WO2022181715A1 - 磁気ディスク用基板、磁気ディスク、円環形状基板、および磁気ディスク用基板の製造方法 - Google Patents

磁気ディスク用基板、磁気ディスク、円環形状基板、および磁気ディスク用基板の製造方法 Download PDF

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Publication number
WO2022181715A1
WO2022181715A1 PCT/JP2022/007710 JP2022007710W WO2022181715A1 WO 2022181715 A1 WO2022181715 A1 WO 2022181715A1 JP 2022007710 W JP2022007710 W JP 2022007710W WO 2022181715 A1 WO2022181715 A1 WO 2022181715A1
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WO
WIPO (PCT)
Prior art keywords
magnetic disk
substrate
glass plate
side wall
polishing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2022/007710
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English (en)
French (fr)
Japanese (ja)
Inventor
修平 東
利雄 滝澤
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hoya Corp
Original Assignee
Hoya Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hoya Corp filed Critical Hoya Corp
Priority to CN202280015751.3A priority Critical patent/CN116897392A/zh
Priority to JP2023502500A priority patent/JP7467759B2/ja
Priority to US18/547,572 priority patent/US12266389B2/en
Publication of WO2022181715A1 publication Critical patent/WO2022181715A1/ja
Anticipated expiration legal-status Critical
Priority to JP2024059905A priority patent/JP7809741B2/ja
Priority to US19/061,993 priority patent/US20250191612A1/en
Ceased legal-status Critical Current

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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
    • 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
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • G11B5/739—Magnetic recording media substrates
    • G11B5/73911—Inorganic substrates
    • G11B5/73921—Glass or ceramic substrates
    • 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
    • B24B1/00—Processes of grinding or polishing; Use of auxiliary equipment in connection with such processes
    • 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
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C19/00—Surface treatment of glass, not in the form of fibres or filaments, by mechanical means
    • 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
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • 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
    • G11B5/74—Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum
    • G11B5/82—Disk carriers
    • 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

Definitions

  • the present invention relates to a magnetic disk substrate having a pair of main surfaces and an outer peripheral end face, a magnetic disk, an annular substrate, and a method for manufacturing a magnetic disk substrate.
  • HDD hard disk drive
  • a magnetic disk in which a magnetic layer is provided on an annular non-magnetic magnetic disk substrate is used as a storage medium in an HDD device.
  • the end face of the magnetic disk substrate which is the final product, preferably has a smooth surface from the viewpoint of preventing the generation of fine particles. Moreover, it is preferable to align the end face with a target shape from the viewpoint of assembling the magnetic disk into the HDD device with high accuracy.
  • an end surface shape of a magnetic disk substrate a shape having a pair of chamfered surfaces connected to the respective main surfaces and a side wall surface extending in the plate thickness direction between the chamfered surfaces is known.
  • Such an end face shape can be obtained, for example, by performing end face grinding using a formed grindstone having a grinding surface with a shape corresponding to the shape of the target chamfered surface and side wall surface (Patent Document 1).
  • Patent Document 2 there is known an edge-shaped glass substrate having a continuous convex curved surface in a region between a main surface and an outer surface
  • An annular plate (annular substrate) whose end face has been processed into a target shape is further polished on its main surface using a double-sided polishing apparatus.
  • Polishing using a double-sided polishing apparatus double-sided polishing is carried out by holding a ring-shaped substrate in a holding hole of a holding member (carrier) that holds the ring-shaped substrate, and sandwiching the ring-shaped substrate from both upper and lower sides between surface plates. done in the state. At this time, the thickness of the carrier must be thinner than the thickness of the annular substrate.
  • double-side polishing is performed on an annular substrate having a curved end surface, the annular substrate may come off the holding hole of the carrier and ride on the carrier.
  • the thickness of the annular substrate to be polished is thin, the thickness of the carrier needs to be made even thinner, so the annular substrate tends to ride on the carrier. If polishing is continued while the ring-shaped substrate is on the carrier, the main surface is likely to be damaged. Furthermore, when a strong force is applied to the annular substrate sandwiched between the surface plate and the carrier, the annular substrate may be cracked or broken, resulting in damage. The phenomenon described above may occur when both main surfaces of the annular substrate are ground using a holding member.
  • the present invention provides an annular substrate, a magnetic disk substrate, and a magnetic disk, in which the annular substrate is less likely to come off from a holding member that holds the annular substrate when performing double-side grinding or double-side polishing of the annular substrate. , and a method of manufacturing a substrate for a magnetic disk.
  • One aspect of the present invention is a magnetic disk substrate including a pair of main surfaces and an outer peripheral end surface.
  • the magnetic disk substrate is The outer peripheral end surface has a pair of chamfered surfaces connected to the respective main surfaces, and a side wall surface extending between the pair of chamfered surfaces so as to be convex outward,
  • the side wall surface has a curvature radius of 1100 ⁇ m or more in a cross section along the plate thickness direction of the magnetic disk substrate.
  • the radius of curvature of the side wall surface is 2000 ⁇ m or less.
