changed during processing.
- (Configuration 4) 3. The method of manufacturing a glass substrate for a magnetic disk according to Configuration 1 or 2, wherein the tilt angle of the glass substrate is changed continuously or stepwise with a processed portion of the glass substrate as a center.
- a method of manufacturing a glass substrate for a magnetic disk including an end face processing for processing an end face of a disk-shaped glass substrate, wherein the end face processing is performed by applying magnetic lines of force using magnetism generating means composed of a pair of opposed magnets.
- the magnetic slurry containing magnetic particles and abrasive grains is held by the magnetic lines of force to form a lump of the magnetic slurry along the lines of magnetic force, and the end surface of the glass substrate is brought into contact with the lump of magnetic slurry.
- An end surface polishing process for polishing both the side wall surface of the end surface of the glass substrate and at least one chamfered surface between the main surface of the glass substrate and the side wall surface,
- a method of manufacturing a glass substrate for a magnetic disk including an end face processing for processing an end face of a disk-shaped glass substrate, wherein the end face processing is performed by applying magnetic lines of force using magnetism generating means composed of a pair of opposed magnets.
- the magnetic slurry containing magnetic particles and abrasive grains is held by the magnetic lines of force to form a lump of the magnetic slurry along the lines of magnetic force, and the end surface of the glass substrate is brought into contact with the lump of magnetic slurry.
- An end surface polishing process for polishing both the side wall surface of the end surface of the glass substrate and at least one chamfered surface between the main surface of the glass substrate and the side wall surface, Using a first magnetism generating means for mainly polishing one chamfered surface and a side wall surface, and a second magnetism generating means for mainly polishing the other chamfered surface and the side wall surface of the glass substrate,
- the first magnetic generation Method of manufacturing a glass substrate for a magnetic disk wherein the a stage second magnetism generating means for the orientation of each of the magnetic field lines are arranged differently.
- the second magnetism generating means includes a magnetism generating means for mainly polishing a chamfered surface between one main surface and a side wall surface of the glass substrate, and a chamfer between the other main surface and the side wall surface. 6.
- Configuration 8 Before the end surface polishing process, a grinding process is performed to form both chamfered surfaces and side wall surfaces on the end surface of the glass substrate, and the grinding process is performed with respect to an axis orthogonal to the main surface of the glass substrate.
- Any one of configurations 1 to 7 including a grinding process of grinding the end surface of the glass substrate by bringing the grinding wheel into contact with the end surface of the glass substrate in a state where the rotation axis of the grinding wheel is inclined.
- a magnetic disk manufacturing method comprising forming at least a magnetic recording layer on a magnetic disk glass substrate manufactured by the method for manufacturing a magnetic disk glass substrate according to any one of Structures 1 to 8.
- a magnetic force line is formed using a magnetism generating means composed of a pair of magnets arranged opposite to each other, and a magnetic slurry containing magnetic particles and abrasive grains is held by the magnetic force line, thereby forming the magnetic slurry mass along the magnetic force line. And forming an end face of the disk-shaped glass substrate in contact with the lump of the magnetic slurry, and chamfering at least one of the side wall surface of the end face of the glass substrate and the main surface of the glass substrate and the side wall face.
- An apparatus for polishing an end surface of a glass substrate for a magnetic disk used for an end surface polishing process that polishes both surfaces of the glass substrate, the first magnetism generating means for mainly polishing a side wall surface of the glass substrate, and the glass substrate A second magnetism generating means for mainly polishing the chamfered surface, wherein the first magnetism generating means and the second magnetism generating means are arranged so that the directions of the lines of magnetic force thereof are different from each other.
- a magnetic force line is formed using a magnetism generating means composed of a pair of magnets arranged opposite to each other, and a magnetic slurry containing magnetic particles and abrasive grains is held by the magnetic force line, thereby forming the magnetic slurry mass along the magnetic force line. And forming an end face of the disk-shaped glass substrate in contact with the lump of the magnetic slurry, and chamfering at least one of the side wall surface of the end face of the glass substrate and the main surface of the glass substrate and the side wall face.
- An end surface polishing apparatus for a glass substrate for a magnetic disk used for an end surface polishing process for polishing both of the first surface and a first magnetism for mainly polishing one chamfered surface and a side wall surface of the glass substrate.
- FIG. 1 It is sectional drawing which shows the end surface shape of the glass substrate for magnetic discs.
- (A)-(c) is a figure for demonstrating the end surface grinding
- (A) And (b) is a schematic diagram for demonstrating other embodiment of the state which is each performing the end surface grinding
- FIG. 1 is a cross-sectional view of the outer peripheral end of a magnetic disk glass substrate 1 to which the present invention is applied.
- the glass substrate 1 is not shown in FIG. 1, the whole having a circular hole in the center is formed in a disc shape, and is formed between the main surfaces 11, 11 on the front and back sides and between these main surfaces 11, 11.
- the end surface on the outer peripheral side of the glass substrate 1 has a side wall surface 12a orthogonal to the main surface 11 and two chamfered surfaces formed between the side wall surface 12a and the front and back main surfaces 11, 11 ( Chamfered surfaces) 12b and 12b.
- the side wall surface orthogonal to the main surface 11 and the main surfaces 11 and 11 of this side wall surface and front and back Are formed in a shape composed of two chamfered surfaces (chamfered surfaces) formed between the two.
- the glass substrate 1 is finished to have an outer diameter of 65 mm and an inner diameter of 20 mm.
- the inner diameter is a diameter of a circular hole at the center of the glass substrate 1.
- the main surface 11, the outer peripheral side end surface, and the inner peripheral side end surface of the glass substrate 1 for magnetic disk are all polished (mirror polished) so as to finally have a predetermined surface roughness.
- Both the outer peripheral side end surface and the inner peripheral side end surface of the glass substrate 1 are finished to the end surface shape as described above, and the surface roughness is, for example, Rz 0.1 ⁇ m or less and Ra 0.01 ⁇ m or less. It is usually required to be finished.
- the glass substrate 1 for a magnetic disk is usually subjected to grinding / polishing (mirror polishing) of the end surface, grinding / mirror polishing of the main surface, chemical treatment on a glass substrate (glass disk 10) formed into a predetermined disk shape by a direct press or the like. Manufactured with sequential steps such as strengthening.
- a glass substrate glass disk molded into a predetermined disk shape by direct press or the like
- the glass substrate of the final product produced by processing, processing, etc. on this glass disk for convenience of explanation, They are all called glass substrates or magnetic disk glass substrates.
- the end face grinding process will be described.
- the end face grinding can be performed using a so-called general-purpose grindstone.
- This total shape grindstone is formed in a disk shape of a predetermined size, and has a groove shape for forming the end face shape of the glass substrate on the outer peripheral side thereof.
- the glass substrate The groove shape is such that the shape of both the side wall surface and the chamfered surface can be transferred to the outer peripheral side end surface.
- This total shape grindstone is formed in a predetermined dimensional shape in consideration of the target dimensional shape of the ground surface of the glass substrate.
- a so-called electrodeposition bond grindstone in which diamond abrasive grains, which are high-rigidity grindstones are hardened by electrodeposition bond, is preferable as the overall grindstone used in the end face grinding.
- a resin bond grindstone in which the binder for bonding abrasive grains is a resin material such as phenol resin, urethane resin, polyimide resin, polyester resin, fluororesin, or the binder is copper-based, for example.
- Metal bond grindstones that are metallic binders such as alloys, cast iron alloys, and titanium alloys, and vitrified grindstones whose binder is a vitreous binder are suitable, and a composite grindstone in which these binders are mixed is used. You can also. Among these, a resin bond grindstone in which the adjustment of the hardness of the grindstone is relatively easy is particularly suitable.
- abrasive grains alumina abrasive grains, cubic boron nitride abrasive grains, and the like can be used.
- abrasive grains having an average grain diameter of 30 ⁇ m or less are suitable in order to maintain the grinding performance over the life of the grinding wheel while maintaining the roughness.
- Abrasive grains having an average particle diameter of 2 to 15 ⁇ m are preferred.
- a diamond abrasive grain is suitable, for example.
- the particle size of the abrasive grains can be measured by, for example, an electrical resistance test method.
- the processing is performed in an arrangement relationship in which the glass substrate and the grindstone are in the same plane.
- the peripheral speed and the peripheral speed ratio of each of the grindstone and the glass substrate are appropriately set so as to be suitable for the grinding of the inner and outer peripheral side end faces. It only has to be set.
- the rotating direction of the grindstone and the glass substrate may be either the same direction (counter direction) or a different direction (anti-counter direction) in the processed portion.
- the grinding fluid (coolant) used in the present invention is not particularly limited, but a water-soluble grinding fluid having a high cooling effect and high safety at the production site is particularly suitable.
- the shape of the chamfered surface and the side wall surface of the substrate end surface can be created.
- a precision grinding method after rough grinding using a general-purpose grinding wheel Applying a method of grinding the end face of the glass substrate by bringing the grindstone into contact with the end face of the glass substrate in a state where the rotation axis of the grindstone is inclined with respect to an axis orthogonal to the main surface of the glass substrate. Is preferred.
- a precision grinding process is performed in a state where the grindstone is inclined with respect to a glass substrate in which both the side wall surface and the chamfered surface are formed on the inner and outer peripheral end faces by rough grinding using a general-purpose grindstone.
- the grindstone used in this case is formed in a disk shape of a predetermined size, and has a groove shape on the outer peripheral side thereof in contact with the end surface of the glass substrate. It has a concave shape. Unlike the above-mentioned general shape grindstone, shape transfer is performed using a part of the groove shape.
- the grindstone used in the processing method for performing precision grinding in a state where the grindstone is inclined with respect to such a glass substrate it is preferable to apply the above-mentioned resin bond grindstone.
- the processing while rotating the grindstone and the glass substrate in respective predetermined directions, and the respective peripheral speeds and peripheral speed ratios may be appropriately set so as to be suitable for processing of the inner and outer peripheral side end faces.
- the rotating direction of the grindstone and the glass substrate may be either the same direction (counter direction) or a different direction (anti-counter direction) in the processed portion.
- the grindstone that comes into contact with the end surface of the glass substrate by bringing the grindstone into contact with the end surface of the glass substrate in a state where the rotation axis of the grindstone is inclined with respect to the axis orthogonal to the main surface of the glass substrate.
