JP5131012B2 - Manufacturing method of multilayer piezoelectric element - Google Patents

Description

The present invention relates to a method of manufacturing a multilayer piezoelectric element comprising an organic piezoelectric body of sheet-shaped organic piezoelectric material stacking a plurality.

  Ultrasound generally refers to sound waves of 16000 Hz or higher, and can be examined non-destructively, harmlessly, and in real time, so that it is applied to various fields such as defect inspection and disease diagnosis. . For example, an ultrasound that scans the inside of the subject with ultrasound and images the internal state of the subject based on a reception signal generated from the reflected wave (echo) of the ultrasound coming from inside the subject. There is a diagnostic device. This ultrasonic diagnostic apparatus is smaller and less expensive for medical use than other medical imaging apparatuses, has no radiation exposure such as X-rays, is highly safe, and has a blood effect using the Doppler effect. It has various features such as the ability to display flow. For this reason, the ultrasonic diagnostic apparatus includes a circulatory system (eg, coronary artery of the heart), a digestive system (eg, gastrointestinal), an internal system (eg, liver, pancreas, and spleen), and a urinary system (eg, kidney and bladder). Widely used in obstetrics and gynecology.

  In this ultrasonic diagnostic apparatus, an ultrasonic probe that transmits and receives ultrasonic waves (ultrasound signals) to a subject is used. This ultrasonic probe uses a piezoelectric phenomenon to generate an ultrasonic wave by mechanical vibration based on an electric signal transmitted, and to generate a reflected wave of the ultrasonic wave caused by an acoustic impedance mismatch inside the subject. The piezoelectric element is configured to receive and generate a received electrical signal.

  In recent years, for example, from the viewpoint of improving diagnostic accuracy, it has been desired to increase the definition (high resolution) of ultrasonic images, and for this reason, it is desired to increase the bandwidth of piezoelectric elements. In addition, it is possible to reduce so-called speckle noise and artifacts by increasing the bandwidth of the piezoelectric element. For example, Patent Document 1 discloses a backing block, a first transducer made of piezoelectric ceramic (PZT) formed on the backing block, and a second made of piezoelectric ceramic (PZT) formed on the first transducer. A transducer, a matching layer formed on the second transducer, a third transducer made of piezoelectric polymer (PVDF) formed on the matching layer, and an acoustic window formed on the third transducer layer; A multi-layer transducer configured with a is disclosed. The multilayer transducer having such a configuration transmits, for example, first and second ultrasonic signals in a frequency band centered on 2 MHz and 4.25 MHz by the second transducer, and 4 MHz and 4 by the first and third transducers. Each echo signal in a frequency band centered on each second harmonic of 8.5 MHz can be received, and thus a wide band is achieved by using a piezoelectric polymer.

On the other hand, the reflected wave of the ultrasonic wave generated due to the mismatch of acoustic impedance inside the subject is absorbed and attenuated by the subject while propagating through the subject, so the signal level (acoustic energy) is small. . For this reason, it is desired to increase the receiving sensitivity of the piezoelectric element. As a method for increasing the receiving sensitivity of the piezoelectric element, for example, there is a method in which the piezoelectric element has a multilayer structure. For example, Patent Document 2 and Patent Document 3 disclose a laminated piezoelectric actuator in which piezoelectric ceramics are laminated. In manufacturing this multilayer piezoelectric actuator, first, a slurry is prepared by mixing piezoelectric ceramic powder with an organic binder and a solvent, and a piezoelectric ceramic raw sheet is prepared from this slurry by a doctor blade method or the like. Next, an internal electrode conductor mainly composed of silver and palladium is printed on one surface of the piezoelectric ceramic sheet. Next, a plurality of piezoelectric ceramic raw sheets on which the internal electrode conductors are printed are stacked and pressed by a press. Next, the laminated piezoelectric ceramic raw sheet is debindered at 500 ° C., for example, and then fired at 1200 ° C., for example, to produce a sintered body block. Then, after the sintered body block is mechanically cut to a desired size, an external electrode conductor is formed on the cut surface and a lead wire is connected to manufacture a laminated piezoelectric actuator.
JP 2007-029745 A Japanese Patent Laid-Open No. 04-179285 Japanese Patent Laid-Open No. 06-252469

  By the way, in order to increase the reception sensitivity of the organic piezoelectric element, a laminated piezoelectric element including an organic piezoelectric body in which a plurality of organic piezoelectric materials in the form of a film (plate, layer, film) is laminated by the method for producing a laminated piezoelectric actuator If it is going to manufacture, since there exists a comparatively high temperature baking process, it will be difficult to manufacture this laminated piezoelectric element.

  In addition, it is necessary to consider that the internal electrode in the multilayer piezoelectric element may be peeled off due to aging due to mechanical ultrasonic vibration or the like.

The present invention is an invention made in view of the above circumstances, and its object is to provide a method of manufacturing a multilayer piezoelectric element comprising an organic piezoelectric body of sheet-shaped organic piezoelectric material stacking a plurality.

As a result of various studies, the present inventor has found that the above object is achieved by the present invention described below. That is, in one aspect that written to the present invention, on one main surface of a sheet-like organic piezoelectric layer composed of an organic piezoelectric material, a first electrode layer forming step of forming an electrode layer by a vapor phase method, the organic piezoelectric An adhesive layer forming step of forming an adhesive layer by applying an adhesive on the other main surface of the layer; the organic piezoelectric layer produced by the first electrode layer forming step and the adhesive layer forming step; A plurality of first organic piezoelectric sheets including an electrode layer and the adhesive layer are bonded to each other so that an adhesive layer in one organic piezoelectric sheet and an electrode layer in another organic piezoelectric sheet of the plurality of organic piezoelectric sheets are bonded to each other. A first laminating step for laminating, and a pressurizing and heating treatment step for pressurizing and heating the organic piezoelectric body on which the first organic piezoelectric sheet produced by the first laminating step is laminated. Features . In the method for manufacturing a laminated piezoelectric element described above, preferably, a second electrode layer forming step of forming electrode layers on both main surfaces of a sheet-like organic piezoelectric layer made of an organic piezoelectric material by a vapor phase method; The organic piezoelectric layer produced by the second electrode layer forming step and the both electrodes on the adhesive layer exposed to the outside in the organic piezoelectric body obtained by laminating the plurality of organic piezoelectric sheets produced by the first laminating step And a second lamination step of laminating a second organic piezoelectric sheet comprising a layer.

  In the method of manufacturing an organic piezoelectric element having such a configuration, when a plurality of organic piezoelectric sheets are stacked, they can be stacked with an adhesive forming an adhesive layer. Therefore, the multilayer piezoelectric element manufacturing method having such a configuration can be manufactured at a relatively low temperature, and provides a multilayer piezoelectric element including an organic piezoelectric body in which a plurality of sheet-like organic piezoelectric materials are stacked. Is possible.

In the method for producing the above-described laminated piezoelectric element, the organic piezoelectric material, characterized in that it comprises a copolymer comprising vinylidene fluoride as a monomer. Further, in the above-described method for manufacturing a laminated piezoelectric element, the organic piezoelectric material is a polyurea formed by vapor phase condensation polymerization of a monomer having two or more isocyanate groups and a monomer having two or more amine groups. It is characterized by containing a polymer. According to the above configuration, the organic piezoelectric material has a relatively large electromechanical coupling constant (piezoelectric effect), and the organic piezoelectric sheet composed of such an organic piezoelectric material transmits an electric signal and an ultrasonic signal to each other. It can be converted efficiently and is suitable as a piezoelectric body. Therefore, according to the said structure, the lamination type piezoelectric element which can convert an electrical signal and an ultrasonic signal more efficiently mutually can be provided .

In the above-described method for manufacturing a laminated piezoelectric element, the adhesive is an epoxy adhesive .

In the method for producing these aforementioned multilayer piezoelectric element, said in the pressurizing and heating process is any value in the range from applied pressure is 1kPa to 100 GPa, the warming temperature is 200 ° C. from 20 ° C. The pressurizing and heating treatment time is any value in the range from 1 minute to 72 hours.

  According to the above configuration, it is possible to reduce deterioration of piezoelectric characteristics in the organic piezoelectric body. The pressurizing pressure, heating temperature, and pressurizing / heating time are appropriately selected according to the organic piezoelectric material within the above ranges. Also, under relatively severe conditions where the pressurization pressure is high and the heating temperature is high, the pressurization and heating treatment time is relatively short, while the pressurization pressure is low and the heating temperature is low. Under relatively loose conditions, the pressure heating treatment time is relatively long.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the lamination type piezoelectric element containing the organic piezoelectric material which laminated | stacked several sheet-like organic piezoelectric materials is provided .

