JP2002153461A - Ultrasonic vibrator and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce ground impedance in the case of manufacturing an ultrasonic vibrator. SOLUTION: Backing is provided on the lower surface side of a piezoelectric body and the backing is wrapped by copper foil 32. The copper foil 32 is electrically connected to ground lines 20B and 20C provided on a flexible circuit board 18 and also electrically connected to the upper surface electrode of each vibration element through a wire 35. By effectively constituting the ground line, the ground impedance is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ultrasonic transducer for ultrasonic diagnosis and a method of manufacturing the same.

[0002]

2. Description of the Related Art In order to improve the image quality of an ultrasonic image, the number of elements in an array transducer and the pitch thereof have been reduced. On the other hand, there is also a demand for miniaturization of an ultrasonic probe incorporating such an array transducer, so that a wiring space in the ultrasonic probe is becoming smaller. From these circumstances, the FP connected to the array transducer
The wiring patterns on C (flexible circuit board) are also becoming denser, and the width and spacing of each line are becoming smaller.

[0003] Therefore, the ground impedance has become particularly high, which makes it easy for external noise to be mixed in.
There is a problem that frequency characteristics are also likely to deteriorate. Increasing the width of the ground (earth) line itself in the FPC is limited in space, and another method for reducing the ground impedance is demanded.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to reduce the ground impedance of an ultrasonic transducer and improve the quality of an ultrasonic image.

[0005]

Means for Solving the Problems (1) In order to achieve the above object, the present invention provides a piezoelectric element for transmitting and receiving ultrasonic waves,
A flexible circuit board provided on the lower surface side of the piezoelectric body and having a lead line and an earth line, and a backing layer provided on the lower surface side of the flexible circuit board,
Provided along at least one surface of the backing layer,
A conductive film electrically connected to the ground line.

According to the above structure, the conductive layer is provided along at least one surface of the backing layer, and is electrically connected to the ground line (ground line).
The ground impedance of the ultrasonic probe can be reduced. Therefore, it is more resistant to extraneous noise. Further, there is an advantage that it is not necessary to secure a special arrangement space in the arrangement of the conductive film. The conductive film is preferably a metal foil such as a copper foil, and such a configuration facilitates processing such as bending. An ultrasonic probe incorporating the ultrasonic transducer according to the present invention is used in contact with a body surface or inserted into a body cavity. In addition to the so-called 1D array transducer, 2
The present invention may be applied to other types such as a D-array vibrator. Usually, one or a plurality of matching layers are provided on the upper surface side of the piezoelectric body, and an acoustic lens is further provided on the upper side.

Preferably, the conductive film includes a lower surface cover that covers a lower surface of the backing layer, a first side cover that covers a first side of the backing layer, and a second side that covers a second side of the backing layer. The flexible circuit board includes a side cover portion and a third side cover portion covering a third side surface of the backing layer, wherein the flexible circuit board is formed by being bent from an upper surface of the backing layer to a fourth side surface. The entire layer is substantially surrounded by the flexible circuit board and the conductive film.

According to the above configuration, the conductive film can be provided on most of the outer surface of the backing layer, and the ground impedance can be effectively reduced without requiring a large space.

Preferably, the conductive film has at least one arm extending from at least one of the plurality of covers, and the arm is electrically connected to the ground line. By forming a connection portion in advance in forming the conductive film in this manner, electrical connection is facilitated and manufacturing cost can be reduced.

Preferably, a pair of ground lines are formed at both ends of the flexible circuit board, and the conductive film has a pair of arm portions corresponding to the pair of ground lines.

(2) To achieve the above object,
The present invention provides a step of providing a flexible circuit board having a lead line group and at least one ground line on a lower surface side of a piezoelectric body on which an upper electrode layer and a lower electrode layer are formed; Providing a backing layer; cutting the piezoelectric body into a plurality of vibrating elements; providing a conductive film along at least one surface of the backing layer; and electrically connecting the conductive film to the ground line. And electrically connecting an upper electrode layer of each of the vibrating elements to the conductive film, wherein the electrical impedance of the ground line is reduced by using the conductive film. .

Preferably, in the step of electrically connecting the upper electrode layer of each of the vibrating elements to the conductive film, a connecting member is provided along a direction in which the plurality of vibrating elements are arranged. The upper electrode layer of each vibration element is electrically connected, and at least one end of the connecting member is electrically connected to the conductive film.

Although it is possible to provide a ground electrode such as copper foil on the upper electrode layer of the piezoelectric body, it is also possible to use the upper electrode layer as a ground electrode as it is, in which case, as described above, The upper electrode layers of the respective vibration elements are electrically connected to each other. In this configuration, the piezoelectric body is wrapped by the ground electrode from substantially the entire periphery including the backing layer, and becomes stronger against external noise. Therefore, the image quality of the ultrasonic image can be improved.

Preferably, in the step of providing a conductive film on the backing layer, the lower surface, the first side surface,
The conductive film is bent and formed along the second side surface and the third side surface.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

1 to 8 show an ultrasonic transducer according to the present invention and a method for manufacturing the same. The ultrasonic transducer is provided in the ultrasonic probe, and performs ultrasonic diagnosis by transmitting and receiving ultrasonic waves.

