JP6664300B2 - Wire bonding quality determination device and wire bonding quality determination method - Google Patents

Description

  The present invention relates to a wire bonding good / bad determination device and a wire bonding good / bad determination method for determining the quality of wire bonding performed by a wire bonding apparatus.

  In a conventional wire bonding apparatus using ultrasonic waves, a bonding tool that chucks a wire presses the wire against a workpiece and applies ultrasonic waves. As a result, the oxide film covering the contact surfaces of both the wire and the work is removed, a new surface is exposed, the exposed surfaces are in contact with each other, and the wire and the work are solid-bonded.

  In determining the quality of the bonding quality of the conventional wire bonding, a sample after the wire bonding is subjected to a current test or a destructive test such as a tensile test (also called a pull test) and a shear test (also called a shear test). Is common.

  However, in the method of performing the conduction test, the conduction test may not be possible depending on the configuration of the internal circuit of the IC. In addition, since destructive tests such as a tensile test and a shear test are extraction tests, it is difficult to perform a process such as stopping a wire bonding apparatus when a bonding defect actually occurs. Furthermore, it is necessary to carry out a separate evaluation in order to investigate the cause of the occurrence of the bonding failure, and the evaluation requires a lot of time and labor.

  Therefore, in the related art described in Patent Document 1, a vibration frequency of a tool during bonding is observed by a laser Doppler vibrometer, an amount of increase in frequency after a lapse of a predetermined time from the start of bonding is calculated, and the calculated frequency is calculated. By comparing the amount of increase with the threshold value set in advance, the quality of the joining quality is determined.

  Further, in the conventional technique described in Patent Document 2, the frequency of a transducer driving voltage for vibration of a bonding tool is observed, and an increase in frequency after a lapse of a predetermined time is compared with a preset threshold value to perform bonding. Judge the quality.

  As described above, in each of the prior arts described in Patent Documents 1 and 2, attention is paid to a frequency near the bonding fundamental frequency, and non-destructive without being affected by other low-frequency vibrations, noise, and the like. In addition, it is possible to judge the quality of the joining quality with high accuracy in real time.

JP 2013-125875 A JP 2014-232791 A

However, the prior art has the following problems.
In the prior art described in Patent Document 1, it is difficult to fix the vibrometer on the wire bonding apparatus due to the size and mass restrictions of the laser Doppler vibrometer, and there are a plurality of different bonding points in one work. There is a problem that it cannot cope with a bonding apparatus in continuous operation. In the related art described in Patent Document 2, since the vibration state change at the tip of the tool is performed at the base of the vibrator called a horn, there is a problem that it is difficult to catch the change in the vibration state due to the change in the joining state.

  The present invention has been made in order to solve the above-described problems, and performs real-time determination of bonding quality in response to continuous operation of bonding, and has higher reliability of determination than conventional wires. It is an object of the present invention to obtain a bonding quality determination device and a wire bonding quality determination method.

The wire bonding pass / fail determination device according to the present invention is embedded in a stage on which a work is placed, and when the wire bonding for ultrasonically bonding the bonding wire to the work is performed by the bonding tool, a three-axis direction applied from the bonding tool to the work is provided. A three-axis force detection element for detecting the load of the three-axis force detection device, and a control device for determining whether the bonding quality of the wire bonding is good or bad from at least one of the loads in the three-axis direction detected by the three-axis force detection element. The direction parallel to the surface of the workpiece and orthogonal to the ultrasonic vibration direction of the ultrasonic wave transmitted from the bonding tool is defined as the X-axis direction, the ultrasonic vibration direction is defined as the Y-axis direction, the X-axis direction and the Y-axis direction. When the wire bonding is performed, the bonding tool presses the bonding wire to the workpiece. When the attaching direction is the Z-axis direction, the loads in the three-axis directions are an X-direction load that is a load in the X-axis direction, a Y-direction load that is a load in the Y-axis direction, and a Z direction that is a load in the Z-axis direction. The control device determines the frequency component of the Y-direction load by performing frequency analysis on the time-axis waveform of the Y-direction load detected by the three-axis force detection element. The quality of the joining quality is determined based on the frequency component of the Y-direction load .

The wire bonding quality determination method according to the present invention is characterized in that, when wire bonding for ultrasonically bonding a bonding wire to a work is performed by the bonding tool, a triaxial load applied to the work from the bonding tool by using the triaxial force detecting element. And a step of judging the quality of the bonding quality of the wire bonding from at least one of the loads obtained in the three axial directions. The step is executed by the control device, and the step of And the direction perpendicular to the ultrasonic vibration direction of the ultrasonic wave transmitted from the bonding tool is defined as the X-axis direction, the ultrasonic vibration direction is defined as the Y-axis direction, and the direction orthogonal to the X-axis direction and the Y-axis direction. The bonding tool presses the bonding wire against the workpiece when bonding is performed When the direction is the Z-axis direction, the loads in the three-axis directions are an X-direction load which is a load in the X-axis direction, a Y-direction load which is a load in the Y-axis direction, and a Z-direction load which is a load in the Z-axis direction. In the determining step, the frequency component of the Y-direction load is obtained by performing frequency analysis on the time-axis waveform of the Y-direction load detected by the three-axis force detection element, and the frequency component of the Y-direction load is obtained. The quality of the joining quality is determined based on the frequency component of the Y-direction load .

  ADVANTAGE OF THE INVENTION According to this invention, while performing the quality judgment of joining quality in real time corresponding to continuous operation | movement of bonding, it is possible to obtain a wire bonding quality determination device and a wire bonding quality determination method with higher reliability of the determination than before. it can.