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted. Further, in this specification, when referring generically, it is indicated by a reference symbol without a suffix, and when referring to an individual configuration, it is indicated by a reference symbol with a suffix.
(Embodiment)
FIG. 1 is a diagram illustrating an external configuration of an ultrasonic diagnostic apparatus according to an embodiment. FIG. 2 is a block diagram illustrating an electrical configuration of the ultrasonic diagnostic apparatus according to the embodiment. FIG. 3 is a perspective view illustrating a configuration of an ultrasonic probe in the ultrasonic diagnostic apparatus according to the embodiment. FIG. 4 is a cross-sectional view showing one element among a plurality of stacked piezoelectric elements constituting the ultrasonic probe of the embodiment.

  As shown in FIGS. 1 and 2, the ultrasonic diagnostic apparatus S transmits an ultrasonic wave (first ultrasonic signal) to a subject such as a living body (not shown) and reflects the ultrasonic wave reflected by the subject. The ultrasonic probe 2 that receives the reflected wave (echo, second ultrasonic signal) is connected to the ultrasonic probe 2 via the cable 3 and connected to the ultrasonic probe 2 via the cable 3. By transmitting an electrical signal transmission signal (transmission electrical signal), the ultrasound probe 2 transmits the first ultrasound signal to the subject, and the inside of the subject received by the ultrasound probe 2 An ultrasonic image that images the internal state of the subject as an ultrasound image based on a received signal (received electrical signal) of an electrical signal generated by the ultrasound probe 2 according to the second ultrasound signal coming from The diagnostic apparatus main body 1 is provided.

  For example, as shown in FIG. 2, the ultrasonic diagnostic apparatus main body 1 includes an operation input unit 11, a transmission unit 12, a reception unit 13, an image processing unit 14, a display unit 15, and a control unit 16. Configured.

  The operation input unit 11 inputs data such as a command for instructing start of diagnosis and personal information of a subject, for example, and is an operation panel or a keyboard provided with a plurality of input switches, for example.

  The transmission unit 12 is a circuit that supplies a transmission signal of an electrical signal to the ultrasonic probe 2 via the cable 3 under the control of the control unit 16 and causes the ultrasonic probe 2 to generate a first ultrasonic signal. is there. The transmission unit 12 includes, for example, a high voltage pulse generator that generates a high voltage pulse.

  The receiving unit 13 is a circuit that receives a reception signal of an electrical signal from the ultrasound probe 2 via the cable 3 under the control of the control unit 16, and outputs the reception signal to the image processing unit 14. For example, in order to compensate for transmission loss (transmission loss) of the cable 3, the reception unit 13 delays the reception signal amplified by the amplification circuit 131 that amplifies the reception signal with a predetermined amplification factor set in advance. A receiving circuit 132 that performs processing, phasing addition processing, and the like. In the case of generating an ultrasonic image by a filtering process for reducing speckle noise or a harmonic imaging technique, the signal processed by the receiving circuit 132 is higher order. A reception processing circuit 133 that performs harmonic imaging processing and the like that separates harmonics and fundamental waves, and an analog-digital conversion circuit (ADC circuit) that converts a signal processed by the reception processing circuit 133 from an analog signal to a digital signal 134 and the like.

  The image processing unit 14 is a circuit that generates an image (ultrasonic image) representing the internal state in the subject based on the reception signal received and processed by the receiving unit 13 under the control of the control unit 16. The image processing unit 14 displays, for example, an ultrasonic image on the display unit 15 and a DSP (Digital Signal Processor) 141 that generates an ultrasonic image of the subject based on the reception signal received and processed by the reception unit 13. A digital-analog conversion circuit (DAC circuit) 142 for converting a signal processed by the DSP 141 from a digital signal to an analog signal is provided. The DSP 141 includes a B-mode processing circuit, a Doppler processing circuit, a color mode processing circuit, a space synthesis circuit, a frequency synthesis circuit, and the like, and can generate so-called B-mode images, Doppler images, and color mode images.

  The image processing unit 14 receives an ultrasonic signal having a frequency band substantially the same as the frequency band of the first ultrasonic signal as a second ultrasonic signal, and receives the received ultrasonic wave at the receiving unit 13. Based on the received reception signal, the image processing unit 14 Although an ultrasonic image may be generated, in the present embodiment, from the viewpoint of obtaining a higher-accuracy ultrasonic image, the image processing unit 14 uses the harmonic imaging technology to receive the receiving unit 13. An ultrasonic image of the subject is generated based on the received signal received in step (1).

  In this harmonic imaging technology, the side lobe level is small compared to the level of the fundamental frequency component, the S / N ratio (signal to noise ratio) is improved, the contrast resolution is improved, and the beam width is increased by increasing the frequency. The lateral resolution improves, the sound pressure is small and the fluctuation in sound pressure is small at short distances, so that multiple reflections are suppressed. Compared to the case of using the fundamental wave, it has various advantages such as a greater depth speed.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2001-286472, the harmonic imaging technique is roughly classified into two methods, a filter method and a phase inversion method (pulse inversion method). This filter method is a method in which a fundamental wave component and a harmonic component are separated by a harmonic detection filter, only the harmonic component is extracted, and an ultrasonic image is generated from the harmonic component. Further, this phase inversion method transmits first and second transmission signals whose phases are successively inverted in the same direction, and first and second reception signals corresponding to the first and second transmission signals are transmitted. In this method, a harmonic component is extracted by addition and an ultrasonic image is generated from the harmonic component. Although the fundamental wave components in the first and second received signals are inverted in phase, the second harmonic component of the harmonic, for example, is in phase, so by adding the first and second received signals This second harmonic component is extracted.

  In the image processing unit 14, for example, a harmonic component is extracted from the received signal by a filter method, and an ultrasonic image of the subject is generated using a harmonic imaging technique based on the extracted harmonic component. Further, for example, the image processing unit 14 extracts a harmonic component from the received signal by the phase inversion method, and generates an ultrasonic image of the subject based on the extracted harmonic component using a harmonic imaging technique.

  The display unit 15 is a device that displays an ultrasonic image of the subject generated by the image processing unit 14 under the control of the control unit 16. The display unit 15 is, for example, a display device such as a CRT display, LCD (liquid crystal display), organic EL display, or plasma display, or a printing device such as a printer.

  The control unit 16 includes, for example, a microprocessor, a storage element, and peripheral circuits thereof, and the ultrasonic probe 2, the operation input unit 11, the transmission unit 12, the reception unit 13, the image processing unit 14, and a display. It is a circuit that performs overall control of the ultrasound diagnostic apparatus S by controlling the unit 15 according to the function.

  The ultrasonic probe (ultrasonic probe) 2 is a device that transmits a first ultrasonic signal into a subject and receives a second ultrasonic signal coming from within the subject based on the first ultrasonic signal. . For example, as shown in FIGS. 3 and 4, the ultrasonic probe 2 is laminated on a plate-like acoustic braking member 21 (21 </ b> A, 21 </ b> B, 21 </ b> C) and one main surface of the acoustic braking member 21. A plurality of inorganic piezoelectric elements 22, a plurality of intermediate layers 23 respectively stacked on the plurality of inorganic piezoelectric elements 22, a plurality of organic piezoelectric elements 24 respectively stacked on the plurality of intermediate layers 23, and the plurality of these And an acoustic matching layer and an acoustic lens (not shown) laminated on the organic piezoelectric element 24.

  The acoustic matching layer is a member that matches the acoustic impedance of the inorganic piezoelectric element 22 and the organic piezoelectric element 24 with the acoustic impedance of the subject. The acoustic matching layer may be composed of a single layer or may be composed of a plurality of layers. For example, in the case where the reception frequency band is widened, the acoustic matching layer is preferably composed of a plurality of layers. The acoustic lens is a member that converges ultrasonic waves transmitted toward the subject, and has a shape that bulges in an arc shape. Note that the acoustic matching layer and the acoustic lens may be integrally formed.

