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DESCRIPTION JP2015142173

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DESCRIPTION JP2015142173
PROBLEM TO BE SOLVED: To provide a laminated ultrasonic vibration device which can be
manufactured at low cost and which prevents the piezoelectric body from being damaged by the
stress caused by the difference between the thermal expansion coefficient of the metal block as
the mass material and the piezoelectric body. . SOLUTION: A multilayer ultrasonic vibration
device is provided with a plurality of piezoelectric members 61 between two mass members 42
and 43, and has elastic constants more than those of the two mass members 42 and 43 and the
plurality of piezoelectric members 61. A plurality of piezoelectric members 61, which are
homogeneous material joints, are joined by a first metal joint layer having a first thickness d1
using brazing materials 73 and 76 having small The piezoelectric body 61 and the mass
members 42 and 43 are joined by a second metal bonding layer having a second thickness d2
thicker than the first thickness d1. [Selected figure] Figure 10
Stacked ultrasonic vibration device and ultrasonic medical device
[0001]
The present invention relates to a laminated ultrasonic vibration device for exciting ultrasonic
vibration, and an ultrasonic medical apparatus provided with the laminated ultrasonic vibration
device.
[0002]
Among ultrasonic treatment tools for coagulating / incising living tissue using ultrasonic
vibration, there is one in which an ultrasonic vibrator using a piezoelectric vibrator is built in a
hand piece as an ultrasonic vibration source in a handpiece.
14-04-2019
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[0003]
In such an ultrasonic vibrator, a piezoelectric element that converts an electrical signal to
mechanical vibration is sandwiched between two block-shaped metal members serving as a front
mass or a back mass, and is integrated in some way including adhesion etc. There is one that
they vibrate together.
Such an ultrasonic transducer is called a Langevin transducer.
[0004]
As a method of integrating a piezoelectric element and a metal member, for example, a boltclamped Langevin vibration in which a piezoelectric element is sandwiched between two metal
members, is firmly fastened by a bolt, and the whole is integrally vibrated. The child is known.
[0005]
Generally, a piezoelectric element used for such a bolt-clamped Langevin vibrator is made of lead
zirconate titanate (PZT, Pb (Zrx, Ti1-x) O3), and the shape of the piezoelectric element is
processed into a ring shape. The bolt is pushed inside.
[0006]
PZT has high productivity and high electromechanical conversion efficiency, and has excellent
characteristics as a piezoelectric material, and has been used for many years in various fields
such as ultrasonic transducers and actuators.
[0007]
However, since PZT uses lead, it has recently been desired to use a lead-free piezoelectric
material which does not use lead from the viewpoint of adverse effects on the environment.
A piezoelectric single crystal lithium niobate (LiNbO3) is known as such a lead-free piezoelectric
material having high electromechanical conversion efficiency.
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[0008]
Conventionally, as a configuration for realizing a Langevin vibrator using lithium niobate at low
cost, a method of integrally bonding while sandwiching a piezoelectric element by a metal block
has been known conventionally.
In particular, when bonding is performed using a brazing material such as solder without using
an adhesive as a method of bonding the metal block and the piezoelectric element, the Langevin
vibrator can obtain better vibration characteristics than the adhesive.
[0009]
However, when a metal block and a piezoelectric element are joined by a brazing material such
as solder, a high temperature process is generally required, and a thermal stress causes a
piezoelectric single crystal to be joined at a joint of different materials as a joined portion of the
metal block and the piezoelectric element. There is a problem that the piezoelectric element is
broken.
[0010]
As a technique for solving such a problem, for example, an ultrasonic vibrator disclosed in Patent
Document 1 is disclosed.
In this conventional ultrasonic vibrator, a structure such as a groove or a recess is provided in
the bonding surface of each metal block bonded by an adhesive to the electrodes provided on the
upper and lower surfaces of the piezoelectric vibrator, and shear generated during driving There
are known techniques for suppressing the occurrence of distortion, reducing the dielectric loss at
the bonding surface, and the like, preventing the occurrence of cracks in the piezoelectric
vibrator, and stabilizing the vibration mode.
[0011]
JP, 2008-128875, A
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[0012]
However, in the conventional ultrasonic vibrator disclosed in Patent Document 1, there is a
problem that a processing step is required on the surface of the metal block and the
manufacturing cost is increased.
[0013]
That is, the conventional ultrasonic vibrator absorbs the thermal stress generated at the joint
between dissimilar materials when bonding the metal block and the piezoelectric element by
bonding, and the stress generated by the cure shrinkage of the adhesive, etc. Since the structure
such as a groove or a recess is provided in the case, an extra processing process is required,
which causes a problem of cost increase.
[0014]
Further, when a thermosetting adhesive is used to bond and fix the piezoelectric vibrator and the
metal block, the conventional ultrasonic vibrator heats the vicinity of the bonding surface when
the adhesive is cured.