FIG. 1 is a configuration diagram illustrating a wire bonding pass / fail determination device according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a control system of the vibrator in FIG. 1. FIG. 2 is a schematic view of the bonding tool viewed from the front when wire bonding is performed by the bonding tool of FIG. 1. FIG. 2 is a diagram illustrating a time transition of a voltage output from a voltage detection unit in FIG. 1. FIG. 5 is an enlarged view of a part a in FIG. 4. FIG. 5 is a diagram illustrating a time axis waveform of a Y-direction load in FIG. 4. FIG. 7 is a diagram illustrating frequency components obtained by performing FFT analysis on the waveform of a part b in FIG. 6. FIG. 7 is a diagram showing both a frequency component obtained by performing FFT analysis on the waveform of part b in FIG. 6 and a frequency component obtained by performing FET analysis on the waveform of f in FIG. 6. FIG. 2 is a diagram illustrating a time transition of each of a Y-direction load at a basic vibration frequency and a Y-direction load at a high vibration frequency when wire bonding is performed by the bonding tool 2 of FIG. 1. FIG. 4 is a diagram illustrating a time transition of a ratio of a Y-direction load at a high vibration frequency to a sum of a Y-direction load at a basic vibration frequency and a Y-direction load at a high vibration frequency in the first embodiment of the present invention. It is a figure which shows the time transition of the shear intensity | strength in Embodiment 2 of this invention, and the time transition of a crushing width. FIG. 12 is an external view of a wire after wire bonding in a g part of FIG. 11. FIG. 7 is a diagram illustrating a frequency component obtained when FET analysis is performed on a time-axis waveform of a Y-direction load in a case where a bonding failure occurs in a third embodiment of the present invention in a section b of FIG. 6. FIG. 13 is a diagram illustrating frequency components obtained when FET analysis is performed on a time-axis waveform of an X-direction load when a joint failure occurs in the fourth embodiment of the present invention in a section h of FIG. 4. FIG. 15 is a diagram illustrating a time-axis waveform of a Z-direction load when no joint failure occurs according to the fifth embodiment of the present invention. FIG. 17 is a diagram showing a time-axis waveform of a Z-direction load when a bonding failure occurs in Embodiment 5 of the present invention.

  A wire bonding pass / fail determination device and a wire bonding pass / fail determination method according to an embodiment of the present invention will be described below with reference to the drawings. In the drawings, the same or similar components are denoted by the same reference numerals. In addition, in order to avoid the following description from being unnecessarily redundant and to facilitate understanding of parties, a detailed description of well-known matters and a redundant description of substantially the same configuration may be omitted. . Also, the following description and the contents of the accompanying drawings are not intended to limit the claimed subject matter.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing a wire bonding pass / fail determination device 102 according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a control system of the vibrator 1 of FIG. FIG. 3 is a schematic diagram when the bonding tool 2 is viewed from the front when wire bonding is performed by the bonding tool 2 of FIG.

  In FIG. 1, a wire bonding apparatus 101 includes a vibrator 1 and a bonding tool 2 (hereinafter, abbreviated as tool 2). The wire bonding apparatus 101 is an object whose quality of bonding is determined by the wire bonding quality determination apparatus 102. The wire bonding apparatus 101 is used, for example, in an assembly process of a semiconductor device or the like.

  The vibrator 1 generates ultrasonic vibration necessary for ultrasonic bonding. The tool 2 converts the longitudinal vibration of the vibrator 1 into bending vibration, and transmits the vibration to a bonding wire 5 (hereinafter, abbreviated as wire 5) as a bonding material, thereby joining the workpieces mounted on the stage 4. Wire bonding for ultrasonically bonding the wire 5 to the workpiece 3 as a material is performed. In addition, examples of the wire 5 include an aluminum wire, a gold wire, and a copper wire.

  In the wire bonding, the tool 2 applies ultrasonic vibration while the wire 5 is pressed against the work 3. As a result, the oxide film covering the contact surfaces of both the work 3 and the wire 5 is removed, and a new surface is exposed in both. Further, the two exposed surfaces come into contact with each other, and the wire 5 and the work 3 are solid-bonded.

  The wire bonding pass / fail determination device 102 includes a three-axis force detection element 6 embedded in a stage 4 on which the work 3 is placed, and a control device 103.

  When the wire bonding is performed by the tool 2, the triaxial force detecting element 6 detects a load in the three axial directions applied from the tool 2 to the work 3, and outputs the detection result to the control device 103.

  Here, the three-axis directions are parallel to the surface of the workpiece 3 and orthogonal to the ultrasonic vibration direction of the ultrasonic wave transmitted from the tool 2 (hereinafter, referred to as the X-axis direction), and the ultrasonic vibration direction. (Hereinafter referred to as the Y-axis direction), the direction orthogonal to the X-axis direction and the Y-axis direction, and the direction in which the tool 2 presses the wire 5 against the workpiece 3 when bonding is performed (hereinafter referred to as the Z-axis direction). Consists of FIG. 3 illustrates an X-axis direction 15, a Y-axis direction 16, and a Z-axis direction 17 as such three-axis directions.

  Therefore, the loads in the three-axis direction detected by the three-axis force detecting element 6 are a load in the X-axis direction (hereinafter, referred to as an X-direction load) and a load in the Y-axis direction (hereinafter, referred to as a Y-direction load). , And a load in the Z-axis direction (hereinafter, referred to as a Z-direction load).

  As described above, the load transmitted to the work 3 via the wire 5 during bonding is measured in the three-axis directions by the triaxial force detecting element 6 embedded in the stage 4 below the work 3.

