WIRE BONDING APPARATUS, CONTROL METHOD FOR WIRE BONDING APPARATUS, AND CONTROL PROGRAM FOR WIRE BONDING APPARATUS

Abstract

The present invention provides a wire bonding device that can prevent bonding from being performed in a state in which a free air ball is eccentric.　This wire bonding device is provided with a capillary that supplies a bonding wire, a torch that forms a free air ball on a wire tail of the bonding wire fed from the capillary, an imaging unit that captures an image of the wire tail with the free air ball formed at an end thereof by the torch, and a measuring unit that measures, on the basis of the image output from the imaging unit, the eccentricity of the free air ball with respect to the central axis of the bonding wire.

Description

[Technical Field]

[0001] The present invention relates to a wire bonding apparatus, a control method for a wire bonding apparatus, and a control program for a wire bonding apparatus. [Background technology]

[0002] It is important to stabilize the shape of the free air ball (FAB) in a wire bonding device. For example, according to Patent Document 1, a stable FAB is formed by devising the composition of the bonding wire. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5807992 Summary of the Invention [Problem to be solved by the invention]

[0004] There are many different bonding wires used in wire bonding equipment, and they are often selected according to the purpose. Therefore, being limited to bonding wires with a specific composition is a major constraint. In addition to composition, factors such as environmental temperature, wire diameter, and tail length can also affect the eccentricity of free air balls relative to the wire axis. Eccentricity of free air balls can cause eccentricity of the compressed ball, which can lead to defects such as short circuits between pad electrodes.

[0005] The present invention has been made to solve such problems, and provides a wire bonding apparatus and the like that can prevent bonding from being performed with a free air ball that is off-center. [Means for solving the problem]

[0006] A wire bonding apparatus in a first aspect of the present invention includes a capillary for supplying bonding wire, a torch for forming a free air ball on the wire tail of the bonding wire unwound from the capillary, an imaging unit for imaging the wire tail with a free air ball formed at its tip by the torch, and a measurement unit for measuring the deviation of the free air ball relative to the central axis of the bonding wire based on the image output from the imaging unit.

[0007] A control method for a wire bonding apparatus in a second aspect of the present invention includes a tail forming step of unwinding a bonding wire from the tip of a capillary to form a wire tail, a free air ball forming step of forming a free air ball at the tip of the wire tail using a torch, an imaging step of imaging the wire tail on which the free air ball has been formed, and a measurement step of measuring the deviation of the free air ball relative to the central axis of the bonding wire based on the image output in the imaging step.

[0008] A control program for a wire bonding apparatus in a third aspect of the present invention causes a computer to execute a tail forming step of unwinding a bonding wire from the tip of a capillary to form a wire tail, a free air ball forming step of forming a free air ball at the tip of the wire tail using a torch, an imaging step of imaging the wire tail on which the free air ball has been formed, and a measurement step of measuring the deviation of the free air ball relative to the central axis of the bonding wire based on the image output in the imaging step. [Effects of the Invention]

[0009] According to the wire bonding apparatus and the like of the present invention, a free air ball can be formed in the manufacturing environment where semiconductor chips are actually manufactured, and its eccentricity can be immediately measured, so that bonding can be prevented from being performed with the free air ball in an eccentric state. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view schematically showing a main part of a wire bonder according to an embodiment of the present invention. [Figure 2] FIG. 1 is a system configuration diagram of a wire bonder. [Figure 3] FIG. 1 is a diagram illustrating the observation conditions of FAB. [Figure 4] FIG. 10 is a diagram illustrating a first method for measuring the bias of a FAB. [Figure 5] FIG. 10 is a diagram illustrating a second method for measuring the bias of a FAB. [Figure 6] FIG. 1 is a flowchart illustrating a processing procedure of a first example including FAB measurement according to the present embodiment. [Figure 7] FIG. 10 is a flowchart illustrating a processing procedure of a second example including FAB measurement according to the present embodiment. [Figure 8] FIG. 10 is a flowchart illustrating a processing procedure of a third example including FAB measurement according to the present embodiment. [Figure 9] FIG. 10 is a perspective view schematically showing a main part of a wire bonder according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described below through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential as means for solving the problems.

