US20240066665A1 - Grindstone - Google Patents

Grindstone Download PDF

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Publication number
US20240066665A1
US20240066665A1 US18/446,658 US202318446658A US2024066665A1 US 20240066665 A1 US20240066665 A1 US 20240066665A1 US 202318446658 A US202318446658 A US 202318446658A US 2024066665 A1 US2024066665 A1 US 2024066665A1
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United States
Prior art keywords
filler
binder
grinding
workpiece
grindstone
Prior art date
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Pending
Application number
US18/446,658
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English (en)
Inventor
Hidenori Nagai
Takashi Yamaguchi
Naruto Fuwa
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Disco Corp
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Disco Corp
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Filing date
Publication date
Application filed by Disco Corp filed Critical Disco Corp
Assigned to DISCO CORPORATION reassignment DISCO CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: FUWA, NARUTO, NAGAI, HIDENORI, YAMAGUCHI, TAKASHI
Publication of US20240066665A1 publication Critical patent/US20240066665A1/en
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
    • B24D3/04—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic
    • B24D3/14—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic ceramic, i.e. vitrified bondings
    • B24D3/18—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic ceramic, i.e. vitrified bondings for porous or cellular structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D7/00—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting otherwise than only by their periphery, e.g. by the front face; Bushings or mountings therefor
    • B24D7/06—Bonded abrasive wheels, or wheels with inserted abrasive blocks, designed for acting otherwise than only by their periphery, e.g. by the front face; Bushings or mountings therefor with inserted abrasive blocks, e.g. segmental
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/34—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties
    • B24D3/342—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents characterised by additives enhancing special physical properties, e.g. wear resistance, electric conductivity, self-cleaning properties incorporated in the bonding agent
    • 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
    • B24B7/00—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor
    • B24B7/20—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground
    • B24B7/22—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain
    • B24B7/228—Machines or devices designed for grinding plane surfaces on work, including polishing plane glass surfaces; Accessories therefor characterised by a special design with respect to properties of the material of non-metallic articles to be ground for grinding inorganic material, e.g. stone, ceramics, porcelain for grinding thin, brittle parts, e.g. semiconductors, wafers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
    • B24D3/04—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic
    • B24D3/06—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic metallic or mixture of metals with ceramic materials, e.g. hard metals, "cermets", cements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
    • B24D3/04—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic
    • B24D3/14—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially inorganic ceramic, i.e. vitrified bondings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
    • B24D3/20—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially organic
    • B24D3/28—Resins or natural or synthetic macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D3/00—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents
    • B24D3/02—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent
    • B24D3/20—Physical features of abrasive bodies, or sheets, e.g. abrasive surfaces of special nature; Abrasive bodies or sheets characterised by their constituents the constituent being used as bonding agent and being essentially organic
    • B24D3/28—Resins or natural or synthetic macromolecular compounds
    • B24D3/32—Resins or natural or synthetic macromolecular compounds for porous or cellular structure

Definitions

  • the present invention relates to a grindstone used for processing a workpiece.
  • Device chips including devices are manufactured by dividing and individualizing a wafer formed with a plurality of devices.
  • a package substrate is formed by mounting a plurality of device chips on a predetermined substrate and covering the device chips with a resin layer (molding resin) to seal the device chips.
  • a resin layer molding resin
  • package devices including a plurality of packaged device chips are manufactured.
  • the device chips and the package devices are incorporated into various electronic apparatuses such as mobile phones and personal computers.
  • the grinding apparatus includes a chuck table for holding a workpiece and a grinding unit for grinding the workpiece.
  • the grinding unit includes a spindle, and an annular grinding wheel including a plurality of grindstones is mounted to a tip end part of the spindle.
  • the workpiece is held by the chuck table, and, while the chuck table and the grinding wheel are rotated, grinding surfaces of the grindstones are brought into contact with the workpiece to grind the workpiece (see Japanese Patent Laid-open No. 2000-288881).
