close

Вход

Забыли?

вход по аккаунту

?

DESCRIPTION JP2015036056

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2015036056
An ultrasonic probe, an ultrasonic diagnostic imaging apparatus, and a method of manufacturing
an ultrasonic probe in which the thickness of an adhesive layer for bonding a piezoelectric layer
and a reflective layer is sufficiently reduced. A thermally conductive adhesive bonds a
dematching layer (23) having an acoustic impedance higher than that of the piezoelectric layer
(24) on the surface of the piezoelectric layer opposite to the ultrasonic wave output surface. The
sum of the arithmetic mean roughness (Ra) of the bonding surfaces of the piezoelectric layer 24
and the dematching layer 23 bonded by the adhesive is 0.4 μm or less. The viscosity of the
adhesive before heat curing is set to 600 cps or less at 40 ° C. or less. [Selected figure] Figure 6
ULTRASONIC PROBE, ULTRASONIC IMAGING DEVICE, AND METHOD FOR MANUFACTURING
ULTRASONIC PROBE
[0001]
The present invention relates to an ultrasound probe, an ultrasound imaging apparatus, and a
method of manufacturing an ultrasound probe.
[0002]
As an apparatus for medical treatment, nondestructive inspection, etc., an ultrasonic diagnostic
imaging apparatus is known which obtains an image showing the inside of a subject by ultrasonic
waves.
14-04-2019
1
The ultrasonic diagnostic imaging apparatus has an ultrasonic probe provided with a
piezoelectric body that outputs an ultrasonic wave in response to an input of a drive signal. Here,
in the conventional ultrasonic probe, the ultrasonic wave output from the piezoelectric body to
the back side is reflected forward for the purpose of more efficiently transmitting the ultrasonic
wave generated from the piezoelectric body to the inspection object There is a type in which a
reflection layer (dematching layer) for the purpose is provided on the back side of the
piezoelectric body. And, in order to more efficiently reflect the ultrasonic wave by the reflective
layer, the acoustic impedance of the reflective layer is set to be larger than the acoustic
impedance of the piezoelectric body.
[0003]
The reflective layer is adhered to the back side of the piezoelectric body by an adhesive. Here, it
is desirable that the adhesive layer formed of the adhesive have a thickness as small as possible
because the ultrasonic wave output from the piezoelectric body to the reflective layer side and
the ultrasonic wave reflected by the reflective layer are attenuated. In view of this, there is known
a conventional ultrasonic probe in which the adhesive layer is made 0.01 times (one-hundredth)
or less the wavelength of ultrasonic waves (for example, Patent Document 1). .
[0004]
JP 2000-131298 A
[0005]
However, in the technique described in Patent Document 1 above, when it is intended to use
ultrasonic waves in a high frequency band, the thickness of the adhesive layer can not be made
sufficiently small, so that good acoustic characteristics can not be obtained.
For example, in the case of transmitting and receiving ultrasonic waves of high frequency such as
10 MHz, according to the description of the above-mentioned Patent Document 1, a polymeric
adhesive generally used corresponds to 0.01 times the wavelength of the ultrasonic waves.
Although the thickness of the adhesive layer is about 2.5 μm, Patent Document 1 mentioned
above does not disclose any specific means capable of realizing the thickness. Further, in the
technology described in Patent Document 1 described above, ceramics of lead titanate are
assumed as the material of the reflection layer (rear layer), but in view of the arithmetic average
14-04-2019
2
roughness of the reflection layer assumed from the particle size of the ceramics It is difficult to
make the thickness of the adhesive layer formed between the reflective layer and the
piezoelectric body 2.5 μm or less. Even if it is possible to set the thickness of the adhesive layer
to about 2.5 μm, the sensitivity drops as much as about -9 dB, and good acoustic characteristics
can not be obtained. In order to obtain good acoustic characteristics, at least the sensitivity
reduction should be suppressed to within -3 dB. However, in order to reduce the sensitivity to -3
dB or less, it is required to set the thickness of the adhesive layer to 1/250 or less of the
wavelength of the ultrasonic wave, but it is difficult with the technique described in Patent
Document 1 above.
[0006]
An object of the present invention is to provide an ultrasonic probe, an ultrasonic diagnostic
imaging apparatus, and a method of manufacturing an ultrasonic probe in which the thickness of
the adhesive layer for bonding the piezoelectric layer and the reflective layer is sufficiently
reduced. It is.
[0007]
In order to solve the above problems, according to the invention as set forth in claim 1, the
reflective layer having an acoustic impedance higher than the acoustic impedance of the
piezoelectric material is thermally cured on the surface of the piezoelectric material opposite to
the ultrasonic wave output surface. Probe obtained by bonding with a conductive adhesive, the
sum of the arithmetic average roughness (Ra) of the bonding surfaces of the piezoelectric body
and the reflective layer bonded by the adhesive is 0.4 μm or less The viscosity of the adhesive
before heat curing is 600 cps or less at 40 ° C. or less.
[0008]
The invention as set forth in claim 2 is the ultrasonic probe according to claim 1, wherein heat
curing is performed between the piezoelectric body and the reflective layer at a first temperature
lower than the curing temperature of the adhesive. A first step of releasing the excess adhesive
by pressing the piezoelectric body and the reflective layer in a direction opposite to each other
for a predetermined time in a state where the adhesive layer is formed of the adhesive, and a
curing temperature of the adhesive The piezoelectric body and the reflective layer are adhered to
each other through a second step of thermally curing the adhesive forming the adhesive layer by
heating to the second temperature and pressurizing for a predetermined time. It is characterized
by
[0009]
14-04-2019
3
The invention according to claim 3 is characterized in that, in the ultrasonic probe according to
claim 1 or 2, the adhesive has a glass transition temperature after heat curing of 50 ° C. or
higher.
[0010]
The invention according to claim 4 is characterized in that, in the ultrasonic probe according to
any one of claims 1 to 3, the reflection layer is made of a tungsten-based alloy.
[0011]
The invention according to claim 5 is characterized in that, in the ultrasonic probe according to
claim 4, the particle diameter of the tungsten-based alloy constituting the reflection layer is 1
μm or less.
[0012]
The invention according to claim 6 is the ultrasonic probe according to any one of claims 1 to 5,
wherein the thickness of the adhesive layer formed by the adhesive after thermosetting is 0.5
μm or less. It is characterized by having done.
[0013]
The invention according to claim 7 is characterized in that in the ultrasonic probe according to
any one of claims 1 to 6, the center frequency of the ultrasonic wave to be transmitted and
received is 7 MHz or more.
[0014]
The invention according to claim 8 is the ultrasonic probe according to any one of claims 1 to 7,
wherein the piezoelectric body and the reflection layer are divided by a first dividing groove at
predetermined intervals. A plurality of transducers formed in the scanning direction by being
separated from one another, each of the plurality of transducers being further divided by a
second dividing groove parallel to the first dividing groove; And a dividing element of
[0015]
The invention according to claim 9 is the ultrasound imaging apparatus according to any one of
claims 1 to 8, wherein the ultrasound imaging apparatus is an ultrasound probe according to any
one of claims 1 to 8, wherein transmission ultrasound is directed toward a subject by a drive
signal. An ultrasound probe for outputting a reception signal by outputting the reception
14-04-2019
4
ultrasonic wave from the subject by receiving the reflection ultrasound from the subject, and
displaying an ultrasound image based on the reception signal outputted by the ultrasound probe.
