JPH08205290A - Ultrasonic probe - Google Patents

Abstract

PURPOSE: To prevent the degradation of input/output electrodes and conductive members which connect the input/output electrodes and a piezoelectric element. CONSTITUTION: A piezoelectric element 5 having an electrode on the surface, an acoustic matching layer 4 brought into contact with the ultrasonic radiation face of this piezoelectric element 5, a rear damping material 3 brought into contact with the counter-radiation race or the piezoelectric element 5, input/ output electrodes 7 and 8, conductive members 9a to 9c which electrically connect the piezoelectric element and input/output electrodes, insulating resin with which conductive members are coated, and a housing 6 where they are stored are provided, and input/output electrodes and conductive members 9a to 9c are made of material including a conductive polymer. Since an acoustic medium doesn't penetrate the input/output electrodes and conductive members 9a to 9c, they are not swollen, and their degradation is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe for transmission / reception used in a flaw detection or body cavity ultrasonic diagnostic apparatus for obtaining an ultrasonic tomographic image for diagnosis.

[0002]

2. Description of the Related Art In recent years, ultrasonic probes have been rapidly in demand as medical ultrasonic diagnostic devices in addition to nondestructive inspection devices. This ultrasonic endoscope or other probe radiates high-frequency acoustic vibrations from the ultrasonic transducer into the living body, receives the reflected and returned ultrasonic waves with the ultrasonic transducer, and has a slight interface characteristic. By processing different information depending on the difference, the cross-sectional image of the inside of the living body is obtained.

The ultrasonic probe is roughly divided into a piezoelectric element, an acoustic matching layer, and a back damping material. An electrode formed on the surface of the piezoelectric element is used to apply a high frequency voltage pulse to the piezoelectric element. When applied, the piezoelectric element is caused to resonate to rapidly deform and generate an ultrasonic pulse.

However, in the case of an ultrasonic probe for blood vessels which requires high frequency and miniaturization, the shape of the piezoelectric element becomes small and the thickness is very thin. Since the method and the wiring method have become very difficult, many inventions such as JP-A-5-300593 have been proposed.

6 and 7 show a conventional ultrasonic probe 18 used in an ultrasonic diagnostic apparatus. The acoustic matching layer 4 is provided on the ultrasonic wave emitting surface of the piezoelectric element 5 provided with the surface electrodes 7 and 8, and the rear braking member 3 is provided on the anti-emission surface of the piezoelectric element 5.
Is provided. After the ultrasonic transducer portion 25 is bonded to the conductive housing 6, the surface electrodes 7 and 8 are used as input / output electrodes. Therefore, the surface electrode 7 and the housing 6 are connected by the conductive member 9a to the surface electrode 8 and the lead wire 1.
0 is electrically connected by a conductive member 9c, and the peripheral line 11 and the housing 6 are electrically connected by a conductive member 9b. Then, if necessary, sealing / insulation is performed with an insulating resin. Further, the housing 6 is connected to the flexible shaft 24 by the silver solder 14, so that the ultrasonic probe 18 can be driven in the front-back and rotation directions with respect to the axial direction of the flexible shaft 24.

The ultrasonic probe 18 thus manufactured is inserted into a tubular cover (sheath 29) made of polyethylene or the like, as shown in FIG. The inside of the sheath 29 is liquid paraffin used as an acoustic medium,
It is filled with water, physiological saline, a gel-like substance or the like, and is inserted into the body cavity in this state.

The conductive members 9a, 9b, 9c are
Silver solder, solder, a conductive adhesive, etc. are used, and the periphery thereof is sealed with an insulating resin such as an epoxy resin.
On the other hand, with the recent miniaturization of the ultrasonic probe described above, the conductive adhesive is used in order to prevent destruction due to heat acting on the piezoelectric element and from the viewpoint of excellent workability of a minute portion. Is often used. As this conductive adhesive, as described in JP-A-62-161300, one in which silver powder as a conductive filler is added at a ratio of 50 parts by weight or more to 100 parts by weight of an epoxy resin is known. ing.