  The acoustic braking member 21 is made of a material that absorbs ultrasonic waves (ultrasonic absorber), and mainly absorbs ultrasonic waves radiated from the inorganic piezoelectric element 22 toward the acoustic braking member 21. The acoustic braking member 21 preferably has a sufficient thickness with respect to the wavelength of the ultrasonic wave to be used in order to keep the acoustic characteristics of the inorganic piezoelectric element 22 good by sufficiently attenuating the ultrasonic wave. . The acoustic braking member 21 mechanically supports the inorganic piezoelectric element 22 and acoustically applies braking so as to shorten the pulse waveform of the first ultrasonic signal. The acoustic braking member 21 is generally also called an acoustic load member, a backing layer, a damper layer, or an acoustic absorbing member. Examples of the material of the acoustic braking member 21 include a material obtained by mixing an acoustic scattering powder in a resin such as an epoxy resin. In such a material, the attenuation factor of the ultrasonic wave can be increased by the acoustic scattering powder. The acoustic scattering powders are tungsten (W), molybdenum (Mo), silver (Au), platinum (Pt), palladium (Pd), indium (In), scandium (Sc), yttrium (Y) and tantalum (Ta). In this embodiment, tungsten is used because of cost and availability. As shown in FIG. 4, the acoustic braking member 21 has a plurality of conductor wires 27, one end of which is connected to one electrode of the inorganic piezoelectric element 22, penetrating in the stacking direction. Embedded in the ultrasonic absorber.

The inorganic piezoelectric element 22 includes an inorganic piezoelectric material, and converts an electrical signal and an ultrasonic signal to each other by using a piezoelectric phenomenon. The inorganic piezoelectric element 22 includes, for example, electrode layers 222 and 223 on opposite surfaces of an inorganic piezoelectric body 221 made of an inorganic piezoelectric material. One electrode layer 222 in the inorganic piezoelectric element 22 is electrically connected to the conductor wire 27 of the acoustic braking member 21 as a signal line. Examples of the inorganic piezoelectric material of the inorganic piezoelectric body 221 include so-called PZT, quartz, lithium niobate (LiNbO ₃ ), potassium niobate tantalate (K (Ta, Nb) O ₃ ), barium titanate (BaTiO ₃ ), and tantalum. Lithium oxide (LiTaO ₃ ) and strontium titanate (SrTiO ₃ ). The thickness of the inorganic piezoelectric body 221 in the inorganic piezoelectric element 22 is appropriately set depending on, for example, the frequency of ultrasonic waves to be transmitted, the type of inorganic piezoelectric material, and the like.

  The plurality of inorganic piezoelectric elements 22 stacked on the acoustic braking member 21 are arranged in m rows × n columns in two directions that are linearly independent in a plan view with a predetermined interval therebetween, for example, in two directions orthogonal to each other. Two-dimensionally arranged in an array. m and n are positive integers. Since the plurality of intermediate layers 23 and the plurality of organic piezoelectric elements 24 are stacked on the plurality of inorganic piezoelectric elements 22, they are two-dimensionally arranged in an array of m rows × n columns. From the viewpoint of reducing crosstalk between the inorganic piezoelectric elements 22, it is preferable that the gap generated by the predetermined interval is filled with an ultrasonic absorber.

  The intermediate layer (buffer layer) 23 is a member for laminating the inorganic piezoelectric element 22 and the organic piezoelectric element 24. In the present embodiment, the intermediate layer 23 is a member that matches the acoustic impedances of the inorganic piezoelectric element 22 and the organic piezoelectric element 24.

  The organic piezoelectric element 24 includes an organic piezoelectric material, and converts a second ultrasonic signal coming from within the subject based on the first ultrasonic signal into a received electric signal by using a piezoelectric phenomenon. . In this embodiment, as shown in FIG. 4, the organic piezoelectric element 24 includes a sheet-like organic piezoelectric layer 241 (241-2 to 241-7) made of an organic piezoelectric material and an organic piezoelectric layer 241 (2412-2). 241-7), the electrode layer 242 (242-2 to 242-7) formed on one main surface and the organic piezoelectric layer 241 (241-2 to 241-7) formed on the other main surface. An organic piezoelectric body 24a in which a plurality of organic piezoelectric sheets 24 (24-2 to 24-7) including layers 243 (243-2 to 243-7) are stacked is provided. The organic piezoelectric element 24 is laminated on the organic piezoelectric body 24a and formed on both main surfaces of the sheet-like organic piezoelectric layer 241-1 and the organic piezoelectric layer 241-1 made of an organic piezoelectric material. An organic piezoelectric sheet 24-1 including electrode layers 242-1 and 244 is provided.

  In the present embodiment, the organic piezoelectric element 24 is configured by laminating seven organic piezoelectric sheets 24 (24-1 to 24-7). The plurality of organic piezoelectric sheets 24 (24-1 to 24-7) include the adhesive layer 243 and one of the other organic piezoelectric sheets 24 of the plurality of organic piezoelectric sheets 24 (24-1 to 24-7). The electrode layers 242 in the piezoelectric sheet 24 are bonded and laminated with an adhesive of the adhesive layer 243 so as to be bonded to each other. For example, the organic piezoelectric sheet 24-7 and the organic piezoelectric sheet 24-6 are formed such that the adhesive layer 243-7 of the organic piezoelectric sheet 24-7 and the electrode layer 242-6 of the organic piezoelectric sheet 24-6 are bonded to each other. The organic piezoelectric sheet 24-7 is laminated by being adhered by the adhesive of the adhesive layer 243-7 of the organic piezoelectric sheet 24-7. Further, for example, the organic piezoelectric sheet 24-6 and the organic piezoelectric sheet 24-5 are formed such that the adhesive layer 243-6 of the organic piezoelectric sheet 24-6 and the electrode layer 242-5 of the organic piezoelectric sheet 24-5 are bonded to each other. The organic piezoelectric sheet 24-6 is laminated by being bonded with an adhesive of the adhesive layer 243-6 of the organic piezoelectric sheet 24-6. Thus, each organic piezoelectric sheet 24 (24-7 to 24-1) is adhered to the adhesive layer 243 (243-7 to 243) of the organic piezoelectric sheet 24 (24-7 to 24-2) positioned below in the stacking direction. The electrode layer 242 (242-6 to 242-1) of the organic piezoelectric sheet 24 (24-6 to 24-1) positioned on the upper side in the stacking direction is bonded by the adhesive of 2). The adhesive of the adhesive layer 243 includes a binder having chemical affinity for the organic piezoelectric material of the organic piezoelectric layer 241 and chemical affinity for the material of the electrode layer 242. The organic piezoelectric material of the organic piezoelectric layer 241 and the adhesive of the adhesive layer 243 will be described later.

  Then, external electrode sheets 26-1 and 26-2 on which external electrode patterns 28 and 29 are formed are respectively attached to both side surfaces of the laminate in which the inorganic piezoelectric element 22, the intermediate layer 23, and the organic piezoelectric element 24 are laminated by an adhesive. Bonded and fixed. One of the external electrode sheets 26-1 and 26-2, for example, the external electrode sheet 26-1 functions as a signal line for extracting a signal from the organic piezoelectric element 24, and the external electrode pattern 28 is the external electrode pattern 28. A plurality of sheets penetrates the sheet from one main surface to the other main surface in the thickness direction, and each part of the external electrode pattern 28 includes an electrode layer 244 of the plurality of organic piezoelectric sheets 24-1, an organic piezoelectric element, respectively. An electrode layer 242-2 interposed between the sheet 24-2 and the organic piezoelectric sheet 24-3, an electrode layer 242-4 interposed between the organic piezoelectric sheet 24-4 and the organic piezoelectric sheet 24-5, and It is electrically connected to the electrode layer 242-6 interposed between the organic piezoelectric sheet 24-6 and the organic piezoelectric sheet 24-7 by being pressure-bonded along with the adhesive fixing. The other of the external electrode sheets 26-1 and 26-2, for example, the external electrode sheet 26-2 functions as a ground line for grounding the inorganic piezoelectric element 22 and the organic piezoelectric element 24, and the external electrode pattern thereof. 29, a plurality of parts of the external electrode pattern 29 penetrate through the sheet from one main surface to the other main surface in the thickness direction, and each part of the external electrode pattern 29 is respectively an organic piezoelectric sheet 24-1. Electrode layer 242-1 interposed between the organic piezoelectric sheet 24-2 and the organic piezoelectric sheet 24-4, electrode layer 242-2 interposed between the organic piezoelectric sheet 24-4 and the organic piezoelectric sheet 24-5. To the electrode layer 242-5 interposed between the organic piezoelectric sheet 24-6, the electrode layer 242-7 of the organic piezoelectric sheet 24-7, and the other electrode layer 223 of the inorganic piezoelectric element 22. It is electrically connected by being crimped with a constant. The organic piezoelectric element 24 in which seven organic piezoelectric sheets 24 (24-1 to 24-7) are stacked has an electrode layer 244, an electrode layer 242-1, an electrode layer 242-2, and an electrode layer 242-3 from the outermost surface. , Electrode layer 242-4, electrode layer 242-5, electrode layer 242-6, and electrode layer 242-7, but with the above configuration, the external electrode pattern of the external electrode sheet 26-1 every other electrode layer 244 28, and every other electrode layer 242-1 is electrically connected to the external electrode pattern 29 of the external electrode sheet 26-2.

