WO2014104377A1 - Procédé de fabrication de substrats en verre pour disques magnétiques et procédé de fabrication de disques magnétiques - Google Patents

Procédé de fabrication de substrats en verre pour disques magnétiques et procédé de fabrication de disques magnétiques Download PDF

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Publication number
WO2014104377A1
WO2014104377A1 PCT/JP2013/085292 JP2013085292W WO2014104377A1 WO 2014104377 A1 WO2014104377 A1 WO 2014104377A1 JP 2013085292 W JP2013085292 W JP 2013085292W WO 2014104377 A1 WO2014104377 A1 WO 2014104377A1
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Prior art keywords
glass substrate
magnetic
processing
grinding
face
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PCT/JP2013/085292
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English (en)
Japanese (ja)
Inventor
武良 高橋
政明 植田
修平 東
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Hoya株式会社
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Application filed by Hoya株式会社 filed Critical Hoya株式会社
Priority to CN201380061388.XA priority Critical patent/CN104813396A/zh
Priority to SG11201505032QA priority patent/SG11201505032QA/en
Priority to JP2014554628A priority patent/JPWO2014104377A1/ja
Publication of WO2014104377A1 publication Critical patent/WO2014104377A1/fr

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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
    • 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

Definitions

  • the present invention relates to a method for manufacturing a glass substrate for a magnetic disk mounted on a magnetic disk device such as a hard disk drive (HDD) and a method for manufacturing a magnetic disk.
  • a magnetic disk device such as a hard disk drive (HDD)
  • HDD hard disk drive
  • a magnetic disk as one of information recording media mounted on a magnetic disk device such as a hard disk drive (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 manufactured by sequentially performing steps such as shape processing (end grinding and chamfering), end surface polishing, main surface grinding, main surface polishing, and chemical strengthening on a disk-shaped glass substrate. .
  • shape processing end grinding and chamfering
  • end surface polishing main surface grinding
  • main surface polishing main surface polishing
  • chemical strengthening on a disk-shaped glass substrate.
  • 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.
  • OD edge damage occurs when the side wall surface of the substrate comes into contact with the carrier during the polishing process of the main surface.
  • the variation in edge angle is large, or the inclination of the side wall surface is perpendicular to the main surface. If it is not present or if the length is short, it has been found that it is likely to occur due to strong local contact with the carrier.
  • the pressure applied to the back side of the chamfered surface (near the main surface) and the side wall surface varies depending on the way the bristle material of the brush is bent. There is a problem that the angle of the edge between the side wall surface and the side wall surface is easily disturbed. Further, the brush end face polishing has a problem that although the end face can be mirror-finished, a linear polishing streak tends to remain.
  • the apparatus is arranged in terms of the arrangement of magnets and the like.
  • the structure is complicated, the distance between the magnet and the magnetic particles is long, and the slurry cannot be sufficiently held, so that the processing rate is low. Further, this method has a problem that the outer peripheral side end face of the substrate cannot be polished.
  • the present invention is particularly suitable for the end face of a magnetic disk glass substrate from the viewpoint of meeting the demand for higher recording density of a magnetic disk, which is urgently required to ensure reliability for higher recording density. It is an object of the present invention to provide a method for producing a glass substrate for a magnetic disk that enables stable processing that can be finished in 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 glass substrate, wherein the end surface processing includes forming a line of magnetic force using magnetism generating means, and including a magnetic material and a polishing abrasive.
  • a first process of forming the magnetic slurry lump by holding the slurry at the magnetic field lines, and processing the end surface of the glass substrate in contact with the magnetic slurry lump, before the first process;
  • the groove shape is formed so that both of the side wall surface of the end surface of the glass substrate and the chamfered surface between the main surface of the glass substrate and the side wall surface can be processed simultaneously.
  • a second process of processing the glass substrate in a state in which the glass substrate is inclined with respect to the groove direction of the groove formed on the grindstone.
  • (Configuration 2) The method for manufacturing a glass substrate for a magnetic disk according to Configuration 1, wherein a process of forming a chamfered surface on an end surface of the glass substrate is performed before the second process.
  • (Configuration 3) The method for producing a glass substrate for a magnetic disk according to Configuration 2, wherein the chamfered surface forming process and the second process are performed at different angles in the groove direction of the grindstone with respect to the substrate.
  • (Configuration 4) 4. The method of manufacturing a glass substrate for a magnetic disk according to claim 1, wherein the surface roughness of the end surface of the glass substrate after the end surface processing is 0.2 ⁇ m or less in terms of Rmax.
  • (Configuration 5) The method for manufacturing a glass substrate for a magnetic disk according to any one of the constitutions 1 to 4, wherein a thickness of the glass substrate put into the end face processing is 0.5 mm or less.
  • (Configuration 6) The method of manufacturing a glass substrate for a magnetic disk according to any one of configurations 1 to 5, wherein the glass substrate is made of crystallized glass.
  • (Configuration 7) 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 6.
  • the present invention from the viewpoint of meeting the demand for higher recording density of magnetic disks, it is possible to ensure the dimensional shape accuracy of the end surface of the glass substrate for magnetic disks, the finished surface quality of chamfering processing, etc. Stable end surface processing that can be finished with a shape and high quality is possible, and a glass substrate for a magnetic disk having a substrate end surface finished with a high precision shape and high quality can be stably provided.
