JPH11164397A - Ultrasonic transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic transducer capable of easily and firmly drawing an electrode from a piezoelectric body. SOLUTION: A connecting member 11 is provided at an end part of a grounding electrode 61 of the piezoelectric body 1. Thickness of the connecting member 11 is determined as equal to or below the thickness of acoustic matching layers (matching layers 21 and 22). The electrode 12 is formed on the surface of the connecting member 11, the electrode 12 is electrically and physically connected with the grounding electrode 61 of the piezoelectric body 1 with conductive adhesive 13. In addition, one side of the connecting member 11 is positioned so that it comes to approximately the same surface as the side of the piezoelectric body 1. A driving electrode 62 of the piezoelectric body 1 is provided so that its end part is infiltrated from the back of the piezoelectric body 1 to the side. A rigid/flexible printed board is connected with the electrode 12 and the driving electrode 62 of the connecting member 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ultrasonic transducer used for an ultrasonic diagnostic apparatus, for example.

[0002]

2. Description of the Related Art In a conventional ultrasonic transducer, lead wires are drawn from a piezoelectric body made of, for example, piezoelectric ceramics using a flexible printed circuit (FPC) or the like. As a method of connecting the flexible printed board to the piezoelectric body, a method of soldering to the back surface of the piezoelectric body is used.

FIG. 1 is a sectional view in the slice direction showing such a conventional ultrasonic transducer. In the figure, 1 is, for example, a piezoelectric ceramic, 2 is an acoustic matching layer, 3
Denotes a backing material, 4 denotes a baked silver electrode, and 5 denotes a flexible printed circuit (FPC). At the edge in the slice direction, the baked silver electrode 4 on the back side of the piezoelectric ceramics 1 is a drive electrode, and the FPC 5 is connected thereto by soldering.

By the way, a composite piezoelectric body comprising a resin injected into a gap between columnar piezoelectric ceramics and electrodes arranged on the front surface (ultrasonic radiation surface) and the back surface (opposite to the ultrasonic radiation surface) is provided.
There is an ultrasonic transducer (composite piezoelectric transducer) of the type used as a piezoelectric plate. The composite piezoelectric body has a columnar and small shape, which increases the electroacoustic conversion efficiency of the piezoelectric body and increases the sensitivity of the transducer, and reduces the proportion of the piezoelectric ceramic in the piezoelectric body to reduce the acoustics of the piezoelectric plate. The main purpose is to improve the acoustic matching with the living body by reducing the impedance. The method of manufacturing this composite piezoelectric transducer is as follows: first, the piezoelectric ceramic is divided, the gap is filled with resin, a composite piezoelectric plate is formed, and then thin-film electrodes are formed on the front and back surfaces by vapor deposition and sputtering. There are known ways to do this.

A so-called array type transducer (composite piezoelectric array transducer) using a composite piezoelectric body is also known. As a method of manufacturing a composite piezoelectric array transducer, there are methods of forming electrodes (such as thin-film metal) divided into an array shape on a composite piezoelectric body and connecting an acoustic matching layer, a backing material, and the like, An electrode is formed on one side, an acoustic matching layer backing material is connected, and a drive electrode is pulled out from a plurality of arrays.
A method is known in which a PC board is connected and then divided into an array.

Here, the conventional ultrasonic transducer in which the FPC is connected to the back surface of the piezoelectric body has a relatively large connection area, facilitates the connection work, and has the same drawing direction of the signal electrode and the common electrode. This has the advantage of being effective in reducing noise, but has the following disadvantages. That is, there is a problem that a physical load is easily applied to a portion (particularly, a boundary portion) to which the signal extraction substrate is connected, and the vibrator is easily damaged. Another problem is that the radiation surface of the vibrator cannot be used effectively.

FIG. 2 is a cross-sectional view in the slice direction showing a conventional composite piezoelectric array transducer in which an electrode is formed on one surface of a composite piezoelectric body and then divided to form an array. At the edge in the slice direction,
After the FPC 5 is connected to the baked silver electrode 4 by soldering, it is divided in the depth direction in FIG.
(Forming a groove extending halfway), an array of composite piezoelectric bodies is formed.

A baked silver electrode 4 is formed on the back surface of the piezoelectric ceramic 1. Conventionally, various structures have been devised such as omitting the baked silver electrode 4. The common electrode 6 provided on the front surface (acoustic radiation surface) and the back surface of the composite piezoelectric body and electrically connecting the plurality of piezoelectric ceramics 1 and the resin 7 to each other is common. Electrodes are used as drive electrodes. As a method of extracting drive electrodes to a plurality of elements constituting an array, F
PC5 is used.

