Grinding device

Abstract

To provide a grinding device that can perform grinding in accordance with a condition of a grinding stone.SOLUTION: A grinding device which grinds a work-piece, is provided with: a chuck table that holds a work-piece; a griding unit having a spindle whose tip part to which a grinding wheel is attached; a controller; a grinding liquid supply unit that supplies the work-piece and the grinding wheel with grinding liquid; and a grinding-load measuring unit that measures grinding-loads in grinding the work-piece with the grinding wheel. The controller adjusts a temperature of grinding liquid that is supplied by the grinding liquid supply unit, on the basis of the grinding loads measured by the grinding-load measuring unit.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a grinding apparatus for grinding a workpiece.

Background Art

[0002] Device chips each having a device are manufactured by dividing a wafer on which a plurality of devices are formed into individual pieces. Further, a plurality of device chips are mounted on a predetermined substrate, and the mounted device chips are covered with a sealing material (mold resin) made of resin, thereby forming a package substrate. By dividing this package substrate into individual pieces, a package device including a plurality of packaged device chips is manufactured. The device chips and the package devices are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] In recent years, with the miniaturization of electronic devices, thinning of device chips and package devices has been demanded. Therefore, a process of grinding and thinning a wafer or a package substrate before division using a grinding apparatus may be performed. The grinding apparatus includes a chuck table for holding a workpiece and a grinding unit for performing grinding on the workpiece, and an annular grinding wheel including a plurality of grinding wheels is mounted on the grinding unit.

[0004] The workpiece is held by the chuck table, and the grinding wheel is brought into contact with the workpiece while rotating the chuck table and the grinding wheel, whereby the workpiece is ground and thinned. Further, during the grinding of the workpiece, a grinding fluid such as pure water is supplied to the workpiece and the grinding wheel. Thereby, the workpiece and the grinding wheel are cooled, and chips generated by the grinding process are removed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The grinding characteristics (amount of material removed, wear on the grinding wheel, processing quality, etc.) when grinding a workpiece with a grinding machine are affected by the temperature of the grinding fluid supplied to the workpiece and the grinding wheel. Therefore, generally, the grinding fluid is supplied under controlled conditions to suppress variations in grinding characteristics. However, during grinding of a workpiece, the condition of the grinding wheel in contact with the workpiece changes over time. Therefore, even if the temperature of the grinding fluid is kept constant, variations in grinding characteristics may occur due to changes in the condition of the grinding wheel.

[0007] This invention has been made in view of the above problems, and aims to provide a grinding apparatus that can perform grinding according to the condition of the grinding wheel. [Means for solving the problem]

[0008] According to one aspect of the present invention, a grinding apparatus for grinding a workpiece comprises a chuck table for holding the workpiece, a grinding unit having a spindle with a grinding wheel mounted at its tip, a controller, a grinding fluid supply unit for supplying grinding fluid to the workpiece and the grinding wheel, and a grinding load measuring unit for measuring the grinding load when the workpiece is ground by the grinding wheel, wherein the controller adjusts the temperature of the grinding fluid supplied from the grinding fluid supply unit based on the grinding load measured by the grinding load measuring unit. The controller increases the temperature of the grinding fluid supplied from the grinding fluid supply unit when the grinding load measured by the grinding load measuring unit increases, and decreases the temperature of the grinding fluid supplied from the grinding fluid supply unit when the grinding load measured by the grinding load measuring unit decreases. A grinding device is provided.

[0010] Preferably, the grinding load measuring unit measures the current value of the motor that rotates the spindle. Also preferably, the grinding load measuring unit measures the load applied to the chuck table or the spindle. [Effects of the Invention]

[0011] In a grinding apparatus according to one aspect of the present invention, the temperature of the grinding fluid is adjusted based on the grinding load when the workpiece is ground by the grinding wheel. This makes it possible to control the wear of the grinding wheel in accordance with changes in the condition of the grinding wheel, thereby improving processing quality while suppressing excessive wear of the grinding wheel. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing a grinding machine. [Figure 2] This is a cross-sectional view showing a chuck table. [Figure 3] This is a side view showing the grinding device. [Figure 4] This is a side view showing a grinding device capable of measuring the load applied to the chuck table. [Figure 5] This is a side view showing a grinding device capable of measuring the load applied to the spindle. [Modes for carrying out the invention]

[0013] Hereinafter, an embodiment of one aspect of the present invention will be described with reference to the attached drawings. First, an example of the configuration of a grinding apparatus according to this embodiment will be described. Figure 1 is a perspective view showing a grinding apparatus 2 for grinding a workpiece 11. In Figure 1, the X-axis direction (first horizontal direction, left-right direction) and the Y-axis direction (second horizontal direction, front-back direction) are perpendicular to each other. Also, the Z-axis direction (processing feed direction, height direction, vertical direction, up-down direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0014] The grinding device 2 includes a base 4 that supports or accommodates each component that makes up the grinding device 2. An opening 4a is provided on the upper side of the front end of the base 4, and a transport unit (transport mechanism) 6 for transporting the workpiece 11 is provided inside the opening 4a. For example, a transport robot equipped with a robot hand (end effector) capable of holding the workpiece 11 is used as the transport unit 6.

