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DESCRIPTION JP2010154382

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DESCRIPTION JP2010154382
PROBLEM TO BE SOLVED: To provide a piezoelectric vibrator of an ultrasonic probe in which the
length in the thickness direction of an ultrasonic probe can be made smaller by shortening the
length of a ground electrode than in the prior art, and the surface of a signal electrode can be
made as smooth as possible. I will provide a. A second filling portion (34) provided on a
piezoelectric body (26) of a piezoelectric vibrator (15) is not ground more than the piezoelectric
portion (32) when the surface of the piezoelectric body (26) is ground. And a protrusion 34a that
protrudes from the surface of the piezoelectric body 26. On the other hand, the first The
agrindability at the time of grinding is formed by a filler of a material which is superior to the
filler forming the second filler 34, and the conductive layer 27 on the projection 34a protrudes
to be a ground electrode. A protrusion 35 is formed on the surface of the surface 29. [Selected
figure] Figure 4
Piezoelectric vibrator of ultrasonic probe, ultrasonic probe, ultrasonic diagnostic apparatus, and
method of manufacturing piezoelectric vibrator in ultrasonic probe
[0001]
The present invention relates to a piezoelectric vibrator of an ultrasonic probe that transmits and
receives ultrasonic waves to and from a subject, an ultrasonic probe, an ultrasonic diagnostic
apparatus, and a method of manufacturing the piezoelectric vibrator in the ultrasonic probe.
[0002]
In an ultrasonic diagnostic apparatus that irradiates ultrasonic waves to a subject and images its
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reflection echo (echo), an ultrasonic probe that transmits and receives ultrasonic waves is
connected to the ultrasonic diagnostic apparatus main body.
The ultrasonic probe includes a piezoelectric vibrator made of a piezoelectric material such as
PZT (lead zirconate titanate), an acoustic matching layer disposed on the ultrasonic wave
irradiation side with respect to the piezoelectric vibrator, and the piezoelectric vibrator. A
backing material layer disposed on the opposite side to the ultrasonic wave irradiation side, and a
flexible substrate interposed between the backing material and the piezoelectric vibrator and
connected to an electrode of the piezoelectric vibrator There is.
[0003]
As the piezoelectric vibrator, a so-called wrap-around electrode structure piezoelectric vibrator in
which a ground electrode is formed on the same surface as the surface on which the signal
electrode is formed and from the surface opposite to the surface on which the signal electrode is
formed. (See, for example, Patent Document 1). In the piezoelectric vibration vibrator, ground
electrodes are formed at both ends so as to sandwich the signal electrode on the surface on
which the signal electrode is formed, and when a voltage is applied to the piezoelectric vibrator,
the signal electrode in the piezoelectric vibrator is The middle portion having the is to be
elastically vibrated. The piezoelectric vibrator having such a wraparound electrode structure has
an advantage that the connection structure can be simplified since the ground electrode and the
signal electrode can be connected to the flexible substrate in the same plane. There is.
[0004]
Further, as the piezoelectric vibrator, there is known a composite piezoelectric body in which a
resin is filled as a filler in a gap formed in a piezoelectric body made of PZT or the like (for
example, see Patent Document 2). This composite piezoelectric body has an effect that the
electromechanical coupling coefficient can be increased as the acoustic impedance becomes
smaller than that of PZT to approach the acoustic impedance of the acoustic matching layer. In
the case where the piezoelectric vibrator having the wraparound electrode structure as described
above is a composite piezoelectric body, the resin is filled in the intermediate portion in which
the signal electrode is formed.
[0005]
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Furthermore, a reflective layer formed of tungsten or the like may be adhered to the surface of
the piezoelectric vibrator opposite to the ultrasonic wave irradiation side. The reflection layer
reflects the ultrasonic wave generated by the elastic vibration of the piezoelectric vibrator to the
direction of the subject (the acoustic matching layer side), and when the resonance vibration by
the piezoelectric vibrator is excited, the reflection is generated. A standing wave is formed with
the layer at the fixed end.
[0006]
Incidentally, the reflection layer is bonded to the signal electrode and the ground electrode when
the piezoelectric vibrator has a wrap-around electrode structure. Here, tungsten forming the
reflective layer has conductivity, and the flexible substrate is connected to the reflective layer,
and is electrically connected to the respective electrodes through the reflective layer. JP, 2007167445, A JP, 2002-232,95 A
[0007]
By the way, in the ultrasonic probe, when the piezoelectric transducers arranged in the scanning
direction of ultrasonic waves become long, the thickness of the ultrasonic probe is increased.
When the ultrasonic probe becomes thick, contact with the body surface of the subject becomes
insufficient when scanning from the intercostal space, especially in the sector type ultrasonic
probe, which is not preferable for imaging. Therefore, it is not desirable for the piezoelectric
vibrator to be long. However, in the case of the piezoelectric vibrator having the wraparound
electrode structure, the piezoelectric vibrator becomes longer by the amount of having the
ground electrode in addition to the signal electrode on one surface. Here, in the piezoelectric
vibrator having a wraparound electrode structure, both ends where the ground electrode is
formed are portions that do not vibrate at the time of transmission and reception of ultrasonic
waves, and are portions that do not directly contribute to transmission and reception of
ultrasonic waves. is there. Therefore, in the related art, the length of the piezoelectric vibrator is
suppressed by shortening the ground electrode as much as possible.
