JP2024068494A - Clamp device, control method, and control program of the same - Google Patents

Abstract

To improve determination accuracy of the opening and closing state of a pair of arm parts.SOLUTION: A wire clamp device 70 includes: a pair of arm parts 72a, 72b; a drive part 76 which has a piezo element 80; a supply part 90a being the supply part that is configured to supply the drive voltage to the piezo element 80, and that increases or decreases the voltage of a DC component in such a state that the frequency of an AC component is set to the resonant frequency fr of the pair of arm parts 72a, 72b; a detection part 90b that detects an output signal output from the driven piezo element 80; and a determination part 90c that determines the opening and closing state of the pair of arm parts 72a and 72b on the basis of the generation state of a harmonic component of the resonant frequency in the output signal.SELECTED DRAWING: Figure 1

Description

The present invention relates to a clamping device and a control method and control program for the same.

The clamping device, for example, includes a pair of arms that clamp the workpiece, a drive unit having a piezoelectric element that opens and closes the pair of arms, and a supply unit that supplies voltage to the piezoelectric element. For example, when testing or calibrating the clamping operation of the pair of arms, the clamping device may be required to have a function for determining the open/closed state of the pair of arms.

For example, Patent Document 1 discloses a calibration method including the steps of applying a predetermined frequency that vibrates the pair of arms in the opening and closing directions to drive the piezoelectric element, detecting whether or not the tips of the pair of arms have collided based on the output current output from the piezoelectric element when the pair of arms are vibrating in the opening and closing directions, calculating a reference voltage for the pair of arms in the closed state based on the detection result, and calibrating the drive voltage applied to the piezoelectric element based on the reference voltage.

International Publication No. 2018/038135

However, in the calibration method described in Patent Document 1, the determination of the open/closed state of the pair of arms may be affected by machine differences such as the ease of vibration, the ease of transmission of vibration, and the ease of detecting the output current.

The present invention was made in consideration of these circumstances, and aims to improve the accuracy of determining the open/closed state of the pair of arms.

The clamping device according to one aspect of the present invention includes a pair of arms that clamp the workpiece, a drive unit having a piezoelectric element that opens and closes the pair of arms, a supply unit that generates a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed and is configured to be able to supply the drive voltage to the piezoelectric element, and that increases or decreases the voltage of the DC component while setting the frequency of the AC component to the resonant frequency of the pair of arms, a detection unit that detects an output signal output from the driven piezoelectric element, and a determination unit that determines the open/closed state of the pair of arms based on the occurrence status of harmonic components of the resonant frequency in the output signal.

According to the above aspect, the open/closed state of the pair of arms is determined based on the occurrence of harmonic components in the output signal, so that the influence of machine differences such as the ease of vibration, the ease of vibration transmission, and the ease of detecting the output signal can be reduced when determining the open/closed state.

As one aspect of the above, the clamp device may further include a registration unit that registers the voltage of the DC component when the pair of arms switch between the open state and the closed state as a reference voltage, and a calibration unit that calibrates the operating voltage applied to the piezoelectric element based on the reference voltage.

According to the above aspect, highly accurate calibration can be performed based on the highly accurate determination of the open/close state, thereby improving the accuracy and stabilizing the opening and closing operation of the clamp device.

As one aspect of the above, the detection unit may detect the output current output from the piezoelectric element as the output signal.

According to the above aspect, the output current from the pair of arms can be expressed using the time derivative of the output voltage, so even if a change in magnitude is difficult to detect as an output voltage, it may be a detectable change in the output current. Therefore, the detection accuracy of the detection unit can be improved, and the calibration accuracy can be improved.

As one aspect of the above, the determination unit may calculate the intensity of the harmonic components of the resonant frequency in the output signal by performing a Fourier transform on the output current.

According to the above aspect, the components contained in the output signal can be separated based on frequency and the intensity of each component can be compared.

As one aspect of the above, the determination unit may calculate the intensity ratio of the harmonic components to the fundamental component of the resonant frequency in the output signal.

According to the above aspect, the open/close state can be determined based on an intensity ratio that is easier to compare than harmonic components that are easily affected by noise, improving the accuracy of the determination.

As one aspect of the above, the determination unit may calculate the rate of change of the intensity ratio relative to the voltage change of the DC component.

According to the above aspect, the open/close state can be determined based on the rate of change of the intensity ratio, which is easier to compare than the intensity ratio, which is more susceptible to the effects of noise, thereby improving the accuracy of the determination.

As one aspect of the above, the registration unit may register the first voltage as the reference voltage when the rate of change in the intensity ratio when the voltage of the DC component is changed from the first voltage to the second voltage exceeds a threshold value.

According to the above aspect, when the pair of arms switch between the open state and the closed state, the rate of change of the intensity ratio changes significantly, so the first voltage when the rate of change of the intensity ratio exceeds a threshold value can be used as the reference voltage.

As one aspect of the above, when the pair of arm parts contact each other in the closed state, the registration unit may register the voltage of the DC component when the pair of arm parts switch from the closed state to the open state as the reference voltage when the pair of arm parts start to open, and may register the voltage of the DC component when the pair of arm parts switch from the open state to the closed state as the reference voltage when the pair of arm parts finish closing.

According to the above aspect, by registering both the reference voltage when the opening starts and the reference voltage when the closing finishes, it is possible to calibrate both the voltage used when the pair of arms are opened and when they are closed, thereby further improving the accuracy and stabilization of the opening and closing operations.

As one aspect of the above, when the pair of arms clamp a calibration jig with higher dimensional accuracy than the workpiece in the closed state, the registration unit may register the voltage of the DC component when the pair of arms switch from the closed state to the open state as the reference voltage when the pair of arms start to open, and may register the voltage of the DC component when the pair of arms switch from the open state to the closed state as the reference voltage when the pair of arms finish closing.

According to the above aspect, by registering both the reference voltage at the beginning of opening and the reference voltage at the end of closing when clamping the calibration jig, it is possible to calibrate both the voltage used when opening and closing the pair of arms, thereby further improving the accuracy and stabilizing the opening and closing operations. By clamping a calibration jig with higher dimensional accuracy than the workpiece when determining the reference voltage, it is possible to improve the accuracy of the calibration compared to when clamping the workpiece.

As one aspect of the above, when the pair of arms clamp the workpiece in the closed state, the registration unit may register the voltage of the DC component when the pair of arms switch from the closed state to the open state as the reference voltage when the pair of arms start to open, and may register the voltage of the DC component when the pair of arms switch from the open state to the closed state as the reference voltage when the pair of arms finish closing.

According to the above aspect, by registering both the reference voltage at the beginning of opening and the reference voltage at the end of closing when clamping the workpiece, it is possible to calibrate both the voltage used when opening and closing the pair of arms, thereby further improving the accuracy and stabilizing the opening and closing operations. By clamping the workpiece when determining the reference voltage, it is possible to simplify the configuration of the clamping device and the calibration work compared to clamping a calibration jig.

In one aspect of the above, the registration unit may register, as a first reference voltage, the voltage of the DC component when the pair of arms switch between the open and closed states when the pair of arms contact each other in the closed state, and register, as a second reference voltage, the voltage of the DC component when the pair of arms switch between the open and closed states when the pair of arms clamp a calibration jig or workpiece with higher dimensional accuracy than the workpiece in the closed state, and calculate and register the rate of change of the amount of opening and closing of the pair of arms relative to the voltage applied to the piezoelectric element based on the voltage difference between the first and second reference voltages and the dimensions of the calibration jig or workpiece in the opening and closing direction of the pair of arms, and the calibration unit may calibrate the operating voltage applied to the piezoelectric element based on the rate of change of the amount of opening and closing.

According to the above aspect, by calibrating the amount of opening and closing of the pair of arms relative to the operating voltage, it is possible to further improve the accuracy and stability of the opening and closing operation.

As one aspect of the above, the harmonic components of the resonant frequency may include multiple harmonic components.

According to the above aspect, the accuracy of determining the open/closed state of the pair of arms based on the harmonic components is improved, which improves the accuracy of the calibration and further improves the accuracy and stabilization of the opening and closing operation.