  As the triaxial force detecting element 6, for example, a piezoelectric triaxial load sensor can be used. Since the piezoelectric type three-axis load sensor has high rigidity and high sensitivity and has a high-speed response, it can detect ultrasonic vibration applied below the work 3 via the wire 5 with high accuracy. Further, a plurality of triaxial force detecting elements 6 can be arranged in accordance with the size of the work 3 and the stage 4 and the bonding area.

  The control device 103 detects the charge output from the triaxial force detection element 6 into a voltage, a charge amplifier 7, a voltage detector 8 that detects the voltage converted by the charge amplifier 7, and a voltage detector 8 that detects the voltage. An analysis unit 9 that analyzes the applied voltage, and a determination unit 10 that determines whether the bonding quality of wire bonding is good or not based on the analysis result by the analysis unit 9.

  The analysis unit 9 and the determination unit 10 are realized by, for example, a CPU that executes a program stored in a memory and a processing circuit such as a system LSI.

  Next, a control system of the vibrator 1 will be described with reference to FIG. Here, in the wire bonding, the resonance frequency of the vibration system from the vibrator 1 to the tip of the tool 2 changes by changing the load state of the tool 2 during bonding. In order to prevent the ultrasonic vibration generated by the vibrator 1 from being attenuated and to efficiently transmit the ultrasonic energy from the tool 2 to the wire 5, a PLL (Phase Locked Loop) control is used as a control method of the vibrator 1. .

  In FIG. 2, a voltage applying device 11 applies a driving voltage to the vibrator 1. The voltage detection device 12 detects a drive voltage applied to the vibrator 1 from the voltage application device 11. The current detection device 13 detects a current output from the vibrator 1.

  The phase comparison device 14 compares the phase of the drive voltage detected by the voltage detection device 12 with the phase of the current detected by the current detection device 13, and adjusts the phase of the vibrator 1 so that the phase difference is constant. The oscillation frequency tracks the resonance frequency of the tool 2.

  Here, when a joint is formed between the wire 5 and the work 3, the wire 5 and the work 3 have an integrated structure, so that the resonance frequency of the vibration system increases and the oscillation frequency of the ultrasonic wave also increases. On the other hand, when the bonding between the wire 5 and the work 3 is insufficient, slippage occurs between the work 3 and the wire 5 and the resonance frequency of the vibration system does not increase, so that the ultrasonic oscillation frequency increases. Absent.

  In the first embodiment, the quality of the wire bonding is determined using the correlation between the increase in the resonance frequency during the wire bonding and the transition of the bonding strength.

  The experimental data shown in the following figures was obtained by actually performing experiments using the following ready-made products. That is, an ultrasonic wire bonding apparatus (3600 plus) manufactured by Orthodyne is used as the wire bonding apparatus 101, a frame made of a copper plate is used as the work 3, and an aluminum wire (TANW SOFT) manufactured by Tanaka Electronics Industry is used as the wire 5. -2 wire diameter 150 μm), a piezoelectric element (9017C) manufactured by Kistler was used as the triaxial force detecting element 6, and a charge amplifier (5015A) manufactured by Kistler was used as the charge amplifier 7.

  FIG. 4 is a diagram showing a time transition of the voltage output from the voltage detection unit 8 in FIG. The voltage detector 8 outputs the loads in the three axial directions detected by the three-axis force detecting element 6, that is, the X-direction load, the Y-direction load, and the Z-direction load in the form of a voltage.

  As can be seen from FIG. 4, after a Z-direction load 18 is applied to the work 3 via the wire 5, a Y-direction load 19 caused by ultrasonic vibration transmitted to the work 3 via the wire 5 in the Y-axis direction. Is started. On the other hand, the X-direction load 20 is not applied to the work 3.

  FIG. 5 is an enlarged view of a part a of FIG. As shown in FIG. 5, in the time axis waveform of the Y-direction load (hereinafter referred to as Y-direction waveform 21), the amplitude represents the magnitude of the Y-direction load, and the vibration frequency represents the frequency of the ultrasonic vibration. I have.

  The analysis unit 9 obtains the frequency component of the Y-direction load by performing frequency analysis on the Y-direction waveform 21 output from the voltage detection unit 8. Specifically, the analysis unit 9 divides the Y-direction waveform 21 into a plurality of time sections, and then converts the Y-direction waveform 21 into frequency components by fast Fourier transform (hereinafter, referred to as FFT).

  The FFT analysis is performed on a time section set by an arbitrary time length and the number of divisions, and the analysis unit 9 can also select and analyze an arbitrary time section from the divided time sections. .

  Here, the FFT analysis by the analysis unit 9 will be described with reference to FIGS. FIG. 6 is a diagram showing a time-axis waveform of the Y-direction load in FIG. FIG. 7 is a diagram showing frequency components obtained by performing FFT analysis on the waveform of the part b in FIG.

  The analysis unit 9 time-divides the waveform shown in FIG. 6 into five sections from part b to part f as an example, and then performs FET analysis on the waveform of each part to obtain a frequency component of the waveform of each part. Ask for.

  For example, by performing the FET analysis on the waveform of the part b corresponding to the time section at the initial stage of the joining, the frequency component of the waveform of the part b as shown in FIG. A frequency component is obtained.

  As shown in FIG. 7, in the frequency component of the Y-direction load corresponding to the initial stage of the joining, the value of the peak frequency 22 is 60.79 kHz, which is the initial oscillation frequency of the wire bonding apparatus 101. Hereinafter, the peak frequency 22 in the frequency component of the Y-direction load corresponding to the initial stage of joining is referred to as a fundamental vibration frequency. The fundamental vibration frequency is equal to the frequency of the ultrasonic vibration when the tool 2 is not pressed against the work 3 and the ultrasonic oscillation is performed in a no-load state.

