Clamp device, and control method and control program for clamp device

Abstract

The wire clamping device (70) comprises a pair of arm parts (72a, 72b); a drive unit (76) having a piezoelectric element (80); a supply unit (90a) which is configured so as to be able to supply a drive voltage to the piezoelectric element (80), and which increases or decreases the voltage of the DC component in a state in which the frequency of the AC component is set to the resonance frequency (fr) of the pair of arm units (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 / close state of the pair of arm sections (72a, 72b) on the basis of the generation state of a harmonic component of the resonance frequency in the output signal.

Description

Technical Field

[0001] The present invention relates to a clamping device and a control method and a control program thereof. Background Art

[0002] The clamping device includes, for example, a pair of arms for clamping a workpiece, a driving unit having a piezoelectric element for opening and closing the pair of arms, and a supply unit for supplying voltage to the piezoelectric element. For example, when testing or calibrating the clamping action of the pair of arms, the clamping device may be required to have a function of determining the open and closed state of the pair of arms.

[0003] For example, Patent Document 1 discloses a calibration method, which includes the following steps: a step of applying a prescribed frequency to vibrate a pair of arms in an opening and closing direction to drive a piezoelectric element; a step of detecting whether a collision occurs at the front end portions of a pair of arms based on an output current output from the piezoelectric element when the pair of arms vibrate in the opening and closing direction; a step of calculating a reference voltage for a closed state of the pair of arms based on the detection result; and a step of calibrating a driving voltage applied to the piezoelectric element based on the reference voltage.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2018 / 038135 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, in the calibration method described in Patent Document 1, determination of the open / closed state of the pair of arms may be affected by mechanical differences such as susceptibility to vibration, susceptibility to vibration transmission, and susceptibility to output current detection.

[0009] The present invention has been made in view of such circumstances, and an object of the present invention is to improve the accuracy of determining the open / closed state of a pair of arms.

[0010] Technical means of solving problems

[0011] A clamping device of one form of the present invention includes: a pair of arms for clamping a workpiece; a driving portion having a piezoelectric element for opening / closing the pair of arms; a supply portion configured to generate a driving voltage superimposed with a frequency-variable AC component and a voltage-variable DC component and capable of supplying the driving voltage to the piezoelectric element, and increasing or decreasing 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 portion for detecting an output signal output from the driven piezoelectric element; and a determination portion for determining the open / closed state of the pair of arms based on the generation of a harmonic component of the resonant frequency in the output signal.

[0012] According to the described form, since the opening and closing states of a pair of arms are determined based on the generation of harmonic components in the output signal, the influence of mechanical errors such as the ease of vibration, the ease of vibration transmission, and the ease of output signal detection can be reduced in the determination of the opening and closing states.

[0013] As one form, the clamping device may also include: a registration unit that registers a DC component voltage when a pair of arms are switched between an open state and a closed state as a reference voltage; and a calibration unit that calibrates a use voltage applied to the piezoelectric element based on the reference voltage.

[0014] According to the above aspect, it is possible to perform highly accurate calibration based on the highly accurate determination result of the open / closed state, and thus it is possible to improve the accuracy and stabilize the opening / closing operation of the clamp device.

[0015] As the above-described aspect, the detection unit may detect an output current output from the piezoelectric element as an output signal.

[0016] According to the above aspect, the output current from the pair of arms can be represented by the time differential of the output voltage, so even a change in magnitude that is difficult to detect as the output voltage can sometimes become a change in magnitude that can be detected as the output current. Therefore, the detection accuracy of the detection unit can be improved, and the accuracy of calibration can be improved.

[0017] As the above-described aspect, the determination unit may calculate the intensity of the harmonic component of the resonance frequency in the output signal by performing Fourier transform on the output current.

[0018] According to the above aspect, the components included in the output signal can be separated based on the frequency, and the intensity of each component can be compared.

[0019] As the above-described aspect, the determination unit may calculate an intensity ratio of a harmonic component of the resonance frequency in the output signal to a fundamental wave component.

[0020] According to the above aspect, the open / closed state can be determined based on the intensity ratio of the harmonic components that are more susceptible to the influence of noise and are more easily compared, thereby improving the determination accuracy.

[0021] As the above-described aspect, the determination unit may calculate a rate of change of the intensity ratio with respect to a voltage change of the DC component.

[0022] According to the above aspect, the open / closed state can be determined based on the change rate of the intensity ratio which is more easily affected by noise than the intensity ratio which is easier to compare, and the determination accuracy can be improved.

[0023] As the above aspect, the registration unit may register the first voltage as the reference voltage when a change rate of an intensity ratio when changing the voltage of the DC component from the first voltage to the second voltage exceeds a threshold value.

[0024] According to the above aspect, when the pair of arms switch between the open state and the closed state, the change rate of the intensity ratio changes significantly. Therefore, the first voltage when the change rate of the intensity ratio exceeds the threshold value can be set as the reference voltage.

[0025] As one form, it may also be that when a pair of arms are in contact with each other in a closed state, the registration unit registers a DC component voltage when the pair of arms are switched from a closed state to an open state as a reference voltage for the pair of arms to start opening, and registers a DC component voltage when the pair of arms are switched from an open state to a closed state as a reference voltage for the pair of arms to finish closing.

[0026] According to the above aspect, by registering both the reference voltage for starting opening and the reference voltage for ending closing, the voltage used when a pair of arms are opened and the voltage used when they are closed can be calibrated, thereby achieving further improvement in the accuracy and stabilization of the opening and closing action.

[0027] As one form, it may be that when a pair of arms are in a closed state clamping a calibration fixture with a higher dimensional accuracy than the processed object, the registration unit registers the DC component voltage when the pair of arms are switched from a closed state to an open state as a reference voltage for the pair of arms to start opening, and registers the DC component voltage when the pair of arms are switched from an open state to a closed state as a reference voltage for the pair of arms to finish closing.

[0028] According to the above aspect, by registering the reference voltage for the start of opening and the reference voltage for the end of closing when clamping the calibration fixture, the voltage used when the pair of arms are opened and the voltage used when they are closed can be calibrated, thereby further improving and stabilizing the accuracy of the opening and closing action. By clamping the calibration fixture with a higher dimensional accuracy than the object to be processed when obtaining the reference voltage, the accuracy of the calibration can be improved compared to the case where the object to be processed is clamped.

[0029] As one form, it may also be that when a pair of arms clamp a processed object in a closed state, the registration unit registers a DC component voltage when the pair of arms are switched from a closed state to an open state as a reference voltage for the pair of arms to start opening, and registers a DC component voltage when the pair of arms are switched from an open state to a closed state as a reference voltage for the pair of arms to finish closing.

[0030] According to the above embodiment, by registering the reference voltage for the start of opening and the reference voltage for the end of closing when clamping the processed object, the voltage used when the pair of arms are opened and the voltage used when they are closed can be calibrated, thereby further improving the accuracy and stabilizing the opening and closing action. By clamping the processed object when obtaining the reference voltage, the structure and calibration operation of the clamping device can be simplified compared to the case of clamping the calibration fixture.

[0031] As one form, it may also be: when the pair of arms are in contact with each other in a closed state, the registration unit registers the DC component voltage when the pair of arms are switched between the open state and the closed state as a first reference voltage; when the pair of arms are in a closed state, clamping a correction fixture or a processed object with higher dimensional accuracy than the processed object, the DC component voltage when the pair of arms are switched between the open state and the closed state is registered as a second reference voltage; based on the voltage difference between the first reference voltage and the second reference voltage, and the size of the correction fixture or the processed object in the opening and closing direction of the pair of arms, the rate of change of the opening and closing amount of the pair of arms relative to the voltage applied to the piezoelectric element is calculated and registered; and the calibration unit calibrates the use voltage applied to the piezoelectric element based on the rate of change of the opening and closing amount.

[0032] According to the above aspect, by also calibrating the opening and closing amounts of the pair of arms with respect to the operating voltage, it is possible to further improve the accuracy and stabilize the opening and closing operation.

[0033] As the above-mentioned one aspect, the harmonic component of the resonance frequency may include a plurality of harmonic components.

[0034] 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, so the accuracy of calibration is improved, and further improvement and stabilization of the opening / closing operation can be achieved.