On the other hand, as a recent technique, it is described in Japanese Patent Application Laid-Open No. 4-181896 in order to obtain slipperiness at the time of contact between the ultrasonic probe and the human body and to secure chemical resistance of the acoustic lens. As described above, the acoustic lens is coated with a paint in which PTEF particles are dispersed in an organic binder.

[0009]

However, the tip of the ultrasonic probe is immersed in a liquid or gel acoustic medium for acoustic matching. In this structure, while the ultrasonic probe is being used, the acoustic medium is a conductive adhesive (Japanese Patent Laid-Open No. 62-1 / 1987).
61300), the electrodes on the piezoelectric element and the epoxy resin of the acoustic matching layer, either directly or through the epoxy resin sealing layer and permeating through the interface between the conductive filler and the surrounding epoxy resin to provide conductivity. A phenomenon occurs in which the adhesive, the electrodes on the piezoelectric element, and the acoustic matching layer swell.

In the conductive adhesive, the binder resin made of an organic polymer resin such as epoxy cures and shrinks, so that the conductive fillers such as silver powder and copper powder which are added to the adhesive are brought into contact with each other to have conductivity. However, there is a problem that the contact between the conductive fillers is cut off due to the swelling described above and the conductivity is lost, or the resistance increases and the characteristics deteriorate. In addition, the penetration of the acoustic medium causes not only the deterioration of the conductive adhesive, but also the deterioration of the input / output electrodes, the rear damping material, and the acoustic matching layer itself formed of the conductive adhesive, such as peeling and swelling. .

Among the acoustic media, physiological saline and ultrasonic gel generally used contain alkali ions, so that they penetrate the sealing layer of epoxy resin and are used as the acoustic matching layer in ceramics such as alumina. There is also a problem of attacking ceramics and electrodes such as PZT, lead titanate, PLZT, and lead metaniobate used in piezoelectric elements. This problem also applies to solder that does not use a conductive adhesive, for example.

In the invention described in Japanese Patent Laid-Open No. 4-181896, the acoustic resin is coated on the acoustic lens, but the acoustic medium also penetrates from a portion other than the coated acoustic lens, for example, an adhesive layer or the like. Therefore, there is a problem of deterioration. Fluororesin consists of PTFE particles, thermoplastic or thermosetting resin, and a curing agent, and
However, if the other thermoplastic or thermosetting resin is hydrophilic having a polar group, the acoustic medium actually penetrates into the interior from this coat layer and causes characteristic deterioration. Although the above publication does not describe the specific components of the fluororesin, none of the commercially available paints solves this problem.

The present invention has been made in view of these circumstances. An object of claim 1 is to provide at least a conductive member electrically connecting a piezoelectric element and an input / output electrode with an acoustic medium component. An object of the present invention is to provide an ultrasonic probe that can prevent penetration and swelling and characteristic deterioration.

It is an object of the present invention to provide an ultrasonic probe capable of preventing the acoustic medium from invading the input / output electrodes of the piezoelectric element and swelling to cause characteristic deterioration. An object of claim 3 is to provide an ultrasonic probe in which the conductivity of the conductive member is obtained at a high value. It is an object of the present invention to provide an ultrasonic probe that is easy to assemble by improving workability as a conductive member. The object of claims 5 and 6 is
An object of the present invention is to provide an ultrasonic probe having a long-term durability of electric characteristics as a conductive member. The purpose of claim 7 is
An object of the present invention is to provide an ultrasonic probe which can be easily processed as an acoustic matching layer forming member and has long-term durability of various characteristics.

