JP2020146779A - Grinding device - Google Patents

Abstract

To detect an abnormality occurring in grinding processing with high accuracy.SOLUTION: A grinding device 1 comprises: a first grinding/feeding part 46 that grinds a work-piece W at a first grinding/feeding speed so that the work-piece has a first thickness thicker than a finish thickness; a second grinding/feeding part 47 that grinds the work-piece W having the first thickness to the finish thickness at a second grinding/feeding speed slower than the first grinding/feeding speed; an upper limit value setting part 80 that sets an upper limit value of a load value applied to a grinding stone 340 for each grinding/feeding speed, when grinding the work-piece W at respective grinding/feeding speed in stages; and a recognizing part 81 that recognizes that the load value measured during grinding surpasses the upper limit value. The grinding device measures the load values applied to the grinding stone 340 respectively when grinding the work-piece W at respective grinding/feeding speed, monitors whether the values surpass the upper limit value or not, and detects an abnormality occurring in grinding processing.SELECTED DRAWING: Figure 1

Description

The present invention relates to a grinding device.

A grinding device that grinds a work piece with a grinding wheel grinds the work piece to a predetermined thickness, so while measuring the thickness, it grinds to a thickness slightly thicker than the finish thickness at a high grinding feed rate, and then grinds. Grinding is performed by slowing down the feed rate to a set finish thickness (Patent Document 1, Patent Document 2, and Patent Document 3). By grinding at such a slow grinding feed rate, the load of pressing the grinding wheel against the workpiece is reduced and the machine strain is reduced, so that the workpiece is finished to a uniform thickness.

In addition, the upper limit (threshold) of the load value when the grinding wheel pushes the workpiece in advance for the purpose of preventing the grinding wheel from becoming clogged or crushed and unable to grind normally during the grinding process. Is set, and an alarm is issued when the load value detected by the load value detecting means exceeds the upper limit value during grinding.

Japanese Unexamined Patent Publication No. 2012-151409 Japanese Unexamined Patent Publication No. 2013-226625 Japanese Unexamined Patent Publication No. 2014-024145

As described above, when the upper limit of the load value set regardless of the grinding feed rate is exceeded by the load value applied to the grinding wheel measured during the grinding process, this is recognized. ing. However, the load values for the fast grinding feed rate and the slow grinding feed rate in the grinding process are different, and by setting only one upper limit value, normal grinding of the workpiece can be performed. There is a problem that it is insufficient.
Therefore, the grinding device has a problem to be solved that it monitors the load current value of the spindle motor according to each grinding feed speed and detects that an abnormality has occurred in the grinding process.

The present invention includes a holding means for holding a work piece and a grinding means for grinding a work piece held by the holding means by rotating a spindle equipped with a grinding wheel in which a grinding wheel is arranged in an annular shape. , The grinding feed means for moving the holding means and the grinding means in the relative approaching and separating directions, the thickness measuring means for measuring the thickness of the workpiece, and the grinding grindstone were held on the holding surface. A grinding apparatus including a load value detecting means for detecting a load value when the grinding wheel pushes the workpiece by moving the grinding tool in a direction approaching the workpiece, and a control means, wherein the grinding feed means. Is a first grinding feed portion that grinds the workpiece to a first thickness that is thicker than the finish thickness preset at the first grinding feed speed, and a finish thickness at a second grinding feed speed that is slower than the first grinding feed speed. It is equipped with a second grinding feed unit that grinds the workpiece up to, and the control means is used when grinding at the first grinding feed speed and based on the measurement results measured in the past grinding process, and the second grinding feed. With the upper limit value setting unit that sets the upper limit value of the load value detected by the load value detecting means for each grinding feed speed when grinding at a speed, the first grinding feed speed and the second grinding feed speed. It is a grinding device including a recognition unit that recognizes that the load value detected by the load value detecting means exceeds the respective upper limit values during grinding.
Further, in the present invention, a holding means for holding a work piece and a spindle equipped with a grinding wheel in which a grinding wheel is arranged in an annular shape are rotated to grind the work piece held by the holding means with the grinding wheel. Means, a grinding feed means for moving the holding means and the grinding means in relative approaches and separation directions, and a top surface height measuring means for measuring the top surface height of the workpiece held by the holding means. A load value detecting means, a control means, and a load value detecting means for detecting a load value when the grinding wheel moves in a direction of approaching the workpiece held by the holding means and the grinding wheel pushes the workpiece. The grinding feed means measures the height of the upper surface, and at the first grinding feed speed until the upper surface reaches the height of the upper surface lowered by the preset first grinding amount. From the first grinding feed rate, while measuring the height of the first grinding feed section that grinds the work piece and the top surface, until the surface to be ground reaches the finish height lowered by the preset second grinding amount. It is provided with a second grinding feed unit that grinds the workpiece at a slow second grinding feed speed, and the control means grinds at the first grinding feed speed based on the measurement results measured in the past grinding process. An upper limit value setting unit that sets an upper limit value of a load value detected by the load value detecting means for each grinding feed speed when grinding at the time and at the second grinding feed speed, and the first grinding feed speed and A grinding device including a recognition unit that recognizes that the load value detected by the load value detecting means exceeds the respective upper limit values during grinding at the second grinding feed speed.