Thus, in the conventional ultrasonic vibrator, after curing of the adhesive, a shear strain
corresponding to the temperature difference between the bonding temperature and the normal
temperature may occur due to the difference in the thermal expansion coefficient of the
piezoelectric vibrator and the metal block. is there.
[0015]
Then, residual stress always exists on the bonding surface of the piezoelectric vibrator and the
metal block, and there is also a problem that a crack is generated inside the piezoelectric vibrator
due to this.
[0016]
Therefore, the present invention has been made in view of the above circumstances, and can be
manufactured at low cost, and the piezoelectric vibrator can be manufactured by the stress
caused by the difference between the thermal expansion coefficients of the metal block as the
mass material and the piezoelectric body. An object of the present invention is to provide a
laminated ultrasonic vibration device and an ultrasonic medical device in which breakage or the
like is prevented.
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[0017]
The laminated ultrasonic vibration device according to one aspect of the present invention is a
laminated ultrasonic vibration device in which a plurality of piezoelectric bodies are provided
between two mass members, which is more effective than the two mass members and the
plurality of piezoelectric bodies. A brazing material having a small elastic constant, that is, a soft
brazing material, is used to join the plurality of piezoelectric bodies to be joined of the same
material by the first metal joining layer having the first thickness, and the dissimilar material is
The plurality of piezoelectric bodies to be joined and the mass material are joined by a second
metal joining layer having a second thickness which is thicker than the first thickness.
In the ultrasonic medical device according to one aspect of the present invention, a brazing
material having a plurality of piezoelectric bodies provided between two mass members and
having a smaller elastic constant than the two mass members and the plurality of piezoelectric
bodies, ie, A plurality of piezoelectric members which are joined by a first metal joining layer
having a first thickness and which is a joint of similar materials by using a soft brazing material;
Laminated ultrasonic vibration device joined by a second metal joint layer having a second
thickness thicker than the first thickness, and the laminated ultrasonic vibration device And a
probe tip for transmitting the ultrasonic vibration to treat the living tissue.
[0018]
According to the present invention, it is possible to manufacture at low cost, and it is also
possible to prevent the piezoelectric body from being damaged by the stress caused by the
difference in thermal expansion coefficient between the metal block as the mass material and the
piezoelectric body. And an ultrasound medical device can be provided.
[0019]
The sectional view showing the whole composition of the ultrasonic medical equipment
concerning one mode of the present invention. The figure showing the outline composition of the
whole vibrator unit. The perspective view showing the composition of an ultrasonic vibrator. The
same. The side view showing the configuration The same, a perspective view showing the
piezoelectric single crystal wafer The same, a perspective view showing the piezoelectric single
crystal wafer on which the base metal is formed film the same, a perspective view showing the
piezoelectric single crystal wafer to be diced Same, the piezoelectric single crystal wafer A
perspective view showing a piezoelectric single crystal body cut out from a wafer, an exploded
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perspective view of a transducer unit including an ultrasonic transducer, a cross-sectional view
before mounting a flexible printed circuit board on an ultrasonic transducer of the transducer
unit, Cross-sectional view after mounting a flexible printed circuit board on an ultrasonic
transducer of a transducer unit: the same, a perspective view showing a transducer unit having
an FPC mounted on an ultrasonic transducer, and heat of a mass material relative to the
thickness of a bonding metal expansion Exploded perspective view illustrating the graph showing
the relationship between the thermal stress generated in the piezoelectric single crystal body
from the difference in the number, an example of a bonding metal which is provided between the
mass member and the piezoelectric single crystal body
[0020]
Hereinafter, the present invention will be described using the drawings.
In the following description, the drawings based on the respective embodiments are schematic,
and the relationship between the thickness and the width of each portion, the ratio of the
thickness of each portion, and the like are different from the actual ones. It should be noted that
there may be parts where the relationships and proportions of dimensions differ from one
another among the drawings.
[0021]
First, an embodiment of an ultrasonic medical apparatus provided with a laminated ultrasonic
vibration device for exciting ultrasonic vibration according to one aspect of the present invention
will be described below based on the drawings.
FIG. 1 is a cross-sectional view showing the entire configuration of the ultrasonic medical device,
FIG. 2 is a view showing the general configuration of the transducer unit, FIG. 3 is a perspective
view showing the configuration of the ultrasonic transducer, and FIG. 5 is a perspective view
showing a piezoelectric single crystal wafer, FIG. 6 is a perspective view showing a piezoelectric
single crystal wafer on which a base metal is formed, and FIG. 7 is a piezoelectric single crystal
wafer to be diced 8 is a perspective view showing a piezoelectric single crystal body cut out from
a piezoelectric single crystal wafer, FIG. 9 is an exploded perspective view of a transducer unit
including an ultrasonic transducer, and FIG. 11 is a cross-sectional view after mounting a flexible
printed circuit on an ultrasonic transducer of a transducer unit, and FIG. 12 is a vibration in
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which an FPC is mounted on an ultrasonic transducer. 13 is a perspective view showing a child
unit. A graph showing the relationship between the thermal stress generated in the piezoelectric
single crystal from the difference between the thermal expansion coefficient with the mass and
the thickness of the metal, and FIG. 14 shows an example of the bonding metal provided between
the mass and the piezoelectric single crystal It is a disassembled perspective view.