  • the length in the direction parallel to the main surface between the connecting position of the chamfered surface with the main surface and the position of the outermost convexity of the side wall surface is 100 ⁇ m or less.
  • the chamfered surface is curved to be convex outward, It is preferable that the chamfered surface has a radius of curvature smaller than that of the side wall surface in a cross section along the plate thickness direction of the magnetic disk substrate.
  • the radius of curvature of the chamfered surface is preferably 100 to 500 ⁇ m.
  • connection region of the chamfered surface located on the side of the connection position between the chamfered surface and the main surface is parallel to the main surface. It is preferably inclined at an angle of 30 to 70 degrees with respect to the
  • a boundary portion between the chamfered surface and the side wall surface is rounded in a cross section along the plate thickness direction of the magnetic disk substrate.
  • the plate thickness is less than 0.6 mm.
  • the magnetic disk substrate is a substrate made of glass.
  • the magnetic disk is It is characterized by having at least a magnetic film on the surface of the magnetic disk substrate.
  • annular substrate having a pair of main surfaces, and an outer peripheral end face and an inner peripheral end face.
  • the annular substrate is The outer peripheral end surface has a pair of chamfered surfaces connected to the respective main surfaces, and a side wall surface extending between the pair of chamfered surfaces so as to be convex outward,
  • the side wall surface has a curvature radius of 1100 ⁇ m or more in a cross section along the plate thickness direction of the annular substrate.
  • Another aspect of the present invention is a method of manufacturing a magnetic disk substrate, characterized by including a process of polishing at least the main surface of the annular substrate.
  • the annular substrate when the annular substrate is subjected to double-side grinding or double-side polishing, the annular substrate is removed from the holding member that holds the annular substrate. can be made difficult. Further, according to the method for manufacturing a magnetic disk substrate described above, such a magnetic disk substrate can be obtained.
  • FIG. 4 is a diagram showing another example of the cross-sectional shape of the outer peripheral end face of the magnetic disk substrate;
  • a magnetic disk substrate, a magnetic disk, an annular substrate, and a method for manufacturing a magnetic disk substrate according to one embodiment will be described in detail below.
  • a glass substrate is used as the material of the magnetic disk substrate and the annular substrate
  • a metal substrate may be used as a material other than the glass substrate.
  • FIG. 1 is a diagram showing the external shape of a glass substrate, which is an example of a magnetic disk substrate according to one embodiment.
  • the outer circumference of the glass substrate 1 is circular.
  • the glass substrate 1 in the example shown in FIG. 1 is an annular substrate having an inner circumference with an inner hole 3 concentric with the circular circle. That is, the glass substrate 1 of the example shown in FIG. 1 has a pair of main surfaces 1p, 1p (see FIG. 2), an outer peripheral end face 5, and an inner peripheral end face 7.
  • FIG. 1 illustration of a chamfered surface and a side wall surface, which will be described later, of the glass substrate 1 is omitted.
  • the glass substrate 1 is a magnetic disk glass substrate.
  • the size of the glass substrate 1 is not limited, but is, for example, the size of a magnetic disk glass substrate with a nominal diameter of 2.5 inches or 3.5 inches.
  • the outer diameter (diameter) is 55 to 70 mm, for example, the outer diameter is 65 mm, 67 mm, or 58 mm, and the inner hole diameter (diameter) is 20 mm,
  • the plate thickness is 0.3 to 1.3 mm.
  • the outer diameter (diameter) is 85 to 100 mm, for example, the outer diameter is 95 mm, 97 mm, or 89 mm, and the inner hole diameter (diameter) is 25 mm,
  • the plate thickness is 0.3 to 1.3 mm.
  • the plate thickness T (see FIG. 2) of the glass substrate 1 is preferably as thin as possible in that the number of magnetic disks to be mounted on an HDD device can be increased by making the magnetic disk thinner.
  • the order of 0.46 mm or less and 0.41 mm or less is more preferable.
  • the above numerical values for the diameter and plate thickness are nominal values, and may include values that are slightly deviated due to variations in production or the like. Further, when an aluminum alloy substrate with a nickel alloy plating film formed on its surface is used instead of the glass substrate, the above values correspond to the entire substrate including the thickness of the nickel alloy plating film.
  • FIG. 2 shows an example of a cross-sectional shape of the outer peripheral end surface 5 along the plate thickness direction of the glass substrate 1 .
  • the outer peripheral end surface 5 has a pair of chamfered surfaces 1c, 1c and a side wall surface 1t.
  • the pair of chamfered surfaces 1c, 1c are surfaces connected to the main surfaces 1p, 1p, respectively.
  • the chamfered surface is not a flat surface such as a curved surface as described later, it is called a chamfered surface.
  • the side wall surface 1t is a surface that curves and extends outwardly between the chamfered surfaces 1c, 1c.
  • the side wall surface 1t In a cross section along the plate thickness direction of the glass substrate 1 passing through the circular center of the outer circumference of the glass substrate 1 (hereinafter referred to as a cross section along the plate thickness direction or simply a cross section), the side wall surface 1t is: It has a radius of curvature Rt of 1100 ⁇ m or more.