[0008]
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The signal electrode and the ground electrode of the piezoelectric vibrator, and the conductor
such as the flexible substrate or the reflective layer are connected by pressure bonding using an
epoxy resin adhesive or the like. In such a connection structure, the raised portions of the surface
of each electrode of the piezoelectric vibrator and the surface of the conductor or the reflective
layer of the flexible substrate are in contact with each other to establish conduction. There is.
Because of this, in the related art, the length of the ground electrode formed on the same surface
as the signal electrode is such that an area that can ensure conduction with the flexible substrate
can be secured at a minimum. There is. Therefore, the length of the ground electrode can not be
shortened any longer, and if the length of the piezoelectric vibrator is to be shortened, the length
of the signal electrode must be shortened, and the sensitivity is degraded. It will be.
[0009]
Further, in the case of bonding the reflective layer to the piezoelectric vibrator, if the adhesive
surfaces of the piezoelectric vibrator and the reflective layer facing each other have unevenness,
the adhesive is accumulated in the recess, and as a result, the adhesive layer becomes thick. Here,
if the adhesive layer becomes thick, the reflection layer can not be sufficiently functioned as a
fixed end in the resonance vibration excited by the piezoelectric vibrator. As a result, the power
of the ultrasonic wave emitted to the subject side is lost. In addition, even when receiving an
ultrasonic wave, when the reflection layer does not function sufficiently as a fixed end, an echo
signal is transmitted to the reflection layer side, and an echo signal received by the piezoelectric
vibrator becomes small. Therefore, in order to make the adhesive layer between the piezoelectric
vibrator and the reflective layer as thin and uniform as possible, the opposing adhesive surfaces
of the piezoelectric vibrator and the reflective layer are both mirror-polished by grinding to form
asperities. Is suppressed to less than the micron order.
[0010]
However, when the piezoelectric vibrator is formed of a composite piezoelectric material, since
the resin as the filler and the piezoelectric material have different elastic moduli, when the
piezoelectric vibrator is mirror-polished, the resin portion is compressed during grinding As a
result, stress concentrates on the portion of the piezoelectric material. Therefore, the portion of
the piezoelectric material is ground rather than the portion of the resin, and after grinding, the
stress is released and the portion of the resin expands and protrudes. As a result, the unevenness
of the surface of the signal electrode which is the bonding surface with the reflective layer in the
piezoelectric vibrator becomes larger than the micron order, and the adhesive layer with the
reflective layer is made thin and uniform. I can not do it. Therefore, it is desirable to make the
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surface of the signal electrode as smooth as possible, particularly in a piezoelectric vibrator
formed of a composite piezoelectric material.
[0011]
The present invention has been made in view of such circumstances, and the problem to be
solved is to shorten the length of the ground electrode and reduce the dimension in the thickness
direction of the ultrasonic probe than conventional. It is an object of the present invention to
provide a piezoelectric vibrator of an ultrasonic probe, an ultrasonic probe, an ultrasonic
diagnostic apparatus, and a method of manufacturing a piezoelectric vibrator in an ultrasonic
probe, which can make the surface of a signal electrode as smooth as possible.
[0012]
This invention was made in order to solve the said subject, and the invention of a 1st viewpoint is
the same in the signal electrode and ground electrode which are comprised by the conductive
layer provided in the surface of a piezoelectric material in the said piezoelectric material. And a
piezoelectric member formed of a piezoelectric material, wherein the piezoelectric body is a
filling portion formed by filling a filler in a gap formed in the piezoelectric body, and a filling
portion formed of the piezoelectric material And a first filling portion provided in a portion
having the signal electrode in the piezoelectric vibrator as the filling portion, and the ground
formed on the same surface as the signal electrode in the piezoelectric vibrator. And a second
filling portion provided in a portion having an electrode, wherein the second filling portion is not
ground more than the piezoelectric material portion when the surface of the piezoelectric body is
ground, and the surface of the piezoelectric body is not ground. By the filling material of the
material to be projected The first filling portion has a protrusion that protrudes from the surface
of the piezoelectric body, while the first filling portion has a grinding property when the surface
of the piezoelectric body is ground, the second filling portion And the conductive layer on the
protrusion of the second filling portion protrudes to form a protrusion on the surface of the
ground electrode. , And a piezoelectric transducer of an ultrasonic probe.
[0013]
The invention of the second aspect is characterized in that in the invention of the first aspect, the
filler in the first filling portion and the filler in the second filling portion are resins having
different agrinability. It is a piezoelectric vibrator of an ultrasonic probe.
[0014]
The invention of a third aspect is characterized in that, in the invention of the first or second
aspect, a conductor for applying a voltage to the piezoelectric vibrator is surface crimped to the
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signal electrode and the ground electrode. It is a piezoelectric vibrator of an ultrasonic probe.