[0022]
(Ultrasonic Medical Device) The ultrasonic medical device 1 shown in FIG. 1 mainly uses a
transducer unit 3 having an ultrasonic transducer 2 for generating ultrasonic vibration, and
coagulation / disappearance of the affected area using the ultrasonic vibration. A handle unit 4 is
provided to perform an incision procedure.
[0023]
The handle unit 4 includes an operation portion 5, an insertion sheath portion 8 composed of a
long outer tube 7, and a distal end treatment portion 30.
The proximal end portion of the insertion sheath portion 8 is attached to the operation portion 5
so as to be rotatable around the axis.
[0024]
The distal end treatment unit 30 is provided at the distal end of the insertion sheath unit 8.
The operation unit 5 of the handle unit 4 includes an operation unit main body 9, a fixed handle
10, a movable handle 11, and a rotation knob 12.
The operation unit main body 9 is integrally formed with the fixed handle 10.
[0025]
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A slit 13 through which the movable handle 11 is inserted is formed on the back side of the
connecting portion between the operation portion main body 9 and the fixed handle 10.
The upper portion of the movable handle 11 extends inside the operation portion main body 9
through the slit 13.
[0026]
A handle stopper 14 is fixed to the lower end of the slit 13.
The movable handle 11 is rotatably attached to the operation unit main body 9 via a handle
support shaft 15.
The movable handle 11 is designed to be opened and closed with respect to the fixed handle 10
as the movable handle 11 pivots about the handle support shaft 15.
[0027]
A substantially U-shaped connecting arm 16 is provided at the upper end of the movable handle
11. Further, the insertion sheath portion 8 has an outer tube 7 and an operation pipe 17 axially
movably inserted into the outer tube 7.
[0028]
A large diameter portion 18 larger in diameter than the distal end portion is formed at the
proximal end portion of the sheath tube 7. The rotary knob 12 is mounted around the large
diameter portion 18.
[0029]
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A ring-shaped slider 20 is provided on the outer peripheral surface of the operation pipe 19 so as
to be movable along the axial direction. A fixing ring 22 is disposed behind the slider 20 via a
coil spring (elastic member) 21.
[0030]
Furthermore, the proximal end of the grip portion 23 is rotatably connected to the distal end of
the operation pipe 19 via an action pin. The grasping portion 23 constitutes a treatment portion
of the ultrasonic medical device 1 together with the distal end portion 31 of the probe 6. Then,
when the operation pipe 19 moves in the axial direction, the gripping portion 23 is pushed and
pulled in the front-rear direction via the action pin.
[0031]
At this time, when the operation pipe 19 is moved to the hand side, the grip 23 is pivoted
counterclockwise around the fulcrum pin via the action pin.
[0032]
As a result, the gripping portion 23 pivots in the direction in which the tip end portion 31 of the
probe 6 approaches (the closing direction).
At this time, the living tissue can be gripped between the one-sided grip type gripping portion 23
and the tip end portion 31 of the probe 6.
[0033]
With the living tissue thus held, power is supplied from the ultrasonic power source to the
ultrasonic transducer 2 to vibrate the ultrasonic transducer 2. This ultrasonic vibration is
transmitted to the tip 31 of the probe 6. Then, coagulation / dissection treatment of the living
tissue held between the holding portion 23 and the distal end portion 31 of the probe 6 is
performed using the ultrasonic vibration.
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[0034]
(Silver Unit) Here, the vibrator unit 3 will be described. As shown in FIG. 2, the transducer unit 3
integrally assembles the ultrasonic transducer 2 and a probe 6 which is a rod-like vibration
transmitting member for transmitting ultrasonic vibration generated by the ultrasonic transducer
2. It is
[0035]
In the ultrasonic transducer 2, a horn 32 for amplifying the amplitude of the ultrasonic
transducer is continuously provided. The horn 32 is formed of stainless steel, duralumin, or a
titanium alloy such as 64Ti (Ti-6Al-4V).
[0036]
The horn 32 is formed in a conical shape in which the outer diameter becomes smaller toward
the distal end side, and the outward flange 33 is formed on the proximal end outer peripheral
portion. Here, the shape of the horn 32 is not limited to the conical shape, but is an exponential
shape in which the outer diameter decreases exponentially as it goes to the tip side, or a step
shape that gradually narrows as it goes to the tip side. May be
[0037]
The probe 6 has a probe main body 34 formed of a titanium alloy such as 64Ti (Ti-6Al-4V). On
the proximal end side of the probe main body 34, the ultrasonic transducer 2 connected to the
above-described horn 32 is disposed.
