JP2012107918A - Crack detection device and crack detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crack detection device capable of accurately detecting a location of crack occurrence through measurement of frequency variation in an ultrasonic band radiated from a crack located within a measuring object which is floated and vibrated in the air.SOLUTION: A crack detection device A vibrates a whole area of a diaphragm 20 in a primary vibration mode in a unified cycle, so that a sound flow of compressional waves at a single frequency in an ultrasonic band is radiated at a predetermined sound pressure level at an arbitrarily-designed resonance frequency, allowing the measuring object 25 to be floated and vibrated on one surface of the diaphragm 20 in response to the wavelength of the resonance frequency. A sensing part 30 of the device A determines crack occurrence in the measuring object 25 when frequency characteristic variation is detected in the detected and measured sound flow.

Description

  The present invention uses an acoustic flow with a strong sound pressure level in the frequency band in the ultrasonic region, and cracks (for example, internal flaws and defects, internal empty walls, internal cavities, etc.) existing in measurement objects such as solar cells. The present invention relates to a crack detection apparatus and a crack detection method that can accurately detect various defects present in a measurement object.

  Conventionally, there are apparatuses and methods for detecting cracks in a semiconductor substrate by ultrasonic flaw detection. As such, “Place the object to be measured in water or other liquid, scan the probe over it, send and receive sound waves from it, and detect the abnormal part directly under the probe on the secondary plane. Alternatively, there is proposed an ultrasonic flaw detection method in which an arbitrary cross section is displayed in a quadratic plane, and a silicon lump flaw detection method in which the object to be measured is a polycrystalline silicon lump and the flaw detection frequency is 0.5 to 10 MHz is proposed ( For example, see Patent Document 1). This flaw detection method utilizes the characteristic of ultrasonic waves, that is, the characteristic that attenuation is low in water or liquid.

JP 2001-21543 A (3rd page, FIG. 1 etc.)

  In the technique described in Patent Document 1, ultrasonic waves in a high frequency band of 0.5 to 10 MHz are generated in order to detect small cracks existing in a silicon mass that is a measurement object. Moreover, in order not to attenuate the sound pressure level of the generated ultrasonic wave, it is performed in water or liquid. However, in such a method, when the measurement object is a thin film such as a solar cell, there is a possibility that the measurement object is further damaged during the operation of putting the measurement object into or out of water or liquid. there were.

  Moreover, since the frequency of the generated ultrasonic wave is high, the amplitude is inevitably small. Therefore, it is possible to detect fine cracks by detailed analysis, but it is necessary to scan the measurement object finely according to the frequency amplitude, and it takes a lot of time to scan the surface of the measurement object. There is.

  Therefore, a general piezoelectric element using PZT (lead zirconate titanate) that can emit a strong sound pressure level in an ultrasonic frequency band lower than the frequency of the technique described in Patent Document 1 is used. It is conceivable to use an ultrasonic generator. Then, by utilizing the “acoustic flow” of the sound pressure level by powerful ultrasonic waves, the measurement object is floated and vibrated in the air at an arbitrary height, thereby detecting a crack in the measurement object. Specifically, the acoustic radiation characteristics generated from cracks and internal defects present in the measurement object, or the sound pressure level attenuation of the frequency in the ultrasonic band that attenuates in the air layer such as the internal empty wall should be measured. Then, the crack of the measurement object is detected.

  A general ultrasonic generator oscillates a piezoelectric element by applying a voltage to the piezoelectric element and acoustically oscillates a specific frequency by using a resonance frequency of vibration in a certain direction. In such an ultrasonic generator, the frequency generated by the piezoelectric element generally has an ultrasonic range of 18 kHz or higher that is different from the frequency of the audible range, and the sound pressure level is emitted into the air. The sound pressure level is extremely attenuated. Therefore, in order to amplify the sound pressure level, a resonance structure (horn structure) is attached to the surface vibration direction of the piezoelectric element so that the frequency of the surface vibration of the piezoelectric element matches the frequency of the resonance structure. There are many cases.

  However, since a strong sound pressure level is generated only at the tip of the horn, there is a problem in that a measurement object having an arbitrary area cannot be lifted uniformly or transmitted through the entire measurement object uniformly in a short time. was there.