In FIG. 1, a flat plate type piezoelectric body 10 is made of, for example, a known material such as PZT. A first matching layer 12 is bonded to the upper surface 10A of the piezoelectric body 10, and a second matching layer 14 is bonded to the upper surface of the first matching layer 12.
Are adhered. These matching layers 12 and 14 are well-known members for achieving acoustic matching between the acoustic lens provided thereon and the piezoelectric body 10. Of course, one matching layer may be provided without providing the two matching layers 12 and 14.

A flexible circuit board (FPC) 18 is electrically connected to the lower surface 10B of the piezoelectric body 10 by soldering or the like. Specifically, the FPC 18 has an electrode pattern 20 made of bare copper foil or the like on the upper surface side. The electrode pattern 20 includes a plurality of lead lines 20D corresponding to the plurality of vibrating elements, and a pair of ground lines 20B and 20C formed at both ends of the lead lines 20D. In the figure, reference numeral 20A indicates a region to be soldered to the lower surface 10B of the piezoelectric body 10. Of course, a so-called conductive adhesive or the like may be used instead of such soldering.

Incidentally, an upper surface electrode layer is formed on the upper surface 10A of the piezoelectric body 10, and a lower surface electrode layer is formed on the lower surface 10B of the piezoelectric body 10, but these are not shown. The upper electrode layer 10A functions as a so-called ground electrode, and the lower electrode layer functions as a so-called signal electrode.

Incidentally, a copper foil as a ground electrode may be further provided between the piezoelectric body 10 and the first matching layer 12.

The first assembly 22 is formed by performing the bonding process as shown in FIG.

FIG. 2 shows a step of providing a backing layer 24 on the first assembly 22. In particular,
The first assembly 22 is adhered to the upper surface of the backing layer 24. As a result, as shown in FIG.
Is configured. Incidentally, a plate-like reinforcing member or the like may be provided on the lower surface side of the backing layer 24. In this case, the backing layer 24 is provided together with the reinforcing member.
Is wrapped in a copper foil described later.

After performing the bonding step shown in FIG. 2, FIG.
The FPC 18 is folded along the edge of the backing layer 24, as shown in FIG.
The FPC 18 is formed along the side surface from the upper surface of the FPC 4. Such folding can be performed, for example, manually, but may be automated.

Next, as shown in FIG. 4, cutting is performed on the piezoelectric body 10 using a dicing mechanism or the like. Specifically, as shown by a cutting line 30 in FIG. 4, the piezoelectric body 10 is separated into a plurality of elements (vibration elements). In this case, it is desirable that the cut depth is at least such that the electrode pattern 20 formed on the piezoelectric body 10 and the FPC 18 is cut. As a result, the plurality of lead lines 20D are electrically separated from each other. Incidentally, the signal lines constituting the multi-core cable are connected to the hanging lower end of the electrode pattern 20 by soldering or a connector.

Incidentally, the pair of ground lines 20B and 20C formed on both sides of the FPC 18 are also electrically separated from the respective lead lines 20D by the cutting as shown in FIG.

Next, as shown in FIG. 5, the copper foil 32 is
It is provided for the assembly 26. The copper foil 32 includes a lower surface cover portion 32A and a first side surface cover portion 32 as illustrated.
B, the second side cover 32C, and the third side cover 3
2D and a pair of arm parts 32E and 32F, and these parts are integrated.

Each part is constituted as described above.
As will be described later with reference to FIG. 6, this is for enclosing substantially the entire backing layer 24 with the copper foil 32 itself, and this copper foil 32 is used for a pair of ground lines 20B and 20C as described later. By being electrically connected, ground impedance can be significantly reduced.

As shown in FIGS. 5 and 6, the lower surface cover portion 32A is adhered to the lower surface of the backing layer 24. Similarly, the first side surface cover portion 32B is bonded to the backing layer 24.
The second side cover 32C is bonded to the second side of the backing layer 24, and the third side cover 32D is bonded to the third side of the backing layer 24.
This state is shown in FIG.

By the way, no copper foil 32 is provided on the surface from which the FPC 18 is drawn. However,
As shown later, the pair of arm portions 32E and 32F are bent to the surface from which the FPC 18 is drawn.

That is, as shown in FIG. 7, a pair of arms 32E and 32F are bent on the side surface of the backing layer 24, and the arms 32E and 32F are soldered to a pair of ground lines 20B and 20C, respectively. It is electrically connected by attaching. This allows
The ground lines 20B, 20C and the copper foil 32 have the same potential.

Then, as shown in FIG. 7, each of the vibrating elements formed by conducting the wire 35 made of a conductive member on the upper surface side of the piezoelectric body 10 by cutting as described above. Are electrically connected by soldering or the like.