  • the grindstones used for grinding the workpiece are formed by fixing abrasive grains with a binder (bond material).
  • a binder bond material
  • a mixture containing diamond abrasive grains and a vitrified bond material is kneaded and granulated, followed by compression molding and firing, whereby a vitrified bond grindstone is obtained (see Japanese Patent Laid-open No. 2006-1007).
  • the binder of the grindstone contains a filler (aggregate) for reinforcing the binder.
  • a filler typically, ceramic particles having an angular random shape (angular shape) are used. Addition of the filler to the binder enhances mechanical strength of the binder and prolongs the useful life of the binder. As a result, the cost of the grindstone is lowered, and lowering in processing efficiency attendant on replacing work of the grindstone is restrained. In addition, it has been confirmed that use of a filler of a larger size further enhances the strength of the binder.
  • the present invention has been made in consideration of such a problem, and it is an object of the invention to provide a grindstone which is high in strength and is capable of restraining occurrence of defective processing.
  • a grindstone including abrasive grains and a binder for fixing the abrasive grains, in which the binder contains a spherical filler for reinforcing the binder.
  • the average particle diameter of the filler is greater than the average particle diameter of the abrasive grains.
  • the filler is ceramic particles, and the ratio of a short axis to a long axis of the ceramic particles is not less than 0.7.
  • the content of the filler in the binder is 5 to 90 wt %.
  • the binder is a vitrified bond or a resin bond.
  • the binder for fixing the abrasive grains contains the spherical filler.
  • FIG. 1 is a perspective view depicting a grinding apparatus
  • FIG. 2 is a perspective view depicting a grinding wheel
  • FIG. 3 is a sectional view depicting a part of a grindstone
  • FIG. 4 is a graph depicting the results of measurement of strengths of grindstones.
  • FIG. 1 is a perspective view depicting a grinding apparatus 2 for grinding a workpiece 11 .
  • an X-axis direction (a first horizontal direction, a front-rear direction) and a Y-axis direction (a second horizontal direction, a left-right direction) are mutually perpendicular directions.
  • a Z-axis direction (a height direction, a vertical direction, an up-down direction) is a direction perpendicular to both the X-axis direction and the Y-axis direction.
  • the workpiece 11 is a disk-shaped wafer formed of a semiconductor material such as single crystal silicon, and has a front surface (a first surface) 11 a and a back surface (a second surface) 11 b which are substantially parallel to each other.
  • the workpiece 11 is partitioned into a plurality of rectangular regions by a plurality of streets (scheduled division lines) arranged in a grid pattern in such a manner as to mutually intersect.
  • streets such devices (not illustrated) as integrated circuits (ICs), large scale integration (LSI) circuits, light emitting diodes (LEDs), and micro electro mechanical systems (MEMS) devices are formed respectively on the front surface 11 a side of the plurality of regions partitioned by the streets.
  • ICs integrated circuits
  • LSI large scale integration
  • LEDs light emitting diodes
  • MEMS micro electro mechanical systems
  • a plurality of device chips respectively provided with the devices are manufactured.
  • various processing apparatuses such as a cutting apparatus for cutting the workpiece 11 by an annular cutting blade and a laser processing apparatus for processing the workpiece 11 by applying a laser beam.
  • a cutting apparatus for cutting the workpiece 11 by an annular cutting blade and a laser processing apparatus for processing the workpiece 11 by applying a laser beam.
  • the back surface 11 b side of the workpiece 11 is preliminarily ground by the grinding apparatus 2 to thin the workpiece 11 prior to the division of the workpiece 11 , thinned device chips are obtained.
  • the kind, material, size, shape, structure, and the like of the workpiece 11 are not limited to any particular ones.
  • the workpiece 11 may be a wafer (substrate) formed of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramic, resin, metal, or the like.
  • the kinds, number, shapes, structures, sizes, layout, and the like of the devices are not limited to any particular ones, and the workpiece 11 may not be formed with the devices.