[0015]
The invention according to the fourth aspect is the invention according to any one of the first to
third aspects, wherein the ground electrode is formed on the same surface as the signal electrode
at both end portions of the piezoelectric body and has the projection. One portion, a second
portion formed on the side opposite to the side on which the first portion is formed in the
piezoelectric body, and the first portion and the second portion in the piezoelectric body And the
signal electrode is sandwiched between the first portion of the ground electrode and the surface
of the middle portion between the two ends of the piezoelectric body. The first filling portion is
provided at an intermediate portion between both ends of the piezoelectric body, while the
second filling portion is provided at both ends of the piezoelectric body. It is a piezoelectric
vibrator of an ultrasonic probe.
[0016]
The invention according to the fifth aspect relates to the invention according to any one of the
first to fourth aspects, wherein a plurality of each of the first filling portion and the second filling
portion is provided, and an interval between the adjacent second filling portions is It is a
piezoelectric vibrator of an ultrasonic probe characterized by being narrower than the interval of
the 1st filling parts which adjoin each other.
[0017]
The invention of a sixth aspect is the invention according to any one of the first to fifth aspects,
wherein the surface of the piezoelectric vibrator on which the signal electrode and the ground
electrode are formed is generated by the piezoelectric vibrator. It is a piezoelectric transducer of
an ultrasonic probe characterized in that a reflection layer for reflecting a sound wave is adhered.
[0018]
An invention of a seventh aspect is an ultrasonic probe including the piezoelectric vibrator
according to the invention of any one of the first to sixth aspects.
[0019]
The invention according to the eighth aspect relates to the ultrasonic wave irradiation according
to the seventh aspect, in which the surface on which the signal electrode and the ground
electrode in the piezoelectric vibrator are formed is opposite to the piezoelectric vibrator. An
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acoustic matching layer disposed on the side, a backing material layer disposed on the side
where the signal electrode and the ground electrode are formed with respect to the piezoelectric
vibrator, the backing material layer, and the piezoelectric vibrator And a flexible substrate
connected between the signal electrode and the ground electrode.
[0020]
The invention according to a ninth aspect is the invention according to the eighth aspect,
wherein the surface of the piezoelectric vibrator on which the signal electrode and the ground
electrode are formed is pressure-bonded to generate the supersonic vibration generated by the
elastic vibration of the piezoelectric vibrator. It is an ultrasonic probe characterized by
comprising a conductive reflection layer for reflecting a sound wave, and the flexible substrate is
connected to the signal electrode and the ground electrode through the reflection layer.
[0021]
An invention of a tenth aspect is an ultrasonic diagnostic apparatus including the ultrasonic
probe according to the invention of any one of the seventh to ninth aspects.
[0022]
The invention according to an eleventh aspect comprises a first groove forming step of forming a
first groove of a predetermined depth in a piezoelectric body made of a piezoelectric material,
and filling the first groove with a filler to form a first filling portion. A first filling portion forming
step of forming, a second groove forming step of forming a second groove of a predetermined
depth in a portion of the piezoelectric body other than the portion where the first groove is
formed, and A second filling portion forming step of filling the second groove with a filler to form
a second filling portion, and grinding for grinding the surface of the piezoelectric body on which
the first filling portion and the second filling portion are formed And a conductive layer forming
step of forming a conductive layer to be a signal electrode and a ground electrode on the surface
of the piezoelectric body subjected to the grinding step, wherein the second groove is formed in
the second filling portion forming step. The filler to be filled in is ground more than the portion
of the piezoelectric material when the surface of the piezoelectric body is ground in the grinding
step. It is a material which will be projected on the surface of the piezoelectric body, and the filler
filled in the first groove in the first filling portion forming step is the surface of the piezoelectric
body in the grinding step. The abradability of the material when grinding is superior to that of
the filling material forming the second filling part, and in the grinding step, a part of the second
filling part protrudes from the surface of the piezoelectric body Grinding is performed so that the
first filling portion does not protrude from the surface of the piezoelectric body, and the
conductive layer is protruded on the protrusion in the conductive layer forming step. A method
of manufacturing a piezoelectric vibrator in an ultrasonic probe characterized in that a projection
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is formed on the surface of the piezoelectric body so that the projection is formed, and a portion
of the conductive layer on which the projection is formed is a ground electrode. It is.
[0023]
According to the present invention, after the gap is formed in the piezoelectric body and the filler
is filled, the surface of the piezoelectric body is ground before the conductive layer is provided on
the surface of the piezoelectric body. The protrusion of the second filling portion may be formed.
Then, by providing the conductive layer on the surface of the piezoelectric body on which the
protrusion of the second filling portion is formed as described above, the conductive layer on the
protrusion protrudes and the protrusion is formed on the surface of the ground electrode. The
part can be formed.
Since this projection can ensure conduction between the ground electrode and the conductor to
be crimped to apply a voltage to the piezoelectric vibrator, the length of the ground electrode can
be made shorter than in the prior art. it can.
Therefore, the piezoelectric vibrator can be made shorter than in the prior art without
deteriorating the sensitivity, whereby the dimension in the thickness direction of the ultrasonic
probe can be reduced.
[0024]
In addition, although the piezoelectric body is a composite piezoelectric body in which a first
filling portion is formed in a portion having the signal electrode, the first filling portion has a
grinding property when the surface of the piezoelectric body is ground. Since the filler of the
material superior to the filler forming the second filler is formed, the first filler is ground by
grinding the surface of the piezoelectric body before the conductive layer is provided. It can be
formed so as not to protrude from the surface of the piezoelectric body.