And an image generation unit that generates ultrasound image data.
[0016]
The invention according to claim 10 is the ultrasonic diagnostic imaging apparatus according to
claim 9, wherein the transmission ultrasonic wave is transmitted to the ultrasonic probe by
outputting the drive signal of a rectangular wave having a plurality of pulses. A transmitter is
provided to output the pulse, and the pulse width of at least one of the plurality of pulses is made
different from the pulse width of another pulse.
[0017]
The invention according to claim 11 is achieved by bonding a reflective layer having an acoustic
impedance higher than that of the piezoelectric body on a surface of the piezoelectric body
opposite to the ultrasonic wave output surface with a thermosetting adhesive. It is a
manufacturing method of the ultrasonic probe which manufactures an acoustic probe,
Comprising: The sum of the arithmetic mean roughness (Ra) of each adhesion side of the said
piezoelectric material and the reflection layer which are pasted up with the adhesive is set to 0. 4
μm or less, the adhesive has a viscosity before heat curing of 600 cps or less at 40 ° C. or less,
and at a first temperature lower than the curing temperature of the adhesive between the
piezoelectric and the reflective layer First step of releasing the excess adhesive by pressing the
piezoelectric body and the reflective layer in a direction opposite to each other for a
predetermined time in a state in which the adhesive layer is formed by the adhesive before the
thermosetting, and the adhesive To a second temperature above Warmed, characterized in that it
comprises a second step of bonding the said reflective layer and said piezoelectric body by
thermally curing the adhesive to form the adhesive layer by pressing a predetermined time.
[0018]
According to the present invention, the thickness of the adhesive layer for bonding the
piezoelectric layer and the reflective layer can be sufficiently reduced.
[0019]
It is a figure which shows the external appearance structure of an ultrasound diagnostic imaging
apparatus.
14-04-2019
5
It is a block diagram which shows schematic structure of an ultrasound diagnostic imaging
apparatus.
It is a block diagram which shows schematic structure of a transmission part.
It is a figure explaining the drive waveform of a pulse signal.
It is a figure explaining the waveform of the pulse signal to transmit.
It is sectional drawing which shows the structure of an ultrasound probe typically.
It is a figure which shows the transmission-and-reception zone characteristic of an ultrasonic
probe.
It is a graph explaining the relationship between the thickness of an adhesion layer, and the
amount of fall of the sensitivity in the frequency standardized by the central frequency of an
ultrasonic probe.
It is a flowchart explaining an example of the manufacture procedure of an ultrasonic probe.
It is a figure explaining the relationship between the total value of the arithmetic mean
roughness (Ra) of a piezoelectric layer and a dematching layer, and the thickness of an contact
bonding layer.
[0020]
Hereinafter, an ultrasound diagnostic imaging apparatus according to an embodiment of the
present invention will be described with reference to the drawings.
14-04-2019
6
However, the scope of the invention is not limited to the illustrated example.
In the following description, components having the same function and configuration are
denoted by the same reference numerals, and the description thereof is omitted.
[0021]
As shown in FIGS. 1 and 2, the ultrasonic diagnostic imaging apparatus S according to the
present embodiment includes an ultrasonic diagnostic imaging apparatus main body 1 and an
ultrasonic probe 2.
The ultrasonic probe 2 transmits an ultrasonic wave (transmission ultrasonic wave) to a subject
such as a living body (not shown) and receives a reflected wave (reflected ultrasonic wave: echo)
of the ultrasonic wave reflected by the subject. Do.
The ultrasonic diagnostic imaging apparatus main body 1 is connected to the ultrasonic probe 2
via the cable 3 and transmits a drive signal of an electric signal to the ultrasonic probe 2 to be a
subject of the ultrasonic probe 2 To transmit the transmitted ultrasonic wave to the subject, and
based on the received signal which is an electrical signal generated by the ultrasonic probe 2
according to the reflected ultrasonic wave from the inside of the subject received by the
ultrasonic probe 2 Thus, the internal state inside the subject is imaged as an ultrasound image.
[0022]
The ultrasound probe 2 includes vibrators 2a each formed of a piezoelectric element, and a
plurality of the vibrators 2a are arranged in a one-dimensional array, for example, in an
azimuthal direction (scanning direction). In the present embodiment, for example, an ultrasonic
probe 2 provided with 192 transducers 2a is used. The transducers 2a may be arranged in a twodimensional array. Further, the number of transducers 2a can be set arbitrarily. Further, in the
present embodiment, a linear scanning type electronic scan probe is adopted for the ultrasound
probe 2, but either an electronic scanning type or a mechanical scanning type may be adopted,
and a linear scanning type, Either a sector scan method or a convex scan method can be
employed. The bandwidth in the ultrasound probe 2 can be set arbitrarily.
14-04-2019
7
[0023]
For example, as shown in FIG. 2, the ultrasonic diagnostic imaging apparatus main body 1
includes an operation input unit 11, a transmission unit 12, a reception unit 13, an image
generation unit 14, a memory unit 15, and a DSC (Digital Scan Converter) And 16), a display unit
17, and a control unit 18.
[0024]
The operation input unit 11 includes, for example, various switches, buttons, a track ball, a
mouse, a keyboard, and the like for inputting a command for instructing start of diagnosis and
data such as personal information of a subject, etc. It is output to the control unit 18.
[0025]
The transmission unit 12 is a circuit that supplies a drive signal, which is an electrical signal, to
the ultrasound probe 2 via the cable 3 according to the control of the control unit 18 to cause
the ultrasound probe 2 to generate transmission ultrasound. .
More specifically, as shown in FIG. 3, the transmission unit 12 includes, for example, a clock
generation circuit 121, a pulse generation circuit 122, a pulse width setting unit 123, and a delay
circuit 124.
[0026]
The clock generation circuit 121 is a circuit that generates a clock signal that determines the
transmission timing and transmission frequency of the drive signal.
