JPH10308994A - Manufacture of ultrasonic wave oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce dispersion in an ultrasonic wave characteristic by reducing dispersion in a curvature of a recessed face formed to a composite piezoelectric body. SOLUTION: In the case of assembling a ultrasonic wave oscillator, a cylindrical member consisting of an insulation layer 9 and a metal housing 10 is fitted to an outer circumferential part of a recessed part 7; after one end of the cylindrical member is pressed into contact with a butt section 7b, a composite piezoelectric body 1 is placed on a recessed SR face 7a of the recessed part 7; after a resin material used to form a matching layer 13 is coated in sufficient quantity ont an upper part of the composite piezoelectric body 1, a projection 6 is pressed onto the resin to allow the projection 6 and the recessed part 7 to have the resin inbetween thereby forming the composite piezoelectric body 1 to be a recessed face, and the matching layer 13 is formed to the upper part. After curing the matching layer 13, the recessed part 7 is removed, an ultrasonic wave absorbing body is filled in the inside of the insulation layer 9 toward a rear electrode of the composite piezoelectric body 1 while the projection 6 is fitted and then the projection 6 is removed to form subassembly of the ultrasonic wave oscillator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an ultrasonic transducer used for an ultrasonic diagnostic apparatus or the like.

[0002]

2. Description of the Related Art In the medical field, an ultrasonic pulse is repeatedly transmitted from an ultrasonic transducer into a living tissue, and an echo of the ultrasonic pulse reflected from the living tissue is provided on the same or separate body. An ultrasound diagnostic apparatus that displays information collected from a plurality of directions in a living body as a visible ultrasound tomographic image by gradually shifting the direction in which the ultrasound pulse is transmitted and received by the More various proposals have been made.

As an ultrasonic transducer used in such an ultrasonic diagnostic apparatus, for example, Japanese Unexamined Patent Publication No. 60-85700
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, there is a device in which a vibrator is configured using a composite piezoelectric body having a structure in which a resin is filled in a gap between a plurality of columnar piezoelectric bodies arranged at an interval from each other. Ultrasonic transducers using composite piezoelectric materials have low acoustic impedance and good matching with living tissue, and have flexibility so that they can be easily deformed and form a concave surface with a desired radius of curvature. The feature is that the acoustic lens can be omitted.

[0004]

When assembling an ultrasonic vibrator using a composite piezoelectric body, the conventional assembling procedure involves placing the composite piezoelectric body on a surface of a curved ultrasonic absorber. The composite piezoelectric body is formed into a concave shape by pressing the composite piezoelectric body with a curved mold and bonding the ultrasonic absorber to the composite piezoelectric body. For this reason, in the conventional manufacturing method, when forming the composite piezoelectric body in a concave shape, the processing accuracy of the curved surface of the ultrasonic absorber is not sufficient, and the curvature of the composite piezoelectric body varies, Variations in the thickness of the adhesive layer between the absorber and the absorber may cause variations in the ultrasonic characteristics, which may hinder the performance of the ultrasonic vibrator.

The present invention has been made in view of the above circumstances, and in an ultrasonic vibrator using a composite piezoelectric material, it is possible to suppress variations in the curvature of a concave surface and reduce variations in ultrasonic characteristics. It is an object of the present invention to provide a method for manufacturing a sound transducer.

[0006]

According to a method of manufacturing an ultrasonic transducer according to the present invention, a step of inserting a first mold having a concave surface having a desired radius of curvature into a hollow portion of a cylindrical holding table is inserted. When,
Placing a composite piezoelectric body composed of a plurality of columnar piezoelectric bodies and a resin filled between the piezoelectric bodies on the concave surface of the first mold; and forming a matching layer on the composite piezoelectric body and the holding table. A second mold having a convex surface having a radius of curvature obtained by applying a material, and subtracting a value obtained by adding a value obtained by adding a thickness of the composite piezoelectric body and a thickness of the matching layer from a radius of curvature of the concave surface of the first mold. hand,
Pressing the composite piezoelectric body at a predetermined pressure through the matching layer forming material, curing the matching layer forming material to form a matching layer, and removing the first mold,
Casting an ultrasonic absorber in the hollow portion of the holding table.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 relate to a first embodiment of the present invention, and FIG. 1 is a plan view showing a configuration of a composite piezoelectric body.
FIG. 2 is a cross-sectional view showing a configuration of a mold for forming a concave surface having a predetermined spherical curvature radius on the composite piezoelectric body. FIG. 3 shows a state when a matching layer laminated on the composite piezoelectric body is formed using the mold of FIG. FIG. 4 is a cross-sectional view showing a configuration of an ultrasonic vibrator in a state where an ultrasonic absorber is provided on the back surface of a composite piezoelectric body. FIG. 5 is a perspective view showing an external configuration of the ultrasonic vibrator of FIG. It is.