[0012] 1 is a perspective view showing a schematic diagram of a main part of a wire bonder 100 according to this embodiment. The illustrated wire bonder 100 uses simplified structures and mechanisms for easier understanding, has different element sizes and shapes, and omits elements that are not directly related to this embodiment, but is not intended to show any differences from an actual wire bonder.

[0013] The wire bonder 100 is a bonding device that connects a pad electrode 321 of a semiconductor chip 320 and a lead electrode 322 of a substrate 330 with a bonding wire 300. The wire bonder 100 mainly comprises a head unit 110, a tool unit 120, a torch 131, a capillary 133, a first imaging unit 151, and a second imaging unit 152. The head unit 110 supports the tool unit 120, the torch 131, the first imaging unit 151, and the second imaging unit 152, and is movable in a planar direction by a head drive motor 141. As shown in the figure, the planar direction is the horizontal direction defined by the X-axis and Y-axis directions, and is also the direction of movement of a stage 220 placed on a stand 210. A substrate 330 is placed and fixed on the stage 220.

[0014] The tool unit 120 supports a clamper 132 and a transducer 134, which extend in the Y-axis direction. A capillary 133 is attached to the tip of the transducer 134. The clamper 132 has a hand that clamps the wire 300 and grips and releases the wire 300 under the control of the wire bonder 100. The transducer 134 applies ultrasonic vibrations to the vicinity of the tip of the wire 300 via the capillary 133 during bonding. The capillary 133 guides the wire 300 and supplies it to the pad electrode 321 and the lead electrode 322, and during bonding, its tip presses the wire 300 against the pad electrode 321 and the lead electrode 322. The wire 300 is supplied from a wire supply unit (not shown) that includes a tensioner and a rotating spool. The material of the wire 300 is appropriately selected depending on the type and properties of the semiconductor chip 320, and gold, silver, or copper is used, for example.

[0015] The torch 131 is supported by the head unit 110 and has a discharge electrode at its tip. During the first bond to the pad electrode 321, a certain length of wire 300 is unwound from the tip of the capillary 133 to form a wire tail. In this state, the tip of the wire tail faces the electrode of the torch 131 along the X-axis direction, and as shown in the figure, a molten free air ball (FAB) 301 is formed by applying a voltage to the electrode. The tool unit 120 can be moved in the height direction relative to the head unit 110 by the tool drive motor 142, and the tip of the wire tail can be made to face the electrode of the torch 131 or moved closer to or farther away from the pad electrode 321 or the lead electrode 322. As shown in the figure, the height direction is the Z-axis direction, which is perpendicular to the planar direction.

[0016] The first imaging unit 151 is an imaging unit for imaging the FAB301 formed at the tip of the wire tail from the Y-axis direction, and is supported by the head part 110. The first imaging unit 151 includes an imaging element that outputs an image signal and an optical system that forms an image of the FAB301 on the imaging element. The second imaging unit 152 is an imaging unit for imaging the FAB301 formed at the tip of the wire tail from the X-axis direction, and is supported by the head part 110, just like the first imaging unit 151. The second imaging unit 152 also includes an imaging element that outputs an image signal and an optical system that forms an image of the FAB301 on the imaging element. In the following description, the first imaging unit 151 and the second imaging unit 152 may be collectively referred to as the imaging unit.

[0017] The XYZ coordinate system is a spatial coordinate system with its origin at the reference position of the head unit 110. In the subsequent drawings, similar coordinate axes may also be written to indicate the orientation of each element.