The pulse generation circuit 122 is a circuit for generating a pulse signal as a drive signal at a
predetermined cycle. For example, as shown in FIG. 4, the pulse generation circuit 122 can
generate a rectangular pulse signal by switching and outputting a ternary voltage. At this time,
although the amplitude of the pulse signal is made the same in positive polarity and negative
polarity, it is not limited to this. The configuration may be such that a pulse signal is generated
by switching between binary and quaternary voltages. The pulse width setting unit 123 sets the
pulse width of the pulse signal output from the pulse generation circuit 122. That is, the pulse
14-04-2019
8
generation circuit 122 outputs a pulse signal having a pulse waveform according to the pulse
width set by the pulse width setting unit 123. The pulse width can be varied, for example, by the
input operation by the operation input unit 11. Alternatively, the pulse width corresponding to
the identified ultrasound probe 2 may be set by identifying the ultrasound probe 2 connected to
the ultrasound imaging apparatus main body 1. In addition, there is no restriction | limiting in
particular in the shape of a drive signal, A sine wave, a cosine wave, a rectangular wave, etc. can
be selected suitably. Also, a signal obtained by combining these plural signals may be used. It is
preferable that the drive signal be a rectangular wave having a plurality of pulses from the
viewpoint of being able to be configured by a simple and small circuit. At this time, at least one
pulse of the plurality of pulses is preferably configured to have a pulse width (duty) different
from that of the other pulses. As a result, the frequency bandwidth of the drive signal is
increased, so that the frequency bandwidth of the transmitted ultrasonic waves can be further
increased, and the time resolution, that is, the distance resolution in the depth direction can be
further improved. An example of the shape of such a drive signal is shown in FIG. The drive
signal shown in FIG. 5 includes a first pulse signal, a second pulse signal different in polarity
from the first pulse signal, and a third pulse signal equal in polarity to the first pulse signal. It is a
square wave provided. The pulse width (T1) of the first pulse signal, the pulse width (T2) of the
second pulse signal, and the pulse width (T3) of the third pulse signal are set to 16 ns, 56 ns, and
104 ns, respectively. The pulse width of each pulse signal is not limited to that described above,
and can be set arbitrarily. For example, in the present embodiment, the pulse width is set to be
gradually larger, but the pulse width may be set to be gradually smaller.
Thus, the frequency bandwidth of the drive signal can be further increased by making all the
pulse widths of the first to third pulses different. The pulse widths of all pulse signals among the
plurality of pulse signals may be set to be the same.
[0027]
The delay circuit 124 sets a delay time of the drive signal transmission timing for each individual
path corresponding to each transducer, delays transmission of the drive signal by the set delay
time, and forms a transmission beam constituted by transmission ultrasonic waves. Is a circuit for
performing focusing.
[0028]
The transmission unit 12 configured as described above sequentially switches the plurality of
transducers 2a that supply the drive signal while shifting the predetermined number for each
transmission and reception of the ultrasonic waves under the control of the control unit 18, and
the plurality of output selected The scanning is performed by supplying a drive signal to the
vibrator 2a of
14-04-2019
9
[0029]
As shown in FIG. 2, the receiving unit 13 is a circuit that receives a reception signal of an
electrical signal from the ultrasound probe 2 via the cable 3 according to the control of the
control unit 18.
The receiving unit 13 includes, for example, an amplifier, an A / D conversion circuit, and a
phasing addition circuit.
The amplifier is a circuit for amplifying the reception signal at a predetermined amplification
factor set in advance for each individual path corresponding to each vibrator 2a. The A / D
conversion circuit is a circuit for analog-digital conversion (A / D conversion) of the amplified
reception signal. The phasing addition circuit gives a delay time to the A / D converted received
signal for each individual path corresponding to each vibrator 2a, adjusts the time phase, adds
them (phasing addition), and generates a sound. It is a circuit for generating line data.
[0030]
The image generation unit 14 performs envelope detection processing, logarithmic amplification,
and the like on the sound ray data from the reception unit 13, performs gain adjustment and the
like, and performs luminance conversion to generate B-mode image data. That is, B-mode image
data represents the intensity of the received signal by luminance. The B mode image data
generated by the image generation unit 14 is transmitted to the memory unit 15.
[0031]
The memory unit 15 is formed of, for example, a semiconductor memory such as a dynamic
random access memory (DRAM), and stores B-mode image data transmitted from the image
generation unit 14 in frame units. That is, the memory unit 15 can be stored as ultrasound
diagnostic image data configured in frame units. The ultrasound diagnostic image data stored in
the memory unit 15 is read according to the control of the control unit 18 and transmitted to the
DSC 16.
14-04-2019
10
[0032]
The DSC 16 converts the ultrasound diagnostic image data received from the memory unit 15
into an image signal according to a television signal scanning method, and outputs the image
signal to the display unit 17.
[0033]
The display unit 17 is applicable to a display device such as an LCD (Liquid Crystal Display), a
CRT (Cathode-Ray Tube) display, an organic EL (Electronic Luminescence) display, an inorganic
EL display, and a plasma display.
The display unit 17 displays an ultrasound diagnostic image on the display screen in accordance
with the image signal output from the DSC 16. Note that, instead of the display device, a printing
device such as a printer may be applied.
[0034]
The control unit 18 includes, for example, a central processing unit (CPU), a read only memory
(ROM), and a random access memory (RAM), reads various processing programs such as a
system program stored in the ROM, and In accordance with the developed program, the
operation of each part of the ultrasonic diagnostic imaging apparatus S is centrally controlled.
The ROM is constituted by a nonvolatile memory such as a semiconductor, and stores a system
program corresponding to the ultrasound diagnostic imaging apparatus S, various processing
programs executable on the system program, various data, and the like. These programs are
stored in the form of computer readable program code, and the CPU sequentially executes
operations according to the program code. The RAM forms a work area for temporarily storing
various programs executed by the CPU and data related to these programs.
[0035]
Next, the structure of the ultrasound probe 2 will be described.
[0036]
14-04-2019
11
As shown in FIG. 6, for example, the ultrasonic probe 2 has a backing (back) layer 22, a
dematching (reflection) layer 23, a piezoelectric layer 24, and an acoustic matching layer 25
stacked from the bottom in a front view of the figure. Is configured.
An acoustic lens may be stacked above the acoustic matching layer 25 as necessary.
[0037]
The backing layer 22 is an ultrasonic absorber that supports the dematching layer 23 and can
absorb unnecessary ultrasonic waves. That is, the backing layer 22 is provided on the opposite
side of the piezoelectric layer 24 to the direction in which ultrasonic waves are transmitted to
and received from the subject, and is generated from the opposite side of the direction of the
subject to the piezoelectric layer 24 and reaches the backing layer 22 Absorbs ultrasound. In the
present embodiment, the backing layer 22 may not be provided.
[0038]
As a backing material which constitutes backing layer 22, vinyl chloride, polyvinyl butyral (PVB),
ABS resin, polyurethane (PUR), polyvinyl alcohol (PVAL), polyethylene (PE), polypropylene (PP),
polyacetal (POM), polyethylene Thermoplastic resins such as terephthalate (PETP), fluorocarbon
resin (PTFE), polyethylene glycol, polyethylene terephthalate-polyethylene glycol copolymer,
natural rubber, ferrite rubber, epoxy resin, silicone resin powder such as tungsten oxide, titanium
oxide, ferrite A composite material which has been pressed and molded, and further, the
composite material is pulverized and then mixed with the above-described thermoplastic resin,
epoxy resin or the like to be cured can be used. In order to adjust the acoustic impedance, an
inorganic material such as macor glass or a porous material having an air gap can also be used.
[0039]
A preferable backing material is a rubber composite material and / or an epoxy resin composite
material, and the shape thereof is appropriately selected according to the shape of the
piezoelectric layer 24 and the ultrasonic probe 2 including the same. be able to.