  • the end surface of the substrate is finished with high precision shape and high quality. It is possible to provide a magnetic disk that can prevent the occurrence of a failure due to the state, can achieve higher recording density, and has high reliability.
  • FIG. 1 shows a glass substrate for a magnetic disk according to the present invention, in which (A) is a side view showing a part of the glass substrate and (B) is a plan view thereof.
  • the embodiment of the 2nd processing of the present invention is shown, (A) is a sectional side view showing the state where the peripheral side end face of the glass substrate for magnetic disks is processed using a grindstone, (B) is the plane It is a figure (partial plane sectional view).
  • (A) is a sectional side view showing a state in which the inner peripheral side end face of the magnetic disk glass substrate is processed using a grindstone, and (B) is a plan sectional view of the grindstone.
  • (A)-(c) is a figure for demonstrating the 1st process of this invention, respectively. It is a perspective view in the state where the 1st processing of the present invention is performed. It is sectional drawing which shows the end surface shape of the glass substrate for magnetic discs.
  • a glass substrate for a magnetic disk is usually manufactured through a substrate preparation step, a shape processing step, an end surface polishing step, a main surface grinding step, a main surface polishing step, a chemical strengthening step, and the like.
  • the method for manufacturing a glass substrate for a magnetic disk according to the present invention includes an end face processing for processing the end face of the glass substrate.
  • the end face processing includes the following first process and a second process performed as a pre-process of the first process.
  • the first treatment forms magnetic lines of force using magnetism generating means, forms a mass of the magnetic slurry by holding the magnetic slurry containing the magnetic material and abrasive grains to the magnetic lines of force, and forms the end face of the glass substrate. It is a process processed in the state contacted with the said magnetic slurry lump.
  • the second treatment is performed before the first treatment, and both the side wall surface of the end surface of the glass substrate and the chamfered surface between the main surface of the glass substrate and the side wall surface. This is a process in which a grindstone having a groove shape formed so that the surface can be processed at the same time is used, and the glass substrate is processed in an inclined state with respect to the groove direction of the groove shape formed on the grindstone.
  • the second process may be referred to as “inclined grinding process” or “inclined grinding process”.
  • the first processing may be referred to as “MRF processing” or “MRF processing”.
  • MRF is an abbreviation for magnetorheological fluid.
  • the shape processing (end face grinding and chamfering) step and the end face polishing step are performed by an end face processing process including the first process and a second process performed as a pre-process of the first process. It can be performed.
  • a shape processing step is performed by grinding using a general-purpose grindstone, and then an end surface polishing step is performed by brush polishing.
  • the end face processing referred to in the present invention is a process for chamfering the end face of the substrate and creating a desired end face shape including the chamfered face and the side wall face (a process for obtaining shape accuracy).
  • the shape processing step is performed by inclined grinding (second processing) as the pre-processing of the first processing, and then by MRF processing (first processing).
  • the end surface polishing step is performed.
  • variation in the finishing angle of the edge (see A part in FIG. 6) between the chamfered surface 12b and the side wall surface 12a particularly on the end surface of the glass substrate 1 is small, and lines such as polishing streaks are present. It is possible to finish with high quality end face.
  • MRF processing enables high-quality polishing.
  • pretreatment is the conventional general grindstone processing (the substrate is not inclined with respect to the groove direction of the grindstone)
  • the roughness of the grinding surface is low. Since it is high, the machining allowance is increased for low roughness in MRF processing (about 50 ⁇ m, which is the same as that of conventional brush polishing), and the deviation from the shape made with a general-purpose grindstone becomes large. I'll be overwhelmed.
  • the substrate end surface is finished in a quasi-mirror surface state that is difficult to realize by the conventional general grinding wheel processing (the substrate is not inclined with respect to the groove direction of the grinding stone), the rounded edges Deterioration of shape accuracy can be prevented and mass productivity can be improved.
  • the end surface processing of the present invention it is possible to finish the substrate end surface in a quasi-mirror surface state before MRF processing. Note that in the conventional grindstone processing in which the conventional substrate is not tilted with respect to the groove direction of the grindstone, the trajectory of the grinding stone that comes into contact with the end face is constant, so that the substrate is easily damaged.
  • the machining allowance on the side wall surface of the substrate end surface by the above-described inclined grinding is about 10 to 1000 ⁇ m.
  • the roughness of the processed surface after the inclined grinding is preferably 1.5 ⁇ m or less at Rmax, and the roughness of the processed surface after the MRF processing is preferably 0.5 ⁇ m or less at Rmax.
  • Rmax is calculated according to JIS B0601: 1982.
  • the roughness measurement conditions in the present invention are as follows. Measuring device: Laser microscope Measurement area: 50 ⁇ m ⁇ 50 ⁇ m
  • the end surface processing in this invention is carrying out the process which chamfers the end surface of a glass substrate using grindstones, such as a total shape, before the said inclination grinding process. That is, the shape processing step is performed by chamfering the end surface using a grindstone such as a general shape and the subsequent inclined grinding processing, and then the end surface polishing step is performed by the MRF processing.
  • the burden of the inclined grinding process can be reduced, and even smaller abrasive grains can be used in the inclined grinding process. Therefore, the substrate end surface can be more easily made into a quasi-mirror surface, and the machining allowance for the subsequent MRF process is increased. Can be reduced.
