Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JPS61278299 [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic probe which is used in a medical diagnostic apparatus etc. and controls transmission and reception of ultrasonic waves, and in particular, a portion having a central frequency in a high frequency band of 10 MHz or more and a shallow portion from the surface. The present invention relates to an ultrasonic probe that can be clearly drawn and a method of manufacturing the same. (Conventional technology) Medical ultrasound probes are widely used for non-invasive diagnosis, where dynamic observation is performed using soft tissues such as the abdomen and chest as images by applying to the skin surface, but in order to obtain accurate diagnostic information recently There is an increasing demand for swallowing an ultrasound probe with a high central frequency (usually 7.5 MHz or more) from the mouth and clearly depicting the state of the mucous membrane of the stomach wall as an image. Similar to electromagnetic waves, ultrasonic waves have the property that as the frequency increases, the wavelength decreases and the propagation attenuation also increases. Therefore, a high frequency ultrasound probe is unsuitable for the diagnosis of the deep part of the human body. However, for the purpose of capturing a shallow part as a clear image like inspection of the stomach wall, the high frequency probe has an advantage that the resolution is improved by the shortening of the wavelength of the ultrasonic wave, and the high frequency of the probe gradually Is being developed. An example of the structure of an ultrasound probe conventionally used in a medical ultrasound diagnostic apparatus is shown in FIG. In FIG. 3, reference numeral 10 denotes a longitudinal wave piezoelectric ceramic transducer, which is polarized in the thickness direction and is responsible for generation and detection of ultrasonic waves such as electromechanical energy conversion. The values of 1.4 and 15 contribute to the broadening and loss reduction of the probe. A backing 13 has a function of supporting the piezoelectric transducer and absorbing an ultrasonic wave propagating to the rear of the transducer 10. In the 01-05-2019 1 probe shown in FIG. 2 having a double acoustic matching layer, in order to obtain good ultrasonic pulse transmission characteristics with wide band low loss and low ripple characteristics, the acoustic impedance density (density of the acoustic matching layer 11 (density And a velocity of sound) are aOX10'-10. OX 10 'kg // crown, acoustic impedance density of the acoustic matching layer 12 is 2.0 × 10 ′ to 3.0 × 10′J4 / Me, and the thickness of the acoustic matching layer 11.12 with respect to the resonant frequency of the piezoelectric transducer A quarter wavelength is required. In order to satisfy such an acoustic impedance density, a conventional matching layer is used as a matching material such as borate glass, chalcogen glass, a composite material in which glass powder is mixed with epoxy resin, and epoxy resin, acrylic resin etc. as matching layer 12. ing. In the case of attaching the matching layer to the transducer 10, a method is used in which, if it is a glass plate, parallel plane polishing is performed with high accuracy to process it into a thin plate and the thin plate is bonded to the transducer 10. In the case of a composite material in which a resin or resin is blended with an appropriate amount of glass fine powder, it is previously formed into a sheet having a desired thickness and bonded with an adhesive, or on the converter 10 or matching layer 1). Methods such as direct casting are used. However, although there is no high frequency in such a conventional method, the presence of the adhesive layer between the transducer and the matching layer is a problem, and the interposition of the adhesive layer significantly increases the performance of the probe. There was a drawback of being lost. In addition, in the case of forming a matching layer with a composite material in which a glass powder is mixed with an organic resin or the organic resin itself, it is difficult to realize a matching layer having a uniform thickness as the matching layer becomes thinner. There is a drawback that the performance of the probe is impaired. Furthermore, when the matching layer is formed of the organic resin and the composite material in which the glass powder is mixed with the organic resin, the thinner the matching layer is, the more easily the bonhole opens and the manufacturing yield of the probe decreases. Therefore, in the conventional manufacturing technology, it is extremely difficult to stably obtain a probe having a matching layer having a thickness of 1100 p or less. Therefore, in a probe which is practically used in a high frequency band, one matching layer is used. The main ones are those having at most two acoustic matching layers. An ultrasonic probe having a triple matching layer which can be broadened more than the double matching layer is not feasible. SUMMARY OF THE INVENTION The object of the