The control means provided in the above-mentioned grinding device is based on the measurement results set in the past grinding process, and has a feed rate when grinding at the first grinding feed rate and when grinding at the second grinding feed rate. On the other hand, the load value is set when the lower limit value setting unit for setting the lower limit value of the load value detected by the load value detecting means and the first grinding feed speed and the second grinding feed speed are used for grinding. It is preferable to include a second recognition unit that recognizes that the load value detected by the detecting means exceeds the respective lower limit values.

In the present invention, in order to monitor the load value applied to the grinding wheel in relation to the upper limit value of each grinding feed rate between the first grinding feed rate and the second grinding feed rate during the grinding process, the work piece and the work piece are used. It is possible to prevent an unreasonable load from being applied to the grinding wheel. Further, the upper limit of the load value when the grinding feed rate is the second grinding feed rate can be set to a value lower than the conventional value, and it becomes possible to detect that a grinding defect has occurred.

Further, by setting the lower limit value of the load value, it is possible to detect that an abnormality such as chipping of the grindstone or abnormal wear has occurred in the grinding wheel.

It is a perspective view which showed the whole of the grinding apparatus. It is a side view which shows the state of grinding a work piece. (A) is a graph showing the load value when grinding the workpiece at each of the first grinding feed speed and the second grinding feed speed, and (b) is shown in (a). It is a graph in which the upper limit value of the load value is further drawn on the time characteristic graph of the shown load value, and (c) is the graph in which the lower limit value of a load value is further drawn.

1 Configuration of Grinding Device The grinding device 1 shown in FIG. 1 is a grinding device that grinds a workpiece W such as a semiconductor wafer held by the holding means 2 by using the grinding means 3. Hereinafter, the configuration of the grinding device 1 will be described.

The grinding device 1 is provided with a control means 8 having a CPU or the like that electrically controls various mechanisms provided in the grinding device 1. Various mechanisms of the grinding device 1 are connected to a power source (not shown), and operate using the electric power supplied from the power source as a power source.

As shown in FIG. 1, the grinding apparatus 1 is provided with a base 10 extending in the Y-axis direction and a column 11 standing on the base 10 on the + Y direction side.

As shown in FIG. 1, a holding means 2 is provided on the base 10 of the grinding device 1. The holding means 2 is a disk-shaped table for holding the workpiece W, and includes, for example, a suction portion 20 having a holding surface 20a and a frame body 21 surrounding the suction portion 20. Further, the holding means 2 is connected to the suction source 23 via the suction path 22. For example, as shown in FIGS. 1 and 2, a tape T for the purpose of protecting the lower surface Wb of the workpiece W holds the workpiece W attached to the lower surface Wb of the workpiece W on the holding surface 20a. The workpiece W can be suction-held on the holding surface 20a by transmitting the suction force exerted by the suction source 23 to the holding surface 20a through the suction path 22 in the state of being placed on the holding surface 20a.
Further, the holding means 2 is provided with a rotating means 24 for rotating the holding means 2 around a rotating shaft 25 in the Z-axis direction.
In addition, a cover 12 is arranged around the holding means 2, and a bellows 13 is stretchably connected to the cover 12. The cover 12 and the holding means 2 are driven by a moving means in the Y-axis direction (not shown) arranged inside the base 10 when grinding the workpiece W, and are integrated in the Y-axis direction. Move back and forth to. At this time, the bellows 13 expands and contracts as the cover 12 moves in the Y-axis direction.

