JP2009284043A - Ultrasonic probe and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic probe which has simple and inexpensive constitution, efficiently extracts a signal associated with a harmonic component, and measures a microscopic defect with high precision; and to provide a method of manufacturing the same. <P>SOLUTION: The ultrasonic probe 10 comprises: an ultrasonic oscillator 11 having metal films 14 and 15 for electrode formation on both surfaces; an acoustic lens 12; and a metal foil 13 provided between the ultrasonic oscillator and acoustic lens, both being pressed against each other with the metal foil interposed therebetween to be bonded. The metal films 14 and 15 for electrode formation are gold (Au)/chromium (Cr) films, and the material of the metal foil 13 is platinum (Pt) or tungsten (W). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ultrasonic probe and a manufacturing method thereof, and more particularly to an ultrasonic probe having a structure suitable for detecting a microscopic defect by a nonlinear ultrasonic method and a manufacturing method thereof.

Patent Document 1 discloses an inclusion detection method and apparatus using nonlinear ultrasonic waves. In this detection method, an ultrasonic burst wave is applied to the inspection object from the ultrasonic oscillator, the ultrasonic reflected wave from the inspection object is received by the ultrasonic oscillator, the reflected wave is processed, and the reflected wave is reflected. The amplitude of the wave and the incident wave amplitude related to the ultrasonic burst wave are compared, and the ratio of the amplitude of the second harmonic between them is obtained. Based on the linearity existing between the obtained ratio of the amplitude of the second harmonic to the incident wave amplitude and the input voltage to the ultrasonic oscillator, the presence or absence of inclusions in the inspection object is detected.
JP 2006-284428 A

  In recent years, the nonlinear ultrasonic method for detecting microscopic defects inside an inspection object by utilizing the nonlinear response characteristics of ultrasonic waves and extracting the harmonics of ultrasonic incidents has been a conventional linear ultrasonic method. Is attracting attention as a method for detecting microscopic defects that cannot be evaluated. However, the nonlinear ultrasonic method using the linearity between the ratio to the amplitude of the second harmonic has a problem that it is costly with respect to a signal processing technique or the like. In addition, since the harmonic signal is minute, there is a problem that the process of distinguishing from noise greatly affects the inspection result.

  An object of the present invention is to realize an ultrasonic wave that can be realized with a simple and inexpensive configuration, can efficiently extract a signal related to a harmonic component, and can accurately measure a microscopic defect. It is to provide a probe and a manufacturing method thereof.

  In order to achieve the above object, an ultrasonic probe and a manufacturing method thereof according to the present invention are configured as follows.

  An ultrasonic probe according to the present invention includes an ultrasonic oscillator having a metal film for electrode formation on both sides, an acoustic lens, and a metal foil provided between the ultrasonic oscillator and the acoustic lens. The oscillator and the acoustic lens are characterized by being pressed and joined to each other via a metal foil.

  In the above configuration, the metal film for electrode formation is a silver (Au) / chromium (Cr) film, and the material of the metal foil is platinum (Pt) or tungsten (W).

  In the above configuration, the acoustic lens is made of quartz.

  An ultrasonic probe manufacturing method according to the present invention includes an ultrasonic oscillator and an acoustic lens, a step of disposing a metal foil between them and facing each bonding surface; and ultrasonic oscillation A step of irradiating an ion beam or an atom beam in a vacuum to each joint surface of the child, the metal foil, and the acoustic lens, and then pressurizing the ultrasonic oscillator and the acoustic lens through the metal foil This is a method comprising a step of closely contacting and a step of pressure-welding the ultrasonic oscillator and the acoustic lens to each other with a metal foil interposed therebetween.

  In the ultrasonic probe according to the present invention, in the structure in which the ultrasonic oscillator and the acoustic lens are bonded, the metal foil of platinum (Pt) or the like is interposed and bonded so that the higher-order ultrasonic wave is obtained. As a result, a high-order harmonic component has a high reciprocation rate, and the harmonic component in the water immersion method measurement can be received efficiently. Thereby, it is possible to detect microscopic damage, microscopically deteriorated portions, and the like inside the inspection object with high accuracy.

  In the method of manufacturing an ultrasonic probe according to the present invention, the ultrasonic oscillator, the acoustic lens, and the metal foil are arranged in a predetermined manner inside the vacuum apparatus, and the bonding surface is purified and bonded by pressure welding. Therefore, an ultrasonic probe capable of efficiently receiving harmonic components can be manufactured easily and inexpensively.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments (examples) of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic longitudinal sectional view showing an internal structure of an ultrasonic probe according to an embodiment of the present invention. The ultrasonic probe 10 includes an ultrasonic oscillator 11 made of a piezoelectric element, an acoustic lens 12, and a metal foil 13 provided between the ultrasonic oscillator 11 and the acoustic lens 12. The metal foil 13 is provided so as to cover one end surface (the lower surface in FIG. 1) of the acoustic lens 12 entirely. The ultrasonic oscillator 11 and the acoustic lens 12 are joined by being pressed against each other with a metal foil 13 interposed therebetween.

