JPH06225391A - Ultrasonic wave probe and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide an ultrasonic wave probe with high reliability for which the connection method of a vibrator is easy by imparting a pair of electrodes facing to each other in the direction of thickness to a piezoelectric element and extending positive and negative electrodes to mutually opposite side surface parts. CONSTITUTION:In the ultrasonic wave probe constituted of the piezoelectric element, a back load material and a housing on at least more than one acoustic matching layer or acoustic lens, the electrodes 7 and 8 provided with an electrode slit 26 are formed on the upper and lower surfaces of the piezoelectric element 5. Then, side surface electrodes 22 are formed so as to let the end parts of the electrodes 7 and 8 be brought into contact with the side parts of the element 5. By the constitution, even in the ultrasonic transducer of the piezoelectric element 5 whose thickness is made thin by the requests of miniaturization and making a diameter small with high frequencies, the expensive ultrasonic wave probe with the high reliability of connection for which the connection method of the vibrator is easy can be easily obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe used for an ultrasonic endoscope used in medical treatment and the like, and more particularly to an electrode of the ultrasonic probe.

[0002]

2. Description of the Related Art In recent years, ultrasonic probes have shown rapid growth in demand as ultrasonic diagnostic devices for medical use in addition to nondestructive inspection devices. A probe such as an ultrasonic endoscope emits high-frequency acoustic vibrations from an ultrasonic transducer into a living body, receives the reflected ultrasonic waves, and receives the ultrasonic waves with a slight difference in interface characteristics. By processing different information, it is possible to obtain a cross-sectional image of the inside of the living body.

The vibrator of the ultrasonic transducer is roughly divided into a piezoelectric element, an acoustic matching layer and a back load material. The ultrasonic transducer uses an electrode formed on the surface of the piezoelectric element to apply a high-frequency voltage pulse to the piezoelectric element, cause the piezoelectric element to resonate, and cause rapid deformation to generate an ultrasonic pulse. is there.

However, in the case where ultrasonic waves for blood vessels require high frequency and small size, the shape of the piezoelectric element becomes small and the thickness becomes very thin. It's getting very difficult. As a conventional example, one surface of a non-polarized piezoelectric element 52 attached to a non-conductive wire case 51 has conductivity as described in JP-A-3-173547 shown in FIG. The back load material 53 is added so as to have a role as an electrode, and the thin film electrode 54 is formed on the other plane by extending to a non-conductive case, and then polarized to give piezoelectricity. There is something.

As a second conventional example, there is a small ultrasonic probe 55 which is used by inserting it into a body cavity as shown in FIG. This ultrasonic probe 55 is manufactured by using polarized piezoelectric elements 52 after forming a wrap-around electrode on the side surface portion at the same time as the electrode on the main plane portion by baking, plating, vapor deposition or the like.

[0006]

However, a thin film electrode 54 is provided to the piezoelectric element 52 which is not polarized as described in JP-A-3-173547, and conductivity is provided as one electrode. In the ultrasonic probe having the configuration using the back load material 53, the thin film electrode 54 and the back load material 53 of a good conductor are bonded or directly formed on the piezoelectric element 52, and then the polarization operation is performed. The piezoelectric element 52 tends to deform due to the polarization operation, but the back load material 53 mainly regulates this deformation, stress is applied to the piezoelectric element 52, and discharge breakdown or microcracking occurs during polarization. Significantly shorten the life.

Further, the thin film electrode 54 is easily cracked due to the deformation of the piezoelectric element 52 during polarization. Further, the back load material 53 also serving as the thin-film electrode 54 and the electrode is liable to be peeled off between the piezoelectric elements 52 due to strain during polarization, which causes characteristic deterioration.

On the other hand, in the method like the second conventional example, in which the electrical connection is made only by the electrodes provided on the side surface of the piezoelectric element 52 in which the acoustic matching layer 56 and the back load material 57 are laminated, the thickness of the piezoelectric element 52 is reduced. The limit is 20 MHz of about 100 μm.
Above 30MHz, the thickness of the piezoelectric element 52 is 70μ.
m or less, the reliability of electrical connection decreases.

Further, the acoustic matching layer 56 and the back load material 57 are adhered to the piezoelectric element 52, or the acoustic matching layer 5 made of resin is used.
At the time of directly molding 6 or the back load material 57, the adhesive or the resin easily wraps around the electrode portion, which causes deterioration of the characteristics.
Therefore, it is necessary to ensure the reliability of the connection by making the shape of the acoustic matching layer 56 and the back load material 57 smaller than that of the piezoelectric element 52 to ensure the exposure of the electrode portion.