  • the finished shape accuracy can be further increased. Specifically, in addition to the small variation in the finishing angle of the edge between the chamfered surface 12b and the side wall surface 12a on the end surface of the glass substrate 1 described above (see part A in FIG. 6), Variations in the finished angle of the edge between the surface 11 and the chamfered surface 12b (see section B in FIG. 6) are reduced, and there are no streaks such as polishing streaks (microscopic observation). is there. In addition, when performing a general-type grindstone process before an inclination grinding process, it is preferable to carry out so that a board
  • substrate may not be inclined with respect to the groove direction of a grindstone.
  • it may be performed by inclining at an angle different from the inclination angle at the time of the inclined grinding by 2 degrees or more.
  • the angle of the trajectory of the grindstone in the general grindstone processing and the slant grinding processing is different, so that the streak due to the two processes cancels out, the end face quality is further improved, and the production efficiency is improved.
  • the difference in inclination is smaller than 2 degrees, the above-described canceling effect is reduced, and the quality of the end face may not be improved.
  • you may change the angle of inclination substantially by reversing the rotation direction of a board
  • the roughness of the processed surface after the inclined grinding is preferably about 1.5 ⁇ m or less in terms of Rmax, and the roughness of the processed surface after the MRF processing is about 0.5 ⁇ m or less in terms of Rmax. It is preferable that In addition, a publicly known method can be used for the total-type grindstone processing in which the substrate is not inclined with respect to the groove direction of the grindstone. It is preferable to use a grindstone containing diamond abrasive grains of # 100 to # 1000.
  • the present invention is not limited to the above-described embodiment.
  • the above-described inclined grinding process can be applied to the end face polishing process by changing the machining condition from that during grinding.
  • FIG. 1 is an overall view of a glass substrate 1 for a magnetic disk to which the present invention is applied, in which (A) is a side view showing a part of the glass substrate in cross section, and (B) is a plan view thereof.
  • the glass substrate 1 is formed in a disc (disk) shape as a whole with a circular hole in the center, and has a front and back main surfaces 11, an outer peripheral end surface 12 formed between the main surfaces 11, and an inner surface. And an end face 13 on the circumferential side.
  • the end surface 12 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 (chamfered surfaces) formed between the side wall surface 12a and the front and back main surfaces 11 respectively.
  • 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 the inner diameter of a circular hole in the center of the glass substrate 1.
  • the main surface 11, the outer peripheral side end surface 12, and the inner peripheral side end surface 13 of the magnetic disk glass substrate 1 are polished (mirror polished) so as to have a predetermined surface roughness.
  • Both the outer peripheral side end surface 12 and the inner peripheral side end surface 13 are finished to the end face shape as described above, and the surface roughness is finished to a mirror surface state with, for example, Rmax of 1 ⁇ m or less and Ra of 0.1 ⁇ m or less. Is usually required.
  • the glass substrate 1 for a magnetic disk is manufactured by sequentially performing each of the above steps on a glass substrate (glass disk) 10 formed into a predetermined disk shape by, for example, direct pressing.
  • the inclined grinding process (second process) performed as a pre-process of the above-described MRF process (first process) will be described in detail.
  • FIG. 2 shows an embodiment of the second process (inclined grinding) of the present invention, wherein (A) is a side showing a state in which the outer peripheral side end face of the magnetic disk glass substrate is processed using a grindstone.
  • Sectional view (B) is a plan view thereof (however, the grinding wheel is a plan sectional view taken along line II-II in FIG. (A)).
  • the second treatment is applied to the shape processing step, but can also be applied to the end surface polishing step.
  • the case where it applies mainly to a shape processing process is demonstrated.
  • the grinding wheel 2 used for grinding the outer peripheral side end face of the glass substrate 10 is formed in a cylindrical shape as a whole and has a groove 3 shape on the inner peripheral side thereof.
  • the groove 3 is formed so that both the side wall surface of the outer peripheral side end surface of the glass substrate 10 and the chamfered surface between the main surface and the side wall surface of the glass substrate can be ground simultaneously.
  • a groove shape including a side wall portion (side wall surface grinding portion) 3a and chamfer portions (chamfered surface grinding portions) 3b and 3b existing on both sides thereof is provided.
  • the side wall 3a and the chamfered portions 3b and 3b of the groove 3 are formed in a predetermined size and shape in consideration of the target size and shape of the ground surface of the glass substrate 10 to be finished.
  • the glass substrate 10 has an axis of rotation L 10 passing through the center O 10
  • the grinding wheel 2 has a rotary shaft L 2 passing through the center O 2
  • the grinding wheel 2 tilt state inner peripheral side inclines the glass substrate 10 relative to the grooves formed 3 groove direction shape of, i.e.
  • the glass substrate 10 is ground with a predetermined angle ⁇ , for example, with respect to the groove direction of the groove 3 formed on the inner peripheral side of the grinding wheel 2, so that the end surface of the glass substrate 10 is abutted.
  • the trajectory of the grinding wheel 2 in contact with the grinding wheel 2 is not constant, and the convex portion (abrasive grains) of the grinding wheel 2 abuts and acts on the substrate end surface at random positions. Can be finished with higher smoothness.
  • the vector of the grinding resistance to the abrasive grains, which are cutting edges, is dispersed, damage can be reduced while maintaining the sharpness, so that there is also an effect of improving the life of the grindstone.