  • the glass substrate 1 having the side wall surface 1t of such a configuration can be obtained by grinding or polishing both sides of an annular substrate made of glass (hereinafter also referred to as a glass plate), which is the base plate of the glass substrate 1. is difficult to come off from the holding hole of the holding member (carrier).
  • the above cross-sectional shape can be measured using a contour shape measuring machine such as a Contracer manufactured by Mitutoyo Co., Ltd., for example.
  • Double-sided grinding or double-sided polishing of the glass plate is performed using a double-sided grinding device or double-sided polishing device equipped with a planetary gear mechanism.
  • double-side grinding using a double-side grinding device or double-side polishing using a double-side polishing device as shown in FIG. , 12.
  • a glass plate G shown in FIG. 3 is sandwiched between surface plates 14 and 12 via a grinding member or polishing pad 20 .
  • illustration of the chamfered surface and the curved side wall surface of the glass plate G is omitted.
  • the thickness of the carrier 18 is thinner than the thickness of the glass plate G in order to secure the machining allowance for both main surfaces of the glass plate G.
  • FIG. 3 illustration of the chamfered surface and the curved side wall surface of the glass plate G is omitted.
  • the main surface of the glass plate G' is likely to be damaged due to contact with the carrier 18.
  • the glass plate may be cracked or broken and damaged.
  • a thinner carrier 18 is used, so the glass plate is more likely to come off from the holding holes 18a.
  • the radius of curvature Rt of the side wall surface 1t is preferably 1200 ⁇ m or more.
  • the glass substrate 1 is manufactured from the glass plate G manufactured by end face processing or end face polishing. is also maintained in Further, when a magnetic film or the like is formed on the surface of the magnetic disk glass substrate 1 to manufacture a magnetic disk described later, the total film thickness of the magnetic film or the like is, for example, 100 nm or less, which is sufficiently thin with respect to the plate thickness. . Therefore, the cross-sectional shape of the side wall surface and the chamfered surface provided on the outer peripheral end surface of the glass substrate 1 is maintained even in the magnetic disk.
  • the outer side means the side away from the center of the circular shape of the outer periphery of the glass substrate 1, and the outward convexity connects both ends in the plate thickness direction of the side wall surface 1t or the chamfered surface 1c. It means that it protrudes outward from a straight line.
  • the curvature radius Rt of the side wall surface 1t is specified as the radius of an arc passing through three specific points on the side wall surface 1t that are different in the plate thickness direction.
  • the radius of curvature Rt of the side wall surface 1t is, for example, a point on the side wall surface 1t that passes through the center of the glass substrate 1 in the plate thickness direction and intersects with a plane parallel to the main surface 1p.
  • a virtual circle with a radius of 100 ⁇ m is drawn centering on T3 and T3
  • it can be specified as the radius of an arc passing through three points of two intersections between the virtual circle and the side wall surface 1t. If the length of the side wall surface 1t is less than 200 ⁇ m and the fitting between the arc of the virtual circle and the side wall surface 1t is not good, the radius of the virtual circle may be appropriately reduced.
  • the cross-sectional shape of the outer peripheral end surface 5 of the glass substrate 1 including the side wall surface 1t can be obtained, for example, by producing a glass plate G using a formed grindstone 30 shown in FIG.
  • FIG. 5 shows a formed grindstone 30 and a plate material (hereinafter referred to as a glass plate material) to be processed into a glass plate G before end face grinding.
  • the broken-line region of the glass plate material indicates the region to be removed by end face grinding.
  • the arrow pointing leftward indicates the direction of relative movement of the formed grindstone 30 with respect to the glass plate during end face grinding.
  • the formed grindstone 30 has, for example, a columnar or cylindrical shape as a whole, and has a groove 31 on the outer peripheral side surface.
  • the groove 31 is configured such that the side wall surface and the chamfered surface of the glass plate G can be formed by grinding at the same time.
  • the groove 31 has a ground surface having a side wall portion 31b and chamfered portions 31a located on both sides thereof.
  • the side wall portion 31b and the chamfered portion 31a of the groove 31 are formed in a predetermined size and shape in consideration of the target finish shape of the outer peripheral end surface of the glass plate G or the glass substrate 1 .
  • the radius of curvature Rt of the sidewall surface 1t is preferably 2000 ⁇ m or less. Since the sidewall surface 1t having a radius of curvature exceeding 2000 ⁇ m extends substantially linearly in the plate thickness direction, the corner between the sidewall surface 1t and the chamfered surface 1c tends to be sharp. When the glass plate G is produced using the formed grindstone 30, the load from the formed grindstone 30 tends to be concentrated on the portion of the glass plate material that becomes such a corner. Therefore, chipping may occur. In particular, since the glass plate material to be the thin glass substrate 1 has a thin plate thickness and tends to lose rigidity, it easily bends under the load from the formed grindstone 30, and the load concentrates on the corner portions. is easy to wake up. In this respect, it is more preferable that the radius of curvature Rt of the side wall surface 1t is 1800 ⁇ m or less.