[0015] Cassette installation areas 8A and 8B are provided on both sides of the transport unit 6. Cassettes 10A and 10B, capable of accommodating multiple workpieces 11, are placed on the cassette installation areas 8A and 8B, respectively. Cassettes 10A and 10B can accommodate workpieces 11 that are to be processed by the grinding device 2 (workpieces 11 before processing) and workpieces 11 that have been processed by the grinding device 2 (workpieces 11 after processing), respectively.

[0016] For example, the workpiece 11 is a disc-shaped wafer made of a semiconductor material such as single-crystal silicon, and has a surface (first surface) 11a and a back surface (second surface) 11b that are generally parallel to each other. The workpiece 11 is divided into multiple rectangular regions by multiple streets (planned division lines) arranged in a grid pattern so as to intersect each other. Furthermore, devices such as ICs (Integrated Circuits), LSIs (Large Scale Integrations), LEDs (Light Emitting Diodes), and MEMS (Micro Electro Mechanical Systems) devices are formed in each region divided by the streets on the surface 11a side of the workpiece 11.

[0017] Multiple device chips, each containing a device, are manufactured by dividing the workpiece 11 along a street using processing equipment such as a cutting device or a laser processing device. Furthermore, thinned device chips are obtained by grinding the workpiece 11 with a grinding device 2 before or after division.

[0018] However, there are no restrictions on the type, material, size, shape, structure, etc., of the workpiece 11. For example, the workpiece 11 may be a substrate (wafer) made of semiconductors other than silicon (GaAs, InP, GaN, SiC, etc.), glass, ceramics, resin, metal, etc. Furthermore, there are no restrictions on the type, quantity, shape, structure, size, arrangement, etc., of the devices formed on the workpiece 11, and the workpiece 11 does not even need to have devices formed on it.

[0019] Furthermore, the workpiece 11 may be a package substrate such as a CSP (Chip Size Package) substrate or a QFN (Quad Flat Non-leaded package) substrate. For example, the package substrate is formed by encapsulating a plurality of device chips mounted on a predetermined substrate with a resin layer (mold resin). By dividing the package substrate into individual pieces, a plurality of package devices each including a plurality of packaged device chips are manufactured.

[0020] An alignment mechanism 12 is provided diagonally rearward of the opening 4a. The workpieces 11 accommodated in the cassettes 10A and 10B are conveyed to the alignment mechanism 12 by the conveyance unit 6. Then, the alignment mechanism 12 sandwiches the workpiece 11 and arranges it at a predetermined position.

[0021] A conveyance unit (conveyance mechanism, loading arm) 14 for conveying the workpiece 11 is provided at a position adjacent to the alignment mechanism 12. For example, the conveyance unit 14 includes a suction pad that sucks and holds the upper surface side of the workpiece 11. After the conveyance unit 14 holds the workpiece 11 aligned by the alignment mechanism 12 with the suction pad, it rotates the suction pad and conveys the workpiece 11 backward.

[0022] A disk-shaped turntable 16 is provided behind the conveyance unit 14. A rotation drive source (not shown) such as a motor for rotating the turntable 16 around a rotation axis substantially parallel to the Z-axis direction is connected to the turntable 16.

[0023] A plurality of chuck tables (holding tables) 18 for holding the workpiece 11 are provided on the turntable 16. FIG. 1 shows an example in which three chuck tables 18 are arranged at substantially equal intervals (120° intervals) along the circumferential direction of the turntable 16. However, the number of chuck tables 18 is not limited.

[0024] Figure 2 is a cross-sectional view showing the chuck table 18. The chuck table 18 comprises a cylindrical frame (main body) 20 made of metal such as SUS (stainless steel), glass, ceramics, resin, etc. A cylindrical recess 20b is provided in the center of the upper surface 20a of the frame 20.

[0025] A disc-shaped holding member 22 made of a porous material such as porous ceramics is fitted into the recess 20b of the frame 20. The holding member 22 contains numerous pores that communicate from the top surface to the bottom surface of the holding member 22. The top surface of the holding member 22 forms a circular suction surface 22a that sucks the workpiece 11 when the workpiece 11 is held by the chuck table 18.

[0026] The upper surface 20a of the frame 20 and the suction surface 22a of the holding member 22 form a holding surface 18a for holding the workpiece 11. The holding surface 18a (suction surface 22a) is connected to a suction source (not shown), such as an ejector, via pores contained in the holding member 22, a flow path 20c formed inside the frame 20, a valve (not shown), etc.

[0027] The holding surface 18a of the chuck table 18 is formed in a conical shape with the center of the holding surface 18a as its apex, and is slightly inclined with respect to the radial direction of the holding surface 18a. The chuck table 18 is positioned at a slight inclination such that the holding area 18b, which corresponds to a part of the holding surface 18a and extends from the center of the holding surface 18a to its outer edge, is approximately parallel to the horizontal plane. The inclination of the chuck table 18 is adjusted by the inclination adjustment mechanism 70 (see Figure 3), which will be described later.

[0028] A rotational drive source (not shown), such as a motor, is connected to the chuck table 18. The rotational drive source rotates the chuck table 18 around a rotation axis 24. The rotation axis 24 of the chuck table 18 is set along a direction perpendicular to the radial direction of the holding surface 18a, intersecting with the holding surface 18a and passing through the center of the holding surface 18a. In addition, the rotation axis 24 is slightly inclined with respect to the Z-axis direction.

[0029] Note that in Figure 2, the inclination of the holding surface 18a is exaggerated for illustrative purposes, but the actual inclination of the holding surface 18a is small. For example, when the diameter of the holding surface 18a is approximately 290 mm to 310 mm, the height difference between the center of the holding surface 18a and its outer edge (corresponding to the height of the cone) is set to approximately 20 μm to 40 μm.