[0018] 2 is a system configuration diagram of the wire bonder 100. The control system of the wire bonder 100 is mainly composed of an arithmetic processing unit 170, a storage unit 180, an input / output device 190, a torch 131, a clamper 132, a transducer 134, a head drive motor 141, a tool drive motor 142, a first imaging unit 151, and a second imaging unit 152. The arithmetic processing unit 170 is a processor (CPU: Central Processing Unit) that controls the wire bonder 100 and executes programs. The processor may be configured to work in conjunction with an arithmetic processing chip such as an ASIC (Application Specific Integrated Circuit) or a GPU (Graphics Processing Unit). The arithmetic processing unit 170 reads out a control program stored in the storage unit 180 and executes various processes related to bonding.

[0019] The storage unit 180 is a non-volatile storage medium and is configured, for example, by an HDD (Hard Disk Drive). The storage unit 180 can store various parameter values, functions, lookup tables, etc. used for control and calculation, in addition to programs for executing control and processing of the wire bonder 100. The input / output device 190 includes, for example, a keyboard, a mouse, and a display monitor, and is a device that accepts menu operations by an operator and presents information to the operator. For example, the calculation processing unit 170 may display the measurement results of the FAB together with captured images on a display monitor, which is one of the input / output devices 190.

[0020] When the torch 131 receives a discharge instruction signal from the arithmetic processing unit 170, it applies a voltage to the electrode. When a voltage is applied to the electrode, an arc discharge occurs between the electrode and the wire tail, and a fabricated adhesive (FAB) is formed at the tip of the wire tail. The clamper 132 closes its hand while it receives a grip instruction signal from the arithmetic processing unit 170. When the grip instruction signal is released, the hand opens. While the hand is closed, the wire 300 is not paid out from or retracted into the capillary 133. When the transducer 134 receives a vibration signal from the arithmetic processing unit 170, it vibrates the vibrator. The ultrasonic vibrations generated by the transducer 134 contribute to joining the wire 300.

[0021] The head drive monitor 141 receives a drive signal from the arithmetic processing unit 170 to move the head unit 110 in the planar direction. The tool drive motor 142 receives a drive signal from the arithmetic processing unit 170 to move the tool unit 120 in the height direction.

[0022] The first imaging unit 151 receives an imaging request signal from the arithmetic processing unit 170, performs imaging, and transmits the first image output by the imaging element as an image signal to the arithmetic processing unit 170. Similarly, the second imaging unit 152 receives an imaging request signal from the arithmetic processing unit 170, performs imaging, and transmits the second image output by the imaging element as an image signal to the arithmetic processing unit 170.

[0023] The arithmetic processing unit 170 also serves as a functional calculation unit that executes various calculations in response to processing instructed by the control program. The arithmetic processing unit 170 can function as a measurement unit 171, an adjustment unit 172, and a drive control unit 173. The measurement unit 171 transmits an imaging request signal to the first imaging unit 151 and the second imaging unit 152, acquires an image signal of the first image and an image signal of the second image, and measures the deviation of the FAB relative to the central axis of the wire 300. The adjustment unit 172 adjusts the discharge conditions of the torch 131 based on the measurement results by the measurement unit 171. The drive control unit 173 generates a drive signal for driving the head drive motor 141 and a drive signal for driving the tool drive motor 142, and transmits them to the respective motors.

[0024] 3 is a diagram illustrating the observation of the FAB. As described above, the wire 300 is unwound from the tip of the capillary 133 to form a wire tail, and the tip of the wire tail is subjected to arc discharge by the torch 131 from the positive direction of the X axis, forming the FAB 301.

[0025] Depending on the discharge conditions of the torch 131, the FAB 301 may be formed with a bias relative to the central axis of the wire 300. If the amount of bias exceeds the allowable limit, it can cause the compression ball formed on the pad electrode 321 to be eccentric during first bonding, resulting in defects such as short circuits between the pad electrodes 321. The bias of the FAB 301 is influenced by various factors, such as the composition and diameter of the wire 300, tail length, and ambient temperature. Therefore, it is preferable to form the FAB 301 under conditions under which the wire bonding operation is actually performed and evaluate whether the amount of bias exceeds the allowable limit. Even if the amount of bias exceeds the allowable limit, it may be possible to suppress it to within the allowable limit by adjusting the discharge conditions of the torch 131. Therefore, the wire bonder 100 in this embodiment captures an image of the actually formed FAB 301 and measures its bias.