  FIG. 8 is a diagram showing both the frequency component obtained by performing the FFT analysis on the waveform of the part b in FIG. 6 and the frequency component obtained by performing the FET analysis on the waveform for f in FIG. 6. By performing the FET analysis on the waveform of the portion f corresponding to the time section of the later stage of the joining, the frequency component of the waveform of the portion f, that is, the frequency component of the Y-direction load corresponding to the later stage of the joining, as shown in FIG. Is obtained.

  As shown in FIG. 8, when the work 3 and the wire 5 are joined, the load state on the tool 2 changes, and in the later stage of the joining, the vibration frequency peak shifts to a high frequency range of 61.03 kHz. That is, in the frequency component of the Y-direction load corresponding to the later stage of the joining, the value of the peak frequency 23 is 61.03 kHz.

  In addition, the term “late stage of bonding” as used herein means a time section in which the increase in shear strength is not observed in the time transition of the bonding strength previously examined by a shear test or the like. Hereinafter, the peak frequency 23 in the frequency component of the Y-direction load corresponding to the later stage of joining is referred to as a high vibration frequency.

  FIG. 9 is a diagram showing a time transition of each of the Y-direction load 24 at the fundamental vibration frequency and the Y-direction load 25 at the high vibration frequency when wire bonding is performed by the bonding tool 2 of FIG. As shown in FIG. 9, in the initial stage of the joining, the Y-direction load 24 whose frequency is the fundamental vibration frequency is dominant. When the time elapses from the initial stage of joining and the latter stage of joining, the Y-direction load 25 having a high vibration frequency becomes dominant.

  The analysis unit 9 obtains a Y-direction frequency component by performing frequency analysis on the time-axis waveform of the Y-direction load detected by the three-axis force detection element 6. The determination unit 10 determines a determination value as shown in FIG. 10 from the frequency component of the Y-direction load obtained by the analysis unit 9.

  FIG. 10 is a diagram showing a time transition of the ratio of the Y-direction load at the high vibration frequency to the sum of the Y-direction load at the fundamental vibration frequency and the Y-direction load at the high vibration frequency in the first embodiment of the present invention. Hereinafter, the ratio of the Y-direction load of the high vibration frequency to the sum of the Y-direction load of the basic vibration frequency and the Y-direction load of the high vibration frequency is referred to as a determination value.

  In FIG. 10, as a specific example of such a determination value, a determination value 26 obtained when wire bonding is normally performed is shown by a solid line, and a failure in which a joint is not formed between the wire 5 and the work 3 is shown. A determination value 27 obtained when the occurrence occurs is indicated by a broken line, and a determination value 28 obtained when a failure occurs in which the bonding between the wire 5 and the work 3 is insufficient and sufficient bonding strength is not obtained. Is indicated by a dashed line.

  As shown in FIG. 10, when there is a defect in which a joint is not formed between the wire 5 and the work 3, the determination value 27 does not increase with time. Further, when the bonding between the wire 5 and the work 3 is insufficient and a defect that the bonding strength is not sufficiently obtained occurs, the determination value 28 increases with time, but the determination value 26 increases. The degree of increase in the value from the initial stage to the later stage of the joining is smaller than that of the joining. As described above, the degree of increase in the determination value from the early stage of bonding to the late stage of bonding changes depending on whether or not a defect related to the bonding quality of wire bonding has occurred. In particular, the wire bonding can be performed without such a defect. The degree of increase of the determination value 26 when performed normally is the largest.

  Therefore, it is possible to determine in advance whether the bonding quality is good or bad by previously setting a determination value when the bonding quality is good as a determination threshold value and comparing the determination threshold value with the determination value.

  Therefore, in the first embodiment, the determination unit 10 determines whether the Y-direction load of the fundamental vibration frequency peaks in the frequency component of the Y-direction load corresponding to the initial stage of the joining, and the frequency component of the Y-direction load corresponding to the latter stage of the joining. By comparing a judgment value, which is a ratio of the Y-direction load of the high vibration frequency to the sum of the Y-direction load of the high vibration frequency that becomes the peak, and a predetermined judgment threshold value, it is possible to judge the quality of the joining quality. Is configured.

  The analysis unit 9 outputs the frequency component of the Y-direction load to the determination unit 10. The determination unit 10 determines a determination value from the frequency component of the Y-direction load output from the analysis unit 9 and compares the determination value with a determination threshold to determine whether the joining quality is good.

  In addition, various methods can be considered as a specific method of determining the quality of the joining quality by comparing the determination value with the determination threshold. For example, the following method may be adopted.

  That is, the relationship between the degree of increase in the determination value and the bonding strength is investigated in advance by various reliability tests such as a pull test and a shear test, and from the inspection results, the increase in the determination value when a desired bonding strength is obtained. The degree is set in the determination unit 10 as a determination threshold. The determining unit 10 compares the obtained increase in the determination value with the set determination threshold, and determines that the joining is good when the increase in the determination value is larger, and that the determination threshold is larger. Is determined to be a bonding failure.

  When the determination unit 10 determines that the connection is defective, the determination unit 10 outputs a device stop signal to the vibrator 1. The vibrator 1 stops driving when a device stop signal is input.