[0030] The turntable 16 shown in Figure 1 rotates clockwise in a plan view. This positions each chuck table 18 sequentially at the transport position A, the rough grinding position (first grinding position) B, the finish grinding position (second grinding position) C, and back to the transport position A.

[0031] A thickness measuring device 26 is provided near the rough grinding position B and near the finish grinding position C, respectively, to measure the thickness of the workpiece 11 held by the chuck table 18. For example, the thickness measuring device 26 includes a first height measuring device (first height gauge) for measuring the height of the upper surface of the workpiece 11 held by the chuck table 18, and a second height measuring device (second height gauge) for measuring the height of the upper surface of the chuck table 18.

[0032] Columnar support structures 28A and 28B are positioned behind the rough grinding position B and the finish grinding position C, respectively. A moving unit (moving mechanism) 30A is provided on the front side of support structure 28A, and a moving unit (moving mechanism) 30B is provided on the front side of support structure 28B.

[0033] Each of the moving units 30A and 30B is equipped with a pair of guide rails 32 arranged along the Z-axis. A flat moving plate 34 is mounted on the pair of guide rails 32 so as to be slidable along the guide rails 32.

[0034] A nut (not shown) is provided on the rear (back) side of the movable plate 34. A ball screw 36, which is positioned between a pair of guide rails 32 along the Z-axis direction, is screwed into this nut. A pulse motor 38, which rotates the ball screw 36, is connected to the end of the ball screw 36. When the ball screw 36 is rotated by the pulse motor 38, the movable plate 34 moves along the Z-axis direction.

[0035] A grinding unit (rough grinding unit) 40A is mounted on the movable plate 34 of the movable unit 30A to perform rough grinding on the workpiece 11. The grinding unit 40A grinds the workpiece 11, which is held by the chuck table 18 positioned at the rough grinding position B. In addition, a grinding unit (finish grinding unit) 40B is mounted on the movable plate 34 of the movable unit 30B to perform finish grinding on the workpiece 11. The grinding unit 40B grinds the workpiece 11, which is held by the chuck table 18 positioned at the finish grinding position C.

[0036] Each grinding unit 40A and 40B is equipped with a hollow, cylindrical housing 42. The housing 42 is fixed to the front side (surface side) of the movable plate 34. The housing 42 houses a cylindrical spindle 44 (see Figure 3) arranged along the Z-axis direction, with the tip (lower end) of the spindle 44 exposed from the housing 42. A motor 46 for rotating the spindle 44 is connected to the base end (upper end) of the spindle 44, and a disc-shaped wheel mount 48 made of metal or the like is fixed to the tip of the spindle 44.

[0037] A rough grinding wheel (rough grinding wheel) 50A is mounted on the underside of the wheel mount 48 of grinding unit 40A. On the other hand, a finish grinding wheel (finish grinding wheel) 50B is mounted on the underside of the wheel mount 48 of grinding unit 40B. The grinding wheels 50A and 50B are machining tools that are detachable from the wheel mount 48 and grind the workpiece 11, and are fixed to the wheel mount 48 by fasteners such as fastening bolts. As a result, the grinding wheels 50A and 50B are mounted on the tip of the spindle 44.

[0038] As shown in Figure 3, the grinding wheel 50A includes an annular wheel base 52. The wheel base 52 is made of a metal such as aluminum or stainless steel and is formed to be approximately the same diameter as the wheel mount 48. Multiple grinding wheels 54 are fixed to the lower surface of the wheel base 52. For example, the grinding wheels 54 are formed in a rectangular parallelepiped shape and are arranged in an annular pattern at approximately equal intervals along the circumferential direction of the wheel base 52.

[0039] The grinding wheel 54 includes abrasive grains made of diamond, cBN (cubic boron nitride), etc., and a binder (bonding material) such as a metal bond, resin bond, or vitrified bond to fix the abrasive grains. There are no restrictions on the material, shape, structure, size, etc. of the grinding wheel 54, and the number and arrangement of the grinding wheels 54 can also be set arbitrarily.

[0040] When the motor 46 is driven, the spindle 44 and grinding wheel 50A rotate around a rotation axis that is roughly parallel to the Z-axis direction. As a result, each of the multiple grinding wheels 54 rotates along an annular rotation path (trajectory) centered on the rotation axis of the spindle 44 and grinding wheel 50A.

[0041] The grinding wheel 50B (see Figure 1) is constructed in the same manner as the grinding wheel 50A. However, the average particle size of the abrasive grains contained in the grinding wheel 54 of the grinding wheel 50B is smaller than the average particle size of the abrasive grains contained in the grinding wheel 54 of the grinding wheel 50A.

[0042] The moving unit 30A raises and lowers the grinding unit 40A along the Z-axis, thereby bringing the chuck table 18 and grinding wheel 50A, which are positioned at the rough grinding position B, closer together and further apart along the Z-axis. Similarly, the moving unit 30B raises and lowers the grinding unit 40B along the Z-axis, thereby bringing the chuck table 18 and grinding wheel 50B, which are positioned at the finish grinding position C, closer together and further apart along the Z-axis.