[0026] The first imaging unit 151 is installed to image the wire tail including the FAB301 from the Y-axis direction, i.e., a direction perpendicular to the Z-axis direction, which is the payout direction of the wire tail from the capillary 133, and the X-axis direction, which is the discharge direction of the arc discharge. The first imaging unit 151 generates an image signal of a first image obtained by imaging the wire tail from the Y-axis direction. In this embodiment, the first imaging unit 151 is installed to image the wire tail from the negative Y-axis direction, but it may also be installed to image from the positive Y-axis direction. Since bias in the FAB301 is likely to occur in the discharge direction, the bias can be accurately determined from the first image captured from a direction perpendicular to the discharge direction.

[0027] The second imaging unit 152 is installed so as to image the wiretail including the FAB301 from the X-axis direction. The second imaging unit 152 generates an image signal of a second image obtained by imaging the wiretail from the X-axis direction. In this embodiment, the second imaging unit 152 is installed so as to image the wiretail from the negative X-axis direction, but it may also be installed so as to image the wiretail from the positive X-axis direction. If the second image is also used as the measurement target in addition to the first image, the bias of the FAB301 can be accurately grasped from two orthogonal directions.

[0028] The imaging section of this embodiment is composed of two imaging units, the first imaging unit 151 and the second imaging unit 152, but more imaging units may be added. In this case, it is desirable that the additional imaging unit be installed so that it can capture an image of the wire tail from a direction perpendicular to the Z axis, which is the payout direction of the wire tail.

[0029] The measurement unit 171 measures the bias of the FAB 301 from the acquired image. Here, the two measurement methods will be described with reference to the drawings.

[0030] 4 is a diagram illustrating a first method for measuring the bias of the FAB 301. The measuring unit 171 measures a first bulge amount, which is the amount of bulge of the FAB 301 in one direction relative to the central axis of the wire 300, and a second bulge amount, which is the amount of bulge in another direction opposite to the first direction.

[0031] The left diagram in FIG. 4 shows the first image acquired by the first imaging unit 151. In the first image, the first bulge amount is the distance D1 from the surface of the wire 300 (a boundary offset by the radius of the wire 300 toward the positive side of the X axis relative to the central axis of the wire 300) to the vertex of the FAB 301 on the positive side of the X axis. Similarly, the second bulge amount is the distance D2 from the surface of the wire 300 (a boundary offset by the radius of the wire 300 toward the negative side of the X axis relative to the central axis of the wire 300) to the vertex of the FAB 301 on the negative side of the X axis. For example, if the eccentricity evaluation value is 1.0-Min(D1,D2) / Max(D1,D2), and a "-" sign is assigned when Max(D1,D2)=D1, and a "+" sign is assigned when Max(D1,D2)=D2, the degree of deviation can be expressed to which side. If D1=D2, the eccentricity evaluation value is 0, indicating that there is no deviation in the imaging direction of the first image.

[0032] The right diagram in FIG. 4 shows the second image acquired by the second imaging unit 152. In the second image, the first bulge amount is the distance D3 from the surface of the wire 300 (the boundary line offset by the radius of the wire 300 toward the negative Y-axis from the central axis of the wire 300) to the vertex of the FAB 301 on the negative Y-axis side. Similarly, the second bulge amount is the distance D4 from the surface of the wire 300 (the boundary line offset by the radius of the wire 300 toward the positive Y-axis from the central axis of the wire 300) to the vertex of the FAB 301 on the positive Y-axis side. Similarly, the eccentricity evaluation value is set to 1.0-Min(D3,D4) / Max(D3,D4), and a "-" sign is assigned when Max(D3,D4)=D3, and a "+" sign is assigned when Max(D3,D4)=D4, thereby indicating the degree of deviation to either side. If D3=D4, the eccentricity evaluation value is 0, indicating that there is no deviation in the imaging direction of the second image.