[0035] As one form, it may be that: the supply unit increases or decreases the frequency of the AC component while setting the voltage of the DC component to a voltage at which a pair of arms are in an open state, the determination unit determines the resonant state of the pair of arms based on the generation condition of the component caused by the collision of the pair of arms in the output signal, and the registration unit registers the frequency of the AC component when the resonant state of the pair of arms becomes strongest as the resonant frequency of the pair of arms.

[0036] According to the above aspect, even when the resonance frequency varies due to mechanical error or time-dependent changes, the resonance frequency of a pair of arms can be obtained before calibration is performed, thereby improving the accuracy of calibration and achieving further improvement and stabilization of the opening and closing operation.

[0037] Another form of the control method of the present invention is a control method for a clamping device, wherein the clamping device includes: a pair of arms for clamping a processed object; a driving portion having a piezoelectric element for opening / closing the pair of arms; and a supply portion configured to generate a driving voltage superimposed with a frequency-variable AC component and a voltage-variable DC component and capable of supplying the driving voltage to the piezoelectric element, wherein the control method for the clamping device includes: increasing or decreasing the voltage of the DC component while setting the frequency of the AC component 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 generation of a harmonic component of the resonant frequency in the output signal.

[0038] According to the structure, since the opening and closing state of a pair of arms is determined based on the generation status of the harmonic components in the output signal, the influence of mechanical errors such as the ease of vibration, the ease of vibration transmission, and the ease of detection of the output signal can be reduced in the determination of the opening and closing state.

[0039] Another form of the control program of the present invention is a control program for operating a clamping device, wherein the clamping device includes: a pair of arms for clamping a processed object; a driving portion having a piezoelectric element for opening / closing the pair of arms; and a supply portion configured to generate a driving voltage superimposed with a frequency-variable AC component and a voltage-variable DC component and capable of supplying the driving voltage to the piezoelectric element, wherein the control program causes a computer to execute: increasing or decreasing the voltage of the DC component while setting the frequency of the AC component 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 generation of a harmonic component of the resonant frequency in the output signal.

[0040] According to the structure, since the opening and closing state of a pair of arms is determined based on the generation status of the harmonic components in the output signal, the influence of mechanical errors such as the ease of vibration, the ease of transmission of vibration, and the ease of detection of the output signal can be reduced in the determination of the opening and closing state.

[0041] Effects of the Invention

[0042] According to the present invention, it is possible to improve the accuracy of determining the open and closed states of a pair of arms. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] [ Figure 1 ] is a diagram showing an overall overview of a wire bonding device according to an embodiment of the present invention.

[0044] [ Figure 2 ]yes Figure 1 Top view of a bonding arm in a wire bonding apparatus.

[0045] [ Figure 3 ]yes Figure 1 A bottom view of a bonding arm in a wire bonding apparatus.

[0046] [ Figure 4 ]yes Figure 1 A three-dimensional view of a wire clamping device.

[0047] [ Figure 5 ] is a flowchart showing a method for registering a resonance frequency.

[0048] [ Figure 6 ] is a graph obtained by Fourier transforming the output current when the front end of the arm collides.

[0049] [ Figure 7 ] is a flowchart showing a portion of a calibration method for a wire clamping device according to an embodiment of the present invention.

[0050] [ Figure 8 ] is a flowchart showing a portion of a calibration method for a wire clamping device according to an embodiment of the present invention.

[0051] [ Fig. 9 ] is a graph obtained by Fourier transforming the output current immediately before the arm portion enters the open state when it starts to open.

[0052] [ Fig.10 ] is a graph obtained by Fourier transforming the output current immediately after the arm portion enters the open state when the arm portion starts to open.

[0053] [ Fig.11 ] is a flowchart showing a portion of a calibration method for a wire clamping device according to an embodiment of the present invention.

[0054] [ Fig.12 ] is a flowchart showing a portion of a calibration method for a wire clamping device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following is an explanation of the embodiments of the present invention. In the following drawings, the same or similar components are represented by the same or similar symbols. The drawings are examples, and the size or shape of each part is schematic, and the technical scope of the invention of this application should not be limited to the embodiments.

[0056] <Wire bonding device>

[0057] First, refer to Figures 1 to 4 The structure of a wire bonding apparatus 1 according to one embodiment of the present invention will be described. Figure 1 It is a diagram schematically showing the entire wire bonding apparatus according to the present embodiment. Figure 2 yes Figure 1 Top view of a bonding arm in a wire bonding apparatus. Figure 3 yes Figure 1 A bottom view of a bonding arm in a wire bonding apparatus. Figure 4 yes Figure 1 A three-dimensional view of a wire clamping device.

[0058] like Figure 1 As shown, 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 vibrator 60 , a wire clamping device 70 and a wire bonding control unit 90 .

[0059] The XY drive mechanism 10 is configured to be able to slide in the XY axis direction (direction parallel to the bonding surface), and 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).

[0060] The bonding arm 20 is supported by the support shaft 14 and is configured to be swingable relative to the XY drive mechanism 10. The bonding arm 20 is formed into a substantially rectangular parallelepiped in a manner extending from the XY drive mechanism 10 to the bonding table 16 on which the workpiece (e.g., semiconductor grain or substrate) 18 to be bonded is placed. The support shaft 14 is, for example, at a height substantially the same as the working surface (bonding surface) of the workpiece 18. The bonding arm 20 includes: an arm base end 22 mounted on the XY drive mechanism 10, an arm front end 24 located at the front end side of the arm base end 22 and mounted with an ultrasonic horn 30, and a flexible connecting portion 23 connecting the arm base end 22 and the arm front end 24. The connecting portion 23 includes a slit 25a of a predetermined width extending from the top surface 21a of the bonding arm 20 in the direction of the bottom surface 21b, a slit 25b, and a slit 25c of a predetermined width extending from the bottom surface 21b of the bonding arm 20 in the direction of the top surface 21a. In this way, since the connection portion 23 is partially formed as a thin-walled portion by the slits 25 a , 25 b , and 25 c , the arm distal end portion 24 is configured to bend relative to the arm proximal end portion 22 .

[0061] like Figure 1 and Figure 3 As shown, a recess 26 for accommodating an ultrasonic horn 30 is formed on the bottom surface 21b side of the bonding arm 20. The ultrasonic horn 30 is mounted on the arm front end 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 the front end protruding from the recess 26, and an ultrasonic vibrator 60 for generating ultrasonic vibration is provided in the recess 26. The ultrasonic vibration generated by the ultrasonic vibrator 60 is transmitted to the bonding tool 40 through the ultrasonic horn 30, and the ultrasonic vibration can be imparted to the bonding object via the bonding tool 40. The ultrasonic vibrator 60 is, for example, a piezoelectric vibrator.

[0062] In addition, if Figure 1 and Figure 2As shown, on the top surface 21a side of the joining arm 20, a slit 25a and a slit 25b are formed in sequence from the top surface 21a to the bottom surface 21b. The upper slit 25a is formed to be wider than the lower slit 25b. Moreover, a load sensor 50 is provided in the upper slit 25a formed to be wider. The load sensor 50 is fixed to the front end portion 24 of the arm by a pre-stressing screw 52. The load sensor 50 is configured to be sandwiched between the base end portion 22 of the arm and the front end portion 24 of the arm. That is, the load sensor 50 is offset from the central axis in the longitudinal direction of the ultrasonic horn 30 in the direction of contact / separation relative to the joining object, and is installed between the rotation center of the joining arm 20 and the mounting surface of the ultrasonic horn 30 of the front end portion 24 of the arm (that is, the front end surface of the front end portion 24 of the arm on the side of the joining tool 40). Furthermore, as described above, the ultrasonic horn 30 that holds the bonding tool 40 is mounted on the arm front end portion 24. Therefore, when a load is applied to the front end of the bonding tool 40 due to the reaction force from the bonding object, the arm front end portion 24 bends relative to the arm base end portion 22, and the load can be detected by the load sensor 50. The load sensor 50 is, for example, a piezoelectric element load sensor.

[0063] The bonding tool 40 is used to insert the wire 42, and is, for example, a capillary provided 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 fed out from the front end thereof. In addition, a pressing portion for pressing the wire 42 is provided at the front end of the bonding tool 40. The pressing portion 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 lower surface around the insertion hole 41.

