JP3613087B2 - Abnormality detection apparatus and abnormality detection method for ultrasonic transducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an abnormality detection apparatus and an abnormality detection method for an ultrasonic transducer that detects an abnormality such as a disconnection or a short circuit in an ultrasonic transducer used in a bonding apparatus or the like.
[0002]
[Prior 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. In this method, ultrasonic vibration is applied to the electronic component while pressing the electronic component against the surface to be joined, and the joining surface is brought into close contact by causing the joining surface to vibrate minutely to generate friction. In this method, an ultrasonic transducer generally formed by laminating a plurality of piezoelectric elements is used as a vibration generation source. The ultrasonic vibrator is driven by electrically connecting the piezoelectric elements stacked in series in parallel by wiring and applying a driving voltage to each piezoelectric element.
[0003]
[Problems to be solved by the invention]
By the way, 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 electrical wiring to each piezoelectric element constituting the ultrasonic transducer is partially broken or short-circuited, some of the piezoelectric elements are operating normally. As long as it was regarded as a normal operation on the control circuit. For this reason, there has been a problem that the bonding operation is performed without detecting a disconnection or a short circuit which is originally in an abnormal state, resulting in a defective bonding quality.
[0004]
Accordingly, an object of the present invention is to provide an abnormality detection device and an abnormality detection method for an ultrasonic transducer capable of accurately detecting an abnormality and ensuring stable vibration characteristics.
[0005]
[Means for Solving the Problems]
The abnormality detection apparatus for ultrasonic vibration according to claim 1, wherein the power consumed by the ultrasonic vibrator when driving the ultrasonic vibrator for applying vibration to the vibration application object at the resonance frequency of the vibration application object. By comparing the power measurement unit for measuring the value, the correlation data between the power value and the drive command value obtained in advance and the measurement result by the power measurement unit, the presence or absence of abnormality of the ultrasonic transducer is determined. And a determination unit for determining.
[0006]
The abnormality detection method for ultrasonic vibration according to claim 2, wherein the power consumed by the ultrasonic vibrator when driving the ultrasonic vibrator for applying vibration to the vibration application target at the resonance frequency of the vibration application object. The correlation between the value and the drive command value is obtained in advance, and the measurement result of the power value measured by the power measurement unit is compared with the correlation data, whereby the abnormality of the ultrasonic transducer is detected. The presence or absence of was judged.
[0007]
According to the present invention, 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 application object at the resonance frequency of the vibration application object. Preliminarily obtain the relationship data, and by comparing the measurement result of the power value measured by the power measurement unit and the correlation data, whether there is an abnormality in the ultrasonic transducer such as a partial disconnection or short circuit It can be determined with high accuracy.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an ultrasonic bonding apparatus according to an embodiment of the present invention, FIG. 2 is a side view of the ultrasonic transducer, and FIG. 3 shows power values and drive command values of the ultrasonic transducer. It is a graph which shows correlation of these.
[0009]
First, the configuration of the ultrasonic bonding apparatus will be described with reference to FIG. In FIG. 1, a bonding tool 2 is attached to the lower end portion of the bonding head 1. The bonding tool 2 is a horizontally elongated bar, and is brought into contact with the upper surface of the semiconductor chip 3 as a bonding target by a crimping member 2a projecting downward from the center portion to be a bonded surface. Press against the upper surface of the substrate 4. An ultrasonic vibrator 5 is attached to the end portion of the bonding tool 2, and the ultrasonic vibration is transmitted to the semiconductor chip 3 through the crimper 2 a by driving the ultrasonic vibrator 5.
[0010]
The bonding head 1 includes a bonding head driving unit 6 such as a cylinder, and the semiconductor chip 3 is pressed against the substrate 4 by the bonding tool 2 by driving the bonding head driving unit 6. Then, by driving the ultrasonic transducer 5 in a state where the semiconductor chip 3 is pressed against the substrate 4, the semiconductor chip 3 is ultrasonically pressed against the substrate 4 by load and vibration.
[0011]
The ultrasonic transducer 5 is connected to the output unit 13 via the output transformer 14. The output unit 13 is connected to the oscillation unit 12 and the control unit 20. The output unit 13 converts the oscillation waveform sent from the oscillation unit 12 into a drive command value (digital value corresponding to the voltage value) sent from the control unit 20. The signal is amplified to a size based on the output and output to the output transformer 14. The oscillation unit 12 outputs an oscillation waveform having a frequency corresponding to the voltage input from the frequency correction unit 10 to the output unit 13 in accordance with an ON / OFF command from the control unit 20.
[0012]
The oscillation frequency setting unit 11 outputs a voltage according to the oscillation frequency preset by the control unit 20 to the frequency correction unit 10. The frequency correction unit 10 includes a phase comparison unit 10a and an addition / subtraction calculation unit 10b. The phase comparison unit 10a 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 to or subtracted from the voltage output from the oscillation frequency setting unit 11, and the calculation result is output to the oscillation unit 12. Thereby, 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 serve as a vibrator driving unit that drives the ultrasonic vibrator 5 based on a drive command value.
[0013]
A power measuring unit 15 is connected to the output side of the output transformer 14, and the power measuring unit 15 measures a power value consumed by driving the ultrasonic transducer 5 by detecting current and voltage on the output side. . A determination unit 16 is connected to the power measurement unit 15. 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.
[0014]