As one aspect of the above, the supply unit may increase or decrease the frequency of the AC component while setting the voltage of the DC component to a voltage at which the pair of arms are in an open state, the determination unit may determine the resonant state of the pair of arms based on the occurrence of a component in the output signal that is caused by the collision of the pair of arms, and the registration unit may register the frequency of the AC component when the resonant state of the pair of arms is strongest as the resonant frequency of the pair of arms.

According to the above aspect, even if the resonant frequency fluctuates due to machine differences or changes over time, the resonant frequency of the pair of arms can be found before calibration is performed, improving the accuracy of the calibration and further improving the accuracy and stabilization of the opening and closing operations.

A control method according to another aspect of the present invention is a control method for a clamping device including a pair of arms for clamping a workpiece, a drive unit having a piezoelectric element for opening and closing the pair of arms, and a supply unit configured to generate a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed and supply the drive voltage to the piezoelectric element, the control method including: increasing or decreasing the voltage of the DC component with the frequency of the AC component set to the resonant frequency of the pair of arms; detecting an output signal output from the driven piezoelectric element; and determining the open/closed state of the pair of arms based on the occurrence status of harmonic components of the resonant frequency in the output signal.

With the above configuration, the open/closed state of the pair of arms is determined based on the occurrence of harmonic components in the output signal, so the influence of machine differences such as the ease of vibration, the ease of vibration transmission, and the ease of detecting the output signal can be reduced when determining the open/closed state.

A control program according to another aspect of the present invention is a control program for operating a clamping device that includes a pair of arms for clamping a workpiece, a drive unit having a piezoelectric element for opening and closing the pair of arms, and a supply unit configured to generate a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed and supply the drive voltage to the piezoelectric element, and causes a computer to increase or decrease the voltage of the DC component while setting the frequency of the AC component to the resonant frequency of the pair of arms, detect an output signal output from the driven piezoelectric element, and determine the open/closed state of the pair of arms based on the occurrence status of harmonic components of the resonant frequency in the output signal.

With the above configuration, the open/closed state of the pair of arms is determined based on the occurrence of harmonic components in the output signal, so the influence of machine differences such as the ease of vibration, the ease of vibration transmission, and the ease of detecting the output signal can be reduced when determining the open/closed state.

The present invention can improve the accuracy of determining the open/closed state of a pair of arms.

1 is a diagram showing an overall outline of a wire bonding apparatus according to an embodiment of the present invention; FIG. 2 is a top view of a bonding arm of the wire bonding apparatus of FIG. 1 . 2 is a bottom view of a bonding arm of the wire bonding apparatus of FIG. 1 . FIG. 2 is a perspective view of the wire clamp device of FIG. 1 . 13 is a flow chart illustrating a method for registering a resonant frequency. 13 is a graph showing a Fourier transform of an output current when the tip of an arm part collides. 5 is a flowchart showing a part of a calibration method for a wire clamp device according to an embodiment of the present invention. 5 is a flowchart showing a part of a calibration method for a wire clamp device according to an embodiment of the present invention. 13 is a graph obtained by Fourier transforming an output current immediately before the arm portion starts to open and reaches an open state. 13 is a graph obtained by Fourier transforming an output current immediately after the arm portion starts to open and is in an open state. 5 is a flowchart showing a part of a calibration method for a wire clamp device according to an embodiment of the present invention. 5 is a flowchart showing a part of a calibration method for a wire clamp device according to an embodiment of the present invention.

The following describes an embodiment of the present invention. In the following description of the drawings, identical or similar components are denoted by the same or similar reference numerals. The drawings are illustrative, and the dimensions and shapes of each part are schematic, and the technical scope of the present invention should not be interpreted as being limited to the embodiment.

<Wire bonding device>
First, the configuration of a wire bonding apparatus 1 according to an embodiment of the present invention will be described with reference to Figures 1 to 4. Figure 1 is a diagram showing an overall schematic of the wire bonding apparatus according to this embodiment. Figure 2 is a top view of a bonding arm in the wire bonding apparatus of Figure 1. Figure 3 is a bottom view of the bonding arm in the wire bonding apparatus of Figure 1. Figure 4 is a perspective view of the wire clamp device of Figure 1.

As shown in FIG. 1, the wire bonding apparatus 1 includes an XY drive mechanism 10, a Z drive mechanism 12, a bonding arm 20, an ultrasonic horn 30, a bonding tool 40, a load sensor 50, an ultrasonic transducer 60, a wire clamp device 70, and a wire bonding control unit 90.

The XY drive mechanism 10 is configured to be slidable in the XY axis directions (directions parallel to the bonding surface), and the XY drive mechanism (linear motor) 10 is provided with a Z drive mechanism (linear motor) 12 that can swing the bonding arm 20 in the Z axis direction (direction perpendicular to the bonding surface).

The bonding arm 20 is supported by the support shaft 14 and is configured to be freely swingable relative to the XY drive mechanism 10. The bonding arm 20 is formed in a substantially rectangular parallelepiped shape so as to extend from the XY drive mechanism 10 to the bonding stage 16 on which the workpiece (e.g., semiconductor die or substrate) 18 to be bonded is placed. The support shaft 14 is, for example, at substantially the same height as the working surface (bonding surface) of the workpiece 18. The bonding arm 20 includes an arm base end 22 attached to the XY drive mechanism 10, an arm tip end 24 located at the tip side of the arm base end 22 and to which an ultrasonic horn 30 is attached, and a flexible connecting portion 23 that connects the arm base end 22 and the arm tip end 24. The connecting portion 23 is composed of slits 25a, 25b of a predetermined width extending from the top surface 21a of the bonding arm 20 toward the bottom surface 21b, and a slit 25c of a predetermined width extending from the bottom surface 21b of the bonding arm 20 toward the top surface 21a. In this way, the connecting portion 23 is configured as a locally thin portion by each of the slits 25a, 25b, 25c, so that the arm tip portion 24 is configured to bend relative to the arm base end portion 22.

As shown in Figs. 1 and 3, a recess 26 is formed on the bottom surface 21b side of the bonding arm 20 to accommodate the ultrasonic horn 30. The ultrasonic horn 30 is attached to the arm tip 24 by a horn fixing screw 32 while being accommodated in the recess 26 of the bonding arm 20. The ultrasonic horn 30 holds the bonding tool 40 at its tip protruding from the recess 26, and an ultrasonic vibrator 60 that generates ultrasonic vibrations is provided in the recess 26. The ultrasonic vibrator 60 generates ultrasonic vibrations, which are transmitted to the bonding tool 40 by the ultrasonic horn 30, and ultrasonic vibrations can be applied to the bonding target via the bonding tool 40. The ultrasonic vibrator 60 is, for example, a piezoelectric vibrator.

1 and 2, slits 25a and 25b are formed in order on the top surface 21a side of the bonding arm 20 from the top surface 21a to the bottom surface 21b. The upper slit 25a is formed wider than the lower slit 25b. A load sensor 50 is provided in the upper slit 25a which is formed wider. The load sensor 50 is fixed to the arm tip 24 by a preload screw 52. The load sensor 50 is arranged so as to be sandwiched between the arm base end 22 and the arm tip 24. That is, the load sensor 50 is offset from the central axis of the longitudinal direction of the ultrasonic horn 30 in the direction of approaching and retracting from the bonding target, and is attached between the center of rotation of the bonding arm 20 and the mounting surface of the ultrasonic horn 30 at the arm tip 24 (i.e., the tip surface of the arm tip 24 on the bonding tool 40 side). As described above, the ultrasonic horn 30 that holds the bonding tool 40 is attached to the arm tip 24. When a load is applied to the tip of the bonding tool 40 due to a reaction force from the bonding target, the arm tip 24 bends relative to the arm base end 22, making it possible for the load sensor 50 to detect the load. The load sensor 50 is, for example, a piezoelectric load sensor.

The bonding tool 40 is for inserting the wire 42, and is, for example, a capillary with an insertion hole 41. In this case, the wire 42 used for bonding is inserted into the insertion hole 41 of the bonding tool 40, and a part of the wire 42 can be paid out from the tip. In addition, a pressing part for pressing the wire 42 is provided at the tip of the bonding tool 40. The pressing part has a shape that is rotationally symmetrical around the axial direction of the insertion hole 41 of the bonding tool 40, and has a pressing surface on the underside around the insertion hole 41.

