JP2001070883A - Abnormality detector of ultrasonic vibrator transducer and abnormality detection therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality detector of an ultrasonic vibrator transducer which is capable of assuring a stable vibration characteristic by detecting the abnormality with good accuracy and a method for abnormality detection therefor. SOLUTION: The data on the correlative relation between the electric power value consumed by the ultrasonic vibrator transducer 5 when driving the ultrasonic vibrator transducer 5 for imparting the vibrations to a bonding tool 2 and a drive command value is previously determined by an electric power measuring section 15 and is previously stored in a decision section 16. The electric power value is measured by the electric power measuring section 15 when driving the ultrasonic vibrator transducer 5. The result of this measurement and the data on the correlative relation described above are contrasted, by which the presence or absence of the abnormality of the ultrasonic vibrator transducer 5 is decided. As a result, the presence or absence of the abnormality of the ultrasonic vibrator transducer, such as partial disconnection or short circuit, may be decided with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device and a method for detecting an abnormality in an ultrasonic vibrator used for a bonding apparatus or the like for detecting an abnormality such as disconnection or short circuit.

[0002]

2. Description of the Related Art As a method for bonding an electronic component to a surface to be bonded such as an electrode of a substrate, a method using ultrasonic pressure welding is known. According to this method, ultrasonic vibration is applied to the electronic component while pressing the electronic component against the surface to be bonded, and the bonding surface is minutely vibrated to cause friction to bring the bonding surface into close contact. In this method, an ultrasonic transducer generally formed by laminating a plurality of piezoelectric elements is used as a vibration source. The driving of the ultrasonic transducer is performed by electrically connecting the piezoelectric elements stacked in series electrically in parallel by wiring and applying a drive voltage to each piezoelectric element.

[0003]

In order to stabilize the bonding quality, it is first necessary to stabilize the state of vibration generated by the ultrasonic vibrator. However, in the conventional ultrasonic transducer, even if the electric wiring to each piezoelectric element constituting the ultrasonic transducer is partially disconnected or short-circuited, some of the piezoelectric elements operate normally. As far as possible, the control circuit is regarded as a normal operation. For this reason, there is a problem that the bonding operation is performed without detecting a disconnection or a short circuit which is originally an abnormal state, and as a result, poor bonding quality may occur.

Accordingly, an object of the present invention is to provide an abnormality detection device and an abnormality detection method for an ultrasonic vibrator capable of accurately detecting an abnormality and securing stable vibration characteristics.

[0005]

According to a first aspect of the present invention, there is provided an abnormality detecting apparatus for ultrasonic vibration, the electric power consumed by the ultrasonic vibrator when driving the ultrasonic vibrator for applying vibration to an object to be subjected to vibration. Power measuring unit for measuring the value, the presence or absence of abnormality of the ultrasonic transducer by comparing the data of the correlation between the previously obtained power value and the drive command value and the measurement result by the power measuring unit. A determination unit for determining.

According to a second aspect of the present invention, there is provided a method for detecting an abnormality in ultrasonic vibration, wherein a power value and a drive command value consumed by the ultrasonic vibrator when driving the ultrasonic vibrator for applying vibration to an object to be subjected to vibration. The correlation data of the ultrasonic transducer is determined in advance by comparing the measurement result of the power value measured by a power measurement unit with the data of the correlation. I made it.

According to the present invention, data of the correlation between the power value consumed by the ultrasonic vibrator and the drive command value when driving the ultrasonic vibrator for applying vibration to the vibration applying object is obtained in advance. In addition, by comparing the measurement result of the power value measured by the power measurement unit and the data of the correlation, it is possible to accurately determine the presence or absence of an abnormality of the ultrasonic transducer such as partial disconnection or short circuit. it can.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ultrasonic bonding apparatus according to one embodiment of the present invention, FIG. 2 is a side view of the ultrasonic transducer, and FIG. 3 is a diagram showing power values and drive command values of the ultrasonic transducer. 6 is a graph showing the correlation of the above.