Therefore, the surface of the signal electrode formed of the conductive layer formed on the
surface of the piezoelectric body can be made as smooth as possible, so that the adhesive layer
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between the signal electrode and the conductor crimped by the adhesive can be made as small as
possible. It can be thin and uniform.
[0025]
Furthermore, since the smoothness of the surface of the signal electrode is high, while the
projection is formed on the surface of the ground electrode, the average thickness of the
piezoelectric vibrator is greater than that of the portion having the signal electrode. Also, the
portion having the ground electrode is thicker.
Thereby, stress when the conductor is crimped to the signal electrode and the ground electrode
formed on the same surface of the piezoelectric vibrator can be concentrated on the ground
electrode, and the ground electrode and the conductor Can be crimped firmly.
Therefore, it can be said from this that it is possible to make the length of the ground electrode
shorter than conventional.
[0026]
Further, the first filling part and the second filling part may be respectively provided in plurality,
and the distance between the adjacent second filling parts may be smaller than the distance
between the adjacent first filling parts. The distance between the protrusions formed on the
protrusions of the second filling portion becomes narrower.
As a result, the average thickness of the portion having the ground electrode in the piezoelectric
vibrator becomes thicker, so surface bonding of the signal electrode, the ground electrode, and a
conductor for applying a voltage to the piezoelectric vibrator is performed. In this state, stress
applied to the pressure contact surface is concentrated on the ground electrode.
Therefore, the pressing force between the ground electrode and the conductor can be
strengthened.
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[0027]
Hereinafter, embodiments of the present invention will be described in detail based on the
drawings.
First Embodiment A first embodiment will be described.
FIG. 1 is a block diagram showing a schematic configuration of an example of an embodiment of
an ultrasonic diagnostic apparatus according to the present invention, and FIG. 2 is a partially
cutaway perspective view showing an appearance of an ultrasonic probe in the ultrasonic
diagnostic apparatus shown in FIG. FIG. 3 is a perspective view showing the appearance of the
functional element portion in the ultrasonic probe of the first embodiment, FIG. 4 is a sectional
view of the functional element portion shown in FIG. 3, and FIG. 5 constitutes the functional
element portion 6 to 11 are schematic explanatory views of a manufacturing process of the
piezoelectric vibrator.
[0028]
First, a schematic configuration of an example of an embodiment of an ultrasonic diagnostic
apparatus according to the present invention will be described based on FIG.
As shown in FIG. 1, the ultrasonic diagnostic apparatus 100 includes an ultrasonic probe 101
and an ultrasonic diagnostic apparatus main body 102 to which the ultrasonic probe 101 is
connected.
[0029]
The ultrasonic probe 101 is a sector type probe in this example as shown in FIG. 2, and transmits
ultrasonic waves to the subject and ultrasonic echoes obtained for the transmission of the
ultrasonic waves. Receive
The detailed configuration of the ultrasonic probe 101 will be described later.
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[0030]
The ultrasonic diagnostic apparatus main body 102 includes a transmission / reception unit 103,
an image processing unit 104, a display unit 105, a control unit 106, and an operation unit 107.
The transmission / reception unit 103 drives the ultrasonic probe 101 to transmit ultrasonic
waves, and performs signal processing such as phasing addition processing on ultrasonic echoes
received by the ultrasonic probe 101.
[0031]
The image processing unit 104 creates an ultrasonic image such as a B-mode image based on the
echo signal subjected to signal processing by the transmission / reception unit 103. Then, the
ultrasonic image created by the image processing unit 104 is displayed on the display unit 105.
[0032]
In the operation unit 107, various instructions are input by the operator. The operation unit 107
outputs an instruction signal to the control unit 106 when an instruction is input. The control
unit 106 controls each unit of the ultrasonic diagnostic apparatus main body 102 based on an
instruction signal from the operation unit 107 and a program stored in advance.
[0033]
The ultrasonic probe 101 will be described in detail. As shown in FIG. 2, the ultrasonic probe 101
has an acoustic lens unit 10 at its tip. The ultrasonic probe 101 further includes a probe housing
11 and a connection cable 12 for connecting to the ultrasonic diagnostic apparatus main body
102.
[0034]
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A functional element unit 13 is provided in the probe housing 11. The functional element unit 13
will be described in detail based on FIGS. 3 and 4. The functional element unit 13 includes an
acoustic matching layer 14, a piezoelectric vibrator 15, an adhesive layer 16, a reflective layer
17, a backing material layer 18, and a flexible substrate 19. The acoustic matching layer 14
having the shape of a rectangular solid elongated in the x-axis direction, the piezoelectric vibrator
15 and the reflection layer 17 are stacked in the z-axis direction which is a direction along the
irradiation direction of the ultrasonic wave, Configure. Then, a plurality of the stacked bodies 20
are arranged in the y-axis direction.