  • the inclination angle ⁇ of the glass substrate 10 with respect to the groove direction on the inner peripheral side of the grinding wheel 2 can be arbitrarily set. However, in order to achieve the above-described effects more effectively, for example, in the range of 2 to 15 degrees. It is preferable to be inside. More preferably, it is 10 degrees or less.
  • the size of the cylinder of the grinding wheel 2 is What is necessary is just to determine suitably considering the outer diameter of a glass substrate, for example.
  • the outer peripheral side end surface 12 of the glass substrate 10 is brought into contact with the inner peripheral side of the grinding wheel 2 and the glass substrate 10 and the grinding wheel 2 are relatively moved, whereby the glass substrate end surface is ground.
  • it is advantageous to perform grinding by bringing the outer peripheral side end face 12 of the glass substrate 10 into contact with the inner peripheral side of the grinding wheel 2 and rotating both the glass substrate 10 and the grinding wheel 2. It is.
  • the peripheral speeds (tangential speeds) at the processing points of the grinding wheel 2 and the glass substrate 10 do not have to be particularly limited, but from the viewpoint of grindability and processing efficiency, for example, the peripheral speed of the grinding wheel 2 (A) is preferably 1000 to 3000 m / min, and the peripheral speed (B) of the glass substrate 10 is preferably about 5 to 30 m / min. Accordingly, it is preferable in the present invention that the peripheral speed ratio A / B between the grinding wheel 2 and the glass substrate 10 is 80 or more, preferably in the range of 100 to 300.
  • the rotating direction of the grinding wheel 2 and the glass substrate 10 may be either a down cut or an up cut.
  • a resin grindstone made of abrasive grains and resin can be used.
  • a resin grindstone containing diamond abrasive grains as a grindstone.
  • a metal grindstone composed of abrasive grains and a metal binder, a vitrified grindstone composed of abrasive grains and a vitreous binder, and a composite grindstone obtained by mixing these binders can also be used.
  • abrasive grains are added to a suitable filler as necessary, and bonded to a phenol resin, an epoxy resin, a polyethylene resin, a polystyrene resin, a polyimide resin, or the like, and formed into a predetermined shape. Things can be used. Also, alumina abrasive grains, cubic boron nitride abrasive grains, and the like can be used. As the grain size of the abrasive grains, for example, # 2000 to # 3000 or finer abrasive grains can be suitably used.
  • diamond abrasive grains are bonded with resin bonds to form a grindstone during inclined grinding, and it is particularly important to control the bond strength between the abrasive grains and the resin. found. It has been found that this bond strength has a strong influence on grindability (workability) and surface quality during inclined grinding.
  • the index is expressed as “grinding wheel elastic modulus”.
  • a preferable range of the grindstone elastic modulus is 1500 to 3500 [N / mm]. This parameter is a spring constant, and if it is high, the grindability is good and the dimensional accuracy is improved, but scratches are easily generated. On the other hand, if it is low, the surface quality is improved, but the grinding rate is lowered.
  • this grindstone elastic modulus can be evaluated at a load of 15 kgf using a bending strength measuring tester using an HRF indenter.
  • 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.
  • a groove is formed inside a cylindrical grindstone and coolant is supplied thereto, the retention of the coolant is enhanced, and clogging or clogging of the grindstone can be made difficult to occur. .
  • the inclined grinding process to the mirror polishing process of the end face.
  • it is performed by the same method as the grinding process except that the elastic modulus of the resin bond grindstone, the type of the grindstone and the grinding liquid, and the peripheral speed ratio of the grindstone and the glass substrate are changed from those during the grinding process. be able to.
  • the grindstone elastic modulus of the resin bond grindstone is changed, the mirror surface quality is improved when it is 1500 to 2500 [N / mm]. Therefore, it is suitable when the substrate end surface is mirror-polished by inclined grinding. Further, if it is 2500 to 3500 [N / mm], the shape accuracy and grindability are improved, and therefore, it is suitable for grinding by inclined grinding.
  • FIG. 3A is a side sectional view showing a state where the inner peripheral side end face of the glass substrate for magnetic disk is ground using a grinding wheel
  • FIG. 3B is a plan sectional view of the grinding wheel ((A ) Is a plan sectional view taken along line III-III in FIG.
  • the grinding wheel 4 used for grinding the inner peripheral side end face of the glass substrate 10 has a groove 5 shape.
  • the groove 5 is formed so that both the side wall surface of the inner peripheral side end surface of the glass substrate 10 and the chamfered surface between the main surface and the side wall surface of the glass substrate can be ground simultaneously.
  • it has a groove shape including a side wall portion (side wall surface grinding portion) 5a and chamfer portions (chamfered surface grinding portions) 5b, 5b existing on both sides thereof.
  • the glass substrate 10 is inclined with respect to the groove direction of the groove 5 formed in the grinding wheel 4, that is, the rotation of the glass substrate 10 with respect to the rotation axis L 4 of the grinding wheel 4.
  • the grinding wheel 4 is brought into contact with the inner peripheral side end face 13 of the glass substrate 10, and both the glass substrate 10 and the grinding wheel 4 are rotated for grinding.
