JP2012228746A - Grinding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with the electrode position accuracy of high accuracy, to prevent any defective electrode contact, and to easily attach/detach a grinding wheel when the grinding wheel for executing the grinding with the ultrasonic vibration is mounted on a wheel mount and used.SOLUTION: A movable electrode 72 for supplying the high frequency power to an ultrasonic vibrator 6 is disposed on a grinding wheel 33. The movable electrode 72 is formed of a material to be attracted by the magnetic force, and accommodated in a case 74 by a spring member 73. A fixed electrode 38 with the magnetic force is disposed on the wheel mount 32 on the outer circumferential side of the movable electrode 72. When the grinding wheel 33 is fastened to the wheel mount 32 by screws 321, the electrodes are disposed opposite to each other. Since the movable electrode 72 and the fixed electrode 38 are brought into contact with each other by the magnetic force, the electrodes can be easily coupled with each other, and only by attaching/detaching the grinding wheel 33 to/from the wheel mount 32, the movable electrode 72 and the fixed electrode 38 can be easily attached/detached to/from each other.

Description

  The present invention relates to a grinding apparatus for grinding a workpiece with ultrasonic vibration.

  A wafer in which a plurality of devices such as IC, LSI, etc. are partitioned by a line to be divided and formed on the surface is divided into individual devices by a dividing device such as a cutting device and used for various devices such as mobile phones and personal computers. Yes. Before the wafer is divided into devices, the back surface is ground by a grinding wheel equipped with a grinding wheel to have a predetermined thickness.

  In addition, when grinding brittle hard materials such as sapphire, silicon nitride, lithium tantalate, and Altic using a grinding device, it takes a long time and productivity is low. A grinding device for grinding a workpiece while the grinding wheel vibrates ultrasonically was developed and applied for a patent (see Patent Document 1).

  In the grinding apparatus described in Patent Document 1, a power supply means is connected to an end of a rotary spindle connected to a wheel mount that supports a grinding wheel, and a cavity formed in the longitudinal direction of the axis of the rotary spindle is formed. The conductive wire extends through the wheel mount. The wheel mount is formed with a concave connector to which conductive wires are connected. When this concave connector is connected to the convex connector formed on the grinding wheel, the ultrasonic transducer connected to the convex connector is connected. High frequency power is supplied to the grinding wheel to vibrate.

  In such a grinding apparatus, when the grinding wheel is attached to and detached from the wheel mount, the concave connector and the convex connector have to be attached and detached, which is troublesome. Therefore, the present applicant has developed and applied for a patent for a grinding apparatus that can easily attach and detach the grinding wheel to and from the wheel mount (see Patent Document 2).

  In the grinding apparatus described in Patent Document 2, an annular ultrasonic vibrator is disposed on a grinding wheel, and two annular electrodes that are electrically connected to the ultrasonic vibrator are provided around the annular ultrasonic vibrator. By mounting the grinding wheel on the wheel mount, the two annular electrodes come into contact with the two electrodes provided at the lower end of the wheel mount, and the grinding wheel is vibrated ultrasonically.

JP 2008-23893 A JP 2010-194650 A

  However, since high accuracy is required for the arrangement position of the annular electrode in Patent Document 2, there is a possibility that an electrode contact failure may occur due to an error. In addition, since the electrodes are connected by point contact, if the node region, which is a region where vibration is canceled during processing with ultrasonic vibration, changes, electrode contact failure may occur.

  The present invention has been considered in view of such a problem, and when using a grinding wheel for grinding with ultrasonic vibration mounted on a wheel mount, high precision electrode position accuracy is unnecessary, It is an object of the present invention to prevent electrode contact failure even when a node region changes during ultrasonic vibration machining, and to easily attach and detach a grinding wheel.