present invention is to eliminate the above-mentioned drawbacks of the conventional ultrasonic probe and the method of manufacturing the same and to stably obtain a high-performance broadband ultrasonic probe applicable to high frequency regions. It is (Structure of the Invention) The present invention is formed by laminating a piezoelectric transducer having electrodes on the front and back surfaces and an electrode on the subject side of the piezoelectric transducer, and forming a quarter wavelength of the resonant frequency of the piezoelectric transducer And a plurality of acoustic matching layers having a thickness corresponding to the thickness of the conductive matching layer, a conductive film is formed at 01-05-2019 2 the boundary of each acoustic matching layer, and the other acoustic matching layers are formed directly on the electrodes of the piezoelectric transducer An acoustic matching layer is formed by electrophoresis on an electrode on the subject side of an ultrasonic probe characterized in that a conductive layer is formed inside the matching layer, and a piezoelectric transducer having electrodes on the front and back surfaces. Forming a conductive film on the acoustic matching layer, and electrodepositing on the conductive film an acoustic matching layer thinner than a thickness corresponding to a quarter wavelength of the resonance frequency of the piezoelectric transducer Forming a conductive layer on the acoustic matching layer, and forming sound on the conductive layer Forming a matching layer by an electrodeposition coating method and finally forming an acoustic matching layer having a thickness corresponding to the quarter wavelength, which is a method for manufacturing an ultrasonic probe . (Detailed Description of Configuration) The ultrasonic probe according to the present invention is based on electrodeposition technology to form a precisely controlled uniform matching layer by including the adjustment step of the acoustic matching layer. Solves the problems of the conventional ultrasonic probe and its manufacturing technology. FIG. 1 is a perspective view showing an example of an ultrasonic probe according to the present invention. The structure and the manufacturing method will be described in detail with reference to the drawings. In FIG. 1, 20 is a piezoelectric ceramic transducer, 24 is a backing, and 25 and 26 are electrodes formed on the front and back surfaces of the piezoelectric ceramic plate by a method such as baking, sputtering, vapor deposition or plating. An acoustic matching layer 21 is formed by applying a potential to the electrode 25 and performing electrophoresis. An apparatus for forming an acoustic matching layer is shown in FIG. The method of forming the low acoustic matching layer 21 (in this case, borosilicate glass) will be described with reference to FIG. In order to carry out the electrophoresis method, the piezoelectric transducer 20 is placed in a tank 35 containing slurry 34, and a DC voltage is applied to the electrode 25 by a DC power source 36 to apply glass particles. The slurry 4 for electrophoresis may be, for example, a mixture liquid of ethyl alcohol, polyvinyl butyral and water, in which a borosilicate glass fine powder is sufficiently uniformly dispersed by a homogenizer. The tank 35 containing the slurry 4 is stirred using a stirrer 37 so that the slurry 4 becomes uniform, and a DC voltage is applied between the electrode 25 and the counter electrode 32. As a result, a uniform glass fine powder layer is formed on the surface of the electrode 25. After that, an acoustic matching layer of glass can be formed by heat-treating an object comprising a piezoelectric ceramic transducer and a glass fine powder layer at a high temperature of 500 ° C to 900 ° C. Glass, in particular, borate glass is about twice as fast as an organic resin in sound velocity, and it is easy to realize an optimum matching layer thickness by controlling the time or voltage in the electrophoresis method. In addition, since the thickness of glass can be controlled by polishing, it is also possible to realize an optimum thickness by planeparallel polishing. In the case of an ultrasonic probe having three acoustic matching layers as shown in FIG. 1, the specific acoustic impedance (the product of density and sound velocity) is 10 × IO '˜15 × 10 @ kg as the material of the acoustic matching layer. Preferred materials are 01-05-2019 3 borate, borate glass, borate glass and the like. After the acoustic matching layer 21 is formed by the electrophoresis method and the subsequent heat treatment as described above, a high DC voltage is applied to the electrodes 25.26 to impart piezoelectricity to the piezoelectric ceramic plate 20. A conductive layer 27m is provided on the surface by a method such as plating, evaporation or sputtering, and the acoustic matching layers 22a, 22b, 23a, 23b are sequentially formed by an electrodeposition coating method. That is, reference numeral 22 & is an acoustic matching layer formed by applying a potential to the conductive layer 27 m by electrodeposition