[0033] Since the diameter of the actual wire 300 inserted in the capillary 133 is known, the actual distance per pixel can be calculated from the width of the wire 300 on the image. This allows conversion from the distance on the image (number of pixels) to the actual distance.

[0034] 5 is a diagram illustrating a second method for measuring the deviation of the FAB 301. The measurement unit 171 measures the deviation amount of the center of the FAB 301 relative to the central axis of the wire 300.

[0035] 5 shows the first image acquired from the first imaging unit 151. In the first image, the amount of deviation is the distance from the central axis of the FAB 301 to the center C of the FAB 310. X Distance D to X For example, the eccentricity evaluation value = D X And C X When the axis is on the positive side of the X axis, the sign is "-", and when the axis is on the positive side of the X axis, the sign is "-". X If D is on the negative side of the X axis, it can be expressed by adding a "+" sign to indicate how much it is biased to one side. X If .DELTA..times ...

[0036] 5 shows a second image acquired from the second imaging unit 152. In the second image, the amount of deviation is the distance from the central axis of the FAB 301 to the center C of the FAB 310. Y Distance D to Y For example, the eccentricity evaluation value = D Y And C Y When the axis is on the negative side of the Y axis, the sign is "-", and when the axis is on the negative side of the Y axis, the sign is "-". Y If D is on the positive side of the Y axis, it can be expressed by adding a "+" sign to indicate how much it is biased to one side. Y If ≠ 0, the eccentricity evaluation value is 0, and it can be seen that there is no bias in the imaging direction of the second image. The conversion from the distance on the image (number of pixels) to the actual distance is the same as in the case of Figure 4.

[0037] The eccentricity measurement of the FAB 310 by the measuring unit 171 can be incorporated in various ways into the manufacturing process in which the actual wire connection work is carried out. Here, three embodiments will be described with reference to the drawings.

[0038] 6 is a flow diagram illustrating the processing procedure of a first example including FAB eccentricity measurement according to this embodiment. In the first example, prior to performing a wire connection operation, FAB eccentricity measurement is performed to determine the discharge conditions of the torch 131 so that a FAB that meets the criteria is formed. The illustrated flow is started, for example, at the preparation stage before performing the wire connection operation.

[0039] In step S111, the adjustment unit 172 receives input of initial settings related to the discharge conditions of the torch 131 via the input / output device 190. The adjustment unit 172 may use predetermined initial settings, not limited to input via the input / output device 190. In step S112, the drive control unit 173 draws in the wire 300 from the wire supply unit and pays out the wire 300 from the tip of the capillary 133 to form a wire tail. At this time, if the tip of the formed wire tail does not face the electrode of the torch 131, the tool drive motor 142 is driven to adjust the height of the wire tail so that it faces the electrode.

[0040] In step S113, the adjustment unit 172 applies a voltage to the electrode of the torch 131 according to the set discharge conditions to form the FAB 301 at the tip of the wire tail. In step S114, the measurement unit 171 transmits an imaging request signal to each of the first imaging unit 151 and the second imaging unit 152 to cause them to perform imaging processing, thereby acquiring first and second images of the wire tail including the FAB 301. Then, in step S115, the measurement unit 171 measures the deviation of the FAB 301 from the central axis of the wire 300 from the first and second images using one of the measurement methods described with reference to FIGS. 4 and 5. The measurement method to be used may be selectable in advance by an operator, or may be automatically selected according to settings of the semiconductor chip 320, etc. Alternatively, the control program may support only one of the measurement methods.

[0041] In step S116, the measurement unit 171 determines whether the measurement result satisfies a preset standard. The standard is, for example, set as the allowable amount of the eccentricity evaluation value that does not pose a risk of causing inconvenience such as a short circuit between the pad electrodes 321. If the eccentricity evaluation value, which is the measurement result, exceeds the allowable amount, the process proceeds to step S117. If it is within the allowable amount, it is determined that an appropriate FAB can be formed under the set and adjusted discharge conditions, and the series of preparations is terminated, waiting until the wiring work for the semiconductor chip 320 is performed.