  The present invention relates to a grinding apparatus including a chuck table for holding a workpiece and a grinding means for grinding the workpiece held on the chuck table. The grinding means is rotatable in a spindle housing. The accommodated spindle, a wheel mount fixed to the tip of the spindle, and an annular ultrasonic vibrator on the wheel base that is fastened by the wheel mount and screws, and a plurality of grinding wheels are annularly arranged at the free end of the wheel base. A grinding wheel and a drive source for rotationally driving the spindle. A movable electrode for supplying high-frequency power to the annular ultrasonic transducer is disposed on the wheel base of the grinding wheel. Is formed of a material that is attracted by magnetic force, and is connected to a spring member and housed in a case. A fixed electrode having a magnetic force is disposed at a position facing the movable electrode in a state where the grinding wheel is fastened with a screw, and on the outer peripheral side in the radial direction of the grinding wheel with respect to the movable electrode. When fastening to the wheel mount with screws, the movable electrode comes into contact with the fixed electrode by the magnetic force of the fixed electrode stronger than the tensile tension of the spring member, and when the spindle is rotated, it is ground rather than the movable electrode by the centrifugal force that acts on the movable electrode The movable electrode applies contact pressure to the fixed electrode disposed on the outer peripheral side in the radial direction of the wheel.

  In the grinding apparatus according to the present invention, the movable electrode that supplies high-frequency power to the ultrasonic vibrator is disposed on the grinding wheel, and the movable electrode is formed of a material that is attracted by magnetic force and is housed in the case by a spring member. In the wheel mount, a fixed electrode having magnetic force is disposed on the outer peripheral side of the movable electrode, and when the grinding wheel is fastened to the grinding mount with screws, the electrodes are arranged so that each other faces each other. Since the fixed electrodes are in contact with each other, the electrodes can be easily connected to each other, and the movable electrode and the fixed electrode can be easily attached / detached only by attaching / detaching the grinding wheel to / from the wheel mount. Further, since the movable electrode applies a contact pressure to the fixed electrode by centrifugal force in addition to the magnetic force, the movable electrode and the fixed electrode can be more reliably brought into contact even during rotation.

It is a perspective view which shows an example of a grinding device. It is sectional drawing which shows the structure of a part of grinding apparatus roughly. It is a perspective view which shows an example of the wheel mount provided with the fixed electrode. It is a perspective view which shows an example of a grinding wheel. It is sectional drawing which shows roughly the state with which the grinding wheel was mounted | worn to the wheel mount and the fixed electrode and the movable electrode faced each other. It is sectional drawing which shows schematically the state which mounted | wore the grinding wheel with the wheel mount and the fixed electrode and the movable electrode contacted. It is a perspective view which shows the state which grinds a to-be-processed object.

  A grinding apparatus 1 shown in FIG. 1 is an apparatus in which a workpiece held on a chuck table 2 is subjected to grinding by a grinding means 3, and the chuck table 2 is rotatable and is capable of rotating in the front-rear direction. It is movable.

  The grinding means 3 includes a spindle 31 having a vertical axis and rotatably accommodated in a spindle housing 30, a wheel mount 32 fixed to one tip (lower end) of the spindle 31, and a wheel mount 32. And a fixed grinding wheel 33.

  The grinding means 3 is driven by the grinding feed means 4 and can be moved up and down. The grinding feed means 4 includes a ball screw 40 extending in the vertical direction, a pair of guide rails 41 arranged in parallel to the ball screw 40, a motor 42 connected to one end of the ball screw 40 and rotating the ball screw 40 in both forward and reverse directions. And an elevating part 43 having an internal nut (not shown) screwed into the ball screw 40 and having a side part slidably contacting the guide rail 41, and a support part 44 connected to the elevating part 43 and supporting the grinding means 3 When the ball screw 40 is driven by the motor 42 to rotate and the elevating part 43 is guided by the guide rail 41 and moves up and down, the grinding means 3 is also moved up and down.

  As shown in FIG. 2, the spindle 31 is rotatably supported by the spindle housing 30 in a non-contact state.