Therefore, the present invention was developed in view of the above-mentioned drawbacks in the prior art, and the shape of the piezoelectric element, which requires higher frequency and smaller size, such as the ultrasonic probe for blood vessels, becomes smaller, An object of the present invention is to provide a highly reliable and inexpensive ultrasonic probe and a method of manufacturing the same by improving a so-called electrode connection method for connecting a vibrator having a very thin thickness.

[0011]

DISCLOSURE OF THE INVENTION The present invention provides an ultrasonic wave comprising at least one acoustic matching layer or an acoustic lens, a piezoelectric element, a back load material, and a housing for fixing them after laminating them. In the probe, a pair of electrodes facing each other in the thickness direction are applied to the piezoelectric element to perform polarization, and then positive and negative electrodes are extended to side surfaces facing each other.

Further, in the ultrasonic probe comprising at least one or more acoustic matching layers or acoustic lenses, a piezoelectric element, a back load material, and a housing for fixing them after laminating them, the piezoelectric element After applying a pair of electrodes facing each other in the thickness direction to perform polarization, at least one or more acoustic matching layers or acoustic lenses or back load materials are laminated and cut to expose positive and negative electrodes, and a piezoelectric element Is a manufacturing method in which the side surface electrode is formed to extend beyond the side surface portion of the piezoelectric element.

Further, in the ultrasonic probe comprising at least one or more acoustic matching layers or acoustic lenses, a piezoelectric element, a back load material, and a housing for fixing them after laminating them, the piezoelectric element The side surface electrode is formed larger than the side surface portion of the piezoelectric element.

[0014]

According to the present invention, even in an ultrasonic transducer having a thin piezoelectric element, the method of connecting the transducer is easy and high reliability can be obtained.

[0015]

Embodiment 1 FIGS. 1 to 4 show a method of manufacturing a piezoelectric element side electrode in this embodiment. FIG. 1 is a perspective view, FIGS. 2 to 4 are side views, and FIGS. It is a side view which shows the manufacturing method of the vibrator part of the ultrasonic probe which used the manufactured piezoelectric element.

A piezoelectric element having several electrodes 7 and 8 as shown in FIG. 1 and having positive and negative electrodes displaced from each other as shown in FIGS. 1 and 2 is manufactured. Specifically, the thickness is 0.11
mm lead titanate (PT) type piezoelectric element (Curie temperature at which spontaneous polarization disappears is about 320 ° C) is prepared by lapping, and silver paste is applied by screen printing and baked to a thickness of about 8 μm. Electrodes 7 and 8 of
Polarization is performed to produce a piezoelectric element as shown in FIG.

Then, the broken line portion as shown in FIG. 2 is cut by a precision cutting machine to manufacture the piezoelectric element 5 having a cross section as shown in FIG. Then, the piezoelectric element 5 is subjected to a surface treatment such as ion bombardment, vapor deposition is performed at 170 ° C. where the spontaneous polarization does not deteriorate, and a silver electrode is formed on the opposite side surfaces (cut surface) as shown in FIG. The side electrode 22 is produced.

As shown in FIGS. 5 and 6, an acoustic matching layer 4 made of an epoxy resin mixed with an alumina filler is bonded to the piezoelectric element 5 by using an anaerobic adhesive 21.
Then, the back load material 3 is laminated and adhered and cut in the lengthwise direction, and a plurality of transducer portions 25 of the ultrasonic probe are produced. The back load member 3 is composed of an epoxy resin portion 1 containing tungsten powder as a filler and an insulating layer 2 made of only epoxy resin for improving the insulating property, and the insulating layer 2 portion is in contact with the back load member 3. The structure is such that the piezoelectric element 5 is laminated and adhered in accordance with the position of the electrode slit 26 of the surface.

This vibrator portion 25 was fixedly adhered to a housing formed by processing a metal pipe, and positive and negative electrodes were connected to produce an ultrasonic probe 55 as shown in FIG.

When manufactured by the above-mentioned method, since the flat electrode is positioned and cut by using a precision cutting machine, the electrode slit 26 between the positive and negative electrodes can be accurately manufactured, and a plurality of electrodes can be formed at a time. Thin side electrode 2
It is possible to fabricate the piezoelectric element 5 with 2.

Further, the piezoelectric element 5 having the side surface electrode 22 at once
When the electrode is manufactured and polarized, a distortion may occur at the corners of the planar electrodes 7 and 8 and the side surface electrode 22 due to the strain during polarization, and conduction failure may occur when the ultrasonic probe is cut and cut. Since the side surface electrode 22 is provided after the polarization, the conduction failure does not occur.

Furthermore, since the side electrodes 22 are provided on the side surfaces after the plane electrodes 7 and 8 are cut out to expose the plane electrodes 7 and 8, there is no variation in the electrode thickness at the outer peripheral portions of the plane electrodes 7 and 8 caused by the screen printing method. The piezoelectric element 5 in which the silver thickness of the electrodes 7 and 8 is uniform can be produced.