  • the length Lc in the direction parallel to the main surface 1p is preferably 100 ⁇ m or less.
  • the length Lc is more preferably 80 ⁇ m or less.
  • the upper limit of the length Lc is, for example, 150 ⁇ m.
  • the length Lc is preferably 20 ⁇ m or more in order to prevent chipping during handling of the glass plate G.
  • the degree of sharpness is represented by the value of Lc/T, it is preferable that Lc/T is 0.25 or less. When Lc/T is more than 0.25, the sharpness becomes too large, and the glass plate G may easily come off the holding hole.
  • Lc/T is preferably 0.1 or more. If the Lc/T value is less than 0.1, chipping may easily occur. From these points of view, the Lc/T value is more preferably in the range of 0.1 to 0.25.
  • the chamfered surface 1c is preferably curved so as to be convex outward.
  • the chamfered surface 1c preferably has a radius of curvature Rc smaller than the radius of curvature Rt of the side wall surface 1t in a cross section along the plate thickness direction of the glass substrate 1 .
  • the chamfered surface 1c having the above configuration, the angle formed by the chamfered surface 1c and the side wall surface 1t is less likely to become small (that is, the boundary portion 1b (described later) between the chamfered surface 1c and the side wall surface 1t becomes sharp.
  • the concentration of the load on the part of the glass plate material that becomes the corner between the chamfered surface 1c and the side wall surface 1t is suppressed, and chipping is suppressed. The effect of suppressing the occurrence is improved.
  • the radius of curvature Rc of the chamfered surface 1c is preferably 100-1000 ⁇ m.
  • the radius of curvature Rc when the chamfered surface 1c is curved is specified as the radius of an arc passing through three specific points on the chamfered surface 1c that are different in the plate thickness direction. That is, the radius of curvature Rc of the chamfered surface 1c is (1) the connection position Pc on one main surface side, (2) the position on the chamfered surface 1c at a position 30 ⁇ m in the plate thickness direction from the connection position Pc, ( 3) The position on the chamfered surface at a position 60 ⁇ m in the plate thickness direction from the connection position Pc can be specified as the radius of an arc passing through three points.
  • connection region 1ca of the chamfered surface 1c located on the side of the connection position Pc with the main surface 1p of the chamfered surface 1c is parallel to the main surface 1p. is preferably inclined at an inclination angle ⁇ of 30 to 70 degrees with respect to the direction of By forming the inclined chamfered surface 1c in this way, the connection with the curved side wall surface 1t becomes relatively smooth. The effect of suppressing the occurrence of chipping when the glass plate G is produced using the glass plate G is improved.
  • the connection region 1ca is, for example, a region within a range of 5 to 20 ⁇ m in the plate thickness direction from the connection position Pc.
  • connection position Pc region less than 5 ⁇ m in the plate thickness direction from the main surface 1p
  • the inclination angle ⁇ of the connection region when the connection position Pc is rounded or the chamfered surface 1c is curved is the angle of inclination ⁇ at the position of the connection region 1ca at a position 10 ⁇ m in the plate thickness direction from the connection position Pc.
  • the angle may be such that the tangent line is inclined with respect to the direction parallel to the main surface 1p.
  • the outer peripheral end surface 5 of the glass substrate 1 has a rounded boundary portion 1b (see FIG. 6) between the chamfered surface 1c and the side wall surface 1t in a cross section along the plate thickness direction of the glass substrate 1. preferably.
  • the boundary portion 1b is a portion interposed between the chamfered surface 1c and the side wall surface 1t and connected to the chamfered surface 1c and the side wall surface 1t.
  • the chamfered surface 1c and the side wall surface 1t are connected by a smooth curve, and the cross-sectional shape of the outer peripheral end face 5 as a whole tends to be a smooth curved shape.
  • Such a cross-sectional shape of the outer peripheral end surface 5 suppresses the glass plate G from coming off the holding hole 18a, and suppresses the occurrence of chipping when the glass plate G is produced using the formed grindstone 30. Contribute to improvement.
  • the boundary portion 1b preferably has a radius of curvature of 150 to 1500 ⁇ m, more preferably 150 to 400 ⁇ m, in a cross section along the plate thickness direction of the glass substrate 1. preferable.
  • the radius of curvature of the boundary portion 1b is smaller than the radius of curvature of the side wall surface 1t.
  • the curvature radius R of the boundary portion is obtained as follows.
  • FIG. 6 is a diagram illustrating a method of obtaining the radius of curvature of the cross-sectional shape of the boundary portion 1b. In FIG.
  • Rb is the radius of a circle C2 forming a curvature equivalent to the curvature of the boundary portion 1b in cross-sectional shape, and is the radius of curvature of the shape of the boundary portion 1b.
  • P1 be the point of intersection between the straight line portion of the chamfered surface 1c or the virtual line L1 extending the above arc and the virtual arc L2 extending the side wall surface 1t along the above arc of the side wall surface 1t.
  • a virtual line L3 passing through the intersection point P1 and extending perpendicularly to the virtual line L1 is set.
  • P2 be the intersection of the boundary portion 1b and the virtual line L3.