  The grinding means 3 includes a drive source 35 that rotationally drives the spindle 31. The drive source 35 is an electric motor, and includes a rotor 350 connected to an intermediate portion of the spindle 31 and a stator coil 351 disposed on the outer peripheral side of the rotor 350. The drive source 35 operates by receiving power supply from the power supply means 5.

  The power supply means 5 includes an AC power supply 50, a voltage adjusting means 51 interposed between the stator coil 361 of the AC power supply 50, a frequency adjusting means 52 for adjusting the frequency of the AC power supplied to the stator coil 361, a voltage The control means 53 which controls the adjustment means 51 and the frequency adjustment means 52, and the input means 54 used for input of the amplitude etc. of an ultrasonic vibration are provided.

  The AC power supply 50 is connected to the stator coil 351 of the drive source 35 via the control circuit 55 and the wiring 56, and the rotor 350 and the spindle 31 can be rotated by supplying AC power to the stator coil 351.

  One end of the spindle 31 is a small-diameter tip 310, and the wheel mount 32 is fixed to the small-diameter tip 310.

  A rotary transformer 36 is provided at the other end of the spindle 31. The rotary transformer 36 includes a power receiving unit 360 connected to the upper end of the spindle 31 and a power feeding unit 361 located on the outer peripheral side of the power receiving unit 360. The power receiving unit 360 includes a rotor core 360a connected to the spindle 31 and a power receiving coil 360b wound around the rotor core 360a.

  The power feeding unit 361 includes a stator core 361a disposed on the outer peripheral side of the stator core 360b constituting the power receiving unit 360, and a power feeding coil 361b disposed on the stator core 361a. AC power is supplied to the power supply coil 361b through the wiring 57.

  A conductive wire 37 is connected to the power receiving coil 360 b of the power receiving means 360. The conductive wire 37 passes through a hole 37a formed in the axial direction of the spindle 31 and is connected to the fixed electrode 38 shown in FIG.

  A plurality of fixed electrodes 38 shown in FIG. 3 are fixed (two in the example of FIG. 3) in a state of protruding downward from the lower surface of the wheel mount 32, and each has magnetism.

  As shown in FIG. 3, the wheel mount 32 is formed with a plurality of annular through holes 320 penetrating in the vertical direction. Screws 321 shown in FIG. 2 are inserted into the through holes 320, and grinding shown in FIG. The grinding wheel 33 is fixed to the wheel mount 32 by fastening to the screw hole 33 a of the wheel 33.

  As shown in FIG. 4, the grinding wheel 33 includes a mounting ring 330 fixed to the wheel mount 32, a wheel base 331 integrally formed below the mounting ring 330, and a free end portion on the lower surface of the wheel base 331. It comprises a plurality of grinding wheels 332 fixed in an annular shape.

A circular center hole 331a is formed at the center of the wheel base 331, and an annular ultrasonic transducer 6 formed concentrically with the center hole 331a is provided around the center hole 331a. As the annular ultrasonic transducer 6, barium titanate (BaTiO ₃ ), lead zirconate titanate (Pb (Zi, Ti) O ₃ ), lithium niobate (LiNbO ₃ ), lithium tantalate (LiTaO ₃ ), niobium Sodium potassium acid (K, N) (KnbO ₃ ) or the like can be used.

  In the wheel base 331, a plurality (two in the example of FIG. 3) of electrode connection portions 7 are disposed on the outer peripheral side of the annular ultrasonic transducer 6. Each electrode connection portion 7 includes a conductive wire 70 electrically connected to the annular ultrasonic transducer 6, a fixing plate 71 to which the conductive wire 70 is fixed, and an outer peripheral side of the fixing plate 71. A movable electrode 72 that is electrically connected to 71, a spring member 73 that connects the fixed plate 71 and the movable electrode 72, and a case 74 that accommodates these members. In the case 74, an opening 740 is formed at an end portion on the radially outer side of the grinding wheel 33, and the movable electrode 72 can be projected and retracted through the opening 740 by the expansion and contraction of the spring member 73.