[0015]

According to a first aspect of the present invention, a conductive member that electrically connects a piezoelectric element and an input / output electrode does not contain a conductive filler, but has conductivity itself. The use of a water-soluble polymer can prevent the liquid or gel acoustic medium component from penetrating and swelling, resulting in characteristic deterioration. Since the conductive polymer itself is hydrophobic, a hydrophilic acoustic medium penetrates
Since it does not swell and does not contain a filler as in a conductive adhesive, the acoustic medium component does not penetrate from the interface between the filler and the binder resin. Therefore, it is possible to prevent the deterioration of the electrical characteristics of the electrical connection portion of the ultrasonic probe. In addition, since the conductive polymer has a π-conjugated electron arrangement in the whole molecule, a flow of electrons rapidly occurs upon application, and good conductivity is exhibited. Note that many conductive polymers are unstable when exposed to the air in the naked state, and may form a protective film that blocks air at the interface with the air.

According to a second aspect of the present invention, the input / output electrodes of the piezoelectric element use a conductive polymer that does not contain a conductive filler and has conductivity itself, and thereby a liquid or gel state is obtained. It is possible to prevent the acoustic medium from penetrating and swelling to cause characteristic deterioration.

According to the third aspect of the present invention, the conductive member is doped with a dopant, which increases the conductivity of the conductive member to the same extent as solder. The dopant can be selected from a small one such as a halogen ion, a macrocyclic molecule such as phthalocyanine, and a polymer electrolyte, and it is selected according to the type and specifications of the conductive polymer to be used.

According to a fourth aspect of the present invention, the conductive polymer is soluble in a solvent, so that the workability and the low-temperature curability, which are equivalent to those of the solvent-volatile adhesive, are exhibited. As a result, the workability as a conductive member is enhanced, assembly becomes easy, and sufficient conductivity can be secured. A usual conductive polymer is in the form of a powder or a film that is insoluble in a solvent, and is difficult to use as it is for assembly. In the present invention, the processability is improved by introducing a functional group having compatibility with a solvent into the molecule and modifying it even if the conductivity is lowered to some extent.

The invention of claim 5 provides a conductive member in which not only a conductive polymer but also a non-conductive polymer is mixed, whereby long-term durability and stability of conductivity are improved, and electric characteristics are improved. The long-term durability of can be secured. The reason for this is not clear, but probably because the barrier effect of the non-conductive polymer prevents the invasion and permeation of oxygen into the air-exposed portion of the surface, and the effect of the non-conductive polymer to enhance the film-forming property. This is probably because there is.

According to a sixth aspect of the present invention, a hydrophobic amorphous polyolefin is used as the non-conductive polymer used in the fifth aspect, whereby a conductive polymer from the periphery of a hydrophilic acoustic medium or the like is used. Can be further suppressed, and the above-mentioned various characteristics can be stabilized.

According to a seventh aspect of the present invention, the constituent material of the acoustic matching layer is an amorphous polyolefin resin which is soluble in a specific solvent and is a hydrophobic material, which makes it easy to process and hydrophilic. The adverse effect on the conductive polymer from the periphery of the acoustic medium or the like can be further suppressed, and the above-mentioned various characteristics can be stabilized.

[0022]

Embodiment 1 FIGS. 1 to 5 show Embodiment 1 of the present invention, in which the same elements as those in FIGS. 6 and 7 are designated by the same reference numerals. FIG. 1 and FIG. 2 show a method of manufacturing the vibrator part 25 of the ultrasonic probe, and FIGS. 3 and 4 show the manufactured vibrator part 25.
FIG. 5 shows a cross section of the ultrasonic probe.

A piezoelectric element 5 having a GND electrode 7 and a + side electrode 8 formed on the surface thereof is produced by sputtering molybdenum. For this piezoelectric element 5, as shown in FIG. 1, an acoustic matching layer 4 made of, for example, an amorphous polyolefin resin manufactured by Nippon Zeon Co., Ltd., a trade name “ZEONEX TR-1”.
Is bonded to the GND electrode 7 side. On the other hand, the back load material 1 made of a two-liquid mixed type epoxy resin mixed with about 15 times the weight of the tungsten filler as the weight ratio is joined to the + side electrode 8 side to produce a laminated body. At this time, the amorphous polyolefin resin is a 60 wt% toluene solution, and the GND electrode 7
After applying to the side, the solvent is gradually volatilized while pressing to form the acoustic matching layer 4.