First, the configuration of the ultrasonic bonding apparatus will be described with reference to FIG. In FIG. 1, a bonding tool 2 is mounted on a lower end of a bonding head 1. The bonding tool 2 is a horizontally elongated rod, and has a crimping member 2a protruding downward from the center.
As a result, the semiconductor chip 3 is brought into contact with the upper surface of the semiconductor chip 3 to be bonded, and is pressed against the upper surface of the substrate 4 as the surface to be bonded. An ultrasonic vibrator 5 is attached to an end of the bonding tool 2, and by driving the ultrasonic vibrator 5, ultrasonic vibration is transmitted to the semiconductor chip 3 via the crimping element 2 a.

The bonding head 1 includes a bonding head driving means 6 such as a cylinder. By driving the bonding head driving means 6, the semiconductor chip 3 is pressed against the substrate 4 by the bonding tool 2. Then, by driving the ultrasonic vibrator 5 while the semiconductor chip 3 is pressed against the substrate 4, the semiconductor chip 3 is ultrasonically pressed against the substrate 4 by a load and vibration.

The ultrasonic transducer 5 is connected to an output unit 13 via an output transformer 14. The output unit 13 is the oscillation unit 1
2 and the control unit 20, and the output unit 13 amplifies the oscillation waveform sent from the oscillation unit 12 to a magnitude based on the drive command value (digital value corresponding to the voltage value) sent from the control unit 20. And outputs it to the output transformer 14. The oscillating unit 12 responds to an ON / OFF command from the control unit 20,
An oscillation waveform having a frequency corresponding to the voltage input from the frequency correction unit 10 is output to the output unit 13.

The oscillation frequency setting unit 11 outputs a voltage corresponding to the oscillation frequency preset by the control unit 20 to the frequency correction unit 10. The frequency correction unit 10 is a phase comparison unit 1
0a and an addition / subtraction unit 10b. Phase comparator 1
0a outputs a voltage corresponding to the phase difference between the voltage on the output side of the output transformer 14 and the current. This voltage is added or subtracted with the voltage output from the oscillation frequency setting unit 11, and the calculation result is output to the oscillation unit 12. As a result, the deviation from the resonance frequency of the bonding tool 2 is corrected, and the output from the output transformer 14 drives the ultrasonic transducer 5 in a state where there is no voltage / current phase difference. The output unit 13 and the output transformer 14 are connected to the ultrasonic transducer 5 based on the drive command value.
This is a vibrator driving means for driving.

A power measuring section 15 is connected to the output side of the output transformer 14, and the power measuring section 15 detects a current and a voltage on the output side to thereby obtain a power value consumed by driving the ultrasonic transducer 5. Is measured. Power measurement unit 15
Is connected to the determination unit 16. The power value measured by the power measurement unit 15 is transmitted to the determination unit 16 at predetermined intervals before and after the start of the bonding operation.

The determination section 16 previously stores data indicating the correlation between the power value measured by the power measurement section 15 and the drive command value output to the output section 13. Determines the presence or absence of an abnormality in the ultrasonic transducer 5 by comparing the power value measured at the predetermined interval with data indicating a correlation between the power value and the drive command value. The determination result is output to the control unit 20. The correlation data is obtained by measuring the power value when the control unit 20 outputs a predetermined drive command value by the power measurement unit 15 and converting the measurement result into data.

The bonding head driving section 22 drives the bonding head driving means. By controlling the bonding head driving unit 22 by the control unit 20, the operation of the bonding head driving unit 6 is controlled. The storage unit 21 stores data such as bonding conditions, that is, bonding load, bonding time, and vibrator driving power for each bonding tool and each type of semiconductor chip. Then, during the bonding operation, these data are read out to the control unit 20, and the bonding conditions are set based on these data.

Next, the structure of the ultrasonic transducer 5 will be described with reference to FIG. As shown in FIG.
Is formed by laminating a plurality of piezoelectric elements 5a, and a terminal plate 5b is sandwiched between the piezoelectric elements 5a. The terminal plate 5b is connected to the output transformer 14 by a wire 5c. Since the wiring 5c is connected in parallel to the output transformer 14 for each terminal plate 5b, even if the wiring 5c is partially disconnected, the drive current of the entire ultrasonic transducer 5 is reduced. Does not become 0, and therefore, it is not possible to detect an abnormality of the wiring 5c only by normal disconnection detection.