- the processing is performed by bringing the end face of the glass substrate into contact with the grindstone so that the trajectory is not constant.
- the trajectory of the grindstone that comes into contact with the end surface of the glass substrate is not constant, and the convex portions (abrasive grains) of the grindstone abut and act on the substrate end surface at random positions. There is little damage, and the surface roughness and in-plane variation of the ground surface are reduced, so that the ground surface with the above-described general-purpose grindstone can be finished to a higher smoothness (quasi-mirror surface state).
- an end surface polishing process using a magnetic slurry containing a magnetorheological fluid and abrasive grains is performed.
- the end polishing process using this magnetic slurry is capable of high-quality polishing, but the lower the roughness of the ground surface after the pre-processing (pre-processing), the smaller the allowance for the end polishing process using the magnetic slurry. can do. If the roughness after grinding is high and the machining allowance is large, a deviation from the shape created by grinding may occur, and for example, the roundness of the edge may become larger than the specification. Therefore, as described above, it is preferable to finish the substrate end surface in a quasi-mirror surface state by precision grinding with the grindstone tilted with respect to the glass substrate before the end surface polishing treatment using the magnetic slurry.
- One embodiment of the end surface polishing treatment of the present invention is to form a linear or arc-shaped magnetic field line that proceeds in the thickness direction of the glass substrate using a magnetism generating means composed of a pair of opposed magnets,
- the magnetic slurry containing the magnetorheological fluid and the abrasive grains is held by the magnetic lines of force to form a lump of the magnetic slurry along the magnetic lines of force, and the glass substrate has a surface direction perpendicular to the direction of the magnetic lines of force.
- the end surface of the glass substrate With the main surface (horizontal plane) inclined, the end surface of the glass substrate is brought into contact with the lump of the magnetic slurry, and the side wall surface of the end surface of the glass substrate and between the main surface of the glass substrate and the side wall surface This is a process of polishing both surfaces of at least one chamfered surface at the same time.
- FIGS. 2A to 2C are diagrams for explaining the end surface polishing treatment of the present invention.
- FIG. 3 is a perspective view for explaining the end surface polishing process of the present invention
- FIG. 4 is a schematic view for explaining a state in which the end surface polishing process of the embodiment of the present invention is performed.
- the apparatus 20 used for the end face polishing process in the present invention polishes the end face of the glass substrate using a magnetism generating means and a magnetic slurry.
- FIGS. 2 (a) to 2 (c), FIGS. 3 and 4 all show a case where the outer peripheral end face of the glass substrate is polished.
- the apparatus 20 includes a pair of magnets 21 and 22 that are permanent magnets, a spacer 23, and a hollow cylinder made of a nonmagnetic material such as stainless steel. Shape-shaped exterior member 24. Magnets 21 and 22 and a spacer 23 are built in the exterior member 24. If it is desired to increase the amount of contact between the magnetic slurry and the glass substrate in order to adjust the polishing rate, etc., it is necessary to insert the end portion of the glass substrate between the magnets 21 and 22 so that the exterior member 24 is processed. It is preferable not to provide.
- the glass substrate 10 that has been subjected to the end surface grinding is held by a holder (not shown).
- the glass substrate 10 held by the holding tool is brought close to the apparatus 20, and a magnetic slurry lump 26 (see FIGS. 2C and 3) described later is brought into contact with the outer peripheral side end surface of the glass substrate 10.
- a holder (not shown) that holds the apparatus 20 and the glass substrate 10 is connected to a drive motor (not shown). By rotating the apparatus 20 and the holder to relatively move the outer peripheral side end face of the glass substrate 10 and the lump 26 of the magnetic slurry, the outer peripheral end face of the glass substrate 10 can be polished.
- the rotation direction of the apparatus 20 and the holder for holding the glass substrate 10 are rotated in opposite directions (see FIG. 3), It is preferable to rotate the glass substrate 10 at a peripheral speed relative to, for example, 50 to 500 m / min. At this time, the relative speed of 100 to 400 m / min is more preferable because the processing rate increases.
- the magnetic slurry lump 26 may be fixed as long as the outer peripheral side end face of the glass substrate 10 and the magnetic slurry lump 26 can be relatively moved.
- the pair of magnets 21 and 22 are close to each other and function as magnetism generating means to form magnetic lines 25 as shown in FIG.
- the magnetic field lines 25 are linear magnetic field lines that proceed from the centers of the magnets 21 and 22 in the thickness direction of the glass substrate.
- a pair of magnets arranged in the thickness direction of the glass substrate 10 so that the N-pole surface and the S-pole surface are spaced apart from each other is used as the magnetism generating means. It is done.
- a spacer 23 made of a non-magnetic material is provided between the magnets 21 and 22 in order to set a predetermined separation distance between the N pole end face of the magnet 21 and the S pole end face of the magnet 22. It has been.
- a lump of magnetic slurry may be formed between the magnets 21 and 22, and the end of the glass substrate may be brought into contact therewith. Since the magnetic slurry lump 26 is a portion that contacts the outer peripheral side end surface of the glass substrate 10 and moves relative to the end surface, the magnetic slurry lump 26 has a certain degree of magnetic force in order to ensure the rigidity of the magnetic slurry lump 26. Is desired. For this reason, it is preferable that the separation distance between the end face of the N pole of the magnet 21 and the end face of the S pole of the magnet 22 is short, but if it is too short, it becomes difficult to carry out when inserting the glass substrate between the magnets. Therefore, it is preferable that the separation distance between the end face of the N pole of the magnet 21 and the end face of the S pole of the magnet 22 is set within a certain predetermined range.
- a permanent magnet is used as the magnetism generating means.
- the spacer 23 is used in order to ensure a constant distance between the N pole end face of the magnet 21 and the S pole end face of the magnet 22, the magnets 21 and 22 are used without using the spacer 23. Can be secured, and the separation distance between the end face of the N pole of the magnet 21 and the end face of the S pole of the magnet 22 can be kept constant.
- a magnetic particle (magnetic fine particles) dispersed in a dispersion medium is used.
- the magnetic particles may be any ferromagnetic material, and particles containing iron element (Fe) are preferable from the viewpoint of particularly strong magnetic force. Moreover, you may use what mixed iron type and ferromagnetic materials other than iron type.
- the particle size of the magnetic particles is preferably within the range of 0.1 to 10 ⁇ m. By setting it as the said range, a grinding
- the dispersion medium nonpolar oil or polar oil can be suitably used.
- the dispersion medium When nonpolar oil or polar oil is used as the dispersion medium, for example, it is preferable that the dispersion medium has a viscosity of 100 to 1000 (mPa ⁇ sec) at room temperature (20 ° C.).
- a surfactant may be added to the magnetorheological fluid.
- abrasive grains contained in the magnetic slurry known abrasive grains of glass substrates such as cerium oxide, colloidal silica, zirconium oxide, alumina, and diamond can be used.
- the particle size of the abrasive grains is, for example, 0.5 to 3 ⁇ m. By using abrasive grains having a particle size in this range, the end face of the glass substrate can be satisfactorily polished.
- the abrasive grains are preferably contained in the magnetic slurry, for example, about 3 to 15% by volume.
- the viscosity of the magnetic slurry is preferably 1000 to 2000 mPa ⁇ sec at room temperature (20 ° C.) by adjusting the concentration of the magnetorheological fluid from the viewpoint of forming the magnetic slurry lump 26 and efficiently polishing the end face. If the viscosity is low (the concentration of the magnetorheological fluid is low), it is difficult to form the lump 26, and it is difficult to perform relative movement while being pressed against the end face of the glass substrate 10 for polishing. On the other hand, when the viscosity of the magnetic slurry is excessively high, it is difficult to form a uniform pressed state.
- the magnetic flux density in the magnetism generating means is preferably 0.3 to 0.8 Tesla from the viewpoint that the magnetic slurry lump 26 is formed and the end face polishing is performed efficiently. Further, the yield stress of the magnetic slurry containing the magnetorheological fluid and the abrasive grains is preferably 30 kPa or more and more preferably 30 to 60 kPa when a 0.4 Tesla magnetic field is applied.
- the yield stress (yield shear stress) of the magnetorheological fluid can be obtained by, for example, the following method.
- a magnetic field application means permanent magnet, electromagnet, etc.
- the yield stress of the magnetorheological fluid can be obtained by approximating the relationship between the shear stress and the shear stress using a known Casson equation.
- the yield stress affects the pressure that the glass substrate receives from the magnetic slurry, that is, the shear stress when the magnetic slurry held by the magnetic field and the edge of the glass substrate move relative to each other. Therefore, the higher the yield stress of the magnetic slurry (the higher the shear stress during the magnetic slurry flow), the more efficiently the polishing by contact between the abrasive grains and the glass substrate can be achieved, and the processing rate can be improved.
- the main surface of the glass substrate is inclined with respect to the plane direction perpendicular to the direction of the magnetic lines of force formed by the magnetism generating means composed of a pair of magnets arranged opposite to each other.
- polishing is performed by bringing the end face of the glass substrate into contact with a lump of magnetic slurry.
- the main surface L0 of the glass substrate 10 is angled with respect to a plane direction L1 perpendicular to the direction of the magnetic lines of force formed so as to advance linearly between a pair of magnets 21 and 22 arranged opposite to each other.
- the end surface of the glass substrate is brought into contact with a lump of magnetic slurry while being inclined by ⁇ (the magnetic slurry is not shown in FIG. 4). And by performing the said operation with respect to two chamfering surfaces, an end surface can be grind
- the side wall surface of the end surface of the glass substrate is more Since the contact pressure with the magnetic slurry is higher than the chamfered surface, the processing rate of the side wall surface is larger than the processing rate of the chamfered surface, and the side wall surface is processed faster.
- the processing rate differs between the chamfered surface and the side wall surface of the glass substrate end surface, it is difficult to finish both the chamfered surface and the side wall surface to the same quality within a predetermined processing time. In this case, if both the chamfered surface and the side wall surface are processed to the same quality, the processing time becomes longer and the shape accuracy of the edge between the preferentially processed side wall surface and the chamfered surface deteriorates. Problem arises.
- the contact between the chamfered surface of the substrate end surface and the magnetic slurry is promoted by inclining the main surface of the glass substrate with respect to the surface direction orthogonal to the direction of the magnetic lines of force.