  The present invention has been made to solve the above-described problems. The measurement object is floated, vibrated in the air, and the frequency fluctuation of the ultrasonic band radiated from a crack existing inside the measurement object is achieved. It is intended to provide a crack detection device and a crack detection method that can accurately detect the location where a crack occurs by measuring the above.

  The crack detection device according to the present invention is formed of an ultrasonic transducer that generates ultrasonic waves in a predetermined frequency band, and a square metal material having an arbitrary area and arbitrary thickness, and one surface of the ultrasonic transducer is A diaphragm attached to one end, and sensing means for detecting and measuring spatial radiated sound in an arbitrary ultrasonic band generated from the measurement object, and the diaphragm has a natural frequency exceeding the supersonic frequency. It matches the natural frequency of the ultrasonic vibrator, causes vibration and resonance phenomenon of the ultrasonic vibrator, and vibrates the entire surface in the form of a primary vibration mode with the same period. An acoustic stream that is a dense wave with a single frequency in the sonic band is radiated at a predetermined sound pressure level, and the object to be measured is levitated and vibrated on the other surface according to the wavelength of the resonance frequency. .

  The crack detection method according to the present invention generates an ultrasonic wave of a predetermined frequency band using an ultrasonic vibrator, is formed of a square metal material having an arbitrary area and an arbitrary thickness, and one surface thereof is the ultrasonic vibration. Using a diaphragm attached to one end of a child, matching the natural frequency of the diaphragm with the natural frequency of the ultrasonic vibrator, causing a resonance phenomenon with the ultrasonic vibrator, and the vibration The entire surface of the plate is vibrated in the form of a primary vibration mode with the same period, and an acoustic flow that is a dense wave with a single frequency in the ultrasonic band is radiated at a predetermined sound pressure level at an arbitrarily designed resonance frequency. The object is levitated and vibrated on the other surface of the diaphragm portion according to the wavelength of the resonance frequency, and the spatial radiation sound of an arbitrary ultrasonic band generated from the measurement object is detected and measured using the sensing means. Levitation measurement object Wherein by measuring the frequency variation of the acoustic flow between the diaphragm portion, and detecting the presence or absence and presence position of cracks in the measurement object and.

  According to the crack detection device and the crack detection method according to the present invention, it is possible to radiate high sound pressure ultrasonic waves from the diaphragm, and it is possible to stably vibrate the measurement object in the air. In particular, a sound can be generated from a measurement object having cracks.

It is the schematic which shows the whole system of the ultrasonic generator of the crack detection apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the result of having measured an actual vibration state and analyzing the vibration mode state. It is a schematic diagram which shows typically the state of the vibration mode in which the diaphragm part is vibrating uniformly. It is the schematic which shows the whole system of a crack detection apparatus. It is explanatory drawing for demonstrating the sound radiation state of a crack detection apparatus, and the floating state of a measuring object. It is explanatory drawing which shows typically distribution of the sound radiation state of the to-be-measured object. It is explanatory drawing which shows the sound radiation characteristic before the detection of a crack. It is explanatory drawing which shows the sound radiation characteristic when the crack which exists in a measuring object is detected.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an entire system of an ultrasonic generator 100 of a crack detection apparatus A according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of a result obtained by measuring the actual vibration state and analyzing the vibration mode state. FIG. 3 is a schematic diagram schematically showing the state of the vibration mode in which the diaphragm 20 is vibrating uniformly. The ultrasonic generator 100 which comprises the crack detection apparatus A is demonstrated based on FIGS. In addition, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

  The ultrasonic generator 100 generates a dense wave with a strong sound pressure level by oscillating an ultrasonic vibrator. The ultrasonic generator 100 includes a plurality of piezoelectric elements 10 such as PZT (lead zirconate titanate) sandwiched between holding parts 11 made of a metal material such as aluminum and fixed. 12 is provided. The ultrasonic transducer 12 is entirely applied by applying a pulse voltage to the piezoelectric element 10 and propagating a single vibration frequency of 18 kHz or more generated by the oscillation of the piezoelectric element 10 to the holding unit 11. Vibrates in one ultrasonic band. Note that an ultrasonic transducer such as this structure generally oscillates in the ultrasonic band of 18 kHz to 50 kHz.