The bonding tool 40 is attached to the ultrasonic horn 30 in a replaceable manner by spring force or the like. A wire clamp device 70 is provided above the bonding tool 40 and is configured to clamp or release the wire 42 at a predetermined timing. A wire tensioner 46 is provided further above the wire clamp device 70 and is configured to pass the wire 42 through and apply an appropriate tension to the wire 42 during bonding.

The material of the wire 42 is appropriately selected based on ease of processing and low electrical resistance, and may be, for example, gold (Au), copper (Cu) or silver (Ag). The wire 42 is bonded to the first bond point of the workpiece 18 by a free air ball 43 extending from the tip of the bonding tool 40.

Here, with reference to FIG. 4, the wire clamp device 70 according to this embodiment will be described in detail. The wire clamp device 70 corresponds to an example of a clamp device that clamps a workpiece. In the wire clamp device 70, the workpiece is a wire. The wire clamp device 70 includes a pair of arms 72a, 72b and a drive unit 76 attached to the main body of the wire bonding device 1. The pair of arms 72a, 72b have tip ends 73a, 73b for clamping the wire 42 and base ends 74a, 74b, and extend from the tip ends 73a, 73b to the base ends 74a, 74b in a direction approximately perpendicular to the wire axis direction. Clamp pieces 71a, 71b that contact the wire 42 are provided on the opposing surfaces of the tip ends 73a, 73b. In addition, the drive unit 76 is provided with a piezoelectric element 80 that opens and closes the tip ends 73a, 73b of the pair of arms 72a, 72b. The opening and closing operation of the pair of arms 72a, 72b of the piezoelectric element 80 is controlled by supplying a drive voltage from a wire bonding control unit 90 (specifically, a supply unit 90a). The end of the drive unit 76 opposite the pair of arms 72a, 72b is fixed to the body of the wire bonding device 1. Note that FIG. 1 shows the wire clamp device 70 in the state where the extension direction of the pair of arms 72a, 72b is viewed from the tip end 73a, 73b side.

The pair of arms 72a, 72b are connected to the driving unit 76 at their base ends 74a, 74b via a plurality of connecting parts 77a, 77b, 78a, 78b. Specifically, when the pair of arms 72a, 72b are viewed from above in the wire axial direction, the pair of connecting parts 78a, 78b are provided on both outer sides of the pair of arms 72a, 72b, and the pair of connecting parts 77a, 77b are provided at a position sandwiched between the pair of connecting parts 78a, 78b. These connecting parts are configured as elastically deformable constrictions. The pair of connecting parts 77a, 77b are connected to each other by the action part 79. In this configuration, the piezoelectric element 80 is provided between the driving unit 76 and the action part 79 with both ends fixed. When a drive voltage is applied, the piezoelectric element 80 expands and contracts in the direction in which the pair of arms 72a and 72b extend, causing each of the connecting parts 77a, 77b, 78a, and 78b to elastically deform so as to open and close the tip parts 73a and 73b of the pair of arms 72a and 72b. Note that each of the connecting parts 77a, 77b, 78a, and 78b has spring properties in the direction in which the tip parts 73a and 73b close.

The piezoelectric element 80 is, for example, a stacked piezoelectric actuator in which multiple layers of piezoelectric elements are stacked in the direction connecting the driving unit 76 and the acting unit 79.

The pair of arms 72a, 72b (clamp pieces 71a, 71b, tip ends 73a, 73b, and base ends 74a, 74b) are made of, for example, a conductive material.

Next, the operation of the wire clamp device 70 will be described. In a state where no voltage is applied to the piezoelectric element 80, a predetermined load is applied to the tip portions 73a and 73b of the pair of arm portions 72a and 72b in the closing direction. When a drive voltage is applied to the piezoelectric element 80, the piezoelectric element 80 extends in the extension direction of the pair of arm portions 72a and 72b (in other words, the direction connecting the drive portion 76 and the action portion 79) due to the electrostrictive or magnetostrictive effect, which causes the action portion 79 to move in the direction of the pair of arm portions 72a and 72b, thus bending the connecting portions 77a, 77b, 78a, and 78b outward, and the tip portions 73a and 73b are in an open state. The amount of movement of the tip portions 73a and 73b at this time corresponds to the amount of extension of the piezoelectric element 80 expanded according to the ratio of the length from the action portion 79 to the connecting portion and the length from the connecting portion to the tip portions 73a and 73b. Here, when the amount of opening and closing of the pair of arms 72a, 72b is the distance between the clamp pieces 71a, 71b in the opening and closing direction, the amount of movement of the tips 73a, 73b corresponds to the amount of change in the amount of opening and closing of the pair of arms 72a, 72b.

In more detail, when the drive voltage applied to the piezoelectric element 80 is increased from zero, the wire clamp load by the tips 73a, 73b decreases in proportion to the voltage value applied to the piezoelectric element 80, and when the voltage value reaches the reference voltage value, the clamp pieces 71a, 71b of the tips 73a, 73b are in contact with each other with the wire clamp load being zero. When the voltage value is further increased, the tips 73a, 73b open in a direction away from each other. The state in which the tips 73a, 73b are in contact with each other is the "closed state" of the pair of arms 72a, 72b, and the state in which the tips 73a, 73b are away from each other is the "open state" of the pair of arms 72a, 72b.

Returning to FIG. 1, the wire bonding apparatus 1 according to this embodiment will be further described. The wire bonding control unit 90 is connected to each of the components, such as the XY drive mechanism 10, the Z drive mechanism 12, the ultrasonic horn 30 (ultrasonic transducer 60), the load sensor 50, and the wire clamp device 70, so that signals can be sent and received between them. The wire bonding control unit 90 controls the operation of these components, so that the necessary processing for wire bonding can be performed.

The wire bonding control unit 90 is also connected to an operation unit 92 for inputting control information and a display unit 94 for outputting control information. This allows an operator to input the necessary control information through the operation unit 92 while viewing the screen on the display unit 94. The wire bonding control unit 90 is a computer device equipped with a CPU (Central Processing Unit) and memory, and the memory stores a bonding program for performing the processing required for wire bonding and various data processed by each component of the wire bonding control unit 90, which will be described later. The wire bonding control unit 90 is configured to control the operations required to calibrate the wire clamp device, which will be described later. For example, the wire bonding control unit 90 executes each operation for calibration by having the CPU execute a program stored in the memory.

The wire bonding control unit 90 according to this embodiment includes a supply unit 90a, a detection unit 90b, a determination unit 90c, a registration unit 90d, and a calibration unit 90e.

The supply unit 90a generates a DC or pulsating voltage and supplies it to the piezoelectric element 80. Specifically, the supply unit 90a supplies a DC voltage as a working voltage to the piezoelectric element 80 in the wire bonding process, and supplies a pulsating current in which a DC component and an AC component are superimposed as a driving voltage to the piezoelectric element 80 in the calibration process of the wire clamp device 70. By supplying a pulsating current to the piezoelectric element 80, the DC component applies a load to the tips 73a and 73b of the pair of arm parts 72a and 72b in the opposite direction (opening direction) to the wire clamp load, and the AC component of the pulsating current vibrates the tips 73a and 73b of the pair of arm parts 72a and 72b in the opening and closing direction. Here, the voltage of the DC component of the pulsating current is variable within a range in which the pair of arm parts 72a and 72b can be switched between an open state and a closed state. In addition, the frequency of the AC component of the pulsating current is variable within a range that includes the resonant frequency fr that is determined based on the natural angular frequency of the pair of arms 72a, 72b. For example, the supply unit 90a increases or decreases the voltage of the DC component stepwise or continuously during one stage of the calibration process. In addition, the supply unit 90a increases or decreases the frequency of the AC component stepwise or continuously during one stage of the calibration process.