- it is possible to suppress the difference in processing rate between the chamfered surface and the side wall surface of the glass substrate end surface, and it is possible to finish both the chamfered surface and the side wall surface to the same quality mirror surface within a predetermined processing time. It becomes.
- the shape accuracy of both the chamfered surface and the side wall surface of the glass substrate end surface is improved, the shape accuracy of the edge between the side wall surface and the chamfered surface is improved, and the end surface has high quality and high accuracy. Stable polishing can be achieved.
- the inclination angle ⁇ of the glass substrate is slightly different depending on the distance between the magnets and the magnetic flux density, but is preferably in the range of, for example, 10 ° to 45 °. If the inclination angle of the glass substrate is less than 10 degrees, it may be difficult to obtain the effect of suppressing the difference in processing rate between the chamfered surface and the side wall surface of the end surface of the glass substrate. On the other hand, when the inclination angle of the glass substrate is larger than 45 degrees, there may be a problem that the radius of curvature of the edge between the main surface and the chamfered surface is deteriorated.
- the end surface polishing treatment of the present invention it is possible to finish both the chamfered surface and the side wall surface into a mirror surface of the same quality within a predetermined processing time.
- the shape accuracy of both surfaces of the wall surface can be improved.
- the variation in the curvature radius of the edge between the chamfered surface and the side wall surface of the glass substrate and the variation in the curvature radius of the edge between the main surface and the chamfered surface of the glass substrate are both. It can be within 0.05 mm, more preferably within 0.03 mm.
- the present invention is not limited to the embodiment in which the polishing process is performed in a state where the inclination angle of the glass substrate is fixed to a predetermined angle as described above.
- the inclination angle of the glass substrate is continuously or stepwise within a predetermined range (for example, 10 to 30 degrees). It is also possible to carry out the polishing process while changing to. Also, for example, the polishing process can be performed while changing the range of plus 30 degrees to minus 30 degrees continuously or stepwise.
- the locus of the polishing abrasive grains does not overlap, so that the surface roughness after polishing can be reduced. Moreover, since the time for changing the angle in the middle can be omitted, productivity can be improved.
- the machining allowance by the end surface polishing treatment in the present invention is preferably 1 to 10 ⁇ m in terms of diameter. Further, if the thickness is 5 ⁇ m or less, the shape accuracy is further improved, which is further preferable.
- polishing of the outer peripheral side end surface of the glass substrate 10 was demonstrated above, it can grind
- the end face processing including end face polishing using the magnetic slurry in the present invention is equivalent to a thick plate (for example, 0.635 mm or more) even if the glass substrate thickness to be input into the end face processing is, for example, 0.5 mm or less.
- the end face quality can be secured.
- a magnetic force generation means comprising a pair of magnets arranged opposite to each other is used to form linear magnetic lines of force, and the magnetic slurry containing the magnetorheological fluid and the abrasive grains is added to the magnetic slurry.
- the magnetic slurry lump is formed along the lines of magnetic force, the end surface of the glass substrate is brought into contact with the magnetic slurry lump, the side wall surface of the end surface of the glass substrate, and the glass substrate.
- This is a process of polishing both the main surface and the chamfered surface between the side wall surfaces, but the characteristic configuration in the present embodiment is the processing rate of the chamfered surface and the side wall surface of the glass substrate end surface. Is to polish the end face of the glass substrate by using a plurality of magnetism generating means having different directions of magnetic lines of force so that they are equal.
- FIG. 5 is a schematic view for explaining another embodiment of the state where the end surface polishing treatment of the present invention is performed, and shows a case where the outer peripheral side end surface of the glass substrate is polished. Note that the apparatus used for the end surface polishing process of the present embodiment is the same as that of the above-described embodiment, and thus description thereof is omitted here.
- a first magnetism generating unit that mainly polishes the side wall surface of the glass substrate and a second magnetism generating unit that mainly polishes the chamfered surface of the glass substrate are used.
- the first magnetism generating means and the second magnetism generating means are arranged so that the directions of the magnetic lines of force are different from each other.
- the glass substrate 10 is fixed at a predetermined position during processing, and is disposed between a pair of opposed magnets 21 and 22 constituting the first magnetism generating means.
- the magnetic field lines formed so as to proceed in a straight line mainly contact the side wall surface of the glass substrate 10, and the first magnetism generating means is arranged so that the side wall surface can be polished efficiently.
- the glass substrate 10 is fixed in the same position as that shown in FIG.
- the magnetic field lines formed so as to proceed in a straight line form mainly contact with the chamfered surface of the glass substrate 10 and the second magnetism generating means is arranged so that the chamfered surface can be polished efficiently.
- the magnetic slurry is not shown.
- the first magnetism generating unit that mainly polishes the side wall surface of the glass substrate 10 and the second magnetism generating unit that mainly polishes the chamfered surface of the glass substrate 10.
- the first magnetism generating means and the second magnetism generating means are arranged so that the directions of the magnetic lines of force are different from each other.
- a single magnetism generating means is used to insert a glass substrate in a direction perpendicular to the direction of the magnetic force lines, and the end surface of the glass substrate is attached to the magnetic slurry.
- polishing is performed in contact with a lump of material (the same state as in (a))
- the side wall surface of the glass substrate end surface has a larger amount of contact with the magnetic slurry than the chamfered surface. The rate becomes larger than the processing rate of the chamfered surface, and the side wall surface is processed preferentially.
- the first magnetism generating means for mainly polishing the side wall surface of the glass substrate 10 and the second magnetism generating means for mainly polishing the chamfered surface of the glass substrate 10 are used.
- the first magnetism generating means is arranged so that the magnetic field lines formed mainly contact the side wall surface of the glass substrate 10, and the side wall surface can be efficiently polished.
- the magnetic field lines to be formed are arranged so as to mainly contact the chamfered surface of the glass substrate 10 and efficiently polish the chamfered surface.
- the processing rate is equal between the chamfered surface and the side wall surface of the glass substrate end surface, it becomes possible to finish both the chamfered surface and the side wall surface to the same quality mirror surface within a predetermined processing time.
- the first magnetism generating means for mainly polishing the side wall surface of the glass substrate 10 and the second magnetism generating means for mainly polishing the chamfered surface of the glass substrate 10 around the glass substrate 10, respectively.
- Both the side wall surface and the chamfered surface of the glass substrate 10 can be polished at the same time.
- the processing time is longer than this, for example, the side wall surface of the glass substrate is first polished using the first magnetic generation means, and then the glass substrate is polished using the second magnetic generation means.
- the chamfered surface may be polished.
- the end surface of the glass substrate 10 actually has a chamfered surface between one main surface and the side wall surface and a chamfered surface between the other main surface and the side wall surface.
- the second magnetism generating means includes a magnetism generating means for mainly polishing a chamfered surface between one main surface and a side wall surface of the glass substrate, and the other It is desirable to provide a magnetism generating means for mainly polishing a chamfered surface between the main surface and the side wall surface, and to arrange the magnetic field lines in different directions.
- the end surface of the glass substrate is polished using three magnetism generating means having different magnetic force lines so that one side wall surface and two chamfered surfaces of the glass substrate end surface can be polished. It is preferable to do.
- these several magnetism generation means are arrange
- the glass substrate is used by using a plurality of magnetism generating units having different magnetic force lines so that the processing rates of the chamfered surface and the side wall surface of the glass substrate end surface are equal.
- polishing the end face it is possible to finish both the chamfered surface and the side wall surface to the same quality mirror surface within a predetermined processing time, and both the chamfered surface and the side wall surface of the glass substrate end surface can be finished. Shape accuracy can be improved.
- the variation in the radius of curvature of the edge between the chamfered surface and the side wall surface of the glass substrate and the variation in the radius of curvature of the edge between the main surface and the chamfered surface of the glass substrate after the end surface polishing treatment of the present embodiment can be accommodated within 0.03 mm.
- the machining allowance by the end surface polishing process in the above-described embodiment is about 1 to 10 ⁇ m. Further, if the thickness is 5 ⁇ m or less, the shape accuracy is further improved, which is further preferable.
- a first magnetism generating unit that mainly polishes one chamfered surface and a side wall surface of the glass substrate, and the other of the glass substrate.
- the second magnetism generating means that mainly polishes the chamfered surface and the side wall surface is used, and the first magnetism generating means and the second magnetism generating means are arranged so that the directions of the magnetic lines of force are different from each other. This is also a preferred embodiment.
- the end surface polishing treatment of such an embodiment it is possible to finish both the chamfered surface and the side wall surface into a mirror surface of the same quality within a predetermined processing time, and the chamfered surface and side of the glass substrate end surface The shape accuracy of both surfaces of the wall surface can be improved. Also, there is an advantage that two magnetism generating means are required to finish the processing at one time.
- polishing of the outer peripheral side end surface of the glass substrate 10 was demonstrated above, it can grind
- one magnetism generating means is disposed in, for example, the state of FIG. 5A to polish the side wall surface of the glass substrate, Subsequently, it is possible to polish the chamfered surface of the glass substrate by arranging the same magnetism generating means in the state of FIG.
- the present invention also provides an end surface polishing apparatus for a magnetic disk glass substrate having the following configuration. That is, a magnetic force line is formed using a pair of magnets arranged opposite to each other, and a magnetic slurry containing magnetic particles and abrasive grains is held by the magnetic force line.
- An end surface polishing apparatus for a glass substrate for a magnetic disk used for an end surface polishing process for polishing both the chamfered surface and the first magnetism generating means for mainly polishing a side wall surface of the glass substrate;
- Second magnetism generating means for mainly polishing the chamfered surface of the glass substrate, and the first magnetism generating means and the second magnetism generating means are arranged so that the directions of the magnetic lines of force are different from each other.
- a magnetic force line is formed using a pair of magnets arranged opposite to each other, and a magnetic slurry including magnetic particles and abrasive grains is held by the magnetic force line, so that the magnetic slurry is moved along the magnetic force line.
- An end surface polishing apparatus for a glass substrate for a magnetic disk used for an end surface polishing process for polishing both surfaces with a chamfered surface, wherein a first chamfered surface and a side wall surface of the glass substrate are mainly polished.
- Magnetic generation means, and second magnetic generation means for mainly polishing the other chamfered surface and the side wall surface of the glass substrate, wherein the first magnetic generation means and the second magnetic generation means
- the direction of each magnetic field line is different Providing also an end face polishing apparatus for a glass substrate for a magnetic disk, characterized in that it is urchin arranged.