  A diaphragm portion 20 is attached to one end of the ultrasonic transducer 12. The diaphragm 20 is fixed to one end of the ultrasonic transducer 12 using at least one of fixing members such as an adhesive and a screw. The ultrasonic generator 100 is designed so that the natural frequency generated by the ultrasonic transducer 12 is, for example, 25 kHz, and the vibration plate unit 20 has a primary natural frequency that vibrates at 25 kHz. That is, the ultrasonic generator 100 has a structure design in which the natural frequency of the ultrasonic transducer 12 and the natural frequency of the diaphragm 20 are matched.

  In this structural design, in particular, a rectangular shape (specifically, a square shape in which the primary natural frequency is 25 kHz when the material (for example, aluminum) constituting the diaphragm portion 20 is subjected to center excitation at the stage of designing the rectangular shape. ) And its thickness.

The determining factor is as shown in the following formula.

In the above equation, λ is the vibration coefficient of the diaphragm 20, l is the distance (mm) from the fixed point of the diaphragm 20 (contact center point with the ultrasonic transducer 12), and E is the diaphragm 20. Young's modulus of the material (if the material is an aluminum 70.6GPa), I is the second moment in longitudinal section of the diaphragm portion ^{20 (bh 3/12),} d the structure of the diaphragm portion 20 The density of the material (2.68 kg / m ³ if the constituent material is aluminum), A is the cross-sectional area (b × h) in the longitudinal section of the diaphragm portion 20, and b is the width (one side of the diaphragm portion 20). Length: mm (for example, 200 mm)), and h represents the height (thickness: mm) of the diaphragm 20.

  By completely fixing the diaphragm 20 designed by the above formula to the ultrasonic vibrator 12, the diaphragm 20 vibrates as a primary natural vibration in an ultrasonic band in which the respective natural frequencies coincide with each other. The vibration mode of the diaphragm 20 at this time is a regular vibration mode state having “sparse” and “dense” portions as shown in FIG. This vibration mode has a vibration distribution in which the left and right and upper and lower sides are bent with the center of the diaphragm 20 (the center of the diaphragm 20 at the portion where the ultrasonic transducer 12 is fixed) as a base point (shown in FIG. 1). Dotted line a). Further, the vibration distribution is such that it is bent in a triangular shape so that the corners of the diaphragm 20 are aligned (dotted line b shown in FIG. 1).

  Therefore, this vibration mode is tentatively referred to as “square + triangular vibration mode” based on the ultrasonic vibrator 12 that vibrates and vibrates the center of the diaphragm portion 20. A portion where the rectangular vibration mode and the triangular vibration mode intersect (portions other than the dotted line a and the dotted line b shown in FIG. 1) becomes a vibration “antinode”, and this “antinode” portion indicates the vibration speed and the vibration displacement amount. Is the “dense” part. On the other hand, the portion other than the portion where the square vibration mode and the triangular vibration mode intersect (dotted line a and dotted line b shown in FIG. 1) becomes the vibration “node”, and this “node” portion is the vibration velocity and vibration. The displacement is the sparse part.

  From FIG. 2, it can be seen that in the “square + triangular vibration mode”, a large vibration amplitude is generated in the portion corresponding to the “belly” of the diaphragm 20. In a portion corresponding to this “belly”, a vibration speed corresponding to 1 m / sec is generated. On the other hand, it can be seen that almost no vibration amplitude is obtained at the portion corresponding to the “node” of the diaphragm 20. That is, the vibration amplitude of the vibration plate portion 20 is greatly generated in a portion corresponding to “antinode” = dense, and is hardly obtained at other portions (portion corresponding to “node” = sparse). It is.

  This shows that the same vibration state can always be obtained as long as the vibration frequency of the ultrasonic band in the piezoelectric element 10 does not change. As will be described later, this also means that it is possible to obtain pressure fluctuation = “acoustic flow” caused by a strong sound pressure level accompanying vibration amplitude for stably levitating the measurement object. As shown in FIG. 1, the diaphragm 20 radiates vibrations at uniform distance intervals throughout the diaphragm 20 with the center of the diaphragm 20 as a base point. That is, the diaphragm 20 repeats vibration in the front and back directions at the vibration portion that becomes the “belly”. Therefore, in the diaphragm portion 20, a phenomenon that always repeats a constant vibration mode occurs.