Further, as shown in FIG. 1, a grinding means 3 and a grinding feeding means 4 are provided on the side surface of the column 11 on the −Y direction side.
As shown in FIGS. 1 and 2, the grinding means 3 includes a spindle 30 having a rotating shaft 35 in the Z-axis direction, a spindle motor 32 for rotationally driving the spindle 30 around the rotating shaft 35, and rotating the spindle 30. A housing 31 that supports it is provided. The housing 31 is composed of, for example, a small diameter portion 310 and a large diameter portion 311 as shown in FIG. A mount 33 is connected to the lower surface 31a of the housing 31, and a grinding wheel 34 is detachably arranged at the lower end of the mount 33. The grinding wheel 34 is composed of a base 341 and a plurality of rectangular parallelepiped-shaped grinding wheels 340 arranged in an annular shape on the lower surface of the base 341. The grinding wheel 340 is formed of, for example, diamond abrasive grains fixed by a resin bond, a metal bond, or the like, and its lower surface 340a is a grinding surface for grinding the workpiece W.

The grinding feed means 4 includes a ball screw 40 having a rotation shaft 45 in the Z-axis direction, a pair of guide rails 41 arranged parallel to the ball screw 40, and a ball screw 40 connected to the upper end of the ball screw 40. It includes a Z-axis motor 42 that rotates around 45, and an elevating plate 43 in which an internal nut is screwed into a ball screw 40 and a side portion is in sliding contact with a guide rail 41. Further, a holder 44 for holding the housing 31 is connected to the elevating plate 43.
As shown in FIGS. 1 and 2, the holder 44 has, for example, a bottomed cylinder shape, and the bottom surface thereof has an annular shape in which a hole 441d is formed. The bottomed cylinder of the holder 44 is separated into a side plate 440 and a bottom plate 441, for example, as shown in FIG.
As shown in FIG. 2, the bottom plate 441 of the holder 44 and the large diameter portion 311 of the housing 31 are connected so that the lower surface 311b of the large diameter portion 311 of the housing 31 and the upper surface 441a of the bottom plate 441 of the holder 44 are in contact with each other. This allows the housing 31 to be held in the holder 44. At this time, the lower portion of the small diameter portion 310 of the housing 31 penetrates the hole 441d.
The side plate 440 and the bottom plate 441 of the holder 44 do not have to be separated from each other.

When the ball screw 40 is driven by the Z-axis motor 42 and rotates around the rotating shaft 45, the elevating plate 43 is guided by the guide rail 41 to move up and down in the Z-axis direction and is held by the holder 44. The grinding means 3 is configured to move up and down in the Z-axis direction. By driving the grinding means 3 using the grinding feed means 4, the grinding wheel 340 can be brought closer to and separated from the workpiece W held by the holding means 2.

Further, the grinding feed means 4 is provided with a first grinding feed portion 46 and a second grinding feed portion 47. The first grinding feed unit 46 has a function of lowering the grinding means 3 in the −Z direction at the first grinding feed speed, and the second grinding feed unit 47 has a second grinding that is slower than the first grinding feed speed. It has a function of lowering the grinding means 3 in the −Z direction at a feed rate.

As shown in FIG. 2, three load value detecting means 6 are formed in the annular gap between the side plate 440 and the bottom plate 441 of the holder 44 so as to be sandwiched between the side plate 440 and the bottom plate 441 from above and below. It is arranged at intervals.
The load value detecting means 6 includes a piezoelectric element (not shown), and when a compressive force is applied to the piezoelectric element during grinding, a voltage corresponding to the force is generated. The load value detecting means 6 can measure the load value based on the value of the generated voltage.
However, as described above, it is conceivable that the side plate 440 of the holder 44 and the bottom plate 441 are not separated from each other. In such a case, the load value detecting means 6 uses the large diameter portion 311 of the housing 31 and the bottom plate of the holder 44. It will be arranged between the 441 and the 441.
Then, the load value detecting means 6 is attached in a state where a compressing force is applied in advance, and the piezoelectric element generates a voltage corresponding to the force applied by the force stretched by the grinding load. That is, it is possible to detect a grinding load equal to or greater than the total weight of the spindle 30, the spindle motor 32, the mount 33, and the grinding wheel 34.