  As described above, according to the first embodiment, the frequency analysis is performed on the time-axis waveform of the Y-direction load detected by the three-axis force detection element embedded in the stage on which the work is placed, The frequency component of the Y-direction load is determined, and the Y-direction load of the basic vibration frequency that peaks in the frequency component of the Y-direction load corresponding to the early stage of the welding and the high vibration that peaks in the frequency component of the Y-direction load corresponding to the latter stage of the welding It is configured to judge the quality of the joining quality by comparing a judgment value which is a ratio of the Y-direction load of the high vibration frequency to the sum of the Y-direction load of the frequency and a predetermined judgment threshold value. .

  As described above, the vibration frequency of the excitation force by the ultrasonic wave is measured by the triaxial force detecting element embedded in the work lower stage, so that the vibration frequency can be measured regardless of the bonding point in the work. It is possible to judge the quality of the joining quality during continuous operation. In addition, by measuring the load transmitted directly to the work via the wire, it is possible to directly monitor the progress of the joining between the wire and the work, and as a result, it is possible to determine the quality of the joining quality with high accuracy. it can. That is, it is possible to judge the quality of the bonding quality in real time corresponding to the continuous operation of the bonding, and to increase the reliability of the judgment as compared with the related art.

Embodiment 2 FIG.
The second embodiment of the present invention utilizes the characteristic that the determination value in the first embodiment increases with the progress of the joining between the wire 5 and the work 3 and saturates to a constant value when the joining is completed. A description will be given of a case in which the quality of the joining quality is determined. In the second embodiment, the description of the same points as in the first embodiment will be omitted, and the points different from the first embodiment will be mainly described.

  FIG. 11 is a diagram showing a time transition 29 of the shear strength and a time transition 30 of the crushing width according to the second embodiment of the present invention. FIG. 12 is an external view of the wire 5 after wire bonding in a g part of FIG. In FIG. 11, the time transition 29 of the shear strength is shown by a solid line, and the time transition 30 of the collapse width is shown by a broken line.

  As shown in FIG. 11, the crushing width increases as the bonding time elapses, whereas the shear strength does not rise after a certain time has elapsed. In addition, as shown in FIG. 12, when the bonding time exceeds the appropriate time, a broken portion 31 is generated on the side surface of the wire 5, and as a result, the bonding quality is reduced.

  Therefore, the determination unit 10 determines the quality of the joining quality by comparing the elapsed time after the determination value described in the first embodiment exceeds the determination threshold value with a preset time threshold value. It is configured to be.

  Specifically, the relationship between the elapsed time after exceeding the judgment threshold value determined in the first embodiment and the joining quality is investigated in advance by various reliability tests such as a pull test, a shear test, and the like. Is set, which is a bonding time limit that does not cause a failure after exceeding the threshold value. The determination unit 10 compares the elapsed time after the obtained determination value exceeds the determination threshold value with the time threshold value, and determines that the bonding is defective if the elapsed time exceeds the time threshold value; Means that the bonding is good.

  When the determination unit 10 determines that the connection is defective, the determination unit 10 outputs a device stop signal to the vibrator 1. The vibrator 1 stops driving when a device stop signal is input.

  In addition, the type of bonding failure that can be determined by the configuration of the second embodiment is a bonding failure due to exceeding an appropriate bonding time, as described above. Therefore, in the second embodiment, when the determining unit 10 determines that the bonding is defective, the determining unit 10 can estimate that the cause of the bonding failure is due to exceeding the appropriate bonding time, and determines the cause of the bonding failure. Can be identified.

  As described above, according to the second embodiment, in comparison with the configuration of the first embodiment, the elapsed time after the determination value exceeds the determination threshold is compared with a preset time threshold. It is configured to determine the quality of the joining quality.

  Thereby, the same effect as that of the first embodiment can be obtained, and further, as a type of the bonding failure, a bonding failure due to exceeding an appropriate bonding time can be detected.

Embodiment 3 FIG.
In the third embodiment of the present invention, the quality of the joining quality is determined by monitoring frequency peaks other than an integral multiple of the fundamental vibration frequency in the frequency component of the Y-direction load obtained by the analysis unit 9. The case will be described. In the third embodiment, the description of the same points as in the first embodiment will be omitted, and the points different from the first embodiment will be mainly described.

  FIG. 13 is a diagram showing a frequency component obtained when the FET analysis is performed on the time axis waveform of the Y-direction load in the case where a bonding failure occurs in the third embodiment of the present invention in a section b of FIG. 6. is there.

  In FIG. 13, a peak 32 due to the fundamental vibration frequency, a peak 33 due to a frequency that is an integral multiple of the fundamental vibration frequency, and a peak 34 due to a frequency other than an integral multiple of the fundamental vibration frequency are seen. Further, when bonding is performed under a high load condition, the collapse of the wire 5 increases, and the tip of the tool 2 interferes with the work 3, so that a peak 34 as shown in FIG. 13 appears.

  Therefore, the determination unit 10 is configured to determine the quality of the joining quality based on whether or not the peak 34 having a frequency other than an integral multiple of the fundamental vibration frequency is detected in the frequency component of the Y-direction load.

  Specifically, when the peak 34 is detected in the frequency component of the Y-direction load, the determination unit 10 determines that the bonding is poor, and otherwise determines that the bonding is good. In addition, by investigating by various reliability tests, such as a pull test and a shear test, the peak strength which becomes a desired joining strength is set as a threshold value. Then, the threshold value is compared with the intensity of the peak 34. If the threshold value is higher, it is determined that the peak 34 has not been detected. If the intensity of the peak 34 is higher, the peak 34 is detected. It may be determined that it has been done.

  When the determination unit 10 determines that the connection is defective, the determination unit 10 outputs a device stop signal to the vibrator 1. The vibrator 1 stops driving when a device stop signal is input.