  • the outer peripheral side end surface of the glass substrate is obtained by grinding the inner peripheral side end surface while the glass substrate 10 is inclined, for example, by a predetermined angle ⁇ with respect to the groove direction of the groove 5 shape of the grinding wheel 4.
  • a predetermined angle ⁇ with respect to the groove direction of the groove 5 shape of the grinding wheel 4.
  • the inclination angle ⁇ of the glass substrate 10 with respect to the groove direction of the grinding wheel 4 can be arbitrarily set, in order to better exhibit the above-described effects, as in the case of grinding of the outer peripheral side end face.
  • a range of 2 to 15 degrees is preferable. More preferably, it is 10 degrees or less.
  • the peripheral speed and the peripheral speed ratio of each of the grinding wheel 4 and the glass substrate 10 may be appropriately set so as to be suitable for the grinding of the inner peripheral side end face.
  • FIGS. 4A to 4C are diagrams for explaining the first processing (MRF processing) of the present invention
  • FIG. 5 is a perspective view of the first processing of the present invention. It is.
  • the apparatus 20 used for MRF processing in the present invention polishes the end face of a glass substrate using a magnetism generating means and a magnetic slurry. 4 (a) to 4 (c) and FIG. 5 show a case where the outer peripheral side end face of the glass substrate is polished. The outline of the apparatus 20 will be described. As shown in FIG.
  • 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.
  • the end of the glass substrate can be inserted between the magnets 21 and 22 for processing. In this case, the exterior member 24 is not provided.
  • the glass substrate 10 that has been subjected to the inclined grinding process is held in a horizontal state by a holder (not shown).
  • the glass substrate 10 held by the holder is brought close to the exterior member 24, and a lump 26 (see FIGS. 4C and 5) described later and the outer peripheral side end surface of the glass substrate 10 are brought into contact with each other.
  • a holder (not shown) that holds the exterior member 24 and the glass substrate 10 of the apparatus 20 is connected to a drive motor (not shown).
  • the outer peripheral end surface of the glass substrate 10 can be polished by rotating the exterior member 24 and the holder to relatively move the outer peripheral end surface of the glass substrate 10 and the magnetic slurry lump 26.
  • the rotation directions of the exterior member 24 and the holder for holding the glass substrate 10 are rotated in opposite directions (see FIG. 5), and the relative speed of the peripheral speed between the exterior member 24 and the glass substrate 10 is set to 40 to 100 m / It is preferable to rotate as minutes. If the outer peripheral side end face of the glass substrate 10 and the magnetic slurry lump 26 can be relatively moved, either the glass substrate 10 or the magnetic slurry lump 26 may be fixed and the other may be rotated. In addition, both may be rotated in the same direction.
  • the pair of magnets 21 and 22 are close to each other and function as magnetism generating means to form a magnetic force line 25 as shown in FIG.
  • the lines of magnetic force 25 proceed so as to protrude outward from the centers of the magnets 21 and 22 and proceed in the thickness direction of the glass substrate 10.
  • 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.
  • the separation distance between the N pole end face of the magnet 21 and the S pole end face of the magnet 22 is set to a predetermined distance by causing the magnetic field lines 25 to protrude outward as shown in FIG. This is because a magnetic slurry lump 26 as shown in FIG.
  • 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.
  • 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.
  • an electromagnet may be used.
  • the spacer 23 is used in order to ensure a certain 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, but the outer member 24 is not used without using the spacer 23.
  • the magnets 21 and 22 are fixed, 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.
  • polishing the inner peripheral side of a glass substrate when grind
  • the polishing conditions may be the same as those on the outer peripheral side.
  • a magnetic material is held by magnetic lines of force, and a glass substrate is pressed against the magnetic material to process the substrate surface with the magnetic material.
  • the polishing rate and the polishing quality can be improved by the abrasive grains adhering to the magnetic material.
  • the magnetic material for example, a magnetic fluid containing magnetic fine particles or the like, or a magnetorheological fluid can be used.
  • Nonpolar oil or polar oil containing 3 to 5 g / cm 3 of magnetic fine particles containing an Fe (iron) component having a particle size of 0.1 to 10 ⁇ m, and surface activity A fluid containing an agent is used.
  • Nonpolar oil or polar oil has a viscosity of 100 to 1000 (mPa ⁇ sec) at room temperature (20 ° C.), for example.
  • the lump 26 formed by the magnetic slurry preferably includes abrasive grains as well as the magnetic particles when the magnetorheological fluid containing the magnetic fine particles is formed as a lump on the lines of magnetic force. Since the abrasive grains in the magnetorheological fluid are pushed out to a portion having a low magnetic force gradient due to the magnetic levitation effect, the abrasive grains are present in the vicinity of the end face of the glass substrate to be polished. And since it becomes a lump which has a comparatively high elastic characteristic with a magnetic force line, it can grind
  • abrasive grains contained in the magnetic slurry known abrasive grains of a glass substrate such as cerium oxide, colloidal silica, zirconia oxide, alumina abrasive grains, diamond abrasive grains and the like 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 contained, for example, in an amount of 3 to 15% by volume in the magnetic slurry.
  • the viscosity of the magnetic slurry is 1000 to 2000 [mPa ⁇ sec] at room temperature (20 ° C.) by adjusting the concentration of the magnetorheological fluid. This is because the magnetic slurry lump 26 is formed and the end face polishing is performed efficiently. preferable. If the viscosity is low (the concentration of the magnetorheological fluid is low), it is difficult to form the mass 26, and it may be difficult to polish by moving relative to the glass substrate 10 while being pressed against the end face.