The control means 8 is used to grind the workpiece W by lowering the grinding means 3 in the −Z direction at the first grinding feed speed based on the load value measured in the past grinding process. Upper limit value setting unit for setting the upper limit value of the load value and the upper limit value of the load value when the grinding means 3 is similarly lowered in the −Z direction at the second grinding feed speed to grind the workpiece W. 80 is provided. Further, in the control means 8, the load value measured by the load value detecting means 6 when grinding is performed at the first grinding feed rate or the second grinding feed rate is set by the upper limit value setting unit 80. A recognition unit 81 is provided to recognize that the upper limit value is exceeded.

Similarly, the control means 8 grinds the workpiece W by lowering the grinding means 3 in the −Z direction at the first grinding feed speed based on the measurement result of the load value measured in the past grinding process. The lower limit of the load value at the time of machining and the lower limit of the load value at the time of grinding the workpiece W by lowering the grinding means 3 in the −Z direction at the second grinding feed speed are set respectively. A lower limit value setting unit 82 is provided. Further, the load value measured by the load value detecting means 6 is less than the lower limit value set by the lower limit value setting unit 82 during grinding at the first grinding feed rate or the second grinding feed rate. A second recognition unit 83 for recognizing the above is provided.

As shown in FIG. 1, a thickness measuring means 5 including a wafer upper surface height gauge 50, a holding surface height gauge 51, and a calculating means 52 is arranged on the base 10 of the grinding apparatus 1. During the grinding process, the thickness measuring means 5 brings the wafer upper surface height gauge 50 into contact with the upper surface Wa of the workpiece W and the holding surface height gauge 51 with the holding surface 20a of the holding means 2. The height of the upper surface Wa of the W and the holding surface 20a of the holding means 2 is measured, and the thickness of the workpiece W can be calculated by the calculating means 52 based on the difference between the measured heights.

2 Operation of Grinding Device The operation of the grinding device 1 when grinding the workpiece W using the grinding device 1 having the above configuration will be described with reference to FIGS. 1 to 3.

Before performing the grinding process, the workpiece W is ground at the first grinding feed rate and the second grinding feed rate based on the load value measured in advance by using the load value detecting means 6 in the past grinding process. When the upper limit value of the load value measured by the load value detecting means 6 at the time of processing is set in the upper limit value setting unit 80 and the workpiece W is ground at the first grinding feed speed and the second grinding feed speed. The lower limit value of the load value measured by the load value detecting means 6 is set in the lower limit value setting unit 82.

As a method of setting the upper limit value and the lower limit value, for example, the measurement data of the load value when 25 workpieces W are ground are arranged in the order of size, and the range set in advance from the median value of the measurement data. The largest value of the measurement data included in (for example, statistical interquartile range, etc.) is set as the upper limit value, and the smallest value is set as the lower limit value. Thereby, the upper limit value and the lower limit value can be set from the useful measurement data excluding the data greatly deviating from the median value.

After setting the upper limit value and the lower limit value as described above, the grinding process is started. First, as shown in FIGS. 1 and 2, the workpiece W to which the tape T is attached is placed on the holding surface 20a of the holding means 2 so that the upper surface Wa thereof faces up. To do.
Then, the suction force generated by the suction source 23 is transmitted to the holding surface 20a of the holding means 2 through the suction path 22, and the workpiece W is sucked and held on the holding surface 20a of the holding means 2.

Next, as shown in FIG. 2, the holding means 2 holding the workpiece W is moved in the Y-axis direction by using a moving means (not shown), and the rotating grinding wheel 340 passes through the center of the workpiece W. Align as follows. After that, the rotating means 24 is used to rotate the workpiece W held on the holding means 2 and the holding surface 20a of the holding means 2 around the rotating shaft 25.

Next, the spindle motor 32 is used to drive the spindle 30, and the spindle 30 is rotated about the rotation shaft 35. As a result, the mount 33 arranged at the lower end of the spindle 30 and the grinding wheel 34 mounted on the lower surface of the mount 33 rotate.