  The movable electrode 72 is made of a material that is attracted by magnetic force, for example, metal. The expansion / contraction direction of the spring member 73 is the radial direction of the grinding wheel 33, and the movable electrode 72 is located on the outer peripheral side in the radial direction with respect to the spring member 73.

  A plurality of slits 330 a are formed in the mounting ring 330 so as to be spaced apart from each other in the circumferential direction. The slit 330 a plays a role of suppressing transmission of ultrasonic vibration to the wheel mount 32.

  As shown in FIG. 5, the mounting ring 330 and the wheel base 331 are connected by an annular connecting portion 333. The electrode connection portion 7 is accommodated in a space 334 surrounded by the bottom surface 331 b of the wheel base 331 and the inner side surface 333 a of the annular coupling portion 333. In FIG. 5, only one electrode connection portion 7 is illustrated, but at least one other electrode connection portion 7 is disposed in the space 334.

  As shown in FIG. 5, when the screw 321 is fastened and the grinding wheel 33 is fixed to the wheel mount 32, the fixed electrode 38 and the movable electrode 72 of the electrode connection portion 7 face each other. The fixed electrode 38 is located on the outer peripheral side in the radial direction of the grinding wheel 33 with respect to the movable electrode 72.

  Then, as shown in FIG. 6, the movable electrode 72 moves outwardly from the opening 740 with the extension of the spring member 73 and moves in a direction approaching the fixed electrode 38 due to the magnetic force of the fixed electrode 38. Connected to. That is, the magnetic force of the fixed electrode 38 is stronger than the tensile tension of the spring member 73, and the electrode connecting portion 7 is attracted and brought into contact with the magnetic force. Thus, since the fixed electrode 38 and the movable electrode 72 are connected only by attaching the grinding wheel 33 to the wheel mount 32, the high frequency power supplied from the power supply means 5 passes through the conductive wire 37 and the fixed electrode 38. Therefore, the movable electrode 72 can supply high-frequency power to the annular ultrasonic transducer 6.

  On the other hand, since the fixed electrode 38 and the electrode connecting portion 7 are connected by magnetic force, when the grinding wheel 33 is removed from the wheel mount 32 by loosening the screw 321, the connection between the fixed electrode 38 and the electrode connecting portion 7 is released. The

  Thus, by attaching the grinding wheel 33 to the wheel mount 32, the fixed electrode 38 and the electrode connecting portion 7 come into contact with each other by magnetic force, and by removing the grinding wheel 33 from the wheel mount 32, the electrode connecting portion 7 becomes the fixed electrode. Therefore, it is not necessary to operate the contact state between the fixed electrode 38 and the movable electrode 72 separately from the attachment / detachment of the grinding wheel 33 to / from the wheel mount 32, and the attachment / detachment of the grinding wheel can be facilitated. In addition, since the fixed electrode 38 and the movable electrode 72 are attracted and contacted by magnetic force, high positional accuracy is not required, and contact failure due to error does not occur.

  Next, the operation of the apparatus when the workpiece (workpiece) W is ground using the grinding apparatus 1 shown in FIG. 1 will be described. The workpiece W is held on the chuck table 2 with the tape T attached to the held surface. Then, the workpiece W is positioned below the grinding means 3 as the chuck table 2 moves rearward.

  Next, while rotating the chuck table 2 at a rotational speed of, for example, about 300 RPM and rotating the spindle 31 to rotate the grinding wheel 33 at a rotational speed of, for example, about 6000 RPM, the grinding feed means 4 lowers the grinding means 3. By doing so, as shown in FIG. 7, grinding is performed by bringing the rotating grinding wheel 332 into contact with the workpiece W. And when the workpiece | work W becomes desired thickness, the grinding means 3 is raised and grinding is complete | finished.