- the glass constituting the glass substrate is preferably an amorphous aluminosilicate glass.
- a glass substrate can be finished to a smooth mirror surface by mirror polishing the surface, and the strength after processing is good.
- an aluminosilicate glass for example, a glass containing SiO 2 as a main component and containing 20 wt% or less of Al 2 O 3 is preferable. Furthermore, it is more preferable to use glass containing SiO 2 as a main component and containing 15% by weight or less of Al 2 O 3 .
- SiO 2 is 62 wt% to 75 wt%
- Al 2 O 3 is 5 wt% to 15 wt%
- Li 2 O is 4 wt% to 10 wt%
- Na 2 O is 4 wt%.
- % To 12% by weight, ZrO 2 is contained in an amount of 5.5% to 15% by weight as a main component, and the weight ratio of Na 2 O / ZrO 2 is 0.5 to 2.0
- Al 2 O An amorphous aluminosilicate glass containing no phosphorus oxide and having a 3 / ZrO 2 weight ratio of 0.4 to 2.5 can be used.
- SiO 2 is 50 to 75%
- Al 2 O 3 is 0 to 5%
- BaO is 0 to 2%
- Li 2 O is 0 to 3%
- ZnO 0-5% Na 2 O and K 2 O 3-15% in total
- ZrO 2 , TiO 2 , La 2 O 3 , Y 2 O 3 , Yb 2 O 3 , Ta 2 O 5 , Nb 2 O 5 and HfO 2 are included in a total amount of 2 to 9%
- the molar ratio [(MgO + CaO) / (MgO + CaO + SrO + BaO)] is in the range of 0.85 to 1.
- And glass having a molar ratio [Al 2 O 3 / (MgO + CaO)] of 0 to 0.30 can be preferably used. Further, a total of 6 to 15 mol of an alkali metal oxide selected from the group consisting of 56 to 75 mol% of SiO 2 , 1 to 9 mol% of Al 2 O 3 , Li 2 O, Na 2 O and K 2 O.
- the content of Al 2 O 3 in the glass composition is preferably 15% by weight or less. Furthermore, still preferably Al 2 O 3 content is 5 mol% or less.
- this glass substrate is subjected to grinding (lapping) of the main surface for improving dimensional accuracy and shape accuracy.
- This main surface grinding is usually performed by using a double-sided lapping machine to grind the main surface of the glass substrate using hard abrasive grains such as diamond.
- a double-sided lapping machine to grind the main surface of the glass substrate using hard abrasive grains such as diamond.
- this lapping step may be performed before the end surface grinding process is performed on the disk-shaped glass disk produced by the direct press method described above.
- the mirror polishing process for obtaining a highly smooth main surface is performed.
- a mirror polishing method for a glass substrate it is preferable to use a polishing pad of a polisher such as polyurethane while supplying a slurry (polishing liquid) containing a metal oxide abrasive such as cerium oxide or colloidal silica. is there.
- a glass substrate having high smoothness is obtained, for example, by polishing with a cerium oxide-based abrasive (first polishing process) and then with final polishing (mirror polishing) (second polishing process) using colloidal silica abrasive grains. It is possible.
- Ra and Rz are roughnesses in accordance with Japanese Industrial Standard (JIS) B0601: 2001.
- the surface roughness for example, maximum roughness Rz, arithmetic average roughness Ra
- the surface roughness of the side wall surface and the chamfered surface is measured in a measurement region of 50 ⁇ m ⁇ 50 ⁇ m using a laser microscope with an observation magnification of 3000 times. It is a measured value.
- chemical strengthening treatment may be performed to improve the substrate strength.
- a method of the chemical strengthening treatment for example, a low-temperature ion exchange method in which ion exchange is performed in a temperature range not exceeding the glass transition temperature is preferable.
- the chemical strengthening treatment is a process in which a molten chemical strengthening salt is brought into contact with a glass substrate, whereby an alkali metal element having a relatively large atomic radius in the chemical strengthening salt and a relatively small atomic radius in the glass substrate.
- This is a treatment in which an alkali metal element is ion-exchanged, an alkali metal element having a large ion radius is permeated into the surface layer of the glass substrate, and compressive stress is generated on the surface of the glass substrate.
- the chemically strengthened glass substrate is excellent in impact resistance, it is particularly preferable for mounting on a HDD for mobile use, for example.
- the chemical strengthening salt alkali metal nitrates such as potassium nitrate and sodium nitrate can be preferably used.
- the magnetic disk glass substrate according to the present invention is manufactured.
- the present invention also provides a method for producing a magnetic disk using the above glass substrate for a magnetic disk.
- the magnetic disk is manufactured by forming at least a magnetic layer on the magnetic disk glass substrate according to the present invention.
- a material for the magnetic layer a hexagonal CoCrPt-based or CoPt-based ferromagnetic alloy having a large anisotropic magnetic field can be used.
- a method of forming the magnetic layer it is preferable to use a method of forming a magnetic layer on a glass substrate by a sputtering method, for example, a DC magnetron sputtering method.
- the orientation direction of the magnetic grains of the magnetic layer and the size of the magnetic grains can be controlled.
- a cubic base layer such as a Cr-based alloy
- the magnetization easy direction of the magnetic layer can be oriented along the magnetic disk surface.
- a magnetic disk of the in-plane magnetic recording system is manufactured.
- a hexagonal underlayer containing Ru or Ti for example, the easy magnetization direction of the magnetic layer can be oriented along the normal of the magnetic disk surface.
- a perpendicular magnetic recording type magnetic disk is manufactured.
- the underlayer can be formed by sputtering as with the magnetic layer.
- a protective layer and a lubricating layer may be formed in this order on the magnetic layer.
- the protective layer an amorphous hydrogenated carbon-based protective layer is suitable.
- the protective layer can be formed by a plasma CVD method.
- a lubricant having a functional group at the end of the main chain of the perfluoropolyether compound can be used.
- the main component is a perfluoropolyether compound having a terminal hydroxyl group as a polar functional group.
- the lubricating layer can be applied and formed by a dip method.
- the end surface of the substrate is finished with a high precision shape and high quality, so that the occurrence of failures due to the surface state of the substrate end surface, such as anti-corrosion, is prevented.
- a higher recording density can be realized, and a highly reliable magnetic disk can be obtained.
- Examples 1 to 6, Comparative Example 1 The following (1) substrate preparation step, (2) main surface grinding step, (3) end surface grinding step, (4) end surface polishing step, (5) main surface polishing step (first polishing step), (6) chemical strengthening A glass substrate for a magnetic disk of this example was manufactured through steps (7) and a main surface polishing step (second polishing step).
- a glass substrate made of disc-shaped aluminosilicate glass having a diameter of 66 mm ⁇ and a thickness of 0.635 mm is obtained from molten glass by direct pressing using an upper mold, a lower mold, and a trunk mold. It was.
- a disk-shaped glass substrate may be obtained by cutting out with a grinding wheel from a sheet glass formed by a downdraw method or a float method.
- SiO 2 62 to 75% by weight
- ZrO 2 5.5 to 15% by weight
- Al 2 O 3 5 to 15% by weight
- Li 2 O 4 to 10% by weight
- Na 2 O Glass for chemical strengthening containing 4 to 12% by weight was used.
- the shape of the chamfered surface was formed so that the angle with respect to the main surface was 45 degrees and the edges were dropped so as to be 150 ⁇ m in the main surface direction and the plate thickness direction, respectively.
- the kind of grindstone, the particle size, etc. selected and used appropriately.
- the surface roughness of the outer peripheral side end surface of the glass substrate at this time was 1.2 ⁇ m or less in terms of Rz for both the side wall surface and the chamfered surface.
- the inner peripheral side end face of the substrate was chamfered using a predetermined total-type grindstone.
- the rotation direction, the rotation speed of the grindstone or magnetic slurry lump, the rotation of the substrate, the relative ratio of the rotation speed of the substrate and the grindstone (or lump of magnetic slurry) in the end face grinding process and the end face polishing process, and the magnet About magnetic flux density etc. it set suitably within the range as described in the above-mentioned embodiment.
- the inclination angle ⁇ of the glass substrate was set in the range of 5 to 60 degrees (see Table 1 below).
- the polishing allowance is set to be 10 ⁇ m in diameter (that is, 5 ⁇ m deep from the surface), and after polishing for 5 ⁇ m, once the glass substrate is removed, the polishing process is stopped, the inclination angle is changed to minus ⁇ , and the remaining 5 ⁇ m. Polished.
- the substantial polishing time was 30 seconds in total.
- the glass substrate was processed in the same manner except that the glass substrate was not tilted (tilt angle was 0 degree). In this way, the outer peripheral end face of the glass substrate was polished.
- a first polishing process for removing scratches and distortions remaining in the main surface grinding process (lapping) described above was performed using a double-side polishing apparatus.
- a glass substrate held by a carrier is closely attached between an upper and lower polishing surface plate to which a polishing pad is attached, and this carrier is engaged with a sun gear (sun gear) and an internal gear (internal gear).
- the glass substrate is sandwiched between upper and lower surface plates.
- a polishing liquid is supplied and rotated between the polishing pad and the polishing surface of the glass substrate, whereby the glass substrate revolves while rotating on the surface plate to simultaneously polish both surfaces.
- the glass substrate after the first polishing step was washed and dried.
- the second polishing step was performed using the same double-side polishing apparatus as used in the first polishing step.
- the surface roughness of the main surface of the glass substrate is 0.2 nm in terms of Ra (measured with an atomic force microscope) while maintaining the flat surface obtained in the first polishing step described above.
- the glass substrate after the second polishing step was washed and dried.
- an edge portion (A in FIG. Variation of the curvature radius between the substrates (Max-Min) was evaluated by a stylus type contour shape measuring machine. First, the curvature radius of the edge part is measured for each board on one board and the average value thereof is calculated. The same measurement is performed on 100 boards, and the maximum value and the minimum value are obtained from the 100 pieces of data obtained. The difference (Max-Min) was calculated and taken as variation.
- Table 1 shows the case where the variation is 0.03 mm or less as ⁇ , the case where it is larger than 0.03 mm and 0.05 mm or less as ⁇ , and the case where the variation is larger than 0.05 mm as x. If the variation is 0.05 mm or less, it is practically acceptable.