  The term “pressure welding” used in this specification and the like means that the surfaces to be joined are cleaned and two members are brought into contact with each other by applying high pressure to cause a diffusion phenomenon on the joining surface. It means joining two members.

The ultrasonic oscillator 11 has a plate-like form and is made of, for example, PbTiO ₃ (lead titanate) having an acoustic impedance of 38, PZT (Pb (Zr, Ti) O ₃ -based ceramics), or the like. It has been. These materials are well known to those skilled in the art. The center frequency of the ultrasonic oscillator 11 is, for example, 50 MHz.

  The metal foil 13 is made of, for example, platinum (Pt) as a material. The thickness of the metal foil 13 is, for example, 50 μm. The metal foil 13 using platinum (Pt) has an acoustic impedance of 84.6 and a longitudinal wave speed of 3960 m / s. The metal foil 13 can also be made using tungsten (W) as another material.

  Electrodes 14 and 15 are formed on both surfaces of the ultrasonic oscillator 11. The electrode 14 on one surface of the ultrasonic oscillator 11 is called an upper electrode, and the electrode 15 on the other surface is called a lower electrode. The electrodes 14 and 15 are made of an electrode forming metal film, and any material may be used as long as it is a conductor. In the present embodiment, the upper electrode 14 is formed of, for example, an Au / Cr film. Although the formation method of the upper electrode 14 is not specifically limited, For example, it can form by methods, such as vapor deposition, such as sputtering or vacuum evaporation. The thickness of the upper electrode 14 is not particularly limited, but generally it is preferably in the range of 3000 to 5000 mm. If it is less than 3000 mm, the surface of the ultrasonic oscillator 11 has a roughness, which causes inconveniences such as the absence of the upper electrode 14, and if it exceeds 5000 mm, there is no particular problem, but it is only uneconomical.

  The lower electrode 15 can be formed of an Au / Cr film in the same manner as the upper electrode 14, and the formation conditions such as the thickness are the same as those of the upper electrode 14. Since an Au / Cr vapor deposition film is used as a material for forming the lower electrode 15, the metal foil 13 provided on the bonding surface side of the acoustic lens 12 and the Pt-Au bonding at the time of bonding are chemically stable. Become.

  The acoustic lens 12 is made of quartz. Quartz is very stable chemically and has excellent corrosion resistance. Therefore, the problem of corrosion that occurs in the case of a metal acoustic lens does not occur at all. Further, since only the lower electrode 15 (Au / Cr film) and the metal foil 11 are present between the acoustic lens 12 and the ultrasonic oscillator 11, there is almost no generation of a reflected wave due to this film at the time of oscillation. Sound characteristics can be obtained.

  An electrode connecting lead wire 16 is connected to one end of a metal foil 13 bonded to the end face of the acoustic lens 12. The connection of the lead wire 16 can be performed by using, for example, a silver paste or a room temperature curable conductive resin.

  Next, a method for manufacturing an ultrasonic probe according to the present invention will be described with reference to FIG.

  FIG. 2 is a schematic diagram for illustrating a configuration of a main part of an apparatus for manufacturing the ultrasonic probe according to the present embodiment and for explaining the steps of the manufacturing method. In FIG. 2, reference numeral 11 denotes the above-described ultrasonic oscillator made of a piezoelectric element, 12 denotes the above-described acoustic lens made of quartz, 21a and 21b denote beam sources that generate an atom beam, and 22a and 22b denote pressures. These are jigs, and these are arranged in the vacuum processing chamber 30. A duct 31 connected to an evacuation unit (not shown) is provided at an appropriate location in the vacuum processing chamber 30.

  In the above description, it is assumed that the electrodes 14 and 15 are formed on both surfaces of the ultrasonic oscillator 11 as described above.