  • a circle C1 having a predetermined radius (for example, 25 ⁇ m) is set around the intersection point P2.
  • a circle C1 having a predetermined radius for example, 25 ⁇ m
  • two points of intersection between the boundary portion 1b and the outer circumference of the circle C1 are defined as P3 and P4, respectively.
  • a circle C2 passing through each of the three intersections P2, P3 and P4 is set.
  • the radius of curvature Rb of the circle C2 around the portion considered to be the boundary portion 1b is The value when it becomes the smallest may be used.
  • the position of the intersection point P2 may be temporarily set on the end surface, and the circles C2 may be set while appropriately shifting.
  • the intersection point P3 and the intersection point P4 must also be located on the end surface.
  • FIG. 7 is a diagram showing another example of the cross-sectional shape of the outer peripheral end surface 5 of the glass substrate 1.
  • the cross-sectional shape of the outer peripheral end surface 5 of the glass substrate 1 may be a single curved surface shape that is curved as a whole.
  • the cross-sectional shape of the outer peripheral end surface 5 of the glass substrate 1 is such that at least one of the chamfered surface 1c, the connection position Pc, and the boundary portion 1b (T1, T2 in FIG. 2) is curved (or rounded).
  • a length Lt (see FIG. 2) of the side wall surface 1t in the plate thickness direction is not particularly limited, but is, for example, 0.2 to 0.5 mm.
  • a length Lc2 (see FIG. 2) of the chamfered surface 1c in the plate thickness direction is not particularly limited, but is, for example, 0.02 to 0.15 mm.
  • a length Lc1 (see FIG. 2) of chamfered surface 1c in a direction parallel to main surface 1p is not particularly limited, but is, for example, 0.02 to 0.15 mm.
  • the cross-sectional shape of the inner peripheral end face 7 of the glass substrate 1 may be the same as or different from the cross-sectional shape of the outer peripheral end face 5 .
  • a glass plate G which is an example of a ring-shaped substrate of one embodiment, has a ring shape including a pair of main surfaces, an outer peripheral end face and an inner peripheral end face.
  • the outer peripheral end surface of the glass plate G has a pair of chamfered surfaces connected to the respective main surfaces, and a side wall surface extending curvedly outwardly between the chamfered surfaces.
  • the glass plate G has a side wall surface with a curvature radius of 1100 ⁇ m or more in a cross section along the plate thickness direction of the glass plate.
  • the glass plate G is used as the base plate of the glass substrate 1 of the above embodiment.
  • the radius of curvature of the side wall surface of the glass plate G is preferably 2000 ⁇ m or less.
  • the length in the direction parallel to the main surface between the position where the chamfered surface of the glass plate G is connected to the main surface and the position where the side wall surface of the glass plate G is the most outwardly convex is 200 ⁇ m or less.
  • the chamfered surface of the glass plate G is curved so as to protrude outward, and in the cross section along the thickness direction of the glass plate G, the chamfered surface of the glass plate G has the curvature of the side wall surface of the glass plate G It preferably has a radius of curvature smaller than the radius.
  • the radius of curvature of the chamfered surface of the glass plate G is preferably 100 to 500 ⁇ m.
  • connection region of the chamfered surface located on the side of the connection position with the main surface of the chamfered surface is 10 to 70 degrees with respect to the direction parallel to the main surface. is preferably inclined at an angle of The connection area is configured in the same manner as the connection area 1ca of the glass substrate 1 .
  • the boundary portion between the chamfered surface and the side wall surface is rounded.
  • the boundary portion is configured similarly to the boundary portion 1 b of the glass substrate 1 .
  • the plate thickness T of the glass plate G is preferably less than 0.6 mm.
  • a magnetic disk substrate manufacturing method of one embodiment includes a process of polishing at least a main surface of an annular substrate.
  • the ring-shaped substrate to be polished is the ring-shaped substrate of the above embodiment.
  • a case where the glass plate is used as an annular substrate will be described below as an example.
  • the glass plate is not particularly limited, for example, it is made from a glass plate material manufactured by a float method, a down-draw method, or a press method. For example, it is possible to take out a plurality of ring-shaped glass plates having inner holes from a wide sheet-like glass plate manufactured by the float method or the down-draw method.
  • the method of extracting a circular ring-shaped glass plate from a wide sheet-like glass plate may be performed by forming and cutting lines using a well-known scriber (cutter), or by irradiating the glass plate with a laser beam to obtain a circular shape. It may be performed by forming a defect in the shape and cutting it out.
  • the inner hole is a hole that is substantially concentric with the circular shape.
  • Amorphous glass such as aluminosilicate glass, soda lime glass, and borosilicate glass can be used as the glass material for the glass plate.
  • the glass transition temperature Tg of the glass plate is, for example, 450-850.degree.
  • the ring-shaped glass plate material (glass substrate) is made into a glass plate after undergoing edge processing.
  • the end face processing can be performed by end face grinding using a formed grindstone or end face melting in which the end face of the glass plate material is melted by irradiation with a laser beam.