  • the grinding apparatus 2 includes a base 4 for supporting or accommodating each of constituent elements constituting the grinding apparatus 2 .
  • a rectangular opening 4 a is formed such that the longitudinal direction thereof extends along the X-axis direction.
  • a rectangular parallelepiped support structure 6 is provided along the Z-axis direction.
  • a chuck table (a holding table) 8 for holding the workpiece 11 On the inside of the opening 4 a , a chuck table (a holding table) 8 for holding the workpiece 11 is provided.
  • An upper surface of the chuck table 8 is a flat surface substantially parallel to a horizontal plane (XY plane), and constitutes a holding surface 8 a for holding the workpiece 11 .
  • the holding surface 8 a is connected to a suction source (not illustrated) such as an ejector through a flow channel (not illustrated) formed inside the chuck table 8 , a valve (not illustrated), and the like.
  • An X-axis moving unit 10 for moving the chuck table 8 along the X-axis direction is connected to the chuck table 8 .
  • the X-axis moving unit 10 is, for example, a ball screw type moving mechanism, and is provided inside the opening 4 a .
  • the X-axis moving unit 10 includes an X-axis ball screw (not illustrated) disposed along the X-axis direction and an X-axis pulse motor (not illustrated) for rotating the X-axis ball screw.
  • the X-axis moving unit 10 includes a flat plate-shaped table cover 12 provided in such a manner as to surround the chuck table 8 .
  • bellows-like dustproof and droplet-proof covers 14 capable of contracting and extending in the X-axis direction are provided.
  • the table cover 12 and the dustproof and droplet-proof covers 14 are provided in such a manner as to cover the constituent elements (the X-axis ball screw, the X-axis pulse motor, and the like) of the X-axis moving unit 10 accommodated inside the opening 4 a .
  • the chuck table 8 is moved in the X-axis direction together with the table cover 12 , and is positioned at a front end part (conveying position) or a rear end part (grinding position) of the opening 4 a .
  • a rotational drive source such as a motor for rotating the chuck table 8 around a rotational axis substantially parallel to the Z-axis direction is connected to the chuck table 8 .
  • a Z-axis moving unit 16 On a front surface side of the support structure 6 , a Z-axis moving unit 16 is provided.
  • the Z-axis moving unit 16 includes a pair of Z-axis guide rails 18 disposed along the Z-axis direction.
  • a flat plate-shaped Z-axis moving plate 20 is mounted to the pair of Z-axis guide rails 18 in such a manner as to be slidable along the Z-axis guide rails 18 .
  • a nut section On a back surface side (a rear surface side) of the Z-axis moving plate 20 , a nut section (not illustrated) is provided. The nut section is in screw engagement with a Z-axis ball screw 22 disposed along the Z-axis direction between the pair of Z-axis guide rails 18 .
  • a Z-axis pulse motor 24 for rotating the Z-axis ball screw 22 is connected to an end part of the Z-axis ball screw 22 .
  • the Z-axis moving plate 20 is moved (lifted or lowered) in the Z-axis direction along the Z-axis guide rails 18 .
  • a support member 26 is fixed to a front surface side of the Z-axis moving plate 20 .
  • the support member 26 supports a grinding unit 28 for grinding the workpiece 11 .
  • the grinding unit 28 includes a cylindrical housing 30 supported by the support member 26 .
  • a cylindrical spindle 32 disposed along the Z-axis direction is accommodated in the housing 30 .
  • a tip end part (a lower end part) of the spindle 32 projects downward from a lower surface of the housing 30 .
  • a rotational drive source (not illustrated) such as a motor is connected to a base end part (an upper end part) of the spindle 32 .
  • a disk-shaped wheel mount 34 made of metal or the like is fixed to the tip end part of the spindle 32 .
  • An annular grinding wheel 36 for grinding the workpiece 11 is detachably mounted to a lower surface side of the wheel mount 34 .