[0038]
Thus, a transducer unit 3 in which the probe 6 and the ultrasonic transducer 2 are integrated is
formed. In the probe 6, the probe main body 34 and the horn 32 are screwed, and the probe
main body 34 and the horn 32 are joined.
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[0039]
The ultrasonic vibration generated by the ultrasonic transducer 2 is amplified by the horn 32 and
then transmitted to the tip 31 side of the probe 6. The distal end portion 31 of the probe 6 is
formed with a treatment portion described later for treating a living tissue.
[0040]
Further, on the outer peripheral surface of the probe main body 34, two rubber linings 35 are
attached at several points of the node position of vibration located halfway in the axial direction
at intervals formed in a ring shape by elastic members. The rubber lining 35 prevents contact
between the outer peripheral surface of the probe main body 34 and the operation pipe 19
described later.
[0041]
That is, at the time of assembly of the insertion sheath portion 8, the probe 6 as a transducerintegrated probe is inserted into the inside of the operation pipe 19. At this time, the rubber
lining 35 prevents contact between the outer peripheral surface of the probe main body 34 and
the operation pipe 19.
[0042]
In addition, the ultrasonic transducer 2 is electrically connected to a not-shown power supply
device main body that supplies a current for generating ultrasonic vibration via an electric cable
36. The ultrasonic transducer 2 is driven by supplying power from the power supply device main
body to the ultrasonic transducer 2 through the wiring in the electric cable 36.
[0043]
From the above description, the transducer unit 3 transmits the ultrasonic transducer 2
generating ultrasonic vibration, the horn 32 amplifying the ultrasonic vibration generated by the
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ultrasonic transducer 2 and the amplified ultrasonic vibration. A probe 6 is provided.
[0044]
(Ultrasonic Transducer) Here, the ultrasonic transducer 2 as a laminated type ultrasonic vibration
device of the present invention will be described below.
As shown in FIG. 3 and FIG. 4, the ultrasonic transducer 2 of the transducer unit 3 has the abovementioned horn 32 screwed and connected to the probe main body 34 which is one of the
vibration transfer members in order from the tip The rectangular-shaped (quadrangular prismshaped) laminated vibrator 41 continuously connected to the rear of the horn 32 and a cover 51
covering the laminated vibrator 41 from the base end of the horn 32 to the electric cable 36 It is
configured to have.
[0045]
Note that the cover 51 covering the laminated vibrator 41 is broken at the base end portion so as
to cover the wires 36a and 36b of the electric cable 36 electrically connected to the two FPCs
(flexible printed circuit boards) 47 and 48 as current-carrying members. There is a stop 52. The
current-carrying members are not limited to the FPCs 47 and 48, and may be simple metal wires.
[0046]
The laminated vibrator 41 is joined to a front mass 42 formed of a rectangular (square columnar)
metal block body connected to the horn 32 by screwing or the like on the front side, and a
rectangular (square columnar) metal on the rear side. It is joined to the back mass 43 which
consists of blocks.
[0047]
The front mass 42 and the back mass 43 need to be small in absorption of ultrasonic vibration
and strong in strength, and therefore, like the horn 32, are formed of duralumin.
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The front mass 42 and the back mass 43 may be stainless steel or a titanium alloy such as 64Ti
(Ti-6Al-4V).
[0048]
Further, the lengths of the front mass 42 and the back mass 43 are designed such that the
ultrasonic transducer 2 has a desired resonance frequency.
[0049]
Furthermore, the laminated vibrator 41 may have an insulating member between the front mass
42 and the back mass 43 which is insulating and difficult to damp the vibration.
As this insulating member, for example, an insulating plate formed of a ceramic material such as
alumina, silicon nitride or the like on a rectangular (square columnar) plate may be used.
[0050]
As described above, even if the multi-layered vibrator 41 is provided with the insulating member,
the ultrasonic medical apparatus 1 shown in FIG. And breakage due to high frequency from the
treatment tool is prevented.
[0051]
The laminated vibrator 41 uses a piezoelectric element formed of a lead-free single crystal
material having a high Curie point, and a plurality of piezoelectric single crystals 61 as a
piezoelectric single crystal chip, which is this piezoelectric element, are stacked in this case. It is
arranged.
[0052]
Between the four piezoelectric single crystals 61, the front mass 42 and the back mass 43, a
positive electrode layer is formed as a bonding metal layer formed of a lead-free solder, which
will be described later, as a brazing material. The electric bonding metal 62 and the negative
bonding metal 63 to be a negative electrode layer are alternately interposed.
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[0053]
The laminated vibrator 41 is not limited to the positive side bonding metal 62 or the negative
side bonding metal 63 provided between the piezoelectric single crystal 61 and between the
piezoelectric single crystal 61 and the front mass 42 or the back mass 43. The electrical contact
portions of the FPCs 47 and 48 are electrically connected by solder, conductive paste or the like.