[0043] As shown in Figure 1, a transport unit (transport mechanism, unloading arm) 56 for transporting the workpiece 11 is provided at a position adjacent to the transport unit 14 in the X-axis direction. For example, the transport unit 56 is equipped with a suction pad that holds the upper surface of the workpiece 11 by suction. The transport unit 56 holds the workpiece 11, which is held by the chuck table 18 located at transport position A, with the suction pad, and then rotates the suction pad to transport the workpiece 11 forward.

[0044] A cleaning unit (cleaning mechanism, cleaning device) 58 for cleaning the workpiece 11 is provided on the front side of the conveying unit 56. The cleaning unit 58 cleans the workpiece 11 that has been conveyed from the chuck table 18 by the conveying unit 56. For example, the cleaning unit 58 includes a spinner table that holds and rotates the workpiece 11, and a nozzle that supplies a cleaning liquid (such as pure water) to the workpiece 11 held by the spinner table.

[0045] Furthermore, the grinding apparatus 2 includes a controller (control unit, control unit, control device) 60 connected to each component of the grinding apparatus 2 (transport unit 6, alignment mechanism 12, transport unit 14, turntable 16, chuck table 18, thickness measuring instrument 26, moving units 30A, 30B, grinding units 40A, 40B, transport unit 56, cleaning unit 58, etc.). The controller 60 controls the operation of the grinding apparatus 2 by outputting control signals to each component of the grinding apparatus 2.

[0046] For example, the controller 60 is composed of a computer and includes a calculation unit that performs calculations necessary for the operation of the grinding machine 2, and a storage unit that stores various information (data, programs, etc.) used for the operation of the grinding machine 2. The calculation unit includes a processor such as a CPU (Central Processing Unit). The storage unit includes memory such as ROM (Read Only Memory) and RAM (Random Access Memory).

[0047] When processing the workpiece 11 with the grinding machine 2, first, a cassette 10A or cassette 10B containing multiple workpieces 11 is placed on the cassette installation area 8A or cassette installation area 8B. Then, the workpieces 11 are transported from the cassette 10A or cassette 10B to the alignment mechanism 12 by the transport unit 6, and the workpieces 11 are aligned by the alignment mechanism 12. After that, the workpieces 11 are transported by the transport unit 14 to the chuck table 18 located at transport position A, and are held by the chuck table 18.

[0048] Next, the turntable 16 rotates, and the chuck table 18 holding the workpiece 11 is positioned at the rough grinding position B. Then, the workpiece 11 is ground by the grinding wheel 50A mounted on the grinding unit 40A. This performs rough grinding on the workpiece 11.

[0049] Next, the turntable 16 rotates, and the chuck table 18 holding the workpiece 11 is positioned at the finish grinding position C. Then, the workpiece 11 is ground by the grinding wheel 50B mounted on the grinding unit 40B. This completes the finish grinding of the workpiece 11.

[0050] Once grinding of the workpiece 11 is complete, the turntable 16 rotates, and the chuck table 18 holding the workpiece 11 is repositioned to the transport position A. The workpiece 11 is then transported from the chuck table 18 to the washing unit 58 by the transport unit 56, where it is washed. After washing, the workpiece 11 is transported by the transport unit 6 and placed back into cassette 10A or cassette 10B.

[0051] Next, the operation of the grinding device 2 during grinding of the workpiece 11 will be described in detail. Figure 3 is a side view showing the grinding device 2 that grinds the workpiece 11. Note that in Figure 3, for simplification, the holding surface 18a of the chuck table 18 is shown as flat, but the actual holding surface 18a is formed in a conical shape as shown in Figure 2.

[0052] A tilt adjustment mechanism 70 is connected to the chuck table 18 to adjust its tilt. For example, the tilt adjustment mechanism 70 includes a disc-shaped table base 72 that supports the chuck table 18 via bearings (not shown), and one fixed support member 74A and two movable support members 74B that support the table base 72. In Figure 3, only one of the movable support members 74B is shown, and the other movable support member 74B is not shown.

[0053] One fixed support member 74A and two movable support members 74B are arranged at approximately equal intervals (120° intervals) along the circumferential direction of the table base 72. The upper ends of the fixed support member 74A and the upper ends of the movable support members 74B are fixed to the lower surface of the table base 72, respectively.

[0054] The fixed support member 74A is configured so that its upper end is fixed at a predetermined height. On the other hand, the movable support member 74B is configured so that its upper end can move (raise and lower) along the Z-axis direction. By inputting a control signal from the controller 60 to the movable support member 74B, the height position of the upper end of the movable support member 74B can be changed. This adjusts the tilt of the chuck table 18, allowing the holding area 18b (see Figure 2) of the chuck table 18 to be positioned horizontally.

[0055] When grinding the workpiece 11 with the grinding device 2, the workpiece 11 is first held by the holding surface 18a of the chuck table 18. Specifically, the workpiece 11, which has been aligned by the alignment mechanism 12 (see Figure 1), is transported by the transport unit 14 (see Figure 1) and placed on the chuck table 18 located at transport position A.

[0056] For example, the workpiece 11 is placed on the chuck table 18 such that its front surface 11a faces the holding surface 18a and its back surface 11b is exposed upwards. At this time, the workpiece 11 is positioned so that the center of the workpiece 11 and the center of the holding surface 18a coincide, and the entire suction surface 22a (see Figure 2) is covered by the workpiece 11. When the suction force (negative pressure) of the suction source is applied to the holding surface 18a in this state, the workpiece 11 is held in place by the chuck table 18.