  • end face grinding By using this method, it is possible to form one curved surface shape in which the entire end surface is smoothly curved and connected while avoiding chipping due to grinding.
  • end face polishing for polishing the end face of the glass plate can be further performed.
  • the end surface can be polished using a polishing brush while supplying loose abrasive grains to the end surface.
  • the end face may or may not be polished after the end face processing.
  • the outer peripheral end face of the glass plate can be made into the cross-sectional shape described above by adjusting the shape of the grinding surface of the formed grindstone and the conditions for end face polishing using a polishing brush, for example.
  • various treatments such as grinding, first polishing, second polishing, chemical strengthening, and cleaning, which will be described below, can be performed.
  • the main surface of the glass plate is ground using a double-sided grinder.
  • the glass plate is accommodated in the holding hole of the carrier of the double-side grinding device, and both main surfaces of the glass plate are ground while holding the outer peripheral end face of the glass plate.
  • a double-side grinding machine has a pair of upper and lower surface plates (an upper surface plate and a lower surface plate), and a glass plate is sandwiched between the upper surface plate and the lower surface plate. Then, either one or both of the upper surface plate and the lower surface plate are moved, and the two main surfaces of the glass plate are ground by relatively moving the glass plate and each surface plate while supplying coolant. do.
  • a grinding member formed by forming a sheet of fixed abrasive grains in which diamond is fixed with a resin can be mounted on a surface plate for grinding.
  • a combination of a diamond pad and coolant a combination of a cast iron surface plate and a slurry containing alumina abrasive grains or the like may be used.
  • the thickness of the carrier needs to be smaller than the thickness of the glass plate to be held. A smaller size is more preferable, and a smaller size of 0.15 mm or more is even more preferable.
  • the diameter of the holding hole needs to be larger than the diameter of the glass plate to be held, and may be larger than the diameter of the glass plate by 0.1 to 3.0 mm, for example.
  • the first polishing is applied to the main surface of the glass plate after grinding.
  • the glass plate is accommodated in the holding hole of the carrier of the double-side polishing apparatus, and both main surfaces of the glass plate are polished while holding the outer peripheral end surface of the glass plate.
  • the purpose of the first polishing is to remove scratches and distortions remaining on the main surface after grinding, or to adjust fine surface unevenness (micro-waviness, roughness).
  • the first polishing is preferably mirror polishing.
  • both main surfaces of the glass plate are polished by applying a polishing slurry containing free abrasive grains using a double-sided polishing device having the same configuration as the double-sided polishing device.
  • Abrasive grains such as cerium oxide and zirconia are used as free abrasive grains used in the first polishing.
  • a glass plate is sandwiched between a pair of upper and lower surface plates.
  • a polishing pad (for example, a resin polisher) is attached to the surfaces of the lower surface plate and the upper surface plate.
  • the polishing pad is preferably of a suede type made of resin such as foamed polyurethane and having fine openings on the surface, since the surface of the glass plate is less likely to be damaged and easily mirror-finished. Then, by moving either or both of the upper surface plate and the lower surface plate, the glass plate and each surface plate are relatively moved, thereby polishing both main surfaces of the glass plate.
  • the size of the abrasive grains is preferably in the range of 0.5 to 3 ⁇ m in average particle diameter (D50).
  • the second polishing is applied to the glass plate after the first polishing.
  • the purpose of the second polishing treatment is to mirror polish the main surface.
  • a double-sided polishing apparatus having the same structure as the double-sided polishing apparatus used in the first polishing is used.
  • the glass plate is accommodated in the holding hole of the carrier of the double-sided polishing apparatus, and both main surfaces of the glass plate are polished while holding the outer peripheral end surface of the glass plate.
  • the second polishing treatment differs from the first polishing treatment in the type and particle size of free abrasive grains, and in the hardness of the resin polisher.
  • the hardness of the resin polisher is preferably less than that of the first polishing treatment.
  • a polishing liquid containing colloidal silica as free abrasive grains is supplied between the polishing pad of the double-sided polishing apparatus and the main surface of the glass plate, and the main surface of the glass plate is polished.
  • the size of the abrasive grains used in the second polishing is preferably within the range of 5 to 50 nm in average grain size (d50).
  • the polishing pad it is preferable to use a suede-type polishing pad made of resin such as foamed polyurethane and having fine openings on the surface, because the surface of the glass plate is less likely to be damaged and easily mirror-finished.
  • the chemical strengthening treatment for example, a mixed molten liquid of potassium nitrate and sodium nitrate is used as the chemical strengthening liquid, and the glass sheet is immersed in the chemical strengthening liquid. Thereby, a compressive stress layer can be formed on the surface of the glass plate G by ion exchange. Whether the chemical strengthening treatment is necessary or not is determined in consideration of the glass composition and necessity, and is selected as appropriate.
  • first polishing process and the second polishing process In addition to the first polishing process and the second polishing process, another polishing process may be added, or the first polishing process and the second polishing process may be completed with one polishing process. Also, the order of the above processes may be changed as appropriate.
  • Cleaning is performed using a cleaning liquid (eg, water) after the last polishing treatment or chemical strengthening treatment.