[0035]
The acoustic matching layer 14 is bonded to a plate surface on the ultrasonic wave irradiation
direction side of the piezoelectric vibrator 15 (the adhesive layer is not shown). The acoustic
matching layer 14 has an acoustic impedance intermediate between the piezoelectric vibrator 15
and the acoustic lens unit 10. In addition, the acoustic matching layer 14 has a thickness of
about 1⁄4 wavelength of the transmitted ultrasonic wave, and suppresses reflection at the
interface between different acoustic impedances. In addition, although the acoustic matching
layer 14 is illustrated as an example of one layer in this example, it may be two layers or multiple
layers. The acoustic matching layer 14 is an example of the embodiment of the acoustic matching
layer in the present invention.
[0036]
The reflection layer 17 is pressure-bonded to the surface of the piezoelectric vibrator 15
opposite to the acoustic matching layer 14 by the adhesive layer 16 made of an epoxy resin
adhesive or the like. The reflection layer 17 reflects the ultrasonic wave generated toward the
reflection layer 17 by the elastic vibration of the piezoelectric vibrator 15 in the direction of the
object. The reflective layer 17 is an example of the embodiment of the reflective layer in the
present invention.
[0037]
Incidentally, when the resonance vibration by the piezoelectric vibrator 15 is excited by the
voltage applied between the signal electrode 28 and the ground electrode 29 of the piezoelectric
vibrator 15 described later, the standing with the reflection layer 17 as the fixed end A wave is
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formed. The standing wave is a standing wave in which the thickness of the piezoelectric vibrator
15 is a quarter wavelength.
[0038]
The material of the reflective layer 17 is preferably one having a high acoustic impedance in
order to reflect an ultrasonic wave, and tungsten (tungsten) or the like is used. The tungsten has
conductivity, and the reflection layer 17 is formed of a first copper foil layer 22 and a second
copper foil layer 23 of the flexible substrate 19 described later, the signal electrode 28 of the
piezoelectric vibrator 15, and the ground. It has a function of electrically connecting to the
electrode 29. Thereby, a voltage supplied from the first copper foil layer 22 and the second
copper foil layer 23 is applied to the piezoelectric vibrator 15 through the reflection layer 17. In
the present invention, the reflective layer 17 is an example of an embodiment of a conductor that
is pressure-bonded to the signal electrode and the ground electrode to apply a voltage to the
piezoelectric vibrator.
[0039]
In order to make the adhesive layer 16 as thin and uniform as possible, the reflective layer 17 is
mirror-polished on the adhesive surface 17 a with the piezoelectric vibrator 15.
[0040]
Drilling holes 21 and 21 are formed at both ends of the reflective layer 17, the adhesive layer 16,
and the piezoelectric vibrator 15 in the longitudinal direction.
The drill holes 21 and 21 are formed, for example, by bonding the piezoelectric vibrator 15 and
the reflective layer 17 with the adhesive layer 16 and then cutting the reflective layer 17 with a
diamond grindstone or the like.
[0041]
The flexible substrate 19 is pressure bonded to the surface of the reflective layer 17 opposite to
the adhesive surface 17a with the piezoelectric vibrator 15 using an adhesive (adhesive layer) Is
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not shown). The flexible substrate 19 is drawn out along the side surface in the thickness
direction of the backing material layer 18 and connected to the connection cable 12 (the
connection structure is not shown).
[0042]
The structure of the flexible substrate 19 will be described. As shown in FIG. 4, the flexible
substrate 19 has a first copper foil layer 22, a second copper foil layer 23, a first polyimide film
layer 24 and a second polyimide. It consists of four layers of the membrane layer 25. The first
copper foil layer 22 and the second copper foil layer 23 are mutually insulated by the first
polyimide film layer 24. The first copper foil layer 22 is formed so as to be positioned closer to
both ends of the reflection layer 17 than the drill holes 21, 21 in a state of being bonded to the
reflection layer 17. Further, the second copper foil 23 is laminated between the first polyimide
film layer 24 and the second polyimide film layer 25, and on the central portion side of the
reflection layer 17 more than the digging holes 21 and 21. Are also present in the same plane as
the first copper foil layer 22 through the through holes H. The first copper foil layer 22 and the
second copper foil layer 23 present in the same plane are mutually insulated by the dividing
groove G. The division grooves G are formed to be at the positions of the drill holes 21 and 21 in
a state where the flexible substrate 19 is bonded to the reflection layer 17. Thus, the first copper
foil layer 22 is electrically connected to the end of the conductive reflective layer 17 more than
the holes 21 and 21, while the second copper foil layer 23 is The reflection layer 17 is
electrically connected to the intermediate portion between the drill holes 21 and 21. Therefore,
the first copper foil layer 22 is electrically connected to first portions 29 a and 29 a of the
ground electrode 29 of the piezoelectric vibrator 15 described later via the reflective layer 17,
and the second copper foil The layer 23 is electrically connected via the signal electrode 28 of
the piezoelectric vibrator 15 and the reflection layer 17.
[0043]
Incidentally, the first copper foil layer 22 connected to the ground electrode 29 is formed on the
entire surface of the flexible substrate 19, and the ground electrodes 29 of all the piezoelectric
vibrators 15 arranged in the y-axis direction. Conduction is common. On the other hand, the
second copper foil layer 23 is divided into a plurality of parts in the y-axis direction by copper
foil layer dividing grooves (not shown), and has a plurality of copper foil patterns (not shown)
formed in the flexible substrate 19. The copper foil pattern is formed for each of the laminates
20 arranged in the y-axis direction.