  First, the ultrasonic oscillator 11 and the acoustic lens 12 are mounted on the pressurizing jigs 22 a and 22 b, respectively, and the atmosphere in the vacuum processing chamber 30 is evacuated from the duct 31. Next, an atom beam of argon is generated from the beam sources 21a and 21b, and the atom beam is irradiated to the bonding surfaces of the ultrasonic oscillator 11 and the acoustic lens 12, respectively. Remove oxides or physisorbed water). The metal foil 13 is also arranged in a space between the ultrasonic oscillator 11 and the acoustic lens 12 by an appropriate support mechanism so as to be movable up and down in the drawing, and bonded on both sides of the metal foil 13. Irradiate the surface with an atom beam to remove the contaminated layer. By this operation, the bonding surfaces of the ultrasonic oscillator 11, the acoustic lens 12, and the metal foil 13 become clean and active surfaces. Thereafter, the ultrasonic oscillator 11 and the acoustic lens 12 interpose the metal foil 13 between them, pressurize as indicated by the arrow 32 using the pressurizing jigs 22a and 22b, and bring the joint surfaces of both members into close contact with each other. Continue to pressurize for a predetermined time. Thereby, the ultrasonic oscillator 11 and the acoustic lens 12 are diffused at the joint surfaces of the two members, and are pressure-welded with the metal foil 13 interposed. The pressurizing jig is for performing press-contact joining between the members, and is configured by a hydraulic cylinder or the like.

  When the pressure welding of the ultrasonic oscillator 11 and the acoustic lens 12 is completed, the ultrasonic oscillator 11 and the pressing jig 22a are separated. Thereafter, in the same vacuum processing apparatus 30, the ultrasonic absorber newly attached to the pressurizing jig 22 a is bonded in the same manner as described above while maintaining the vacuum pressure when the ultrasonic oscillator 11 is pressed. Based on the above conditions, the released bonding surface of the ultrasonic oscillator 11 and the bonding surface of the ultrasonic absorber are pressed and bonded.

  In the present invention, an ion beam or an atom beam is used as a means for cleaning the bonding surfaces of the ultrasonic oscillator 11, the acoustic lens 12, and the like. The reason is that an active surface is formed in a vacuum state, and This is for joining in the same chamber while maintaining the state. Examples of the surface cleaning means include plasma, an organic solvent, and ultrapure water. Most preferably, an ion beam or an atom beam is used to perform surface activation and bonding in the same chamber. As the ion beam or atom beam, for example, a beam of argon or the like can be used.

  Further, as the beam sources 21a and 21b, for example, a device known to those skilled in the art such as a beam gun commercially available from Atomtech can be used. The output of the ion beam or atom beam required for the cleaning process of the joint surface is not particularly limited.

  The pressurization pressure and pressurization time of each member by the pressurizing jigs 22a and 22b are not particularly limited as long as the size and length are sufficient and sufficient to form a press-contact between the members.

  Next, the characteristics (filter characteristics with respect to the harmonic component) of the ultrasonic probe 10 having the structure shown in FIG. 1 will be described with reference to FIGS.

FIG. 3 shows the calculation result of the reciprocation rate in the structure (PbTiO ₃ / (Au / Cr) / quartz) of the ultrasonic probe using the conventional pressure welding, and FIG. 4 uses the pressure welding of this embodiment. The calculation result of the round-trip pass rate in the structure (PbTiO ₃ / Pt foil / quartz) of the existing ultrasonic probe is shown. In the conventional ultrasonic probe structure, an Au / Cr vapor deposition film or the like is formed on the entire end face of the acoustic lens 12 instead of the metal foil 13 described above. An example of a conventional ultrasonic probe is disclosed in, for example, Japanese Patent No. 3337179.

  According to the structure of the conventional ultrasonic probe, when the center frequency of the ultrasonic probe is 50 MHz (Q is calculated as 1) and the round-trip pass rate is calculated according to the frequency, the frequency is as shown in FIG. The change in the round-trip pass rate (vertical axis) with respect to the change (horizontal axis) changes as it gradually decreases, and no significant change is observed. In particular, the round-trip rate for high-order harmonic components is close to 0.5 as a whole, indicating a low-value round-trip rate. In addition, the calculation formula of the round-trip passing rate is defined by the following formulas (1) and (2). The "round-trip pass rate calculation formula" is explained in, for example, "Japan Nondestructive Inspection Association, Ultrasound Subcommittee (July 2000) Material No.2163 Round-trip pass rate of triple media and its frequency response". ing.

In the above formulas (1) and (2), Z is the acoustic impedance, ρ is the density, C is the speed of sound, Z ₁ is the acoustic impedance of the ultrasonic oscillator, Z ₂ is the acoustic impedance of the foil, and Z ₃ is the acoustic impedance of the acoustic lens. Impedance, d is the thickness of the foil, k ₂ is 2π / λ ₂ , and λ ₂ is the wavelength in the foil.