  As shown in FIG. 6, the movable electrode 72 constituting the electrode connecting portion 7 is connected to the spring member 73 and is located on the outer peripheral side of the grinding wheel 33 with respect to the spring member 73. As the grinding wheel 33 rotates, a centrifugal force directed toward the fixed electrode 38 acts on the movable electrode 72. Therefore, in addition to the contact by magnetic force, the movable electrode 72 applies contact pressure to the fixed electrode 38 also by centrifugal force, so that it is possible to more reliably prevent contact failure.

  In addition, since the movable electrode 72 and the fixed electrode 38 are in contact with each other on the surface, highly accurate alignment is unnecessary, and no contact failure occurs even if the node region during ultrasonic vibration processing changes.

  As the ultrasonic transducer, one formed of lead zirconate titanate (PZT) was used. When the grinding wheel 33 provided with the movable electrode 72 is mounted on the wheel mount 32 provided with the fixed electrode 38 and a voltage of 28 kHz and 150 V is applied from the power supply means 5, the grinding wheel 332 is radial in the frequency of 28 kHz. It vibrated with an amplitude of about 10 μm in the (radial direction) and about 10 μm in the thrust direction (axial direction).

  On the other hand, when a conventional grinding wheel was mounted on a wheel mount and a voltage was applied under the same conditions, the grinding wheel vibrated only with an amplitude of about 0.2 μm in the radial direction.

  As the frequency adjusting means 52 shown in FIG. 2, a digital function generator (DF-1905) provided by the NF circuit design block, which can adjust the frequency of the alternating current from DC to 500 kHz, was used.

1: Grinding device 2: Chuck table 3: Grinding means 30: Spindle housing 31: Spindle 32: Wheel mount 320: Through hole 321: Screw 33: Grinding wheel 33a: Screw hole 330: Mounting ring 330a: Slit 331: Wheel base 332 : Grinding wheel 333: annular connecting portion 334: space 35: drive source 350: rotor 351: stator coil 36: rotary transformer 360: power receiving means 360 a: rotor core 360 b: power receiving coil 361: power feeding means 361 a: stator core 361 b: power feeding coil 37: Conductive wire 37a: Hole 38: Fixed electrode 4: Grinding feed means 40: Ball screw 41: Guide rail 42: Motor 43: Lifting part 44: Support part 5: Power supply means 50: AC power supply 51: Voltage adjustment means 52: Frequency adjustment Means 53: System Control means 54: Input means 55: Control circuit 56, 57: Wiring 6: Annular ultrasonic transducer 7: Electrode connecting portion 70: Conductive wire 71: Fixed plate 72: Movable electrode 73: Spring member 74: Case 740: Opening

Claims (1)

A grinding apparatus comprising a chuck table for holding a workpiece and a grinding means for grinding the workpiece held on the chuck table,
The grinding means includes a spindle rotatably accommodated in a spindle housing, a wheel mount fixed to the tip of the spindle, an annular ultrasonic transducer on a wheel base fastened by the wheel mount and the wheel, A grinding wheel in which a plurality of grinding wheels are annularly arranged at the free end of the wheel base, and a drive source for rotationally driving the spindle,
The wheel base of the grinding wheel is provided with a movable electrode that supplies high-frequency power to the annular ultrasonic transducer,
The movable electrode is formed of a material attracted by a magnetic force, is connected to a spring member, and is housed in a case.
The wheel mount is provided with a fixed electrode having a magnetic force at a position facing the movable electrode in a state where the grinding wheel is fastened with a screw and on a radially outer side of the grinding wheel with respect to the movable electrode. And
When the grinding wheel is fastened to the wheel mount with a screw, the movable electrode comes into contact with the fixed electrode by the magnetic force of the fixed electrode stronger than the tensile tension of the spring member,
When the spindle is rotated, the movable electrode applies a contact pressure to the fixed electrode disposed on the outer peripheral side in the radial direction of the grinding wheel with respect to the movable electrode by centrifugal force acting on the movable electrode. A grinding apparatus characterized by that.

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