  FIG. 3 schematically shows a form of “dense / dense wave” that is generated when the diaphragm 20 vibrates uniformly in the “square + triangular vibration mode”. Further, in FIG. 3, the sound radiated from the entire surface of the diaphragm 20 to the air with a certain directivity from the dense portion of the “dense wave” in the vibration state of the diaphragm 20 to the air. A “dense wave” state is also schematically shown. As shown in FIG. 3, sound density waves are generated (formed) in a period corresponding to the wavelength of the ultrasonic band frequency generated in the diaphragm 20, and the intervals between density waves are uniformly stable. It has become. In FIG. 3, regarding the “sparse / dense wave” state of the sound, the surface side of the ultrasonic transducer 12 that is not the fixed side is illustrated.

  As described above, the diaphragm 20 and the ultrasonic vibrator 12 vibrate at the same natural frequency, and the vibration in the ultrasonic band generated by the plurality of piezoelectric elements 10 has a strong vibration speed. become. The vibration speed reaches 1 m / sec. Since an equivalent vibration speed is also propagated to the diaphragm portion 20, the vibration speed is equivalent to 1 m / sec in the vibration portion of the vibration mode which is the “antinode” of the diaphragm portion 20. In this vibration speed state, acoustic radiation having an ultrasonic frequency of 25 kHz is generated from the diaphragm portion 20, and the sound pressure level is 140 dB or more at a minimum.

  This sound pressure level is radiated into the space with a linear directivity from the portion of the diaphragm 20 that forms the “belt” of the “square + triangular vibration mode”. This sound radiation becomes a uniform dense wave according to the wavelength of the oscillating frequency. Sound radiation having a sound pressure level of 140 dB or more is generated with almost no attenuation even at a position 20 cm away from the diaphragm 20, and sound radiation due to non-linear sound radiation characteristics in the ultrasonic region is performed. Will be.

  FIG. 4 is a schematic diagram showing the entire system of the crack detection apparatus A. FIG. 5 is an explanatory diagram for explaining the sound radiation state of the crack detection device A and the floating state of the measurement object 25. FIG. 6 is an explanatory view schematically showing the distribution of the sound radiation state of the measurement object 25 that is levitating, that is, the movement of the “acoustic flow” when the measurement object (cell 26) is actually levitating. is there. FIG. 7 is an explanatory diagram showing sound radiation characteristics before crack detection. FIG. 8 is an explanatory diagram showing sound radiation characteristics when a crack existing in the measurement object 25 is detected. The crack detection apparatus A and the crack detection method will be described with reference to FIGS.

  As shown in FIG. 4, the crack detection apparatus A includes the ultrasonic generator 100 and the sensing unit 30 described above. The sensing unit 30 has a function of detecting spatial radiated sound generated from the diaphragm 20 and the measurement object 25. That is, the sensing unit 30 can measure and analyze a strong natural frequency of the ultrasonic band generated in the vibration plate unit 20 and a frequency component of the measurement object 25 described later. . The sensing unit 30 is installed in an axial space having a sensing distance c from a portion corresponding to the center of the diaphragm unit 20. The sensing unit 30 has a function capable of performing FFT processing on the detected sound and converting it into a function of frequency.

  By installing the sensing unit 30 in a portion corresponding to the “dense” of the dense wave due to the acoustic flow, it becomes possible to constantly receive an acoustic energy change. Since the spatially radiated sound generated from the measurement object 25 fluctuates in an arbitrary ultrasonic band, stable acoustic measurement can be achieved by installing the sensing unit 30 in a portion corresponding to “dense” of the dense wave due to the acoustic flow. It becomes possible. The sensing unit 30 is not particularly limited as long as it can perform acoustic measurement. For example, a microphone is optimally used as the sensing unit 30, but an airborne ultrasonic sensor such as a PZT piezoelectric element that can detect an ultrasonic band signal may also be used.

  As shown in FIG. 5, when the ultrasonic generator 100 is driven, the measurement object 25 is levitated in a portion between the diaphragm 20 and the sensing unit 30 where the acoustic wave causes a “sparse” density wave. be able to. When the frequency generated from the diaphragm 20 is, for example, 25 kHz, the levitation position of the measurement object 25 is determined in units of 6.8 mm of ½ wavelength. Unless the frequency generated from the diaphragm 20 fluctuates, the acoustic wave density wave does not fluctuate, so that the measurement object 25 can always be levitated in a stable state.