[0064] The bonding tool 40 is replaceably mounted on the ultrasonic horn 30 by a spring force or the like. In addition, a wire clamping device 70 is provided above the bonding tool 40, and the wire clamping device 70 is configured to constrain or release the wire 42 at a predetermined timing. A wire tensioner 46 is provided above the wire clamping device 70, and the wire tensioner 46 is configured to insert the wire 42 and apply appropriate tension to the wire 42 being bonded.

[0065] The material of the wire 42 can be appropriately selected in terms of ease of processing and low resistance, and for example, gold (Au), copper (Cu) or silver (Ag) can be used. In addition, the free air ball 43 of the wire 42 extending from the front end of the bonding tool 40 is bonded to the first bonding point of the workpiece 18.

[0066] Here, refer to Figure 4The details of the wire clamping device 70 of this embodiment will be described. The wire clamping device 70 is an example of a clamping device for clamping a workpiece. In the wire clamping device 70, the workpiece is a wire. The wire clamping device 70 includes: a pair of arm portions 72a, 72b, and a driving unit 76 mounted on the main body of the wire bonding device 1. The pair of arm portions 72a, 72b have a front end portion 73a, a front end portion 73b for clamping the wire 42, and a base end portion 74a, a base end portion 74b, and extend from the front end portion 73a, the front end portion 73b to the base end portion 74a, the base end portion 74b in a direction substantially orthogonal to the wire axis direction. Clamping pieces 71a, 71b for contacting the wire 42 are provided on mutually facing surfaces of the front end portions 73a, 73b. In addition, a piezoelectric element 80 for opening / closing the front end portions 73a, 73b of the pair of arm portions 72a, 72b is provided. The piezoelectric element 80 controls the opening and closing of the pair of arm portions 72a and 72b by supplying a driving voltage from the wire bonding control unit 90 (specifically, the supply unit 90a). The end of the driving unit 76 opposite to the pair of arm portions 72a and 72b is fixed to the main body of the wire bonding device 1. Figure 1 , a state of the wire clamping device 70 as viewed from the front end portion 73a, the front end portion 73b side along the extending direction of the pair of arm portions 72a, 72b is shown.

[0067] The pair of arm portions 72a and 72b are connected to the driving portion 76 via a plurality of connecting portions 77a, 77b, 78a, and 78b at their base end portions 74a and 74b. Specifically, when the pair of arm portions 72a and 72b are viewed from above in the direction of the wire axis, the pair of connecting portions 78a and 78b are arranged on both outer sides of the pair of arm portions 72a and 72b, and the pair of connecting portions 77a and 77b are arranged at positions clamped by the pair of connecting portions 78a and 78b. These connecting portions are configured as elastically deformable constricted portions. In addition, the pair of connecting portions 77a and 77b are connected to each other by the action portion 79. In this structure, the piezoelectric element 80 is arranged between the driving portion 76 and the action portion 79 in a state where its both ends are fixed. By applying a driving voltage, the piezoelectric element 80 expands and contracts in the extending direction of the pair of arm portions 72a, 72b, thereby, each connecting portion 77a, 77b, 78a, 78b is elastically deformed in a manner that the front end portion 73a, 73b of the pair of arm portions 72a, 72b is opened / closed. In addition, each connecting portion 77a, 77b, 78a, 78b has elasticity in the direction in which the front end portion 73a, 73b is closed.

[0068] The piezoelectric element 80 is, for example, a stacked piezoelectric actuator in which a plurality of piezoelectric elements are stacked in a direction connecting the drive section 76 and the action section 79 .

[0069] The pair of arm portions 72a and 72b (the clamping piece 71a, the clamping piece 71b, the front end portion 73a, the front end portion 73b, and the base end portion 74a, the base end portion 74b) are made of, for example, a conductive material.

[0070] Next, the operation of the wire clamping device 70 will be described. In a state where no voltage is applied to the piezoelectric element 80, the front end portions 73a and 73b of the pair of arm portions 72a and 72b apply a predetermined load in the closing direction. Furthermore, when a driving 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 driving portion 76 and the action portion 79) by electrostrictive or magnetostrictive effect, thereby the action portion 79 moves in the direction of the pair of arm portions 72a and 72b, so that the connecting portions 77a, 77b, 78a, and 78b are bent in the outward direction, and the front end portions 73a and 73b are in an open state. At this time, the movement amount of the front end portion 73a, 73b corresponds to the amount of expansion of the piezoelectric element 80 according to the ratio of the length from the action portion 79 to the connecting portion to the length from the connecting portion to the front end portion 73a, 73b. Here, when the opening and closing amount of the pair of arm portions 72a, 72b is set to the distance between the clamping pieces 71a, 71b in the opening and closing direction, the movement amount of the front end portion 73a, 73b corresponds to the change in the opening and closing amount of the pair of arm portions 72a, 72b.

[0071] When further described, if the driving voltage applied to the piezoelectric element 80 is increased from zero, the wire clamping load generated by the front end portion 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 clamping pieces 71a, 71b of the front end portion 73a, 73b are in contact with each other in a state where the wire clamping load is zero. If the voltage value is further increased, the front end portion 73a, 73b is in an open state in a direction away from each other. The state in which the front end portion 73a, 73b is in contact with each other is defined as the "closed state" of the pair of arm portions 72a, 72b, and the state in which the front end portion 73a, 73b is away from each other is defined as the "open state" of the pair of arm portions 72a, 72b.

[0072] Back to Figure 1 , the wire bonding device 1 of the present embodiment will be further described. The wire bonding control unit 90 is connected to the XY drive mechanism 10, the Z drive mechanism 12, the ultrasonic horn 30 (ultrasonic vibrator 60), the load sensor 50, and the wire clamping device 70 in a manner that enables signal transmission and reception between the structures. The wire bonding control unit 90 controls the actions of these structures, and the processing required for wire bonding can be performed.

[0073] In addition, the wire bonding control unit 90 is connected to an operation unit 92 for inputting control information and a display unit 94 for outputting control information. Thus, the operator can input the required control information through the operation unit 92 while recognizing the screen through the display unit 94. In addition, the wire bonding control unit 90 is a computer device including a central processing unit (CPU) and a memory, etc., in which a bonding program for processing required for wire bonding or various data processed by each component of the wire bonding control unit 90 described later is pre-stored in the memory. The wire bonding control unit 90 is configured to control the required actions when calibrating the wire clamping device described later. For example, the wire bonding control unit 90 performs various actions for calibration by causing the CPU to execute the program stored in the memory.

[0074] The wire bonding control unit 90 of the present embodiment includes a supply unit 90a, a detection unit 90b, a determination unit 90c, a registration unit 90d, and a calibration unit 90e.

[0075] The supply unit 90a generates a direct current or a pulsed current voltage and supplies it to the piezoelectric element 80. Specifically, the supply unit 90a supplies a direct current voltage as a working voltage to the piezoelectric element 80 in the wire bonding process, and supplies a pulsed current with a direct current component and an alternating current component superimposed as a driving voltage to the piezoelectric element 80 in the calibration process of the wire clamping device 70. By supplying a pulsed current to the piezoelectric element 80, a load is applied to the front end portions 73a and 73b of the pair of arm portions 72a and 72b in the opposite direction (opening direction) to the wire clamping load by the direct current component, and the front end portions 73a and 73b of the pair of arm portions 72a and 72b are vibrated in the opening and closing direction by the alternating current component of the pulsed current. Here, the voltage of the direct current component of the pulsed current is variable within a range that can switch the open state and the closed state of the pair of arm portions 72a and 72b. In addition, the frequency of the alternating current component of the pulsed current is variable within a range including a resonance frequency fr determined based on the natural angular vibration frequency of the pair of arm portions 72a and 72b. For example, the supply unit 90a increases or decreases the voltage of the DC component in stages or continuously during the calibration process. In addition, the supply unit 90a increases or decreases the frequency of the AC component in stages or continuously during the calibration process.

[0076] When the pair of arms 72a and 72b are vibrated in the opening and closing direction by driving the piezoelectric element 80 using the supply unit 90a, the detection unit 90b detects the output current from the piezoelectric element 80. The output current is an example of an output signal output from the driven piezoelectric element 80. When the pair of arms 72a and 72b vibrate in the opening and closing direction, a potential difference is generated in the piezoelectric element 80. The potential difference changes depending on whether the pair of arms 72a and 72b collide with each other. In addition, the potential difference also changes depending on whether the pair of arms 72a and 72b are in a resonant state. The detection unit 90b detects the change in the output current based on the change in the potential difference of the piezoelectric element 80. The detection unit 90b stores the data related to the detected output current in the memory of the wire bonding control unit 90.