The first embodiment shows a configuration example of a circular ultrasonic transducer used for a mechanical scanning type ultrasonic probe.

In this embodiment, an ultrasonic vibrator is formed by using a disk-shaped composite piezoelectric body 1 as shown in FIG. In the composite piezoelectric body 1, a plurality of columnar piezoelectric bodies 2 are arranged at intervals from each other in the vertical and horizontal directions, and a gap between the columnar piezoelectric bodies 2 is filled with a flexible filling resin 3 made of urethane resin, silicon resin or the like. It is configured. The columnar piezoelectric body 2 is made of PZT
(Lead zirconate titanate), lead titanate, or the like, and the front surface electrode 4 and the back surface electrode 5 are formed by baking or vapor-depositing silver or gold on both surfaces of the composite piezoelectric body 1.
Are formed.

FIG. 2 shows a configuration of a convex type and a concave type in which the composite piezoelectric body 1 is formed to form a concave surface having a predetermined spherical curvature radius (hereinafter, referred to as SR). The convex 6 has a predetermined S
It has a convex SR surface 6a having an R, and a stepped portion 6b formed in a step shape is provided on an outer peripheral portion of the convex SR surface 6a. The concave mold 7 has a concave SR surface 7a corresponding to the convex SR surface 6a, and a stepped abutting portion 7b is provided on the outer peripheral portion of the base end of the concave mold 7. A signal line insertion hole 7c is provided through the center of the concave mold 7.

A procedure for assembling the ultrasonic transducer according to the present embodiment will be described with reference to FIG. First, a cylindrical member formed by bonding a metal housing 10 to the outer periphery of a cylindrical resin insulating layer 9 in advance is inserted into the outer peripheral portion of the concave mold 7, and one end of this cylindrical member is inserted into the abutting portion 7b. Abut.

Then, with one end of the signal line 11 electrically connected to the center of the back electrode 5 of the composite piezoelectric body 1 by soldering or a conductive adhesive, the signal line 11 is inserted into the signal line insertion hole 7 c of the concave mold 7. The composite piezoelectric body 1 is inserted through the concave SR
It is placed on the surface 7a. Then, one end of the ground wire 12 is electrically connected to the peripheral edge of the surface electrode 4 of the composite piezoelectric body 1 by soldering or a conductive adhesive.

Next, a resin material such as an epoxy resin constituting the matching layer 13 is applied to the upper portion of the composite piezoelectric body 1 and laid thereon, and then the convex mold 6 is pressed from above to press the convex mold 6 and the concave mold 7. Then, as shown in FIG. 3, the composite piezoelectric body 1 is formed into a concave shape, and the matching layer 13 is formed thereon. At this time,
The connecting portion of the ground line 12 is accommodated in a space formed between the stepped portion 6b of the convex die 6 and the concave die 7, and the matching layer 13 is formed. After the matching layer 13 has hardened, the concave mold 7 is removed.

Thereafter, the composite piezoelectric body 1 is turned upside down with the convex 6 attached, and an ultrasonic absorber made of epoxy resin or the like containing tungsten powder is placed inside the insulating layer 9 on the back electrode 5 side. After filling, the convex mold 6 is removed, and the other end of the ground wire 12 is electrically connected to the side surface of the housing 10 by soldering or a conductive adhesive, so that the ultrasonic wave as shown in FIGS. Form a set of transducers.

Although the subsequent steps are not shown, the other end of the signal line 11 is electrically connected to the signal line of the signal cable, and the shield line of the signal cable is electrically connected to the housing 10, so that the ultrasonic probe Is composed.

The materials of the convex mold 6 and the concave mold 7 are as follows.
A material having good releasability from the matching layer 13, for example, PTFE
(Polytetrafluoroethylene), or a metal. When the convex 6 and the concave 7 are made of metal, a release material is applied to the surface of the convex 6 and the matching layer 13 is formed.
You may make it improve the peeling property of the convex part 6 and the.

According to this embodiment, the concave SR surface 7 of the concave mold 7
Since the curvature of the composite piezoelectric body 1 is regulated by a, the shape of the concave surface of the composite piezoelectric body 1 depends only on the dimensional accuracy of the concave mold 7, so that the desired curvature can be easily formed on the composite piezoelectric body 1. Thus, the composite piezoelectric body 1 is not distorted during assembly, and the dimensional accuracy can be improved by suppressing the variation in the curvature of the concave surface of the composite piezoelectric body 1.