Then, when an electric signal is sent from the control means 8 to the first grinding feed unit 46, the rotation of the Z-axis motor 42 is controlled by the first grinding feed unit 46 that receives the electric signal. The Z-axis motor 42 rotates the ball screw 40 around the rotation shaft 45 at a rotation speed corresponding to the first grinding feed speed, so that the elevating plate 43 is guided by the guide rail 41 at the first grinding feed speed. It descends in the Z direction, and along with this, the grinding grind 340 supported by the elevating plate 43 via the holder 44 is rotating about the rotation shaft 35, and at the same first grinding feed speed. It descends in the −Z direction and approaches the workpiece W held on the holding means 2. As a result, as shown in FIG. 2, the lower surface 340a of the grinding wheel 340 comes into contact with the upper surface Wa of the workpiece W, and the workpiece W is ground.

During the grinding process, the thickness of the workpiece W is measured using the thickness measuring means 5. Based on the difference in height read by bringing the holding surface height gauge 51 into contact with the holding surface 20a while bringing the wafer upper surface height gauge 50 into contact with the upper surface Wa of the workpiece W, the calculation means 52 performs the work. The thickness of the object W is measured. Grinding is performed at the first grinding feed rate until the thickness of the workpiece W becomes the first thickness, which is thicker than the preset finish thickness. This control is performed by the first grinding feed unit 46.

Then, after grinding the workpiece W to the first thickness, when an electric signal for changing the grinding feed speed is sent from the control means 8 to the second grinding feed unit 47, the electric signal is received. 2 The rotation speed of the Z-axis motor 42 is controlled by the grinding feed portion 47, and the descent speed of the grinding means 3 is switched from the first grinding feed speed to the second grinding feed speed slower than the first grinding feed speed. After switching the descent speed of the grinding means 3 to the second grinding feed rate, the grinding wheel 340 in contact with the upper surface Wa of the workpiece W is further pushed down in the −Z direction, and is subjected to the second grinding feed rate. Grind the work piece W to the finish thickness. This control is performed by the second grinding feed unit 47.
The first grinding feed unit 46 measures the height of the upper surface Wa, which is the surface to be ground, until the upper surface Wa reaches the upper surface height lowered by a preset first grinding amount from the start of grinding. The workpiece may be ground at the first grinding feed rate. Similarly, the second grinding feed unit 47
While measuring the height of the ground upper surface Wa, the first is until the upper surface Wa reaches the finishing height further lowered by the preset second grinding amount from the upper surface height lowered by the first grinding amount. The workpiece may be ground at a second grinding feed rate slower than the grinding feed rate.

During the grinding process of the workpiece W, the rotational speed of the spindle motor 32 is compared with that at the start of grinding due to the load in the rotational direction generated by the contact between the lower surface 340a of the rotating grinding wheel 340 and the upper surface Wa of the workpiece W. There is a risk of slowing down. Therefore, during the grinding process, the rotation speed of the spindle motor 32 is measured by using an encoder or the like (not shown), and feedback control is performed to control the electric power supplied to the spindle motor 32 based on the measurement result. The rotation speed of the motor 32 may be kept at a constant value.

Further, during the grinding process of the workpiece W, the load value applied to the grinding wheel 340 changes according to the change in the state of the grinding wheel 340. For example, when the grinding wheel 340 is clogged or clogged, the load value applied to the grinding wheel 340 becomes large. On the other hand, when the grinding wheel 340 is chipped or abnormally worn, the load value applied to the grinding wheel 340 becomes small.
Therefore, as shown in FIG. 2, during the grinding process, the grinding wheel 340 is applied by measuring the load value using the load value detecting means 6 arranged between the side plate 440 of the holder 44 and the bottom plate 441. Investigate the load value to detect abnormalities that occur during grinding.

During the grinding process, the load applied to the grinding wheel 340 is transmitted to the load value detecting means 6 as follows. As shown in FIG. 2, the side plate 440 of the holder 44 connected to the elevating plate 43 descends in the −Z direction together with the elevating plate 43. On the other hand, when the grinding wheel 340 descends in the −Z direction while abutting on the workpiece W, the grinding wheel 340 is processed as a reaction of the force applied to the workpiece W by the grinding wheel 340 in the −Z direction. A force is received from the object W in the + Z direction, and the housing 31 connected to the grinding wheel 340 is pushed in the + Z direction accordingly, and the bottom plate of the holder 44 connected to the large diameter portion 311 of the housing 31 is connected. The 441 is subjected to a force so as to be pulled up in the + Z direction by the large diameter portion 311.
As described above, when a compressive force is applied from above and below to the load value detecting means 6 sandwiched between the bottom plate 441 and the side plate 440 of the holder 44, the piezoelectric element of the load value detecting means 6 generates a voltage. The voltage is converted into a load value as appropriate. In this way, the load value is measured by the load value detecting means 6.