coating. As shown in FIG. 1, in the case of an ultrasonic probe having three acoustic matching layers, the material of the matching layer 22a has an intrinsic acoustic impedance value of 3.0 × 10 ′ to 4.5 × 10′kq / co. The material of the east is preferable, and in this electrodeposition coating method, an inorganic resin can be uniformly dispersed in an organic resin, using an organic resin such as a phenol resin or an epoxy resin as a matrix. In addition, as an inorganic fine particle, graf eye), TtO, and BN. AIN, Al, O, etc. can be used. After electrodeposition of the matching layer 22b for a little less than the time required to obtain the desired thickness, the matching layer 21 which is a viscous fluid is completely solidified by heat treatment. Furthermore, conductive @ 28 & made of AJ, Ni, Ag, Au, etc. is formed sufficiently thin on the surface of the solidified matching layer 22 & by evaporation, sputtering or plating, and the film thickness of the matching layer 22 a is measured. . Then, a potential is applied to the conductive film 28a based on the measured value so as to obtain an optimum thickness, and the matching layer 22b having the same acoustic impedance as the matching layer 21a is formed in the same manner. Only then can the thickness of the acoustic matching layer consisting of 22 & and 22b be made to match the design value with high precision. That is, in order to achieve the optimum thickness of the matching layer in one electrodeposition coating method, the speed of sound of the organic resin as the matrix is extremely slow compared to inorganic substances such as glass and porcelain, so it is necessary to As the thickness becomes thinner, it requires much skill and considerable skill, and in the present invention, the function of adjusting the thickness of the matching layer is provided so that an ordinary worker can realize the optimum thickness. Next, the conductive film 27b is formed thinner than the matching layer 22b sufficiently by sputtering, evaporation or plating on the surface of the solidified acoustic matching layer 22b, and the matching layer 23a, the conductive film 28a and the matching layer 23b are sequentially formed in the same manner. Do. As a material of the matching layers 23m and 23b, the intrinsic acoustic impedance is 1.degree. A urethane resin of 1 × 10 'kg / ld · 鴬, an epoxy resin, and the like are preferable. When the conductive films 27m, 27b, 28m and 28b are used as electrodes for shielding, they can block external noise coming into the converter 20 from the living body (subject) side, which has an S / N ratio Contribute to improvement. The conductive films 27a, 27b, 28a and 28b are matching layers 21 and 22a. 01-05-2019 4 It should be formed sufficiently thinner than the matching layers 21, 22m, 22b, 23a, 23b so as not to impede the operation of 22b, 23a, 23b. Here, the electrodeposition technique will be briefly described. The coating method 5 is a method in which a substrate to be coated and a counter electrode are dipped in a water-based paint, and a DC current is passed between the two electrodes to coat the substrate in a pneumatic manner. Here, a cationic electrodeposition paint will be described as an example. In the water-based paint, a resin to be a water-soluble matrix is dissolved, and further, inorganic fine particles to be a filler in the coating film are dispersed. (Of course, electrodeposition coating is possible without inorganic particles. ) When the substrate and the counter electrode are immersed in such a paint, and a cationic electrodeposition paint is applied with a direct current voltage with the substrate being negative and the counter electrode being positive, a chemical reaction occurs on the surface of the substrate, and the coating film Resin and filler for formation are deposited. The amount of resin and filler to be deposited can be controlled by the applied voltage and current for 1 hour, the paint film thickness can be arbitrarily controlled, and it is possible to uniformly attach on the surface of the object without pinholes. In a conventional electrodeposition paint, it can be washed with water after electrodeposition and heated to cure the resin to form a uniform coating film. On the other hand, there are anionic electrodeposition paints as well as cationic electrodeposition paints as an electrodeposition paint, in which case a uniform coating film can be similarly formed by connecting the object to be coated positive and the counter electrode negative. it can. That is, according to the manufacturing method of the present invention, firstly, in the electrodeposition coating method, inorganic fine particles can be uniformly dispersed in the organic resin, and furthermore, the blending degree of the inorganic fine particles can be controlled over a considerably wide range. it can. Since the acoustic impedance naturally changes as the blending degree of the inorganic fine particles changes, it is possible to easily realize a matching layer having an ideal acoustic impedance as designed. Second, the thickness of the acoustic matching layer