Then, as shown in FIG. 8, the wire 35 is trimmed to a required length, and both ends 35A and 35C thereof are connected to the second side cover portion 32C and the third side cover 32, respectively.
D is electrically connected by soldering or the like.
In the state shown in FIG. 8, a pair of ground lines 32B and 32
C, the copper foil 32 and the upper surface electrode of each vibration element have the same potential, and the piezoelectric body 10 is substantially wrapped by the ground electrode. Therefore, it is possible to greatly reduce the ground impedance and obtain an advantage of being strong against external noise such as electromagnetic waves.

Therefore, the ultrasonic transducer according to the present embodiment has an advantage that the S / N ratio can be improved and the image quality of the ultrasonic image can be significantly improved.

In the above embodiment, FIGS.
Although the upper electrodes of the respective vibrating elements were electrically connected to each other by the wires 35 as shown in (3), when a ground electrode such as copper foil is provided on the upper surface of the piezoelectric body 10, You may make it solder etc. to the copper foil 32.

According to the experiment of the present inventor, it has been confirmed that the ground impedance can be reduced to one third as compared with the related art, and the noise appearing in the ultrasonic image can be remarkably reduced. In recent years, in particular, the size and pitch of each vibrating element have become extremely small.
Although the electrode pattern 20 in FIG. 8 also has a higher density, according to the present embodiment, it is possible to effectively reduce the ground impedance and obtain the unique effect of improving the image quality of the ultrasonic image as described above.

The backing 24 is made of, for example, an ultrasonic absorber such as rubber, and such a backing effectively absorbs ultrasonic waves radiated from the respective vibrating elements to the rear side. . Since the copper foil 32 is provided so as to enclose such a backing, the shape of the ultrasonic probe that houses the ultrasonic transducer does not need to be particularly large.

[0037]

As described above, according to the present invention,
The ground impedance can be reduced to improve the quality of the ultrasonic image.

[Brief description of the drawings]

FIG. 1 is a view for explaining a manufacturing process of a first assembly.

FIG. 2 is a diagram for explaining a manufacturing process of a second assembly.

FIG. 3 is a diagram illustrating a state where an FPC is bent.

FIG. 4 is a diagram showing cutting.

FIG. 5 is a diagram showing a manufacturing process of a third assembly.

FIG. 6 is a view showing a state in which a copper foil is attached.

FIG. 7 is a diagram showing ground connection using a wire.

FIG. 8 is a diagram showing a completed state of the ultrasonic transducer.

[Explanation of symbols]

10 piezoelectric body, 12 first matching layer, 14 second matching layer,
18 FPC (flexible circuit board), 20 electrode pattern, 22 first assembly, 24 backing layer, 26
2nd assembly, 30 cutting lines, 32 copper foil, 34 3rd assembly, 35 wires.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04R 17/00 330 H04R 31/00 330 332 H01L 41/08 C 31/00 330 41/22 Z

Claims (7)

[Claims] 1. A piezoelectric body for transmitting and receiving ultrasonic waves, a flexible circuit board provided on a lower surface side of the piezoelectric body and having a lead line and an earth line, and provided on a lower surface side of the flexible circuit board. A backing layer, provided along at least one surface of the backing layer;
And a conductive film electrically connected to the ground line. 2. The ultrasonic transducer according to claim 1, wherein the conductive film includes a lower surface cover that covers a lower surface of the backing layer; a first side cover that covers a first side surface of the backing layer; A second side cover that covers a second side of the backing layer; and a third side cover that covers a third side of the backing layer, wherein the flexible circuit board is arranged from a top surface of the backing layer to a fourth side. An ultrasonic vibrator characterized by being bent and formed into a shape, and the entire backing layer is substantially surrounded by the flexible circuit board and the conductive film. 3. The ultrasonic transducer according to claim 2, wherein the conductive film has at least one arm extending from at least one of the plurality of covers, and the arm is connected to the ground line. An ultrasonic transducer which is electrically connected. 4. The ultrasonic transducer according to claim 3, wherein a pair of ground lines are formed at both ends of the flexible circuit board, and the conductive film is a pair of arm portions corresponding to the pair of ground lines. An ultrasonic vibrator comprising: 5. A step of providing a flexible circuit board having a lead line group and at least one ground line on a lower surface side of a piezoelectric body on which an upper electrode layer and a lower electrode layer are formed, and a lower surface side of the flexible circuit board. Providing a backing layer, cutting the piezoelectric body into a plurality of vibrating elements, providing a conductive film along at least one surface of the backing layer, electrically connecting the conductive film to the ground line. Connecting the upper electrode layer of each of the vibrating elements to the conductive film, and using the conductive film to reduce the electrical impedance of the ground line. Method of manufacturing an ultrasonic transducer. 6. The manufacturing method according to claim 5, wherein in the step of electrically connecting the upper electrode layer of each of the vibration elements to the conductive film, a connecting member is provided along an arrangement direction of the plurality of vibration elements. Electrically connecting the upper electrode layer of each of the vibrating elements to the connecting member, and electrically connecting at least one end of the connecting member to the conductive film. Production method. 7. The manufacturing method according to claim 5, wherein in the step of providing a conductive film on the backing layer, the conductive film is bent along a lower surface, a first side surface, a second side surface, and a third side surface of the backing layer. A method for producing an ultrasonic vibrator, characterized by forming.