Further, since the ultrasonic absorber 14 is formed by casting after the composite piezoelectric body 1 is formed into a concave shape, the ultrasonic absorber 14 is not formed between the composite piezoelectric body 1 and the adhesive. Is provided, and the variation in the ultrasonic characteristics can be reduced without being affected by the thickness of the adhesive layer.

6 to 10 relate to a second embodiment of the present invention. FIG. 6 is a perspective view showing a configuration in which a flexible printed circuit board is connected to a composite piezoelectric body. FIG. FIG. 8 is a perspective view showing a configuration of a mold for forming a concave surface having a surface curvature radius. FIG. 8 is a perspective view showing a configuration of a part of an ultrasonic transducer using a composite piezoelectric body after a matching layer is formed. FIG. 10 is a perspective view showing a configuration of the ultrasonic transducer in a state where the ultrasonic transducer is divided into elements, and FIG. 10 is a cross-sectional view of the ultrasonic transducer in FIG.

The second embodiment shows an example of the configuration of an ultrasonic transducer in which a plurality of elements used for an electronic scanning ultrasonic probe are arranged in rows.

In this embodiment, an ultrasonic vibrator is formed by using a rectangular plate-shaped composite piezoelectric body 21 as shown in FIG.
The composite piezoelectric body 21 has a structure in which a plurality of columnar piezoelectric bodies are arranged as in the first embodiment, but a gap is filled with a flexible filler resin, and electrodes are formed on the front and rear surfaces by vapor deposition, baking, or the like. Have been. A flexible printed circuit board 22 is connected to the back electrode side of the composite piezoelectric body 21, and the signal pattern 23 of the flexible printed circuit board 22 and the back electrode are electrically connected by soldering or anisotropic conductive adhesive or the like. At the end of the flexible printed circuit board 22,
A land 24 for connecting a signal cable or connector to the signal pattern 23 is provided.

FIG. 7 shows a configuration of a convex type and a concave type in which a concave surface having a predetermined cylindrical surface radius of curvature (hereinafter, referred to as CR) is formed by molding the composite piezoelectric body 21 and a housing provided therebetween. is there. The convex mold 26 is a convex C having a predetermined CR.
It has an R surface 26a. The concave mold 27 has a convex C
A concave CR surface 27a corresponding to the R surface 26a;
Is provided with an abutting portion 27b formed in a step shape on the outer periphery of the base end. Further, a storage recess 27c for storing a connection portion between the composite piezoelectric body 21 and the flexible printed circuit board 22 is provided on one side of the concave CR surface 27a.

A rectangular cylindrical resin housing 28 is provided between the convex mold 26 and the concave mold 27 when the composite piezoelectric body 21 is formed into a concave shape. The housing 28 is provided with a convex portion 28a serving as a guide for bending the flexible printed circuit board 22 on one side, and a stepped portion 28b formed in a step shape on the other side.

A procedure for assembling the ultrasonic transducer according to the present embodiment will be described. First, on the outer periphery of the concave mold 27,
The housing 28 is inserted and one end is brought into contact with the abutting portion 27b. Then, the flexible printed circuit board 2 shown in FIG.
2 is connected to the composite piezoelectric body 21 with a concave CR
The flexible printed circuit board 22 is placed on the surface 27 a and bent along the convex portion 28 a of the housing 28.

Then, after a conductive resin material is applied to the upper portion of the composite piezoelectric body 21 and laid thereon, the convex mold 26 is pressed from above and sandwiched between the convex mold 26 and the concave mold 27, as shown in FIG. Thus, the composite piezoelectric body 21 is formed into a concave shape, and the matching layer 30 is formed thereon. At this time, the matching layer 30 on the side facing the flexible printed board 22 is formed up to the stepped portion 28 b of the housing 28. Matching layer 3
After 0 has hardened, the concave mold 27 is removed.

Thereafter, the ultrasonic absorber 3 made of epoxy resin or the like containing tungsten powder is placed inside the housing 28 on the back electrode side of the composite piezoelectric body 21 with the convex 26 attached.
After filling 1, the convex 26 is removed.

Next, as shown in FIG. 9, from the state of the assembly of the ultrasonic transducer formed as shown in FIG. 8, the surface of the matching layer 30 is cut at a predetermined pitch by a dicing saw or a laser as shown in FIG. By forming the dividing groove 32 by the step, the composite piezoelectric body 21 is divided to form a plurality of elements.