  In the example shown in FIG. 4, the number of organic piezoelectric sheets 24 (24-1 to 24-7) to be stacked is seven, but the number of layers may be arbitrary. For example, a desired sensitivity can be obtained. It is set appropriately.

  In such a configuration, since the inorganic piezoelectric element 22 and the organic piezoelectric element 24 have a two-layer structure, one of them is used for an ultrasonic transmission unit that transmits an ultrasonic signal, and the other is used for an ultrasonic signal. It can be used for an ultrasonic receiving unit for receiving. For this reason, one of them can be made more suitable for transmission, and the other can be made more suitable for reception, enabling optimization, and more accurate images. Can be obtained. For example, in this embodiment, the inorganic piezoelectric element 22 capable of increasing the transmission power is used as the ultrasonic transmission unit, and the organic piezoelectric element 24 has a characteristic capable of receiving ultrasonic waves over a relatively wide frequency. Is used as an ultrasonic receiver. Therefore, the ultrasonic probe 2 having such a configuration can transmit the first ultrasonic signal of the fundamental wave with relatively large power, and can obtain a higher harmonic component of the second ultrasonic signal. It is possible to suitably receive the harmonic component of the second ultrasonic signal. And since the organic piezoelectric element 24 is a lamination | stacking type | mold, it can receive the harmonic component of a 2nd ultrasonic signal with higher sensitivity. For this reason, in particular, since the ultrasonic probe 2 having such a configuration can receive the harmonic component of the second ultrasonic signal with high sensitivity, an ultrasonic image can be obtained by the harmonic imaging technique described above. It is suitable for the ultrasonic diagnostic apparatus S to be formed.

  3 and 4, since the inorganic piezoelectric element 22 and the organic piezoelectric element 24 are laminated, the ultrasonic probe 2 can be miniaturized. In addition, an organic piezoelectric element 24 as an ultrasonic receiving unit is disposed between the first and second ultrasonic signal transmitting / receiving surfaces (the surface of the acoustic lens not shown) and the inorganic piezoelectric element 22 as an ultrasonic transmitting unit. Therefore, it is possible to reduce the reception noise and improve the S / N ratio.

  In the ultrasonic probe 2 having such a configuration, a transmission signal of an electric signal input to the ultrasonic probe 2 from the transmission unit 12 via the cable 3 is transmitted to each of the plurality of inorganic piezoelectric elements 22. The signal is input via each of the plurality of conductor lines 27. Each inorganic piezoelectric element 22 converts this electric signal into an ultrasonic signal by utilizing a piezoelectric phenomenon, and transmits this ultrasonic signal. Then, when the ultrasonic probe 2 is applied to the subject, the ultrasonic signal generated by each inorganic piezoelectric element 22 is transmitted into the subject as a first ultrasonic signal. On the other hand, each organic piezoelectric element 24 receives a second ultrasonic signal coming from within the subject based on the first ultrasonic signal, and uses the piezoelectric phenomenon to convert the received second ultrasonic signal into an electrical signal. It converts and outputs this electric signal. This electrical signal is output via the external electrode pattern of the external electrode sheet 26-1. This electrical signal is output from the ultrasound probe 2 to the receiving unit 13 of the ultrasound diagnostic apparatus body 1 via the cable 3.

  In such a configuration, when a plurality of organic piezoelectric sheets 24 (24-1 to 24-7) are stacked, they can be stacked with an adhesive that forms the adhesive layer 243 (243-2 to 243-7). It is. For this reason, in such a configuration, it is possible to manufacture at a relatively low temperature, and it is possible to provide a stacked piezoelectric element including an organic piezoelectric body 24a in which a plurality of sheet-like organic piezoelectric materials are stacked.

  The ultrasonic probe 2 having such a configuration is manufactured as follows. FIG. 5 is a diagram for explaining a method of manufacturing an organic piezoelectric element in the multilayer piezoelectric element of the embodiment.

  In FIG. 5, first, a sheet made of an organic piezoelectric material to be an organic piezoelectric layer 241 (241-2 to 241-7) is prepared, and on one main surface of the sheet, for example, a chemical vapor phase method or a physical layer is prepared. The electrode layer 242 (242-2 to 242-7) is formed by a vapor phase method such as a vapor phase method (first electrode layer forming step). The thickness of the sheet is appropriately set depending on, for example, the frequency of ultrasonic waves to be received, the type of organic piezoelectric material, and the like. The thickness of the sheet is usually any value in a range from about 1 μm to about 1 mm, and is, for example, about 20 μm in the present embodiment. In the chemical vapor deposition method (CVD method), for example, a raw material gas containing a component of the electrode layer 242 is supplied into a reaction tube made of stainless steel, quartz, or the like, and the surface of the sheet or the surface of the sheet heated or heated in the reaction tube. In this method, a thin film is deposited as the electrode layer 242 by a chemical reaction in a gas phase. Examples of the chemical vapor phase method include a thermal CVD method, a plasma CVD method, a photo CVD method, an epitaxial CVD method, and an atomic layer CVD method. The physical vapor phase method (PVD method) is a method in which a thin film is deposited as an electrode layer 242 on the sheet in a gas phase by a physical method. Examples of physical vapor phase methods include resistance heating vapor deposition, electron beam vapor deposition, molecular beam epitaxy, ion plating (ion plating), ion beam deposition, and sputtering. The material of the electrode layer 242 is preferably aluminum, copper, nickel, zinc, tin, silver, platinum, gold, palladium, and alloys thereof. Alternatively, the material of the electrode layer 242 may be a conductive organic material. Particularly preferably, high energy atoms (argon or ions thereof) are collided with a metal disk (target) such as aluminum in a high vacuum, and metal atoms are struck out from the disk, and the struck metal atoms are ejected from the sheet. The aluminum metal electrode layer is formed by depositing and depositing on the surface in layers. The thickness of the electrode layer 242 is appropriately set. For example, the thickness is set to any value in a range from about 0.1 μm to about 5 μm.

  Next, on the other main surface of the sheet, by applying an adhesive containing a binder having chemical affinity for the organic piezoelectric material and chemical affinity for the electrode layer material, Adhesive layer 243 (243-2 to 243-7) is formed (adhesive layer forming step). Prior to the application of the adhesive, a pretreatment may be performed in order to increase (enhance) the adhesive strength on the surface of the sheet. Examples of the pretreatment include corona discharge, laser treatment, flame treatment, plasma treatment, and polishing treatment. The pretreatment is to chemically treat the surface of the sheet to increase the adhesive strength by forming functional groups such as OH group (hydroxyl group), carboxyl group, aldehyde group and amino group on the surface of the sheet. Is possible. Alternatively, the pretreatment makes it possible to increase the adhesive strength by physically treating the surface of the sheet by making the surface of the sheet uneven and improving the bite (anchoring effect) of the adhesive.

  Next, a plurality of first organic piezoelectric sheets 24 (24-2 to 24-24) including the organic piezoelectric layer 241, the electrode layer 242, and the adhesive layer 243 produced by the first electrode layer forming step and the adhesive layer forming step described above. −7) is such that the adhesive layer 242 in one organic piezoelectric sheet 24 of the plurality of organic piezoelectric sheets 24 (24-2 to 24-7) and the electrode layer 243 in another organic piezoelectric sheet 24 are bonded to each other. Are stacked (first stacking step).

  Next, a sheet made of an organic piezoelectric material to be the organic piezoelectric layer 241-1 is prepared, and electrodes are formed on both main surfaces of the sheet by a vapor phase method such as a chemical vapor phase method or a physical vapor phase method. Layers 242-1 and 244 are formed (second electrode layer forming step). Here, the thickness of the sheet, the vapor phase method, and the material and thickness of the electrode layers 242-1 and 244 are the same as those in the first electrode layer forming step described above.