  • the magnetic flux density in the magnetism generating means is preferably 0.3 to 0.8 [Tesla] from the viewpoint of forming the magnetic slurry lump 26 and performing the end face polishing efficiently.
  • the yield stress of the magnetic slurry containing the magnetorheological fluid and the abrasive grains is preferably 30 kPa or more, more preferably 30 to 60 kPa, when a magnetic field of 0.4 [Tesla] is applied.
  • the yield stress (yield shear stress) of the magnetorheological fluid can be obtained by, for example, the following method.
  • a device incorporating magnetic field application means permanent magnet, electromagnet, etc.
  • the yield stress of the magnetorheological fluid can be obtained by approximating the relationship between the obtained shear rate 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.
  • processing can be performed with uniform pressure from the back side of the chamfered surface of the substrate end surface to the side wall surface, which is difficult to process by conventional brush end surface polishing. It is possible to mirror the end shape without disturbing it.
  • the amount of bending (bending) of the bristle material changes depending on the location where it comes into contact with the substrate, so that it cannot be processed with uniform pressure.
  • the pressure changes with time because the hair material is bent or curved as the number of processing increases. For this reason, the variation in the shape of the end face tends to increase during mass production.
  • MRF processing since magnetic lines of force are used instead of brushes, processing can be performed with uniform pressure from the back side of the chamfered surface to the side wall surface. In addition, the pressure does not change over time.
  • the machining allowance by MRF machining is, for example, 50 ⁇ m or less, and preferably about 1 to 7 ⁇ m. Further, if the thickness is 5 ⁇ m or less, the shape accuracy is further improved, which is further preferable.
  • the end surface processing that combines the first processing (MRF processing) described above and the second processing (inclined grinding processing) performed as a pre-processing of the first processing, It is possible to achieve a high-precision shape and a high-quality surface of the substrate end face than the above method.
  • the end surface processing combined with the first processing and the second processing in the present invention is a thick plate (for example, 0.635 mm or more) even if the thickness of the glass substrate put into the end surface processing is, for example, 0.5 mm or less.
  • the end face quality equivalent to (1) can be ensured, which is particularly suitable for end face processing of a thin plate.
  • 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.
  • the present invention is particularly suitable for end face processing of a glass substrate made of crystallized glass.
  • the glass substrate is ground on the main surface for improving the dimensional accuracy and the shape accuracy.
  • This main surface grinding is usually performed by using a double-sided grinding device and grinding the main surface of the glass substrate using hard abrasive grains such as diamond. By grinding the main surface of the glass substrate in this way, a predetermined plate thickness and flatness are processed, and a predetermined surface roughness is obtained.
  • mirror polishing 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.
  • the main surface of the glass substrate after mirror polishing is preferably a mirror surface having an arithmetic average surface roughness Ra of 0.2 nm or less, more preferably 0.13 nm or less.
  • Ra and Rmax are roughnesses calculated in accordance with Japanese Industrial Standard (JIS) B0601.
  • the surface roughness (for example, the maximum roughness Rmax, the arithmetic average roughness Ra) is practically preferable to be the surface roughness obtained by measuring with an atomic force microscope (AFM). .
  • a chemical strengthening treatment after the first polishing process and before the second polishing process.
  • 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.
  • the chemically strengthened glass substrate is excellent in impact resistance, it is particularly preferable for mounting on a HDD for mobile use, for example.
  • 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 manufacturing 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.
  • Example 1 The following (1) substrate preparation step, (2) shape processing and end surface polishing step, (3) main surface grinding step, (4) main surface polishing step (first polishing step), (5) chemical strengthening step, (6 ) A glass substrate for a magnetic disk of this example was manufactured through a main surface polishing step (second polishing step).
  • a glass substrate (glass disk) made of disc-shaped aluminosilicate glass having a diameter of 66 mm ⁇ and a thickness of 1 mm was obtained from molten glass by direct pressing using an upper die, a lower die, and a barrel die.
  • 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 peripheral speed of the grindstone was 2000 m / min, and the peripheral speed of the glass substrate was 20 m / min (thus, the peripheral speed ratio between the grindstone and the glass substrate was 100).
  • the inclined grinding process was performed for about 30 seconds.
  • the surface roughness of the outer peripheral side end face of the glass substrate at this time was about 1.2 ⁇ m in Rmax for both the side wall face and the chamfered face. Further, the end surface on the inner peripheral side of the substrate was chamfered in the same manner as in the past using a predetermined total type grindstone.
  • the outer peripheral side end face of the glass substrate was polished.
  • the first treatment (MRF processing) of the present invention was applied to the outer peripheral end surface of the substrate in accordance with the method shown in FIGS.
  • a polishing apparatus having a cylindrical exterior member containing two magnets was used.
  • the dimensions of the built-in magnet were 216 mm in diameter and 60 mm in thickness.
  • a permanent magnet having a magnetic flux density of 6000 gauss was used.
  • these two magnets were fixed to the exterior member, and a predetermined separation distance was secured between the magnets.