[0077] The determination unit 90c obtains data related to the output current stored in the memory, and determines the open and closed state of the pair of arm portions 72a and 72b based on the generation status of the harmonic component of the resonance frequency fr in the output current. When the pair of arm portions 72a and 72b are in the open state, if an AC voltage of the resonance frequency fr is applied to the piezoelectric element 80, as the output current, in addition to the fundamental wave component of the resonance frequency fr, the harmonic component is also detected. When the pair of arm portions 72a and 72b become the closed state, the harmonic component of the resonance frequency fr contained in the output current becomes very small or substantially zero. Using this situation, the determination unit 90c determines the open and closed state of the pair of arm portions 72a and 72b.

[0078] Specifically, by changing the voltage of the DC component while setting the frequency of the AC component of the driving voltage to the resonance frequency fr in the supply unit 90a, the open and closed states of the pair of arms 72a and 72b are determined in the determination unit 90c based on the presence and intensity of harmonic components in the output current.

[0079] At this time, the determination unit 90c performs Fourier transformation on the output current, and calculates the intensity of the fundamental wave component of the resonance frequency fr, and the intensity of the harmonic component of the resonance frequency fr. Here, the harmonic component of the resonance frequency fr may include a plurality of higher harmonics including the second harmonic f2 of the resonance frequency fr, for example, components including 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 of the resonance frequency fr to the fundamental wave component, and calculates the rate of change of the intensity ratio relative to the voltage change of the DC component in the driving voltage. Then, when the rate of change of the intensity ratio exceeds the threshold value, the determination unit 90c determines that the open state and the closed state of the pair of arm portions 72a and 72b have been switched.

[0080] The intensity of the harmonic component is smaller than that of the fundamental wave component, so the determination unit 90c improves the determination accuracy by making a determination based on the intensity ratio relative to the rate of change of the voltage change. However, as long as the determination unit 90c can determine the open and closed state of the pair of arm portions 72a, 72b, the determination may be made based on the intensity ratio of the harmonic component to the fundamental wave component, or based on the intensity of the harmonic component.

[0081] In order to determine the resonance frequency fr used in the step of determining the open and closed state of the pair of arm portions 72a and 72b, the determination unit may determine the resonance state of the pair of arm portions 72a and 72b. For example, the determination unit 90c determines the resonance state of the pair of arm portions 72a and 72b based on the generation status of the component caused by the collision of the pair of arm portions 72a and 72b in the output current detected by the detection unit 90b. In the case where the pair of arm portions 72a and 72b in the open state vibrate and collide with each other, in addition to the component caused by the AC component of the driving voltage of the pair of arm portions 72a and 72b, the output current also includes a component caused by the mutual collision of the pair of arm portions 72a and 72b (hereinafter referred to as a "collision component"). Using this situation, the determination unit 90c determines the resonance state of the pair of arm portions 72a and 72b.

[0082] Specifically, in the supply unit 90a, the frequency of the AC component of the driving voltage is changed in a state where the voltages of the DC component and the AC component of the driving voltage are set, so that the pair of arm portions 72a and 72b collide with each other when vibrating in a resonant state, and do not collide with each other when vibrating in a non-resonant state. Then, in the determination unit 90c, the opening and closing state of the pair of arm portions 72a and 72b is determined based on the presence and intensity of the collision component in the output current.

[0083] At this time, the determination unit 90c performs Fourier transformation on the output current and calculates 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, it is about 5 times the height of 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 the threshold value, the determination unit 90c determines that the pair of arm portions 72a, 72b vibrates in a resonant state.

[0084] The registering unit 90d registers the voltage of the DC component of the driving voltage when the pair of arms 72a and 72b are switched between the open state and the closed state as a reference voltage based on the determination result of the determination unit 90c on the open and closed state of the pair of arms 72a and 72b. Here, the reference voltage when the pair of arms 72a and 72b are in contact with each other in the closed state refers to a DC voltage equivalent to the state (load zero point) of contacting each other in the state where the wire clamping load is substantially zero. In addition, the reference voltage when the pair of arms 72a and 72b are clamping the wire or the correction fixture with higher dimensional accuracy than the wire in the closed state refers to a DC voltage equivalent to the state (load zero point) of clamping the wire or the correction fixture in the state where the wire clamping load is substantially zero. Such a reference voltage may be, for example, a reference voltage when the pair of arms 72a and 72b are switched from the open state to the closed state, or a reference voltage when the pair of arms 72a and 72b are switched from the closed state to the open state. In addition, below, the time when switching from the open state to the closed state is referred to as “ending closing”, and the time when switching from the closed state to the open state is referred to as “starting opening”.

[0085] The registering unit 90d registers at least one of the reference voltage for ending closing and the reference voltage for starting opening when the pair of arms 72a and 72b are in contact with each other in the closed state, and the reference voltage for ending closing and the reference voltage for starting opening when the pair of arms 72a and 72b clamp the wire or the correction fixture. The relationship between the voltage applied to the pair of arms 72a and 72b and the opening and closing amount represents hysteresis. That is, the reference voltage for ending closing and the reference voltage for starting opening become different values ​​from each other, so it is ideal that the registering unit 90d registers both the reference voltage for ending closing and the reference voltage for starting opening. The registering unit 90d also calculates the change rate of the opening and closing amount of the pair of arms 72a and 72b relative to the voltage applied to the piezoelectric element 80 on the basis of the reference voltage and registers it. The data registered by the registering unit 90d is stored in the memory of the wire bonding control unit 90. In addition, an example of calculating the reference voltage and the change rate of the opening and closing amount in the registering unit 90d will be described later.

[0086] The calibration unit 90e reads data related to 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 use voltage (DC voltage) applied to the piezoelectric element 80 during the wire bonding process. In this case, the calibration unit 90e may correct the value of the set use voltage, or may newly set the use voltage to be applied to the piezoelectric element 80. In this way, the use voltage calibrated by the calibration unit 90e is stored in the memory of the wire bonding control unit 90. In addition, the supply unit 90a may read the calibrated use voltage stored in the memory during the wire bonding process, and drive the piezoelectric element 80 based on the use voltage.

[0087] <Calibration method>

[0088] Next, refer to Figure 5 to Figure 12 A calibration method using the wire clamping device 70 of the present embodiment will be described. Figure 5 : is a flowchart showing a method of registering a resonance frequency. Figure 6 This is a graph obtained by Fourier transforming the output current when the tip of the arm collides. Figure 7 , Figure 8 This is a flowchart showing a part of the calibration method of the wire clamping device according to the embodiment of the present invention. Figure 7 , Figure 8 This is a flowchart showing a method of registering the reference voltage and the rate of change of the opening and closing amount when the pair of arm portions 72 a and 72 b start to open. Fig. 9 This is a graph obtained by Fourier transforming the output current immediately before the arm starts to open. Fig.10 This is a graph obtained by Fourier transforming the output current immediately after the arm portion is in the open state when the arm portion starts to open. Fig.11 , Fig.12 This is a flowchart showing a part of the calibration method of the wire clamping device according to the embodiment of the present invention. Fig.11 , Fig.12 1 is a flowchart showing a method for registering the reference voltage and the rate of change of the opening and closing amount when the pair of arm portions 72a and 72b finish closing. Figure 6 , Fig. 9 and Fig.10 The graph shown is a graph obtained by subjecting data obtained by sampling the output current at 100 kSPS through a current detection circuit and performing Fast Fourier Transform (FFT) processing, wherein the horizontal axis represents frequency and the vertical axis represents intensity.

[0089] The calibration method of this embodiment can be performed using the wire bonding apparatus 1. The calibration method of the wire clamping apparatus 70 of this embodiment can be performed at the end of wire bonding (ie, before the next wire bonding starts) or during teaching for wire bonding.

