JP2000137026A - Abnormality inspection method, and joining quality inspection system for wire bonding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and multiply detect the generation of abnormality in a measuring object. SOLUTION: This method is provided with an irradiation process (step S1) for irradiating respective points of a measuring object with plural laser beams oscillated by a laser beam resonator, a light receiving process (step S2) for receiving respectively the beams returned from the respective measuring points of the measuring object, which are the laser beams emitted from the irradiation process S1, and a photoelectric conversion process (S3) for converting photoelectrically respectively the laser beams received in the process S2 and self-mixed with laser beams oscillated in the resonator. A vibration quality determining process (S4) is provided also to determine the quality of vibration of the measuring object based on conditions of beat waves in the respective points of the object converted in the process S3 to be output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality inspection method and, more particularly, to a method of measuring an object by measuring the vibration of the object at various measurement points of the object by the principle of self-mixing laser vibration measurement. The present invention relates to an abnormality inspection method for inspecting an abnormality of an object. The present invention relates to a bonding quality inspection system of a wire bonding apparatus as a system suitable for carrying out this abnormality inspection method, and particularly to a bonding quality inspection of a wire bonding apparatus for connecting a wire for conducting between a silicon chip and a lead frame. About the system.

[0002]

2. Description of the Related Art Wire bonding apparatuses are IC and LSI.
This is a device that connects wires for conducting between the silicon chip, which is the core of the process, and the lead frame, and performs bonding by applying ultrasonic vibration of about 60 kHz at the same time as applying load and heating. By repeating the movement of the bonding apparatus itself, a large number of wires are connected on the chip on the fixed base.

Conventionally, there are many indirect inspection methods that have been widely used for determining the quality of bonding. Generally, inspections are conducted by applying a current or a tensile test, and a change in impedance of an ultrasonic vibrator or a delicate state of a pressurized state. Measurements have been made on changes. For example, there is a method of performing measurement from a place away from the bonding apparatus using a non-contact laser vibrometer such as argon or helium-neon.

[0004]

However, in the above-mentioned conventional example, depending on the configuration of the internal circuit of the IC, it may not be possible to perform the inspection by energization. In addition, since the tensile test is a destructive inspection, it is necessary to perform a sampling inspection. Therefore, it is impossible to perform a process such as stopping the wire bonding apparatus when a bonding failure occurs.

In the case of the measurement based on the impedance change, a change in the vibration state at the tip of the resonator called a horn is detected at the root of the horn. Similarly, even in the case of picking up a pressurized state, it is difficult to detect a change in the vibration state at the tip of the horn, for example, with a piezoelectric element installed on a fixed base of a silicon chip. When a non-contact laser vibrometer using argon, helium-neon, or the like is used, it is difficult to fix the laser head on the bonding device due to its size and weight, and cannot cope with the movement of the bonding device during continuous operation.

[0006] As described above, none of the conventional bonding quality inspection systems for wire bonding apparatuses can measure in real time whether or not bonding has actually been performed while moving integrally with the wire bonding apparatus. ,
There was an inconvenience.

[0007] In addition, the method of detecting an abnormality of an object to be measured by using a self-mixing vibration measuring device is to irradiate a laser beam from the same direction as the direction of displacement of the object to be measured. Could not be applied to a system that measures the measurement points at the same time. Then, there is an inconvenience that it is difficult to accurately and multiplexly detect occurrence of an abnormality in the measurement target.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the disadvantages of the prior art and, in particular, to provide an abnormality inspection method capable of multiplexed and accurately detecting the occurrence of an abnormality in an object to be measured. And Another object of the present invention is to provide a bonding quality inspection system capable of measuring in real time whether bonding has actually been performed while moving integrally with a wire bonding apparatus.

[0009]

Therefore, according to the present invention, there is provided an irradiation step of irradiating a plurality of laser beams oscillated by a laser resonator to each point of an object to be measured, and a method of irradiating the laser light irradiated by the irradiation step. A light receiving step of receiving return light from each measurement point of the measuring object, and a photoelectric conversion step of photoelectrically converting the laser light received in this light receiving step and self-mixed with the laser light oscillated in the resonator. ing. Moreover, a vibration quality determination step of determining the quality of vibration of the measurement object based on the state of the beat wave at each point of the measurement object converted and output in the photoelectric conversion step is adopted. I have. This aims to achieve the above-mentioned object.

