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DESCRIPTION JP2009284043

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DESCRIPTION JP2009284043
The present invention provides an ultrasonic probe that can be realized with a simple and
inexpensive configuration, can efficiently extract a signal related to a harmonic component, and
can measure a microscopic defect with high accuracy, and a method of manufacturing the same.
An ultrasonic probe (10) comprises an ultrasonic oscillator (11) having metal films (14, 15) for
electrode formation on both sides, an acoustic lens (12), and a metal foil provided between the
ultrasonic oscillator and the acoustic lens. The ultrasonic transducer and the acoustic lens are
pressure-welded and joined to each other through a metal foil. The electrode forming metal films
14 and 15 are silver (Au) / chromium (Cr) films, and the material of the metal foil 13 is platinum
(Pt) or tungsten (W). [Selected figure] Figure 1
Ultrasonic probe and method of manufacturing the same
[0001]
The present invention relates to an ultrasonic probe and a method of manufacturing the same,
and more particularly to an ultrasonic probe having a structure suitable for detection of
microscopic defects by nonlinear ultrasonic method, and a method of manufacturing the same.
[0002]
Patent Document 1 discloses a method and an apparatus for detecting inclusions by nonlinear
ultrasonic waves.
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1
In this detection method, an ultrasonic burst wave is irradiated to the inspection object from the
ultrasonic wave generator, an ultrasonic reflection wave from the inspection object is received by
the ultrasonic wave generator, and the reflection wave is processed and reflected. The amplitude
of the wave is compared with the amplitude of the incident wave related to the ultrasonic burst
wave, and the ratio of the amplitude of the second harmonic among them is determined. Based
on the obtained ratio of the amplitude of the second harmonic to the incident wave amplitude
and the linearity existing between the input voltage to the ultrasonic oscillator, the presence or
absence of the inclusion in the inspection object is detected. Unexamined-Japanese-Patent No.
2006-284428
[0003]
The nonlinear ultrasonic method for detecting microscopic defects inside an inspection object by
using the nonlinear response characteristics of ultrasonic waves and extracting harmonics of
ultrasonic incident is a conventional linear ultrasonic method in recent years. Has attracted
attention as a method of detecting microscopic defects that can not be evaluated. However, the
nonlinear ultrasonic method utilizing the linearity between the ratio to the amplitude of the
second harmonic and the signal processing technique have the problem of being costly. In
addition, since the harmonic signal is minute, there is also a problem that the process of
discriminating from the noise greatly affects the inspection result.
[0004]
In view of the above problems, the object of the present invention can be realized with a simple
and inexpensive configuration, can efficiently extract signals relating to harmonic components,
and can accurately measure microscopic defects. It is providing a probe and its manufacturing
method.
[0005]
The ultrasonic probe and the method of manufacturing the same according to the present
invention are configured as follows in order to achieve the above-mentioned object.
[0006]
The ultrasonic probe according to the present invention comprises 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 resonator and the acoustic lens are
characterized in that they are pressure-welded and joined to each other through the metal foil.
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[0007]
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).
[0008]
In the above configuration, the acoustic lens is made of quartz.
[0009]
The method of manufacturing an ultrasonic probe according to the present invention comprises
the steps of: arranging an ultrasonic oscillator and an acoustic lens with metal foils therebetween
and opposing bonding surfaces to each other; ultrasonic oscillation Irradiating an ion beam or an
atom beam in a vacuum to each bonding surface of the element, the metal foil and the acoustic
lens, and then pressing the ultrasonic wave oscillator and the acoustic lens with the metal foil
interposed. It is a method comprising the step of bringing into close contact and the step of
pressing and joining the ultrasonic wave oscillator and the acoustic lens to each other with the
metal foil interposed therebetween.
[0010]
In the ultrasonic probe according to the present invention, in the structure in which the
ultrasonic oscillator and the acoustic lens are joined, the metal foil such as platinum (Pt) is
interposed to be pressure-welded and joined. A plurality of resonances occur with respect to the
harmonic component of H. As a result, it is possible to take a high value of the round-trip pass
rate of the high-order harmonic component and efficiently receive the harmonic component in
the water immersion measurement.
By this, it is possible to detect microscopic damage, microscopic deterioration parts and the like
inside the inspection object with high accuracy.