  • the grinding wheel 36 includes an annular wheel base 38 and a plurality of grindstones 40 fixed to the wheel base 38 .
  • the grinding wheel 36 is rotated around a rotational axis substantially parallel to the Z-axis direction by motive power transmitted from the rotational drive source through the spindle 32 and the wheel mount 34 . Note that the configuration and functions of the grinding wheel 36 will be described later (see FIG. 2 ).
  • the grinding apparatus 2 includes a controller (control unit, control section, control device) 42 for controlling the grinding apparatus 2 .
  • the controller 42 is connected to each of constituent elements (the chuck table 8 , the X-axis moving unit 10 , the Z-axis moving unit 16 , the grinding unit 28 , etc.) of the grinding apparatus 2 .
  • the controller 42 sends control signals to the constituent elements of the grinding apparatus 2 to thereby control the operation of the grinding apparatus 2 .
  • the controller 42 includes a computer.
  • the controller 42 includes a processing section for performing calculations and the like for the operation of the grinding apparatus 2 and a storage section for storing various kinds of information (data, a program, and the like) used for the operation of the grinding apparatus 2 .
  • the processing section includes a processor such as a central processing unit (CPU).
  • the storage section includes a memory such as a read only memory (ROM) and a random access memory (RAM).
  • the workpiece 11 is held by the chuck table 8 .
  • the workpiece 11 is disposed on the chuck table 8 such that the front surface 11 a side faces the holding surface 8 a and the back surface 11 b side is exposed to the upper side.
  • a suction force (negative pressure) of the suction source is made to act on the holding surface 8 a , whereby the workpiece 11 is held under suction by the chuck table 8 .
  • the chuck table 8 is moved by the X-axis moving unit 10 , and is positioned on the lower side of the grinding wheel 36 (grinding position).
  • the grinding wheel 36 is lowered at a predetermined speed by the Z-axis moving unit 16 , to bring the grindstones 40 into contact with the workpiece 11 .
  • the back surface 11 b side of the workpiece 11 is ground away, and the workpiece 11 is ground and thinned.
  • the grinding wheel 36 is fixed to the wheel mount 34 (see FIG. 1 ) by fixing means (not illustrated) such as fastening bolts, for example. As a result, the grinding wheel 36 is mounted to the tip end part of the spindle 32 through the wheel mount 34 .
  • FIG. 2 is a perspective view depicting the grinding wheel 36 including the wheel base 38 and the plurality of grindstones 40 .
  • the wheel base 38 is formed of such metal as an aluminum alloy, and is formed in an annular shape substantially equal in diameter to the wheel mount 34 (see FIG. 1 ).
  • the wheel base 38 includes a first surface 38 a and a second surface 38 b which are substantially parallel to each other.
  • the first surface 38 a corresponds to a fixed end face fixed to the wheel mount 34 (see FIG. 1 )
  • the second surface 38 b corresponds to a free end face which is not fixed to the wheel mount 34 .
  • the wheel base 38 is provided in a central part thereof with an opening 38 c penetrating the wheel base 38 in the thickness direction from the first surface 38 a to the second surface 38 b .
  • the opening 38 c is formed in a frustoconical shape whose diameter increases from the first surface 38 a toward the second surface 38 b .
  • an annular groove 38 d is provided on the second surface 38 b side of the wheel base 38 .
  • the groove 38 d is formed concentrically with the wheel base 38 on the outer circumferential side of the wheel base 38 than the opening 38 c .
  • the plurality of grindstones 40 for grinding the workpiece 11 are fixed.
  • the plurality of grindstones 40 are each formed, for example, in a rectangular parallelepiped shape, and are arranged in an annular pattern at substantially equal intervals along the groove 38 d .
  • the width of the grindstones 40 and the width of the groove 38 d are substantially equal, and the grindstones 40 are arranged such that the lengthwise direction (longitudinal direction) thereof is along the tangential direction (circumferential direction) of the groove 38 d .