Then, as shown by an arrow 40 in FIG. 2, the sheet is cut by a precision cutting machine to produce one small vibrator portion 25 as shown in FIG. 3 or 4. In FIG. 3, only the back load material 1 made of an epoxy resin containing tungsten filler is used as the back braking material 3. FIG. 4 shows a back load material 1 made of an epoxy resin containing a tungsten filler and a back load material 2 made of an epoxy resin not containing tungsten for insulation, after being first attached to the piezoelectric element 5 and the + electrode 8. An epoxy resin containing a tungsten filler is additionally attached to form the back braking material 3.

As shown in FIG. 5, the vibrator portion 25 (hereinafter referred to as a transducer) is adhered and fixed on the insulating plate 19 fixed to the housing 6 in which the metal pipe is processed with an adhesive. Then, the thick electrode portion exposed on the side surface portion of the transducer 25 is connected through the conductive members 9a to 9c. At that time, the GND electrode 7 on the sound radiation surface side is connected to the housing 6 by the conductive member 9a. The pipe portion of the housing 6 is connected to the peripheral line 11 of the coaxial cable 13 passing through the flexible shaft 24 by a conductive member 9b. On the other hand, the wiring of the + side electrode 8 is connected by a conductive member 9c on the back load material 1 in order to ensure insulation with the housing 6, and the conductive member 9c and the peripheral line 1 are connected.
1 and 1 are connected by a lead wire 10. In this way, the ultra-small ultrasonic probe 18 was manufactured.

The conductive members 9a to 9c are, for example, solvent-soluble polyaniline-based conductive polymers manufactured by Nitto Denko Corporation.
The product name "Anilead" consists of 10w of this polymer.
It is formed by applying a t% N-methyl-2-pyrrolidone solution, volatilizing and drying the solvent, and then doping with a protonic acid as a specific acceptor dopant and crosslinking. Even as it is, it has high heat resistance and chemical resistance, and because of its electronic conductivity, there is no humidity dependence of electrical conductivity or surface resistance.
The conductivity is stable in the atmosphere for a long time. In this embodiment, the surface is further sealed and protected by the amorphous polyolefin resin 12 used for forming the acoustic matching layer 4. Further, the housing 6 and the flexible shaft 24 are brazed by the silver solder 14. The housing 6 is formed by subjecting corrosion-resistant stainless steel to electroless nickel plating.

In this embodiment, the ultrasonic probe 18 is used.
Since the acoustic matching layer 4 is formed of the hydrophobic amorphous polyolefin resin, it is possible to prevent the acoustic medium from entering the acoustic matching layer 4 and swelling. In addition, the conductive members 9a to
By forming 9c with a conductive polymer and further coating the surface with an amorphous polyolefin resin, it is possible to prevent the acoustic medium from penetrating into the conductive members 9a to 9c and swelling.

Therefore, the acoustic medium does not swell the acoustic matching layer 4 and the conductive members 9a to 9c, and does not deteriorate the acoustic characteristics and the conductivity. In addition, the hydrophilic ultrasonic gel containing the physiological saline or the commonly used alkali ions in the acoustic medium passes through the coating layer of the amorphous polyolefin resin, and the conductive members 9a to 9c, and Ceramics such as PZT, lead titanate, PLZT and lead metaniobate, which are the piezoelectric elements 5, and electrodes are not affected.
Therefore, according to the present embodiment, there is no deterioration in the characteristics and materials due to the acoustic medium, and the ultrasonic transducer is small in size and has high durability and high performance. In particular, since the surfaces of the acoustic matching layer 4 and the conductive member 9 are formed of or covered with the chemical resistant amorphous polyolefin resin, the result is that the sterilization by gas or steam is more durable than before. have.