[0011]
In the method of manufacturing an ultrasonic probe according to the present invention, the
ultrasonic oscillator, the acoustic lens, and the metal foil are placed in a predetermined
arrangement inside the vacuum device, and the bonding surface is cleaned, pressed, and bonded.
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Thus, an ultrasonic probe capable of efficiently receiving harmonic components can be
manufactured easily and inexpensively.
[0012]
Hereinafter, preferred embodiments (examples) of the present invention will be described based
on the attached drawings.
[0013]
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 wave oscillator 11 made of a piezoelectric
element, an acoustic lens 12, and a metal foil 13 provided between the ultrasonic wave oscillator
11 and the acoustic lens 12.
The metal foil 13 is provided so as to entirely cover one end surface (the lower surface in FIG. 1)
of the acoustic lens 12.
The ultrasonic wave oscillator 11 and the acoustic lens 12 are bonded together by interposing
the metal foil 13 therebetween and pressing them against each other.
[0014]
The term “pressure contact” used in this specification, etc. cleans the surface to be joined,
applies high pressure to bring the two members into contact at the junction surface, and causes a
diffusion phenomenon at the junction surface. , Means to join the two members.
[0015]
The ultrasonic oscillator 11 has a plate-like form, and for example, PbTiO3 (lead titanate) having
an acoustic impedance of 38, PZT (Pb (Zr, Ti) O3 ceramic), or the like is used as the material.
There is.
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These materials are well known to those skilled in the art.
The center frequency of the ultrasonic oscillator 11 is, for example, 50 MHz.
[0016]
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 acoustic impedance of the metal foil 13 using platinum (Pt) is 84.6, and the longitudinal
acoustic velocity is 3960 m / s.
The metal foil 13 can also be made using tungsten (W) as another material.
[0017]
Electrodes 14 and 15 are formed on both sides of the ultrasonic oscillator 11 respectively. The
electrode 14 on one side of the ultrasonic oscillator 11 is called the upper electrode, and the
electrode 15 on the other side is called the lower electrode. The electrodes 14 and 15 are made
of a metal film for electrode formation, and the material may be any conductor, and is optional.
In the present embodiment, the upper electrode 14 is formed of, for example, an Au / Cr film.
Although the method of forming the upper electrode 14 is not particularly limited, it can be
formed, for example, by a method 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 Å. If it is less than 3000 Å, the surface roughness of
the ultrasonic oscillator 11 causes inconveniences such as the absence of the upper electrode 14,
and if it exceeds 5000 Å, there is no particular problem, but it is only uneconomical.
[0018]
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The lower electrode 15 can be formed of an Au / Cr film in the same manner as the upper
electrode 14, and the forming conditions such as thickness are the same as those of the upper
electrode 14. Since Au / Cr vapor deposited film is used as the material for forming the lower
electrode 15, the metal foil 13 provided on the bonding surface side of the acoustic lens 12 and
Pt-Au bonding at the time of bonding, so that it is chemically stable Become.
[0019]
The acoustic lens 12 is formed of quartz. Quartz is chemically very stable and excellent in
corrosion resistance. Thus, the corrosion problems that occur with metallic acoustic lenses do not
occur at all. In addition, since only the lower electrode 15 (Au / Cr film) and the metal foil 11
exist between the acoustic lens 12 and the ultrasonic oscillator 11, generation of a reflected wave
due to this film is hardly generated at the time of oscillation, which is favorable. Sound
characteristics are obtained.
[0020]
The electrode connecting lead wire 16 is connected to one end of the metal foil 13 bonded to the
end face of the acoustic lens 12. The connection of the lead wire 16 can be performed, for
example, by using a silver paste or a room temperature curing conductive resin.
[0021]
Next, with reference to FIG. 2, a method of manufacturing an ultrasonic probe according to the
present invention will be described.
[0022]
FIG. 2 is a schematic view showing the main configuration of an apparatus for manufacturing the
ultrasonic probe according to the present embodiment, and also for explaining the steps of the
manufacturing method.
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In FIG. 2, reference numeral 11 is the above-mentioned ultrasonic oscillator made of a
piezoelectric element, 12 is the above-mentioned acoustic lens made of quartz, 21a and 21b are
beam sources for generating atom beams, and 22a and 22b are pressurized It is a jig, and these
are disposed in the vacuum processing chamber 30. At an appropriate position of the vacuum
processing chamber 30, a duct 31 connected to an evacuation means (not shown) is provided.