  • the grindstone 40 includes a rectangular grinding surface 40 a which is exposed to the side opposite to the wheel base 38 .
  • the grinding surface 40 a is a surface that comes into contact with the workpiece 11 at the time of grinding, and the workpiece 11 is ground by the grinding surface 40 a.
  • the wheel base 38 includes a plurality of grinding liquid supply passages 38 e penetrating the wheel base 38 from the first surface 38 a to the second surface 38 b .
  • One end side of the grinding liquid supply passage 38 e is opened in the first surface 38 a
  • the other end side of the grinding liquid supply passage 38 e is opened in that region of the second surface 38 b which is located between the opening 38 c and the groove 38 d .
  • the openings of the plurality of grinding liquid supply passages 38 e exposed in the second surface 38 b are arranged in an annular pattern at substantially equal intervals along the circumferential direction of the wheel base 38 .
  • the grinding wheel 36 is mounted to the wheel mount 34 which is fixed to the tip end part of the spindle 32 .
  • the grinding wheel 36 is rotated around a rotational axis which is substantially parallel to the Z-axis direction.
  • the plurality of grindstones 40 are each rotated (slewed) along an annular rotational route centered on a rotational axis of the grinding wheel 36 .
  • the workpiece 11 is ground.
  • liquid such as pure water is supplied to one end side of the grinding liquid supply passage 38 e (the first surface 38 a side of the wheel base 38 ), and the grinding liquid is supplied from the other end side of the grinding liquid supply passage 38 e to the workpiece 11 and the plurality of grindstones 40 .
  • the workpiece 11 and the grindstones 40 are cooled, and swarf (grinding swarf) generated by grinding of the workpiece 11 is washed away.
  • FIG. 3 is a sectional view depicting a part of the grindstone 40 .
  • the grindstone 40 includes abrasive grains 50 formed of diamond, cubic boron nitride (cBN), or the like and a binder (bonding material) 52 for fixing the abrasive grains 50 .
  • the binder 52 there can be used a vitreous vitrified bond containing SiO 2 or the like as a main constituent, a resin bond containing resin as a main constituent, or the like.
  • a number of pores are formed inside the binder 52 . It is to be noted, however, that the material and grain diameter of the abrasive grains 50 and the material of the binder 52 are not limited to any kind.
  • the binder 52 contains a filler (aggregate) 54 for reinforcing the binder 52 .
  • a filler (aggregate) 54 for reinforcing the binder 52 .
  • the filler 54 contained in the binder 52 , mechanical strength of the binder 52 is enhanced, and consumption of the grindstones 40 is suppressed.
  • a spherical filler 54 is contained in the binder 52 .
  • the filler 54 does not have an angular random shape (angular shape), and is particles (powder material) having a true spherical shape or a shape resembling a true sphere.
  • the ratio of a short axis a to a long axis b (aspect ratio a/b) of the filler 54 is not less than 0.7, preferably not less than 0.8, and more preferably not less than 0.9.
  • the short axis a of the filler 54 passes through the center (center of gravity) of the filler 54 and corresponds to the length of a shortest straight line connecting two points on the surface of the filler 54 .
  • the long axis b of the filler 54 passes through the center (center of gravity) of the filler 54 and corresponds to the length of a longest straight line connecting two points on the surface of the filler 54 .
  • the short axis a corresponds to a short diameter of the filler 54
  • the long axis b corresponds to a long diameter of the filler 54
  • the circularity of the filler 54 is, for example, not less than 0.95, preferably not less than 0.96, and more preferably not less than 0.97.
  • the convexity of the filler 54 is, for example, not less than 0.97, preferably not less than 0.98, and more preferably not less than 0.99, and the solidity of the filler 54 is, for example, not less than 0.94, preferably not less than 0.95, and more preferably not less than 0.96.
  • spherical ceramic particles formed of aluminum oxide (alumina, Al 2 O 3 ), silicon dioxide (silica, SiO 2 ), or the like are used as the filler 54 .