can be easily controlled by adjusting at least one of the factors of electrodeposition time, voltage and current at the time of electrodeposition. In particular, the probe according to the present invention has an advantage that the thickness of the acoustic matching layer can be finely adjusted due to its structure, and an optimum thickness of the acoustic matching layer can be realized with high accuracy. Third, since the matching layer formed by the electrophoresis method and the electrodeposition coating method is gradually thickened so as to deposit snow as in deposition and sputtering, the matching layer should be formed as thin as possible. In particular, it can be said that the method is extremely effective for realizing an ultrasonic probe in a high frequency band. Fourth, no pinholes occur in the matching layer as a characteristic of electrodeposition. (If pinholes occur during electrodeposition, the organic resin and the filler are deposited so as to completely block the pinholes. 5.) The fifth advantage is that the matching layer can be formed without interposing an adhesive layer. Therefore, according to the present invention, a high performance ultrasonic probe can be obtained not only in an ordinary ultrasonic probe having a 01-05-2019 5 center frequency in the 2 MHz to 7.5 MHz band but also in a high frequency band of 10 MHz or more. EXAMPLE An ultrasonic probe for an IJ near array having a center frequency of 15 MHz and having two acoustic matching layers shown in FIG. 1 will be described as an example of an ultrasonic probe according to the present invention. In this embodiment, the piezoelectric transducer 20 made of pbTiOm-based piezoelectric ceramic was used, and an Au / Cu vapor deposition electrode having a thickness of 3000 × was used for each of the electrodes 25 and 26U. The matching layer 21 is formed in a large number by depositing fine borate glass powder uniformly on the surface of the electrode 25 by electrophoresis, and then performing heat treatment at 800 ° C. for 10 minutes. The measured value of the specific acoustic impedance (defined by the product of density and sound velocity) of the matching layer 21 was 13.8 × 10 ′ kg / n / set. After polarization treatment of the transducer 20, a conductive film 27 瓢 of 2000 A thick is formed on the surface of the matching layer 21 by evaporation, and the specific acoustic impedance 4. An acoustic matching layer 22 'having I X 10' k4 / nl- '& was formed. After the matching layer 22a was cured by heat treatment at 150 ° C. for 2 hours, 2000 Å thick AJ was deposited to form the conductive film 28m, and the matching layer 22b was formed using the same material as the matching layer 22a. Since the thickness of the matching layer 22a was 96g6 of a quarter wavelength for the resonance frequency of 15 MHz of the measurement result converter, the remaining 4% of the matching layer 22b was formed. Both of the matching layers 22m and 22b were made of a composite material in which an appropriate amount of 0.5 μm particle size A and O 8 were uniformly dispersed with an epoxy resin as a matrix. Next, an Aj conductive film 27b having a thickness of 200 OA is vapor-deposited on the surface of the matching layer 22b, and it is made of an acoustic matching layer 23m, 23b and AI having 9 / nlplexus at an acoustic impedance density 195X 10 @ by the electrodeposition coating method. A conductive film 28b was formed. Similarly, the thickness of the matching layer 23m + 23b was adjusted to be a quarter wavelength with respect to the resonant frequency of 15 MHz of the converter. The thickness of the matching layer 22m + 22b was 4 bpm, and the thickness of the matching layer 23m + 23b was 33 μm. It has an extremely wide band characteristic of 90 g6 at the time of water load in the relative bandwidth of the prototyped ultrasonic probe, and the ripple in the pass band is also less than i, s dB. Furthermore, as a result of evaluating this probe using a gel-like sample having the same acoustic impedance density and ultrasonic attenuation coefficient as a living body, a distance resolution of 0.51 ff or less is easily obtained, and an S / 'N ratio Was also good. (Effects of the Invention) According to the present invention as described above, a highly accurate acoustic matching layer can be realized without interposing an adhesive layer, thereby obtaining a high performance ultrasonic probe which can be used in a high frequency region. Can. [0002] Brief description of the drawings 01-05-2019 6 [0003] 1 shows an example of an ultrasonic probe according to the present invention, FIG. 2 shows an example of an apparatus for electrodeposition coating, and FIG. 3 shows an example of a conventional ultrasonic probe. Figure. In the figure, 10.20 is a piezoelectric ceramic transducer, 11 ° 12.21.22 m, 22 b, 23 m, 23 b is an acoustic matching layer, 13.24 is backing, 14.1 5.25, 26 is an electrode, 27 a = 27. b * 28 m28 b: conductive film, 32: counter electrode, 34: slurry, 35: bath, 36: DC power supply, 37: star 2 ° 01-05-2019 7
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