[0054]
(Method of Manufacturing Ultrasonic Transducer) Next, a method of manufacturing the
ultrasonic transducer 2 described above will be described in detail below.
First, the ultrasonic transducer 2 uses a piezoelectric material having a high Curie temperature
(Curie point) and whose piezoelectric characteristics do not deteriorate even at the melting point
of a bonding metal. Here, a piezoelectric material made of lithium niobate (LiNbO3) as a single
crystal material It is made from a single crystal wafer 71 (see FIG. 5).
[0055]
The piezoelectric single crystal wafer 71 has a crystal orientation called a 36-degree rotation Ycut so as to increase the electromechanical coupling coefficient in the thickness direction of the
piezoelectric element.
[0056]
First, as shown in FIGS. 5 and 6, base metal 72 is formed on the front and back surfaces of
piezoelectric single crystal wafer 71.
Specifically, the piezoelectric single crystal wafer 71 has good adhesion and wettability with leadfree solder on the front and back surfaces, for example, Ti / Ni / Au, Ti / Pt / Au, Cr / Ni / Au or
An underlying metal 72 composed of Cr / Ni / Pd / Au is deposited by vapor deposition,
sputtering, plating or the like.
Next, as shown in FIGS. 7 and 8, the piezoelectric single crystal body 61 as a piezoelectric chip is
cut out into a rectangular shape from the piezoelectric single crystal wafer 71 on which the base
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metal 72 is formed.
Specifically, the piezoelectric single crystal wafer 71 is cut out along a dashed line (virtual line)
shown in FIG. 7 by a thin dicing blade, and a piezoelectric single chip as a rectangular
piezoelectric chip as shown in FIG. A plurality of crystals 61 are extracted.
With such a configuration, the plurality of piezoelectric single crystals 61 can be manufactured
inexpensively.
[0057]
Next, as shown in FIG. 9, the number of sheets according to the specification of the desired
ultrasonic transducer 2, here four piezoelectric single crystals 61, is stacked, and a laminate
comprising these four piezoelectric single crystals 61 is provided. The front mass 42 and the
back mass 43 which are mass members are joined so as to sandwich the both ends of the
laminated vibrator 41. Specifically, a first brazing material 73, which is a non-lead solder, is
provided as a first bonding material between the base metals 72 of the four piezoelectric single
crystals 61.
[0058]
The three first brazing materials 73 interposed between the four piezoelectric single crystal
bodies 61 are set to the minimum thickness d1 necessary for joining the piezoelectric single
crystal bodies 61 which are the same material. The first brazing material 73 is disposed on one
of the base metals 72 of the piezoelectric single crystal wafer 71 by screen printing or ribbon
form (solder pellet).
[0059]
Further, the front mass 42 and the back mass 43, which are metal blocks, are joined so that both
ends of the laminated vibrator 41 in which the four piezoelectric single crystals 61 and the three
first brazing materials 73 are laminated are sandwiched.
[0060]
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Here, a second brazing material 76, which is a non-lead solder as a second bonding material, is
provided between the piezoelectric single crystal 61 and the front mass 42 and the back mass 43
located at both ends.
[0061]
The second brazing filler metal 76 interposed between the piezoelectric single crystal 61, which
is a dissimilar material, and the front mass 42 or the back mass 43, has a thickness d1 of the first
brazing filler metal 73, as shown in FIG. The thick thickness d2 is also set.
[0062]
In the same manner as the first brazing filler metal 73, the second brazing filler metal 76 is
screen-printed or ribbon-shaped (solder pellet) on the base metal 72 of the piezoelectric single
crystal 61 or on one surface of the front mass 42 and back mass 43. It is arranged by
[0063]
Then, the four piezoelectric single crystals 61, the front mass 42 and the back mass 43 are
heated to a temperature at which the first brazing filler metal 73 and the second brazing filler
metal 76 joining each other melt and are slowly cooled.
Thus, the four piezoelectric single crystals 61, the front mass 42 and the back mass 43 are joined
to each other by the first brazing material 73 and the second brazing material 76 in the
laminated state.
[0064]
In the heating step of bonding the four piezoelectric single crystals 61, the front mass 42 and the
back mass 43, pressure may be applied so as to be compressed in the stacking direction as
necessary.
[0065]
Thus, the ultrasonic transducer 2 in which the four piezoelectric single crystals 61, the front
mass 42 and the back mass 43 are stacked and joined by the first brazing material 73 or the
second brazing material 76 is completed.
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[0066]
The ultrasonic vibrator 2 manufactured in this manner includes the base metal 72 formed on the
four piezoelectric single crystals 61, and the positive power side junction is formed by the first
brazing material 73 and the second brazing material 76. The metal 62 or the negative electrode
side bonding metal 63 is configured.
[0067]
In the center of one end face of the front mass 42, a tapped screw hole 42a is machined.