[0090] In the calibration method of one aspect of the present invention, the resonance frequency fr of the pair of arm portions 72a and 72b is used. Therefore, in the case where the resonance frequency fr changes due to mechanical error or time change, it is desirable to register the resonance frequency fr immediately before calibration. Figure 5 A method for registering the resonance frequency fr of the pair of arm portions 72a and 72b will be described. Figure 6As shown, whether the pair of arm portions 72a, 72b vibrates at the resonance frequency fr is determined based on the generation state of the collision component at the frequency fx. If the resonance frequency fr is determined, the step of registering the resonance frequency fr may be omitted.

[0091] First, in the driving voltage, the voltage of the DC component is set to a voltage at which the pair of arm portions 72a and 72b are in an open state, and the frequency of the AC component is arbitrarily set (S11). At this time, the voltage of the AC component of the driving voltage is set to a size that the pair of arm portions 72a and 72b collide with each other when vibrating in a resonant state, and do 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.

[0092] Next, the frequency of the AC component in the driving voltage is changed (S12). The supply unit 90a changes the frequency of the AC component within a frequency range including the assumed 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 units of 0.05 kHz. Then, the output current at each frequency is detected (S13).

[0093] Next, the resonance state at each frequency is determined based on the output current (S14). Figure 6 The intensity of the frequency fx of the collision component shown is used to determine. When the frequency fx of the collision component exceeds the threshold value, it is determined that the pair of arm portions 72a and 72b are in a resonant state. Then, the frequency of the AC component in the driving voltage when the resonant state becomes the 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 becomes the strongest is registered as the resonant frequency fr. In addition, when there is only one frequency of the AC component determined to be in a resonant state in step S14, the frequency of the 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 through the registration unit 90d. The resonant frequency fr is, for example, 2.45kHz.

[0094] Next, refer to Figure 7 A method for registering a reference voltage for starting to open when a pair of arms 72a and 72b are not clamping anything will be described. Fig. 9 and Fig.10As shown, whether a pair of arm portions 72a, 72b are in an open or closed state is determined based on the generation conditions of harmonic components near the frequency f2 (f2≒fr×2) of the second harmonic of the resonance frequency fr, near the frequency f3 (f3≒fr×3) of the third harmonic, and near the frequency f4 (f4≒fr×4) of the fourth harmonic when a driving voltage including an AC component of the resonance frequency fr is applied.

[0095] First, the frequency of the AC component in the driving voltage is set to the resonant frequency fr, and the voltage of the DC component is set to the voltage at which the pair of arm portions 72a and 72b are in the closed state (S21). The resonant frequency fr used here is the resonant frequency 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 assumed reference voltage. For example, the voltage of the DC component is set to 40V, and the voltage of the AC component is set to 8V.

[0096] Next, the output current is detected, and the intensity ratio of the harmonic component of the resonance frequency fr to the fundamental component is calculated (S22). The output current detected by the current detection circuit in the detection unit 90b is Fourier transformed, and the peak intensity near 1 times (fundamental wave), 2 times (second harmonic f2), 3 times (third harmonic f3), and 4 times (fourth harmonic f4) of the resonance frequency fr is calculated. The intensity of the harmonic component is set to the sum of the intensities of the second harmonic, the third harmonic, and the fourth harmonic. The intensity ratio is calculated by dividing the intensity of the harmonic component by the intensity of the fundamental component.

[0097] In addition, the order of the harmonic contained in the intensity of the harmonic component is not limited to the above. It may not include the intensity of any harmonic from the second to fourth order, and may include the intensity of harmonics above the fifth order. In addition, the intensity of the harmonic component may also be the intensity of a harmonic of one order.

[0098] Next, the voltage of the DC component in the driving voltage is increased by one stage (S23). If the increase in the voltage of the DC component is too small, the change in the intensity of the harmonic component is too small and the determination accuracy of the reference voltage is reduced. If the increase in the voltage of the DC component is too large, the error of the reference voltage becomes large. Therefore, in step S23, the change in the voltage of the DC component increased by the supply unit 90a is ideally about 1V. However, the increase in the voltage of the DC component is not limited to the above, and can be about 0.5V or about 1.5V.

[0099] Next, the output current is detected and the intensity ratio of the harmonic component of the resonance frequency fr to the fundamental component is calculated (S24). As in step S22, the intensity of the harmonic component is divided by the intensity of the fundamental component to calculate the intensity ratio.

[0100] Next, it is determined whether the rate of change of the intensity ratio exceeds a threshold value (S25). The rate of change of the intensity ratio is calculated by dividing the intensity ratio calculated in step S24 by the intensity ratio calculated in step S22. When the rate of change of the intensity ratio exceeds the threshold value, it is determined that the pair of arms 72a, 72b is switched from the closed state to the open state. The threshold value is, for example, a value set in advance, for example, an arbitrary value set to be greater than 10% and less than 60%.

[0101] In addition, the threshold value of the rate of change of the intensity ratio may also be a value determined during calibration. For example, the threshold value may also be determined based on the average value, maximum value, or central value of the rate of change of the intensity ratio when the voltage of the DC component is increased by an arbitrary number of steps while the pair of arms 72a, 72b are definitely in the closed state. For example, the threshold value may also be set to a multiple of 2 or 3 times the average value, maximum value, or central value of the rate of change of the intensity ratio.

[0102] When the rate of change of the intensity ratio does not exceed the threshold value (S25 is NO), the process returns to step S23, and the voltage of the DC component in the driving voltage is further increased by one stage. In step S24, the intensity ratio of the harmonic component of the resonance frequency fr to the fundamental component is calculated. Then, in step S25, the rate of change of the intensity ratio before and after the change of the voltage of the DC component is calculated to determine whether it exceeds the threshold value. In this way, the calculation of the rate of change of the intensity ratio when the voltage of the DC component is increased by 1V is repeated. When it is determined that the rate of change of the intensity ratio exceeds the threshold value (S25 is YES), based on the determination result, the voltage of the DC component before the increase is registered as the reference voltage for starting to open (S26).

[0103] exist Fig. 9 In the example shown, 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%. In addition, the change rate of the intensity ratio when the voltage of the DC component is increased from 65V to 66V is about -3.038%. Fig.10In the example shown, the voltage of the DC component is 67V, and the intensity ratio of the harmonic component to the fundamental component is about 6.138%. The rate of change of 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 arms 72a, 72b is switched from the closed state to the open state, the rate of change of the intensity ratio becomes much larger than the previous rate of change. By the way, the intensity ratio is about 2.935% when the voltage of the DC component is 40V, and the intensity ratio is about 3.199% when it is 41V. The rate of change of the intensity ratio when the voltage of the DC component is increased from 40V to 41V is about 8.988%. In the range where the pair of arms 72a, 72b is in the closed state, the intensity ratio is small, so it is easily affected by noise, etc. The rate of change of the intensity ratio can take any value of positive value or negative value, but the rate of change of the intensity ratio when the pair of arms 72a, 72b is switched from the closed state to the open state is a large positive value.

[0104] Next, refer to Figure 8 The method of registering the reference voltage for starting opening and the rate of change of the opening and closing amount when the pair of arms 72a and 72b clamp the calibration jig will be described. In addition, the description of the same operations as those described in steps S21 to S26 will be omitted as appropriate.

[0105] First, the calibration jig is placed between the pair of arms 72a and 72b (S31), and the reference voltage for starting to open the calibration jig when the calibration jig is clamped is registered (S32). In step S32, steps S21 to S26 are executed.

[0106] Next, the voltage difference of the reference voltage for starting to open caused by the presence or absence of the correction fixture is calculated (S33). The reference voltage for starting to open is different when the pair of arms 72a, 72b are not clamped with any object and when the correction fixture is clamped. The reason is that when the correction fixture is clamped, the pair of arms 72a, 72b in the closed state are separated from each other by an amount corresponding to the size of the correction fixture in the opening and closing direction of the pair of arms 72a, 72b. The reference voltage for starting to open when the correction fixture is clamped is greater than the reference voltage for starting to open when no object is clamped. Therefore, the voltage difference of the reference voltage for starting to open is calculated by subtracting the reference voltage for starting to open when no object is clamped registered in step S26 from the reference voltage for starting to open when the correction fixture is clamped registered in step S32.