In such a conventional composite piezoelectric array transducer, the thin film electrodes formed on the front and back surfaces of the piezoelectric plate are insufficiently attached to the composite piezoelectric plate and the strength of the electrodes themselves is insufficient. When the array is divided, there is a problem in that the electrodes are peeled off from the surface of the composite piezoelectric plate, or the electrodes themselves are broken. Such electrode breaking failures include poor processability of the backing material and poor processability of the FPC,
Further, adverse conditions such as the presence of a structural discontinuity on the rear surface (because the FPC is connected to the rear surface) tend to occur on the rear surface side of the piezoelectric body, and also in the vicinity of the FPC connection portion. Defects tend to occur in a concentrated manner.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above circumstances, and has as its object to provide the following ultrasonic transducer. (1) An ultrasonic transducer capable of easily and firmly extracting an electrode from a piezoelectric body. (2) An ultrasonic transducer capable of reducing electrode breakage failure of a piezoelectric body in array division.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems and achieve the object, the present invention is configured as follows. (1) The ultrasonic transducer of the present invention has a first electrode on a predetermined surface of a piezoelectric body that converts an ultrasonic wave into an electric signal via an acoustic matching layer, and has a first electrode on a surface opposite to the first electrode. An ultrasonic transducer having a second electrode, comprising: a connecting member provided at an end of the piezoelectric body on the first electrode side, the connecting member having the same thickness as or less than the acoustic matching layer; Are drawn out in the lateral direction of the piezoelectric body via the connecting member, and the second electrode is drawn out in the same direction as this, and the lead-out portions of the first and second electrodes are made substantially coplanar. It is characterized by. (2) An ultrasonic transducer according to the present invention includes a composite piezoelectric body, a drive electrode for driving the composite piezoelectric body, and a flexible printed wiring board for leading the drive electrode.
Wherein the flexible printed wiring board is electrically connected at a front position of the composite piezoelectric body. (3) An ultrasonic transducer according to the present invention includes a composite piezoelectric body, and a drive electrode provided to extend from the back surface of the composite piezoelectric body to a part of the front surface via a side surface and to drive the composite piezoelectric body. A flexible printed wiring board connected to the drive electrode at a front surface position of the composite piezoelectric body, wherein an array of the composite piezoelectric body is formed after the flexible printed wiring board is connected to the drive electrode. It is characterized by being performed. (4) An ultrasonic transducer according to the present invention includes a composite piezoelectric body, a drive electrode for driving the composite piezoelectric body, and a flexible printed wiring board for leading out the drive electrode.
Wherein the flexible printed wiring board is electrically connected at a side position of the composite piezoelectric body. (5) An ultrasonic transducer according to the present invention includes: a composite piezoelectric body; and a drive electrode provided to extend from the back surface of the composite piezoelectric body to a part of the front surface via a side surface and to drive the composite piezoelectric body. A flexible printed wiring board connected to the drive electrode at a side surface position of the composite piezoelectric body, and the array formation of the composite piezoelectric body is performed after the connection of the flexible printed wiring board to the drive electrode. It is characterized by being performed. (6) An ultrasonic transducer of the present invention includes a composite piezoelectric body, a back electrode provided on the back of the composite piezoelectric body, and a back acoustic matching layer for protecting the back electrode.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 3 is a sectional view in the slice direction showing an ultrasonic transducer according to a first embodiment of the present invention.

Earth electrode (acoustic radiation surface side) 6 of piezoelectric body 1
At one end, a connection member (pad) 11 is provided. The thickness of the connection member 11 is determined by the acoustic matching layer (the matching layer 2).
It is desirable to make it equal to or less than 1 and 22). Thus, the connection member 11 does not hinder the formation of the acoustic matching layer or the addition of the acoustic lens. Connection member 11
An electrode 12 is formed on the surface of the piezoelectric element 1. The electrode 12 is electrically and physically connected to the ground electrode 61 of the piezoelectric body 1 via a conductive adhesive 13. Connection member 11
Is aligned so that one side surface is substantially flush with the side surface of the piezoelectric body 1.

The drive electrode 62 of the piezoelectric body 1 is provided such that its end goes from the back surface to the side surface of the piezoelectric body 1, and the drive electrode 62 is connected to the ground electrode 61 and the connection member 11 by the insulator 14. Is insulated with respect to the electrode 12.