  • a cleaning liquid eg, water
  • another cleaning treatment may be added as appropriate between the steps of grinding, polishing, chemical strengthening, and the like.
  • an aluminum alloy having a nickel alloy film on its surface can be used as a material for the metal substrate.
  • the aluminum alloy for example, an Al--Mg (aluminum--magnesium) alloy containing at least magnesium can be used.
  • the nickel alloy film for example, a plated film of a Ni—P (nickel-phosphorus) alloy containing at least phosphorus can be used.
  • a titanium alloy, single crystal silicon, or the like may be used, and the nickel alloy film may be omitted.
  • an aluminum alloy substrate having a nickel alloy film on its surface can be preferably used because it is relatively lightweight, has high strength, and is easy to process.
  • a disk-shaped plate material (aluminum alloy substrate) is cut from an aluminum alloy plate material, heated at a predetermined temperature and time, and annealed. After that, the main surface is machined and the end faces are shaped. In shaping the end face, the end face is ground or cut into a predetermined shape using a tool such as a formed tool or a single tool.
  • minute recesses may be generated so as to correspond to chipping in the glass plate. This is considered to be due to surface rips and crystallized substances falling off due to sliding between the substrate surface and the tool.
  • the polishing process employs two or more stages of polishing processes in the same manner as the glass plate polishing described above.
  • a specific polishing method can be substantially the same as that for polishing the glass plate described above, except that a polishing liquid containing alumina abrasive grains is preferably used in the first polishing (rough polishing).
  • the annular substrate having the outer peripheral end face having the above-described cross-sectional shape After manufacturing the annular substrate having the outer peripheral end face having the above-described cross-sectional shape, at least the main surface of the annular substrate is polished to obtain a magnetic disk substrate that satisfies the conditions required for a magnetic disk substrate. is manufactured. Thereafter, a magnetic disk is manufactured by forming at least a magnetic film on the main surface of the magnetic disk substrate. Then, an HDD including the magnetic disk and the magnetic head is manufactured.
  • a magnetic disk of one embodiment has at least a magnetic film on the surface of a magnetic disk substrate.
  • the magnetic film is preferably formed at least on the main surface of the magnetic disk substrate, but is generally also formed on the end surfaces of the magnetic disk substrate.
  • the magnetic disk preferably has films such as a base film, a magnetic film, and a protective film in order from the surface side of the magnetic disk substrate.
  • a glass plate having the following specifications was used for the first polishing. Note that all the specifications regarding the end face are related to the outer peripheral end face. ⁇ Outer diameter 97mm, inner diameter 25mm, plate thickness 0.53mm ⁇ The radius of curvature Rt is as shown in Table 1. ⁇ The chamfered surface has a substantially linear shape in cross section. ⁇ The radius of curvature of the boundary between the side wall surface and the chamfered surface is less than 150 ⁇ m. ⁇ A ring-shaped glass plate made of aluminosilicate glass. 12.5 ⁇ m on each side). Moreover, the thickness of the carrier was set to 0.3 mm.
  • the first polishing was carried out by accommodating a total of 25 glass plates G in 5 carriers each having 5 holding holes (1 batch: 25 plates). Such first polishing was performed 20 times, and each time the first polishing was completed, the number of glass plates that had fallen out of the holding holes and landed on the carrier was counted. It was rated A when it was less than 2% of the total number of sheets, B when it was 2% or more and less than 4%, and C when it was 4% or more. If the evaluation is A or B, the frequency (occurrence rate) of detachment of the glass plate from the holding hole is low, and thus it is acceptable. Table 1 shows the results.
  • Example 1-2 In the specifications of the glass plate used for the first polishing, the first polishing was performed under the same conditions as in Experimental Example 1-1 and Table 1, except that the plate thickness was changed to 0.48 mm (Comparative Examples 3 and 4 , Examples 5 to 8), and the same results as in Table 1 were obtained.
  • Example 1-3 The first polishing was performed under the same conditions as in Experimental Example 1-1 and Table 1, except that the thickness of the glass plate used for the first polishing was changed to 0.43 mm (Comparative Examples 5 and 6 , Examples 9 to 12), and the same results as in Table 1 were obtained.
  • Example 1-4 Except for changing the ring-shaped substrate used for the first polishing to a glass plate, to a substrate having a NiP alloy plated film of 10 ⁇ m on the surface of an aluminum alloy substrate, and changing the free abrasive grains to alumina abrasive grains, the experiment was carried out.
  • the first polishing was performed under the same conditions as in Example 1-1 and Table 1 (Comparative Examples 7 and 8 and Examples 13 to 16), results similar to those in Table 1 were obtained.
  • Example 1-5 The annular substrate used for the first polishing was replaced with a glass plate, and a substrate with a plate thickness of 0.48 mm was formed by forming a NiP alloy plating film of 10 ⁇ m on the surface of an aluminum alloy substrate, and free abrasive grains were replaced with alumina abrasive grains. Except for the change, the first polishing was performed under the same conditions as in Experimental Example 1-1 and Table 1 (Comparative Examples 9 and 10, Examples 17 to 20), and the same results as in Table 1 were obtained. .