[0057] Furthermore, a protective sheet may be attached to the surface 11a side of the workpiece 11 to protect the workpiece 11. This ensures that the surface 11a side (device, etc.) of the workpiece 11 is covered and protected by the protective sheet. The workpiece 11 is then held by the holding surface 18a of the chuck table 18 via the protective sheet.

[0058] For example, a protective sheet may be used that includes a circular film-like substrate and an adhesive layer (glue layer) provided on the substrate. The substrate is made of a resin such as polyolefin, polyvinyl chloride, or polyethylene terephthalate. The adhesive layer is made of an epoxy, acrylic, or rubber-based adhesive. The adhesive layer may also be made of an ultraviolet-curable resin that hardens when exposed to ultraviolet light.

[0059] Next, the turntable 16 (see Figure 1) rotates, and the chuck table 18 holding the workpiece 11 is positioned at the rough grinding position B. This adjusts the positional relationship between the chuck table 18 and the grinding wheel 50A so that the center of the workpiece 11 and the rotation path of the grinding wheel 54 of the grinding wheel 50A coincide.

[0060] Next, while rotating the chuck table 18 and the grinding wheel 50A respectively, the grinding unit 40A is lowered along the Z-axis at a predetermined speed, bringing the holding surface 18a of the chuck table 18 and the grinding wheel 50A relatively close together. The relative movement speed of the chuck table 18 and the grinding wheel 50A in the Z-axis direction at this time corresponds to the machining feed rate. For example, the rotational speed of the chuck table 18 is set to 100 rpm or more and 900 rpm or less, and the rotational speeds of the spindle 44 and the grinding wheel 50A are set to 1000 rpm or more and 3000 rpm or less. The machining feed rate is set to, for example, 1.5 μm / s or more and 5.0 μm / s or less.

[0061] When the rotating grinding wheel 54 contacts the back surface 11b of the workpiece 11, the back surface 11b of the workpiece 11 is ground away. This grinds and thins the workpiece 11. Furthermore, as grinding of the workpiece 11 by the grinding wheel 54 continues, the binder of the grinding wheel 54 wears down, causing the abrasive grains exposed from the binder to fall off, while new abrasive grains embedded inside the binder become exposed. This phenomenon is called self-sharpening, and the grinding capacity of the grinding wheel 54 is maintained by self-sharpening.

[0062] When the workpiece 11 has been ground down to a predetermined thickness, the grinding unit 40A rises, and the grinding wheel 54 is separated from the workpiece 11. This stops the rough grinding of the workpiece 11 by the grinding wheel 50A. Subsequently, the workpiece 11 is ground by the grinding unit 40B (see Figure 1) in the same procedure, and the workpiece 11 is finished by the grinding wheel 50A (see Figure 1).

[0063] During grinding of the workpiece 11, grinding fluid is continuously supplied to the workpiece 11 and the grinding wheels 50A and 50B. This cools the workpiece 11 and the grinding wheel 54, and washes away the debris (grinding chips) generated by the grinding process.

[0064] Specifically, a grinding fluid supply unit 80 is provided near the grinding unit 40A to supply grinding fluid 94 to the workpiece 11 and the grinding wheel 50A. The grinding fluid supply unit 80 is configured to supply grinding fluid 94 at any temperature within a predetermined temperature range.

[0065] For example, the grinding fluid supply unit 80 includes an L-shaped support arm 82 and a nozzle 84 attached to the tip of the support arm 82. The support arm 82 and nozzle 84 are positioned inside the rotation path of the multiple grinding wheels 54 provided by the grinding wheel 50A. Therefore, even when the grinding wheel 50A is raised or lowered, the grinding wheels 54 do not interfere with the support arm 82 and nozzle 84.

[0066] The nozzle 84 is connected to the grinding fluid supply passage 86 via a flow path (not shown) provided inside the support arm 82. The grinding fluid supply passage 86 is connected to the grinding fluid source 90A via the grinding fluid supply passage 88A, and to the grinding fluid source 90B via the grinding fluid supply passage 88B. The grinding fluid supply passages 86, 88A, and 88B are constructed using piping such as tubes and pipes.

[0067] Grinding fluid supply sources 90A and 90B each supply a liquid (grinding fluid) such as pure water to grinding fluid supply passages 88A and 88B. For example, grinding fluid supply sources 90A and 90B are equipped with a tank for storing the grinding fluid and a pump for dispensing the grinding fluid from the tank. Alternatively, grinding fluid supply sources 90A and 90B may be factory equipment (liquid supply equipment) installed in the factory where the grinding device 2 is installed.

[0068] Furthermore, the temperature of the grinding fluid supplied from the grinding fluid supply source 90A to the grinding fluid supply passage 88A is higher than the temperature of the grinding fluid supplied from the grinding fluid supply source 90B to the grinding fluid supply passage 88B. In other words, the grinding fluid supply source 90A corresponds to a high-temperature grinding fluid supply source that supplies high-temperature grinding fluid, and the grinding fluid supply passage 88A corresponds to a high-temperature grinding fluid supply passage that supplies high-temperature grinding fluid. Also, the grinding fluid supply source 90B corresponds to a low-temperature grinding fluid supply source that supplies low-temperature grinding fluid, and the grinding fluid supply passage 88B corresponds to a low-temperature grinding fluid supply passage that supplies low-temperature grinding fluid.