In the present embodiment, a rigid / flexible printed circuit board is connected to the electrode 12 of the connecting member 11 and the drive electrode 62. The rigid / flexible printed circuit board includes a signal board S in which signal lines are arranged on a relatively soft and freely bendable base material, and a connection portion C made of a relatively hard and heat-resistant base material (for example, ceramic). Composed of A drive electrode lead-out lead and a ground electrode lead-out lead are provided in a connection area of the connection portion C. The connection area is provided with respect to the drive electrode 62 and the electrode 12 of the piezoelectric body 1 (conductive to the ground electrode 61). Solder 15
And can be connected on the same plane. Solder 1
Reference numeral 5 is applied to at least one of the connection areas before the step of joining the piezoelectric body and the rigid / flexible printed circuit board. The signal line of the rigid / flexible printed circuit board is formed in a single line at the connection portion C, and is cut into individual signal lines in a piezoelectric material dividing step related to array formation. Naturally, all ground wires are common.

According to the present embodiment configured as described above, the following operational effects can be obtained. That is, the connection member 11 having the same thickness as or less than the acoustic matching layer is provided at the end of the piezoelectric body 1, and the electrode 12 of the connection member 11 is electrically connected to the ground electrode 61. Further, the drive electrode 62 of the piezoelectric body 1 is provided such that its end goes from the back surface to the side surface of the piezoelectric body 1. Thus, the ground electrode 61 and the drive electrode 62 can be easily and firmly pulled out on the same side surface of the piezoelectric body 1. In this case, the physical load applied to the piezoelectric body 1 in connection with the signal board is also reduced.

When a strong connection is to be obtained by using a heat welding material such as solder 15 as an electric connection material, in the present embodiment, the connection portion C of the signal board S is relatively hard and has a heat-resistant base material. (Here, ceramic), the connection portion C of the signal board S can be easily positioned with respect to the ground electrode 61 and the drive electrode 62 from which the electrodes have been drawn as described above, and Can be connected by a single heat treatment.

(Second Embodiment) FIG. 4 is a sectional view in the slice direction showing an ultrasonic transducer according to a second embodiment of the present invention. As shown in the figure, the piezoelectric body of the present embodiment is a composite piezoelectric body composed of a columnar piezoelectric ceramic 1 and a resin 7 filled in the gap. This composite piezoelectric body has a burned silver electrode 4 formed on the back surface at the time of manufacture and is separated by a resin 7. A common thin film electrode 6 is formed on the outside to electrically connect these. I have. The common thin film electrode 6 is also formed on the front surface of the composite piezoelectric body. The back side common thin film electrode 6 functions as a drive electrode of the transducer, and the front side common thin film electrode 6 functions as a ground electrode.

Particularly, in the present embodiment, the baked silver electrode 4 on the back surface of the piezoelectric ceramic 1 is provided at the edge in the slice direction.
However, it has a spiral electrode structure extending to a part of the front surface via the side surface of the piezoelectric ceramic 1. The FPC 5 for leading the drive electrode of the composite piezoelectric body is electrically connected to such a circulating electrode 4 at the position of the front surface (the surface in contact with the acoustic matching layer 2) of the piezoelectric body, for example, by soldering.

An array of transducers is formed after the drive electrode lead-out FPC 5 is connected to the piezoelectric body.
According to the present embodiment, since there is no structural discontinuity on the back side (backing material 3 side) of the composite piezoelectric body which is considered to be poor in workability, it is possible to reduce electrode breakage failure on the back side. Can be. In the present embodiment, a composite structure of the thin film electrode 6 and the baked silver electrode 4 is adopted as the back electrode structure, but the present invention is not limited to this and can be changed as appropriate. Further, the above-mentioned circulating electrode is formed by the baked silver electrode 4, but is not limited to this. In addition, FPC5
The connection method may be performed not only by soldering but also by, for example, a conductive adhesive.

(Third Embodiment) FIG. 5 is a sectional view in the slice direction showing an ultrasonic transducer according to a third embodiment of the present invention. The piezoelectric body of this embodiment is a composite piezoelectric body composed of a columnar piezoelectric ceramic 1 and a resin 7 filled in a gap between the piezoelectric ceramics 1 and 2 as in the second embodiment. This composite piezoelectric body has a burned silver electrode 4 formed on the back surface at the time of manufacture and is separated by a resin 7. The common thin film electrode 6 is used to electrically connect these.
Are formed on the outside. The common thin film electrode 6 is also formed on the front surface of the composite piezoelectric body. Back side common thin film electrode 6
Functions as a drive electrode of the transducer, and the common thin-film electrode 6 on the front side functions as a ground electrode.