  • As a commercial product which can be used as the filler 54 there may be mentioned true spherical fine particles (trade name: ADMAFINE (registered trademark)) made by ADMATECHS COMPANY LIMITED.
  • the amount of the filler 54 contained in the binder 52 is adjusted according to the strength of the binder 52 required.
  • the content of the filler 54 in the binder 52 can be set to be 5 to 90 wt %, and preferably 60 to 80 wt %. This content corresponds to the ratio of the mass of the filler 54 based on the mass of the binder 52 in which the filler 54 is contained (the total of the mass of the binder 52 and the mass of the filler 54 ).
  • the strength of the binder 52 is high as compared to the case where a filler of an angular shape is used (see FIG. 4 ).
  • the strength of the binder 52 is higher as the size of the filler 54 is greater (see FIG. 4 ).
  • the average particle diameter of the filler 54 be greater than the average particle diameter of the abrasive grains 50 .
  • the average particle diameter of the filler 54 is 1.1 to 20 times the average particle diameter of the abrasive grains 50 .
  • the particle diameters of the abrasive grains 50 and the filler 54 can be measured, for example, by a laser diffraction method.
  • the filler 54 has an angular shape
  • the sharp angular parts of the filler 54 largely project from the binder 52 to be liable to collide against the workpiece 11 , and defective processing may occur.
  • the spherical filler 54 is used as in the present embodiment, even if the filler 54 projects from the binder 52 , only a smooth surface (curved surface) of the filler 54 would make contact with the workpiece 11 .
  • the average particle diameter of the filler 54 is greater than the average particle diameter of the abrasive grains 50 , damaging of the workpiece 11 by the filler 54 is not liable to occur, and defective processing is restrained.
  • the binder 52 for fixing the abrasive grains 50 contains the spherical filler 54 . As a result, it is possible to restrain occurrence of defective processing at the time of processing the workpiece 11 by the grindstones 40 , while enhancing the strength of the grindstones 40 .
  • a plurality of rectangular parallelepiped grindstones (with the length of 20 mm, the width of 10 mm, and the thickness of 4 mm) containing no abrasive grains but fillers in the binder (vitrified bons) were used.
  • a grindstone A containing aluminum oxide of an angular shape as the filler, a grindstone B containing spherical aluminum oxide as the filler, and a grindstone C containing spherical silicon dioxide as the filler were formed.
  • two kinds of grindstones A, four kinds of grindstones B, and three kinds of grindstones C, which were different in particle diameter of the filler were prepared.
  • the particle diameters of the filler (aluminum oxide of angular shape) contained in the two kinds of grindstones A were 0.5 ⁇ m and 2 ⁇ m.
  • the particle diameters of the filler (spherical aluminum oxide) contained in the four kinds of grindstones B were 0.7 ⁇ m, 4.2 ⁇ m, 5 ⁇ m, and 5.4 ⁇ m.
  • the particle diameters of the filler (spherical silicon dioxide) contained in the three kinds of grindstones C were 1.6 ⁇ m, 3 ⁇ m, and 5.7 ⁇ m.
  • FIG. 4 is a graph depicting the measurement results of the strength of the grindstones.
  • the strength of the grindstone was higher as the particle diameter of the filler was greater.
  • enlargement of the filler is effective for enhancing the strength of the grindstone.
  • a grindstone B having a strength of not less than 10 MPa, not less than 30 MPa, or not less than 40 MPa was obtained.
  • a grindstone C having a strength of not less than 5 MPa or not less than 10 MPa was obtained.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Polishing Bodies And Polishing Tools (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)
US18/446,658 2022-08-31 2023-08-09 Grindstone Pending US20240066665A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022138453A JP2024034299A (ja) 2022-08-31 2022-08-31 砥石
JP2022-138453 2022-08-31

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US20240066665A1 true US20240066665A1 (en) 2024-02-29

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