Similarly, when the load value detecting means 6 is arranged between the lower surface 311b of the large diameter portion 311 of the housing 31 and the upper surface 411a of the bottom plate 411 of the holder 44, the load value detecting means 6 is similarly used. A voltage is generated by the piezoelectric element by applying a compressive force in the vertical direction from the large diameter portion 311 and the bottom plate 411 of the holder 44. The load value can be measured based on this voltage.

FIG. 3A is an example of a graph showing the time change of the load value measured by the load value detecting means 6, and the left part is the time change of the load value in the grinding process at the first grinding speed, and The right part shows the time change of the load value in the grinding process at the second grinding process speed.

FIG. 3B shows a graph of the time change of the load value drawn in FIG. 3A, which shows the load allowed in the grinding process at the first grinding feed rate and the grinding process at the second grinding feed rate. It is a graph in which the upper limit value I1 and I3 of the value are drawn respectively. As shown in FIG. 3B, the load value measured during the grinding process at the first grinding feed rate exceeds the upper limit value I1 at P1, and the recognition unit 81 recognizes this.

3 (c) shows the graphs shown in FIG. 3 (b), and further, the lower limit values I2 and I4 of the load values allowed in the grinding process at the first grinding feed rate and the grinding process at the second grinding feed rate. It is a graph in which each is drawn. As shown in FIG. 3C, the load value measured during the grinding process at the second grinding feed rate is below the lower limit value I4 at P2, and this is recognized by the second recognition unit 83.

As described above, when the load value measured by the load value detecting means 6 exceeds the upper limit value and is recognized by the recognition unit 81 (the measured load value falls below the lower limit value and the second recognition unit 83 (Same as above), for example, an alarm is issued by a notification means (not shown) provided in the grinding device 1, so that the operator is notified that an abnormality has occurred in the grinding process. Alternatively, for example, a display (not shown) for notifying that a grinding process abnormality has occurred is displayed to notify the operator to that effect.
After that, for example, an electric signal is transmitted from the control means 8 to the grinding feed means 4, and the grinding means 3 is driven by the grinding feed means 4 that receives the electric signal, so that the grinding means 3 descends in the −Z direction. Is stopped, and is further raised in the + Z direction, and the grinding wheel 340 that has been in contact with the workpiece W is temporarily retracted upward to interrupt the grinding process.

As described above, by operating the grinding device 1, the upper and lower limit values of the load value in the grinding process at the first grinding feed rate, and the upper limit value and the load value in the grinding process at the second grinding feed rate The lower limit value can be set and the load value can be monitored, which makes it possible to detect abnormalities occurring in the grinding process more accurately.
That is, since the second grinding feed rate is slower than the first grinding feed rate, the upper limit value and the lower limit value set for the second grinding feed rate are larger than the upper limit value and the lower limit value set for the first grinding feed rate. A small value is set.

In the embodiment for carrying out the present invention, the upper limit value and the lower limit value of the load value corresponding to the two grinding feed rates consisting of the first grinding feed rate and the second grinding feed rate are set as described above. Therefore, the configuration is not limited to the configuration in which an abnormality occurring in the grinding process is detected by using the set upper limit value and lower limit value.
For example, when grinding one workpiece W, such as a third grinding feed speed, a fourth grinding feed speed, etc., grinding is performed by combining more types of grinding feed speeds. In the same way, the upper and lower limits of the load value corresponding to each grinding feed speed should be set based on past machining experience, and the load value applied to the grinding wheel 340 during grinding should be monitored. This makes it possible to detect abnormalities that occur in the grinding process at each grinding feed speed.