According to this embodiment, the electrode slit spacing can be accurately manufactured, and a plurality of sheets can be manufactured at once, and a thin piezoelectric element with a side electrode can be obtained at low cost. In addition, if a piezoelectric element with side electrodes is manufactured and polarized at one time, distortion may occur at the corners of the flat and side electrodes due to strain during polarization, resulting in poor conduction when cut into an ultrasonic probe. However, since the side surface electrode is provided after polarization, conduction failure does not occur. Furthermore, since the variation in the thickness of the electrode is small, the frequency characteristics of the piezoelectric element are not adversely affected, and the thickness of the acoustic matching layer is easily controlled, so that a good ultrasonic probe can be manufactured.

As the main plane electrode material of the piezoelectric element applied before polarization, a baked electrode of silver or silver alloy or a thick film electrode such as NiP plating is sure, but it is conductive by vapor deposition or sputtering. If it is a thing, the same effect can be obtained. In addition to the vapor deposition, the side surface electrode can be formed by a conductive material such as silver, gold, or a nickel alloy, which can be formed at a temperature below the temperature at which the spontaneous polarization of the piezoelectric element deteriorates, such as sputtering, in order to form an adhesive force with the piezoelectric element. Similar effects can be obtained with some.

[0025]

[Embodiment 2] FIGS. 7 to 10 show a method of manufacturing a transducer portion of an ultrasonic probe in the present embodiment, FIG. 7 being a perspective view and FIG.
And FIG. 9 is a side view. 10 and 11 are a cross-sectional view and a perspective view of an ultrasonic probe using the same. FIG. 12 is a perspective view showing a modified example. The basic configuration of the present embodiment is the same as that of the first embodiment, and the same components are designated by the same reference numerals and only different points will be described.

In this embodiment, as shown in FIG.
Then, the positive and negative silver-baked electrodes 7 and 8 are exposed on opposite side surfaces. In this state, a back load material 27 made of epoxy resin containing zirconia as a filler is adhered to the positive side flat electrode 7 side, and one negative electrode section 8 is
The acoustic matching layer 4 made of an epoxy resin mixed with a filler of alumina and the acoustic lens 16 are formed to produce a vibrator as shown in FIGS.

Next, paying attention to the fact that the acoustic lens 16 is not covered, a silver alloy is applied by sputtering to the side surface of the back load material 27, which is a non-conductor, to form the side electrode 22, and the transducer of the ultrasonic probe is formed. The part 25 is produced. When forming the side surface electrode 22 of this silver alloy, a stronger side surface electrode 22 can be obtained by subjecting the portion where the side surface electrode 22 is formed to a surface treatment by ion bombardment in advance.

The vibrator portion 25 provided with the side electrode 22
Was cut in the X direction using a precision cutting machine, and was fixed to the housing 6 by adhesion, and a mirror type ultrasonic probe 18 using the mirror 23 as shown in FIGS. For the connection from the vibrator portion 25, only the positive lead wire 10 is directly fixed with the conductive adhesive 9, and the negative side is dropped from the side surface electrode 22 to the housing 6 by using a conductive resin, and the housing 6 is disconnected from the coaxial cable 13. It is connected to the negative lead wire 11.

In this embodiment, since the size of the side surface electrode 22 is equal to or larger than the thickness of the piezoelectric element 5, the piezoelectric element 5 is made to have a high frequency.
Even if the thickness becomes thin, the side electrode 22
Can be extended, and the electrode area capable of connection can be increased.

According to the present embodiment, since the size of the side electrode is equal to or larger than the thickness of the piezoelectric element, the side electrode can be extended to the side surface of the back load material even if the piezoelectric element becomes thin due to high frequency. A reliable connection is possible, and a highly reliable ultrasonic probe can be manufactured.

In order to increase the strength of the laminated boundary portion between the piezoelectric element 5 and the back load material 27, as shown in FIG.
The reliability can be improved by encouraging. Also,
In the present embodiment, the insulating back load material 27 using zirconia as a filler was used, but the present invention is not limited to this, and a back load material using a conductive filler such as tungsten may be deposited after forming an insulating film with an epoxy resin or the like. Similar effects can be obtained by performing sputtering or sputtering.

[0032]

Third Embodiment FIG. 13 is a perspective view showing this embodiment. The basic configuration of the present embodiment is the same as that of the second embodiment, and the same components are designated by the same reference numerals and only different points will be described.