  Next, on the adhesive layer 243-2 exposed to the outside in the organic piezoelectric body 24 a in which the plurality of organic piezoelectric sheets 24 (24-2 to 24-7) prepared by the first stacking step are stacked (the outermost organic piezoelectric layer). On the sheet 24-2, a second organic piezoelectric sheet 24-1 including the organic piezoelectric layer 241-1 produced by the second electrode layer forming step and both electrode layers 242-1 and 244 is laminated (first). 2 lamination process).

  Next, the organic piezoelectric body 24a on which the second organic piezoelectric sheet 24-1 produced in the second lamination step is laminated is pressurized and heated (pressurization and heating treatment step), and the organic piezoelectric element 24 is manufactured. Is done. Preferably, in this pressurizing and heating treatment step, the pressurizing pressure is any value in the range from about 1 kPa to about 100 GPa, and the heating temperature is any value in the range from about 20 ° C. to about 200 ° C. The pressure heating treatment time is any value in the range from about 1 minute to about 72 hours. By executing the pressurizing and heating process under such conditions, it is possible to reduce the deterioration of the piezoelectric characteristics of the organic piezoelectric element 24. Here, the pressurizing pressure, the heating temperature, and the pressurizing and heating treatment time are appropriately selected according to the organic piezoelectric material within the above range. Also, under relatively severe conditions where the pressurization pressure is high and the heating temperature is high, the pressurization and heating treatment time is relatively short, while the pressurization pressure is low and the heating temperature is low. Under relatively loose conditions, the pressure heating treatment time is relatively long. Moreover, when the pressurizing pressure is relatively high, the adhesive layer 243 (243-2 to 243-7) is extremely thin. As is generally known, for example, even a polymer that melts at 80 ° C. can be sufficiently endured without melting if it is heated for a very short time, for example, about 1 minute.

  Next, in parallel with the manufacture of the organic piezoelectric element 24 described above, or before or after the manufacture of the organic piezoelectric element 24 described above, a plurality of inorganic piezoelectric elements 22 laminated on the acoustic braking member 21 are known manufacturing methods. Manufactured by.

  More specifically, for example, first, an inorganic piezoelectric sheet made of a flat inorganic piezoelectric material having a predetermined thickness, which becomes the inorganic piezoelectric body 221, is prepared. A metal film to be the electrode layers 222 and 223 is formed on both main surfaces over substantially the entire surface by, for example, screen printing, vapor deposition, sputtering, or the like.

  Next, the inorganic piezoelectric sheet on which the two metal films are formed is laminated via an adhesive on the flat acoustic braking member 21 in which a plurality of conductor wires 27 are embedded so as to penetrate in the laminating direction, and bonded and fixed. Is done. Next, grooves (gap, gap, gap, slit) in the stacking direction are formed in the inorganic piezoelectric sheet by, for example, a dicing saw until the acoustic braking member 21 is exposed. The grooves are arranged in two directions so as to constitute a plurality of inorganic piezoelectric elements 22 in a two-dimensional array arranged in m rows × n columns in two directions that are linearly independent in plan view, for example, in two directions orthogonal to each other. A plurality are formed. The inorganic piezoelectric element 22 has, for example, a rectangular shape in plan view, and the size thereof is appropriately set depending on, for example, resolution. Through these steps, a plurality of inorganic piezoelectric elements 22 laminated on the acoustic braking member 21 are manufactured.

  Next, the plurality of organic piezoelectric elements 24 manufactured as described above are bonded and fixed onto the plurality of inorganic piezoelectric elements 22 via the intermediate layer 23, respectively. When the intermediate layer 23 is made of an epoxy resin, the intermediate layer 23 can be used as an adhesive.

  Next, external electrode sheets 26-1 and 26-2 having external electrode patterns 28 and 29 formed on both side surfaces of the laminated body in which the inorganic piezoelectric element 22, the intermediate layer 23, and the organic piezoelectric element 24 are laminated are bonded with an adhesive. Bonded and fixed.

  Next, an acoustic matching layer and an acoustic lens (not shown in FIGS. 3 and 4) are formed on the organic piezoelectric element 24, and the ultrasonic probe 2 having the structure shown in FIGS. 3 and 4 is manufactured.

  In such a configuration, when a plurality of organic piezoelectric sheets 24 (24-1 to 24-7) are stacked, they can be stacked with an adhesive that forms the adhesive layer 243 (243-2 to 243-7). It is. For this reason, in such a configuration, it is possible to manufacture at a relatively low temperature, and it is possible to provide a stacked piezoelectric element including an organic piezoelectric body 24a in which a plurality of sheet-like organic piezoelectric materials are stacked.

  In the ultrasonic diagnostic apparatus S configured as described above, for example, when an instruction to start diagnosis is input from the operation input unit 11, a transmission signal of an electrical signal is generated by the transmission unit 12 under the control of the control unit 16. The generated electrical signal transmission signal is supplied to the ultrasonic probe 2 via the cable 3. The electric signal transmission signal is, for example, a voltage pulse repeated at a predetermined cycle. By supplying the transmission signal of the electric signal, each of the plurality of inorganic piezoelectric elements 22 expands and contracts in the thickness direction, and ultrasonically vibrates according to the transmission signal of the electric signal. By this ultrasonic vibration, the plurality of inorganic piezoelectric elements 22 radiate ultrasonic waves (first ultrasonic signals) through the intermediate layer 23, the organic piezoelectric element 24, the acoustic matching layer, and the acoustic lens. For example, when the ultrasonic probe 2 is in contact with the subject, the first ultrasonic signal is transmitted from the ultrasonic probe 2 to the subject. As the fundamental frequency of the fundamental wave in the first ultrasonic signal, generally any value in a range from about 2 MHz to about 25 MHz is selected.

  Note that the ultrasound probe 2 may be used in contact with the surface of the subject, or may be used by being inserted into the subject, for example, being inserted into a body cavity of a living body. .

  The first ultrasonic signal transmitted to the subject is reflected by one or a plurality of boundary surfaces having different acoustic impedances inside the subject, and becomes an ultrasonic reflected wave (second ultrasonic signal). The second ultrasonic signal includes not only the frequency (fundamental fundamental frequency) component of the transmitted first ultrasonic signal but also a harmonic frequency component that is an integral multiple of the fundamental frequency. For example, second harmonic components such as twice, three times, and four times the fundamental frequency, third harmonic components, fourth harmonic components, and the like are also included. This second ultrasonic signal is received by the ultrasonic probe 2. The harmonic frequency is preferably 2 to 6 times the fundamental frequency. More specifically, the second ultrasonic signal is received by a plurality of organic piezoelectric elements 24 via the acoustic lens and the acoustic matching layer, and mechanical vibrations are converted into electric signals by the organic piezoelectric elements 24. Is taken out as a received signal. The extracted reception signal of the electrical signal is received from the ultrasonic probe 2 via the cable 3 by the receiving unit 13 of the ultrasonic diagnostic apparatus body 1. The reception unit 13 performs signal processing on the input reception signal and outputs the signal to the image processing unit 14.

  Here, in the above description, the first ultrasonic signal is sequentially transmitted from each inorganic piezoelectric element 22 toward the subject, and the second ultrasonic signal reflected by the subject is received by each organic piezoelectric element 24.

  Then, under the control of the control unit 16, the image processing unit 14 generates an ultrasonic image of the subject based on the reception signal received by the reception unit 13 from the time from transmission to reception, the reception intensity, and the like, and the display unit 15 displays the ultrasonic image of the subject generated by the image processing unit 14 under the control of the control unit 16. Note that the image processing unit 14 may generate an ultrasonic image of the subject by the above-described harmonic imaging technique.

  Thus, in this embodiment, the ultrasonic probe 2 provided with the laminated piezoelectric element is provided. In such an ultrasonic probe 2, the frequency band in transmission and reception is relatively widened, and the reception sensitivity is also relatively high. In the present embodiment, an ultrasonic diagnostic apparatus S using the ultrasonic probe 2 provided with the multilayer piezoelectric element is provided. In such an ultrasonic diagnostic apparatus S, an ultrasonic image of a subject is relatively high definition (high resolution), and so-called speckle noise and artifacts are relatively reduced.

  Next, the organic piezoelectric material will be described.