14-04-2019
12
[0040]
The dematching layer 23 is formed of a material whose acoustic impedance is larger than that of
the piezoelectric layer 24, and reflects ultrasonic waves output to the side opposite to the
direction of the object with respect to the piezoelectric layer 24.
As a material to be applied to the dematching layer 23, any material such as tungsten or
tantalum may be applicable as long as the material has a large difference in acoustic impedance
between the piezoelectric layer 24 and the dematching layer 23. It is suitable. Also, it may be a
mixture of tungsten carbide and another material such as cobalt. That is, in the present
embodiment, it is preferable to apply a tungsten-based alloy, and more preferably, the particle
size is 1 μm or less. In this way, the arithmetic average roughness (Ra) of the tungsten-based
alloy can be 0.2 μm or less. In the present embodiment, by providing the dematching layer 23,
the sensitivity to the transmission and reception of ultrasonic waves in the piezoelectric layer 24
can be further improved.
[0041]
The piezoelectric layer 24 is formed of a plurality of layers or a single layer of piezoelectric
material. As materials of the piezoelectric body, conventionally used quartz, piezoelectric
ceramics PZT, PZLT, thin films such as piezoelectric single crystals PZN-PT, PMN-PT, LiNbO3,
LiTaO3, KNbO3, ZnO, AlN, etc. In addition to inorganic piezoelectric materials, polyvinylidene
fluoride and polyvinylidene fluoride copolymers, polyvinylidene cyanide and vinylidene cyanide
copolymers, odd nylon such as nylon 9 and nylon 11, aromatic nylon, alicyclic nylon, poly
Examples thereof include lactic acid, polyhydroxycarboxylic acids such as polyhydroxybutyrate,
cellulose derivatives, and organic piezoelectric materials such as polyurea. Furthermore,
composite materials in which an inorganic piezoelectric material and an organic piezoelectric
material, and an inorganic piezoelectric material and an organic polymer material are used in
combination are also included.
[0042]
The piezoelectric material mentioned above can use a commercially available thing as an
inorganic piezoelectric material, For example, C-6, C-6H, C-62, C-63, C-63, C-64, C made from
Fuji ceramic company -601, C-7, C-8, C-82, C-83H, C-9, C-91, C-91H, C-92H, or L-1A, L-6A, L
14-04-2019
13
manufactured by Tayca Corporation -201F, L-11, L-9, L-155N, L-145N etc. are mentioned.
Further, as an organic piezoelectric material, a PVDF film manufactured by Tokyo Sensor, a poly
(vinylidene fluoride-co-trifluoroethylene) film manufactured by Kureha, a poly (vinylidene
fluoride-co-hexafluoro) manufactured by Aldrich as a reagent Propylene) and the like.
[0043]
As a method of forming a piezoelectric layer made of an organic piezoelectric material, a method
of forming a film by coating or a method of forming a film by vapor deposition (vapor deposition
polymerization) is preferable. Examples of the coating method include spin coating, solvent
casting, melt casting, melt pressing, roll coating, flow coating, printing, dip coating, and bar
coating. In addition, as a vapor deposition (vapor deposition polymerization) method, a film can
be obtained by evaporating a monomer from one or more evaporation sources at a degree of
vacuum of about several hundreds Pa or less, and depositing and reacting on a substrate. .
Temperature control of the substrate is appropriately performed as needed.
[0044]
In order to form the electrode layer on the organic piezoelectric film formed as described above,
first, a base metal such as titanium (Ti) or chromium (Cr) is formed to a thickness of 0.02 to 1.0
μm by sputtering. And then forming a metal material consisting mainly of a metal element or a
metal alloy thereof with a part of the insulating material, if necessary, to a thickness of 1 to 10
μm by a suitable method such as sputtering. It is done by doing. Thereafter, polarization
processing is performed. As the metal material, gold (Au), platinum (Pt), silver (Ag), palladium
(Pd), copper (Cu), nickel (Ni), tin (Sn) or the like is used. Electrode formation can also be
performed by apply | coating the conductive paste which mixed the metal powder of fine powder
and low melting glass with screen printing, the dipping method, the thermal-spraying method etc.
besides said sputtering method.
[0045]
In the present embodiment, the piezoelectric layer 24 resonates in the nλ / 4 (n is an odd
number) resonance mode and outputs transmission ultrasonic waves when the transmission
signal is given from the transmission unit 12 according to the configuration described above. The
present embodiment is particularly effective when applied to the ultrasound probe 2 whose
14-04-2019
14
output center frequency is 7 MHz or more, but is not limited thereto.
[0046]
The piezoelectric layer 24 and the dematching layer 23 are stacked via the adhesive layer 26. As
an adhesive for forming the adhesive layer 26, a thermosetting adhesive such as an epoxy-based
adhesive can be used. In the present embodiment, in order to set the thickness of the adhesive
layer 26 to 0.5 μm or less, a low viscosity adhesive having a viscosity before heat curing of 600
cps or less at 40 ° C. or less is used. At this time, it is preferable that the glass transition
temperature (Tg) after thermosetting is 50 ° C. or more. When a thermosetting adhesive such as
a high viscosity epoxy resin is used as in the prior art, the thickness of the adhesive layer 26
between the piezoelectric layer 24 and the dematching layer 23 becomes large, and the
piezoelectric layer 24 and the dematching layer 23 As a result, it becomes difficult to ensure the
continuity of the electric field, and unnecessary reflection in the adhesive layer 26 is caused, and
the acoustic characteristics of the ultrasonic probe 2 are degraded. In the present embodiment,
by using the above-described low viscosity adhesive, the excess adhesive can be easily released in
the bonding step, and the bonding layer 26 can be easily thinned. In particular, in the use in the
high frequency band, it is useful because it is necessary to make the thickness of the adhesive
layer thinner than conventionally expected.
[0047]
Here, the reason why the thickness of the adhesive layer 26 is preferably 0.5 μm or less will be
described.
[0048]
In the conventional ultrasonic probe, in order to efficiently generate an ultrasonic wave of a
desired transmission / reception frequency, a vibration mode of λ / 2 resonance has been used
in the piezoelectric layer.
In this case, since the acoustic power is also distributed to the backing layer, the efficiency is not
good in terms of sensitivity. On the other hand, by providing a dematching layer having a larger
acoustic impedance than the piezoelectric layer on the back side of the piezoelectric layer, the λ
/ 4 resonance vibration mode can be used, and the acoustic loss rotating to the back side of the
piezoelectric layer can be reduced. It can be made smaller. At this time, the influence of the
14-04-2019
15
adhesive layer which bonds the piezoelectric layer and the dematching layer can not be ignored.