  • the magnetic slurry is obtained by adding 5 ⁇ m of cerium oxide having an average particle diameter of 2 ⁇ m to a magnetorheological fluid in which fine particles of Fe (iron) having an average particle size of 2 ⁇ m are dispersed in nonpolar oil at a density of 3 g / cm 3. What was dispersed at a concentration of volume% was used. And magnetic slurry was supplied along the surface of an exterior member, and the lump of the magnetic slurry raised from the surface of the exterior member was formed. The rotational speed of the exterior member was appropriately adjusted in the range of 20 to 200 rpm, and the rotational speed of the glass substrate was 4000 rpm. The rotational directions of both were opposite to each other as shown in FIG. The processing time was about 3 minutes. Thus, the outer peripheral end face of the substrate was polished by MRF processing. The surface roughness of the outer peripheral end face of the substrate after processing was about 0.1 ⁇ m in Rmax for both the side wall face and the chamfered face.
  • the material of the bristle of the polishing brush was 6-6 nylon.
  • the rotational speed of this polishing brush was 1400 rpm, and the rotational speed of the glass substrate was 60 rpm in the direction opposite to that of the polishing brush.
  • cerium oxide was used as the polishing agent, and a polishing liquid at about 30 ° C. containing this cerium oxide was supplied. Thus, polishing was performed to an Rmax of about 0.5 ⁇ m. And the surface of the glass substrate which finished the said end surface grinding
  • the rotation speed of the surface plate was appropriately selected in the range of 10 to 100 rpm, and the load on the glass substrate was set to 100 g / cm 2 .
  • the sun gear and the internal gear of the lapping apparatus By rotating the sun gear and the internal gear of the lapping apparatus, both surfaces of the glass substrate housed in the carrier were simultaneously ground.
  • the glass substrate that had been subjected to the grinding process was immersed in each of the cleaning baths (applied with ultrasonic waves) of neutral detergent and water in order to perform ultrasonic cleaning.
  • a hard polisher (hard foamed urethane) was used as the polisher, and the first polishing step was performed.
  • the polishing liquid was water in which cerium oxide was dispersed as an abrasive, and the load was 100 g / cm 2 .
  • the glass substrate after the first polishing step was washed and dried.
  • Chemical strengthening step chemical strengthening was performed on the glass substrate after the cleaning.
  • a chemical strengthening solution prepared by mixing and melting potassium nitrate and sodium nitrate was prepared, and a glass substrate was immersed in the chemical strengthening solution to perform chemical strengthening treatment.
  • the second polishing step was performed by replacing the polisher with a polishing pad of soft polisher (suede).
  • the surface roughness of the glass substrate main surface is finished to a smooth mirror surface with a Ra of about 0.2 nm or less while maintaining the flat surface obtained in the first polishing step.
  • the polishing liquid was water in which colloidal silica was dispersed, and the load was 100 g / cm 2 .
  • the glass substrate after the second polishing step was washed and dried.
  • a glass substrate was obtained.
  • the main surface of the glass substrate was analyzed with an atomic force microscope (AFM) and an electron microscope, it was specular and surface defects such as protrusions and scratches were not observed.
  • the obtained glass substrate had an outer diameter of 65 mm, an inner diameter of 20 mm, and a plate thickness of 0.635 mm. Thus, a glass substrate for magnetic disk of this example was obtained.
  • Example 1 In the shape processing and end face polishing step of Example 1 above, only MRF processing was performed after the total grinding wheel processing. The conditions for MRF processing were the same as in Example 1. And the glass substrate for magnetic discs was obtained like Example 1 except this shape process and an end surface grinding
  • Example 2 In the shape processing and the end surface polishing step of Example 1 described above, only the inclined grinding processing was performed after the total grinding wheel processing. The conditions for the inclined grinding were the same as in Example 1. And the glass substrate for magnetic discs was obtained like Example 1 except this shape process and an end surface grinding
  • Example 3 In the shape processing and the end surface polishing step of Example 1 above, only conventional brush polishing was performed after the total grinding wheel processing.
  • the conditions for brush polishing were the same as the polishing conditions for the inner peripheral end face in Example 1.
  • the glass substrate for magnetic discs was obtained like Example 1 except this shape process and an end surface grinding
  • Example 4 In the shape processing and the end surface polishing step of Example 1, the slant grinding processing and the conventional brush polishing were performed after the total grinding wheel processing. The conditions for the slant grinding and brush polishing were the same as in Example 1. And the glass substrate for magnetic discs was obtained like Example 1 except this shape process and an end surface grinding
  • Example 1 in which the end face processing of the present invention in which inclined grinding is performed as pre-processing of MRF processing, the variation in the radius of curvature of the edge portion between the chamfered surface and the side wall surface of the substrate end surface after processing is different. It is small and has a well-finished surface state, and can achieve a high-precision shape and a high-quality surface. 2.
  • Comparative Example 1 in which only MRF processing was performed after the general grinding wheel processing and in Comparative Example 2 in which only inclined grinding processing was performed after the general grinding wheel processing, particularly in microscopic observation, polishing streaks and the like Streaks remained.
  • Comparative Example 3 (conventional example) in which brush grinding is performed after machining of the entire grindstone, since the machining allowance at the time of brush grinding is particularly uneven, the radius of curvature of the edge portion between the chamfered surface and the side wall surface The dispersion of Further, in the microscopic observation, streaks such as polishing streaks were observed. Furthermore, in Comparative Example 4 in which the inclined grinding and brush polishing were performed after the overall grinding wheel processing, the variation in the curvature radius of the edge portion between the chamfered surface and the side wall surface was slightly improved as compared with Comparative Example 3. In the microscopic observation, streaks such as polishing streaks were observed.