At this time, as shown in FIG.
Numeral 2 is provided to the depth where the composite piezoelectric body 21 is located to completely separate the composite piezoelectric body 21, while the matching layer 30 is not completely divided and the undivided portion 30 a is left. Also, the dividing groove 32
Is set so that only the resin portion is cut in accordance with the arrangement pitch of the columnar piezoelectric bodies of the composite piezoelectric body 21. In addition, in order to prevent the matching layer 30 and the composite piezoelectric body 21 from being separated when the composite piezoelectric body 21 is divided into a plurality of elements, in the present embodiment, the ultrasonic absorber 31 is provided on the back electrode side of the composite piezoelectric body 21. After filling, the dividing groove 32 is formed.

The composite piezoelectric body 21 has a portion on the back surface where the back electrode 34 is not formed so that the back electrode 34 does not conduct with the conductive matching layer 30. Then, the surface electrodes 33 are electrically connected to each other via the conductive matching layer 30 to form a ground line. In addition, when a material containing a metal powder such as tungsten is used as the ultrasonic absorber 31, the ultrasonic absorber 31 is made of resin in order to prevent short circuit between the back electrode 34 and the front electrode 33 because it has conductivity. Is completely electrically separated from the matching layer 30 by the housing 28.

According to the second embodiment, similarly to the first embodiment, the composite CR 2 is formed by the concave CR surface 27a of the concave mold 27.
1 is regulated, the composite piezoelectric body 21 can be easily formed with a desired curvature, and the composite piezoelectric body 2 can be easily formed.
The dimensional accuracy can be improved by suppressing the variation in the curvature of the concave surface. In addition, since the ultrasonic absorber 31 is cast and formed after the composite piezoelectric body 21 is formed into a concave shape, an adhesive layer is not interposed between the composite piezoelectric body 21 and the ultrasonic absorber 31. It is possible to eliminate the influence of the thickness of the adhesive layer and reduce the variation in the ultrasonic characteristics.

[Supplementary Notes] (1) A step of inserting a first mold having a concave surface having a desired radius of curvature into a hollow portion of a cylindrical holding table, and a plurality of columnar piezoelectric bodies and a space between the piezoelectric bodies. Placing a composite piezoelectric body composed of a resin filled in the first die on the concave surface of the first mold, applying a matching layer forming material on the composite piezoelectric body and the holding table, In the second mold having a convex surface having a radius of curvature obtained by subtracting the value obtained by adding the thickness of the composite piezoelectric body and the thickness of the matching layer from the radius of curvature of the concave surface of the mold, via the matching layer forming material Pressing the composite piezoelectric body with a predetermined pressure, curing the matching layer forming material to form a matching layer, and removing the first mold to absorb ultrasonic waves in a hollow portion of the holding table. Casting the body.

(2) The cylindrical holder is a hollow cylindrical member, the composite piezoelectric body is a disk, and the concave surface of the first mold is a spherical surface defined by a desired radius of curvature. And the convex surface of the second type is defined by a radius of curvature obtained by subtracting a value obtained by adding a thickness of the composite piezoelectric body and a thickness of the matching layer from a radius of curvature of the concave surface of the first type. 2. The method for manufacturing an ultrasonic transducer according to claim 1, wherein the method is a part of a spherical surface.

(3) The cylindrical holder is a hollow rectangular tube, the composite piezoelectric body is a rectangular plate, and the concave surface of the first mold is defined by a desired radius of curvature. The convex surface of the second mold is a part of a cylindrical surface, and the convex surface of the second mold is defined by a radius of curvature obtained by subtracting a value obtained by adding the thickness of the composite piezoelectric body and the thickness of the matching layer from the curvature radius of the concave surface of the first mold. 2. The method for manufacturing an ultrasonic transducer according to claim 1, wherein the method is a part of a cylindrical surface to be formed.

(4) connecting a plurality of conductors to a rectangular composite piezoelectric body composed of a plurality of columnar piezoelectric bodies and a resin filled between the piezoelectric bodies; ,
A step of inserting a first mold provided with a concave surface having a desired radius of curvature;
Placing on the concave surface of the mold, applying a matching layer forming material on the composite piezoelectric body and the holding table, and calculating the thickness of the composite piezoelectric body from the radius of curvature of the concave surface of the first mold. The composite piezoelectric body is pressed with a predetermined pressure via the matching layer forming material by a second mold having a convex surface having a radius of curvature obtained by subtracting a value obtained by adding the thickness of the matching layer, and the matching is performed. Curing the layer-forming material to form a matching layer; removing the first mold to cast and form an ultrasonic absorber in the hollow portion of the holding table; Forming a plurality of vibrating elements by dividing a layer, and electrically connecting the plurality of conductors and the plurality of vibrating elements independently of each other.