The detection unit 90b detects the output current from the piezoelectric element 80 when the pair of arms 72a, 72b vibrate in the opening and closing direction by driving the piezoelectric element 80 by the supply unit 90a. The output current is an example of an output signal output from the driven piezoelectric element 80. When the pair of arms 72a, 72b vibrate in the opening and closing direction, a potential difference is generated in the piezoelectric element 80. This potential difference changes depending on whether the pair of arms 72a, 72b collide with each other. This potential difference also changes depending on whether the pair of arms 72a, 72b are in a resonant state. The detection unit 90b detects a change in the output current based on such a change in the potential difference of the piezoelectric element 80. The detection unit 90b stores data related to the detected output current in the memory of the wire bonding control unit 90.

The determination unit 90c acquires data on the output current stored in the memory, and determines the open/closed state of the pair of arm portions 72a, 72b based on the occurrence of harmonic components of the resonant frequency fr in the output current. When an AC voltage of the resonant frequency fr is applied to the piezoelectric element 80 while the pair of arm portions 72a, 72b are in the open state, harmonic components are detected as the output current in addition to the fundamental wave component of the resonant frequency fr. The harmonic components of the resonant frequency fr contained in the output current become very small or nearly zero when the pair of arm portions 72a, 72b are in the closed state. Using this, the determination unit 90c determines the open/closed state of the pair of arm portions 72a, 72b.

Specifically, the supply unit 90a changes the voltage of the DC component while setting the frequency of the AC component of the drive voltage to the resonant frequency fr, and the determination unit 90c determines the open/closed state of the pair of arms 72a, 72b based on the presence or absence and strength of harmonic components in the output current.

At this time, the determination unit 90c performs a Fourier transform on the output current and calculates the intensity of the fundamental component of the resonant frequency fr and the intensity of the harmonic component of the resonant frequency fr. Here, the harmonic component of the resonant frequency fr may include multiple higher harmonics including the second harmonic f2 of the resonant frequency fr, and includes, for example, the second harmonic f2, the third harmonic f3, and the fourth harmonic f4. Furthermore, the determination unit 90c calculates the intensity ratio of the harmonic component to the fundamental component of the resonant frequency fr, and calculates the rate of change of the intensity ratio with respect to the voltage change of the DC component in the drive voltage. Then, when the rate of change of the intensity ratio exceeds a threshold value, the determination unit 90c determines that the pair of arm portions 72a, 72b have switched between the open state and the closed state.

Since the intensity of the harmonic components is smaller than that of the fundamental wave components, the judgment unit 90c improves the judgment accuracy by making a judgment based on the rate of change of the intensity ratio relative to the voltage change. However, if the judgment unit 90c can determine the open/closed state of the pair of arm portions 72a, 72b, it may also make a judgment based on the intensity ratio of the harmonic components to the fundamental wave component, or based on the intensity of the harmonic components.

In order to identify the resonance frequency fr used in the step of determining the open/closed state of the pair of arm parts 72a, 72b, the determination unit may determine the resonance state of the pair of arm parts 72a, 72b. For example, the determination unit 90c determines the resonance state of the pair of arm parts 72a, 72b based on the occurrence state of a component caused by the collision of the pair of arm parts 72a, 72b in the output current detected by the detection unit 90b. When the pair of arm parts 72a, 72b in the open state vibrates and collides with each other, the output current includes a component caused by the collision of the pair of arm parts 72a, 72b with each other (hereinafter referred to as a "collision component") in addition to a component caused by the AC component of the drive voltage of the pair of arm parts 72a, 72b. Using this, the determination unit 90c determines the resonance state of the pair of arm parts 72a, 72b.

Specifically, the supply unit 90a changes the frequency of the AC component of the drive voltage while setting the voltages of the DC and AC components of the drive voltage so that the pair of arms 72a, 72b collide with each other when vibrating in a resonant state, and do not collide when vibrating in a non-resonant state. The determination unit 90c then determines the open/closed state of the pair of arms 72a, 72b based on the presence or absence and strength of a collision component in the output current.

At this time, the determination unit 90c performs a Fourier transform on the output current to calculate the intensity of the collision component. Here, the frequency fx of the collision component is higher than the fundamental wave of the resonance frequency fr, for example, about five times as high as the resonance frequency fr. The intensity of the collision component is smaller than the intensity of the fundamental wave component of the resonance frequency fr, and is greater than the intensity of the harmonic component of the resonance frequency fr. For example, when the intensity of the collision component exceeds a threshold value, the determination unit 90c determines that the pair of arm portions 72a, 72b are vibrating in a resonant state.

The registration unit 90d registers the voltage of the DC component of the drive voltage when the pair of arms 72a, 72b switch between the open state and the closed state as a reference voltage based on the judgment result of the judgment unit 90c on the open/closed state of the pair of arms 72a, 72b. Here, the reference voltage when the pair of arms 72a, 72b contact each other in the closed state is a DC voltage equivalent to a state in which they contact each other with a substantially zero wire clamp load (zero load point). In addition, the reference voltage when the pair of arms 72a, 72b clamp a wire or a calibration jig with a higher dimensional accuracy than the wire in the closed state is a DC voltage equivalent to a state in which the pair of arms 72a, 72b clamp a wire or a calibration jig with a substantially zero wire clamp load (zero load point). Such a reference voltage may be, for example, the reference voltage when the pair of arm portions 72a, 72b switch from an open state to a closed state, or the reference voltage when the pair of arm portions 72a, 72b switch from a closed state to an open state. In the following, the time when the open state switches to the closed state is referred to as "end of closing" and the time when the closed state switches to the open state is referred to as "start of opening."

The registration unit 90d registers at least one of the reference voltage at the end of closing and the reference voltage at the beginning of opening when the pair of arms 72a, 72b contact each other in the closed state, and the reference voltage at the end of closing and the reference voltage at the beginning of opening when the pair of arms 72a, 72b clamp a wire or a calibration jig. The relationship between the voltage applied to the pair of arms 72a, 72b and the opening amount shows hysteresis. In other words, since the reference voltage at the end of closing and the reference voltage at the beginning of opening are different values, it is preferable that the registration unit 90d registers both the reference voltage at the end of closing and the reference voltage at the beginning of opening. In addition to the above reference voltage, the registration unit 90d calculates and registers the rate of change of the opening amount of the pair of arms 72a, 72b with respect to the voltage applied to the piezoelectric element 80. The data registered by the registration unit 90d is stored in the memory of the wire bonding control unit 90. An example of the calculation of the reference voltage and the rate of change of the opening amount in the registration unit 90d will be described later.

The calibration unit 90e reads data regarding the reference voltage and the rate of change of the opening and closing amount registered by the registration unit 90d from the memory, and calibrates the operating voltage (DC voltage) to be applied to the piezoelectric element 80 in the wire bonding process. In this case, the calibration unit 90e may correct the value of the operating voltage that has already been set, or may set a new operating voltage to be applied to the piezoelectric element 80. In this way, the operating voltage calibrated by the calibration unit 90e is stored in the memory of the wire bonding control unit 90. Then, the supply unit 90a can read the calibrated operating voltage stored in the memory in the wire bonding process, and drive the piezoelectric element 80 based on the operating voltage.

<Calibration method>
Next, a calibration method using the wire clamp device 70 according to the present embodiment will be described with reference to FIGS. 5 to 12. FIG. 5 is a flowchart showing a method for registering a resonance frequency. FIG. 6 is a graph showing a Fourier transform of an output current when the tip of the arm part collides. FIGS. 7 and 8 are flowcharts showing a part of a calibration method for the wire clamp device according to the embodiment of the present invention. FIGS. 7 and 8 are flowcharts showing a part of a calibration method for the wire clamp device according to the embodiment of the present invention. FIGS. 7 and 8 are flowcharts showing a part of a calibration method for the wire clamp device according to the embodiment of the present invention. FIGS. 7 and 8 are flowcharts showing a part of a calibration method for the wire clamp device according to the embodiment of the present invention. FIGS. 7 and 8 are flowcharts showing a part of a calibration method for the wire clamp device according to the embodiment of the present invention. FIGS. 9 and 10 are graphs showing a part of a calibration method for the wire clamp device according to the embodiment of the present invention. FIGS. 11 and 12 are flowchart ... The graphs shown in FIGS. 6, 9, and 10 are obtained by FFT (Fast Fourier Transform) processing of data obtained by sampling the output current at 100 kSPS using a current detection circuit, with the horizontal axis representing frequency and the vertical axis representing intensity.