[0023]
In the above, it is assumed that the electrodes 14 and 15 are formed on both surfaces of the
ultrasonic wave oscillator 11 as described above.
[0024]
First, the ultrasonic oscillator 11 and the acoustic lens 12 are attached to the pressure 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 surface of the ultrasonic wave oscillator 11 and the acoustic
lens 12, respectively, and the contamination layer present on these bonding surfaces (for
example, natural Remove oxides or physically adsorbed water etc.). Also in the metal foil 13, the
metal foil 13 is disposed movably up and down in the figure by a suitable support mechanism in
the space between the ultrasonic transducer 11 and the acoustic lens 12, and bonding of both
sides of the metal foil 13 is performed. The surface is irradiated with an atom beam to remove
the contamination 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 wave oscillator 11 and the acoustic lens 12 have the metal foil 13 interposed
therebetween, and are pressurized as shown by the arrows 32 using the pressure jigs 22a and
22b to bring the bonding surfaces of both members into close contact with each other. Continue
to apply pressure for a predetermined time. As a result, the ultrasonic oscillator 11 and the
acoustic lens 12 are diffused at the joint surface of the two members, and are pressure-welded in
a state in which the metal foil 13 is interposed. The pressing jig is for performing pressure
welding between the respective members, and is constituted by a hydraulic cylinder or the like.
[0025]
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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 wave absorbing material newly attached to the
pressure jig 22a is maintained in vacuum pressure at the time of pressure welding of the
ultrasonic oscillator 11, and the same pressure welding as described above is performed. The
released bonding surface of the ultrasonic wave generator 11 and the bonding surface of the
ultrasonic wave absorbing material are pressure-welded and bonded based on the conditions of
(4).
[0026]
In the present invention, an ion beam or an atom beam is used as a means for cleaning each
bonding surface such as the ultrasonic transducer 11, the acoustic lens 12, etc. The reason is that
an active surface is created in a vacuum state and It is for joining in the same chamber, holding a
state. The surface cleaning means may be plasma, an organic solvent or ultrapure water. Most
preferably, an ion beam or an atom beam is used to perform surface activation and bonding in
the same chamber. For example, a beam of argon or the like can be used as the ion beam or the
atom beam.
[0027]
Further, as the beam sources 21a and 21b, for example, an apparatus known to those skilled in
the art such as a beam gun commercially available from ATOMTECH can be used. The power of
the ion beam or atom beam required for the cleaning process of the bonding surface is not
particularly limited.
[0028]
The pressing pressure and pressing time of each member by the pressing jigs 22a and 22b may
be any size and length as long as they are necessary and sufficient to form the pressure welding
between the respective members, and is not particularly limited.
[0029]
Next, the characteristics (filter characteristics for harmonic components) of the ultrasonic probe
10 having the structure shown in FIG. 1 will be described with reference to FIGS.
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[0030]
FIG. 3 shows the calculation result of the reciprocation pass rate in the structure (PbTiO 3 / (Au /
Cr) / quartz) of the ultrasonic probe using the conventional pressure welding, and FIG. 4 shows
the pressure welding of this embodiment. The calculation result of the round-trip passage rate in
the structure (PbTiO3 / Pt foil / quartz) of an ultrasonic probe is shown.
In the structure of the conventional ultrasonic probe, 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.
[0031]
According to the structure of the conventional ultrasonic probe, if the center frequency of the
ultrasonic probe is 50 MHz (Q is calculated as 1) and the round-trip passing rate is calculated
according to the frequency, the frequency as shown in FIG. 3 The change in the round-trip
passage rate (vertical axis) relative to the change (horizontal axis) changes as it decreases gently,
and no significant change is observed. In particular, the round-trip pass rate for higher order
harmonic components is close to 0.5 as a whole, indicating a low-value round trip pass rate. In
addition, the calculation formula of a round-trip passage rate is defined by following formula (1)
and Formula (2). In addition, the “calculation formula for the round trip pass ratio” is
described, for example, in “The Japan Society of Nondestructive Testing Ultrasonics
Subcommittee (July 2000) Material No. 2163 Round Trip Rate of triple medium and its
frequency response” ing.
[0032]
[0033]
In the above equations (1) and (2), Z is an acoustic impedance, ρ is a density, C is a velocity of
sound, Z1 is an acoustic impedance of an ultrasonic oscillator, Z2 is an acoustic impedance of a
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foil, Z3 is an acoustic impedance of an acoustic lens, d Is the thickness of the foil, k2 is 2π / λ2,
and λ2 is the wavelength in the foil.