- the curvature of the edge portion was evaluated as an evaluation of the edge angle variation between the main surface and the chamfered surface on the outer peripheral end face of the substrate after the end face polishing.
- Radius variation (Max-Min) was evaluated by a stylus type contour shape measuring machine in the same manner as described above. The results are shown in Table 2, where ⁇ is a variation of 0.02 mm or less, ⁇ is greater than 0.02 mm and 0.03 mm or less, and ⁇ is greater than 0.03 mm and 0.05 mm or less.
- the variation in the curvature radius of the edge can be made 0.05 mm or less by inclining the glass substrate. Further, in Examples 2 to 4 where the glass substrate was polished while being tilted within a range of 10 to 45 degrees, the edge between the chamfered surface and the side wall surface of the glass substrate after the end surface polishing treatment was performed. The variation in the curvature radius and the variation in the curvature radius of the edge between the main surface and the chamfered surface of the glass substrate were all within 0.03 mm, and better shape accuracy was obtained.
- Example 1 in which the inclination angle is smaller than the above range, and Examples 5 and 6 in which the inclination angle is larger than the above range, the variation in the curvature radius of the edge between the chamfered surface and the side wall surface of the glass substrate varies. Slightly larger. 2.
- Comparative Example 1 in which the polishing process was performed without tilting the glass substrate, there was no problem with the variation in the radius of curvature of the edge between the main surface and the chamfered surface of the glass substrate. Since the processing is difficult to proceed, the variation in the curvature radius of the edge between the chamfered surface and the side wall surface of the glass substrate becomes large, and good shape accuracy cannot be obtained.
- the machining rate differs between the chamfered surface and the side wall surface, and both the chamfered surface and the side wall surface could not be finished to the same quality mirror surface within a predetermined processing time. This is probably due to this.
- the time required for finishing both the chamfered surface and the side wall surface to a mirror surface having the same quality required about twice as long in Comparative Example 1 as compared with the time in Example 3.
- the difference in processing rate between the chamfered surface and the side wall surface is small, and it is possible to finish both the chamfered surface and the side wall surface with the same quality in substantially the same processing time.
- the processing rate is different between the chamfered surface and the side wall surface. Therefore, both the chamfered surface and the side wall surface cannot be finished to the same quality in a short time, and the processing rate is low.
- Example 3 when the range of plus 20 degrees to minus 20 degrees was continuously changed (reciprocated) in 1 reciprocation 2 seconds, the curvature of the edge between the chamfered surface and the side wall surface was obtained.
- the variation in radius was evaluated as “ ⁇ ”.
- the same result was obtained.
- the grinding process performed before the end surface polishing treatment the grinding process was performed without inclining the grindstone with respect to the glass substrate surface (the polishing allowance is the same). As a result, the maximum value of the surface roughness Ra of the end surface was 0. Although slightly increased to 12 ⁇ m, the variation in edge curvature radius was the same.
- Examples A and B Comparative Example A
- polishing using a magnetic slurry was performed according to the method shown in FIG. As shown in FIG. 5, a lump of magnetic slurry was formed between these two magnets using a polishing apparatus incorporating magnetism generating means composed of a pair of magnets. And the end surface of the glass substrate was grind
- one of the magnetism generating means (magnetism generating means # 1) having the above configuration is arranged at the position shown in FIG.
- the base (magnet generation means # 2) is arranged at the position shown in FIG. 5B, and another one (magnet generation means # 3) of the magnetic generation means having the above configuration is shown in FIG. 5B.
- the magnetic generating means (# 2) is turned upside down and arranged so as to emit magnetic lines of force along the lower chamfered surface in FIG. 5B. In the end face grinding process and the end face polishing process, the rotation direction, the rotation speed of the grindstone or magnetic slurry lump, the rotation of the substrate, the relative ratio between the rotation speed of the substrate and the grindstone (or lump of magnetic slurry), and the magnetic flux density of the magnet Etc.
- the side wall surface and the chamfered surface of the outer peripheral end surface of the glass substrate were simultaneously polished.
- the surface roughness of the outer peripheral end surface of the substrate after processing was 0.1 ⁇ m or less in terms of Rz for both the side wall surface and the chamfered surface.
- polishing brush As described above, the glass substrate after the end face polishing was washed.
- one of the magnetism generating means having the above-described configuration is disposed at a position where one chamfered surface and the side wall surface of the glass substrate are mainly polished, and the magnetism generating means having the above-described configuration The other one was placed in a position where the other chamfered surface and the side wall surface of the glass substrate were mainly polished, and the end surface polishing of the glass substrate was performed in the same manner as in Example A above.
- a glass substrate for a magnetic disk was obtained (Example B).
- a glass substrate was inserted in a direction perpendicular to the direction of the magnetic force lines by using one magnetism generating means, and the end surface of the glass substrate was polished ( A glass substrate for a magnetic disk was obtained in the same manner as in the above example except that the same as in the state of FIG. In this comparative example, the polishing was performed by extending the time until the surface roughness of the side wall surface and the chamfered surface of the glass substrate end face became equal.
- Example A in which the end surface of the glass substrate was polished using three magnetism generating means having different magnetic field lines so that the processing rates of the chamfered surface and the side wall surface of the glass substrate end surface were equal, after end surface polishing processing Both the variation in the curvature radius of the edge between the chamfered surface and the side wall surface of the glass substrate and the variation in the curvature radius of the edge between the main surface and the chamfered surface of the glass substrate can be kept within 0.03 mm. Good shape accuracy was obtained. The same results as in Example A were obtained for Example B using two magnetic generation means. 2. On the other hand, in Comparative Example A in which one magnetism generating means is arranged in the state of FIG.
- the radius of curvature of the edge between the chamfered surface and the side wall surface of the glass substrate is polished, the radius of curvature of the edge between the chamfered surface and the side wall surface of the glass substrate.
- Both the variation and the variation in the radius of curvature of the edge between the main surface and the chamfered surface of the glass substrate were large, and good shape accuracy could not be obtained.
- the machining rate differs between the chamfered surface and the side wall surface, and the shape accuracy deteriorates because the chamfered surface and the side wall surface are processed to the same quality. It is thought that.
- the time required to finish both the chamfered surface and the side wall surface to the same quality mirror surface was approximately twice as long in Comparative Example A as compared to the processing time in Example A.
- the chamfered surface and the side wall surface have the same processing rate, and it is possible to finish both the chamfered surface and the side wall surface with the same quality in substantially the same processing time.
- the machining rate differs between the chamfered surface and the side wall surface, and both the chamfered surface and the side wall surface cannot be finished to the same quality within the same machining time, and the machining time until the chamfered surface with the slower machining rate is finished to the mirror surface. Becomes longer.
- the following film forming process was performed on the magnetic disk glass substrate obtained in Example 3 to obtain a magnetic disk for perpendicular magnetic recording. That is, an adhesion layer made of a Ti-based alloy thin film, a soft magnetic layer made of a CoTaZr alloy thin film, an underlayer made of a Ru thin film, a perpendicular magnetic recording layer made of a CoCrPt alloy, a carbon protective layer, and a lubricating layer are sequentially formed on the glass substrate. A film was formed.
- the protective layer is for preventing the magnetic recording layer from deteriorating due to contact with the magnetic head, and is made of hydrogenated carbon, and provides wear resistance.
- the lubricating layer was formed by dipping a liquid lubricant of alcohol-modified perfluoropolyether.
- the obtained magnetic disk was installed in an HDD equipped with a DFH head, and a load / unload durability test was conducted for one month while operating the DFH function in a high temperature and high humidity environment of 80 ° C. and 80% RH. In particular, there were no obstacles caused by fluttering and corrosion, and good results were obtained.