(5) The method of manufacturing an ultrasonic transducer according to appendix 4, wherein the matching layer forming material is a conductive resin.

(6) The plurality of conductors are provided on a flexible printed circuit board.
3. The method for producing an ultrasonic transducer according to claim 1.

(7) A cylindrical member holding portion capable of holding at least one cylindrical member of a cylindrical housing or an insulating layer, and an edge of the cylindrical member held by the cylindrical member holding portion. A first ultrasonic element forming die having a plate-like member holding portion capable of holding a plate-like piezoelectric body formed in a plate-like shape in the vicinity of the portion and having a concave portion in contact with the plate-like piezoelectric body. ,
A second ultrasonic element forming die having a convex portion corresponding to the concave portion formed in the plate-shaped member holding portion and having a pressing surface portion capable of pressing the plate-shaped piezoelectric body held in the plate-shaped member holding portion; An ultrasonic element forming apparatus comprising:

(8) The first ultrasonic element forming type includes:
8. The ultrasonic element forming apparatus according to claim 7, further comprising a signal line insertion portion through which a signal line connected to the plate-shaped piezoelectric body can be inserted.

(9) The second ultrasonic element forming type includes:
The ultrasonic element forming apparatus according to claim 7, further comprising a space at a peripheral portion of the pressing surface portion for securing a space between the plate-shaped piezoelectric body and the plate-shaped piezoelectric body when the plate-shaped piezoelectric body is pressed. .

[0040]

As described above, according to the present invention, in an ultrasonic vibrator using a composite piezoelectric body, there is an effect that variations in the curvature of the concave surface can be suppressed and variations in the ultrasonic characteristics can be reduced. .

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a composite piezoelectric body according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a mold for forming a concave surface having a predetermined spherical curvature radius on the composite piezoelectric body according to the first embodiment.

FIG. 3 is an explanatory view showing a state when a matching layer to be laminated on a composite piezoelectric body is formed using the mold of FIG. 2;

FIG. 4 is a cross-sectional view illustrating a configuration of an ultrasonic transducer in a state where an ultrasonic absorber is provided on the back surface of the composite piezoelectric body according to the first embodiment.

FIG. 5 is a perspective view showing an external configuration of the ultrasonic transducer shown in FIG. 4;

FIG. 6 is a perspective view showing a configuration in which a flexible printed board is connected to a composite piezoelectric body according to a second embodiment of the present invention.

FIG. 7 is a perspective view showing the configuration of a mold for forming a concave surface having a predetermined cylindrical surface curvature radius on the composite piezoelectric body according to the second embodiment.

FIG. 8 is a perspective view showing a configuration of a sub-unit of an ultrasonic transducer made of a composite piezoelectric body after a matching layer according to a second embodiment is formed.

FIG. 9 is a perspective view showing a configuration of an ultrasonic transducer in a state where the composite piezoelectric body according to the second embodiment is divided into a plurality of elements.

10 is a cross-sectional view of the ultrasonic transducer of FIG. 9 at an element division position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Composite piezoelectric material 4 ... Front surface electrode 5 ... Back surface electrode 6 ... Convex type 6a ... Convex SR surface 6b ... Stepped part 7 ... Concave type 7a ... Concave SR surface 7b ... Butting part 9 ... Insulating layer 10 ... Housing 11 ... Signal Line 12: Ground line 13: Matching layer 14: Ultrasonic absorber

Claims (1)

[Claims] A step of inserting a first mold having a concave surface having a desired radius of curvature into a hollow portion of a cylindrical holding table; and filling a plurality of columnar piezoelectric bodies and the space between the piezoelectric bodies. Placing a composite piezoelectric body made of resin on the concave surface of the first mold; applying a matching layer forming material on the composite piezoelectric body and the holding table; and concave surface of the first mold A second mold having a convex surface having a radius of curvature obtained by subtracting the value obtained by adding the thickness of the composite piezoelectric body and the thickness of the matching layer from the radius of curvature of the composite piezoelectric body via the matching layer forming material. Pressing a predetermined pressure and curing the matching layer forming material to form a matching layer; removing the first mold and casting an ultrasonic absorber in a hollow portion of the holding table. Forming the ultrasonic transducer.