[0107] Next, the rate of change of the opening and closing amount of the pair of arm portions 72a, 72b relative to the applied voltage when the pair of arm portions 72a, 72b start to open is calculated (S34). The voltage difference calculated in step S33 is equivalent to the applied voltage added to the piezoelectric element 80 when the opening and closing amount of the pair of arm portions 72a, 72b is changed by an amount corresponding to the size of the correction fixture in the opening and closing direction. Here, the opening and closing amount of the pair of arm portions 72a, 72b is the distance between the clamping pieces 71a and the clamping pieces 71b in the opening and closing direction. The rate of change of the opening and closing amount of the pair of arm portions 72a, 72b relative to the applied voltage is calculated by dividing the size of the correction fixture in the opening and closing direction by the voltage difference calculated in step S33.

[0108] Next, the change rate of the opening and closing amount of the pair of arm portions 72a and 72b at the start of opening is registered (S35). The change rate of the opening and closing amount calculated in step S34 is stored in the memory of the wire bonding control unit 90.

[0109] Next, refer to Fig.11 A method of registering a reference voltage for ending closing when the pair of arm portions 72a and 72b do not clamp anything will be described. In addition, description of the same contents as those already described in step S21 to step S26 will be omitted as appropriate.

[0110] First, the frequency of the AC component in the driving voltage is set to the resonance frequency fr, and the voltage of the DC component is set to a voltage at which the pair of arm portions 72a and 72b are in an open state (S41). The difference between step S41 and step S21 is that the voltage of the DC component of the driving voltage is set to a voltage at which the pair of arm portions 72a and 72b are in an open state rather than a closed state. For example, the voltage of the DC component is set to 100V, and the voltage of the AC component is set to 5V.

[0111] Next, the output current is detected, and the intensity ratio of the harmonic component of the resonance frequency fr to the fundamental wave component is calculated (S42). Step S42 is the same as step S22.

[0112] Next, the voltage of the DC component in the driving voltage is decreased by one step (S43). The difference between step S43 and step S23 is that the voltage of the DC component is decreased instead of increased. The voltage change amount of the DC component in step S43 is the same as that in step S23, for example, about 1V.

[0113] Next, the output current is detected, and the intensity ratio of the harmonic component of the resonance frequency fr to the fundamental wave component is calculated (S44). Step S44 is the same as step S24.

[0114] Next, it is determined whether the rate of change of the intensity ratio exceeds a threshold value (S45), and based on the determination result, the voltage of the DC component before the decrease is registered as a reference voltage for ending the shutdown (S46). The difference between step S45 and step S25 is that the threshold value set is different, and the threshold value in step S45 is set to zero, for example.

[0115] Specifically, in the process of a pair of arms 72a, 72b approaching the closed state from the open state, the intensity of the harmonic component decreases, so the rate of change of the intensity ratio accompanying the voltage drop becomes a negative value. However, just after switching to the closed state, since the opening and closing states of the pair of arms 72a, 72b change, the balance between the input and the reaction changes, so the rate of change of the intensity ratio becomes a positive value. After the pair of arms 72a, 72b becomes the closed state, the rate of change of the intensity ratio randomly repeats positive and negative values. As an example, the intensity ratio when the voltage of the DC component is 57V is about 6.383%, and the rate of change of the intensity ratio when the voltage of the DC component is reduced from 58V to 57V is about -13.314%. The intensity ratio when the voltage of the DC component is 56V is about 5.303%, and the rate of change of the intensity ratio when the voltage of the DC component is reduced from 57V to 56V is about -16.933%. When the voltage of the DC component is 52V, the intensity ratio is about 3.540%, and the rate of change of the intensity ratio when the voltage of the DC component is reduced from 53V to 52V is about -22.834%. When the voltage of the DC component is 51V, the intensity ratio is about 3.591%, and the rate of change of the intensity ratio when the voltage of the DC component is reduced from 52V to 51V is about 1.420%. In the above case, when the voltage of the DC component is 52V, the pair of arm parts 72a and 72b complete the closing, and the intensity ratio does not decrease further. Therefore, even if the voltage of the DC component is reduced from 52V to 51V, the intensity ratio does not decrease. Therefore, the voltage 52V before the reduction when the rate of change of the intensity ratio becomes a positive value is registered as the reference voltage when the closing is completed.

[0116] In addition, the threshold value of the rate of change of the intensity ratio when the closing is completed is not limited to zero. For example, if the rate of change of the intensity ratio changes within the range, the threshold value can also be set to an arbitrary value greater than -10% and less than 1%. In addition, in the step of determining the open and closed state of the pair of arms 72a and 72b at the end of closing, the open and closed state can also be determined based on whether the absolute value of the rate of change of the intensity ratio is lower than the threshold. Specifically, when the absolute value of the rate of change of the intensity ratio is greater than the threshold, it can be determined that the pair of arms 72a and 72b are in the open state, and when the absolute value of the rate of change of the intensity ratio is less than the threshold, it can be determined that the pair of arms 72a and 72b are in the closed state. The reason is that when the pair of arms 72a and 72b are close to the closed state in the open state, the rate of change of the intensity ratio is large, but when the pair of arms 72a and 72b become the closed state, the intensity ratio does not change substantially, that is, the rate of change of the intensity ratio becomes smaller.

[0117] Next, refer to Fig.12 A method of registering the reference voltage for closing when the pair of arms 72a and 72b clamp the calibration jig and the rate of change of the opening and closing amount will be described. Note that description of operations similar to those described in steps S31 to S35 will be omitted as appropriate.

[0118] First, the calibration jig is placed between the pair of arms 72a and 72b (S51), and the reference voltage for closing the calibration jig when the calibration jig is clamped is registered (S52). In step S52, steps S41 to S46 are executed.

[0119] Next, the voltage difference of the reference voltage for closing the end caused by the presence or absence of the calibration fixture is calculated (S53). The voltage difference of the reference voltage for closing the end when no object is clamped is calculated by subtracting the reference voltage for closing the end when no object is clamped registered in step S46 from the reference voltage for closing the end when the calibration fixture is clamped registered in step S52.

[0120] Next, the change rate of the opening and closing amount of the pair of arm portions 72a and 72b with respect to the applied voltage when the pair of arm portions 72a and 72b finish closing is calculated (S54). Step S54 is the same as step S34.

[0121] Next, the change rate of the opening and closing amount of the pair of arm parts 72a and 72b at the time of closing is registered (S55). Step S55 is the same as step S35.

[0122] Finally, the operating voltage is calibrated (S36). The operating voltage is calibrated based on the registered reference voltage for the start of opening of the pair of arms 72a, 72b and the rate of change of the opening and closing amount at the start of opening, and the reference voltage for the end of closing and the rate of change of the opening and closing amount at the end of closing. By performing the wire bonding process with the wire clamping device 70 whose operating voltage is calibrated, the opening and closing actions of the pair of arms 72a, 72b of the wire clamping device 70 corresponding to the operating voltage can be accurately grasped. Therefore, a high-precision and stable wire bonding process can be performed.

[0123] This calibration method is preferably performed each time the wire bonding process is different, for example, when performing wire bonding with different wire diameters or when performing wire bonding in different temperature environments. This is particularly effective because calibration can be performed based on the ease of opening of the wire clamp 70 corresponding to each situation.

[0124] In addition, in steps S31 to S35 and steps S51 to S55, a predetermined wire 42 to be wire-bonded after calibration may be used instead of the calibration jig.

[0125] Hereinafter, some or all of the embodiments of the present invention will be supplemented. In addition, the present invention is not limited to the following supplementary notes.

[0126] [Note 1]

[0127] A clamping device 70 includes: a pair of arms 72a, 72b, which clamp a wire 42; a driving unit 76, which has a piezoelectric element 80 that opens / closes the pair of arms 72a, 72b; a supply unit 90a, which is configured to generate a driving voltage superimposed with a frequency-variable AC component and a voltage-variable DC component and is capable of supplying the driving voltage to the piezoelectric element 80, and increase or decrease the voltage of the DC component in a state where the frequency of the AC component is set to the resonant frequency of the pair of arms 72a, 72b; a detection unit 90b, which detects an output signal output from the driven piezoelectric element 80; and a determination unit 90c, which determines the open / closed state of the pair of arms 72a, 72b based on the generation of the harmonic component of the resonant frequency in the output signal.

[0128] According to [Note 1], since the opening and closing states of a pair of arms 72a and 72b are determined based on the generation of harmonic components in the output signal, the influence of mechanical errors such as the ease of vibration, the ease of vibration transmission, and the ease of output signal detection can be reduced in the determination of the opening and closing states.