  • Example 2 In the shape processing and end surface polishing step of Example 1, the first general grinding wheel processing was omitted, and only the inclined grinding processing and MRF processing were performed.
  • the conditions of the slant grinding and MRF machining were the same as those in Example 1 except that the machining time was long so that a machining allowance during the slant grinding was sufficient.
  • the glass substrate for magnetic discs was obtained like Example 1 except this shape process and an end surface grinding
  • the curvature radius variation (Max-Min) of the edge portion was evaluated for the 100 glass substrates thus manufactured.
  • Example 2 In the same manner as in Example 1, it was evaluated by a contour shape measuring machine. The results are shown in Table 2, where ⁇ is a variation of 0.02 mm or less, and ⁇ is greater than 0.02 mm and 0.03 mm or less. Further, the same evaluation was performed on the glass substrate of Example 1 above, and the results are shown in Table 2.
  • the grindstone at the boundary between the main surface and the chamfered surface (the edge between the main surface and the chamfered surface) is particularly susceptible to damage. Therefore, it is considered that the shape of the edge portion between the main surface and the chamfered surface was likely to vary.
  • Example 3 Except for using a glass substrate having a thickness of 0.5 mm, the shape processing and end face polishing steps were performed in the same manner as in Example 1 to produce a magnetic disk glass substrate. Evaluation of the variation in curvature radius of the edge portion between the chamfered surface and the side wall surface at the outer peripheral end surface of the substrate after end surface polishing was performed in the same manner as in Example 1, and the results are shown in Table 3.
  • Comparative Example 5 Except for using a glass substrate having a thickness of 0.5 mm, a shape processing and an end surface polishing step were performed in the same manner as in Comparative Example 3 to produce a magnetic disk glass substrate. Variation evaluation of the curvature radius of the edge portion between the chamfered surface and the side wall surface at the outer peripheral end surface of the substrate after end face polishing was performed in the same manner as in Example 1, and the results are shown in Table 3. The same evaluation results in Example 1 and Comparative Example 3 using a glass substrate having a thickness of 0.635 mm are also shown in Table 3.
  • Example 4 The following film formation process was performed on the magnetic disk glass substrate obtained in Example 1 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. There were no particular obstacles and good results were obtained.
  • SYMBOLS 1 Glass substrate for magnetic discs 2 Outer peripheral end grinding wheel 4 Inner peripheral end grinding grindstone 3, 5 Groove 10 Disc-shaped glass substrate (glass disc) DESCRIPTION OF SYMBOLS 11 Main surface 12 of glass substrate Outer peripheral side end surface 12a Side wall surface 12b Chamfered surface 13 Glass substrate inner peripheral side end surface 13a Side wall surface 13b Chamfered surface 20 End surface polishing apparatus 21, 22 Magnet 23 Spacer 24 Exterior member 26 Magnetic Lump of slurry

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  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)
  • Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
  • Surface Treatment Of Glass (AREA)

Abstract

La présente invention porte sur un procédé de fabrication de substrats en verre pour disques magnétiques, grâce auquel les faces d'extrémité de substrats en verre sont finies en une forme de haute précision et d'une manière de haute qualité. Le traitement de face d'extrémité de la présente invention, qui consiste à traiter les faces d'extrémité de substrats en verre, est réalisé selon le premier processus et le second processus suivants, ce dernier étant réalisé avant le premier processus. Le premier processus consiste à amener la face d'extrémité d'un substrat en verre en contact avec un amas de boue magnétique, qui contient un matériau magnétique et des particules abrasives, formés par maintien de la boue magnétique dans des lignes de champ magnétique. Le second processus consiste à utiliser une meule ayant une forme rainurée, ladite meule étant formée de manière à permettre de traiter simultanément une surface de paroi latérale et des surfaces chanfreinées de la face d'extrémité du substrat en verre, et à incliner le substrat en verre dans la direction de la forme rainurée de la meule.
PCT/JP2013/085292 2012-12-31 2013-12-31 Procédé de fabrication de substrats en verre pour disques magnétiques et procédé de fabrication de disques magnétiques WO2014104377A1 (fr)

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SG11201505032QA SG11201505032QA (en) 2012-12-31 2013-12-31 Method for manufacturing glass substrates for magnetic disks and method for manufacturing magnetic disks
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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
JP2010009723A (ja) * 2008-06-30 2010-01-14 Hoya Corp 磁気ディスク用ガラス基板の加工方法、磁気ディスク用ガラス基板の製造方法、および磁気ディスクの製造方法
JP2011108355A (ja) * 2010-12-20 2011-06-02 Hoya Corp 磁気記録媒体用ガラス基板及びその製造方法

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WO2005005099A1 (fr) * 2003-07-15 2005-01-20 Hoya Corporation Procede et dispositif de fabrication d'un substrat pour un disque magnetique et procede de fabrication d'un disque magnetique
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

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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
JP2010009723A (ja) * 2008-06-30 2010-01-14 Hoya Corp 磁気ディスク用ガラス基板の加工方法、磁気ディスク用ガラス基板の製造方法、および磁気ディスクの製造方法
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