Particularly, in the present embodiment, the baked silver electrode 4 on the back surface of the piezoelectric
However, it has a spiral electrode structure extending to a part of the front surface via the side surface of the piezoelectric ceramic 1. Further, the FPC 5 for leading the drive electrode of the composite piezoelectric body is disposed on the side surface of the transducer so that the tip thereof protrudes from the front surface of the piezoelectric body. Connected. Note that, as shown in FIG. 6, the FPC 5 may be arranged and connected so that the front end of the FPC 5 does not protrude from the front surface of the piezoelectric body.

According to this embodiment, the back side (backing material 3 side) of the composite piezoelectric body which is considered to have poor workability.
In addition, since there is no structural discontinuity, it is possible to reduce electrode breakage failure on the back side. Further, it is possible to increase the distance between the resin 7 located at the outermost edge of the composite piezoelectric body and the connection portion of the FPC 5, and it is possible to reduce electrode tear failure on the back surface even after the array dividing step.
Further, the connection area of the FPC 5 can be reduced, and the effective aperture in the slice direction can be increased.

In this embodiment, a composite structure of the thin film electrode 6 and the baked silver electrode 4 is adopted as the back electrode structure, but the present invention is not limited to this and can be changed as appropriate. Also,
The above-mentioned circulating electrode is formed by the baked silver electrode 4, but is not limited to this.

Also, as shown in FIGS. 5 and 6, in this embodiment, the connection of the FPC 5 is made by the conductive adhesive 8, but the connection is not limited to this, and it may be made by soldering or the like.

(Fourth Embodiment) FIG. 7 is a sectional view in the slice direction showing an ultrasonic transducer according to a fourth embodiment of the present invention. The piezoelectric body of this embodiment is a composite piezoelectric body composed of a columnar piezoelectric ceramic 1 and a resin 7 filled in a gap between the piezoelectric ceramics 1 and 2 as in the second embodiment. This composite piezoelectric body has a burned silver electrode 4 formed on the back surface at the time of manufacture and is separated by a resin 7. The common thin film electrode 6 is used to electrically connect these.
Are formed on the outside. The common thin film electrode 6 is also formed on the front surface of the composite piezoelectric body. Back side common thin film electrode 6
Functions as a drive electrode of the transducer, and the common thin-film electrode 6 on the front side functions as a ground electrode.

In particular, in this embodiment, a back acoustic matching layer 9 made of a member having better workability than the backing material 3 is formed on the back surface of the piezoelectric body so as to cover the connection portion of the FPC 5. The back acoustic matching layer 9 is formed by filling an inorganic material in epoxy resin, for example.

The back side electrode (common thin film electrode 6) is appropriately protected by the covering of the back side acoustic matching layer 9, so that it is possible to reduce electrode breakage defects on the back side even after the array dividing step. In the array dividing step, the rear acoustic matching layer 9 can be divided, and a processing of dividing the dividing groove in the middle of the rear acoustic matching layer 9 is also possible.

In the present embodiment, a composite structure of the thin film electrode 6 and the baked silver electrode 4 is adopted as the back electrode structure, but the present invention is not limited to this and can be changed as appropriate. Further, the back acoustic matching layer 9 is made of an epoxy resin filled with an inorganic substance. When the back acoustic matching layer 9 is formed of a conductive member, it is necessary to completely divide the array in the array dividing step.

Although the drive electrode lead-out FPC 5 is connected to the back surface of the piezoelectric body, the present invention is not limited to this, and other structures can be adopted. The present invention is not limited to the above-described embodiment, and can be implemented with various modifications.

[0031]

As described above, according to the present invention, a connection member having the same thickness as or less than the acoustic matching layer is provided at the end of the common electrode, and the ground electrode is provided on the side of the piezoelectric body of the signal board. , The ground electrode can be pulled out from the side of the piezoelectric body in the same direction as the drive electrode. At this time, the connecting member does not hinder the formation of the acoustic matching layer or the addition of the acoustic lens. In addition, since the signal board is provided with the lead for both the drive electrode and the ground electrode and is drawn out at the connection portion on the side surface of the piezoelectric body, the electrode can be easily and firmly pulled out. Furthermore, in a case where a strong connection is to be obtained by using a heat welding material such as solder as an electrical connection material of the connection portion, the connection portion of the signal extraction board is formed of a heat resistant material, so that the ground electrode and the drive electrode are connected. The connection can be made by one heating connection.