[0129] [Note 2]

[0130] The clamping device described in [Note 1] also includes: a registration unit 90d, which registers the DC component voltage when a pair of arm portions 72a and 72b are switched between the open state and the closed state as a reference voltage; and a calibration unit 90e, which calibrates the operating voltage applied to the piezoelectric element 80 based on the reference voltage.

[0131] According to the aspect of [Supplementary Note 2], it is possible to perform high-precision calibration based on the high-precision determination result of the open / closed state, thereby achieving improved precision and stabilization of the opening / closing operation of the clamp device 70 .

[0132] [Note 3]

[0133] The clamping device 70 according to [Supplementary Note 2], wherein the detection unit 90b detects an output current output from the piezoelectric element 80 as an output signal.

[0134] According to the form of [Supplementary Note 3], the output current from the pair of arm portions 72a, 72b can be represented by the time differential of the output voltage, so even a change in magnitude that is difficult to detect as an output voltage can sometimes become a change in magnitude that can be detected as an output current. Therefore, the detection accuracy of the detection unit 90b can be improved, and the accuracy of calibration can be improved.

[0135] [Note 4]

[0136] The clamping device 70 according to [Supplementary Note 3], wherein the determination unit 90c calculates the intensity of the harmonic component of the resonance frequency in the output signal by performing Fourier transform on the output current.

[0137] According to the aspect of [Supplementary Note 4], the components included in the output signal can be separated based on the frequency, and the intensity of each component can be compared.

[0138] [Note 5]

[0139] The clamping device 70 according to [Supplementary Note 4], wherein the determination unit 90c calculates an intensity ratio of a harmonic component of the resonance frequency in the output signal to a fundamental wave component.

[0140] According to the aspect of [Supplementary Note 5], the open / closed state can be determined based on the intensity ratio of the harmonic components that are more susceptible to noise and are more easily compared, thereby improving the determination accuracy.

[0141] [Note 6]

[0142] The clamping device 70 according to [Supplementary Note 5], wherein the determination unit 90c calculates a rate of change of the intensity ratio with respect to a voltage change of the DC component.

[0143] According to the aspect of [Supplementary Note 6], the open / closed state can be determined based on the rate of change of the intensity ratio which is more easily affected by noise than the intensity ratio which is more easily compared, thereby improving the determination accuracy.

[0144] [Note 7]

[0145] According to the clamping device 70 described in [Supplementary Note 6], the registration unit 90d registers the first voltage as the reference voltage when the rate of change of the intensity ratio when the voltage of the DC component is changed from the first voltage to the second voltage exceeds a threshold value.

[0146] According to the form of [Supplementary Note 7], when the pair of arms 72a and 72b switch between the open state and the closed state, the change rate of the intensity ratio changes significantly, so the first voltage when the change rate of the intensity ratio exceeds the threshold value can be set as the reference voltage.

[0147] [Note 8]

[0148] A clamping device 70 according to any one of [Note 2] to [Note 7], wherein the registration unit 90d registers a DC component voltage when a pair of arms 72a, 72b are switched from a closed state to an open state as a reference voltage for starting to open the pair of arms 72a, 72b, and registers a DC component voltage when a pair of arms 72a, 72b are switched from an open state to a closed state as a reference voltage for finishing closing the pair of arms 72a, 72b, when the pair of arms 72a, 72b are in contact with each other in a closed state.

[0149] According to the form of [Note 8], by registering both the reference voltage for starting to open and the reference voltage for ending to close, the voltage used when a pair of arms 72a, 72b are opened and the voltage used when they are closed can be calibrated, thereby achieving further improvement in the accuracy and stabilization of the opening and closing action.

[0150] [Note 9]

[0151] According to the clamping device 70 described in any one of [Note 2] to [Note 7], wherein the registration unit 90d registers the DC component voltage when the pair of arms 72a, 72b are switched from the closed state to the open state as a reference voltage for the pair of arms 72a, 72b to start opening, and registers the DC component voltage when the pair of arms 72a, 72b are switched from the open state to the closed state as a reference voltage for the pair of arms 72a, 72b to finish closing, when the pair of arms 72a, 72b are clamped in the closed state with a correction fixture having a higher dimensional accuracy than the conductor 42.

[0152] According to the form of [Supplementary Note 9], by registering both the reference voltage for opening and the reference voltage for closing when the calibration jig is clamped, the voltage used when the pair of arms 72a, 72b is opened and the voltage used when closed can be calibrated, thereby further improving and stabilizing the accuracy of the opening and closing operation. By clamping the calibration jig having a higher dimensional accuracy than the conductor 42 when obtaining the reference voltage, the calibration accuracy can be improved compared to the case where the conductor 42 is clamped.

[0153] [Note 10]

[0154] According to the clamping device 70 described in any one of [Note 2] to [Note 7], wherein the registration unit 90d registers the DC component voltage when the pair of arms 72a, 72b are switched from the closed state to the open state as a reference voltage for the pair of arms 72a, 72b to start opening, and registers the DC component voltage when the pair of arms 72a, 72b are switched from the open state to the closed state as a reference voltage for the pair of arms 72a, 72b to finish closing, when the pair of arms 72a, 72b are clamped in the closed state.

[0155] According to the form of [Supplementary Note 10], by registering both the reference voltage for opening and the reference voltage for closing when clamping the conductor 42, the voltage used when the pair of arms 72a and 72b are opened and the voltage used when they are closed can be calibrated, thereby further improving and stabilizing the accuracy of the opening and closing operation. By clamping the workpiece when obtaining the reference voltage, the structure of the clamping device and the calibration work can be simplified compared to the case of clamping the calibration fixture.

[0156] [Note 11]

[0157] According to the clamping device 70 described in any one of [Note 2] to [Note 7], wherein the registration unit 90d registers the DC component voltage when the pair of arms 72a, 72b are switched between the open state and the closed state as a first reference voltage when the pair of arms 72a, 72b are in contact with each other in the closed state, and registers the DC component voltage when the pair of arms 72a, 72b are switched between the open state and the closed state as a second reference voltage when the pair of arms 72a, 72b are clamped in the closed state to a correction fixture or a conductor 42 having a higher dimensional accuracy than the conductor 42, and calculates and registers the rate of change of the opening and closing amount of the pair of arms 72a, 72b relative to the voltage applied to the piezoelectric element 80 based on the voltage difference between the first reference voltage and the second reference voltage and the size of the correction fixture or the conductor 42 in the opening and closing direction of the pair of arms 72a, 72b, and the calibration unit 90e calibrates the use voltage applied to the piezoelectric element 80 based on the rate of change of the opening and closing amount.

[0158] According to the embodiment of [Supplement 11], by also calibrating the opening and closing amounts of the pair of arm portions 72a and 72b with respect to the operating voltage, it is possible to further improve and stabilize the accuracy of the opening and closing operation.

[0159] [Note 12]

[0160] The clamping device 70 according to any one of [Supplementary Note 1] to [Supplementary Note 11], wherein the harmonic component of the resonance frequency includes a plurality of harmonic components.

[0161] According to the aspect of [Supplement 12], the accuracy of determining the opening and closing state of the pair of arms 72a and 72b based on the harmonic component is improved, so the accuracy of calibration is improved, and further improvement and stabilization of the accuracy of the opening and closing operation can be achieved.

[0162] [Note 13]

[0163] A clamping device 70 according to any one of [Note 1] to [Note 12], wherein the supply unit 90a increases or decreases the frequency of the AC component when the voltage of the DC component is set to a voltage at which a pair of arms 72a, 72b are in an open state, the determination unit 90c determines the resonance state of the pair of arms 72a, 72b based on the generation condition of the component caused by the collision of the pair of arms 72a, 72b in the output signal, and the registration unit 90d registers the frequency of the AC component when the resonance state of the pair of arms 72a, 72b becomes the strongest as the resonance frequency of the pair of arms 72a, 72b.

[0164] According to the form of [Note 13], even if the resonance frequency changes due to mechanical errors or changes over time, the resonance frequency of a pair of arms 72a and 72b can be obtained before performing calibration, thereby improving the accuracy of calibration and achieving further improvement and stabilization of the accuracy of the opening and closing action.