[0049]
FIG. 7 shows the relationship between the thickness of the adhesive layer and the transmission /
reception sensitivity. The line indicated by A in FIG. 7 indicates the transmission / reception band
characteristics of the ultrasonic probe when the thickness of the adhesive layer is 0 μm, and the
line indicated by B indicates that the thickness when the adhesive layer is 0.2 μm. The line
indicated by C indicates the transmission / reception band characteristic of the acoustic wave
probe, and the line indicated by C indicates the transmission / reception band characteristic of
the ultrasonic probe when the thickness of the adhesive layer is 0.4 μm, and the line indicated
by D indicates the adhesion layer The transmission and reception band characteristics of the
ultrasonic probe when the thickness is 0.6 μm are shown, and the line shown by E is the
transmission and reception band characteristics of the ultrasonic probe when the thickness of the
adhesive layer is 0.8 μm. The lines indicated by and F indicate the transmission / reception band
characteristics of the ultrasonic probe when the thickness of the adhesive layer is 1 μm, and the
lines indicated by G indicate the ultrasonic probe when the thickness of the adhesive layer is 2
μm And the line indicated by H represents the transmission and reception band characteristics
of the ultrasonic probe when the thickness of the adhesive layer is 3 .mu.m. The line indicated by
I indicates the transmission / reception band characteristics of the ultrasonic probe when the
thickness of the adhesive layer is 4 μm, and the line indicated by J indicates the ultrasonic probe
when the thickness of the adhesive layer is 5 μm The transmission and reception band
characteristics of the child are shown.
[0050]
Also, FIG. 8 shows the relationship between the thickness of the adhesive layer and the amount
of decrease in sensitivity at a frequency normalized to the center frequency of the ultrasonic
probe. Here, the frequency normalized by the center frequency of the ultrasound probe is, for
example, a value obtained by dividing a certain frequency by the center frequency in the
transmission / reception band characteristics of the ultrasound probe whose center frequency is
10 MHz. Indicates The line shown by A in FIG. 8 shows the case where the frequency value
normalized to the center frequency of the ultrasound probe is about 0.700, and the line shown
by B in FIG. 8 is the center of the ultrasound probe The case where the frequency value
normalized by the frequency is about 0.804 is shown, and the line shown by C in FIG. 8 is the
case where the frequency value normalized by the center frequency of the ultrasonic probe is
about 0.895. The line indicated by D in FIG. 8 indicates the case where the frequency value
14-04-2019
16
normalized to the center frequency of the ultrasonic probe is about 0.998, and the line indicated
by E in FIG. 8 indicates the ultrasonic probe. The frequency value normalized to the center
frequency of is approximately 1.102, and the line indicated by F in FIG. 8 has a frequency value
normalized to the center frequency of the ultrasonic probe of approximately 1.206. The line
indicated by G in FIG. 8 indicates the case where the frequency value normalized to the center
frequency of the ultrasonic probe is about 1.300. The line indicated by H in FIG. 8 indicates the
case where the frequency value normalized to the center frequency of the ultrasonic probe is
about 1.400, and the line indicated by I in FIG. 8 is the ultrasonic probe. The case is shown in
which the frequency value normalized at the center frequency of is approximately 1.465.
[0051]
As shown in FIGS. 7 and 8, it can be seen that as the thickness of the adhesive layer increases, the
band on the high frequency side is chipped and the transmission and reception sensitivity also
decreases.
[0052]
Therefore, although it is impossible in practice to make the thickness of the adhesive layer 0, a
sensitivity close to the ideal can be obtained if the thickness is suppressed within -5 dB from the
ideal sensitivity state.
For that purpose, the thickness of the adhesive layer is preferably 0.5 μm or less.
[0053]
An FPC (Flexible Printed Circuits) 27 is sandwiched between the backing layer 22 and the
dematching layer 23, and the FPC 27 applies a transmission signal from the transmitter 12 to the
piezoelectric layer 24. Further, the reception signal generated by the piezoelectric layer 24 is
given to the receiving unit 13 by the FPC 27.
[0054]
The acoustic matching layer 25 matches the acoustic impedance between the piezoelectric layer
14-04-2019
17
24 and the subject to suppress reflection at the interface. The acoustic matching layer 25 is
disposed on the object side of the piezoelectric layer 24 in the direction in which transmission
and reception of ultrasonic waves are performed. The acoustic matching layer 25 has an acoustic
impedance substantially intermediate between the piezoelectric layer 24 and the subject.
[0055]
Materials used for the acoustic matching layer 25 include aluminum, aluminum alloy (for
example, AL-Mg alloy), magnesium alloy, macor glass, glass, fused quartz, copper graphite, PE
(polyethylene), PP (polypropylene), PC (polycarbonate) ), ABC resin, ABS resin, AAS resin, AES
resin, nylon (PA6, PA6-6), PPO (polyphenylene oxide), PPS (polyphenylene sulfide: may be
contained in glass fiber), PPE (polyphenylene ether), PEEK (poly Ether ether ketone), PAI
(polyamide imide), PETP (polyethylene terephthalate), epoxy resin, urethane resin and the like
can be used. It is preferable to use a thermosetting resin such as epoxy resin as a filler, which is
formed by adding zinc flower, titanium oxide, silica or alumina, bengara, ferrite, tungsten oxide,
ytterbium oxide, barium sulfate, tungsten, molybdenum, etc. Applicable
[0056]
The acoustic matching layer 25 may be a single layer or a plurality of layers, but is preferably
two or more layers, more preferably four or more layers. The layer thickness of the acoustic
matching layer 25 is preferably determined to be λ / 4, where λ is the wavelength of ultrasonic
waves. The thickness of such an acoustic matching layer depends on the center frequency, but
generally, a thickness in the range of about 20 to 500 μm is used. The acoustic matching layer
25 is formed by multi-layer coating in the thickness direction, and the acoustic impedance is
matched by weighting the acoustic impedance in the thickness direction by making each material
configuration different in each layer. The weighting direction of the acoustic impedance in the
acoustic matching layer 25 is not limited to the thickness direction, but may be horizontal.
[0057]
Next, an example of the manufacturing procedure of the ultrasound probe 2 according to the
present embodiment will be described with reference to FIG.
[0058]
14-04-2019
18
First, the backing layer 22 and the FPC 27 are laminated on the base block and adhered (step
S10).
The laminate produced in this manner is referred to as a laminate A.
[0059]
Next, the acoustic matching layer 25 is manufactured (step S20). Specifically, acoustic matching
materials having different acoustic impedances are manufactured using the above-described
materials. Then, low viscosity epoxy adhesives are applied and laminated on the bonding surfaces
of these acoustic matching materials, and pressure curing is performed using a dedicated
pressing jig to produce the acoustic matching layer 25. The acoustic matching layer 25 may be
made of a single layer.