1: Grinding device 10: Base 11: Column 12: Cover 13: Bellows 2: Holding means 20: Suction part 20a: Holding surface 21: Frame body 22: Suction path 23: Suction source 24: Rotating means 25: Rotating shaft 3: Grinding means 30: Spindle 31: Housing 310: Small diameter part 311: Large diameter part 311b: Bottom surface of large diameter part 32: Spindle motor 33: Mount 34: Grinding wheel 340: Grinding grind 340a: Bottom surface of grinding grind 341: Base 35 : Rotating shaft 4: Grinding feed means 40: Ball screw 41: Guide rail 42: Z-axis motor 43: Elevating plate 44: Holder 440: Holder side plate 441: Holder bottom plate 441a: Bottom plate top surface 441d: Hole 45: Rotating shaft 46 : 1st grinding feed section 47: 2nd grinding feed section 5: Thickness measuring means 50: Wafer top surface height gauge 51: Holding surface height gauge 52: Calculation means 6: Load value detecting means 6b: Bottom surface of load value detecting means 8: Control means 80: Upper limit value setting unit 81: Recognition unit 82: Lower limit value setting unit 83: Second recognition unit W: Work piece Wa: Top surface of work piece Wb: Bottom surface of work piece T: Tape I1: First grinding feed Upper limit value of load value during grinding at speed I2: Lower limit value of load value during grinding at first grinding feed speed I3: Upper limit value of load value during grinding at second grinding feed speed I4: Lower limit of load value during grinding at 2nd grinding feed rate P1: Point that exceeds the upper limit of load value during grinding at 1st grinding feed rate P2: Load during grinding at 2nd grinding feed rate A point below the lower limit of the value

Claims (3)

A holding means for holding the work piece,
A grinding means that rotates a spindle equipped with a grinding wheel in which a grinding wheel is arranged in an annular shape and grinds a workpiece held by the holding means with the grinding wheel.
A grinding feed means for moving the holding means and the grinding means in directions relatively close to each other and away from each other.
A thickness measuring means for measuring the thickness of the work piece,
A load value detecting means for detecting a load value when the grinding wheel moves in a direction of approaching the workpiece held by the holding means and the grinding wheel pushes the workpiece.
A grinding device including a control means,
The grinding feed means is
The first grinding feed section that grinds the workpiece to a first thickness that is thicker than the finish thickness preset at the first grinding feed rate, and the second grinding feed rate that is slower than the first grinding feed rate to the finish thickness. Equipped with a second grinding feed for grinding the workpiece,
The control means
Based on the measurement results measured in the past grinding process, the load value detecting means detects each grinding feed rate when grinding at the first grinding feed rate and when grinding at the second grinding feed rate. Upper limit value setting unit that sets the upper limit value of the load value to be
A recognition unit that recognizes that the load value detected by the load value detecting means exceeds the respective upper limit values during grinding at the first grinding feed rate and the second grinding feed rate. Grinding device equipped. A holding means for holding the work piece,
A grinding means that rotates a spindle equipped with a grinding wheel in which a grinding wheel is arranged in an annular shape and grinds a workpiece held by the holding means with the grinding wheel.
A grinding feed means for moving the holding means and the grinding means in directions relatively close to each other and away from each other.
An upper surface height measuring means for measuring the upper surface height of the workpiece held by the holding means,
A load value detecting means for detecting a load value when the grinding wheel moves in a direction of approaching the workpiece held by the holding means and the grinding wheel pushes the workpiece.
A grinding device including a control means,
The grinding feed means is
While measuring the height of the upper surface, the first grinding feed portion that grinds the workpiece at the first grinding feed speed until the upper surface reaches the height of the upper surface lowered by the preset first grinding amount, and the upper surface. While measuring the height, the second grinding feed speed is slower than the first grinding feed speed until the upper surface reaches the finished height lowered by the preset second grinding amount from the upper surface height lowered by the first grinding amount. Equipped with a second grinding feed section that grinds the workpiece at the grinding feed speed,
The control means
Based on the measurement results measured in the past grinding process, the load value detecting means detects each grinding feed rate when grinding at the first grinding feed rate and when grinding at the second grinding feed rate. Upper limit value setting unit that sets the upper limit value of the load value to be
A recognition unit that recognizes that the load value detected by the load value detecting means exceeds the respective upper limit values during grinding at the first grinding feed rate and the second grinding feed rate. Grinding device equipped. The control means has a load value for each of the feed rates when grinding at the first grinding feed rate and when grinding at the second grinding feed rate, based on the measurement results set in the past grinding process. A lower limit value setting unit that sets the lower limit value of the load value detected by the detection means,
A second recognition unit that recognizes that the load value detected by the load value detecting means exceeds the respective lower limit values during grinding at the first grinding feed rate and the second grinding feed rate. ,
The grinding apparatus according to claim 1 or 2.

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