This ultrasonic bonding apparatus is configured as described above. Hereinafter, detection of an abnormality of the ultrasonic transducer in the ultrasonic bonding apparatus will be described. First, the data of the correlation between the power value and the drive command value stored in the determination unit 16 will be described with reference to FIG. A graph a shown in FIG. 3 shows a correlation between the drive command value output from the control unit 20 to the output unit 13 and the power consumption of the ultrasonic transducer 5 driven by the output from the output transformer 14. Things.

This graph is obtained by measuring the power value corresponding to each drive command value when the drive command value is changed at a predetermined pitch by the control unit 20 by the power measuring unit 15. Since this graph has different characteristics for each individual bonding tool, measurement is performed for each individual bonding tool of the same kind. The power measurement for obtaining this graph is performed after confirming that there is no abnormality mechanically and electrically with respect to the entire bonding tool on which the ultrasonic vibrator is mounted. That is, the graph obtained here is
The reference data indicates the correlation between the power value and the drive command value when the bonding tool is in a normal state, and is stored in the storage device of the determination unit 16. Then, an abnormality is detected based on the reference data.

Next, a description will be given of the detection of abnormalities of the ultrasonic vibrator performed when the ultrasonic bonding apparatus is operated.
When starting the ultrasonic bonding apparatus to perform the bonding operation, first, power measurement is performed before starting the bonding operation. In this power measurement, similarly to the above-described reference data acquisition, the control unit 20 outputs the drive command value to the output unit 13 while changing the drive command value at a predetermined pitch, and measures the corresponding power value for each drive command value. Determined by the unit 15. Thus, a graph showing the correlation between the power value and the drive command value in that state is obtained.

Next, this graph is compared with reference data stored in the determination unit 16, that is, a graph showing a correlation between a power value and a drive command value obtained in advance for the bonding tool. At this time, if the graph obtained as shown in FIG. 3 is included in the normal range A indicated by the hatched area, it is determined that the ultrasonic transducer 5 is operating without abnormality. On the other hand, as shown in a graph b in FIG.
If the power value falls outside the normal range A, it indicates that the power value has dropped abnormally, and it is determined that an abnormality such as partial disconnection of the wiring to the ultrasonic transducer 5 has occurred. You.

According to the present method, an abnormality other than such a partial disconnection can be detected. For example, in the case of a complete disconnection or a short circuit, the abnormality of the ultrasonic transducer 5 can be easily detected since the electric power value greatly deviates from the normal range A. Further, in addition to electrical abnormalities such as disconnection and short-circuit, according to the present method, even when mechanical abnormalities such as the mounting state of the ultrasonic transducer 5 to the bonding tool occur, the measured power value is Since the result is out of the normal range A, the abnormality can be detected in the same manner.

[0022]

According to the present invention, data of the correlation between the power value consumed by the ultrasonic vibrator and the drive command value when driving the ultrasonic vibrator for applying vibration to the object to be subjected to vibration is obtained. It is determined in advance, and the measurement result of the power value measured by the power measurement unit is compared with the data of the correlation. It can be determined well.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ultrasonic bonding apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of the ultrasonic transducer according to the embodiment of the present invention.

FIG. 3 is a graph showing a correlation between a power value and a drive command value of the ultrasonic transducer according to one embodiment of the present invention.

[Explanation of symbols]

 2 Bonding tool 3 Semiconductor chip 4 Substrate 5 Ultrasonic transducer 13 Output unit 14 Output transformer 15 Power measurement unit 16 Judgment unit 20 Control unit

Claims (2)

[Claims] A power measuring unit for measuring a power value consumed by the ultrasonic vibrator when driving the ultrasonic vibrator for applying vibration to an object to be subjected to vibration; The ultrasonic transducer, comprising: a determination unit that determines the presence or absence of abnormality of the ultrasonic transducer by comparing data of a correlation with a command value and a measurement result by the power measurement unit. Anomaly detection device. 2. The method according to claim 1, further comprising: obtaining data of a correlation between a power value consumed by the ultrasonic vibrator and a drive command value when driving the ultrasonic vibrator for applying vibration to the vibration applying target; An abnormality detection method for an ultrasonic transducer, wherein the presence or absence of an abnormality in the ultrasonic transducer is determined by comparing the measurement result of the power value measured by a measurement unit with the data of the correlation. .