The calibration method according to this embodiment can be performed using the wire bonding apparatus 1. In addition, the calibration method of the wire clamping apparatus 70 according to this embodiment can be performed when wire bonding is completed (i.e., before the next wire bonding is started), during teaching for wire bonding, etc.

In the calibration method according to one aspect of the present invention, the resonance frequency fr of the pair of arms 72a, 72b is used. Therefore, if the resonance frequency fr varies due to machine differences or changes over time, it is desirable to register the resonance frequency fr immediately before calibration. For this reason, first, a method for registering the resonance frequency fr of the pair of arms 72a, 72b will be described with reference to FIG. 5. Here, as shown in FIG. 6, it is determined whether the pair of arms 72a, 72b are vibrating at the resonance frequency fr based on the occurrence status of collision components at frequency fx. Note that if the resonance frequency fr is known, the process of registering the resonance frequency fr may be omitted.

First, the voltage of the DC component of the drive voltage is set to a voltage that causes the pair of arm portions 72a, 72b to be in an open state, and the frequency of the AC component is set arbitrarily (S11). At this time, the voltage of the AC component of the drive voltage is set to a magnitude that causes the pair of arm portions 72a, 72b to collide with each other when vibrating in a resonant state, but does not collide when vibrating in a non-resonant state. For example, the voltage of the DC component is set to 138V, and the voltage of the AC component is set to 10V.

Next, the frequency of the AC component in the drive voltage is changed (S12). The supply unit 90a changes the frequency of the AC component within a frequency range that includes the expected resonance frequency fr. For example, the supply unit 90a increases the frequency of the AC component from 1.7 kHz to 2.7 kHz in increments of 0.05 kHz. Then, the output current at each frequency is detected (S13).

Next, the resonant state at each frequency is determined based on the output current (S14). The resonant state is determined based on the strength of the frequency fx of the collision component shown in FIG. 6. When the frequency fx of the collision component exceeds a threshold value, it is determined that the pair of arms 72a, 72b are in a resonant state. Then, the frequency of the AC component in the drive voltage when the resonant state is strongest is registered as the resonant frequency fr (S15). In other words, the frequency of the AC component when the frequency fx of the collision component is strongest is registered as the resonant frequency fr. Note that, if there is only one frequency of the AC component determined to be in a resonant state in step S14, the frequency of that AC component is registered as the resonant frequency fr in step S15. The resonant frequency fr is stored in the memory of the wire bonding control unit 90 by the registration unit 90d. The resonant frequency fr is, for example, 2.45 kHz.

Next, referring to FIG. 7, a method for registering a reference voltage at the beginning of opening when the pair of arms 72a, 72b are not clamping anything will be described. Here, as shown in FIG. 9 and FIG. 10, when a drive voltage including an AC component of the resonant frequency fr is applied, it is determined whether the pair of arms 72a, 72b are in an open or closed state based on the generation state of harmonic components near the second harmonic frequency f2 (f2 ≒ fr x 2), the third harmonic frequency f3 (f3 ≒ fr x 3), and the fourth harmonic frequency f4 (f4 ≒ fr x 4) of the resonant frequency fr.

First, the frequency of the AC component of the drive voltage is set to the resonant frequency fr, and the voltage of the DC component is set to a voltage at which the pair of arms 72a, 72b are in a closed state (S21). The resonant frequency fr used here is the one registered in step S15. The supply unit 90a reads the resonant frequency fr from the memory and sets the frequency of the AC component. The supply unit 90a sets the voltage of the DC component to be smaller than the expected reference voltage. For example, the voltage of the DC component is set to 40 V, and the voltage of the AC component is set to 8 V.

Next, the output current is detected, and the intensity ratio of the harmonic components to the fundamental component of the resonant frequency fr is calculated (S22). The output current detected by the current detection circuit in the detection unit 90b is Fourier transformed to calculate peak intensities near 1x (fundamental), 2x (second harmonic f2), 3x (third harmonic f3), and 4x (fourth harmonic f4) of the resonant frequency fr. The intensity of the harmonic components is the sum of the intensities of the second harmonic, third harmonic, and fourth harmonic. The intensity of the harmonic components is divided by the intensity of the fundamental component to calculate the intensity ratio.

The harmonic orders included in the intensity of the harmonic components are not limited to the above. The intensity of any of the second through fourth harmonics may not be included, and the intensity of the fifth or higher harmonics may be included. The intensity of the harmonic components may also be the intensity of a single harmonic order.

Next, the voltage of the DC component in the drive voltage is increased by one step (S23). If the increase in the DC component voltage is too small, the change in the intensity of the harmonic components will be too small, reducing the accuracy of the reference voltage determination, and if the increase in the DC component voltage is too large, the error in the reference voltage will increase. For this reason, it is desirable that the change in the DC component voltage increased by the supply unit 90a in step S23 be about 1V. However, the increase in the DC component voltage is not limited to the above, and may be about 0.5V or about 1.5V.

Next, the output current is detected, and the intensity ratio of the harmonic components to the fundamental component of the resonant frequency fr is calculated (S24). As in step S22, the intensity of the harmonic components is divided by the intensity of the fundamental component to calculate the intensity ratio.

Next, it is determined whether the rate of change in the intensity ratio exceeds a threshold value (S25). The intensity ratio calculated in step S24 is divided by the intensity ratio calculated in step S22 to calculate the rate of change in the intensity ratio. If this rate of change in the intensity ratio exceeds the threshold value, it is determined that the pair of arm portions 72a, 72b have switched from a closed state to an open state. This threshold value is, for example, a value that is set in advance, and is set to an arbitrary value, for example, between 10% and 60%.

The threshold value of the rate of change of the intensity ratio may be a value determined during calibration. For example, the threshold value may be determined based on the average value, maximum value, or median value of the rate of change of the intensity ratio when the voltage of the DC component is increased by any number of steps while the pair of arms 72a, 72b are securely closed. For example, the threshold value may be set to a multiple such as two or three times the average value, maximum value, or median value of the rate of change of the intensity ratio.

If the rate of change in the intensity ratio does not exceed the threshold value (S25 NO), the process returns to step S23, where the voltage of the DC component in the drive voltage is increased by another step, and in step S24, the intensity ratio of the harmonic component to the fundamental component of the resonance frequency fr is calculated. Then, in step S25, the rate of change in the intensity ratio before and after the change in the DC component voltage is calculated, and it is determined whether or not it exceeds the threshold value. In this way, the calculation of the rate of change in the intensity ratio when the DC component voltage is increased in 1V increments is repeated, and if it is determined that the rate of change in the intensity ratio exceeds the threshold value (S25 YES), based on this determination result, the voltage of the DC component before the increase is registered as the reference voltage for the start of opening (S26).

In the example shown in FIG. 9, the voltage of the DC component is 66V, and the intensity ratio of the harmonic components including the second harmonic f2, the third harmonic f3, and the fourth harmonic f4 to the fundamental component is about 3.777%. The rate of change in the intensity ratio when the voltage of the DC component is increased from 65V to 66V is about -3.038%. In the example shown in FIG. 10, the voltage of the DC component is 67V, and the intensity ratio of the harmonic components to the fundamental component is about 6.138%. The rate of change in the intensity ratio when the voltage of the DC component is increased from 66V to 67V is about 62.496%. In this way, when the pair of arm portions 72a, 72b are switched from the closed state to the open state, the rate of change in the intensity ratio becomes much larger than the previous rate of change. Incidentally, the intensity ratio is about 2.935% when the DC component voltage is 40 V, about 3.199% when the DC component voltage is 41 V, and the rate of change in the intensity ratio is about 8.988% when the DC component voltage is increased from 40 V to 41 V. In the range in which the pair of arms 72a, 72b are in the closed state, the intensity ratio is small and is therefore susceptible to the effects of noise, etc., and the rate of change in the intensity ratio can be either positive or negative, but the rate of change in the intensity ratio when the pair of arms 72a, 72b switch from the closed state to the open state is a large positive value.

Next, referring to FIG. 8, a method for registering the reference voltage at the beginning of opening and the rate of change of the opening and closing amount when the pair of arms 72a, 72b clamp the calibration jig will be described. Note that explanations of operations similar to those already described in steps S21 to S26 will be omitted as appropriate.