In this embodiment, the negative electrode surface 8 of the piezoelectric element 5 having a thickness of about 90 μm at 25 MHz and having the electrode strip as shown in FIG.
A machinable ceramics 4 having a thickness of a wavelength (for example, a product name: Macor Ishihara Chemical Co., Ltd.) is adhered, and an epoxy resin 15 having a thickness of a quarter wavelength is printed and formed as a second acoustic matching layer. A sheet 28 of about 1/4 wavelength of soft polyethylene is adhered. On the other positive electrode side, a back load material 27 made of a resin containing alumina as a filler is formed to manufacture a vibrator as shown in FIG.

Then, as shown by the broken line portion in FIG. 13, it is cut in the Y direction by a precision cutting machine, and the side surface portion with the exposed electrode is
A side electrode is obtained by depositing a silver alloy. Then, the transducer part is cut by cutting in the X direction, and is bonded to the housing via the insulating layer in the same manner as in FIG. 11 of the second embodiment, and is connected to manufacture an ultrasonic probe.

When the piezoelectric element 5 is manufactured by the above-described method, the three acoustic matching layers 4, 15 and 28 are laminated and cut on the piezoelectric element 5, so that the piezoelectric element 5 has the same shape as the piezoelectric element 5 having a uniform thickness. The matching layers 4, 15, 28 can be produced. In addition, the acoustic matching layers 4, 15, 28 and the back load material 27 are connected to the piezoelectric element 5.
Since the side electrodes are provided by cutting after laminating on, the adhesive, the acoustic matching layer, the resin forming the back load material, etc. do not get around.

According to this embodiment, since the acoustic matching layer is laminated and cut on the piezoelectric element, an acoustic matching layer having the same shape as the piezoelectric element having a desired thickness and a uniform thickness can be obtained and high sensitivity can be obtained. As a result, an ultrasonic probe without distortion of the ultrasonic beam can be manufactured. Further, since the acoustic matching layer and the back load material are laminated on the piezoelectric element and then cut to provide the side electrodes, the adhesive, the acoustic matching layer, the resin forming the back load material, etc. do not go around, and the reliability of the connection is improved. An ultrasonic probe with high properties can be produced.

In this embodiment, the acoustic matching layer has a three-layer structure, but the same effect can be obtained if at least one acoustic matching layer or one acoustic lens is provided.

[0038]

As described above, according to the ultrasonic probe and the method of manufacturing the same according to the present invention, in the ultrasonic transducer of the piezoelectric element, the thickness of which is reduced due to the demand for high frequency and small size and small diameter. Also, a method of connecting the transducer, that is, a method of taking the so-called electrodes is easy, and an ultrasonic probe which has high reliability of connection and is inexpensive can be easily obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment.

FIG. 2 is a side view showing the first embodiment.

FIG. 3 is a side view showing the first embodiment.

FIG. 4 is a side view showing the first embodiment.

FIG. 5 is a side view showing the first embodiment.

FIG. 6 is a side view showing the first embodiment.

FIG. 7 is a perspective view showing a second embodiment.

FIG. 8 is a side view showing a second embodiment.

FIG. 9 is a side view showing a second embodiment.

FIG. 10 is a cross-sectional view showing a second embodiment.

FIG. 11 is a perspective view showing a second embodiment.

FIG. 12 is a perspective view showing a second embodiment.

FIG. 13 is a perspective view showing a third embodiment.

FIG. 14 is a cross-sectional view showing a conventional example.

FIG. 15 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1,2,3 Back load material 4 Acoustic matching layer 5 Piezoelectric element 7,8 Electrode 16 Acoustic lens 22 Side electrode 25 Transducer part

Claims (3)

[Claims] 1. An ultrasonic probe comprising at least one or more acoustic matching layers or acoustic lenses, a piezoelectric element, a back load material, and a housing for fixing them after laminating them. A method for manufacturing an ultrasonic probe, characterized in that a pair of electrodes facing each other in the thickness direction are applied and polarized, and then the positive and negative electrodes are extended to the side surfaces facing each other. 2. An ultrasonic probe comprising at least one or more acoustic matching layers or acoustic lenses, a piezoelectric element, a back load material, and a housing for fixing them after laminating them. After applying a pair of electrodes facing each other in the thickness direction to perform polarization, at least one or more acoustic matching layers or acoustic lenses or back load materials are laminated and cut to expose positive and negative electrodes, and a piezoelectric element The method of manufacturing an ultrasonic probe, wherein the side electrode is formed so as to extend beyond the side surface of the piezoelectric element. 3. An ultrasonic probe including at least one or more acoustic matching layers or acoustic lenses, a piezoelectric element, a back load material, and a housing for fixing them after laminating them, wherein the piezoelectric element is used. The ultrasonic probe is characterized in that the side surface electrode is formed larger than the side surface portion of the piezoelectric element.