(Organic piezoelectric material)
The organic piezoelectric material in the organic piezoelectric layer 241 of the organic piezoelectric sheet 24 is a copolymer containing 60 mole percent or more of vinylidene chloride monomer units, or a monomer having two or more isocyanate groups and a monomer having two or more amine groups. A polyurea polymer formed by vapor phase condensation polymerization. By using such an organic piezoelectric material, the organic piezoelectric material has a relatively large electromechanical coupling constant (piezoelectric effect), and the organic piezoelectric sheet 24 composed of such an organic piezoelectric material is capable of A sound wave signal can be converted more efficiently with each other, which is suitable as a piezoelectric body.

  More specifically, the organic piezoelectric layer 241 of the organic piezoelectric sheet 24 is preferably a copolymer containing vinylidene fluoride, which is a polymer piezoelectric film, as a monomer, and particularly preferably a polyvinylidene fluoride / trifluoroethylene copolymer. . The molecular weight of the raw material polymer generally becomes a piezoelectric film having a low tensile elastic modulus, which has the flexibility and flexibility inherent to the polymer as the molecular weight increases. When a polymer piezoelectric material having a melt flow rate at 230 ° C. of 0.02 g / min or less, more preferably 0.01 g / min or less in P (VDF-TrFE) and / or P (VDF-TeFE) is used. It becomes a polymer piezoelectric film having a low tensile elastic modulus, and a highly sensitive organic piezoelectric sheet 24 is obtained. Here, VDF represents vinylidene fluoride, TrFE represents ethylene trifluoride, and TeFE represents tetrafluoroethylene.

  On the other hand, in the case of poly (vinylidene fluoride / 3-ethyl fluoride) (abbreviated as P (VDF-TrFE)), the electromechanical coupling constant (piezoelectric effect) in the thickness direction varies depending on the copolymerization ratio. Preferably, the range of the copolymerization ratio of vinylidene fluoride is 60 mol% to 99 mol%, but it depends on the method of using the organic binder used when the inorganic piezoelectric element 22 and the organic piezoelectric element 24 are overlapped. The value varies. More preferably, the range of the copolymerization ratio of vinylidene fluoride is 65 mol% to 85 mol%. You may make vinylidene fluoride 65 mol%-85 mol%, and may contain 1 mol%-15 mol% of perfluoroalkyl vinyl ether, perfluoroalkoxyethylene, perfluorohexaethylene etc. as a different monomer.

  In addition, the organic piezoelectric layer 241 of the organic piezoelectric sheet 24 is a urea resin having a urea bonding group. First, low molecular weight polymerization is performed using only a diisocyanate compound or a diisocyanate compound and a diamine compound as raw material monomers. A combination (prepolymer) can be used.

  Examples of the diisocyanate compound as a raw material monomer include methylene diphenyl 4,4′-diisocyanate, 3,3′-dimethyldiphenyl-4,4′-diisocyanate, o-dianisidine diisocyanate, methylene bis (4- Isocyanato-3-methylbenzene), methylenebis (4-isocyanato-2-methylbenzene), methylenebis (o-chlorophenylisocyanate), 5-chloro-2,4-toluene diisocyanate, 4,4'-diphenylmethane Diisocyanate (MDI), 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 3,5-diisocyanate benzotrifluoride, Bis (4-isocyanatophenyl) ether, dicyclohexylmeta -4,4'-diisocyanate, norbornane diisocyanate methyl, p-phenylene diisocyanate, p-xylene diisocyanate, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate, 2,6- One or two or more of naphthalene diisocyanate, trans-1,4-cyclohexyl diisocyanate, isophorone diisocyanate 1,3-bis (isocyanatomethyl) benzene and the like can be used in combination.

  As raw material monomers, diamine compounds, (a) diamine components include 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diamino-3,3'-dimethyldiphenylmethane, 3,3 ' -Dimethoxy-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl, 2, 2 ', 5,5'-tetrachloro-4,4'-diaminobiphenyl, 4,4'-methylene-bis (2-chloroaniline), 4,4'-diaminodiphenyl sulfone, 2,7-diaminofluorene, One or two or more of 4,4′-diamino-p-terphenyl, 1,3-diamino-5-cyanobenzene, etc. are mixed and used. It is possible.

  (B) Diisocyanate components include methylene diphenyl 4,4'-diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, o-dianisidine diisocyanate, methylene bis (4-isocyanate). Nate-3-methylbenzene), methylene bis (4-isocyanato-2-methylbenzene), methylene bis (o-chlorophenyl isocyanate), 5-chloro-2,4-toluene diisocyanate, 4,4'-diphenylmethane di Isocyanate (MDI), 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 3,5-diisocyanate benzotrifluoride, bis (4-Isocyanatophenyl) ether, dicyclohexylmethane-4,4'-di Sodiumate, norbornane diisocyanate methyl, p-phenylene diisocyanate, p-xylene diisocyanate, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate, 2,6-naphthalene diisocyanate, trans-1 , 4-cyclohexyl diisocyanate, isophorone diisocyanate 1,3-bis (isocyanatomethyl) benzene, etc. can be used alone or in combination.

  Preferable polyurea includes polyurea by the combination of the above (a) / (b). 4,4'-diaminodiphenylmethane / 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 4,4'-diaminodiphenylmethane / o-dianisidine diisocyanate, 4,4'-diaminodiphenylmethane / methylenebis (4-isocyanato-2-methylbenzene), 4,4'-diaminodiphenylmethane / 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-diaminodiphenylmethane / 2,4-toluene diisocyanate ( 2,4-TDI), 4,4'-diaminodiphenylmethane / 2,6-toluene diisocyanate (2,6-TDI), 4,4'-diaminodiphenylmethane / bis (4-isocyanatophenyl) ether, 4,4'-diaminodiphenylmethane / p-phenylene diisocyanate 4,4'-diaminodiphenylmethane / 1,5-naphthalene diisocyanate, 4,4'-diaminodiphenyl ether / 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 4,4'-diaminodiphenyl ether / O-dianisidine diisocyanate, 4,4'-diaminodiphenyl ether / methylenebis (4-isocyanato-2-methylbenzene), 4,4'-diaminodiphenyl ether / 4,4'-diphenylmethane diisocyanate (MDI) 4,4′-diaminodiphenyl ether / 2,4-toluene diisocyanate (2,4-TDI), 4,4′-diaminodiphenyl ether / 2,6-toluene diisocyanate (2,6-TDI), 4 , 4'-Diaminodiphenyl ether / bis (4-isocyanate Ether phenyl) ether, 4,4'-diaminodiphenyl ether / p-phenylene diisocyanate, 4,4'-diaminodiphenyl ether / 1,5-naphthalenediisocyanate, 4,4'-diaminodiphenyl ether / 1,3-bis ( Isocyanatomethyl) benzene, 4,4'-diamino-3,3'-dimethyldiphenylmethane / 3,3'-dimethyldiphenyl-4,4'-diisocyanate 4,4'-diamino-3,3'-dimethyl Diphenylmethane / o-dianisidine diisocyanate, 4,4'-diamino-3,3'-dimethyldiphenylmethane / methylenebis (4-isocyanato-2-methylbenzene), 4,4'-diamino-3,3'- Dimethyldiphenylmethane / 4,4'-diphenylmethane diisocyanate ( MDI), 4,4'-diamino-3,3'-dimethyldiphenylmethane / 2,4-toluene diisocyanate (2,4-TDI), 4,4'-diamino-3,3'-dimethyldiphenylmethane / 2 , 6-Toluene diisocyanate (2,6-TDI), 4,4'-diamino-3,3'-dimethyldiphenylmethane / bis (4-isocyanatophenyl) ether, 4,4'-diamino-3, 3'-dimethyldiphenylmethane / p-phenylenediisocyanate, 4,4'-diamino-3,3'-dimethyldiphenylmethane / 1,5-naphthalene diisocyanate, 3,3'-dimethoxy-4,4'-diamino Biphenyl / 3,3′-dimethyldiphenyl-4,4′-diisocyanate, 3,3′-dimethoxy-4,4′-diaminobiphenyl o-dianisidine diisocyanate, 3,3'-dimethoxy-4,4'-diaminobiphenyl / methylenebis (4-isocyanato-2-methylbenzene), 3,3'-dimethoxy-4,4'-diaminobiphenyl / 4,4'-diphenylmethane diisocyanate (MDI), 3,3'-dimethoxy-4,4'-diaminobiphenyl / 2,4-toluene diisocyanate (2,4-TDI), 3,3'- Dimethoxy-4,4'-diaminobiphenyl / 2,6-toluene diisocyanate (2,6-TDI), 3,3'-dimethoxy-4,4'-diaminobiphenyl / bis (4-isocyanatophenyl) Ether, 3,3'-dimethoxy-4,4'-diaminobiphenyl / p-phenylene diisocyanate, 3,3'-dimethoxy-4,4 -Diaminobiphenyl / 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-diaminobiphenyl / 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 3,3'- Dimethyl-4,4'-diaminobiphenyl / o-dianisidine diisocyanate, 3,3'-dimethyl-4,4'-diaminobiphenyl / methylenebis (4-isocyanato-2-methylbenzene), 3,3 ' -Dimethyl-4,4'-diaminobiphenyl / 4,4'-diphenylmethane diisocyanate (MDI), 3,3'-dimethyl-4,4'-diaminobiphenyl / 2,4-toluene diisocyanate (2, 4-TDI), 3,3'-dimethyl-4,4'-diaminobiphenyl / 2,6-toluene diisocyanate (2,6-TDI), 3 3,3'-dimethyl-4,4'-diaminobiphenyl / bis (4-isocyanatophenyl) ether, 3,3'-dimethyl-4,4'-diaminobiphenyl / p-phenylene diisocyanate, 3,3 '-Dimethyl-4,4'-diaminobiphenyl / 1,5-naphthalene diisocyanate, 4,4'-methylene-bis (2-chloroaniline) / 3,3'-dimethyldiphenyl-4,4'-di Isocyanate, 4,4'-methylene-bis (2-chloroaniline) / o-dianisidine diisocyanate, 4,4'-methylene-bis (2-chloroaniline) / methylenebis (4-isocyanate-2- Methylbenzene), 4,4'-methylene-bis (2-chloroaniline) / 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-me Ren-bis (2-chloroaniline) / 2,4-toluene diisocyanate (2,4-TDI), 4,4'-methylene-bis (2-chloroaniline) / 2,6-toluene diisocyanate ( 2,6-TDI), 4,4'-methylene-bis (2-chloroaniline) / bis (4-isocyanatophenyl) ether, 4,4'-methylene-bis (2-chloroaniline) / p- Examples include phenylene diisocyanate, 4,4'-methylene-bis (2-chloroaniline) / 1,5-naphthalene diisocyanate, 1,3-diamino-5-cyanobenzene / 2,6-naphthalene diisocyanate. be able to.