[0060]
Next, the acoustic matching layer 25, the piezoelectric layer 24, and the dematching layer 23 are
stacked and bonded (step S30). Specifically, first, the piezoelectric layer 24 is polished until the
arithmetic mean roughness (Ra) becomes 0.25 μm or less, preferably 0.1 μm or less, and then
an electrode is formed on the surface. . Similarly, the dematching layer 23 is polished to have an
arithmetic average roughness (Ra) of 0.1 μm or less, and then an electrode is formed on the
surface. It is preferable that the arithmetic mean roughness (Ra) of the dematching layer 23 be
smaller than the arithmetic mean roughness (Ra) of the piezoelectric layer 24. Thereafter, the low
viscosity epoxy adhesive described above is applied to the bonding surfaces of the acoustic
matching layer 25, the piezoelectric layer 24, and the dematching layer 23, respectively. Then,
these are set and superimposed on a dedicated pressing jig heated to a predetermined
temperature (for example, 50 ° C.). Then, the weight is gradually applied with a predetermined
interval until reaching a predetermined weight (for example, 30 kg weight), and the heating of
the jig is stopped when the predetermined weight is reached, and the temperature is higher than
the curing temperature of the adhesive. Continue to apply pressure for a predetermined time
(e.g., 10 hours) while returning to a low first temperature (e.g., normal temperature) (i.e.,
continue applying pressure in the direction in which the piezoelectric layer 24 and the
dematching layer 23 face each other) Let go (the first step). Thereafter, the pressing jig is heated
to a second temperature (e.g., 50.degree. C.) which is equal to or higher than the curing
temperature of the adhesive, and pressure cured for a predetermined time (e.g., 8 hours). An
14-04-2019
19
adhesive layer 26 is formed between it and the matching layer 23 (second step). Thereby, the
acoustic matching layer 25, the piezoelectric layer 24, and the dematching layer 23 can be
bonded. By performing adhesion through such a process, the adhesion layer 26 can be thinned
while maintaining good adhesion between the piezoelectric layer 24 and the dematching layer
23. The laminate produced in this manner is referred to as a laminate B.
[0061]
Subsequently, isolation of the dematching layer 23 is performed (step S40). Specifically,
insulating grooves are formed along the longitudinal direction in the vicinity of both ends of the
short axis on the back surface side of the dematching layer 23 to form a signal electrode and a
ground electrode. The insulating groove is inserted to a depth reaching the piezoelectric layer 24.
Incidentally, after an insulating groove is formed in advance in the piezoelectric layer 24 and the
piezoelectric layer 24 and the dematching layer 23 are bonded, the groove is formed from the
back side of the dematching layer 23 so as to communicate with the insulating groove. You may
[0062]
Next, the laminate B is bonded to the laminate A produced as described above (step S50).
[0063]
Next, the laminated body manufactured in this manner is subjected to dicing for complete
division from the acoustic matching layer 25 to the dematching layer 23 at predetermined
intervals (for example, 0.2 mm) to form an element. 2a is manufactured (step S60).
At this time, one or more dividing grooves may be formed by performing sub-dicing on the
divided vibrators 2a. The sub dicing is performed, for example, by dicing from the acoustic
matching layer 25 to the dematching layer 23. The dicing may be performed halfway to the
piezoelectric layer 24 without dicing up to the dematching layer 23.
[0064]
Thereafter, a protective layer of polyparaxylylene is formed on the surface of the vibrator 2a
(step S70).
14-04-2019
20
[0065]
Finally, an acoustic lens is stacked and adhered in the transmission / reception direction of the
ultrasonic wave to the subject of the protective layer (step S80).
[0066]
Hereinafter, the present invention will be described in more detail by way of examples, but of
course the present invention is not limited to these examples.
[0067]
Example 1 First, cobalt-doped tungsten carbide having an acoustic impedance of 100 MRayls is
lapped to an arithmetic mean roughness (Ra) of 0.075 μm to a thickness of 80 μm, which is 4.6
mm × It cut out to the magnitude | size of 42.5 mm, and made this 1st to-be-adhered body.
The polishing method is not limited to that described above, and various methods such as
polishing mirror polishing, buffing, tape polishing, barrel processing, jet processing, ultrasonic
processing, electrolytic composite polishing, rotary grinding processing, honing processing, etc.
may be used. It is also possible to carry out by combining these.
Subsequently, a ground layer of a 0.05 μm thick Cr layer is sputtered onto the tungsten carbide
cut out, and an Au layer of 0.1 μm thick is further sputtered to form an electrode. It was a
dematching layer.
[0068]
Next, the PZT-based piezoelectric body is subjected to the above-mentioned polishing treatment
so that the arithmetic average roughness (Ra) is 0.075 μm, to prepare a piezoelectric body
having a thickness of 80 μm, which is 4.6 mm × It cut out to the size of 42.5 mm, and made
this 2nd to-be-adhered body.
Subsequently, a Cr layer of 0.05 μm in thickness was subjected to a base treatment by
sputtering on this piezoelectric body, and further, an Au layer of 0.1 μm in thickness was
14-04-2019
21
applied by sputtering to form an electrode. Then, insulating grooves were formed along the
longitudinal direction in the vicinity of both short axis ends on the back side so that the effective
opening in the short axis direction was 4.0 mm, thereby forming a signal electrode and a ground
electrode, to produce a piezoelectric layer. The sum of the arithmetic mean roughness (Ra) of the
first adherend and the arithmetic mean roughness (Ra) of the second adherend was 0.150 μm.
[0069]
Next, six acoustic matching materials were laminated to produce an acoustic matching layer. The
acoustic matching materials of the respective layers were produced by kneading and curing the
epoxy resin and the ferrite or the fine powder of the silicone resin so as to satisfy the following
conditions. That is, the acoustic matching material of the uppermost layer, which is the
outermost layer on the acoustic radiation side, has an acoustic impedance of 1.5 MRayls and a
thickness of 20 μm, and the acoustic matching material of the second layer has an acoustic
impedance of 2.0 MRayls and a thickness of 30 μm, The third layer acoustic matching material
has an acoustic impedance of 3.0 MRayls and a thickness of 30 μm, and the fourth layer
acoustic matching material has an acoustic impedance of 6.0 MRayls and a thickness of 40 μm.
The acoustic impedance was 9.0 MRayls and the thickness was 50 μm, and the acoustic
matching material in the lowermost layer was the acoustic impedance 14.0 MRays and the
thickness 60 μm. Then, after performing a primer treatment for each acoustic matching
material, a low viscosity epoxy adhesive having a viscosity of 600 cps or less under heating at 50
° C. is applied to the bonding surface of each acoustic matching material using a spatula. Then,
it was set in a dedicated pressing jig heated to 50 ° C., and the acoustic matching materials of
the respective layers prepared as described above were laminated and bonded in the abovementioned order. Subsequently, the laminated acoustic matching material is first pressurized
with the weight of the jig and then gradually weighted at a predetermined interval until it
reaches 30 kg, and when it reaches 30 kg, the jig is heated. It stopped and it kept pressurizing
for 10 hours, returning to normal temperature, and was made to escape an excess adhesive.
Thereafter, the jig was heated again to 50 ° C., and after being pressure-cured for 8 hours, this
was cut into a size of 4.6 mm × 42.5 mm to make an acoustic matching layer.
[0070]
Next, an epoxy-based backing material having an acoustic impedance of 3 M Rayls prepared by
adding tungsten powder having an average particle diameter of 8 μm to an epoxy resin is
prepared, and cut into a size of 4.6 mm × 42.5 mm × 3 mm as a backing layer. Then, an epoxybased adhesive is applied to the backing layer, the backing layer and the patterned FPC are
14-04-2019
22
laminated on the fixing plate (base block), and heating is performed at 50 ° C. for 4 hours with a
dedicated pressing jig. By pressure curing, a laminate of the fixing plate, the backing layer and
the FPC was produced.