[0165] [Note 14]

[0166] A control method is a control method for a clamping device 70, wherein the clamping device 70 includes: a pair of arms 72a, 72b, which clamp a wire 42; a driving unit 76, which has a piezoelectric element 80 that opens / closes the pair of arms 72a, 72b; and a supply unit 90a, which is configured to generate a driving voltage superimposed with a frequency-variable AC component and a voltage-variable DC component and can supply the driving voltage to the piezoelectric element 80. The control method of the clamping device 70 includes: increasing or decreasing the voltage of the DC component while setting the frequency of the AC component to the resonant frequency of the pair of arms 72a, 72b; detecting an output signal output from the driven piezoelectric element 80; and determining the open / closed state of the pair of arms 72a, 72b based on the generation of the harmonic component of the resonant frequency in the output signal.

[0167] According to the form of [Note 14], since the opening and closing states of a pair of arms 72a and 72b are determined based on the generation of harmonic components in the output signal, the influence of mechanical errors such as the ease of vibration, the ease of vibration transmission, and the ease of detection of the output signal can be reduced in the determination of the opening and closing states.

[0168] [Note 15]

[0169] A control program is a control program for operating a clamping device 70, wherein the clamping device 70 includes: a pair of arms 72a, 72b, which clamp a wire 42; a driving unit 76, which has a piezoelectric element 80 for opening / closing the pair of arms 72a, 72b; and a supply unit 90a, which is configured to generate a driving voltage superimposed with a frequency-variable AC component and a voltage-variable DC component and can supply the driving voltage to the piezoelectric element 80, wherein the control program causes a computer to execute: increasing or decreasing the voltage of the DC component while setting the frequency of the AC component to the resonant frequency of the pair of arms 72a, 72b; detecting an output signal output from the driven piezoelectric element 80; and determining the open / closed state of the pair of arms 72a, 72b based on the generation of the harmonic component of the resonant frequency in the output signal.

[0170] According to the form of [Note 15], since the opening and closing states of a pair of arms 72a and 72b are determined based on the generation of harmonic components in the output signal, the influence of mechanical errors such as the ease of vibration, the ease of vibration transmission, and the ease of output signal detection can be reduced in the determination of the opening and closing states.

[0171] As described above, according to one aspect of the present invention, it is possible to improve the accuracy of determining the open and closed states of a pair of arms.

[0172] 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 various components and their configurations, materials, conditions, shapes, and sizes included in the embodiments are not limited to the illustrated contents and may be appropriately changed. In addition, the structures shown in different embodiments may be partially replaced or combined with each other.

[0173] Description of Figure Numbers

[0174] 1: Wire bonding device

[0175] 70: Wire clamping device

[0176] 72a, 72b: Arm

[0177] 73a, 73b: Front end

[0178] 74a, 74b: base end

[0179] 76: Drive unit

[0180] 90: Wire bonding control unit

[0181] 90a: Supply Department

[0182] 90b: Detection Department

[0183] 90c: Judgment Department

[0184] 90d: Registration Department

[0185] 90e: Calibration Department

Claims

1. A clamping device, comprising: A pair of arms for clamping the object to be processed; a driving unit having a piezoelectric element for opening / closing the pair of arm portions; a supply unit configured to generate a driving voltage superimposed with a frequency-variable AC component and a voltage-variable DC component and capable of supplying the driving voltage to the piezoelectric element, and to increase or decrease the voltage of the DC component in a state where the frequency of the AC component is set to the resonance frequency of the pair of arms; a detection unit for detecting an output signal output from the driven piezoelectric element; as well as The determination unit determines the open / closed state of the pair of arms based on a generation status of a harmonic component of the resonance frequency in the output signal.

2. The clamping device according to claim 1, further comprising: a registering unit that registers the voltage of the DC component when the open state and the closed state of the pair of arms are switched as a reference voltage; as well as The calibration unit calibrates a use voltage applied to the piezoelectric element based on the reference voltage.

3. The clamping device according to claim 2, wherein: The detection unit detects an output current output from the piezoelectric element as the output signal.

4. The clamping device according to claim 3, wherein: The determination unit calculates the intensity of the harmonic component of the resonance frequency in the output signal by performing Fourier transform on the output current.

5. The clamping device according to claim 4, wherein: The determination unit calculates an intensity ratio of a harmonic component of the resonance frequency to a fundamental wave component in the output signal.

6. The clamping device according to claim 5, wherein: The determination unit calculates a rate of change of the intensity ratio with respect to a change in voltage of the DC component.

7. The clamping device according to claim 6, wherein: The registration unit registers the first voltage as a reference voltage when a change rate of the intensity ratio when changing the voltage of the DC component from the first voltage to the second voltage exceeds a threshold value.

8. The clamping device according to claim 2, wherein: The registration department When the pair of arms are in contact with each other in the closed state, registering the voltage of the DC component when the pair of arms are switched from a closed state to an open state as a reference voltage for starting to open the pair of arms, The voltage of the DC component when the pair of arms is switched from the open state to the closed state is registered as a reference voltage when the pair of arms finish closing.

9. The clamping device according to claim 2, wherein: The registration department When the pair of arms are in a closed state, they clamp a calibration fixture having a higher dimensional accuracy than the object to be processed. registering the voltage of the DC component when the pair of arms are switched from a closed state to an open state as a reference voltage for starting to open the pair of arms, The voltage of the DC component when the pair of arms is switched from the open state to the closed state is registered as a reference voltage when the pair of arms finish closing.

10. The clamping device according to claim 2, wherein: The registration department When the pair of arms are in a closed state and clamp the object to be processed, registering the voltage of the DC component when the pair of arms are switched from a closed state to an open state as a reference voltage for starting to open the pair of arms, The voltage of the DC component when the pair of arms is switched from the open state to the closed state is registered as a reference voltage when the pair of arms finish closing.

11. The clamping device according to claim 2, wherein: The registration department When the pair of arms are in contact with each other in the closed state, the voltage of the DC component when the pair of arms are switched between the open state and the closed state is registered as a first reference voltage, When the pair of arms are in a closed state and clamp a calibration fixture or the object to be processed with a higher dimensional accuracy than the object to be processed, the voltage of the DC component when the pair of arms are switched between the open state and the closed state is registered as a second reference voltage. Based on the voltage difference between the first reference voltage and the second reference voltage and the size of the calibration fixture or the object to be processed in the opening and closing direction of the pair of arms, the rate of change of the opening and closing amount of the pair of arms relative to the voltage applied to the piezoelectric element is calculated and registered, The calibration unit calibrates a use voltage applied to the piezoelectric element based on a change rate of the opening and closing amount.

12. The clamping device according to claim 1, wherein: The harmonic component of the resonance frequency includes a plurality of harmonic components.

13. The clamping device according to claim 2, wherein: The supply unit 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 arms are in an open state. The determination unit determines the resonance state of the pair of arms based on a generation condition of a component caused by a collision of the pair of arms in the output signal. The registration unit registers the frequency of the AC component when the resonance state of the pair of arms becomes the strongest as the resonance frequency of the pair of arms.

14. A control method is a control method for a clamping device, the clamping device comprising: A pair of arms for clamping the object to be processed; a driving unit having a piezoelectric element for opening / closing the pair of arm portions; as well as The supply unit is configured to generate a driving voltage superimposed with a frequency-variable AC component and a voltage-variable DC component and to supply the driving voltage to the piezoelectric element. The control method of the clamping device includes: increasing or decreasing the voltage of the DC component while setting the frequency of the AC component to the resonance frequency of the pair of arms; detecting an output signal output from the driven piezoelectric element; as well as The open / closed state of the pair of arms is determined based on a generation condition of a harmonic component of the resonance frequency in the output signal.

15. A control program is a control program for operating a clamping device, the clamping device comprising: A pair of arms for clamping the object to be processed; a driving unit having a piezoelectric element for opening / closing the pair of arm portions; as well as The supply unit is configured to generate a driving voltage on which a frequency-variable AC component and a voltage-variable DC component are superimposed and to supply the driving voltage to the piezoelectric element, wherein the control program causes the computer to execute: increasing or decreasing the voltage of the DC component while setting the frequency of the AC component to the resonance frequency of the pair of arms; detecting an output signal output from the driven piezoelectric element; as well as The open / closed state of the pair of arms is determined based on a generation condition of a harmonic component of the resonance frequency in the output signal.

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