- Glass substrate for magnetic disk 10 Disc-shaped glass substrate (glass disk) DESCRIPTION OF SYMBOLS 11 Main surface 12 of glass substrate Peripheral side end surface 12a of glass substrate Side wall surface 12b Chamfering surface 20 End surface polishing device 21, 22 Magnet 23 Spacer 24 Exterior member 25 Magnetic field line 26 Magnetic slurry lump
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Abstract
Description
上記のように安価で高記録密度を達成できる磁気ディスクが求められているが、磁気ディスクの高記録密度化のためには、ガラス基板の加工精度にも高度なものが要求されており、それはガラス基板の主表面のみならず、端面形状においても同様である。
また、下記特許文献2には、フェライト系磁性粒子と研磨砥粒を含むスラリに磁場を加えることにより、磁気ディスク用ガラス基板の端面を研磨する方法が開示されている。
また、下記特許文献3には、被加工物の加工面と離間して配置された磁気電極を被加工物と相対的に回転させ、磁気電極に吸引されている磁性流体(磁性粉体)が保持している砥粒により被加工物を加工する磁気研磨方法が開示されている。
(構成1)
主表面を有する円盤状のガラス基板の端面を加工する端面加工処理を含む磁気ディスク用ガラス基板の製造方法であって、前記端面加工処理は、対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、前記磁力線の方向と直交する面方向に対して前記ガラス基板の主表面を傾斜させた状態で前記ガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を同時に研磨する端面研磨処理を含むことを特徴とする磁気ディスク用ガラス基板の製造方法。
前記ガラス基板の傾斜角度は、10度~45度の範囲内であることを特徴とする構成1に記載の磁気ディスク用ガラス基板の製造方法。
(構成3)
加工の途中で前記ガラス基板の傾斜角度を変化させることを特徴とする構成1又は2に記載の磁気ディスク用ガラス基板の製造方法。
(構成4)
前記ガラス基板の加工部を中心にして前記ガラス基板の傾斜角度を連続的又は段階的に変化させることを特徴とする構成1又は2に記載の磁気ディスク用ガラス基板の製造方法。
円盤状のガラス基板の端面を加工する端面加工処理を含む磁気ディスク用ガラス基板の製造方法であって、前記端面加工処理は、対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、前記ガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理を含み、前記ガラス基板の側壁面を主に研磨する第1の磁気発生手段と、前記ガラス基板の面取面を主に研磨する第2の磁気発生手段を用い、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されることを特徴とする磁気ディスク用ガラス基板の製造方法。
円盤状のガラス基板の端面を加工する端面加工処理を含む磁気ディスク用ガラス基板の製造方法であって、前記端面加工処理は、対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、前記ガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理を含み、前記ガラス基板の一方の面取面と側壁面とを主に研磨する第1の磁気発生手段と、前記ガラス基板の他方の面取面と側壁面とを主に研磨する第2の磁気発生手段とを用い、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されることを特徴とする磁気ディスク用ガラス基板の製造方法。
前記第2の磁気発生手段は、前記ガラス基板の一方の主表面と側壁面との間の面取面を主に研磨する磁気発生手段と、他方の主表面と側壁面との間の面取面を主に研磨する磁気発生手段とを備え、各々の磁力線の向きが異なるように配置されることを特徴とする構成5に記載の磁気ディスク用ガラス基板の製造方法。
(構成8)
前記端面研磨処理の前に、前記ガラス基板の端面に面取面と側壁面の両方の面を形成する研削処理を行い、該研削処理は、前記ガラス基板の主表面と直交する軸に対して研削砥石の回転軸を傾斜させた状態で当該研削砥石を前記ガラス基板の端面に当接させて当該ガラス基板の端面を研削する研削処理を含むことを特徴とする構成1乃至7のいずれかに記載の磁気ディスク用ガラス基板の製造方法。
構成1乃至8のいずれかに記載の磁気ディスク用ガラス基板の製造方法により製造された磁気ディスク用ガラス基板上に、少なくとも磁気記録層を形成することを特徴とする磁気ディスクの製造方法。
対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、円盤状のガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理に使用する磁気ディスク用ガラス基板の端面研磨装置であって、前記ガラス基板の側壁面を主に研磨する第1の磁気発生手段と、前記ガラス基板の面取面を主に研磨する第2の磁気発生手段とを備え、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されていることを特徴とする磁気ディスク用ガラス基板の端面研磨装置。
(構成11)
対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、円盤状のガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理に使用する磁気ディスク用ガラス基板の端面研磨装置であって、前記ガラス基板の一方の面取面と側壁面とを主に研磨する第1の磁気発生手段と、前記ガラス基板の他方の面取面と側壁面とを主に研磨する第2の磁気発生手段とを備え、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されていることを特徴とする磁気ディスク用ガラス基板の端面研磨装置。
図1は、本発明が適用される磁気ディスク用ガラス基板1の外周側端部の断面図である。該ガラス基板1は、図1には示されていないが、中心部に円孔を有する全体が円盤状に形成され、その表裏の主表面11,11と、これら主表面11,11間に形成される外周側の端面と内周側の端面を有する。
なお、本発明においては、ダイレクトプレス等により所定の円板状に成形したガラスディスクから、このガラスディスクに加工、処理等を施して作製される最終製品のガラス基板にいたるまで、説明の便宜上、すべてガラス基板もしくは磁気ディスク用ガラス基板と呼ぶこととする。
通常、上記端面研削加工は、所謂総形砥石を用いて行うことができる。
この総形砥石は、所定の大きさの円盤状に形成されており、その外周側には、ガラス基板の端面形状を形成するための溝形状を有しており、具体的には、ガラス基板の外周側端面に側壁面と面取り面の両方の面を形状転写できるような溝形状となっている。この総形砥石は、ガラス基板の研削加工面の仕上がり目標の寸法形状を考慮して、所定の寸法形状に形成されている。
このようなガラス基板に対して砥石を傾けた状態で精密研削する加工法において用いられる砥石としては、上述のレジンボンド砥石を適用することが好適である。
この加工方法では、ガラス基板の端面に当接する砥石の軌跡が一定とはならないで、砥石の凸部(砥粒)が基板端面に対してランダムな位置に当接、作用するため、基板へのダメージが少なく、研削加工面の表面粗さやその面内ばらつきも小さくなり、上述の総形砥石による研削加工面をより高平滑(準鏡面状態)に仕上げることができる。
本発明の端面研磨処理の一実施の形態は、対向配置された一対の磁石からなる磁気発生手段を用いて前記ガラス基板の厚さ方向に進むような直線状又は円弧状の磁力線を形成させ、磁気粘性流体と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、前記磁力線の方向と直交する面方向に対して前記ガラス基板の主表面(水平面)を傾斜させた状態で前記ガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を同時に研磨する処理である。
本発明における端面研磨処理に用いられる装置20は、磁気を発生させる手段と磁性スラリを用いてガラス基板の端面の研磨を行う。図2(a)~(c)、図3及び図4は、いずれもガラス基板の外周側端面の研磨を行う場合を示している。
なお、研磨レート等の調整を行うべく磁性スラリとガラス基板との接触量を増やしたい場合は、ガラス基板の端部を磁石21、22間に挿入して加工する必要があるので、外装部材24は設けない方が好ましい。
本発明の端面研磨処理の他の実施の形態は、対向配置された一対の磁石からなる磁気発生手段を用いて直線状の磁力線を形成させ、磁気粘性流体と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、ガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の面取面との両方の面を研磨する処理であるが、本実施の形態において特徴的な構成は、ガラス基板端面の面取面と側壁面の加工レートが同等になるように磁力線の向きが異なる複数の磁気発生手段を用いてガラス基板の端面を研磨することである。
なお、本実施の形態の端面研磨処理に用いられる装置については、前述の実施の形態と同様であるので、ここでは説明を省略する。
また、上述の本実施の形態に関連する他の実施の形態として、前記ガラス基板の一方の面取面と側壁面とを主に研磨する第1の磁気発生手段と、前記ガラス基板の他方の面取面と側壁面とを主に研磨する第2の磁気発生手段とを用い、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されることも好適な実施の形態である。このような実施の形態の端面研磨処理によれば、所定の加工時間内で面取面と側壁面の両方を同じ品質の鏡面に仕上ることが可能であり、ガラス基板端面の面取面と側壁面の両方の面の形状精度を向上させることができる。また、1度で加工を終わらせるためには、磁気発生手段が2つで済むという利点もある。
すなわち、対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、円盤状のガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理に使用する磁気ディスク用ガラス基板の端面研磨装置であって、前記ガラス基板の側壁面を主に研磨する第1の磁気発生手段と、前記ガラス基板の面取面を主に研磨する第2の磁気発生手段とを備え、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されていることを特徴とする磁気ディスク用ガラス基板の端面研磨装置である。
また、対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、円盤状のガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理に使用する磁気ディスク用ガラス基板の端面研磨装置であって、前記ガラス基板の一方の面取面と側壁面とを主に研磨する第1の磁気発生手段と、前記ガラス基板の他方の面取面と側壁面とを主に研磨する第2の磁気発生手段とを備え、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されていることを特徴とする磁気ディスク用ガラス基板の端面研磨装置についても提供する。
また、SiO2を56~75モル%、Al2O3を1~9モル%、Li2O、Na2OおよびK2Oからなる群から選ばれるアルカリ金属酸化物を合計で6~15モル%、MgO、CaOおよびSrOからなる群から選ばれるアルカリ土類金属酸化物を合計で10~30モル%、ZrO2、TiO2、Y2O3、La2O3、Gd2O3、Nb2O5およびTa2O5からなる群から選ばれる酸化物を合計で0%超かつ10モル%以下、含むガラスであってもよい。
本発明において、ガラス組成におけるAl2O3の含有量が15重量%以下であると好ましい。さらには、Al2O3の含有量が5モル%以下であるとなお好ましい。