  In the polymerization, the polymerization is preferably performed at 60 ° C. or lower. In particular, the temperature is preferably in the range of 5 ° C to 35 ° C. Since it is preferable not to increase the degree of polymerization, the temperature may be low. However, if the temperature is too low, cooling equipment and cooling power are required, which is not preferable. On the other hand, when the temperature is 60 ° C. or higher, the polymerization proceeds and the viscosity increases, so that it is difficult to apply and the solvent to be dissolved is limited. Since the reaction time depends on the reaction amount and temperature, it needs to be adjusted appropriately. However, it is preferable to adjust to a short time from the viewpoint of productivity.

  In the organic piezoelectric layer 241 of the organic piezoelectric sheet 24, the poling (polarization treatment) is preferably performed until the polarization inversion occurs, and the polarization inversion is obtained by applying the poling electric field with the direction reversed repeatedly. The formation of such a polarization distribution state varies depending on the temperature, and requires several tens of thousands to several hundreds of thousands of times at room temperature (room temperature 23 ° C.). When the organic piezoelectric element 24 is used for reception, a corona treatment of 1 mW to 1 kW / cm 2 may be performed at normal pressure when the organic piezoelectric element 24 is formed into a thin film.

  Next, the adhesive will be described.

(adhesive)
The adhesive in the adhesive layer 243 of the organic piezoelectric sheet 24 includes a binding material having a chemical affinity for the organic piezoelectric material and a chemical affinity for the material of the electrode layer 242. The adhesive preferably has high (strong) adhesive strength and is difficult to peel off by ultrasonic vibration. An example of such an adhesive is an epoxy adhesive.

  As this epoxy adhesive, for example, a mixed type using two kinds of an epoxy main agent and an epoxy curing agent can be selected. Examples of the main epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, liquid epoxy resin, rubber-modified epoxy resin, and urethane-modified epoxy resin.

  Examples of the epoxy curing agent include aliphatic amines, alicyclic amines, aromatic amines, mercaptans, ketimines, polyamides, polyamide amines, and special polyamide amines. These main epoxy resins may be used alone or in combination of several, and the same applies to epoxy curing agents. Further, the combination of the main epoxy resin and the epoxy curing agent is not particularly limited.

  Particularly preferred epoxy adhesives are exemplified below, but are not limited thereto.

  Examples of the bisphenol type epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenol type epoxy resin, and cresol type epoxy resin. Examples of the bisphenol A type epoxy resin include Epicoat 825, Epicoat 827, Epicoat 828, Epicoat 834, Epicoat 1002, Epicoat 1004, Epicoat 1009 (each trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), Epototo YD128, Epototo YD011, Epototo YD012, Epototo YD014, Epototo YD017, Epototo YD019, Epototo YD020 (each trade name, manufactured by Tohto Kasei Co., Ltd.), Epicron 840, Epicron 850, Epicron 855, Epicron 860, Epicron 1050, Epicron 3050, Epicron 4050, Epicron 4050 Name, manufactured by Dainippon Ink & Chemicals, Inc.), DER330, DER331, DER332, DER662, DER662U, DE 663U (each trade name, manufactured by Dow Chemical Co., Ltd.), Araldite CY205, Araldite CY230, Araldite CY232, Araldite CY221, Araldite GY257, Araldite GY252, Araldite GY255, Araldite GY250, Araldite GY260, Araldite 70G (Each product name, manufactured by Ciba-Geigy Corporation).

  As an example, bisphenol F-type epoxy resin is commercially available under trade names such as Epicoat 806, Epicoat 807 (manufactured by Yuka Shell Epoxy), Epototo YDF170 (manufactured by Tohto Kasei Co., Ltd.), Epicron 830 (manufactured by Dainippon Ink and Chemicals). What is being done is mentioned.

  Examples of the phenol type epoxy resin and the cresol type epoxy resin include Epicoat 152, Epicoat 154 (each trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), Epototo YDPN-638, Epototo YDCN701, Epototo YDCN702, Epototo YDCN703 (each trade name, DEN431, DEN438, DEN439 (each trade name, manufactured by Dow Chemical Co., Ltd.) and the like.

  An example of a resorcinol type epoxy resin is Denacol EX-201 (trade name, manufactured by Nagase Kasei Kogyo Co., Ltd.). An example of a hydroquinone type epoxy resin is Denacol EX-203 (trade name, manufactured by Nagase Kasei Kogyo Co., Ltd.). ) And the like.

  Examples of aromatic amine-type epoxy resins include tetraglycidyldiaminodiphenylmethane, triglycidylaminophenol, diglycidylaniline, diglycidylorthotoluidine, and the like. Commercially available products of tetraglycidyldiaminodiphenylmethane include Sumi-epoxy ELM434 ( As commercial products of trade name, manufactured by Sumitomo Chemical Co., Ltd., Epototo YH434L, Epototo YH434 (trade name, manufactured by Tohto Kasei Kogyo Co., Ltd.), Araldite MY720 (trade name, manufactured by Ciba Geigy Co., Ltd.), and triglycidylaminophenol are commercially available, Sumi-epoxy ELM100 , Sumi-Epoxy ELM120 (each trade name, manufactured by Sumitomo Chemical Co., Ltd.), GAN (trade name, manufactured by Nippon Kayaku Co., Ltd.) as diglycidyl aniline, GOT (trade name, Nippon Kayaku Co., Ltd.) as diglycidyl orthotoluidine Ltd.) and the like.

  Examples of the aromatic glycidyl ester type epoxy resin include Denacol EX-721 (trade name, manufactured by Nagase Kasei Kogyo Co., Ltd.), which is o-phthalic acid diglycidyl ester, and Denacol EX-711, which is terephthalic acid diglycidyl ester (product). Name, manufactured by Nagase Kasei Kogyo Co., Ltd.), AK-601 (trade name, manufactured by Nippon Kayaku Co., Ltd.) which is a nuclear hydride of o-phthalic acid diglycidyl ester, and the like. As an example of the naphthalene type epoxy resin, Epicron HP-4032H (trade name, manufactured by Dainippon Ink & Chemicals, Inc.), which is 1,6-dihydroxynaphthalenediglycidyl ether, can be given.