[0069] The temperature of the grinding fluid supplied from the grinding fluid sources 90A and 90B is set according to the temperature range of the grinding fluid 94 to be supplied to the workpiece 11 and the grinding wheel 50A during grinding of the workpiece 11. For example, grinding fluid source 90A supplies grinding fluid at 30°C or higher, and grinding fluid source 90B supplies grinding fluid at 15°C or lower.

[0070] Valve 92A is connected to the grinding fluid supply passage 88A to control the flow rate of high-temperature grinding fluid supplied from the grinding fluid supply source 90A to the grinding fluid supply passage 86. Valve 92B is connected to the grinding fluid supply passage 88B to control the flow rate of low-temperature grinding fluid supplied from the grinding fluid supply source 90B to the grinding fluid supply passage 86. Valves 92A and 92B are, for example, electromagnetic valves and are connected to the controller 60.

[0071] The controller 60 controls the open / closed state (open / closed time, opening degree, etc.) of valves 92A and 92B by outputting control signals to them. The high-temperature grinding fluid supplied from grinding fluid supply source 90A and the low-temperature grinding fluid supplied from grinding fluid supply source 90B are mixed in the grinding fluid supply passage 86 and supplied to the nozzle 84. At this time, by adjusting the flow rates of the high-temperature grinding fluid and the low-temperature grinding fluid, the temperature of the grinding fluid 94 can be arbitrarily set within a temperature range that is above the temperature of the low-temperature grinding fluid and below the temperature of the high-temperature grinding fluid. In this way, by mixing the high-temperature and low-temperature grinding fluids in a predetermined ratio, grinding fluid 94 at the desired temperature can be quickly generated.

[0072] As described above, when the workpiece 11 is rough-ground by the grinding wheel 50A, the desired grinding fluid 94 is supplied from the grinding fluid supply unit 80 to the workpiece 11 and the grinding wheel 50A. The grinding fluid supply unit 80 is also installed near the grinding unit 40B (see Figure 1). When the workpiece 11 is finish-ground by the grinding wheel 50B (see Figure 1), the grinding fluid supply unit 80 also supplies the workpiece 11 and the grinding wheel 50B with grinding fluid 94 at the desired temperature.

[0073] Here, during the grinding of the workpiece 11, the condition of the grinding wheel 54 is not constant but changes over time. For example, the shape and protrusion amount of abrasive grains contained in the grinding wheel 54, the amount of grinding debris adhering to the grinding wheel 54, and the frequency of abrasive grain detachment due to wear of the binder all fluctuate during the grinding of the workpiece 11. When the condition of the grinding wheel 54 changes, the pressure (grinding load) applied to the workpiece 11 and the grinding wheel 54 during grinding also changes, resulting in variations in grinding characteristics.

[0074] Furthermore, it has been confirmed that the ease with which the grinding wheel 54 wears down depends on the temperature of the grinding fluid 94. Specifically, when the temperature of the grinding fluid 94 is high, the wear of the grinding wheel 54 is accelerated, and the self-sharpening of the grinding wheel 54 and the discharge of grinding chips become more likely. This promotes the recovery of the grinding capacity of the grinding wheel 54 and improves processing quality. On the other hand, when the temperature of the grinding fluid 94 is low, the wear of the grinding wheel 54 is suppressed, and the life of the grinding wheel 54 is extended.

[0075] Therefore, the grinding apparatus 2 according to this embodiment adjusts the temperature of the grinding fluid 94 based on the grinding load. This makes it possible to control the wear of the grinding wheel 54 in accordance with changes in the condition of the grinding wheel 54, and to improve processing quality while suppressing excessive wear of the grinding wheel 54.

[0076] The temperature of the grinding fluid 94 is controlled by the controller 60. The controller 60 increases or decreases the temperature of the grinding fluid 94 supplied from the grinding fluid supply unit 80 to the workpiece 11 and the grinding wheels 50A and 50B based on the grinding load when the workpiece 11 is being ground by the grinding wheels 50A and 50B. Figure 3 shows a block diagram illustrating the functional configuration of the controller 60.

[0077] The controller 60 includes a temperature determination unit 60a that determines the temperature of the grinding fluid 94, and a temperature information storage unit 60b that stores information (data, programs, etc.) used to determine the temperature by the temperature determination unit 60a. The temperature determination unit 60a determines the temperature of the grinding fluid 94 based on a value corresponding to the grinding load input from the grinding load measuring unit provided in the grinding device 2 and the information stored in the temperature information storage unit 60b.

[0078] For example, the temperature determination unit 60a is connected to the motor 46 that rotates the spindle 44 of the grinding unit 40A. During grinding of the workpiece 11, the motor 46 itself constantly measures the current value of the motor 46, and the current value of the motor 46 is sequentially input from the motor 46 to the temperature determination unit 60a.

[0079] The current value of motor 46 corresponds to the torque of motor 46 required to maintain the rotational speed of spindle 44, wheel mount 48, and grinding wheel 50A at a predetermined value. In other words, the current value of motor 46 corresponds to the force (grinding load) acting on the workpiece 11 and grinding wheel 54 during grinding. Therefore, motor 46 functions as a grinding load measuring unit to measure the grinding load.

[0080] Specifically, when the grinding wheel 50A is pressed firmly against the workpiece 11, a large grinding load is applied to both the workpiece 11 and the grinding wheel 50A. As a result, the torque required to maintain the rotation of the spindle 44 increases, and the current value of the motor 46 also increases. Therefore, the grinding load can be monitored by measuring the current value of the motor 46 during the grinding of the workpiece 11.