In the determination unit 16, data indicating the correlation between the power value measured by the power measurement unit 15 and the drive command value output to the output unit 13 is obtained and stored in advance, and the determination unit 16 stores the predetermined value. By comparing the power value measured at this interval with data indicating the correlation between the power value and the drive command value, the presence or absence of abnormality of the ultrasonic transducer 5 is determined. 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 measuring unit 15 and converting the measurement result into data.
[0015]
The bonding head drive unit 22 drives the bonding head drive means. By controlling the bonding head drive unit 22 by the control unit 20, the operation of the bonding head drive unit 6 is controlled. The storage unit 21 stores data such as bonding conditions, that is, bonding load, bonding time, vibrator driving power, and the like for each bonding tool and each type of semiconductor chip. During the bonding operation, these data are read out to the control unit 20, and bonding conditions are set based on these data.
[0016]
Next, the structure of the ultrasonic transducer 5 will be described with reference to FIG. As shown in FIG. 2, the ultrasonic transducer 5 is configured by laminating a plurality of piezoelectric elements 5a, and a terminal plate 5b is sandwiched between the piezoelectric elements 5a. The terminal board 5b is connected to the aforementioned output transformer 14 by wiring 5c. Since the wiring 5c is connected to the output transformer 14 in parallel for each terminal board 5b, even if the wiring 5c is partially disconnected, the drive current of the ultrasonic transducer 5 as a whole Therefore, the abnormality of the wiring 5c cannot be detected only by normal disconnection detection.
[0017]
This ultrasonic bonding apparatus is configured as described above, and abnormality detection of the ultrasonic transducer in the ultrasonic bonding apparatus will be described below. First, the correlation data between the power value stored in the determination unit 16 and the drive command value 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. Is.
[0018]
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 using the power measurement unit 15. Since this graph has different properties for each individual bonding tool, measurement is performed for each individual bonding tool of the same type. The power measurement for obtaining this graph is performed after confirming that there is no abnormality mechanically and electrically for the entire bonding tool on which the ultrasonic transducer is mounted. That is, the graph obtained here is reference data indicating 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, abnormality detection is performed based on the reference data.
[0019]
Next, the abnormality detection of the ultrasonic transducer performed when the ultrasonic bonding apparatus is operated will be described. When starting the ultrasonic bonding apparatus and performing bonding work, power measurement is first performed before the bonding operation is started. In this power measurement, the control unit 20 outputs the drive command value to the output unit 13 while changing it at a predetermined pitch in the same manner as the above-described reference data acquisition, and the power value corresponding to each drive command value is measured. Determined by part 15. Thereby, a graph showing the correlation between the power value and the drive command value in that state is obtained.
[0020]
Next, this graph is compared with the reference data stored in the determination unit 16, that is, the graph showing the correlation between the power value obtained in advance for the bonding tool and the drive command value. At this time, if the graph obtained as shown in FIG. 3 is included in the normal range A indicated by the hatched range, it is determined that the ultrasonic transducer 5 is operating without abnormality. On the other hand, as shown in the graph b shown in FIG. 3 , when the value deviates downward from the normal range A, it indicates that the power value is abnormally decreased, and the wiring of the ultrasonic transducer 5 It is determined that an abnormality such as a partial disconnection has occurred.
[0021]
According to the present method, it is possible to detect an abnormality other than such a partial disconnection. For example, in the case of a complete disconnection or a short circuit, the power value appears greatly deviating from the normal range A, so that the abnormality of the ultrasonic transducer 5 can be easily detected. Further, in addition to electrical abnormalities such as disconnection and short circuit, according to the present method, even when a mechanical abnormality such as the attachment state of the ultrasonic vibrator 5 to the bonding tool occurs, the power measurement value is Since the result is out of the normal range A, it is possible to detect an abnormality similarly.
[0022]
【The invention's effect】
According to the present invention, 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 application object at the resonance frequency of the vibration application object. Since the relationship data is obtained in advance and the measurement result of the power value measured by the power measurement unit is compared with the correlation data, abnormalities in the ultrasonic transducer such as partial disconnection or short circuit The presence or absence of can be determined with high accuracy.
[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 an ultrasonic transducer according to an embodiment of the present invention. Showing the correlation between the power value and drive command value of an ultrasonic transducer in the form of
2 Bonding tool 3 Semiconductor chip 4 Substrate 5 Ultrasonic transducer 13 Output unit 14 Output transformer 15 Power measurement unit 16 Determination unit 20 Control unit

Claims (2)

A power measuring unit that measures a power value consumed by the ultrasonic vibrator when driving the ultrasonic vibrator for applying vibration to the vibration applying object at a resonance frequency of the vibration applying object; And a determination unit that determines whether or not there is an abnormality in the ultrasonic transducer by comparing data of a correlation between a power value and a drive command value and a measurement result of the power measurement unit. Abnormality detection device in a sound wave vibrator. The correlation data between the power value consumed by the ultrasonic transducer and the drive command value when driving the ultrasonic transducer that applies vibration to the vibration application target at the resonance frequency of the vibration application target is obtained in advance. The ultrasonic transducer is characterized by determining whether or not the ultrasonic transducer is abnormal by comparing the measurement result of the power value measured by the power measuring unit with the correlation data. Anomaly detection method.

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