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[0044]
The backing material layer 18 is bonded to the flexible substrate 19 or is formed directly on the
back surface of the flexible substrate 19 to hold the flexible substrate 19. The backing material
layer 18 is an example of the embodiment of the backing material layer in the present invention.
[0045]
Next, the piezoelectric vibrator 15 will be described with reference to FIGS. 3 and 4 as well as
FIG. The piezoelectric vibrator 15 has a conductive layer 27 formed by sputtering or the like on
the surface of the piezoelectric body 26. The conductive layer 27 constitutes a signal electrode
28 and a ground electrode 29. The piezoelectric body 26, the conductive layer 27, the signal
electrode 28, and the ground electrode 29 are examples of embodiments of the piezoelectric
body, the conductive layer, the signal electrode, and the ground electrode in the present
invention, respectively.
[0046]
The signal electrode 28 is formed in an intermediate portion 26 a between the drill holes 21 and
21 in the piezoelectric body 26. Further, the ground electrode 29 is formed at the end portions
26b and 26b of the piezoelectric body 26 with the first portion 29a and 29a formed on the same
surface so as to separate the signal electrode 28 and the drilling holes 21 and 21; A second
portion 29b formed on the surface opposite to the surface on which the first portions 29a and
29a are formed in the piezoelectric body 26, and the first portions 29a and 29a and the second
portion in the piezoelectric body 26 And the third portions 29c, 29c formed on the side surfaces
between the portions 29b. The signal electrode 28 is formed so as to be sandwiched between the
first portions 29 a and 29 a of the ground electrode 29, and the two electrodes 28 and 29 are
electrically insulated by the drill holes 21 and 21. There is. The first portions 29 a and 29 a of
the signal electrode 28 and the ground electrode 29 are crimped to the reflective layer 17. The
first portion 29a, the second portion 29b and the third portion 29c are an example of
embodiments of the first portion, the second portion and the third portion in the present
invention. .
[0047]
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The piezoelectric body 26 is composed of a filling portion 31 formed by filling the space 30 with
a filling material, and a piezoelectric material portion 32 made of a piezoelectric material such as
PZT. The piezoelectric body 26 has a first filling portion 33 described later as the filling portion
31 in an intermediate portion 26 a having the signal electrode 28 and is a composite
piezoelectric body. The filling part 31 and the piezoelectric material part 32 are an example of
the embodiment of the filling part and the piezoelectric material part in the present invention,
respectively.
[0048]
As the filling portion 31, a first filling portion 33 provided in the middle portion 26a of the
piezoelectric body 26, and a second filling portion 34 provided at both ends of the piezoelectric
body 26, ie, the end portions 26b and 26b. have. The first filling portion 33 and the second filling
portion 34 are respectively an example of the embodiment of the first filling portion and the
second filling portion in the present invention. A plurality of the first filling parts 33 and the
second filling parts 34 are respectively formed, and in this example, the spacing T1 between the
adjacent first filling parts 33 and the spacing between the adjacent second filling parts 34 It is
equal to T2.
[0049]
The first filling unit 33 and the second filling unit 34 will be further described. First, the second
filling portion 34 will be described. When the surface of the piezoelectric body 26 is ground, the
second filling portion 34 is not ground more than the piezoelectric portion 32 and protrudes on
the surface of the piezoelectric body 26. The projections 34 a and 34 a are formed of a filler
material of the material to be formed, and project from the surface of the piezoelectric body 26.
The protrusions 34a, 34a are an example of the embodiment of the protrusions in the present
invention.
[0050]
The first filling portion 33 is formed of a filling material of a material whose grinding property
when grinding the surface of the piezoelectric body 26 is superior to the filling material forming
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the first filling portion 33. Unlike the second filling portion 34, the first filling portion 33 does
not protrude from the surface of the piezoelectric body 26. Therefore, the surface of the middle
portion 26a of the piezoelectric body 26 is smooth.
[0051]
Here, the filler which forms each said filling part 33 and 34 is demonstrated concretely. As the
filling material forming the filling portions 33 and 34, resins having different agrinability are
used, and in this example, epoxy resins having different agrinability are used. That is, as the filler
forming the second filling portion 34, when the surface of the piezoelectric body 26 is ground, a
protrusion that protrudes from the surface of the piezoelectric body 26 without being ground
than the piezoelectric material portion 32. The epoxy resin from which 34a and 34a are formed
is used. On the other hand, as a filler for forming the first filling portion 33, the elastic modulus is
lower than that of the filler for forming the second filling portion 34, and the agrindability when
the surface of the piezoelectric body 26 is ground is An epoxy resin that is superior to the epoxy
resin that forms the second filling portion 34 is used. Furthermore, with regard to the filler of the
first filling portion 33, the epoxy resin forming the first filling portion 33 is the first from the
surface of the piezoelectric body 26 when the surface of the piezoelectric body 26 is ground. It is
an epoxy resin of the material which has the grindability which can suppress the protrusion of
the filling part 33. As shown in FIG.