The horn 32 and the front mass 42 are screwed together by screwing the screw portion 32a
integrally formed with the horn 32 in the screw hole 42a.
[0068]
Then, as shown in FIG. 11 and FIG. 12, two FPCs 47 and 48 as current-carrying members are
mounted on the ultrasonic transducer 2.
Specifically, the positive side bonding metal 62 and the negative side bonding metal 63 of the
ultrasonic transducer 2 are formed by using the electrical contacts of the FPCs 47 and 48, the
solder, the conductive paste, etc. It is electrically connected through.
[0069]
That is, in order to electrically connect the positive side bonding metal 62 and the negative side
bonding metal 63 to the FPCs 47, 48, the electrical properties of the FPCs 47, 48 on the outer
surfaces of the positive side bonding metal 62 and the negative side bonding metal 63 The
contact points are in contact via the electrical connection 49, and the FPCs 47 and 48 are fixed
to the laminated vibrator 41.
[0070]
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In this manner, the electrical connection between the positive and negative bonding metals 62
and 63 and the FPCs 47 and 48 is established.
And wiring 36a, 36b (refer FIG. 3 and FIG. 4) of the above-mentioned electric cable 36 is
connected to FPC47 and 48.
[0071]
Although the horn 32 and the front mass 42 are screwed in FIGS. 10 to 12, the ultrasonic
vibrator 2 is not connected to the horn 32 and the front mass 42 by screwing. It may be
performed either before or after the mounting of the FPCs 47 and 48.
[0072]
With such a configuration, the wiring 36a of the electric cable 36, the FPC 47, the electrical
connection portion 49, and the positive electrode side metal 62 are electrically connected on the
positive electrode side.
Further, as the negative electrode side, the wiring 36 b of the electric cable 36, the FPC 48, the
electrical connection portion 49, and the negative electrode metal 63 are electrically connected.
By these electrical connections, a drive signal is applied to the four piezoelectric single crystals
61 via the positive side bonding metal 62 and is returned from the negative side bonding metal
63.
[0073]
Note that the exposed surface portions of the positive side bonding metal 62, the negative side
bonding metal 63, and the electrical connection portion 49 may be covered with an insulator
such as a resin to prevent the occurrence of unnecessary electrical connection which becomes
defective. In order to reinforce the mechanical fixing of the FPCs 47 and 48, the FPCs 47 and 48
may be fixed to the positive side bonding metal 62 and the negative side bonding metal 63 with
an adhesive.
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Furthermore, the FPCs 47 and 48 may be fixed to the surfaces of the side portions of the four
piezoelectric single crystal bodies 61 with an adhesive.
[0074]
According to the manufacturing process of the ultrasonic transducer 2 described above, the front
mass 42, the four piezoelectric single crystals 61 and the back mass 43 are sequentially joined
from the tip to the bonding metal layer and the positive metal bonding metal 62 and the negative
metal bonding metal. The first braze material 73 and the second braze material 76, which are 63,
are integrated by joining, and from the FPCs 47 and 48 provided on the side surfaces of this
laminate, the positive-side joining metal 62 via the electrical connection 49. The entire ultrasonic
transducer 2 is made to ultrasonically vibrate by applying a drive signal thereto and returning it
by means of the negative electrode side bonding metal 63.
[0075]
By the way, in the above-mentioned ultrasonic vibrator 2, since the location where the
piezoelectric single crystal bodies 61 of the laminated oscillator 41 are joined is the same
material, in this case, lithium niobate (LiNbO3), they are joined and driven. The thermal stress
generated in the four piezoelectric single crystals 61 due to the temperature change of is small.
[0076]
On the other hand, since the junction between the piezoelectric single crystal 61, the front mass
42 and the back mass 43 is a junction of different materials, the thermal expansion coefficient (8
to 15 here) of two different materials, here lithium niobate (LiNbO3) From the difference
between × 10 <−6> [1 / ° C]) and the thermal expansion coefficient of duralmin (24 × 10
<−6> [1 / ° C]), the front mass 42 by temperature change during bonding and driving
Alternatively, the two piezoelectric single crystals 61 at both ends joined to the back mass 43
generate a larger thermal stress than the homogeneous material joint.
[0077]
Therefore, large thermal stress is generated in the two piezoelectric single crystals 61 at both
ends joined to the front mass 42 or the back mass 43, and the internal stress is generated with
the increase of the internal force, and the crack is generated.
[0078]
Further, the first brazing filler metal 73 and the second brazing filler metal 76 constituting the
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positive side joining metal 62 or the negative side joining metal 63 are more Younger than the
piezoelectric single crystal 61, the front mass 42 and the back mass 43. It is a soft material with
a small modulus (elastic constant).
[0079]
Therefore, although the first brazing filler metal 73 or the second brazing filler metal 76 has the
function of absorbing the thermal stress generated in the piezoelectric single crystal body 61, the
absorption of the ultrasonic wave generated in the ultrasonic transducer 2 also increases. .