ガラス基板の鏡面研磨方法としては、酸化セリウムやコロイダルシリカ等の金属酸化物の研磨材を含有するスラリー(研磨液)を供給しながら、ポリウレタン等のポリシャの研磨パッドを用いて行うのが好適である。高い平滑性を有するガラス基板は、たとえば酸化セリウム系研磨材を用いて研磨した後(第1研磨加工)、さらにコロイダルシリカ砥粒を用いた仕上げ研磨(鏡面研磨)(第2研磨加工)によって得ることが可能である。
以上のようにして、本発明に係る磁気ディスク用ガラス基板が製造される。
本発明によって得られるガラス基板を利用することにより、基板の端面が高精度形状及び高品質に仕上げられているため、コロージョン対策など、基板端面の表面状態が起因する障害の発生を防止し、より一層の高記録密度化を実現でき、且つ信頼性の高い磁気ディスクを得ることができる。
(実施例1~6、比較例1)
以下の(1)基板準備工程、(2)主表面研削工程、(3)端面研削工程、(4)端面研磨工程、(5)主表面研磨工程(第1研磨工程)、(6)化学強化工程、(7)主表面研磨工程(第2研磨工程)を経て本実施例の磁気ディスク用ガラス基板を製造した。
まず、溶融ガラスから上型、下型、胴型を用いたダイレクトプレスにより直径66mmφ、厚さ0.635mmの円盤状のアルミノシリケートガラスからなるガラス基板(ガラスディスク)を得た。なお、この場合、ダイレクトプレス以外に、ダウンドロー法やフロート法で形成したシートガラスから研削砥石で切り出して円盤状のガラス基板を得てもよい。このアルミノシリケートガラスとしては、SiO2:62~75重量%、ZrO2:5.5~15重量%、Al2O3:5~15重量%、Li2O:4~10重量%、Na2O:4~12重量%を含有する化学強化用ガラスを使用した。
この主表面研削加工は両面ラッピング装置を用い、ダイヤモンドパッドが貼り付けられた上下定盤の間にキャリアにより保持したガラス基板をセットして行ない、所定の板厚に調節した。
(3)端面研削工程
次に、円筒状砥石を用いてガラス基板の中央部分に孔を空けると共に、外周端面および内周端面に所定の端面研削(形状加工)を行った。
本実施例では、まず総型砥石を用いて基板の外周端面を面取り加工した後、さらに前述のガラス基板面に対して砥石を傾けた状態で研削加工を行い、基板端面に面取面および側壁面を形成した。面取面の形状は、主表面に対する角度を45度とし、主表面方向及び板厚方向にそれぞれ150μmとなるようにエッジを落とすように形成した。
なお、砥石の種類、粒度などは適当なものを選択して用いた。
このときのガラス基板の外周側端面の表面粗さは、側壁面、面取面ともにRzで1.2μm以下であった。
また、基板の内周側端面に関しては、所定の総型砥石を用いて面取り加工を施した。
次いで、上記のように研削加工により基板端面に面取面及び側壁面を形成したガラス基板の外周側端面の研磨処理を行った。本実施例では、前述の図4に示す方法に従って磁性スラリを用いる研磨処理を行った。
図4に示すように、一対の磁石からなる磁気発生手段を内蔵した研磨装置を用いて2つの磁石間に磁性スラリの塊を形成させた。そして、これら2つの磁石とガラス基板とを互いに回転させることにより、ガラス基板の端面を研磨した。なお、両者の回転方向は図3に示すように互いに逆方向(加工部においては同方向)とし、加工部における相対速度は200m/分とした。
なお、その他、端面研削工程及び端面研磨工程における、回転方向、砥石又は磁性スラリの塊の回転数、基板の回転、基板と砥石(又は磁性スラリの塊)の回転数の相対比、および磁石の磁束密度等については、上述の実施の形態中に記載の範囲内で適宜設定した。
また、ガラス基板の傾斜角度αは、5度~60度の範囲で設定した(下記表1参照)。研磨取代は直径において10μm(すなわち表面からの深さ5μm)となるように設定し、5μm研磨したところで一旦ガラス基板を離して研磨加工を止め、傾斜角度をマイナスαに変更してから残りの5μmを研磨した。実質的な研磨処理時間は全部で30秒であった。
また、比較例1として、ガラス基板を傾斜させない(傾斜角度ゼロ度)こと以外は同様にして加工した。
こうして、ガラス基板の外周端面の研磨を行った。加工後の基板の外周端面の表面粗さは、側壁面、面取面ともにRzで0.1μm以下であった。
また、ガラス基板の内周側については、従来の研磨ブラシを用いて研磨を行った。
以上のようにして、上記端面研磨を終えたガラス基板を洗浄した。
次に、上述した主表面研削加工(ラッピング)で残留した傷や歪みを除去するための第1研磨工程を両面研磨装置を用いて行なった。両面研磨装置においては、研磨パッドが貼り付けられた上下研磨定盤の間にキャリアにより保持したガラス基板を密着させ、このキャリアを太陽歯車(サンギア)と内歯歯車(インターナルギア)とに噛合させ、上記ガラス基板を上下定盤によって挟圧する。その後、研磨パッドとガラス基板の研磨面との間に研磨液を供給して回転させることによって、ガラス基板が定盤上で自転しながら公転して両面を同時に研磨加工するものである。第1研磨工程を終えたガラス基板を洗浄し、乾燥した。
次に、上記洗浄を終えたガラス基板に化学強化を施した。化学強化は硝酸カリウムと硝酸ナトリウムの混合物を溶融させた化学強化液を用意し、この化学強化溶液にガラス基板を浸漬して化学強化処理を行なった。
次いで上記の第1研磨工程で使用したものと同じ両面研磨装置を用い、第2研磨工程を実施した。この第2研磨工程は、上述した第1研磨工程で得られた平坦な表面を維持しつつ、例えばガラス基板主表面の表面粗さをRa(原子間力顕微鏡での測定値)で0.2nm以下の平滑な鏡面に仕上げるための鏡面研磨加工である。上記第2研磨工程を終えたガラス基板を洗浄し、乾燥した。
また、得られたガラス基板の外径は65mm、内径は20mm、板厚は0.635mmであった。
こうして、本実施例の磁気ディスク用ガラス基板を得た。
そして、得られた磁気ディスク用ガラス基板の側壁面と面取面との粗さ(Rz)をレーザー顕微鏡を用いてそれぞれ計測し、面取面と側壁面との粗さ(Rz)の差を、基板を傾斜させない場合と比べると、基板を傾斜させたもののほうが、上記差が小さいことがわかった。
また、同様にして作製した100枚のガラス基板について、上記端面研磨終了後の基板の外周端面における面取面と側壁面との間のエッジ角度のばらつきの評価として、エッジ部分(図1のA部)の曲率半径の基板間のばらつき(Max-Min)を触針式の輪郭形状測定機によって評価した。まず、1枚の基板について表裏1点ずつエッジ部分の曲率半径を測定してそれらの平均値を算出し、100枚について同様に測定し、得られた100個のデータから最大値と最小値の差(Max-Min)を算出してばらつきとした。ばらつきが0.03mm以下の場合を○、0.03mmより大きく0.05mm以下の場合を△、0.05mmよりも大きい場合を×として、表1に示した。なお、ばらつきが0.05mm以下であれば実用上合格である。
1.上記磁性スラリによる端面研磨処理において、ガラス基板を傾斜させることで、エッジの曲率半径のばらつきを0.05mm以下にすることができる。また、ガラス基板を10度~45度の範囲内で傾斜させた状態で研磨処理を行った実施例2~4においては、端面研磨処理後の、ガラス基板の面取面と側壁面とのエッジの曲率半径のばらつきと、ガラス基板の主表面と面取面とのエッジの曲率半径のばらつきをいずれも0.03mm以内に収めることができ、より良好な形状精度が得られた。また、傾斜角度が上記の範囲よりも小さな実施例1と、上記の範囲よりも大きな実施例5と実施例6においては、ガラス基板の面取面と側壁面とのエッジの曲率半径のばらつきが若干大きくなった。
2.これに対し、ガラス基板を傾斜させないで研磨処理を行った比較例1では、ガラス基板の主表面と面取面とのエッジの曲率半径のばらつきについては問題はなかったが面取面側への加工が進行しにくいため、ガラス基板の面取面と側壁面とのエッジの曲率半径のばらつきが大きくなり良好な形状精度は得られなかった。これは、前にも説明したように、面取面と側壁面とで加工レートが異なり、所定の加工時間内では面取面と側壁面の両方を同じ品質の鏡面に仕上ることができなかったことによるものと考えられる。
また、上記実施例3において、プラス20度からマイナス20度の範囲を1往復2秒で連続的に変化させた(往復運動させた)ところ、面取面と側壁面との間のエッジの曲率半径のばらつきが「◎」の評価となった。
また、内径側について表1と同じ条件で実施したところ、同様の結果が得られた。
また、端面研磨処理の前に行う研削加工において、ガラス基板面に対して砥石を傾斜させずに研削加工を実施した(研磨取代は同じ)結果、端面の表面粗さRaの最大値が0.12μmとなり若干増加したものの、エッジ曲率半径のばらつきは同等であった。
上記実施例1の端面研磨工程において、本実施例Aでは、前述の図5に示す方法に従って磁性スラリを用いる研磨処理を行った。
図5に示すように、一対の磁石からなる磁気発生手段を内蔵した研磨装置を用いて、これら2つの磁石間に磁性スラリの塊を形成させた。そして、これら2つの磁石とガラス基板とを互いに回転させることにより、ガラス基板の端面を研磨した。両者の回転方向は図3に示すように互いに逆方向とした。
研磨処理を施すガラス基板の周囲に、上記構成の磁気発生手段の1台(磁気発生手段#1)を図5の(a)に示す位置に配置し、上記構成の磁気発生手段の別の1台(磁気発生手段#2)を図5の(b)に示す位置に配置し、上記構成の磁気発生手段のさらに別の1台(磁気発生手段#3)を図5の(b)に示す磁気発生手段(#2)に対して上下反転させ図5の(b)において下側の面取面に沿う磁力線を発するように配置した。
なお、端面研削工程及び端面研磨工程における、回転方向、砥石又は磁性スラリの塊の回転数、基板の回転、基板と砥石(又は磁性スラリの塊)の回転数の相対比、および磁石の磁束密度等については、上述の実施の形態中に記載の範囲である。
こうして、ガラス基板の外周端面の側壁面と面取面の研磨を同時に行った。加工後の基板の外周端面の表面粗さは、側壁面、面取面ともにRzで0.1μm以下であった。
また、ガラス基板の内周側については、従来の研磨ブラシを用いて研磨を行った。
以上のようにして、上記端面研磨を終えたガラス基板を洗浄した。
上記工程を経て得られたガラス基板の主表面の表面粗さを原子間力顕微鏡(AFM)にて測定したところ、Rz=1.53nm、Ra=0.13nmと超平滑な主表面を持つガラス基板を得た。
また、得られたガラス基板の外径は65mm、内径は20mm、板厚は0.635mmであった。
こうして、本実施例(実施例A)の磁気ディスク用ガラス基板を得た。
また、研磨処理を施すガラス基板の周囲に、上記構成の磁気発生手段の1台をガラス基板の一方の面取面と側壁面とを主に研磨する位置に配置し、上記構成の磁気発生手段の別の1台をガラス基板の他方の面取面と側壁面とを主に研磨する位置に配置して、当該ガラス基板の端面研磨を行ったこと以外は、上記実施例Aと同様にして磁気ディスク用ガラス基板を得た(実施例B)。
また、上記実施例に対する比較例(比較例A)として、1台の磁気発生手段を用いて、その磁力線の方向と直交する方向にガラス基板を挿入して当該ガラス基板の端面研磨を行った(図5(a)の状態と同様)こと以外は、上記実施例と同様にして磁気ディスク用ガラス基板を得た。なお、本比較例においては、ガラス基板端面の側壁面と面取面の表面粗さが同等になるまで時間を延長して研磨加工を行った。
なお、上記比較例において、研磨時間を実施例と同じ時間とした場合について試作を行ない、得られた磁気ディスク用ガラス基板の側壁面と面取面との粗さ(Rz)をそれぞれレーザー顕微鏡で計測し、面取面と側壁面との粗さ(Rz)の差を実施例と比較したところ、実施例の方が上記差が小さいことが確認された。
1.ガラス基板端面の面取面と側壁面の加工レートが同等になるように磁力線の向きが異なる3つの磁気発生手段を用いてガラス基板の端面を研磨処理した実施例Aにおいては、端面研磨処理後の、ガラス基板の面取面と側壁面とのエッジの曲率半径のばらつきと、ガラス基板の主表面と面取面とのエッジの曲率半径のばらつきをいずれも0.03mm以内に収めることができ良好な形状精度が得られた。また、2つの磁気発生手段を用いた実施例Bについても実施例Aと同様な結果が得られた。
2.これに対し、1つの磁気発生手段を図5(a)の状態に配置してガラス基板の端面研磨を行った比較例Aでは、ガラス基板の面取面と側壁面とのエッジの曲率半径のばらつきと、ガラス基板の主表面と面取面とのエッジの曲率半径のばらつきのいずれもが大きくなり良好な形状精度は得られなかった。これは、前にも説明したように、面取面と側壁面とで加工レートが異なり、面取面と側壁面の両方を同じ品質に仕上るまで加工を行ったために形状精度が劣化してしまったものと考えられる。
上記実施例3で得られた磁気ディスク用ガラス基板に以下の成膜工程を施して、垂直磁気記録用磁気ディスクを得た。