  Hereinafter, a case where the measurement object 25 is a solar cell for power generation (hereinafter referred to as a cell 26) used for solar power generation will be described. The cell 26 is in a very thin plate state, and currently a thin film state of around 200 μm is common. This thin cell 26 can be easily levitated in the sparse part of the acoustic flow. Therefore, the crack detection apparatus A is configured to accurately detect a crack in the material (cell 26) using the floating state of the cell 26. Needless to say, a cell having an arbitrary thickness other than the cell 26 can be levitated.

  In general, in the cell 26, an electrode necessary for power generation is formed on a base material such as ceramic by baking or the like. It is necessary to go through several work steps to reach the final cell state. During these solar cell manufacturing processes, an external force may be applied to the cell 26, so that the cell 26 may be injured with visible scratches or invisible small scratches. . Further, the cell 26 has scratches such as “missing” existing on the outer periphery thereof, microscopic scratches reaching or reaching from the inside in the thickness direction of the material of the cells 26, and further, the thickness. There may be a cavity or the like generated between the material crystals in a part of the direction.

  In order to reliably detect these various kinds of scratches existing in the cell 26, the visible scratches can be detected by a visual inspection test or a sound having a frequency characteristic in the audible range generated by lightly tapping the cell 26. There was no choice but to rely on an auditory test to distinguish changes with human ears. Therefore, it has been extremely difficult to reliably detect various scratches present in the cell 26.

  In the work process, an external force may affect the cell 26 to cause “sledge”. The amount of “sledge” is about 0.5 mm on average. When the cell 26 in this state is levitated by an “acoustic flow” caused by sound radiation in a strong ultrasonic frequency band, the acoustic flow is moved from the center of the cell 26 to the outer peripheral edge so as to follow the “sled” state of the cell 26. (See FIG. 6). Further, the strong sound pressure level has a force that causes the cell 26 to vibrate slightly. Even when the external force in the work process does not affect, when the cell 26 is levitated, the cell 26 has a “sledge”.

  Due to the minute vibration, an elastic wave is generated from the cell 26 due to a difference in elastic force between large and small “scratches” generated in the inside and / or the outer periphery. This elastic wave generates sound in a frequency band other than audible due to a difference in dimensions such as the size and shape of the scratches and a “contact sound” due to contact between the scratches. This sound is generally called AE (Acoustic Emission) and is known to have a frequency in the ultrasonic band. The “acoustic excitation” by the acoustic flow to the cell 26 due to the strong sound pressure level generates AE, and the “sledge” of the cell 26 makes it easy to vibrate = vibrate the cell 26 itself.

  Furthermore, the strong sound pressure level in the ultrasonic band has a force that penetrates the cell 26 itself, and can pass through the empty wall and the internal cavity inside the cell 26, and during this passage, friction with the air. The sound pressure level is attenuated due to the above. Therefore, by measuring in detail the attenuation of the sound pressure level at the single frequency portion of the ultrasonic transducer 12, the sound pressure level attenuation phenomenon (acoustic sound) generated by passing through the empty wall and the internal cavity inside the cell 26 is obtained. It is possible to grasp the existence of empty walls and internal cavities.

  That is, the crack detection apparatus A floats and vibrates the measurement object 25 on the upper surface of the diaphragm 20 at the “sparse” portion of the arbitrarily high density wave corresponding to the wavelength of the resonance frequency, and floats the measurement object 25. The sound flow between the vibration plate portion 20 and the diaphragm portion 20 is vibrated with periodicity, thereby generating sound radiation having a frequency variation corresponding to a crack existing in the measurement object 25 as a variation in the spatial sound field. Can do it.

  Based on FIGS. 7 and 8, the measurement result of the radiated sound measured by the sensing unit 30 will be described in more detail. FIG. 7 shows frequency characteristics when nothing is placed on the surface of the diaphragm 20. FIG. 8 shows an analysis example of the measurement result of the acoustic characteristics that the cell 26 is levitated and radiated from the cell 26. 7 and 8 are graphs showing examples of waveforms after FFT processing of radiated sound. 7 and 8, the horizontal axis represents the oscillation frequency [f], and the vertical axis represents the response (sound pressure level) [dB]. Further, Fs is an oscillation frequency (resonance frequency: K) in a resonance state when the natural frequencies radiated from the structure of the ultrasonic vibrator 12 + diaphragm portion 20 match each other, and the sound pressure is 140 dB or more on average. Has produced a level.