[0080]
Therefore, if the thickness of the first brazing filler metal 73 and the second brazing filler metal
76 is too thick, the characteristics of the ultrasonic transducer 2 as the Langevin transducer
deteriorate.
[0081]
In order to prevent this, the ultrasonic vibrator 2 according to the present embodiment has a
thickness of the first brazing material 73 as a homogeneous material joint for joining between
four piezoelectric single crystals 61 which are homogeneous materials. The thickness d2 of the
second brazing material 76 as a dissimilar-material joint where a relatively large thermal stress is
generated with a minimum thickness d1 necessary for joining four piezoelectric single crystals
61, as the first brazing material The thickness of the material 73 is larger than the thickness d1
(d1 <d2) so that thermal stress during the heating step and during driving can not be transmitted
to the two piezoelectric single crystals 61 at both ends.
[0082]
In other words, the second brazing filler metal 76 has a smaller Young's modulus (elastic
constant) than the piezoelectric single crystal 61, the front mass 42 and the back mass 43 and is
soft.
Therefore, in the ultrasonic transducer 2, the second brazing material 76 is thickened to act as a
stress relaxation layer for joining the piezoelectric single crystal 61, which is a dissimilar material
joining portion, and the front mass 42 or the back mass 43. ing.
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[0083]
The stress relieving layer preferably has a large thickness. However, the stress relieving layer has
a greater thickness than the piezoelectric single crystal body 61 made of duralumin and lithium
niobate (LiNbO3) used for the front mass 42 and the back mass 43. The loss of the ultrasonic
waves generated by the acoustic transducer 2 increases.
[0084]
Therefore, it is desirable that the volumes of the first brazing filler metal 73 and the second
brazing filler metal 76 be as small as possible.
That is, the smaller the volume of the first brazing filler metal 73 and the second brazing filler
metal 76, the smaller the loss of the generated ultrasonic waves as the characteristic of the entire
ultrasonic transducer 2.
[0085]
Therefore, the ultrasonic vibrator 2 according to the present embodiment uses the first brazing
material 73 having the minimum thickness d1 necessary for the joint between the four
piezoelectric single crystals 61 which hardly generate thermal stress. Between the two
piezoelectric single crystals 61 and the front mass 42 or the back mass 43 provided at both ends
where thermal performance deterioration (reduction of the Q value) is prevented and thermal
stress due to the thermal expansion coefficient difference is significantly generated. In this case,
by using the second brazing material 76 having a thickness d2 thicker than the first brazing
material 73, the thermal stress is reduced, and cracking of the two piezoelectric single crystals
61 provided in the dissimilar material joint portion To reduce the
[0086]
Thereby, the ultrasonic transducer 2 degrades the performance of the entire ultrasonic
transducer 2 while preventing the cracking of the two piezoelectric single crystals 61 provided at
both ends joined to the front mass 42 or the back mass 43. Can be prevented.
[0087]
The thermal expansion coefficients of the first brazing filler metal 73 and the second brazing
filler metal 76 are the thermal expansion coefficients of the piezoelectric single crystal 61 (8 to
15 ×) in order to reduce the thermal stress generated in the piezoelectric single crystal 61. It is
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desirable to use a bonding metal between 10 <−6> [1 / ° C.]) and the thermal expansion
coefficient (24 × 10 <−6> [1 / ° C.]) of the front mass 42 and the back mass 43 .
[0088]
The first brazing filler metal 73 and the second brazing filler metal 76 have thermal expansion
coefficients, for example, between the thermal expansion coefficients of the lithium niobate
(LiNbO3) piezoelectric single crystal 61, the duralumin front mass 42 and the back mass 43.
Sn̶Ag̶Cu based solder is used.
[0089]
The thermal expansion coefficient of the Sn̶Ag̶Cu-based solder used for the first brazing filler
metal 73 and the second brazing filler metal 76 is that of lithium niobate (LiNbO 3) (8-15 × 10
<−6> [1] It is 21 × 10 <−6> [1 / ° C.] which is larger than / ° C.] and smaller than the
thermal expansion coefficient (24 × 10 <−6> [1 / ° C.]) of duralumin.
[0090]
Thereby, in particular, the second brazing material 76 of the Sn̶Ag̶Cu solder, which is a
bonding material of the two piezoelectric single crystals 61 provided at both ends, and the front
mass 42 and the back mass 43, Serves to absorb the difference between the thermal expansion
coefficients of the two piezoelectric single crystals 61, the front mass 42 and the back mass 43
provided on the substrate, and the stress on the piezoelectric single crystals 61 is reduced. The
occurrence of cracking is prevented.
[0091]
The second brazing filler metal 76 only needs to have a thermal expansion coefficient between
the thermal expansion coefficients of lithium niobate (LiNbO3) and duralumin, and in addition to
the Su-Ag-Cu solder, for example, Sn Based solder, Sn-Ag solder or Sn-Cu solder may be used.