すなわち、上記ガラス基板上に、Ti系合金薄膜からなる付着層、CoTaZr合金薄膜からなる軟磁性層、Ru薄膜からなる下地層、CoCrPt合金からなる垂直磁気記録層、カーボン保護層、潤滑層を順次成膜した。保護層は、磁気記録層が磁気ヘッドとの接触によって劣化することを防止するためのもので、水素化カーボンからなり、耐磨耗性が得られる。また、潤滑層は、アルコール変性パーフルオロポリエーテルの液体潤滑剤をディップ法により形成した。
得られた磁気ディスクについて、DFHヘッドを備えたHDDに組み込み、80℃かつ80%RHの高温高湿環境下においてDFH機能を作動させつつ1ヶ月間のロードアンロード耐久性試験を行ったところ、特にフラッタリングやコロージョンに起因する障害も無く、良好な結果が得られた。
10 円盤状ガラス基板(ガラスディスク)
11 ガラス基板の主表面
12 ガラス基板の外周側端面
12a 側壁面
12b 面取面
20 端面研磨装置
21,22 磁石
23 スペーサ
24 外装部材
25 磁力線
26 磁性スラリの塊
Claims (11)
- 主表面を有する円盤状のガラス基板の端面を加工する端面加工処理を含む磁気ディスク用ガラス基板の製造方法であって、
前記端面加工処理は、
対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、
前記磁力線の方向と直交する面方向に対して前記ガラス基板の主表面を傾斜させた状態で前記ガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を同時に研磨する端面研磨処理を含むことを特徴とする磁気ディスク用ガラス基板の製造方法。 - 前記ガラス基板の傾斜角度は、10度~45度の範囲内であることを特徴とする請求項1に記載の磁気ディスク用ガラス基板の製造方法。
- 加工の途中で前記ガラス基板の傾斜角度を変化させることを特徴とする請求項1又は2に記載の磁気ディスク用ガラス基板の製造方法。
- 前記ガラス基板の加工部を中心にして前記ガラス基板の傾斜角度を連続的又は段階的に変化させることを特徴とする請求項1又は2に記載の磁気ディスク用ガラス基板の製造方法。
- 円盤状のガラス基板の端面を加工する端面加工処理を含む磁気ディスク用ガラス基板の製造方法であって、
前記端面加工処理は、対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、前記ガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理を含み、
前記ガラス基板の側壁面を主に研磨する第1の磁気発生手段と、前記ガラス基板の面取面を主に研磨する第2の磁気発生手段を用い、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されることを特徴とする磁気ディスク用ガラス基板の製造方法。 - 円盤状のガラス基板の端面を加工する端面加工処理を含む磁気ディスク用ガラス基板の製造方法であって、
前記端面加工処理は、対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、前記ガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理を含み、
前記ガラス基板の一方の面取面と側壁面とを主に研磨する第1の磁気発生手段と、前記ガラス基板の他方の面取面と側壁面とを主に研磨する第2の磁気発生手段とを用い、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されることを特徴とする磁気ディスク用ガラス基板の製造方法。 - 前記第2の磁気発生手段は、前記ガラス基板の一方の主表面と側壁面との間の面取面を主に研磨する磁気発生手段と、他方の主表面と側壁面との間の面取面を主に研磨する磁気発生手段とを備え、各々の磁力線の向きが異なるように配置されることを特徴とする請求項5に記載の磁気ディスク用ガラス基板の製造方法。
- 前記端面研磨処理の前に、前記ガラス基板の端面に面取面と側壁面の両方の面を形成する研削処理を行い、該研削処理は、前記ガラス基板の主表面と直交する軸に対して研削砥石の回転軸を傾斜させた状態で当該研削砥石を前記ガラス基板の端面に当接させて当該ガラス基板の端面を研削する研削処理を含むことを特徴とする請求項1乃至7のいずれかに記載の磁気ディスク用ガラス基板の製造方法。
- 請求項1乃至8のいずれかに記載の磁気ディスク用ガラス基板の製造方法により製造された磁気ディスク用ガラス基板上に、少なくとも磁気記録層を形成することを特徴とする磁気ディスクの製造方法。
- 対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、円盤状のガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理に使用する磁気ディスク用ガラス基板の端面研磨装置であって、
前記ガラス基板の側壁面を主に研磨する第1の磁気発生手段と、前記ガラス基板の面取面を主に研磨する第2の磁気発生手段とを備え、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されていることを特徴とする磁気ディスク用ガラス基板の端面研磨装置。 - 対向配置された一対の磁石からなる磁気発生手段を用いて磁力線を形成させ、磁性粒子と研磨砥粒を含む磁性スラリを前記磁力線に保持させることにより、前記磁力線に沿って前記磁性スラリの塊を形成させ、円盤状のガラス基板の端面を前記磁性スラリの塊と接触させて、前記ガラス基板の端面の側壁面と、該ガラス基板の主表面と前記側壁面との間の少なくとも一方の面取面との両方の面を研磨する端面研磨処理に使用する磁気ディスク用ガラス基板の端面研磨装置であって、
前記ガラス基板の一方の面取面と側壁面とを主に研磨する第1の磁気発生手段と、前記ガラス基板の他方の面取面と側壁面とを主に研磨する第2の磁気発生手段とを備え、前記第1の磁気発生手段と前記第2の磁気発生手段は各々の磁力線の向きが異なるように配置されていることを特徴とする磁気ディスク用ガラス基板の端面研磨装置。
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SG11201508855QA SG11201508855QA (en) | 2013-04-30 | 2014-04-30 | Method for manufacturing magnetic-disk glass substrate, method for manufacturing magnetic disk, and device for polishing edge surface of magnetic-disk glass substrate |
CN201480024064.3A CN105164752B (zh) | 2013-04-30 | 2014-04-30 | 磁盘用玻璃基板的制造方法和磁盘的制造方法、以及磁盘用玻璃基板的端面研磨装置 |
JP2015514872A JP6156967B2 (ja) | 2013-04-30 | 2014-04-30 | ガラス基板の製造方法及び磁気ディスクの製造方法、並びにガラス基板の端面研磨装置 |
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CN110751961B (zh) * | 2015-12-28 | 2021-10-26 | Hoya株式会社 | 圆环状的玻璃坯板及制造方法、圆环状的玻璃基板的制造方法和磁盘用玻璃基板的制造方法 |
JP6695318B2 (ja) * | 2017-12-27 | 2020-05-20 | Hoya株式会社 | 円盤状ガラス基板の製造方法、薄板ガラス基板の製造方法、導光板の製造方法及び円盤状ガラス基板 |
CN111037370B (zh) * | 2019-11-29 | 2021-04-27 | 上海磐盟电子材料有限公司 | 一种圆晶倒角工艺 |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61265261A (ja) * | 1985-05-17 | 1986-11-25 | Fuji Electric Co Ltd | 内面磁気研磨加工方法 |
JPS6239172A (ja) * | 1985-08-09 | 1987-02-20 | Kureha Chem Ind Co Ltd | 磁気研磨装置 |
JPH1119863A (ja) * | 1997-06-27 | 1999-01-26 | Kyoei Denko Kk | 磁力線ビーム加工用研磨材 |
JP2005050501A (ja) * | 2003-07-15 | 2005-02-24 | Hoya Corp | 磁気ディスク用基板の製造方法、磁気ディスク用基板の製造装置及び磁気ディスクの製造方法 |
JP2006095643A (ja) * | 2004-09-29 | 2006-04-13 | Toshiba Corp | 磁気研磨装置及び磁気研磨方法 |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2005005099A1 (ja) * | 2003-07-15 | 2005-01-20 | Hoya Corporation | 磁気ディスク用基板の製造方法、磁気ディスク用基板の製造装置及び磁気ディスクの製造方法 |
JP5029777B1 (ja) * | 2011-11-22 | 2012-09-19 | 旭硝子株式会社 | 磁気記録媒体用ガラス基板、および該磁気記録媒体用ガラス基板を用いた磁気記録媒体 |
-
2014
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- 2014-04-30 SG SG11201508855QA patent/SG11201508855QA/en unknown
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- 2014-04-30 MY MYPI2015703832A patent/MY182141A/en unknown
- 2014-04-30 WO PCT/JP2014/062031 patent/WO2014178417A1/ja active Application Filing
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61265261A (ja) * | 1985-05-17 | 1986-11-25 | Fuji Electric Co Ltd | 内面磁気研磨加工方法 |
JPS6239172A (ja) * | 1985-08-09 | 1987-02-20 | Kureha Chem Ind Co Ltd | 磁気研磨装置 |
JPH1119863A (ja) * | 1997-06-27 | 1999-01-26 | Kyoei Denko Kk | 磁力線ビーム加工用研磨材 |
JP2005050501A (ja) * | 2003-07-15 | 2005-02-24 | Hoya Corp | 磁気ディスク用基板の製造方法、磁気ディスク用基板の製造装置及び磁気ディスクの製造方法 |
JP2006095643A (ja) * | 2004-09-29 | 2006-04-13 | Toshiba Corp | 磁気研磨装置及び磁気研磨方法 |
Non-Patent Citations (1)
Title |
---|
HITOSHI NISHIDA ET AL.: "Jiki Kinosei Ryutai o Mochiita Kan Naimen Micro Kako Gijutsu no Genri to Tokusei", DAI 23 KAI 'DENJIRYOKU KANREN NO DYNAMICS' SYMPOSIUM KOEN RONBUNSHU, 18 May 2010 (2010-05-18), pages 519 - 522 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2017104926A (ja) * | 2015-12-08 | 2017-06-15 | 国立大学法人宇都宮大学 | 磁気研磨装置及び磁気研磨方法 |
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CN105164752B (zh) | 2018-09-14 |
JPWO2014178417A1 (ja) | 2017-02-23 |
JP6156967B2 (ja) | 2017-07-05 |
MY182141A (en) | 2021-01-18 |
CN105164752A (zh) | 2015-12-16 |
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