In the present invention, a plurality of measurement points of a measurement object are taken and multi-point simultaneous measurement is performed. At these measurement points, one or more measurement points on the vibration surface whose normal vector coincides with the vibration direction (movement direction of displacement), measurement points that are curved, or reflected light vibrates due to the displacement of vibration. Movement in which the intersecting position of the laser light and the surface of the measurement object changes according to the vibration by irradiating the laser light from the reflection change measurement point that disappears intermittently in the cycle or the direction different from the vibration direction of the measurement object A beat wave is obtained by selecting a plurality of measurement points or measurement points that do not oscillate at all under normal conditions. When irradiating a laser beam having a constant wavelength λ, the object to be measured is λ /
When displaced by 2 lengths, a sawtooth wave is generated in the beat wave. Further, when the vibration displacement of the measurement object is smaller than λ / 2 or smaller than λ / 4, the waveform of the displacement of the measurement object is obtained. On the other hand, if a wavelength difference is provided between the oscillation wavelength and the oscillation wavelength when this laser light returns, a beat wave can be obtained in which a Doppler frequency component due to the moving speed of the measurement object is superimposed on the beat frequency due to the wavelength difference, When this beat wave is frequency-voltage converted, it becomes a velocity change waveform of the object to be measured.
As described above, a sawtooth wave, a displacement change waveform, and a speed change waveform that indicate the state of vibration can be obtained based on various beat waves. Then, the quality of the vibration is determined by analyzing the state of the waveform representing the vibration state.

As a system suitable for performing such an abnormality inspection method, there is a bonding quality inspection system of a wire bonding apparatus. The bonding quality inspection system includes an ultrasonic vibrator that oscillates ultrasonic vibration, a horn that transmits ultrasonic vibration oscillated by the ultrasonic vibrator to an object to be welded, and a horn that is attached to a tip portion of the horn. The quality of the bonding between the wire and the object to be joined is inspected by a wire bonding apparatus having a capillary that applies a load to the wire in contact with the object to be joined.

The bonding quality inspection system includes a laser resonator that irradiates a laser beam while following the movement of the measurement object using a capillary or a horn as a measurement object and receives return light from the measurement object. A light receiving element for receiving the laser light generated by the self-mixing in the laser resonator; a beat wave output means for detecting a beat wave from a signal output from the light receiving element; Signal processing means for determining whether or not there is abnormality in the vibration of the measurement object based on the beat wave.

In the bonding quality inspection system according to the present invention,
The laser resonator is integrated with the wire bonding apparatus and irradiates the measurement point with laser light following the movement of the horn and the capillary during bonding. This return light is self-mixed in the laser resonator to generate a beat wave. The beat wave output means outputs a beat wave after performing amplification, noise removal, and the like. Then, the signal processing means determines whether or not the vibration of the measurement target is abnormal based on the beat wave. For example, when the amplitude and the frequency are compared on the basis of the beat wave when the wire bonding is performed normally, abnormal vibration when the wire bonding is not performed normally is detected. For this reason, when the abnormality of the vibration of the object to be measured is detected by the signal processing means, it is determined that the bonding between the wire and the object to be bonded is defective.

[0014]

FIG. 1 is a flowchart showing the configuration of an abnormality inspection method according to the present invention. As shown in FIG. 1, the abnormality inspection method according to the present embodiment includes an irradiation step (Step S1) of irradiating a plurality of laser beams oscillated by a laser resonator to each point of an object to be measured, and an irradiation step S1.
1. A light receiving step (Step S) of receiving return light from each measurement point of the object to be measured of the laser light irradiated by Step 1
2) and a photoelectric conversion step (step S3) of photoelectrically converting the laser light received in the light receiving step S2 and oscillated in the resonator, and the laser light self-mixed. In addition, there is provided a vibration quality determination step (step S4) for determining the quality of the vibration of the measurement object based on the state of the beat wave at each point of the measurement object converted and output in the photoelectric conversion step S3. .

In the example shown in FIG. 1, a plurality of measurement points on a measurement object are irradiated with laser light simultaneously. At this time, multi-point simultaneous measurement is performed by irradiating laser beams from various directions to various measurement points according to the type of abnormality to be detected, as well as the direction in which the displacement direction of the measurement object moves. . Each laser beam is reflected at a measurement point on the measurement object, and return light enters the laser resonator. Then, the oscillation light and the return light self-mix in the resonator, and a beat wave is generated.

Referring to FIG. 2, when the displacement of the object to be measured becomes very small, the waveform of the beat wave becomes one of two states. The M-shaped state shown in FIG. 2A is a waveform when the displacement of the measuring object exceeds λ / 2, and the S-shaped state shown in FIG. / 2
Or, it is a waveform of a beat wave (small wave) when it falls below λ / 4. The waveform in the S-shape state shown in FIG. 2 (B) has been clarified by an experiment to indicate the vibration state of the measurement object as it is. Therefore, when the beat wave is in the S-shaped state, the vibration of the object to be measured can be known by directly analyzing the minute wave in the S-shaped state.