[0071]
Next, a primer treatment is applied to each of the acoustic matching layer, the piezoelectric layer
and the dematching layer prepared as described above, and the low viscosity epoxy adhesive
having a viscosity of 400 cps under heating at 50 ° C. is acoustically matched. It apply | coated
using the spatula on each joining surface of a layer, a piezoelectric layer, and a dematching layer,
respectively, these were sequentially set and superposed | superposed in the exclusive pressure
jig of the state heated at 50 degreeC. The acoustic matching layer was superimposed such that an
acoustic matching material having high acoustic impedance was in contact with the piezoelectric
layer. Then, after the excess adhesive is released by applying pressure by the weight of the jig,
load is gradually applied with a predetermined interval until reaching 30 kg, and heating of the
jig is stopped when reaching 30 kg, The pressure was continued for 10 hours while returning to
normal temperature to further release the excess adhesive. Thereafter, the jig was heated again
to 50 ° C. and pressure cured for 8 hours. Then, the dematching layer was grooved by dicing in
a width of 40 μm and a depth of 90 μm along the longitudinal direction from the back side so
as to communicate with the insulating groove formed in the piezoelectric layer (isolation).
[0072]
Thereafter, the laminate of the acoustic matching layer, the piezoelectric layer, and the
dematching layer manufactured as described above was laminated and adhered to the laminate
of the fixing plate, the FPC, and the backing layer. Thereby, the signal electrode and the ground
electrode of the piezoelectric layer are respectively connected to the signal electrode surface and
the ground electrode surface formed on the FPC using the dematching layer as the wiring while
maintaining the insulation state. Then, using a blade having a thickness of 20 μm, the laminated
body manufactured in this manner is subjected to dicing to completely divide the acoustic
matching layer to the dematching layer at intervals of 0.2 mm in the longitudinal direction
(azimuth direction). The first dividing groove is formed to form an element, and further, the
divided element is subjected to sub-dicing in which the acoustic matching layer and the
piezoelectric layer are completely divided at intervals of about 67 μm parallel to the first
dividing groove by the above-mentioned blade To form a second split groove to produce a
vibrator provided with a plurality of split elements.
14-04-2019
23
[0073]
Thereafter, a protective layer of about 3 μm of polyparaxylylene was formed on the surface of
the vibrator, and an acoustic lens was laminated on the acoustic emission surface of this
protective layer and adhered to produce a vibrating portion.
[0074]
Next, after connecting a connector to the FPC, the vibration unit manufactured as described
above was housed in a case to manufacture an ultrasonic probe of Example 1.
[0075]
(Example 2) By the above-described polishing process, the arithmetic average roughness (Ra) of
the first adherend is set to 0.075 μm, and the arithmetic average roughness (Ra) of the second
adherend is set to 0.230 μm. The ultrasonic probe of Example 2 was produced in the same
manner as Example 1 except for the above.
At this time, the sum of the arithmetic average roughness (Ra) of the first adherend and the
arithmetic average roughness (Ra) of the second adherend was 0.305 μm.
[0076]
(Example 3) By the above-mentioned polishing treatment, the arithmetic average roughness (Ra)
of the first adherend is 0.130 μm, and the arithmetic average roughness (Ra) of the second
adherend is 0.230 μm. The ultrasonic probe of Example 3 was produced in the same manner as
in Example 1 except for the above.
At this time, the sum of the arithmetic mean roughness (Ra) of the first adherend and the
arithmetic mean roughness (Ra) of the second adherend was 0.360 μm.
[0077]
14-04-2019
24
(Example 4) By the above-described polishing treatment, the arithmetic average roughness (Ra)
of the first adherend is 0.140 μm, and the arithmetic average roughness (Ra) of the second
adherend is 0.230 μm. The ultrasonic probe of Example 4 was produced in the same manner as
in Example 1 except for the above. At this time, the sum of the arithmetic mean roughness (Ra) of
the first adherend and the arithmetic mean roughness (Ra) of the second adherend was 0.370
μm.
[0078]
Comparative Example 1 By the above-described polishing process, the arithmetic average
roughness (Ra) of the first adherend is 0.270 μm, and the arithmetic average roughness (Ra) of
the second adherend is 0.260 μm. An ultrasonic probe of Comparative Example 1 was produced
in the same manner as in Example 1 except for the above. At this time, the sum of the arithmetic
mean roughness (Ra) of the first adherend and the arithmetic mean roughness (Ra) of the second
adherend was 0.530 μm.
[0079]
Comparative Example 2 By the above-described polishing process, the arithmetic average
roughness (Ra) of the first adherend is 0.233 μm, and the arithmetic average roughness (Ra) of
the second adherend is 0.630 μm. The ultrasonic probe of Comparative Example 2 was
produced in the same manner as in Example 1 except for the above. At this time, the sum of the
arithmetic mean roughness (Ra) of the first adherend and the arithmetic mean roughness (Ra) of
the second adherend was 0.863 μm.
[0080]
Comparative Example 3 A high viscosity epoxy adhesive having a viscosity of 13,000 cps under
heating at 50 ° C. is used as an adhesive used when bonding the acoustic matching layer, the
piezoelectric layer, and the dematching layer, 50 The acoustic matching layer, the piezoelectric
layer and the dematching layer were sequentially set and superposed on a dedicated pressing jig
in a state of being heated to ° C. Then, after the excess adhesive was released by pressing with
the weight of the jig, the weight was gradually applied with a predetermined interval until the
weight reached 30 kg, and then it was taken for 4 hours while maintaining the jig at 50 ° C. The
ultrasonic probe of Comparative Example 3 was produced in the same manner as in Example 1
14-04-2019
25
except that the pressure curing was performed. At this time, the sum of the arithmetic mean
roughness (Ra) of the first adherend and the arithmetic mean roughness (Ra) of the second
adherend was 0.150 μm.
[0081]
Comparative Example 4 By the above-described polishing process, the arithmetic average
roughness (Ra) of the first adherend is 0.343 μm, and the arithmetic average roughness (Ra) of
the second adherend is 0.248 μm. The ultrasonic probe of Comparative Example 4 was
produced in the same manner as Comparative Example 3 except for the above. At this time, the
sum of the arithmetic average roughness (Ra) of the first adherend and the arithmetic average
roughness (Ra) of the second adherend was 0.591 μm.
[0082]
Comparative Example 5 By the above-described polishing process, the arithmetic average
roughness (Ra) of the first adherend is set to 0.459 μm, and the arithmetic average roughness
(Ra) of the second adherend is set to 0.515 μm. An ultrasonic probe of Comparative Example 5
was produced in the same manner as in Comparative Example 3 except for the above. At this
time, the sum of the arithmetic mean roughness (Ra) of the first adherend and the arithmetic
mean roughness (Ra) of the second adherend was 0.974 μm.