  Further, the type of bonding failure that can be determined by the configuration of the third embodiment is, as described above, a bonding failure due to a collapse abnormality caused by a high load condition. Therefore, in the third embodiment, when the determination unit 10 determines that the connection is defective, the determination unit 10 can estimate that the cause of the connection failure is due to the collapse abnormality caused by the high load condition. Can be identified.

  It should be noted that the method of judging the quality of the joint quality shown in the third embodiment can be performed on one or a plurality of time-divided arbitrary sections.

  As described above, according to the third embodiment, whether a frequency peak other than an integral multiple of the fundamental vibration frequency that is a peak in the frequency component of the Y-direction load corresponding to the initial stage of joining is detected in the frequency component of the Y-direction load? It is configured to judge whether the joining quality is good or not based on the judgment.

  Thus, the same effect as that of the first embodiment can be obtained, and further, as the type of the joining failure, the joining failure due to the crushing abnormality caused by the high load condition can be detected.

Embodiment 4 FIG.
In the fourth embodiment of the present invention, a case will be described in which the quality of the joining quality is determined using the frequency component of the X-direction load detected by the triaxial force detecting element 6. In the fourth embodiment, the description of the same points as in the first embodiment is omitted, and the points different from the first embodiment will be mainly described.

  The analysis unit 9 performs a frequency analysis on the time-axis waveform of the X-direction load detected by the three-axis force detection element 6 with respect to the configuration of the first embodiment, thereby obtaining the frequency of the X-direction load. Find more components. The FFT analysis is performed on a time section set by an arbitrary time length and the number of divisions, and the analysis unit 9 can also select and analyze an arbitrary time section from the divided time sections. .

  FIG. 14 is a diagram showing a frequency component obtained when the FET analysis is performed on the time axis waveform of the X-direction load when a joint failure occurs in the fourth embodiment of the present invention in a section h of FIG. 4. is there.

  Here, when the bonding quality is good, that is, when the wire bonding is performed normally, no load is detected in the X-axis direction, and the FFT analysis is performed on the time-axis waveform of the X-direction load. No clear frequency peak is seen. On the other hand, if the pressing of the work 3 during the wire bonding is insufficient, the work 3 vibrates in the X-axis direction, so that the ultrasonic vibration is not efficiently transmitted to the wire 5, and as a result, Failure occurs.

  As shown in FIG. 14, when a joint failure due to the vibration of the work 3 occurs, a peak 35 that is an integral multiple of the fundamental vibration frequency is seen in the frequency component of the X-direction load. The peak 35 is not seen when the bonding quality is good.

  Therefore, the determination unit 10 is configured to determine the quality of the bonding quality based on whether or not the peak 35 of a frequency that is an integral multiple of the fundamental vibration frequency is detected in the frequency component of the X-direction load.

  Specifically, when the peak 35 is detected in the frequency component of the load in the X direction, the determination unit 10 determines that the bonding is poor, and otherwise determines that the bonding is good. In addition, by investigating by various reliability tests, such as a pull test and a shear test, the peak strength which becomes a desired joining strength is set as a threshold value. Then, the threshold value is compared with the intensity of the peak 35. If the threshold value is higher, it is determined that the peak 35 has not been detected. If the intensity of the peak 35 is higher, the peak 35 is detected. It may be determined that it has been done.

  When the determination unit 10 determines that the connection is defective, the determination unit 10 outputs a device stop signal to the vibrator 1. The vibrator 1 stops driving when a device stop signal is input.

  Further, the type of bonding failure that can be determined by the configuration of the fourth embodiment is, as described above, a bonding failure due to vibration of the work 3 due to insufficient holding of the work 3. Therefore, in the fourth embodiment, when the determination unit 10 determines that the connection is defective, the determination unit 10 estimates that the cause of the connection failure is caused by the vibration of the work 3 due to insufficient holding of the work 3. And the cause of the bonding failure can be identified.

  Note that the method for determining the quality of the bonding quality described in the fourth embodiment can perform determination by performing FFT analysis on one or a plurality of time-divided arbitrary sections.

  As described above, according to the fourth embodiment, the frequency component of the X-direction load is determined by performing frequency analysis on the time-axis waveform of the X-direction load detected by the three-axis force detection element, and the frequency component of the X-direction load is obtained. It is configured to determine the quality of the joining quality based on whether or not a peak of a frequency that is an integral multiple of the fundamental vibration frequency that becomes a peak in the corresponding Y-direction load frequency component is detected in the X-direction load frequency component. ing.

  Accordingly, the same effect as that of the first embodiment can be obtained, and further, as a type of the bonding failure, the bonding failure due to the vibration of the workpiece due to the insufficient holding of the workpiece can be detected. .

Embodiment 5 FIG.
In a fifth embodiment of the present invention, a case will be described in which the quality of the joining quality is determined using the Z-direction load detected by the triaxial force detecting element 6. In the fifth embodiment, the description of the same points as in the first embodiment is omitted, and the points different from the first embodiment will be mainly described.

  FIG. 15 is a diagram showing a time-axis waveform of the Z-direction load in the case where no joint failure occurs according to the fifth embodiment of the present invention. FIG. 16 is a diagram showing a time-axis waveform of a Z-direction load when a bonding failure occurs in the fifth embodiment of the present invention.

  As shown in FIG. 16, when the work 3 is broken such as a chip crack, a peak 36 due to the breakage of the work 3 is seen in the time-axis waveform of the Z-direction load. In FIG. 16, only one peak 36 occurs, but a plurality of peaks 36 may occur. On the other hand, as shown in FIG. 15, when the work 3 is not damaged, the peak 36 is not seen.