Further, according to the present invention, it is possible to eliminate the structural discontinuity at the back surface of the piezoelectric plate by changing the connection position of the FPC for leading out the drive electrode from the back surface to the front surface or the side surface of the piezoelectric plate. Become.

Further, by forming an acoustic matching layer on the back surface of the composite piezoelectric body, it is possible to cover and protect the back surface common electrode which is considered to have insufficient adhesion strength and insufficient strength of itself. Becomes These make it possible to reduce defects such as electrode rupture in the array division step.

[Brief description of the drawings]

FIG. 1 is a sectional view in the slice direction showing an ultrasonic transducer according to a conventional example.

FIG. 2 is a sectional view in the slice direction showing a composite piezoelectric array transducer according to a conventional example.

FIG. 3 is a cross-sectional view in the slice direction showing the ultrasonic transducer according to the first embodiment of the present invention.

FIG. 4 is a sectional view in the slice direction showing an ultrasonic transducer according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view in the slice direction showing an ultrasonic transducer according to a third embodiment of the present invention.

FIG. 6 is a diagram showing a modification of the third embodiment.

FIG. 7 is a sectional view in the slice direction showing an ultrasonic transducer according to a fourth embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 piezoelectric ceramic 2 acoustic matching layer 3 backing material 4 baked silver electrode 5 flexible printed circuit board (FPC) 6 common thin film electrode 7 resin 8 conductive adhesive 9 back acoustic matching layer

Claims (12)

[Claims] 1. A piezoelectric body for converting an ultrasonic wave into an electric signal via an acoustic matching layer has a first electrode on a predetermined surface and a second electrode on a surface opposite to the first electrode. An ultrasonic transducer, comprising: a connecting member provided at an end of the piezoelectric body on the first electrode side, the connecting member having the same thickness as or less than the acoustic matching layer, and connecting the first electrode to the connecting member. And the second electrode is drawn out in the same direction as the side face of the piezoelectric body through the first and second electrodes, and the lead-out portions of the first and second electrodes are made substantially coplanar. Transducer. 2. A signal board having a connection portion made of a relatively hard base material and first and second signal lines disposed on the connection portion, wherein the first and second signal lines are provided. The ultrasonic transducer according to claim 1, wherein the first and second electrodes are connected to the lead-out portions of the first and second electrodes via the connection portion. 3. The ultrasonic transducer according to claim 2, wherein the connection portion of the signal board is made of a heat-resistant material. 4. A composite piezoelectric body, comprising: a drive electrode for driving the composite piezoelectric body; and a flexible printed wiring board for leading out the drive electrode, wherein the flexible printed wiring board is formed of the composite piezoelectric body. An ultrasonic transducer electrically connected at a front position. 5. A composite piezoelectric body, a drive electrode provided to extend from a back surface of the composite piezoelectric body to a part of a front surface via a side surface, and for driving the composite piezoelectric body; A flexible printed wiring board connected to the drive electrode at a front position, wherein the formation of the composite piezoelectric body is performed after the flexible printed wiring board is connected to the drive electrode. Ultrasonic transducer. 6. A composite piezoelectric body, comprising: a drive electrode for driving the composite piezoelectric body; and a flexible printed wiring board for leading out the drive electrode, wherein the flexible printed wiring board is formed of the composite piezoelectric body. An ultrasonic transducer electrically connected in a side position. 7. A composite piezoelectric body, a drive electrode provided to extend from a back surface of the composite piezoelectric body to a part of a front surface via a side surface, and for driving the composite piezoelectric body; And a flexible printed wiring board connected to the drive electrode at a side surface position, wherein the array formation of the composite piezoelectric body is performed after connection of the flexible printed wiring board to the drive electrode. Ultrasonic transducer. 8. The ultrasonic transducer according to claim 6, wherein the flexible printed wiring board is provided with a tip protruding toward a front surface of the composite piezoelectric body. 9. The ultrasonic wave according to claim 6, wherein the flexible printed wiring board is provided with its tip held at a position in the middle of the side surface of the composite piezoelectric body or at a position of a backing material. Transducer. 10. An ultrasonic transducer, comprising: a composite piezoelectric body; a back electrode provided on a back surface of the composite piezoelectric body; and a back acoustic matching layer for protecting the back electrode. 11. The ultrasonic transducer according to claim 10, wherein the back acoustic matching layer is formed of a conductive member. 12. The composite piezoelectric body according to claim 4, wherein the composite piezoelectric body is composed of a plurality of divided piezoelectric ceramics and a resin filled in a gap therebetween.
Or the ultrasonic transducer according to any one of 7 or 8 or 9 or 10 or 11.