Here, the conductive polymer material is not limited to the polyaniline used in this embodiment, but soluble polythiophene series, soluble polyacetylene, poly p-phenylene,
A polyarylene vinylene type, a soluble polypyrrole, a polyarylene metalide type, etc. may be used alone or may be used after being subjected to a doping treatment. The dope may be self-doping type polyaniline-SO ₃ H or the like in which a dopant is covalently introduced into the polymer skeleton. Further, a polymer obtained by graft- or block-copolymerizing a conjugated polymer chain with a saturated polymer and a complex obtained by polymerizing the conjugated polymer in a saturated polymer can also be used. The amorphous polyolefin resin is not limited to "Zeonex" manufactured by Nippon Zeon Co., Ltd., but the product name "APO" manufactured by Mitsui Petrochemical Co., Ltd. or the product name "Arton" manufactured by Japan Synthetic Rubber Co., Ltd. Can be used.

[0030]

Example 2 In Example 2, instead of forming the GND electrode 7 and the + electrode 8 on the piezoelectric element 5 by sputtering molybdenum in Example 1, polyaniline-based conductive material manufactured by Nitto Denko Corporation Polymer, trade name "Anilead"
Was used. A 10 wt% N-methyl-2-pyrrolidone solution of this was applied onto the piezoelectric element 5, the solvent was volatilized and dried, and then a protonic acid as a specific acceptor dopant was doped to form a crosslink. Except for this, it was manufactured in the same manner as in Example 1. The method of using "anilead" is the same as that in Example 1.

The ultrasonic probe 1 thus created
8 has the same actions and effects as those of the first embodiment, and since the electrode on the surface of the piezoelectric element 5 is also formed of a hydrophobic conductive polymer, the acoustic medium penetrates from the side electrode portion of the piezoelectric element 5. The swelling can be prevented, and the ultrasonic probe 18 has higher long-term reliability than that of the first embodiment.

[0032]

Third Embodiment In this embodiment, in the second embodiment, the GND electrode 7 and the + electrode 8 on the piezoelectric element 5, and the conductive member 9a.
Instead of using the polyaniline-based conductive polymer “Anilead” manufactured by Nitto Denko Corporation for 9c alone, a composite blend material of this “Anilead” and an amorphous polyolefin resin was used. This blend uses a non-polar solvent-soluble type of "Anilead" and mixes "Anilead" and Nippon Zeon's amorphous polyolefin resin, trade name "Zeonex TR-1" in a weight ratio of 3: 2. Then, it was performed by preparing a solution in which 40 wt% was dissolved in xylene. Then, this solution is applied to volatilize and remove the solvent, and the GND electrode 7 and the + electrode 8 on the piezoelectric element 5 and the conductive member 9 are formed.
a, 9b and 9c were formed.

The ultrasonic probe 1 thus created
8 has the same action and effect as in Example 1, and further, the GND electrode, the + electrode, and the conductive member on the surface of the piezoelectric element 5 are made of a blend resin material of a hydrophobic amorphous polyolefin resin and a conductive polymer. Since it is formed by the above method, the long-term stability of the electric characteristics of the conductive polymer can be obtained, and the ultrasonic probe 18 has higher long-term reliability than that of Example 1. The amorphous polyolefin resin used in this example is useful because of its high hydrophobicity.
Alternatively, polyvinylidene fluoride can be used. Further, although the hydrophobicity is slightly lowered, various non-conductive polymers such as polyimide resin, polymethylmethacrylate resin, polymethylpentene resin, polyvinyl chloride resin and polyvinyl alcohol resin can be selected.