  Therefore, the determination unit 10 is configured to determine the quality of the joining quality based on whether or not the peak 36 due to the breakage of the workpiece 3 is detected in the time-axis waveform of the Z-direction load. .

  Specifically, when the peak 36 is detected in the time-axis waveform of the Z-direction load, the determination unit 10 determines that the bonding is poor, and otherwise determines that the bonding is good. In addition, by investigating by various reliability tests, such as a pull test and a shear test, the peak strength which becomes a desired joining strength is set as a threshold value. Then, the threshold value is compared with the intensity of the peak 36. If the threshold value is higher, it is determined that the peak 36 has not been detected. If the intensity of the peak 36 is higher, the peak 36 is detected. It may be determined that it has been done.

  When the determination unit 10 determines that the connection is defective, the determination unit 10 outputs a device stop signal to the vibrator 1. The vibrator 1 stops driving when a device stop signal is input.

  Further, the type of bonding failure that can be determined by the configuration of the fifth embodiment is a bonding failure due to breakage of the work 3 as described above. Therefore, in the fifth embodiment, when the determination unit 10 determines that the bonding is defective, the determining unit 10 can estimate that the cause of the bonding failure is due to the damage of the work 3, and can specify the cause of the bonding failure. it can.

  As described above, according to the fifth embodiment, in the time-axis waveform of the Z-direction load detected by the three-axis force detecting element, whether the peak due to the breakage of the work is detected or not is determined. It is configured to determine pass / fail.

  Thus, the same effect as that of the first embodiment can be obtained, and further, as the type of the joining failure, the joining failure due to the breakage of the work can be detected.

  Although the first to fifth embodiments have been individually described, the configuration examples disclosed in the first to fifth embodiments can be arbitrarily combined. In each of the prior arts described in Patent Documents 1 and 2, the vibration measurement is performed only in the Y-axis direction, that is, in only one direction of the ultrasonic vibration. Therefore, it is difficult to determine the cause when a defect occurs only from the vibration waveform. Case exists. On the other hand, by appropriately combining the configuration examples of the first to fifth embodiments, it is possible to see what kind of abnormalities have occurred in the waveforms in any of the three axial directions, and it is possible to generate a bonding defect. At times, it is possible to estimate the cause of the bonding failure.

  As can be seen from the above description of the first to fifth embodiments, the wire bonding good / bad judgment device and the wire bonding good / bad judgment method of the present invention are based on the triaxial load detected by the triaxial force detecting element, that is, X. The connection quality of the wire bonding is determined based on at least one of the directional load, the Y-direction load, and the Z-direction load.

  REFERENCE SIGNS LIST 1 vibrator, 2 bonding tool, 3 work, 4 stage, 5 bonding wire, 6 3 axis force detection element, 7 charge amplifier, 8 voltage detection section, 9 analysis section, 10 determination section, 11 voltage application device, 12 voltage detection Device, 13 current detection device, 14 phase comparison device, 15 X axis direction, 16 Y axis direction, 17 Z axis direction, 18 Z direction load, 19 Y direction load, 20 X direction load, 21 Y direction waveform, 22 frequency, 23 frequency, 24 Y direction load, 25 Y direction load, 26 judgment value, 27 judgment value, 28 judgment value, 29 hour transition, 30 hour transition, 31 breakage part, 32 peak, 33 peak, 34 peak, 35 peak, 36 Peak, 101 wire bonding device, 102 wire bonding pass / fail determination device, 103 control device.

Claims (7)