In addition to the case shown in FIG. 2, a minute wave may appear overlapping with an M-shaped wave. This occurs when, for example, the measurement object vibrates greatly and the center position slightly vibrates, for example. Even in such a case,
With respect to the minute vibration, the state of the vibration can be known by extracting the minute wave and analyzing the frequency as it is. In such extraction of a minute wave or determination of a minute wave,
Note the amplitude of the beat wave. That is, the amplitude in the state where the beat wave is in an M-shaped state or a sawtooth wave is stored, and when the amplitude of the beat wave becomes smaller than the predetermined amplitude, the entire beat wave becomes minute. It can be determined that a wave has occurred. Also, regarding the minute wave added to the sawtooth wave, when the amplitude at the upper end and the lower end of the wave is continuously lower than the amplitude of the entire sawtooth wave, the wave can be determined as a minute wave.

Next, an embodiment of the abnormality inspection apparatus according to the present invention will be described. The abnormality inspection device detects an abnormality of the measurement object 1 that vibrates in the vibration direction 7. The measuring object includes a joining device, a cutting device, a driving device, and the like used in manufacturing processes of various products. In the example shown in FIG. 3, the measurement target is a columnar object that vibrates in the left-right direction in FIG. In order to measure the vibrations at a plurality of measurement points of the measurement object, three semiconductor lasers 2 are used in the example shown in FIG. Signals output from the respective semiconductor lasers are input to the beat wave detecting means 8 respectively. Beat wave detecting means 8
In this example, an input signal is amplified by an amplifier and converted into digital data. Then, this digitized beat wave is analyzed by the arithmetic unit 14. If the beat wave is not converted to digital data, but the signal is processed as analog data to detect abnormal vibrations, processing can be performed with better responsiveness. An abnormality can be inspected in real time during operation of the apparatus. The arithmetic device is a workstation, a microcomputer, a personal computer, or the like, and includes a main storage device, a CPU, and the like.

Further, in some embodiments, a reference beat wave storage unit 16 for preliminarily storing a normal beat wave as a reference beat wave is provided in the arithmetic unit 14. By storing the beat wave in a normal state and comparing it with the beat wave being measured, occurrence of an abnormality can be detected. The arithmetic unit 14
In addition, a drive control means 18 for controlling the drive of the measuring object 1 may be additionally provided, and the driving frequency information of the measuring object may be obtained from the driving control means. Since the measurement object driven at a certain cycle vibrates at the cycle, if a breakage or a mounting failure occurs, a frequency component other than the vibration frequency component due to the drive frequency is superimposed on the beat wave, so that the drive control is performed. An abnormality can be detected by comparing the driving frequency input from the means 18 with the vibration frequency of the object to be measured.

FIG. 4 shows a configuration example of the semiconductor laser 2. The semiconductor laser 2 includes a laser resonator 4 that outputs laser light.
And a photodiode 6 for receiving light in which oscillation light and return light are self-mixed in the laser resonator 4. The laser light oscillated by the resonator 4 of the laser diode is condensed by the lens 5 and irradiated on the measurement object. By selecting lenses having different refractive indexes, the beam spot of the laser light to be irradiated can be changed.

FIG. 5 is a block diagram showing a configuration of an experimental system for observing a minute wave. Here, the state of the beat wave when the applied voltage and frequency of the function generator (FG) that vibrates the vibration source were changed was observed with the oscilloscope 52. As shown in FIG. 6, the frequency and the vibration amplitude of the PD output waveform changed in the same manner as the voltage change applied from the FG to the vibration source. When the FG applied voltage is 3 V, a sawtooth wave is generated between the turns as shown in FIG. When driven at 900 mV, the sawtooth wave begins to collapse. When driven at less than 100 mV, the beat wave enters an S-shaped state. The thick line indicating the beat wave shown in FIG. 6 is due to the influence of white noise. This figure 6
The beat waves in the S-shaped state shown in (C) to (G) are displacement change waveforms indicating a change in displacement of the measurement object. By observing the cycle of the beat wave, the oscillation cycle of the measurement object is immediately obtained. be able to.

Next, various measurement points will be described by way of example.
The irradiation step illustrated in FIG. 1 may include, for example, a step of setting the center position of the curvature in the irradiation direction when the measurement point of the measurement target is a measurement point with a curvature having a curvature. FIG.
In the example shown in FIG.
A semiconductor laser indicated by B emits laser light in a direction toward the center of the curvature of the object to be measured. The irradiation step may include a step of setting an irradiation position of the laser beam at a reflection change measurement point where the presence or absence of reflection or the reflection angle changes due to the vibration of the measurement object. In the example shown in FIG.
The semiconductor laser shown by irradiates the laser beam to the reflection change measurement point. When the reflection change measurement point is irradiated with laser light, the vibration quality determination step shown in FIG. 1 is performed based on the peak of the beat wave (see FIG. 9) corresponding to the return light from the reflection change measurement point. It is preferable to include a step of determining a cycle of the vibration of the radiator.