[0081] The temperature information storage unit 60b stores the temperature of the grinding fluid 94 corresponding to the grinding load. For example, correspondence information (graphs, tables, etc.) showing the relationship between the current value of the motor 46 and the appropriate temperature of the grinding fluid 94 for that current value is stored in the temperature information storage unit 60b. When the current value of the motor 46 is input to the temperature determination unit 60a, the temperature determination unit 60a reads the correspondence information from the temperature information storage unit 60b and determines the appropriate temperature of the grinding fluid 94 by applying the input current value of the motor 46 to the correspondence information.

[0082] The controller 60 also includes a temperature control unit 60c that adjusts the temperature of the grinding fluid 94 supplied from the grinding fluid supply unit 80. When the temperature determination unit 60a determines the temperature of the grinding fluid 94, a signal (temperature specification signal) specifying the temperature of the grinding fluid 94 is input from the temperature determination unit 60a to the temperature control unit 60c.

[0083] When a temperature specification signal is input to the temperature control unit 60c, the temperature control unit 60c outputs a control signal to the valves 92A and 92B of the grinding fluid supply unit 80, controlling the open / closed state (open / closed time, opening degree, etc.) of the valves 92A and 92B so that grinding fluid 94 at the specified temperature is produced. As a result, high-temperature grinding fluid and low-temperature grinding fluid flow from the grinding fluid supply sources 90A and 90B through the valves 92A and 92B into the grinding fluid supply passage 86 at a predetermined flow rate and are mixed in the grinding fluid supply passage 86. Consequently, grinding fluid 94 at the temperature determined by the temperature determination unit 60a is supplied from the nozzle 84 toward the workpiece 11 and the grinding wheel 50A.

[0084] For example, the correspondence information stored in the temperature information storage unit 60b is set such that the higher the current value (grinding load) of the motor 46, the higher the temperature of the grinding fluid 94, and the lower the current value (grinding load) of the motor 46, the lower the temperature of the grinding fluid 94. In this case, if the current value (grinding load) of the motor 46 increases during grinding of the workpiece 11, the controller 60 increases the temperature of the grinding fluid 94 supplied from the grinding fluid supply unit 80. On the other hand, if the current value (grinding load) of the motor 46 decreases during grinding of the workpiece 11, the controller 60 decreases the temperature of the grinding fluid 94 supplied from the grinding fluid supply unit 80.

[0085] As described above, by controlling the temperature of the grinding fluid 94, if the condition of the grinding wheel 54 is poor and the grinding load is high, the wear of the grinding wheel 54 is accelerated and the grinding capacity of the grinding wheel 54 is restored. If the condition of the grinding wheel 54 is good and the grinding load is low, the wear of the grinding wheel 54 is suppressed and the life of the grinding wheel 54 is extended. In other words, the workpiece 11 can be ground while switching between grinding that is advantageous for restoring the grinding capacity of the grinding wheel 54 and grinding that is advantageous for extending the life of the grinding wheel 54, depending on the condition of the grinding wheel 54.

[0086] Although Figure 3 illustrates the case where the motor 46 functions as a grinding load measuring unit to measure the grinding load, the grinding load may also be measured by components other than the motor 46. Figure 4 is a side view showing a grinding apparatus 2 capable of measuring the load applied to the chuck table 18.

[0087] The grinding apparatus 2 shown in Figure 4 is equipped with multiple load measuring devices (load cells) 100 for measuring the load applied to the chuck table 18. For example, the load measuring devices 100 are installed on the table base 72 so as to overlap with the fixed support member 74A or the movable support member 74B, and measure the load applied to the chuck table 18 in the Z-axis direction. During grinding of the workpiece 11, the load applied to the chuck table 18 is constantly measured by the multiple load measuring devices 100.

[0088] The load value measured by the load measuring device 100 corresponds to the grinding load acting on the workpiece 11 and the grinding wheel 54 during grinding. Therefore, the load measuring device 100 functions as a grinding load measuring unit that measures the grinding load. The load measured by the load measuring device 100 is then input to the temperature determination unit 60a.

[0089] The temperature information storage unit 60b stores correspondence information (graphs, tables, etc.) that shows the relationship between the load applied to the chuck table 18 and the appropriate temperature of the grinding fluid 94 for that load. The temperature determination unit 60a then determines the appropriate temperature of the grinding fluid 94 by applying the load values ​​(sum of values, average values, etc.) measured by multiple load measuring devices 100 to the correspondence information stored in the temperature information storage unit 60b.

[0090] Subsequently, a temperature specification signal is input from the temperature determination unit 60a to the temperature control unit 60c, and the temperature control unit 60c controls valves 92A and 92B so that the grinding fluid 94 is supplied from the grinding fluid supply unit 80 at the temperature determined by the temperature determination unit 60a.

[0091] Furthermore, the grinding load may be measured based on the load applied to components other than the chuck table 18. Figure 5 is a side view showing a grinding apparatus 2 capable of measuring the load applied to the spindle 44.

[0092] The grinding apparatus 2 shown in Figure 5 is equipped with a load measuring device (load cell) 102 for measuring the load applied to the spindle 44. For example, the load measuring device 102 is connected to the base end (upper end) of the spindle 44 and measures the load applied to the spindle 44 in the Z-axis direction. During grinding of the workpiece 11, the load applied to the spindle 44 is constantly measured by the load measuring device 102.