[0042] If the process proceeds to step S117, the calculation processing unit 170 attaches the formed FAB 301 to a dummy electrode pad or the like, closes the clamper 132, and cuts the wire 300. Then, in step S118, the adjustment unit 172 adjusts the discharge conditions in consideration of the measurement results by the measurement unit 171. That is, if the eccentricity is in a fixed direction, the adjustment unit 172 changes the spark current, current ramp time, gas flow rate, etc., taking into account differences in the cooling rate of the FAB surface. If the eccentricity direction changes randomly, the adjustment unit 172 changes the parameters of the discharge conditions according to the magnitude and direction of the deviation, such as adding a pre-spark delay time, taking into account the influence of vibration. Once the adjustment of the discharge conditions is complete, the process returns to step S112 to evaluate the FAB 301 formed under the adjusted discharge conditions, and the series of processes continues.

[0043] By moving on to the wiring work of the semiconductor chip 320 after such preparatory work, it is possible to realize the formation of a stable FAB from the initial stage of the wiring work.

[0044] 7 is a flow diagram illustrating the processing procedure of a second example including measurement of eccentricity of a fabrication machine according to this embodiment. In the second example, the fabrication machine that is actually formed is monitored during execution of a wire connection operation. The illustrated flow begins when wire connection is started for each semiconductor chip 320 on a substrate 330 placed on a stage 220. Note that the same steps as those described using FIG. 6 are given the same step numbers, and their description will be omitted unless otherwise noted.

[0045] When the flow starts, steps S111 to S116 are executed in the same manner as the corresponding steps in Fig. 6. However, the FAB 301 formed here is not formed on a trial basis for measurement purposes, but is actually attached to the pad electrode 321 of the semiconductor chip 320.

[0046] If the measurement unit 171 determines in step S116 that the criteria are met, the process proceeds to step S121. The drive control unit 173 attaches the formed FAB 301 to the target pad electrode 321 to perform first bonding. At this time, the calculation processing unit 170 performs control associated with the first bonding, such as transmitting an excitation signal to the transducer 134.

[0047] Next, in step S122, the drive control unit 173 moves the wire 300 to the corresponding lead electrode 322 to perform second bonding. At this time, the arithmetic processing unit 170 executes control associated with the second bonding, such as sending an excitation signal to the transducer 134. The arithmetic processing unit 170 proceeds to step S123, closes the clamper 132 to cut the wire 300, and proceeds to step S124.

[0048] In step S124, the arithmetic processing unit 170 checks whether all bonding processes have been completed. If not, the process returns to step S112 to execute the remaining bonding processes and continues the series of processes. If all bonding processes have been completed, the series of bonding processes ends.

[0049] If the measurement unit 171 determines in step S116 that the criteria are not met, the process proceeds to step S125, where the drive control unit 173 retreats the formed FAB 301 to a predetermined position without contacting it with the target pad electrode 321. Then, the calculation processing unit 170 executes a warning process, such as issuing a warning sound, to notify the operator that the process has been interrupted, and then interrupts and terminates the series of processes.

[0050] By adopting such a processing procedure, problems such as short circuits between the pad electrodes 321 can be prevented in advance.

[0051] FIG. 8 is a flow diagram illustrating the processing procedure of a third embodiment, including FAB eccentricity measurement according to this embodiment. In the third embodiment, the FAB actually formed is monitored during the execution of the wire connection work, and if the measurement results satisfy certain conditions, the discharge conditions are adjusted while the wire connection work continues. The illustrated flow, like the flow in FIG. 7, begins when the wire connection work is started for each semiconductor chip 320 on the substrate 330 placed on the stage 220. Note that the same steps as those described using FIGS. 6 and 7 are assigned the same step numbers, and their description will be omitted unless otherwise noted.