[0083]
Comparative Example 6 By the above-described polishing process, the arithmetic average
roughness (Ra) of the first adherend is 0.343 μm, and the arithmetic average roughness (Ra) of
the second adherend is 0.942 μm. The ultrasonic probe of Comparative Example 6 was
produced in the same manner as Comparative Example 3 except for the above. At this time, the
sum of the arithmetic mean roughness (Ra) of the first adherend and the arithmetic mean
roughness (Ra) of the second adherend was 1.285 μm.
[0084]
14-04-2019
26
Comparative Example 7 By the above-described polishing process, the arithmetic average
roughness (Ra) of the first adherend is set to 0.075 μm, and the arithmetic average roughness
(Ra) of the second adherend is set to 0.250 μm. The ultrasonic probe of Comparative Example 7
was produced in the same manner as in Comparative Example 3 except for the above. At this
time, the sum of the arithmetic mean roughness (Ra) of the first adherend and the arithmetic
mean roughness (Ra) of the second adherend was 0.325 μm.
[0085]
(Evaluation) The thickness of the adhesive layer between the piezoelectric layer and the
dematching layer of each of the ultrasonic probes of Examples 1 to 4 and Comparative Examples
1 to 7 manufactured as described above was measured. The results are shown in Table 1.
Further, the arithmetic average roughness (Ra) of the first adherend and the arithmetic average
roughness of the second adherend in Examples 1 to 4 and Comparative Examples 1 and 2 in
which a low viscosity adhesive is used for the adhesive layer. The relationship between the total
value with (Ra) and the thickness of the adhesive layer is shown in FIG. 10 (a), and the arithmetic
mean roughness of the first adherend in Comparative Examples 3 to 7 using a high viscosity
adhesive for the adhesive layer The relationship between the sum of the roughness (Ra) and the
arithmetic average roughness (Ra) of the second adherend and the thickness of the adhesive
layer is shown in FIG. 10 (b).
[0086]
[0087]
(Results) As described above, as in Examples 1 to 4, the low-viscosity adhesive is used, and
through an appropriate pressure-warming adhesion step, the arithmetic mean roughness (Ra of
the first adherend) The thickness of the adhesive layer can be reduced to 0.5 μm or less by
setting the total value of (A) and the arithmetic average roughness (Ra) of the second adherend to
0.4 μm or less, and as a result It has been found that the decrease in sensitivity can be
suppressed to less than -5 dB, and an ultrasonic probe close to an ideal sensitivity state can be
obtained.
Moreover, it turned out that the acoustic characteristic in high frequency can be made into a
favorable ultrasonic probe. On the other hand, according to Comparative Examples 1 to 7, the
14-04-2019
27
bonding layer can not be thinned, and hence the high frequency part of the band is narrowed to
narrow the band, thereby becoming an ultrasonic probe inferior in transmission / reception
sensitivity. all right.
[0088]
As described above, according to the present embodiment, the dematching layer 23 having an
acoustic impedance higher than the acoustic impedance of the piezoelectric layer 24 is thermally
cured on the surface of the piezoelectric layer 24 opposite to the ultrasonic wave output surface.
Are glued with the adhesive. The sum of the arithmetic mean roughness (Ra) of the bonding
surfaces of the piezoelectric layer 24 and the dematching layer 23 bonded by the adhesive is 0.4
μm or less. The viscosity of the adhesive before heat curing is set to 600 cps or less at 40 ° C.
or less. As a result, the thickness of the adhesive layer for bonding the piezoelectric layer and the
dematching layer can be sufficiently reduced, so that the acoustic propagation loss can be
suppressed, and ultrasonic waves with sensitivity close to the ideal can be transmitted and
received. Also, the acoustic characteristics can be improved particularly at high frequencies, and
a broadband ultrasonic probe can be realized.
[0089]
Further, according to the present embodiment, in the first step, the adhesive layer 26 is formed
between the piezoelectric layer 24 and the dematching layer 23 with the adhesive before
thermosetting, at a normal temperature lower than the curing temperature of the adhesive. In
this state, the excess adhesive is released by applying pressure in a direction in which the
piezoelectric layer 24 and the dematching layer 23 face each other for a predetermined time. In
the second step, the adhesive forming the adhesive layer 26 is thermally cured by heating to 50
° C., which is the curing temperature of the adhesive, and pressing for a predetermined time.
The piezoelectric layer 24 and the dematching layer 23 are bonded through the first and second
steps. As a result, the bonding layer can be thinned while maintaining good bonding between the
dematching layer and the piezoelectric layer, and high frequency acoustic characteristics can be
improved.
[0090]
Further, according to the present embodiment, since the adhesive has a glass transition
temperature after heat curing of 50 ° C. or higher, dicing is performed on the laminated body in
which the piezoelectric layer and the dematching layer are laminated. When the element is
14-04-2019
28
formed or when a voltage is applied, it is possible to suppress that the temperature rises and the
adhesive strength of the adhesive decreases, and the peeling can be reduced.
[0091]
Further, according to the present embodiment, since the dematching layer 23 is made of a
tungsten-based alloy, an ultrasonic probe with higher sensitivity can be obtained.
[0092]
Further, according to the present embodiment, since the grain size of the tungsten-based alloy
constituting the dematching layer 23 is 1 μm or less, the adhesion layer can be further thinned.
[0093]
Further, according to the present embodiment, since the thickness of the adhesive layer 26
formed by the adhesive after thermosetting is set to 0.5 μm or less, the sensitivity on the high
frequency side can be further improved. .
[0094]
Further, according to the present embodiment, since the center frequency of the ultrasonic waves
to be transmitted and received is 7 MHz or more, the piezoelectric layer can be efficiently used.
[0095]
Further, according to the present embodiment, the piezoelectric layer 24 and the dematching
layer 23 are divided by the first division grooves at predetermined intervals and separated from
each other, thereby forming a plurality of transducers in the scanning direction.
Each of the plurality of transducers includes a plurality of divided elements formed by being
further divided by a second divided groove parallel to the first divided groove.
As a result, the vibration efficiency of the vibrator can be enhanced.
[0096]
14-04-2019
29
Further, according to the present embodiment, the transmission unit 12 causes the ultrasonic
probe 2 to output the transmission ultrasonic wave by outputting a rectangular wave drive signal
having a plurality of pulses, and among the plurality of pulses, Since at least one pulse width is
made to be different from the pulse width of the other pulse, a wide band transmission ultrasonic
wave can be output by the drive signal.
Therefore, a good transmission ultrasonic wave can be output by the ultrasonic probe having a
wide band acoustic characteristic and the wide band transmission ultrasonic wave.
[0097]
The description in the embodiment of the present invention is an example of the ultrasound
diagnostic imaging apparatus according to the present invention, and the present invention is not
limited to this.
The detailed configuration and the detailed operation of each functional unit constituting the
ultrasound diagnostic imaging apparatus can be appropriately changed.
[0098]
S ultrasound imaging apparatus 2 ultrasound probe 12 transmission unit 14 image generation
unit 23 dematching layer (reflection layer) 24 piezoelectric layer 26 adhesive layer
14-04-2019
30
Документ
Категория
Без категории
Просмотров
0
Размер файла
49 Кб
Теги
description, jp2015036056
1/--страниц
Пожаловаться на содержимое документа