The irradiating step includes the step of setting the laser beam irradiation position to a moving measurement point at which the laser beam irradiation position moves in accordance with the vibration of the object 1 to be measured, and the step of setting the laser beam irradiation position to the moving measurement point by this step. When the irradiation position is set, a step of making the beam spot diameter of the laser beam larger than a reference may be provided. In the example shown in FIG. 7, the semiconductor laser indicated by reference numeral 2B irradiates the movement measurement point with laser light. This beam spot diameter is, for example, 13 in FIG.
As shown by, when the amount of vibration displacement is about twice, the influence of the movement of the measurement point due to the vibration displacement can be reduced.

In the irradiating step, an angle having a predetermined angle with respect to one direction of the vibration direction from a plane including the direction of the vibration of the object 1 to the measuring point of the object is set as the irradiation direction of the laser beam. Steps may be provided. In the example shown in FIG. 7B, the semiconductor laser 2A emits laser light from a position having a predetermined angle θ with respect to the direction 7 of the vibration displacement of the measurement object. A predetermined irradiation angle θ is defined with respect to the amplitude direction (displacement direction) of the vibration of the measurement object, and laser light is irradiated at this irradiation angle. Then, 1 / co of the moving amount of the vibration surface
Since sθ is measured, the beat wave can be in an S-shaped state.

In a self-mixing laser Doppler vibrometer,
Vibration displacement is half of laser oscillation wavelength λ 390 [nm] (when using laser whose laser oscillation wavelength is 780 [nm])
When moved, one sawtooth wave appears as an output signal.
Here, the peat wave in the sawtooth state when the vibration amplitude is λ / 2 or more is called an M-shaped state, and the beat wave that is not in the sawtooth state when the vibration amplitude is λ / 2 or less is called the S-shaped state. If the amplitude range to be measured is kept in the S-shape state by changing the laser irradiation angle when performing the measurement, the amplitude of the appearing beat wave fluctuates similarly to the vibration amplitude,
It is possible to detect a bonding failure with a change in amplitude with a simple configuration.

FIG. 8 shows an example of reflection change measurement points. FIG.
In the example shown by the solid line in FIG. 7A and FIG. 7A, the traveling destination of the reflected light on the measurement object is at an obtuse angle with respect to the semiconductor laser 2C, and there is almost no return light. On the other hand, at the positions indicated by the two-dot chain lines in FIGS. 8B and 7A, the reflected light travels at an acute angle with respect to the semiconductor laser 2C, and some return light enters the laser resonator. When such a reflection change measurement point is measured, the second waveform from the top in FIG. 9 is obtained. That is, it is a waveform in which one peak occurs in each cycle of the measurement object. The width of this peak is indicated by reference numeral 2 in FIG.
It becomes narrow as shown by Ca, and the amplitude also becomes small.
For this reason, when the reflection change measurement point is measured, the vibration cycle of the measurement object can be easily obtained.

The waveform of the semiconductor laser 2A shown in FIG. 7 is in an S-shaped state as shown in FIG. 9, and a change in amplitude can be detected. The beat wave generated by the semiconductor laser 2B shown in FIG. 7 is displayed on the same scale as the S-shaped waveform in the example shown in FIG. When the waveform of the laser head 2B is amplified, a waveform having a frequency twice that of the waveform of the laser head 2 can be obtained.

As a more specific abnormality judging method, for example, there is a method of comparing the previously measured waveform data with the currently measured waveform data, and detecting a defect based on the difference. For the waveform data to be compared, in addition to using the previous measurement data, use past typical good waveform data
Uses waveform data that has been averaged dozens or hundreds of times using good data.Uses waveform data that has been subjected to feature extraction by a neural network trained using past data. Data to be referred to can be selected according to changes in conditions such as required detection accuracy and time to detection, such as when using external input waveform data.

Further, as described above, the driving frequency of the object to be measured may be compared with the vibration frequency of the object to be measured. In this case, the vibration quality determination step shown in FIG. 1 includes a step of calculating a vibration frequency of the measurement target based on the beat wave and a step of comparing the vibration frequency with a drive frequency of a driving unit that vibrates the measurement target. And a step of determining an abnormality when the vibration frequency and the drive frequency do not match as a result of the comparison.

As described above, according to this embodiment, a self-mixing type laser that can constitute a small and lightweight laser head
Since the abnormality of the object to be measured is detected using the Doppler vibrometer, the vibration state of the object to be measured can be detected even during continuous operation. Further, by using the self-mixing type laser Doppler vibrometer, it is possible to detect an abnormality accompanied by a change in vibration amplitude (change in displacement). Further, by using the self-mixing type laser Doppler vibrometer, it is possible to detect an abnormality of the measurement object accompanied by a frequency change of the vibration of the measurement object. Further, when the simultaneous measurement is performed at multiple points as shown in FIG. 7, the accuracy of defect detection can be further improved, and the content of the abnormality can be estimated from the combination of the states of the beat waves.