  In contrast to the above, according to the structure of the ultrasonic probe 10 according to the present embodiment, when the reciprocating pass rate is calculated in the same manner, as shown in FIG. 41), a large change has occurred. The frequency band shown on the horizontal axis in FIG. 4 is the same as that on the horizontal axis shown in FIG. According to the change characteristics shown in FIG. 4, it is possible to observe a plurality of high-order resonance phenomena with 40 MHz as the primary with the dip generation region as a reference. Thereby, it is possible to achieve an improvement in the reciprocating pass rate of higher-order ultrasonic components (harmonic components) generated in the ultrasonic probe 10. Thus, in the ultrasonic image inspection apparatus including the ultrasonic probe 10 having the structure shown in FIG. 1, the ultrasonic wave returning from the microscopic defect inside the inspection object is measured in the water immersion type measurement. Harmonic components can be received efficiently. It is possible to detect microscopic damages, microscopic deterioration portions, and the like inherent in inspection objects such as materials with high accuracy.

Next, the characteristics of the ultrasonic probe 10 according to another embodiment of the present invention will be described with reference to FIG. In FIG. 5, the calculation result of the round-trip pass rate in the ultrasonic probe (PbTiO ₃ / W foil / quartz) of another embodiment is shown. This embodiment is an example in which tungsten (W) is used for the metal foil 13 as described above. In this case, the metal foil made of tungsten (W) has an acoustic impedance of 104, a longitudinal wave velocity of 5460 m / s, and a thickness of, for example, 50 μm. Also in the change characteristic shown in FIG. 5, similarly to the change characteristic of platinum (Pt) shown in FIG. can do. Thereby, the improvement of the round-trip pass rate can be achieved for higher-order ultrasonic components (harmonic components) generated in the ultrasonic probe according to the present embodiment. Thereby, even in the ultrasonic image inspection apparatus including the ultrasonic probe according to this embodiment, the harmonic component of the ultrasonic wave returning from the microscopic defect inside the inspection object in the water immersion type measurement. Can be efficiently received, and microscopic damage, a microscopic degradation part, etc. inherent in the inspection object can be detected with high accuracy.

  In the ultrasonic probe 10 according to the present invention, the metal foil provided between the ultrasonic oscillator and the acoustic lens may be made of zinc (Zn), aluminum (Al), titanium (Ti), magnesium (Mg). ), Silver (Ag), zirconium (Zr), tin (Sn), gold (Au), and the like can produce the same effects as those of the above-described embodiment.

  The configurations, shapes, sizes, and arrangement relationships described in the above embodiments are merely schematically shown to the extent that the present invention can be understood and implemented, and the numerical values and the compositions (materials) of the respective components Is just an example. Therefore, the present invention is not limited to the described embodiments, and can be variously modified without departing from the scope of the technical idea shown in the claims.

  The ultrasonic probe according to the present invention is used for detecting microscopic defects such as materials with high accuracy in an ultrasonic image inspection apparatus or the like.

1 is a schematic longitudinal sectional view showing an internal structure of an ultrasonic probe according to an embodiment of the present invention. It is a typical figure for showing the principal part composition of the device for manufacturing the ultrasonic probe concerning this embodiment, and explaining the process of the manufacturing method collectively. It is a frequency characteristic diagram showing a calculation result of the reciprocating passage rate in the structure of the ultrasonic probe using a conventional pressure bonding _{(PbTiO 3 / (Au / Cr} ) / silica). Is a frequency characteristic diagram showing a calculation result of the reciprocating passage rate in the structure of the ultrasonic probe using a pressure bonding according to the present embodiment (PbTiO 3 / _Pt foil / quartz). It is a frequency characteristic diagram showing a calculation result of the reciprocating passage rate in the ultrasonic probe according to another embodiment of the present invention (PbTiO 3 / _W foil / quartz).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ultrasonic probe 11 Ultrasonic oscillator 12 Acoustic lens 13 Metal foil 14, 15 Electrode 16 Lead wire 21a, 21b Beam source 22a, 22b Pressure jig 30 Vacuum processing chamber

Claims (5)

An ultrasonic oscillator having a metal film for electrode formation on both sides;
An acoustic lens,
A metal foil provided between the ultrasonic oscillator and the acoustic lens,
The ultrasonic probe, wherein the ultrasonic oscillator and the acoustic lens are pressed and joined to each other through the metal foil.   The ultrasonic probe according to claim 1, wherein the metal foil is made of platinum (Pt).   2. The ultrasonic probe according to claim 1, wherein the metal foil is made of tungsten (W).   The ultrasonic probe according to claim 1, wherein the acoustic lens is made of quartz. Placing an ultrasonic oscillator and an acoustic lens with a metal foil between them and facing each joint;
Irradiating an ion beam or an atom beam in vacuum with respect to each joint surface of the ultrasonic oscillator, the metal foil, and the acoustic lens;
Then, contacting the ultrasonic oscillator and the acoustic lens while interposing the metal foil while pressing,
Pressure-bonding the ultrasonic oscillator and the acoustic lens to each other with the metal foil interposed therebetween;
A method for manufacturing an ultrasonic probe, comprising:

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