First, the calibration jig is set between the pair of arms 72a, 72b (S31), and the reference voltage at which the calibration jig begins to open when clamping the calibration jig is registered (S32). In step S32, steps S21 to S26 are executed.

Next, the voltage difference of the reference voltage at the beginning of opening due to the presence or absence of the calibration jig is calculated (S33). The reference voltage at the beginning of opening is different between when the pair of arms 72a, 72b clamp nothing and when the calibration jig is clamped. This is because when the calibration jig is clamped, the pair of arms 72a, 72b in the closed state are separated from each other by the dimension of the calibration jig in the opening and closing direction of the pair of arms 72a, 72b. The reference voltage at the beginning of opening when the calibration jig is clamped is greater than the reference voltage at the beginning of opening when nothing is clamped. Therefore, the voltage difference of the reference voltage at the beginning of opening is calculated by subtracting the reference voltage at the beginning of opening when nothing is clamped registered in step S26 from the reference voltage at the beginning of opening when the calibration jig is clamped registered in step S32.

Next, the rate of change of the opening/closing amount of the pair of arms 72a, 72b with respect to the applied voltage when the pair of arms 72a, 72b start to open is calculated (S34). The voltage difference calculated in step S33 corresponds to the applied voltage added to the piezoelectric element 80 when the opening/closing amount of the pair of arms 72a, 72b is changed by the dimension of the calibration jig in the opening/closing direction. Here, the opening/closing amount of the pair of arms 72a, 72b is the distance between the clamp pieces 71a, 71b in the opening/closing direction. The rate of change of the opening/closing amount of the pair of arms 72a, 72b with respect to the applied voltage is calculated by dividing the dimension of the calibration jig in the opening/closing direction by the voltage difference calculated in step S33.

Next, the rate of change in the amount of opening and closing of the pair of arm portions 72a, 72b at the beginning of opening is registered (S35). The rate of change in the amount of opening and closing calculated in step S34 is stored in the memory of the wire bonding control unit 90.

Next, referring to FIG. 11, we will explain how to register the reference voltage at the end of closing when the pair of arms 72a, 72b do not clamp anything. Note that we will omit explanations of the same contents as those already explained in steps S21 to S26 as appropriate.

First, the frequency of the AC component of the drive voltage is set to the resonant frequency fr, and the voltage of the DC component is set to a voltage at which the pair of arms 72a, 72b are in an open state (S41). Step S41 differs from step S21 in that the voltage of the DC component of the drive voltage is set to a voltage at which the pair of arms 72a, 72b are in an open state rather than a closed state. For example, the voltage of the DC component is set to 100 V, and the voltage of the AC component is set to 5 V.

Next, the output current is detected, and the intensity ratio of the harmonic component to the fundamental component of the resonant frequency fr is calculated (S42). Step S42 is the same as step S22.

Next, the voltage of the DC component of the drive voltage is lowered by one step (S43). Step S43 differs from step S23 in that the voltage of the DC component is lowered instead of increased. The amount of change in the voltage of the DC component in step S43 is the same as in step S23, for example, about 1 V.

Next, the output current is detected, and the intensity ratio of the harmonic component to the fundamental component of the resonant frequency fr is calculated (S44). Step S44 is the same as step S24.

Next, it is determined whether the rate of change of the intensity ratio exceeds a threshold value (S45), and based on the result of this determination, the voltage of the DC component before it is lowered is registered as the reference voltage at the end of closing (S46). Step S45 differs from step S25 in that a different threshold value is set, and the threshold value in step S45 is set to zero, for example.

Specifically, the intensity of the harmonic components decreases as the pair of arms 72a and 72b move from an open state to a closed state, so the rate of change in the intensity ratio due to the voltage drop is a negative value. However, immediately after switching to the closed state, the balance between the input and the reaction changes due to the change in the open/closed state of the pair of arms 72a and 72b, so the rate of change in the intensity ratio is a positive value. After the pair of arms 72a and 72b are in the closed state, the rate of change in the intensity ratio randomly repeats positive and negative values. As an example, when the voltage of the DC component is 57V, the intensity ratio is about 6.383%, and when the voltage of the DC component is dropped from 58V to 57V, the rate of change in the intensity ratio is about -13.314%. When the voltage of the DC component is 56V, the intensity ratio is about 5.303%, and when the voltage of the DC component is dropped from 57V to 56V, the rate of change in the intensity ratio is about -16.933%. When the DC component voltage is 52V, the intensity ratio is about 3.540%, and when the DC component voltage is lowered from 53V to 52V, the rate of change in the intensity ratio is about -22.834%. When the DC component voltage is 51V, the intensity ratio is about 3.591%, and when the DC component voltage is lowered from 52V to 51V, the rate of change in the intensity ratio is about 1.420%. In the above case, when the DC component voltage is 52V, the pair of arms 72a, 72b have finished closing, and the intensity ratio will not decrease any further, so even when the DC component voltage is lowered from 52V to 51V, the intensity ratio did not decrease. Therefore, 52V, which is the voltage before the drop when the rate of change in the intensity ratio becomes a positive value, is registered as the reference voltage at the end of closing.

The threshold value of the rate of change of the intensity ratio at the end of closing is not limited to zero. For example, as long as the rate of change of the intensity ratio changes within the above range, the threshold value may be set to any value between -10% and 1%. In addition, in the step of determining the open/closed state of the pair of arms 72a, 72b at the end of closing, the open/closed state may be determined based on whether the absolute value of the rate of change of the intensity ratio is below the threshold value. Specifically, when the absolute value of the rate of change of the intensity ratio is greater than the threshold value, it may be determined that the pair of arms 72a, 72b are in the open state, and when the absolute value of the rate of change of the intensity ratio is smaller than the threshold value, it may be determined that the pair of arms 72a, 72b are in the closed state. This is because when the pair of arms 72a, 72b approach the closed state in the open state, the rate of change of the intensity ratio is large, but when the pair of arms 72a, 72b are in the closed state, the intensity ratio does not change substantially, that is, the rate of change of the intensity ratio becomes small.

Next, referring to FIG. 12, a method for registering the reference voltage at the end of closing and the rate of change of the opening and closing amount when the pair of arms 72a, 72b clamp the calibration jig will be described. Note that explanations of operations similar to those already described in steps S31 to S35 will be omitted as appropriate.

First, the calibration jig is set between the pair of arms 72a, 72b (S51), and the reference voltage at the end of closing when clamping the calibration jig is registered (S52). In step S52, steps S41 to S46 are executed.

Next, the voltage difference of the reference voltage at the end of closing due to the presence or absence of the calibration jig is calculated (S53). The voltage difference of the reference voltage at the end of closing is calculated by subtracting the reference voltage at the end of closing when nothing is clamped, which was registered in step S46, from the reference voltage at the end of closing when the calibration jig is clamped, which was registered in step S52.

Next, the rate of change in the amount of opening and closing of the pair of arms 72a, 72b relative to the applied voltage at the end of closing of the pair of arms 72a, 72b is calculated (S54). Step S54 is the same as step S34.

Next, the rate of change in the amount of opening and closing of the pair of arms 72a, 72b at the end of closing is registered (S55). Step S55 is the same as step S35.

Finally, the operating voltage is calibrated (S36). The operating voltage is calibrated based on the registered reference voltage at the start of opening of the pair of arm portions 72a, 72b, the rate of change of the opening amount at the start of opening, and the reference voltage at the end of closing, and the rate of change of the opening amount at the end of closing. By performing a wire bonding process using the wire clamp device 70 with the calibrated operating voltage, it is possible to accurately grasp the opening and closing operation of the pair of arm portions 72a, 72b of the wire clamp device 70 that corresponds to the operating voltage. This allows for highly accurate and stable wire bonding.

This calibration method is preferably performed each time the wire bonding process is performed in a different manner, for example, when wire bonding is performed with different wire diameters or in different temperature environments. This is particularly effective because it allows calibration according to the ease of opening the wire clamp device 70 that corresponds to each situation.

In addition, in steps S31 to S35 and steps S51 to S55, the wire 42 to be wire-bonded after calibration may be used instead of the calibration jig.