In this embodiment, an abnormal state can be detected by comparing with a normal waveform, and the detection accuracy can be further improved by comparing a plurality of normal waveforms. Is possible. Further, since a large number of waveforms in a normal state can be stored in the memory, waveform processing that emphasizes the waveform itself and the characteristic points of the waveform can be added. In addition, not only the waveform itself but also data (waveform) obtained by extracting characteristics of the waveform such as an envelope, for example, can be used to increase the processing speed and reduce the weight. Further, the comparison processing performed on the frequency, the phase, and the like can be performed at high speed and simplified by using an external input waveform as a reference.

Further, reference data for determination can be selected according to conditions such as accuracy, response speed, and memory amount required for determination. By using a plurality of small laser heads at the same time, two-dimensional or three-dimensional changes in vibration can be captured. Further, an abnormal state can be detected by comparing the waveform with a typical normal waveform. Furthermore, since a large number of waveforms in a normal state can be stored in memory, for example, by using waveform processing such as averaging or neural net, it is possible to emphasize changes in the waveform itself or characteristic points of the waveform. By using not only the beat waveform itself but also (waveform) data obtained by extracting characteristics of a waveform such as an envelope, the processing speed and weight can be reduced.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a description will be given of an embodiment of a bonding inspection apparatus for a wire bonding apparatus according to the present invention. As shown in FIG. 10, in the present embodiment, an ultrasonic vibrator that oscillates ultrasonic vibration, a horn 71 that transmits the ultrasonic vibration oscillated by the ultrasonic vibrator to an object to be joined, and a horn 7
The quality of the connection between the wire and the object to be bonded is inspected by a wire bonding apparatus having a capillary 73 attached to the distal end of the device 1 and applying a load to the wire 89 in contact with the object to be bonded.

The bonding quality inspection apparatus uses the capillary 73 or the horn 71 as a measurement object to irradiate a laser beam following the movement of the measurement object and to receive a return light from the measurement object. A light receiving element 6 for receiving a laser beam generated by self-mixing in the laser resonator 2; a beat wave output means 8 for detecting a beat wave from a signal output from the light receiving element 6; A signal processing unit that determines whether or not there is an abnormality in the vibration of the measurement target based on the beat wave output by the beat wave output unit;

In the present embodiment, a laser head 2 composed of a semiconductor laser and a lens is fixed on a wire bonding apparatus, and measurement of abnormal vibration is performed together with continuous operation of bonding. The fixed position of the laser head 2 is, for example, a position extended from the capillary 73 of the wire bonding apparatus in the vibration direction of the ultrasonic vibrator, and is provided with an angle up and down so as to be in an S-shaped state as necessary. Position. For example, if the laser head is placed 20 [mm] away from the capillary, sufficient return light will be obtained and will not interfere with other devices. The capillary vibration state converted into an electric signal by the semiconductor laser is input to a signal processing unit, and information is sent to an operation device (not shown) of the wire bonding apparatus as needed.

Using the principle of self-mixing type laser Doppler vibration measurement, a small and lightweight laser head can be constructed using a semiconductor laser. Therefore, the laser head is applied to the vibration state detection of a bonding apparatus and fixed to the horn 71 or the tip of the horn. A real-time vibration monitoring system for the capillary 73 can be configured.

FIG. 11 is a perspective view showing a bonding example using the wire bonding apparatus shown in FIG. Here, IC
And a wire 81 for conducting between a terminal 83 of a silicon chip 77 serving as a core of the LSI and a lead frame 85 on a base 79. As shown in FIG.
3 is hollow, and the wires 89 are sequentially supplied.
For example, the silicon chip 77 is disposed on a base 79, and the silicon chip 77 and the base 79 are bonded with an adhesive 85.
Is fixed by Fixing stand 8 for wire bonding equipment
A jig is used for fixing the base 8 and the base 79.

FIG. 13 shows a wire bonding process. First, as shown in FIG.
Thus, a gold ball 93 is formed at the tip of the capillary. Next, as shown in FIG. 13B, the horn 71 is lowered to bond the silicon chip terminal 83 and the gold ball. This is because the tip of the capillary is moved to the position shown by the two-dot chain line in FIG.
This is performed by applying ultrasonic vibration of 60 kHz. Then, the terminals 83 of the chip 77 and the wires 81 are fixed. further,
The horn 71 is moved to the lead frame 85 side to fix the wire to the lead frame. By repeating the movement of the bonding apparatus itself, a large number of wires are connected on the chip of the fixed base as shown in FIG.

Next, the wire bonding abnormality detection processing described with reference to FIGS. 11 to 13 will be described. In the example illustrated in FIG. 10, the signal processing unit 60 has a function of determining whether there is an abnormality in the measurement target based on a change in the amplitude of the beat wave. This is because, when the silicon chip 77 and the wire are connected by the capillary 73, the energy of vibration serves as a joining work, so that the vibration amplitude of the measurement object such as the capillary 73 becomes small. For this reason, the signal processing means 60 detects abnormalities in vibration by determining whether the amplitude of the beat wave in the S-shaped state has become small, for example, at the timing when the joining is performed, and determines the quality of the joining. be able to.