[0092]
Further, the thermal stress generated by the difference between the thermal expansion
coefficients of the front mass 42 and the back mass 43 in the piezoelectric single crystal 61 is
shown by a curve as shown in FIG. 13 according to the thickness of the second brazing material
76. Occurs on
[0093]
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P1 on the curve of FIG. 13 indicates that the piezoelectric single crystal 61 is broken due to the
thermal stress σ1 generated due to the difference in thermal expansion coefficient between the
front mass 42 and the back mass 43.
[0094]
Here, the thickness d2 of the second brazing filler metal 76 which is a bonding metal is a
piezoelectric single crystal 61 in which a predetermined safety factor (for example, a half of the
thermal stress σ1) is considered based on P1 as shown in P2. From the thickness d2 min which
is not cracked even if the thermal stress .sigma.2 occurs, the thickness d2max at which the
thermal stress .sigma.3 generated in the piezoelectric single crystal 61 hardly changes even if the
thickness of the brazing material 76 shown in P3 is changed. Set to
[0095]
As shown in FIG. 13, even if the thickness d 2 of the second brazing material 76 exceeds the
thickness d 2 max, it is generated in the piezoelectric single crystal 61 due to the difference in
thermal expansion coefficient between the front mass 42 and the back mass 43. Since the
thermal stress σ3 does not change, if the thickness is larger than d2max, the performance of the
ultrasonic transducer 2 is further degraded.
[0096]
Therefore, the thickness d2 of the second brazing material 76 is most preferably the thickness
d2max if the loss of the ultrasonic waves generated by the ultrasonic transducer 2 is within the
allowable range of the specification.
That is, the upper limit of the thickness d2 of the second brazing filler metal 76 is the thinnest
thickness d2max at which the thermal stress σ3 generated in the piezoelectric single crystal 61
does not change.
[0097]
Furthermore, in order to increase the thickness d2 of the second brazing filler metal 76 with
respect to the thickness d1 of the first brazing filler metal 73, it is sufficient to set the thickness
by screen printing or increase the thickness of the solder pellet prepared in advance. Therefore,
the inexpensive ultrasonic transducer 2 can be realized without changing the extra steps,
processes and the like.
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[0098]
In the case of using a ribbon form (solder pellet) for the first brazing material 73 and the second
brazing material 76, for example, as shown in FIG. If the second brazing filler metal 76 is formed,
it is not necessary to prepare different thicknesses.
That is, by setting the thickness d2 of the second brazing material 76 to be an integral multiple
of the first brazing material 73, the cost becomes lower.
[0099]
Moreover, although the example of the shape which can be manufactured most cheaply in the
rectangular block shape was mentioned as the ultrasonic transducer 2 in the above-mentioned, it
is not limited to this, For example, the shape of these members made cylindrical shape May be.
[0100]
As described above, the ultrasonic transducer 2 which is the layered ultrasonic vibration device
of the present embodiment and the ultrasonic medical device 1 having the ultrasonic transducer
2 can be manufactured at low cost, and can be used as a mass material. The piezoelectric body
can be prevented from breakage or the like due to the stress caused by the difference between
the thermal expansion coefficients of the metal block and the piezoelectric body.
[0101]
The invention described in the above-described embodiment is not limited to the embodiment
and the modifications, and in the implementation stage, various modifications can be made
without departing from the scope of the invention.
Furthermore, the above embodiments include inventions of various stages, and various
inventions can be extracted by appropriate combinations of a plurality of disclosed configuration
requirements.
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[0102]
For example, even if some of the configuration requirements are removed from all the
configuration requirements shown in the embodiment, the configuration requirements can be
eliminated if the problems described can be solved and the described advantages can be
obtained. The configuration can be extracted as the invention.
[0103]
Reference Signs List 1 ultrasonic medical device 2 ultrasonic transducer 3 transducer unit 4
handle unit 5 operation unit 6 probe 7 outer sheath tube 8 insertion sheath portion 9 operation
unit main body 10 fixed handle 11 movable handle 12: rotation knob 13: slit 14: handle stopper
15: handle support shaft 16: connection arm 17: operation pipe 18: large diameter portion 19:
operation pipe 20: slider 22: fixing ring 23: grip portion 30: tip treatment portion 31 ... Tip
portion 32 ... Horn 32a ... Threaded portion 33 ... Outgoing flange 34 ... Probe main body 35 ...
Rubber lining 36 ... Electric cable 36a, 36b ... Wiring 41 ... Laminated vibrator 42 ... Front mass
42a ... Screw hole 43 ... Back mass 49 ... Electrical connection portion 51: Cover body 52:
Stabilization 61: Piezoelectric single crystal body 62: Positive side bonding metal 63: Negative
Electrically bonded metal 71: Piezoelectric single crystal wafer 72: Base metal 73: first brazing
material 76: second brazing material
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