[0052] When the flow starts, steps S111 to S115 are the same as the corresponding steps in FIG. 7. When the flow proceeds from step S115 to step S131, the measurement unit 171 determines whether the measurement results satisfy a preset first criterion. The first criterion is a criterion that, if not satisfied, is determined to be highly likely to cause a problem such as a short circuit between the pad electrodes 321, and the range is determined, for example, by an eccentricity evaluation value. If the measurement results satisfy the first criterion, the flow proceeds to step S121, where first bonding is started. If the measurement results do not satisfy the first criterion, the flow proceeds to step S125, where evacuation and warning processing are executed, and the series of processes are interrupted and terminated.

[0053] If the process proceeds to step S121, the process continues as described above until step S123. Then, if the process proceeds to step S132, the measurement unit 171 determines whether the measurement result measured in step S115 satisfies a second criterion. The second criterion is a criterion that, if met, can be evaluated as an optimal shape, and a range with less deviation than the first criterion is set. If the second criterion is not met but the first criterion is met, continuing the wiring work as is will not cause any problems such as short circuits between the pad electrodes 321. However, there is a possibility that the first criterion will no longer be met due to some trigger. Therefore, if the measurement unit 171 determines that the second criterion is not met in step S132, the process proceeds to step S133, where the adjustment unit 172 adjusts the discharge conditions taking the measurement result into consideration. That is, the parameters of the discharge conditions are changed depending on the magnitude and direction of the deviation. Then, the process proceeds to step S124. If the measurement unit 171 determines that the second criterion is met in step S132, the process skips step S133 and proceeds to step S124.

[0054] By adopting such a processing procedure, it is possible to prevent problems such as short circuits between the pad electrodes 321 and continuously adjust the discharge conditions, thereby enabling more optimal wiring work. When observing the FAB 301 formed continuously in this manner, changes in the bias can also be grasped. The adjustment unit 172 may adjust the discharge conditions taking such changes into account. Furthermore, if a trained model is prepared that is generated from training data of the bias of the FAB 301 formed thereafter based on the measured eccentricity evaluation value and the adjusted discharge conditions, the adjustment unit 172 can also adjust the discharge conditions using such a trained model. In this case, data obtained through the actual wiring work may be used as training data for re-learning.

[0055] In the wire bonder 100 described above, the imaging section is configured with two imaging units, the first imaging unit 151 and the second imaging unit 152, but from the perspective of simplifying the device, the imaging section may be configured with a single imaging unit. Fig. 9 is a perspective view schematically showing the main parts of a wire bonder 100' according to another embodiment. Components similar to those of the wire bonder 100 are given the same reference numerals and descriptions thereof will be omitted.

[0056] The wire bonder 100' differs from the wire bonder 100 in that the imaging section is composed of a single imaging unit 151', which is installed on the stand 210. When the imaging section is composed of a single imaging unit, as described above, it is preferable to install it so that it images the wire tail including the FAB 301 from a direction perpendicular to the discharge direction. The wire bonder 100' is equipped with the imaging unit 151' so that it images the wire tail from the positive direction of the Y axis, but it may also be equipped so that it images the wire tail from the negative direction of the Y axis.

[0057] Furthermore, if the imaging unit 151' is installed so as to be supported by the pedestal 210, it will not move in accordance with the operation of the head unit, and the wire tail can be observed stably. However, in this case, the space available for imaging the wire tail is limited, and therefore the drive control unit 173 must drive the head unit 110 and the tool unit 120 so that the wire tail is positioned in that space. From this perspective, a configuration in which the imaging unit is supported by the pedestal 210 is preferable when implementing the first embodiment described above. Note that multiple imaging units may be installed on the pedestal 210 so that the wire tail can be observed from two or more directions.