[0052]
The conductive layer 27 protrudes above the protrusions 34 a, 34 a, and the first portion 29 a
and the second portion 29 b of the ground electrode 29 have a protrusion 35. The protrusion 35
is an example of the embodiment of the protrusion in the present invention. Here, although the
adhesive layer 16 is interposed between the piezoelectric vibrator 15 and the reflective layer 17,
the adhesive layer 16 is not interposed between the protrusion 35 and the reflective layer 17.
Thereby, the projection 35 and the reflection layer 17 are in contact with each other and are
conducted to each other.
[0053]
Now, a method of manufacturing the piezoelectric vibrator 15 configured as described above will
be described based on FIGS. First, as shown in FIG. 6, a first groove 40 of a predetermined depth
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is formed in the middle portion 26a of the piezoelectric body 26 (a first groove forming step).
The first groove 40 constitutes the gap 30 (see FIGS. 4 and 5) in the piezoelectric vibrator 15.
Next, as shown in FIG. 7, the first groove 40 is filled with a filler made of epoxy resin to form the
first filling portion 33 (first filling portion forming step).
[0054]
Next, as shown in FIG. 8, a second groove 41 having a predetermined depth is formed at the end
portions 26 b and 26 b of the piezoelectric body 26 (second groove forming step). The second
groove 41 also constitutes the gap 30. Then, as shown in FIG. 9, the second groove 41 is filled
with an epoxy resin different from the epoxy resin filled in the first groove 40 as a filler to form
the second filled portion 34. (2nd filling part formation process). However, at this time, the
second filling portion 34 does not have the protrusions 34a and 34a.
[0055]
After the epoxy resin constituting each of the filling portions 33 and 34 is cured, as shown in FIG.
10, both surfaces of the piezoelectric body 26 are ground (grinding step). At this time, the second
filling portion 34 is compressed because its elastic modulus is lower than that of the piezoelectric
member portion 32 and the first filling portion 33, and the piezoelectric member portion 32 and
the first filling portion 34 are smaller than A large stress is applied to the filling portion 33.
Therefore, the piezoelectric material portion 32 and the first filling portion 33 are ground more
than the second filling portion 34, and after grinding, the second filling portion 34 expands and
protrudes on the surface of the piezoelectric body 26, The protrusions 34a, 34a are formed. On
the other hand, the first filling portion 33 is ground in the same manner as the piezoelectric
member portion 32, and in the piezoelectric body 26, the middle portion 26a having the first
filling portion 33 has a smooth surface.
[0056]
After the grinding step, as shown in FIG. 11, the conductive layer 27 is formed on the surface of
the piezoelectric body 26 by sputtering or the like (conductive layer forming step). The
conductive layer 27 is formed such that the protrusion 35 is formed on the protrusions 34 a and
34 a.
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[0057]
By the way, after bonding the piezoelectric vibrator 15 obtained through each of the above steps
with the reflective layer 17 and the adhesive layer 16, cutting is performed from the reflective
layer 17 side to cut the excavated holes 21 and 21 (FIG. Then, the signal electrode 28 and the
ground electrode 29 are formed by forming (not shown). The piezoelectric vibrator 15 obtained
through the above-described steps is a plate-like body having substantially the same length in the
longitudinal direction and the lateral direction, and the piezoelectric vibrator 15 formed of the
plate-like body is used as the backing material layer 18. After laminating on the flexible substrate
19, by dividing in the y-axis direction, strip-shaped piezoelectric vibrators 15 arranged in the yaxis direction are formed.
[0058]
According to the present embodiment described above, since the projection 35 formed on the
ground electrode 29 can ensure the conduction between the ground electrode 29 and the
reflective layer 17, it is identical to the signal electrode 28. The lengths of the first portions 29a,
29a of the ground electrode 29 formed on the surface can be made shorter than in the prior art.
Therefore, the piezoelectric vibrator 15 can be made shorter than in the prior art without
deteriorating the sensitivity, whereby the dimension in the thickness direction (x-axis direction)
of the ultrasonic probe 101 can be reduced.
[0059]
Further, the first filling portion 33 does not protrude to the surface of the piezoelectric body 26,
and the surface of the intermediate portion 26 a of the piezoelectric body 26 can be smoothed.
As a result, the irregularities on the surface of the signal electrode 28 can be suppressed to less
than a micron order, and as smooth as possible, the adhesive layer 16 can be made as thin and
uniform as possible. Thereby, the adhesive layer 16 does not prevent the function as the fixed
end of the reflection layer 17 in the resonance vibration excited by the piezoelectric vibrator 15,
and the power of the ultrasonic wave emitted to the object side is increased. can do. In addition,
since the adhesive layer 16 does not interfere with the function as the fixed end of the reflection
layer 17 even when receiving an ultrasonic wave, the piezoelectric vibrator 15 attempts to
transmit an echo signal to be transmitted to the reflection layer 17 side. This can be limited to
the inside, and the echo signal received by this piezoelectric vibrator 15 can be enlarged.