Further, the bonding quality judgment system includes a reference beat wave storage unit 62 which stores a beat wave when the object to be measured vibrates normally as a reference beat wave,
The signal processing unit 60 compares the reference beat wave stored in the reference beat wave storage unit 62 with the beat wave output from the beat wave output unit 8 and determines whether the vibration of the object to be measured is good or bad according to the comparison result. May be provided. This makes it possible to quickly detect whether the increase or decrease in the vibration amplitude during joining or movement is normal.

FIG. 14 shows an example of a beat wave corresponding to capillary vibration in a good bonding state and a drive current of an ultrasonic vibrator actually measured using a self-mixing type laser Doppler vibrometer. FIG. 14A shows a drive current applied to the ultrasonic transducer, and FIG. 14B shows a beat wave in an S-shaped state. FIGS. 14C and 14D are enlarged views of the portions indicated by the two-dot chain lines in FIGS. 14A and 14B. FIG.
As shown in FIGS. 4 (C) and (D), the vibration frequency applied to the ultrasonic vibrator coincided with the frequency of the measured vibration waveform. By observing the difference between the vibration frequency applied to the ultrasonic vibrator and the frequency or cycle of the measured vibration waveform, it is possible to detect a bonding failure accompanied by a change in the vibration frequency in the same manner as in the amplitude change described above. . In this case, the signal processing means 60 has a function of determining whether or not there is an abnormality in the measurement target based on a change in the frequency of the beat wave.

More specifically, in the example shown in FIG. 10, the signal processing means 60 calculates a vibration cycle of the object to be measured based on the beat wave output from the beat wave output means, A drive cycle comparison unit is provided for comparing the cycle of the drive current of the ultrasonic vibrator with the cycle of vibration of the object to be measured, and determining whether the vibration of the object to be measured is good or not according to the comparison result. The cycle of the drive current is input from the ultrasonic transducer drive unit 61 in FIG.

FIG. 16 shows an example of measurement points when performing simultaneous multipoint measurement. Here, vibrations at various measurement points described with reference to FIGS. 7 to 9 are measured. Defect detection accuracy can be improved by measuring not only the vibration of the capillary but also the IC chip and substrate at the same time. Specifically, a capillary laser resonator (reference numeral 1) that irradiates the capillary 71 with laser light and receives return light from the capillary.
01, 102, 103, 106, 107, and 108) and a horn laser resonator (a direction indicated by reference numerals 105 and 106) that irradiates the horn 71 with laser light and receives return light from the horn. Object to be joined (for example, a work composed of a silicon chip 77 and a base 79)
Laser cavity for workpieces that irradiates laser light to the workpiece (reference numeral 10)
4, 109, 110, 111).

By using a plurality of laser heads, the planar and three-dimensional movement of the capillary can be measured. Not only the capillary, but also the horn vibration can be measured two-dimensionally or three-dimensionally. Further, the vibration of the IC chip or the substrate can be measured and utilized for improving the accuracy of the bonding judgment. For example, when the amplitude and the period of the beat wave in the S-shaped state are different in the measurement indicated by the reference numeral 102 and the reference numeral 103, as shown in FIG. Can be determined. Reference numerals 104 and 11
The vibration of the work 88 whose normal vibration is very small is measured from the directions indicated by 0 and 109, and if a beat wave is detected, it can be determined that the wire is defective or the adhesive 85 shown in FIG. 12 is defective. Further, when the measurement is performed from above the capillary (not shown) toward the capillary, it is possible to inspect the formation failure of the gold ball. FIG. 16 shows the relationship between the type of abnormality and the change of the beat wave. By combining some of the various directions shown in FIG. 15 and obtaining a vibration period at, for example, a moving measurement point, the occurrence of various abnormalities shown in FIG. 16 can be reliably detected in real time. The abnormality content can be determined from the state of a plurality of beat waves by simultaneous measurement at multiple points.

As described above, according to the present embodiment, the vibration of the horn or capillary of the wire bonding apparatus can be sensed even during continuous operation, and the vibration frequency, vibration amplitude, phase, etc. of the horn or capillary of the wire bonding apparatus can be sensed. Information on the vibration state can be stored, processed, and used as waveform data. In addition, the accuracy of defect detection can be improved by simultaneously measuring not only the vibration of the capillary but also the IC chip and the substrate.

Further, by utilizing the voltage applied to the ultrasonic transducer and the like, the comparison with the reference waveform is performed on the frequency and the phase, so that a high-speed and simple processing can be determined. In addition, reference data for determination can be selected according to conditions such as accuracy, response speed, and memory amount required for determination. By using a plurality of small and lightweight laser heads at the same time, vibration of a horn, a capillary, or the like can be captured two-dimensionally or three-dimensionally.