[0034]

According to the ultrasonic probe of the present invention, the acoustic medium does not invade the acoustic matching layer or the conductive member to swell, and the acoustic characteristics and conductivity are not deteriorated. In addition, the hydrophilic ultrasonic gel permeates the coating layer of the amorphous polyolefin resin to form a conductive member, a piezoelectric element such as PZT, lead titanate, PLZT or lead metaniobate, or an electrode. Will not invade. Therefore, it is possible to manufacture a high-performance ultrasonic transducer that is small in size and has high durability without deterioration of characteristics and materials due to the acoustic medium. Furthermore, since the surfaces of the acoustic matching layer and the conductive member are formed or covered with the chemical resistant amorphous polyolefin resin, the acoustic matching layer and the conductive member have more durability than before even against sterilization by gas or steam.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a transducer portion of an ultrasonic probe of the present invention.

FIG. 2 is a perspective view showing cutting of a vibrating portion of an ultrasonic deep probe.

FIG. 3 is a cross-sectional view of a vibrating portion of an ultrasonic deep probe.

FIG. 4 is a cross-sectional view of a vibrating portion of an ultrasonic deep probe.

FIG. 5 is a cross-sectional view of an ultrasonic probe.

FIG. 6 is a cross-sectional view of a conventional ultrasonic probe.

FIG. 7 is a cross-sectional view showing a usage state of an ultrasonic deep probe.

[Explanation of symbols]

 3 Back Load Material 4 Acoustic Matching Layer 5 Piezoelectric Element 7 Surface Electrode 8 Surface Electrode 9a Conductive Member 9b Conductive Member 9c Conductive Member 18 Ultrasonic Deep Probe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Hiji ▼ Masaido 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Inventor Hiroaki Kasai 2-43 Hatagaya, Shibuya-ku, Tokyo No. 2 Olympus Optical Co., Ltd. (72) Inventor Norihiko Sawada 2-43, Hatagaya, Shibuya-ku, Tokyo No. 43-2 Olympus Optical Co., Ltd. (72) Inventor Katsuhiro Wakabayashi 2-chome Hatagaya, Shibuya-ku, Tokyo No. 43-2 Olympus Optical Co., Ltd.

Claims (7)

[Claims] 1. A piezoelectric element having an electrode on its surface, an acoustic matching layer in contact with an ultrasonic wave emitting surface of the piezoelectric element, a back damping material in contact with an anti-radiating surface of the piezoelectric element, and inputting / outputting current to / from the piezoelectric element. An input / output electrode, a conductive member that electrically connects the piezoelectric element and the input / output electrode, an insulating resin that covers the conductive member, and a housing that houses these.
An ultrasonic probe, wherein at least the conductive member is made of a material containing a conductive polymer. 2. A piezoelectric element having an electrode on its surface, an acoustic matching layer in contact with an ultrasonic wave emitting surface of the piezoelectric element, a back braking material in contact with an anti-radiating surface of the piezoelectric element, and inputting / outputting current to / from the piezoelectric element. An input / output electrode, a conductive member that electrically connects the piezoelectric element and the input / output electrode, an insulating resin that covers the conductive member, and a housing that houses these.
An ultrasonic probe, wherein at least the input / output electrodes are made of a material containing a conductive polymer. 3. The ultrasonic probe according to claim 1, wherein the conductive polymer contains at least a doped conductive polymer. 4. The ultrasonic probe according to claim 1, wherein the conductive polymer contains at least a solvent-soluble conductive polymer. 5. The ultrasonic probe according to claim 1, wherein the material containing the conductive polymer is a polymer alloy material of a conductive polymer and a non-conductive polymer. Child. 6. The ultrasonic probe according to claim 5, wherein the non-conductive polymer in the material containing the conductive polymer is at least an amorphous polyolefin resin. 7. A piezoelectric element having an electrode on its surface, an acoustic matching layer in contact with an ultrasonic wave emission surface of the piezoelectric element, a back braking material in contact with an anti-emission surface of the piezoelectric element, and inputting / outputting current to / from the piezoelectric element. An input / output electrode, a conductive member that electrically connects the piezoelectric element and the input / output electrode, an insulating resin that covers the conductive member, and a housing that houses these.
An ultrasonic probe in which at least the acoustic matching layer is made of an amorphous polyolefin resin.