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[0060]
Furthermore, since the smoothness of the surface of the signal electrode 28 is high, while the
protrusion 35 is formed on the surface of the ground electrode 29, the average thickness of the
piezoelectric vibrator 15 is the signal electrode The end portions 26 b and 26 b having the
ground electrode 29 are thicker than the intermediate portion 26 a having 28. Thereby, stress
when the reflection layer 17 is pressure-bonded to the first portion 29a of the signal electrode
28 and the ground electrode 29 can be concentrated on the first portion 29a of the ground
electrode 29, and the ground The electrode 29 and the reflective layer 17 can be firmly pressurebonded. Therefore, it can be said from this that it is possible to make the length of the ground
electrode 29 shorter than conventional.
[0061]
Second Embodiment Next, a second embodiment will be described. FIG. 12 is a cross-sectional
view of a functional element portion in the ultrasonic probe of the second embodiment. In
addition, about the structure same as 1st embodiment, the same code | symbol is attached |
subjected and description is abbreviate | omitted.
[0062]
In the piezoelectric vibrator 50 of the present example shown in FIG. 12, the interval T2 between
the adjacent second filling parts 34 is narrower than the interval T1 between the adjacent first
filling parts 33. Since the space T1 between the adjacent first filling portions 33 is the same as
that in the first embodiment, the space T2 between the adjacent second filling portions 34 is
narrower than in the first embodiment.
[0063]
The piezoelectric vibrator 50 of this example is also manufactured through basically the same
manufacturing process as the manufacturing process of the piezoelectric vibrator 15 of the first
embodiment. However, in the second groove forming step, as shown in FIG. 13, the distance T2
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between the adjacent second grooves 41 is narrower than the distance T1 between the adjacent
first grooves 40, The second groove 41 is formed.
[0064]
According to the piezoelectric vibrator 50 of the present embodiment, the interval T2 between
the adjacent second filling parts 34 is narrower than the interval T1 between the adjacent first
filling parts 33, and the adjacent ones are more adjacent than in the first embodiment. Since the
space T2 between the second filling portions 34 is narrow, the space between the adjacent
protruding portions 35 is narrower than in the first embodiment. Thereby, in the piezoelectric
vibrator 15, the average thickness of both ends where the first portions 29 a and 29 a of the
ground electrode 29 are formed can be made thicker, so that the first portion of the ground
electrode 29 can be increased. 29a and the reflective layer 17 can be more firmly pressurebonded.
[0065]
As mentioned above, although the present invention was explained by each above-mentioned
embodiment, it is needless to say that the present invention can be variously changed in the
range which does not change the main point. For example, the protrusion 35 may be provided
only on the first portion 29 a side of the ground electrode 29 formed on the same surface as the
signal electrode 28.
[0066]
The functional element unit 13 may not have the reflective layer 17. In this case, the flexible
substrate 19 is pressure-bonded to the surface of the piezoelectric vibrator 15 opposite to the
acoustic matching layer 14 using an adhesive.
[0067]
Further, the second filling portion 34 may be thicker than the first filling portion 33, and the tip
of the second filling portion 34 may be easily protruded from the surface of the piezoelectric
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body 26 by grinding. In this case, since the first filling portion 33 is thinner than the second
filling portion 34, the surface of the intermediate portion 26 of the piezoelectric body 26 can be
easily smoothed by grinding.
[0068]
It is a block diagram showing a schematic structure of an example of an embodiment of an
ultrasound diagnostic device concerning the present invention. It is a partially cutaway
perspective view which shows the external appearance of the ultrasound probe in the ultrasound
diagnosing device shown in FIG. It is a perspective view which shows the external appearance of
the functional element part in the ultrasonic probe of 1st embodiment. It is sectional drawing of
the functional element part shown in FIG. It is a perspective view which shows the piezoelectric
vibrator which comprises a functional element part. It is a schematic explanatory drawing which
shows the 1st groove | channel formation process in the manufacturing process of a piezoelectric
vibrator. It is a schematic explanatory drawing which shows the 1st filling part formation process
in the manufacturing process of a piezoelectric vibrator. It is a schematic explanatory drawing
which shows the 2nd groove formation process in the manufacturing process of a piezoelectric
vibrator. It is a schematic explanatory drawing which shows the 2nd filling part formation
process in the manufacturing process of a piezoelectric vibrator. It is a schematic explanatory
drawing which shows the grinding process in the manufacturing process of a piezoelectric
vibrator. It is a schematic explanatory drawing which shows the conductive layer formation
process in the manufacturing process of a piezoelectric vibrator. It is sectional drawing of the
functional element part in the ultrasonic probe of 2nd embodiment. It is a schematic explanatory
drawing which shows the 2nd groove | channel formation process in the manufacturing process
of the piezoelectric vibrator in 2nd embodiment.
Explanation of sign
[0069]
14 acoustic matching layer 15, 50 piezoelectric vibrator 17 reflection layer 18 backing material
layer 19 flexible substrate 26 piezoelectric body 26 a middle portion 26 b end portion 27
conductive layer 28 signal electrode 28 a first portion 28 b second portion 28 c third portion
Reference Signs List 29 ground electrode 30 gap 31 filling portion 32 piezoelectric material
portion 33 first filling portion 34 second filling portion 34 a protrusion 35 projection portion 40
first groove 41 second groove 100 ultrasonic diagnostic device 101 ultrasonic probe
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