[0047]

Since the present invention is constructed and functions as described above, according to this, the irradiation step irradiates a plurality of measurement points with laser light, so that a plurality of measurement points of the measurement object are taken.
Multipoint simultaneous measurement can be performed, for example, a vibration surface whose normal vector is equal to the vibration direction, a measurement point that is a curved surface, a reflection change measurement point, a moving measurement point, and in the case of normal, A beat wave can be obtained by selecting a plurality of measurement points that do not vibrate at all, and a vibration quality determination step includes a displacement change waveform and a speed change waveform corresponding to the beat wave corresponding to each measurement point. In order to judge the quality of the vibration from the above, it is possible to provide an unprecedented superior abnormality inspection method in which the abnormal vibration can be immediately detected when a vibration different from the normal vibration of the measurement object occurs. .

Further, in the bonding quality inspection system of the wire bonding apparatus according to the present invention, when the laser resonator irradiates the measurement point with laser light following the movement of the horn and the capillary, the return light is transmitted into the laser resonator. The beat wave is generated by self-mixing, and the signal processing means determines whether or not the vibration of the object to be measured is abnormal based on the beat wave. Can detect abnormalities in the vibration of the object to be measured.In particular, if there is a problem such as improper attachment of the capillary or poor joining of the workpiece, the vibration will be different from the normal one. If it is detected, it will be inspected for bonding failure, and it is small and light because of the configuration that generates a beat wave in the laser resonator. It is possible to provide a no good bonding failure inspection system prior being able to measure whether the bonding is performed in real time during.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a configuration of a first embodiment of the present invention.

FIGS. 2A and 2B are waveform diagrams showing changes in the state of a beat wave. FIG. 2A shows an example of an M-shaped state, and FIG. 2B shows an example of an S-shaped state.

FIG. 3 is a block diagram showing a configuration of a vibration measuring device according to the present invention.

FIG. 4 is an explanatory diagram illustrating an example of a detailed configuration of a light detection unit illustrated in FIG. 3;

FIG. 5 is a block diagram showing a configuration of an experimental system for observing a state of a beat wave when a measurement object performs minute vibration.

FIG. 6 is a waveform diagram showing the state of a beat wave when the vibration frequency is specified as 10 [kHz] and the FG applied voltage is changed, and FIGS.
It is a figure which shows the state of a beat wave in the case of [V]-20 [mV].

FIG. 7 is an explanatory diagram showing an example of measuring vibration at a measurement point having a curvature, a measurement point at which reflected light changes, and a measurement point irradiated with laser light at a predetermined angle; ) Is a plan view, and FIG. 7B is a right side view.

8A and 8B are explanatory diagrams illustrating an example in which a measurement point at which reflected light changes is irradiated with laser light. FIG. 8A illustrates an optical path of the laser light in a state indicated by a solid line in FIG. FIG. 8
FIG. 7B is a diagram illustrating an optical path of the laser light in a state indicated by a two-dot chain line in FIG.

9 is a waveform diagram showing an example of a beat wave output from each laser resonator shown in FIG.

FIG. 10 is a block diagram showing a configuration of a bonding quality inspection system of the wire bonding apparatus according to the present invention.

11 is a perspective view showing an example of a bonding target of the wire bonding apparatus shown in FIG.

FIG. 12 is an enlarged view showing details of a capillary shown in FIG. 10;

FIGS. 13A to 13C are explanatory diagrams illustrating an example of a wire bonding operation in the wire bonding apparatus illustrated in FIG. 10;

14 is a diagram showing an example of a vibrator driving current and a beat wave used in the configuration shown in FIG. 10; FIG. 14A is a diagram showing an example of a vibrator driving current waveform; FIG. FIG. 14 (C) is an enlarged view of a position indicated by a two-dot chain line in FIG. 14 (A), and FIG.
FIG. 4B is an enlarged view of a position indicated by a two-dot chain line in FIG.

FIG. 15 is a perspective view showing an example of measurement points and measurement light when performing simultaneous multipoint measurement.