The following describes some or all of the embodiments of the present invention. Note that the present invention is not limited to the following descriptions.

[Appendix 1]
a drive unit 76 having a piezoelectric element 80 for opening and closing the pair of arm portions 72a, 72b; a supply unit 90a configured to generate a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed and to supply the drive voltage to the piezoelectric element 80, the supply unit 90a raising or lowering the voltage of the DC component while setting the frequency of the AC component to the resonant frequency of the pair of arm portions 72a, 72b; a detection unit 90b that detects an output signal output from the driven piezoelectric element 80; and a determination unit 90c that determines the open/closed state of the pair of arm portions 72a, 72b based on the generation status of harmonic components of the resonant frequency in the output signal.

According to [Appendix 1], the open/closed state of the pair of arms 72a, 72b is determined based on the occurrence of harmonic components in the output signal, so that the influence of machine differences such as the ease of vibration, the ease of vibration transmission, and the ease of detecting the output signal can be reduced in determining the open/closed state.

[Appendix 2]
The clamp device described in [Appendix 1] further includes a registration unit 90d that registers the DC component voltage when the pair of arm portions 72a, 72b switch between an open state and a closed state as a reference voltage, and a calibration unit 90e that calibrates the operating voltage applied to the piezoelectric element 80 based on the reference voltage.

According to the aspect of [Appendix 2], highly accurate calibration can be performed based on the highly accurate determination of the open/close state, thereby improving the accuracy and stabilizing the opening and closing operation of the clamp device 70.

[Appendix 3]
The detector 90b detects the output current output from the piezoelectric element 80 as the output signal.

According to the aspect of [Appendix 3], the output current from the pair of arms 72a, 72b can be expressed using the time derivative of the output voltage, so even if a change in magnitude is difficult to detect as the output voltage, it may be a change in magnitude that can be detected as the output current. Therefore, the detection accuracy of the detection unit 90b can be improved, and the calibration accuracy can be improved.

[Appendix 4]
The clamp device 70 according to [Supplementary Note 3], wherein the determination unit 90c calculates the intensity of the harmonic components of the resonance frequency in the output signal by performing a Fourier transform on the output current.

According to the aspect of [Appendix 4], the components contained in the output signal can be separated based on frequency and the intensity of each component can be compared.

[Appendix 5]
The clamp device 70 according to [Appendix 4], wherein the determination unit 90c calculates an intensity ratio of a harmonic component to a fundamental component of a resonant frequency in the output signal.

According to the aspect of [Appendix 5], the open/close state can be determined based on an intensity ratio that is easier to compare than harmonic components that are easily affected by noise, thereby improving the accuracy of the determination.

[Appendix 6]
The clamp device 70 according to [Supplementary Note 5], wherein the determination unit 90c calculates a rate of change in the intensity ratio with respect to a voltage change of the DC component.

According to the aspect of [Appendix 6], the open/close state can be determined based on the rate of change of the intensity ratio, which is easier to compare than the intensity ratio, which is more susceptible to the effects of noise, thereby improving the accuracy of the determination.

[Appendix 7]
The clamp device 70 described in [Appendix 6], wherein the registration unit 90d registers the first voltage as a reference voltage when the rate of change in the intensity ratio when the voltage of the DC component is changed from a first voltage to a second voltage exceeds a threshold value.

According to the aspect of [Appendix 7], when the pair of arms 72a, 72b switch between the open state and the closed state, the rate of change of the intensity ratio changes significantly, so the first voltage when the rate of change of the intensity ratio exceeds a threshold value can be used as the reference voltage.

[Appendix 8]
The registration unit 90d, when the pair of arm portions 72a, 72b are in contact with each other in the closed state, registers the DC component of the voltage when the pair of arm portions 72a, 72b switch from a closed state to an open state as a reference voltage when the pair of arm portions 72a, 72b start to open, and registers the DC component of the voltage when the pair of arm portions 72a, 72b switch from an open state to a closed state as a reference voltage when the pair of arm portions 72a, 72b finish closing. This is the clamp device 70 described in any one of [Appendix 2] to [Appendix 7].

According to the aspect of [Appendix 8], by registering both the reference voltage at the beginning of opening and the reference voltage at the end of closing, it is possible to calibrate both the voltage used when opening and closing the pair of arm portions 72a, 72b, thereby further improving the accuracy and stabilization of the opening and closing operations.

[Appendix 9]
The registration unit 90d, when the pair of arm portions 72a, 72b clamp a calibration jig having higher dimensional accuracy than the wire 42 in a closed state, registers the DC component voltage when the pair of arm portions 72a, 72b switch from a closed state to an open state as a reference voltage when the pair of arm portions 72a, 72b start to open, and registers the DC component voltage when the pair of arm portions 72a, 72b switch from an open state to a closed state as a reference voltage when the pair of arm portions 72a, 72b finish closing. This clamp device 70 is described in any one of [Appendix 2] to [Appendix 7].

According to the aspect of [Appendix 9], by registering both the reference voltage at the beginning of opening and the reference voltage at the end of closing when clamping the calibration jig, it is possible to calibrate both the voltage used when opening and closing the pair of arm portions 72a, 72b, thereby further improving the accuracy and stabilizing the opening and closing operations. By clamping a calibration jig with higher dimensional accuracy than the wire 42 when determining the reference voltage, it is possible to improve the accuracy of the calibration compared to clamping the wire 42.

[Appendix 10]
The registration unit 90d, when the pair of arm portions 72a, 72b clamp the wire 42 in the closed state, registers the DC component voltage when the pair of arm portions 72a, 72b switch from a closed state to an open state as a reference voltage when the pair of arm portions 72a, 72b start to open, and registers the DC component voltage when the pair of arm portions 72a, 72b switch from an open state to a closed state as a reference voltage when the pair of arm portions 72a, 72b finish closing. This is a clamp device 70 described in any one of [Appendix 2] to [Appendix 7].

According to the aspect of [Appendix 10], by registering both the reference voltage at the beginning of opening and the reference voltage at the end of closing when clamping the wire 42, it is possible to calibrate both the voltage used when opening and closing the pair of arms 72a, 72b, thereby further improving the accuracy and stabilizing the opening and closing operations. By clamping the workpiece when determining the reference voltage, it is possible to simplify the configuration of the clamp device and the calibration work compared to clamping a calibration jig.

[Appendix 11]
The registration unit 90d registers, when the pair of arms 72a, 72b are in contact with each other in the closed state, a voltage of a DC component when the pair of arms 72a, 72b switch between an open state and a closed state as a first reference voltage, and registers, when the pair of arms 72a, 72b are in contact with each other in the closed state, a voltage of a DC component when the pair of arms 72a, 72b switch between an open state and a closed state as a second reference voltage when the pair of arms 72a, 72b clamp a calibration jig or the wire 42 having higher dimensional accuracy than the wire 42 in the closed state. and registering a rate of change of the amount of opening and closing of the pair of arm portions 72 a, 72 b with respect to the voltage applied to the piezoelectric element 80 based on a voltage difference between the first reference voltage and the second reference voltage and the dimension of the calibration jig or wire 42 in the opening and closing direction of the pair of arm portions 72 a, 72 b, and a calibration unit 90 e calibrates the operating voltage applied to the piezoelectric element 80 based on the rate of change of the amount of opening and closing.

According to the aspect of [Appendix 11], the opening and closing amount of the pair of arms 72a, 72b can also be calibrated with respect to the operating voltage, thereby further improving the accuracy and stabilization of the opening and closing operation.

[Appendix 12]
The clamp device 70 according to any one of [Supplementary Note 1] to [Supplementary Note 11], wherein the harmonic components of the resonant frequency include multiple harmonic components.

According to the aspect of [Appendix 12], the accuracy of determining the open/closed state of the pair of arm portions 72a, 72b based on harmonic components is improved, so the accuracy of calibration is improved, and the accuracy and stabilization of the opening and closing operation can be further improved.