[0093] The load value measured by the load measuring device 102 corresponds to the grinding load acting on the workpiece 11 and the grinding wheel 54 during grinding. Therefore, the load measuring device 102 functions as a grinding load measuring unit that measures the grinding load. The load measured by the load measuring device 102 is then input to the temperature determination unit 60a.

[0094] The temperature information storage unit 60b stores correspondence information (graphs, tables, etc.) that shows the relationship between the load applied to the spindle 44 and the appropriate temperature of the grinding fluid 94 for that load. The temperature determination unit 60a then determines the appropriate temperature of the grinding fluid 94 by applying the load value measured by the load measuring instrument 102 to the correspondence information stored in the temperature information storage unit 60b.

[0095] Subsequently, a temperature specification signal is input from the temperature determination unit 60a to the temperature control unit 60c, and the temperature control unit 60c controls valves 92A and 92B so that the grinding fluid 94 is supplied from the grinding fluid supply unit 80 at the temperature determined by the temperature determination unit 60a.

[0096] As described above, in the grinding apparatus 2 according to this embodiment, the temperature of the grinding fluid 94 is adjusted based on the grinding load when the workpiece 11 is ground by the grinding wheels 50A and 50B. This makes it possible to control the wear of the grinding wheel 54 in accordance with changes in the condition of the grinding wheel 54, and to improve processing quality while suppressing excessive wear of the grinding wheel 54.

[0097] In the above embodiment, a configuration was described in which the temperature of the grinding fluid 94 is adjusted by mixing high-temperature grinding fluid supplied from grinding fluid supply source 90A with low-temperature grinding fluid supplied from grinding fluid supply source 90B (see Figures 3 to 5). However, there are no limitations on the method of adjusting the temperature of the grinding fluid 94. For example, the grinding fluid supply unit 80 may adjust the temperature of the grinding fluid 94 using a heater.

[0098] Specifically, the grinding fluid supply unit 80 may include a grinding fluid supply source, a heater for heating the grinding fluid 94 supplied from the grinding fluid supply source, and a valve for controlling the flow rate of the grinding fluid 94 supplied from the grinding fluid supply source to the heater. In this case, the output of the heater is controlled by a control signal input from the temperature control unit 60c to the heater, thereby adjusting the temperature of the grinding fluid 94. The grinding fluid 94, heated to the desired temperature, is then supplied from the nozzle 84 to the workpiece 11 and the grinding wheels 50A and 50B.

[0099] Furthermore, the structures, methods, etc., according to the above embodiments can be modified as appropriate without departing from the scope of the objectives of the present invention. [Explanation of Symbols]

[0100] 11 Workpiece 11a Surface (first side) 11b Back side (2nd side) 2. Grinding device 4 base 4a aperture 6. Transport Unit (Transport Mechanism) 8A, 8B Cassette installation area 10A, 10B Cassette 12. Alignment mechanism 14. Transport Unit (Transport Mechanism, Loading Arm) 16 Turntables 18. Chuck table (holding table) 18a Holding surface 18b Holding area 20 Frame (main body) 20a top surface 20b recess 20c flow path 22 Retaining member 22a Suction surface 24 rotation axes 26 Thickness measuring instrument 28A,28B Support structure 30A, 30B Mobile Unit (Mobile Mechanism) 32 Guide Rails 34 Mobile Plate 36 Ball screw 38 Pulse motor 40A Grinding Unit (Coarse Grinding Unit) 40B Grinding Unit (Finishing Grinding Unit) 42 Housing 44 spindles 46. ​​Motor (Grinding load detection unit) 48 Wheel Mount 50A Grinding Wheel (Coarse Grinding Wheel) 50B Grinding Wheel (Finishing Grinding Wheel) 52 Wheel base 54 Grinding Wheels 56. Transport Unit (Transport Mechanism, Unloading Arm) 58. Cleaning unit (cleaning mechanism, cleaning device) 60 Controllers (control units, control units, control devices) 60a Temperature determination unit 60b Temperature information storage section 60c temperature control section 70 Tilt adjustment mechanism 72 Table Base 74A Fixed support member 74B Movable support member 80. Grinding fluid supply unit 82 Support Arm 84 nozzles 86 Grinding fluid supply channel 88A, 88B Grinding fluid supply channel 90A, 90B Grinding fluid supply source 92A, 92B valves 94 Grinding fluid 100 Load measuring devices (load cells) 102 Load measuring device (load cell)

Claims

1. A grinding device for grinding a workpiece, A chuck table for holding the workpiece, A grinding unit having a spindle with a grinding wheel attached to its tip, Controller and A grinding fluid supply unit that supplies grinding fluid to the workpiece and the grinding wheel, The system includes a grinding load measuring unit that measures the grinding load when the workpiece is ground by the grinding wheel, The controller adjusts the temperature of the grinding fluid supplied from the grinding fluid supply unit based on the grinding load measured by the grinding load measuring unit. The controller is characterized in that when the grinding load measured by the grinding load measuring unit increases, it increases the temperature of the grinding fluid supplied from the grinding fluid supply unit, and when the grinding load measured by the grinding load measuring unit decreases, it decreases the temperature of the grinding fluid supplied from the grinding fluid supply unit.

2. The grinding apparatus according to claim 1, characterized in that the grinding load measuring unit measures the current value of the motor that rotates the spindle.

3. The grinding apparatus according to claim 1, characterized in that the grinding load measuring unit measures the load applied to the chuck table or the spindle.

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