[0034]
On the other hand, according to the structure of the ultrasound probe 10 according to the
present embodiment, when the reciprocation pass ratio is similarly calculated, as shown in FIG.
The drop in value 41) is seen, and a large change has occurred.
The frequency band shown by the horizontal axis of FIG. 4 is the same as the case of the
horizontal axis shown by FIG.
According to the change characteristics shown in FIG. 4, multiple higher order resonance
phenomena can be observed with 40 MHz as the first order with reference to the dip generation
region. Thereby, it is possible to achieve an improvement in the round-trip passage rate for highorder 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, in the immersion measurement, the ultrasonic wave returning from the
microscopic defect inside the inspection object is measured. Harmonic components can be
efficiently received. It is possible to detect microscopic damage or microscopic deterioration
parts inherent to an inspection object such as a material with high accuracy.
[0035]
Next, with reference to FIG. 5, the characteristics of the ultrasound probe 10 according to
another embodiment of the present invention will be described. In FIG. 5, the calculation result of
the reciprocation pass rate in the ultrasound probe (PbTiO3 / W foil / quartz) of other
embodiment is shown. This embodiment is an example using tungsten (W) for the metal foil 13
as described above. In this case, in the case of a metal foil made of tungsten (W), the acoustic
impedance is 104, the longitudinal acoustic velocity is 5460 m / s, and the thickness is, for
example, 50 μm. Also in the change characteristic shown in FIG. 5, similar to the change
characteristic of platinum (Pt) shown in FIG. 4, a plurality of high-order resonance phenomena
are observed with 55 MHz as the primary with reference to the generation region of dip 51. can
do. Thereby, the improvement of the reciprocation pass rate can be achieved about the highorder ultrasonic wave component (harmonic component) which arises with the ultrasonic probe
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concerning this embodiment. As a result, even in the ultrasonic image inspection apparatus
including the ultrasonic probe according to this embodiment, the harmonic component of the
ultrasonic wave returned from the microscopic defect inside the inspection object in the
immersion measurement. Can be received efficiently, and microscopic damage or microscopic
deterioration parts inherent in the inspection object can be detected with high accuracy.
[0036]
In the ultrasonic probe 10 according to the present invention, as a material of the metal foil
provided between the ultrasonic oscillator and the acoustic lens, zinc (Zn), aluminum (Al),
titanium (Ti), magnesium (Mg) Even in the case of silver (Ag), zirconium (Zr), tin (Sn), gold (Au) or
the like, the same function and effect as those of the embodiment described above can be
produced.
[0037]
The configurations, shapes, sizes, and arrangement relationships described in the above
embodiments are merely schematics to the extent that the present invention can be understood
and practiced, and numerical values, compositions (materials) of each configuration, etc. Is
merely an example.
Therefore, the present invention is not limited to the described embodiments, and can be
modified in various forms without departing from the scope of the technical idea shown in the
claims.
[0038]
The ultrasound probe according to the present invention is used to detect microscopic defects of
materials and the like with high accuracy in an ultrasound imaging apparatus and the like.
[0039]
BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic vertical sectional view showing an
embodiment of an ultrasound probe according to the present invention and showing an internal
structure thereof.
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It is a typical figure for showing the important section composition of the device for
manufacturing the ultrasound probe concerning this embodiment, and also explaining the
process of the manufacturing method together. It is a frequency characteristic figure which
shows the calculation result of the round-trip passage rate in the structure (PbTiO3 / (Au / Cr) /
quartz) of the ultrasonic probe which used the conventional pressure welding. It is a frequency
characteristic figure which shows the calculation result of the round-trip passage rate in the
structure (PbTiO3 / Pt foil / quartz) of the ultrasonic probe using pressure welding according to
the present embodiment. It is a frequency characteristic figure which shows the calculation result
of the round-trip passage rate in the ultrasound probe (PbTiO3 / W foil / quartz) of other
embodiment of this invention.
Explanation of sign
[0040]
DESCRIPTION OF REFERENCE NUMERALS 10 ultrasonic probe 11 ultrasonic oscillator 12
acoustic lens 13 metal foil 14, 15 electrode 16 lead wire 21 a, 21 b beam source 22 a, 22 b
pressing jig 30 vacuum processing chamber
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