A three-axis sensor that is embedded in a stage on which a workpiece is mounted and detects a load in the three-axis direction applied to the workpiece from the bonding tool when wire bonding for ultrasonically bonding a bonding wire to the workpiece is performed by the bonding tool. A force detecting element,
A control device that determines, from at least one load among the loads in the three-axis direction detected by the three-axis force detection element, whether bonding quality of the wire bonding is good or not;
With
The direction parallel to the surface of the workpiece and orthogonal to the ultrasonic vibration direction of the ultrasonic wave transmitted from the bonding tool is defined as an X-axis direction, the ultrasonic vibration direction is defined as a Y-axis direction, and the X-axis direction and the X-axis direction. When the direction orthogonal to the Y-axis direction and the bonding tool presses the bonding wire against the work when the wire bonding is performed is the Z-axis direction,
The load in the three-axis direction is constituted by an X-direction load that is the load in the X-axis direction, a Y-direction load that is the load in the Y-axis direction, and a Z-direction load that is the load in the Z-axis direction. Yes,
The control device obtains a frequency component of the Y-direction load by performing frequency analysis on a time-axis waveform of the Y-direction load detected by the three-axis force detection element, and obtains the obtained Y-direction load. A wire bonding quality determination device for determining quality of the bonding quality based on the frequency component of the wire bonding. A three-axis sensor that is embedded in a stage on which a workpiece is mounted and detects a load in the three-axis direction applied to the workpiece from the bonding tool when wire bonding for ultrasonically bonding a bonding wire to the workpiece is performed by the bonding tool. A force detecting element,
A control device that determines, from at least one load among the loads in the three-axis direction detected by the three-axis force detection element, whether bonding quality of the wire bonding is good or not;
With
The direction parallel to the surface of the workpiece and orthogonal to the ultrasonic vibration direction of the ultrasonic wave transmitted from the bonding tool is defined as an X-axis direction, the ultrasonic vibration direction is defined as a Y-axis direction, and the X-axis direction and the X-axis direction. When the direction orthogonal to the Y-axis direction and the bonding tool presses the bonding wire against the work when the wire bonding is performed is the Z-axis direction,
The load in the three-axis direction is constituted by an X-direction load that is the load in the X-axis direction, a Y-direction load that is the load in the Y-axis direction, and a Z-direction load that is the load in the Z-axis direction. Yes,
The control device includes:
By performing frequency analysis on the time-axis waveform of the Y-direction load detected by the three-axis force detection element, the frequency component of the Y-direction load is obtained,
The Y-direction load of the fundamental vibration frequency that peaks in the frequency component of the Y-direction load corresponding to the early stage of joining, and the Y-direction load of the high vibration frequency that peaks in the frequency component of the Y-direction load corresponding to the late stage of the welding By comparing a judgment value which is a ratio of the Y-direction load of the high vibration frequency with respect to the sum of the above and a predetermined judgment threshold value, it is judged whether the joining quality is good or not.
Wire bonding pass / fail determination device . The control device includes:
The wire bonding quality determination device according to claim 2, wherein the quality of the bonding quality is determined by comparing an elapsed time after the determination value exceeds the determination threshold value with a preset time threshold value. A three-axis sensor that is embedded in a stage on which a workpiece is mounted and detects a load in the three-axis direction applied to the workpiece from the bonding tool when wire bonding for ultrasonically bonding a bonding wire to the workpiece is performed by the bonding tool. A force detecting element,
A control device that determines, from at least one load among the loads in the three-axis direction detected by the three-axis force detection element, whether bonding quality of the wire bonding is good or not;
With
The direction parallel to the surface of the workpiece and orthogonal to the ultrasonic vibration direction of the ultrasonic wave transmitted from the bonding tool is defined as an X-axis direction, the ultrasonic vibration direction is defined as a Y-axis direction, and the X-axis direction and the X-axis direction. When the direction orthogonal to the Y-axis direction and the bonding tool presses the bonding wire against the work when the wire bonding is performed is the Z-axis direction,
The load in the three-axis direction is constituted by an X-direction load that is the load in the X-axis direction, a Y-direction load that is the load in the Y-axis direction, and a Z-direction load that is the load in the Z-axis direction. Yes,
The control device includes:
By performing frequency analysis on the time-axis waveform of the Y-direction load detected by the three-axis force detection element, the frequency component of the Y-direction load is obtained,
The quality of the joining quality depends on whether or not a frequency peak other than an integral multiple of the fundamental vibration frequency, which is a peak in the frequency component of the Y-direction load corresponding to the initial stage of the joining, is detected in the frequency component of the Y-direction load. Judge
Wire bonding pass / fail determination device . A three-axis sensor that is embedded in a stage on which a workpiece is mounted and detects a load in the three-axis direction applied to the workpiece from the bonding tool when wire bonding for ultrasonically bonding a bonding wire to the workpiece is performed by the bonding tool. A force detecting element,
A control device that determines, from at least one load among the loads in the three-axis direction detected by the three-axis force detection element, whether bonding quality of the wire bonding is good or not;
With
The direction parallel to the surface of the workpiece and orthogonal to the ultrasonic vibration direction of the ultrasonic wave transmitted from the bonding tool is defined as an X-axis direction, the ultrasonic vibration direction is defined as a Y-axis direction, and the X-axis direction and the X-axis direction. When the direction orthogonal to the Y-axis direction and the bonding tool presses the bonding wire against the work when the wire bonding is performed is the Z-axis direction,
The load in the three-axis direction is constituted by an X-direction load that is the load in the X-axis direction, a Y-direction load that is the load in the Y-axis direction, and a Z-direction load that is the load in the Z-axis direction. Yes,
The control device includes:
By performing frequency analysis on the time-axis waveform of the Y-direction load detected by the three-axis force detection element, the frequency component of the Y-direction load is obtained,
The frequency component of the X-direction load is obtained by performing frequency analysis on the time-axis waveform of the X-direction load detected by the three-axis force detection element,
The quality of the bonding quality is determined by whether or not a peak of an integral multiple of the fundamental vibration frequency, which is a peak in the frequency component of the Y-direction load corresponding to the initial stage of the bonding, is detected in the frequency component of the X-direction load. judge
Wire bonding pass / fail determination device . The control device includes:
The quality of the joining quality is determined based on whether a peak caused by the breakage of the work is detected in a time-axis waveform of the load in the Z direction detected by the triaxial force detection element. 6. The apparatus for determining the quality of wire bonding according to any one of claims 1 to 5. When wire bonding for ultrasonically bonding a bonding wire to a work is performed by a bonding tool, using a triaxial force detecting element to obtain a triaxial load applied to the work from the bonding tool;
Judging from the at least one load among the acquired loads in the three axial directions whether the bonding quality of the wire bonding is good or not;
With
The steps are performed by a control device,
The direction parallel to the surface of the workpiece and orthogonal to the ultrasonic vibration direction of the ultrasonic wave transmitted from the bonding tool is defined as an X-axis direction, the ultrasonic vibration direction is defined as a Y-axis direction, and the X-axis direction and the X-axis direction. When the direction orthogonal to the Y-axis direction and the bonding tool presses the bonding wire against the work when the wire bonding is performed is the Z-axis direction,
The load in the three-axis direction is constituted by an X-direction load that is the load in the X-axis direction, a Y-direction load that is the load in the Y-axis direction, and a Z-direction load that is the load in the Z-axis direction. Yes,
In the determining step, the frequency component of the Y-direction load is obtained by performing frequency analysis on the time-axis waveform of the Y-direction load detected by the three-axis force detection element, and the obtained Y direction load is obtained. A wire bonding quality determination method for determining quality of the bonding quality based on a frequency component of a load .

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