FIG. 16 is a table showing a relationship between types of abnormalities in wire bonding and changes in beat waves corresponding to the abnormalities.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement object 2 Laser element 4 Laser diode (resonator) 6 Photodiode 8 Beat wave detection means 10 Amplifier 12 A / D converter 14 Operation device 16 Reference beat wave storage part 18 Drive control means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G047 AB07 AC10 BA04 BC00 BC04 BC05 CA04 GD00 GG09 GG19 4M106 AA14 BA05 CA33 DH05 DH12 DH20 DH32 DJ21 5F044 JJ01

Claims (12)

[Claims] 1. An irradiation step of irradiating a plurality of laser beams oscillated by a laser resonator to each point of a measurement object, and a step of irradiating the laser light irradiated by the irradiation step from each measurement point of the measurement object. A light-receiving step of receiving the return light, and a photoelectric conversion step of photoelectrically converting the laser light received in the light-receiving step and the self-mixed laser light in the resonator and the self-mixed laser light. An abnormality inspection method, comprising: a vibration quality determination step of determining the quality of vibration of the measurement object based on a state of a beat wave at each point of the measurement object that is converted and output. 2. The method according to claim 1, wherein the irradiating step includes a step of setting a center position of the curvature in an irradiation direction when the measurement point of the measurement object is a measurement point with a curvature having a curvature. The abnormality inspection method according to claim 1. 3. The irradiation step includes a step of setting an irradiation position of the laser beam at a reflection change measurement point at which the presence or absence of reflection or a reflection angle changes due to the vibration of the measurement object. 2. The abnormality inspection method according to claim 1, further comprising a step of determining a vibration cycle of the measurement object based on a peak of a beat wave corresponding to light returned from the reflection change measurement point. 4. The irradiating step includes: setting a laser beam irradiation position at a moving measurement point at which the laser beam irradiation position moves in accordance with the vibration of the measurement object; 2. The abnormality inspection method according to claim 1, further comprising the step of: setting a beam spot diameter of the laser beam larger than a reference when a light irradiation position is set. 5. The method according to claim 1, wherein the step of irradiating the laser beam with an angle having a predetermined angle with respect to one direction of the vibration direction from a plane including the direction of vibration of the measurement object to a measurement point of the measurement object. 5. The abnormality inspection method according to claim 1, further comprising a setting step. 6. The vibration quality determination step includes calculating a vibration frequency of the measurement target based on the beat wave, and comparing the vibration frequency with a drive frequency of a driving unit that vibrates the measurement target. 2. The abnormality inspection method according to claim 1, further comprising a step and a step of determining an abnormality when the vibration frequency and the drive frequency do not match as a result of the comparison. 7. An ultrasonic vibrator for oscillating ultrasonic vibration,
A wire bonding apparatus having a horn for transmitting ultrasonic vibrations oscillated by the ultrasonic vibrator to an object to be joined, and a capillary attached to a tip portion of the horn and applying a load to a wire in contact with the object to be joined; In a bonding quality inspection system for inspecting the quality of bonding between the object and the bonding target, the capillary or horn is used as a measurement target, the laser beam is irradiated following the movement of the measurement target, and return from the measurement target is performed. A laser resonator that receives light, a light receiving element that receives laser light generated by self-mixing in the laser resonator, and a beat wave output unit that detects a beat wave from a signal output from the light receiving element, A signal for determining the presence or absence of abnormal vibration of the object to be measured based on the beat wave output by the beat wave output means. And a signal processing means. 8. The joint quality inspection system according to claim 7, wherein said signal processing means has a function of determining the presence or absence of an abnormality in said measurement target based on a change in amplitude of said beat wave. . 9. A reference beat wave storage unit that stores a beat wave when the measurement object vibrates normally as a reference beat wave, and a reference beat wave stored in the reference beat wave storage unit. A vibration quality determination unit that compares a beat wave with a beat wave output from the beat wave output unit and that determines a quality of a vibration of the measurement object according to the comparison result. 7. The bonding quality inspection system according to 7 or 8. 10. The apparatus according to claim 7, wherein the signal processing means has a function of determining whether or not the measurement target is abnormal based on a change in the frequency of the beat wave. Bonding quality inspection system. 11. A vibration cycle calculating section for calculating a vibration cycle of the object to be measured based on a beat wave output by the beat wave output means, and a driving current of the ultrasonic vibrator. The joint quality inspection according to claim 10, further comprising a drive cycle comparison unit that compares a cycle with a vibration cycle of the measurement object and determines whether the vibration of the measurement object is good or not according to the comparison result. system. 12. An ultrasonic vibrator for oscillating ultrasonic vibration, a horn for transmitting ultrasonic vibration oscillated by the ultrasonic vibrator to an object to be joined, and a horn attached to a tip portion of the horn and connected to the object to be joined. In a bonding quality inspection system for inspecting the quality of bonding between a wire and an object to be bonded by a wire bonding apparatus having a capillary for applying a load to a wire in contact with an object, a laser beam is applied to the capillary and return light from the capillary is applied. , A horn laser resonator that irradiates the horn with laser light and receives return light from the horn, and a work laser resonator that irradiates the joining object with laser light. And a self-mixing of the laser light irradiating means in each laser resonator. A light receiving element for receiving the laser light generated by the light receiving means, a beat wave output means for detecting a beat wave from a signal output from the light receiving element, and the measurement object based on a plurality of beat waves output by the beat wave output means A bonding quality inspection system, comprising: a vibration abnormality determining unit that determines whether or not there is a vibration abnormality of an object.