  The frequency characteristics can be confirmed by measuring the ultrasonic band including the resonance frequency band (with a resonance frequency K described later) of 18 kHz or more. The frequency band that can be measured depends on the sensing unit 30 used for the measurement and the circuit characteristics of the input conversion function that can input the sound pressure-voltage converted output by the sensing unit 30. In particular, when a microphone or the like is used as the sensing unit 30, it is generally a limit that can measure up to 80 kHz.

  In the state shown in FIG. 7, since nothing is on the surface of the diaphragm portion 20, only the frequency of a single ultrasonic band can be measured. A range surrounded by a broken line indicated by a solid line d shown in FIG. 7 is a bass sound level that is a minimum sound pressure level measured by the sensing unit 30, and a sound pressure level of about 30 dB is generated. In the state shown in FIG. 7, there is no sound generating material because there is no floating part in the diaphragm portion 20, and therefore no characteristic change occurs on the base line as indicated by the solid line d.

  On the other hand, in the state shown in FIG. 8, that is, in the state where some flaws exist in the levitated cell 26, the appearance phenomenon of a plurality of peak frequencies can be measured on the bass sound level line. Furthermore, depending on the state of the cell 26, a change may appear in the characteristics of the portion close to the bass sound level of the resonance frequency K. Below, the tendency of each characteristic is explained in order. Depending on the state of the cell 26, the characteristic frequency characteristic change appearing in the bass sound is not limited to one, and a plurality of changes may appear.

[Characteristic A]
This is a peak frequency component generated by the flaw state of the cell 26, and one or more peak frequency components are generated. That is, the characteristic A is generated by an arbitrary scratch existing inside the measurement object 25.
[Characteristic B]
This is a peak frequency component generated by the state of scratches generated on the outer periphery of the cell 26, and a peak frequency component close to a single is generated. That is, the characteristic B is likely to occur when there is a flaw that reaches the outer peripheral edge of the measurement object 25.

[Characteristic C]
This is a peak frequency component that occurs when a very small or very small scratch exists in the cell 26, and affects the size of the scratch and is generated in a very high frequency band.
[Characteristic D]
This is an example of frequency fluctuation that occurs when the cell 26 has a large “sledge” or when the cell 26 itself is in a weak state due to the influence of an external force, resulting in a weak state. . This characteristic D is generated at the “side” portion of the resonance frequency K.
[Characteristic E]
This is a fluctuation state of frequency characteristics due to attenuation (eg, 140 dB → 130 dB) of the maximum sound pressure level of the resonance frequency K that occurs when an air layer due to an empty wall or the like inside the cell 26 exists.

  As described above, according to the crack detection device A, since the vibration plate portion 20 that vibrates in the “square + triangular vibration mode” is provided, various fluctuations occur in the frequency characteristics depending on the measured flaw state of the cell 26. The factor can be analyzed. Also, it is possible to detect flaws by analyzing these as items for measuring fluctuations in peak value due to fluctuations in frequency characteristics and periodic fluctuations due to periodic changes in the waveform of the time axis.

  Therefore, according to the crack detection apparatus A, pressure fluctuations due to sound waves due to a dense wave having a strong sound pressure level (especially 140 dB or more) depending on the frequency of the ultrasonic band = “acoustic flow” is uniformly emitted in the air in an arbitrary area. In addition, the measurement object 25 is levitated on the part of the sparse “sparse” and the measurement object 25 levitated by using the “sledge” on the surface of the measurement object 25 is levitated + (plus) in the air By measuring the frequency fluctuation of the ultrasonic band radiated from the scratches, defects, empty walls, etc. inside the measurement object 25 by vibrating, scratches, defects, sky, etc. inside the measurement object 25, etc. It becomes possible to effectively detect problem parts such as walls.