  • Example 1--7 In the specifications of the glass plate used for the first polishing, the plate thickness was changed to 0.43 mm, and the curvature radius of the boundary portion between the side wall surface and the chamfered surface was changed to be within the range of 150 to 400 ⁇ m.
  • the first polishing was performed under the same conditions as in Experimental Example 1-1 and Table 1 (Comparative Examples 13 and 14 and Examples 25 to 28), results similar to those in Table 1 were obtained.
  • Example 1-8 Except for the fact that the glass plate used in the first polishing was melted with a laser beam and then ground on both main surfaces to form an outer peripheral end face that looks like one curved surface that is smoothly curved and connected as a whole.
  • the evaluation of the frequency of occurrence of detachment from the holding holes was A.
  • the specifications of the outer peripheral end face are as follows. ⁇ The curvature radius Rt is 1500 ⁇ m ⁇ The chamfered surface has a curved shape with a curvature radius of 200 to 500 ⁇ m in cross section, an inclination angle of 40° in the connection area with the main surface, and Lc of 100 ⁇ m. ⁇ The curvature radius of the boundary between the side wall surface and the chamfered surface is 100 to 500 ⁇ m.
  • the second polishing was performed with a removal allowance of 5 ⁇ m (2.5 ⁇ m on one side) based on the plate thickness.
  • the total removal amount of the first polishing and the second polishing is 30 ⁇ m based on the plate thickness. For example, if the plate thickness before the first polishing is 0.53 mm, the plate thickness after the second polishing is 0.50 mm. .
  • a polishing liquid containing colloidal silica and a suede pad were used.
  • a glass plate material having the following specifications was used for end face grinding. Note that all the specifications regarding the end face are related to the outer peripheral end face. ⁇ Outer diameter 98mm, inner diameter 24mm, plate thickness 0.59mm ⁇ The shape of the end face extending substantially perpendicularly to the main surface in cross section ⁇ Annular plate material made of aluminosilicate glass The cutting allowance for end face grinding was set to 1 mm based on the diameter for both the outer diameter and the inner diameter.
  • the target shape of the chamfered surface of the glass plate after end face grinding is a linear shape in cross section
  • the inclination angle of the connection area is 45°
  • the length in the plate thickness direction is 115 ⁇ m
  • Lt 360 ⁇ m
  • Lc is equal to Rt.
  • the curvature radius of the boundary portion between the side wall surface and the chamfered surface was set to be less than 150 ⁇ m.
  • the side wall surface of the outer peripheral end face of the glass plate after the end face grinding has a shape extending linearly in the plate thickness direction.
  • each experimental example 500 glass plate materials were processed using a formed grindstone having a grinding surface with a shape corresponding to the above target shape and the curvature radius Rt shown in Table 2 below, and the glass plate after end face grinding was finished.
  • the outer peripheral end face of each was inspected in a dark room using a condensing lamp, and the number of sheets with chipping (chipping) was counted to calculate the chipping occurrence frequency (occurrence rate).
  • the total number of plate materials with chipping was less than 2% of the total, it was evaluated as A, and when it was 2% or more, it was evaluated as B.
  • the frequency of chipping is reduced by producing a glass plate having a side wall surface with a radius of curvature Rt of 2000 ⁇ m or less. If chipping occurs on the end face of the glass plate, it is not preferable from the viewpoint of production efficiency because, for example, it is necessary to increase the machining allowance in the subsequent end face polishing, and the number of defective products increases.
  • Example 2-2 In the target shape of the chamfered surface of the glass plate after end face grinding, the experiment was performed except that the shape of the formed grindstone was changed so that the radius of curvature of the boundary portion between the side wall surface and the chamfered surface was within the range of 150 to 400 ⁇ m.
  • the end face grinding was performed under the same conditions as in Example 2-1 and Examples 101 to 104 in Table 2 (Examples 105 to 108), the frequency of chipping occurrence was 90% or less in each of the corresponding Examples. was found to be reduced to

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PCT/JP2022/007710 2021-02-24 2022-02-24 磁気ディスク用基板、磁気ディスク、円環形状基板、および磁気ディスク用基板の製造方法 Ceased WO2022181715A1 (ja)

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JP2009173295A (ja) * 2008-01-22 2009-08-06 Konica Minolta Opto Inc 記録媒体用ガラス基板の収納容器、記録媒体用ガラス基板収納体、記録媒体用ガラス基板の製造方法、記録媒体用ガラス基板及び記録媒体
JP5574392B1 (ja) * 2012-09-28 2014-08-20 Ｈｏｙａ株式会社 磁気ディスク用ガラス基板、磁気ディスク

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JP4911882B2 (ja) 2004-07-23 2012-04-04 コニカミノルタオプト株式会社 情報記録媒体用ガラス基板、情報記録媒体、および情報記録装置
JP2006079800A (ja) * 2004-08-11 2006-03-23 Showa Denko Kk 磁気記録媒体用シリコン基板及びその製造方法並びに磁気記録媒体
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