[Appendix 13]
The supply unit 90a increases or decreases the frequency of the AC component while setting the voltage of the DC component to a voltage at which the pair of arm portions 72a, 72b are in an open state, the determination unit 90c determines the resonant state of the pair of arm portions 72a, 72b based on the occurrence state of components in the output signal due to collision between the pair of arm portions 72a, 72b, and the registration unit 90d registers the frequency of the AC component when the resonant state of the pair of arm portions 72a, 72b is strongest as the resonant frequency of the pair of arm portions 72a, 72b.

According to the aspect of [Appendix 13], even if the resonant frequency fluctuates due to machine differences or changes over time, the resonant frequency of the pair of arm portions 72a, 72b can be found before calibration is performed, improving the accuracy of the calibration and further improving the accuracy and stabilization of the opening and closing operations.

[Appendix 14]
A control method for a wire clamping device 70 including a pair of arm portions 72a, 72b that clamp a wire 42, a drive unit 76 having a piezoelectric element 80 that opens and closes the pair of arm portions 72a, 72b, and a supply unit 90a configured to generate a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed and to be able to supply the drive voltage to the piezoelectric element 80, the control method including: increasing or decreasing the voltage of the DC component while setting the frequency of the AC component to a resonant frequency of the pair of arm portions 72a, 72b; detecting an output signal output from the driven piezoelectric element 80; and determining the open/closed state of the pair of arm portions 72a, 72b based on the generation status of harmonic components of the resonant frequency in the output signal.

According to the aspect of [Appendix 14], the open/closed state of the pair of arms 72a, 72b is determined based on the occurrence of harmonic components in the output signal, so that the influence of machine differences such as the ease of vibration, the ease of vibration transmission, and the ease of detecting the output signal can be reduced in determining the open/closed state.

[Appendix 15]
A control program for operating a wire clamping device 70 including a pair of arm portions 72a, 72b for clamping a wire 42, a drive unit 76 having a piezoelectric element 80 for opening and closing the pair of arm portions 72a, 72b, and a supply unit 90a configured to generate a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed and supply the drive voltage to the piezoelectric element 80. The control program causes a computer to execute the following operations: increase or decrease the voltage of the DC component while setting the frequency of the AC component to the resonance frequency of the pair of arm portions 72a, 72b; detect an output signal output from the driven piezoelectric element 80; and determine the open/closed state of the pair of arm portions 72a, 72b based on the generation status of harmonic components of the resonance frequency in the output signal.

According to the aspect of [Appendix 15], the open/closed state of the pair of arms 72a, 72b is determined based on the occurrence of harmonic components in the output signal, so that the influence of machine differences such as the ease of vibration, the ease of vibration transmission, and the ease of detecting the output signal can be reduced in determining the open/closed state.

As described above, one aspect of the present invention can improve the accuracy of determining the open/closed state of a pair of arms.

The above-described embodiments are intended to facilitate understanding of the present invention, and are not intended to limit the interpretation of the present invention. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those exemplified, and may be modified as appropriate. Furthermore, configurations shown in different embodiments may be partially substituted or combined.

REFERENCE SIGNS LIST 1 wire bonding apparatus 70 wire clamp apparatus 72a, 72b arm section 73a, 73b tip section 74a, 74b base section 76 drive section 90 wire bonding control section 90a supply section 90b detection section 90c determination section 90d registration section 90e calibration section

Claims (15)

A pair of arms for clamping the workpiece;
A drive unit having a piezoelectric element that opens and closes the pair of arms;
a supply unit configured to generate a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed and to be capable of supplying the drive voltage to the piezoelectric element, the supply unit increasing or decreasing the voltage of the DC component in a state in which the frequency of the AC component is set to a resonance frequency of the pair of arms;
A detection unit that detects an output signal output from the driven piezoelectric element;
a determination unit that determines an open/closed state of the pair of arms based on a generation state of harmonic components of the resonant frequency in the output signal. a registration unit that registers, as a reference voltage, a voltage of the DC component when the pair of arm portions are switched between an open state and a closed state;
and a calibration unit that calibrates a voltage to be applied to the piezoelectric element based on the reference voltage.
The clamping device of claim 1 . The detection unit detects an output current output from the piezoelectric element as the output signal.
The clamping device of claim 2. The determination unit calculates an intensity of a harmonic component of the resonance frequency in the output signal by performing a Fourier transform on the output current.
The clamping device of claim 3. The determination unit calculates an intensity ratio of a harmonic component to a fundamental wave component of the resonance frequency in the output signal.
The clamping device of claim 4. The determination unit calculates a rate of change of the intensity ratio with respect to a voltage change of the DC component.
The clamping device of claim 5. the registration unit registers the first voltage as a reference voltage when a rate of change in the intensity ratio when the voltage of the DC component is changed from a first voltage to a second voltage exceeds a threshold value.
The clamping device of claim 6. The registration unit is
When the pair of arms contact each other in a closed state,
registering the voltage of the DC component when the pair of arm portions switch from a closed state to an open state as a reference voltage when the pair of arm portions start to open;
The voltage of the DC component when the pair of arm portions are switched from an open state to a closed state is registered as a reference voltage at the end of closing of the pair of arm portions.
The clamping device of claim 2. The registration unit is
In a case where the pair of arms clamp a calibration jig having a higher dimensional accuracy than the workpiece in a closed state,
registering the voltage of the DC component when the pair of arm portions switch from a closed state to an open state as a reference voltage when the pair of arm portions start to open;
The voltage of the DC component when the pair of arm portions are switched from an open state to a closed state is registered as a reference voltage at the end of closing of the pair of arm portions.
The clamping device of claim 2. The registration unit is
When the pair of arms clamp the workpiece in a closed state,
registering the voltage of the DC component when the pair of arm portions switch from a closed state to an open state as a reference voltage when the pair of arm portions start to open;
The voltage of the DC component when the pair of arm portions are switched from an open state to a closed state is registered as a reference voltage at the end of closing of the pair of arm portions.
The clamping device of claim 2. The registration unit is
When the pair of arm portions are in contact with each other in a closed state, a voltage of the DC component at the time when the pair of arm portions switch between an open state and a closed state is registered as a first reference voltage;
When the pair of arms clamp a calibration jig or the workpiece having a higher dimensional accuracy than the workpiece in a closed state, a voltage of the DC component when the pair of arms switch between an open state and a closed state is registered as a second reference voltage;
calculating and registering a rate of change in an amount of opening and closing of the pair of arms relative to a voltage applied to the piezoelectric element based on a voltage difference between the first reference voltage and the second reference voltage and a dimension of the calibration jig or the workpiece in an opening and closing direction of the pair of arms;
The calibration unit calibrates a voltage to be applied to the piezoelectric element based on a rate of change of the opening and closing amount.
The clamping device of claim 2. The harmonic components of the resonant frequency include a plurality of harmonic components.
The clamping device of claim 1 . the supply unit increases or decreases a frequency of the AC component in a state in which a voltage of the DC component is set to a voltage at which the pair of arm portions are in an open state,
the determination unit determines a resonant state of the pair of arms based on a generation state of a component in the output signal that is caused by a collision of the pair of arms,
The registration unit registers a frequency of the AC component when a resonance state of the pair of arms is strongest as a resonance frequency of the pair of arms.
The clamping device of claim 2. A pair of arms for clamping the workpiece;
A drive unit having a piezoelectric element that opens and closes the pair of arms;
A method for controlling a clamping device comprising: a supply unit configured to generate a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed, and to supply the drive voltage to the piezoelectric element,
increasing or decreasing a voltage of the DC component in a state where a frequency of the AC component is set to a resonance frequency of the pair of arms;
Detecting an output signal output from the driven piezoelectric element;
determining an open/closed state of the pair of arms based on a generation state of harmonic components of the resonant frequency in the output signal. A pair of arms for clamping the workpiece;
A drive unit having a piezoelectric element that opens and closes the pair of arms;
A control program for operating a clamping device comprising: a supply unit configured to generate a drive voltage in which a frequency-variable AC component and a voltage-variable DC component are superimposed, and to supply the drive voltage to the piezoelectric element,
On the computer,
increasing or decreasing a voltage of the DC component in a state where a frequency of the AC component is set to a resonance frequency of the pair of arms;
Detecting an output signal output from the driven piezoelectric element;
and determining an open/closed state of the pair of arms based on a generation state of a harmonic component of the resonance frequency in the output signal.

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