[0058] Although the wire bonder 100 has been described above as an example of a wire bonding apparatus, bonding apparatuses to which the method and configuration for measuring FAB bias according to this embodiment can be applied are not limited to the example of the wire bonder 100 that connects two bonding points with a wire. For example, the present invention can also be applied to a bump bonder that forms bumps on each of a plurality of electrodes on a substrate. [Explanation of symbols]

[0059] 100, 100'...wire bonder, 110...head section, 120...tool section, 130...first imaging unit, 131...torch, 132...clamper, 133...capillary, 134...transducer, 141...head drive motor, 142...tool drive motor, 151...first imaging unit, 151'...imaging unit, 152...second imaging unit, 170...arithmetic processing section, 171...measurement section, 172...adjustment section, 173...drive control section, 180...storage section, 190...input / output device, 210...frame, 220...stage, 300...wire, 301...FAB (free air ball), 320...semiconductor chip, 321...pad electrode, 322...lead electrode, 330...substrate

Claims

1. a capillary for supplying a bonding wire; a torch for forming a free air ball on the wire tail of the bonding wire paid out from the capillary; an imaging unit that images the wire tail in a state in which the free air ball is formed at a tip portion of the wire tail by the torch; a measuring unit that measures a deviation of the free air ball with respect to a central axis of the bonding wire based on the image output from the imaging unit; an adjustment unit that adjusts discharge conditions of the torch so that the free air ball that satisfies a preset criterion is formed when it is determined that the measurement result by the measurement unit does not satisfy the preset criterion; A wire bonding apparatus comprising:

2. 2. The wire bonding apparatus according to claim 1, wherein the adjustment unit adjusts discharge conditions of the torch prior to execution of a bonding operation.

3. 2. The wire bonding apparatus according to claim 1, wherein the adjustment section terminates the bonding operation when it is determined that another criterion set in a range in which the deviation is greater than the criterion is not satisfied during the bonding operation.

4. The wire bonding apparatus according to any one of claims 1 to 3, wherein the adjustment unit adjusts the discharge conditions by changing at least one of the spark current, current ramp time, gas flow rate, and pre-spark delay time based on the measurement results by the measurement unit.

5. The wire bonding apparatus according to any one of claims 1 to 4, wherein the measuring unit measures a first bulge amount, which is the amount of bulging of the free air ball in one direction relative to the central axis of the bonding wire, and a second bulge amount, which is the amount of bulging of the free air ball in another direction opposite to the first direction.

6. 6. The wire bonding apparatus according to claim 1, wherein the measurement unit measures an amount of deviation of a center of the free air ball from a central axis of the bonding wire.

7. The wire bonding apparatus according to any one of claims 1 to 6, wherein the imaging unit is installed to image the wire tail from a direction perpendicular to the direction in which the wire tail is unwound from the capillary and the discharge direction of the arc discharge generated between the torch and the wire tail.

8. 8. The wire bonding apparatus according to claim 1, wherein the imaging section includes a plurality of imaging units configured to image the wire tail from a plurality of directions perpendicular to a payout direction of the wire tail from the capillary.

9. a tail forming step of paying out the bonding wire from the tip of the capillary to form a wire tail; a free air ball forming step of forming a free air ball at the tip of the wire tail using a torch; an imaging step of imaging the wire tail in which the free air ball is formed; a measuring step of measuring a deviation of the free air ball with respect to a central axis of the bonding wire based on the image outputted in the imaging step; an adjusting step of adjusting discharge conditions of the torch so that the free air ball satisfying the criterion is formed when it is determined that the measurement result by the measuring step does not satisfy a preset criterion; A method for controlling a wire bonding apparatus comprising the steps of:

10. a tail forming step of paying out the bonding wire from the tip of the capillary to form a wire tail; a free air ball forming step of forming a free air ball at the tip of the wire tail using a torch; an imaging step of imaging the wire tail in which the free air ball is formed; a measuring step of measuring a deviation of the free air ball with respect to a central axis of the bonding wire based on the image outputted in the imaging step; an adjusting step of adjusting discharge conditions of the torch so that the free air ball satisfying the criterion is formed when it is determined that the measurement result by the measuring step does not satisfy a preset criterion; A control program for a wire bonding apparatus that causes a computer to execute the above.

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