  Moreover, according to the crack detection apparatus A, the sound radiation of the frequency fluctuation | variation according to the damage | wound which exists in the inside of the measuring object 25 etc. can be generated as a fluctuation | variation of a spatial sound field. Therefore, according to the crack detection apparatus A, there is a state in which the measurement object 25 has a problem in material rigidity such as a scratch, a defect, and a hollow wall by detecting the sound radiation fluctuation generated from the measurement object 25. Whether it exists can be measured and determined in a short time.

  Moreover, according to the crack detection apparatus A, it can be provided in any of the manufacturing line of a semiconductor substrate and the manufacturing line of some apparatus incorporating the semiconductor substrate, and the measurement object is obtained by appropriately performing the flaw detection of the measurement object 25. The yield of the objects 25 can be greatly improved.

  In the embodiment, the case where there is one sensing unit 30 has been described as an example. However, the number of sensing units 30 is not limited, and a plurality of sensing units 30 of the same type may be installed. You may make it install combining the sensing part of different structures, such as the combination of a microphone and an airborne ultrasonic sensor.

  DESCRIPTION OF SYMBOLS 10 Piezoelectric element, 11 Holding part, 12 Ultrasonic vibrator, 20 Diaphragm part, 25 Measuring object, 26 Solar cell, 30 Sensing part, 100 Ultrasonic generator, A crack detection apparatus.

Claims (7)

An ultrasonic transducer that generates ultrasonic waves in a predetermined frequency band;
A diaphragm portion that is formed of a square metal material having an arbitrary area and an arbitrary thickness, and one surface is attached to one end of the ultrasonic transducer;
Sensing means for detecting and measuring spatial radiated sound in an arbitrary ultrasonic band generated from the measurement object,
The diaphragm portion is
The natural frequency matches the natural frequency of the ultrasonic vibrator, causes a resonance phenomenon with the vibration of the ultrasonic vibrator, and the entire surface vibrates in the form of a primary vibration mode with a period that matches, An acoustic flow that is a dense wave with a single frequency in the ultrasonic band at an arbitrarily designed resonance frequency is radiated at a predetermined sound pressure level, and the object to be measured is levitated on the other surface according to the wavelength of the resonance frequency. A crack detection device characterized by vibrating. The diaphragm portion is
The acoustic flow is radiated at a sound pressure level of 140 dB or more, and the measurement object is levitated and held in a sparse part of the acoustic flow radiated from the entire surface of the diaphragm portion. Crack detection device. The sensing unit is
By detecting the frequency variation of the acoustic flow between the levitated measurement object and the diaphragm part by the warp existing on the surface of the measurement object, the presence or absence of cracks and the location of the measurement object are detected. The crack detection device according to claim 2, wherein: The primary vibration mode form of the diaphragm part,
The vibration distribution as if the left, right, top, and bottom sides were bent with the center of the vibration plate portion at the fixed portion of the ultrasonic vibrator as a base point, and the corner portion of the vibration plate portion was folded into a triangular shape. The crack detection device according to any one of claims 1 to 3, wherein a vibration distribution is selected. The diaphragm portion is
It is designed from the following formula. The crack detection device according to claim 4 characterized by things.

The sensing unit is
It is installed in the dense part of the acoustic flow radiated | emitted from the said diaphragm part. The crack detection apparatus as described in any one of Claims 1-5 characterized by the above-mentioned. Generate ultrasonic waves of a predetermined frequency band using an ultrasonic transducer,
Using a diaphragm part formed of a square metal material having an arbitrary area and an arbitrary thickness and having one surface attached to one end of the ultrasonic vibrator, the ultrasonic vibration is set to the natural frequency of the diaphragm part. The resonance frequency is made to coincide with the natural frequency of the child, causing a resonance phenomenon with the ultrasonic vibrator, and the entire surface of the diaphragm is vibrated in the form of a primary vibration mode having the same period, and ultrasonic waves are generated at an arbitrarily designed resonance frequency. An acoustic flow that is a dense wave with a single frequency in a band is radiated at a predetermined sound pressure level, and a measurement object is levitated and vibrated on the other surface of the diaphragm portion according to the wavelength of the resonance frequency,
Detect and measure spatially radiated sound in any ultrasonic band generated from the measurement object using sensing means,
The crack detection method characterized by detecting the presence or absence and the location of a crack of a measurement object by measuring the frequency fluctuation | variation of the acoustic flow between the levitated measurement object and the said diaphragm part.

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