  As an example, the aromatic epoxy resin is Epicoat YX4000 (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), which is 4,4′-dihydroxy-3,3 ′, 5,5′-biphenyldiglycidyl ether, 4,4 Epicoat YL6121H (trade name, manufactured by Yuka Shell Epoxy Co., Ltd.), which is a mixture of '-dihydroxy-3,3', 5,5'-biphenyldiglycidyl ether and 4,4'-dihydroxybiphenyl diglycidyl ether .

  Examples of the aliphatic epoxy resin and / or the alicyclic epoxy resin include commercially available products Denacol EX-921, Denacol EX-931, which is polypropylene glycol diglycidyl ether, Denacol EX-922, which is polytetramethylene glycol diglycidyl ether. , Denacol EX-211, which is neopentyl glycol diglycidyl ether, 1, Denacol EX-212 which is 1,6-hexanediol diglycidyl ether (each trade name, manufactured by Nagase Kasei Kogyo Co., Ltd.), polyhydric alcohol ether type epoxy resin Epicron 705, Epicron 707, Epicron 720, Epicron 725 (each trade name, manufactured by Dainippon Ink & Chemicals, Inc.), Rica Resin HBE, which is a nuclear hydride of bisphenol A type epoxy resin (trade name, Shin Nihon Ri ), Glycidylated Rica Resin BEO-60E (trade name, manufactured by Shin Nippon Rika Co., Ltd.) added with ethylene oxide to bisphenol A type epoxy resin, and glycidylated Rica Resin DME-100 (Trade name, manufactured by Shin Nippon Chemical Co., Ltd.), Plaxel GL61, Plaxel GL62, Plaxel G101, Plaxel G102, Plaxel G105, Plaxel G401, Plaxel G402, each of which has caprolactone added to the secondary hydroxyl group of bisphenol A type epoxy resin , Daicel Chemical Industries, Ltd.).

  Examples of the epoxy resin curing agent include dicyandiamide alone or dicyandiamide and a curing accelerator such as 3- (3,4-dichlorophenyl) -1,1-dimethylurea, 3- (4-chlorophenyl) -1,1-dimethylurea. And a combination of derivatives such as 3-phenyl-1,1-dimethylrarea.

  Moreover, another hardening | curing agent and hardening accelerator can be further mix | blended as needed. Examples of the curing agent include diaminodiphenyl sulfone and diaminodiethylbenzene, and examples of the curing accelerator include boron trifluoride monoethylamine complexes, boron trichloride monoethylamine and other boron trifluoride complexes, and boron trichloride complexes. And the like.

  In the epoxy resin composition, other epoxy resins, toughening resins, fillers, colorants, and the like can be blended within a range that does not impair the performance. Examples of toughening resins that can be included in the epoxy resin composition as desired include reactive elastomers, hiker CTBN-modified epoxy resins, urethane-modified epoxy resins, nitrile rubber-added epoxy resins, and crosslinked acrylic rubber fine particle-added epoxy resins. , Silicone-modified epoxy resins, thermoplastic elastomer-added epoxy resins, and the like.

  In the above-described embodiment, the ultrasonic probe 2 includes the inorganic piezoelectric element 22 as an ultrasonic transmission unit and the organic piezoelectric element 24 as an ultrasonic reception unit. However, the ultrasonic probe 2 transmits and receives ultrasonic waves. It may be configured to include only the organic piezoelectric element 24 as an ultrasonic transmission / reception unit. Further, the organic piezoelectric element 24 may be used as an ultrasonic transmission unit.

Next, examples will be described.
(Example)
Examples of the multilayer piezoelectric element having the above-described configuration will be described below. In the production of the organic piezoelectric sheet 24, first, copolymerized pellets of vinylidene fluoride / ethylene trifluoride (75:25 (mole percent ratio)) are used, and the solvent is stretched by 3 times in the vertical and horizontal directions to obtain 15 cm × A 15 cm square sheet was formed. Next, an electrode layer was formed by performing aluminum vapor deposition on both main surfaces of the square sheet. Next, a normal polarization process was performed on the square sheet in which the electrode layers were formed on both main surfaces, and a square sheet piezoelectric element was manufactured. When the resonance frequency of this polarized square sheet was measured with an oscilloscope (Agilent DSO5012A), the resonance frequency was 7.5 MHz. Next, the electrode layer formed on the other main surface of the square sheet was dissolved and peeled by a conventional method, and a square sheet in which the electrode layer was formed only on one main surface was produced. And six such square sheets were prepared by the same process. Furthermore, separately, one square sheet that does not peel the electrode layer was prepared by omitting the above-described electrode layer peeling step.

  Next, for each of the six square sheets from which the electrode layer was peeled, an araldite of epoxy resin was applied as an adhesive layer on the other main surface from which the electrode layer of the square sheet was peeled off with an adhesive layer thickness of 2 μm. Next, the six square sheets from which the electrode layer has been peeled are laminated so that the adhesive layer of one square sheet and the electrode layer of the other square sheet are joined together, and finally the electrode layer is peeled off. There are no square sheets laminated. Next, the laminate obtained by laminating the seven square sheets was heated and cross-linked at a heating pressure of 120 ° C. for 3 minutes at a pressure of 20 GPa to produce a piezoelectric element having a seven-layer structure.

  Next, a ceramic piezoelectric element was bonded and fixed to the lower part of the seven-layer piezoelectric element via an intermediate layer, and a laminated piezoelectric element was manufactured. This intermediate layer was formed with a regular composition in which tungsten particles were mixed with an araldite resin.

  In the manufacture of this ceramic piezoelectric element, first, PNN (lead nickel niobate), PT (lead titanate) and PZ (lead zirconate) powders are used as the piezoelectric ceramic powder, and the molar ratio thereof is 0.48PNN. : 0.38PT: 0.14PZ. Next, this was mixed using PVB (polyvinyl butyral), made into a slurry, and then coated to prepare a piezoelectric ceramic sheet (green sheet) having a thickness of about 60 μm. Next, a platinum paste containing 18% by volume of the PNN-PT-PZ powder was applied to both main surfaces of the piezoelectric ceramic sheet in an internal electrode shape having a film thickness of about 5 μm by screen printing. . Next, a green sheet with a screen-printed internal electrode is pressure-bonded at a pressure of 40 GPa, held in an electric furnace at 1150 ° C. in an atmosphere in the atmosphere, subjected to baking heat treatment for about 3 hours, and molded. The body was made. Next, this molded body was separated into a 128-element array by a dicing saw manufactured by DISCO, and a ceramic piezoelectric element was manufactured. This ceramic piezoelectric element was bonded to the lower part of the seven-layered piezoelectric element as described above.

  In the examples, a metal conductor paste (platinum paste in this example) containing 18% by volume of powder having the same composition as the piezoelectric ceramic was used as the internal electrode paste on the ceramic piezoelectric element side. Thus, by admixing the powder having the same composition as the piezoelectric ceramic, the adhesion between the piezoelectric ceramic layer and the internal electrode layer can be improved.

  The multilayer piezoelectric element manufactured in this way was incorporated into an ultrasonic probe, and impedance matching was performed and used for an ultrasonic diagnostic apparatus.

  The performance evaluation was performed using an agarose phantom in which stainless needles were sequentially arranged at intervals of 100 nm to 1 mm to a depth of 1 cm to 5 cm. In the experiment, the sensitivity and resolution were evaluated for the 5, 4, 3 layer structure and the single layer structure by sequentially reducing the number of organic piezoelectric sheets in the multilayer piezoelectric element from 7 sheets. Sensitivity is expressed as relative sensitivity with a single layer as 100. As for the resolution, a 100 nm interval is observed at a depth of 3 cm (agarose thickness 3 cm), and when a single layer is used as a reference, a significant improvement in resolution is recognized, and an improvement in resolution is clearly recognized. The case where it was possible was evaluated as excellent. Durability evaluation was performed by reassessing the performance after mounting the ultrasonic probe mounted with the laminated piezoelectric element of this example on the ultrasonic diagnostic apparatus and operating this ultrasonic diagnostic apparatus continuously for 50 hours. It was evaluated by observing the change. Experiment numbers 100 to 104 are evaluations immediately after mounting, and experiment numbers 200 to 204 indicate evaluation (re-evaluation) after the durability test.

  As a reference comparison, seven organic piezoelectric sheets were laminated by using an adhesive. However, in the case without pressure and heating, the electrode interface was broken and could not be measured. Evaluation was impossible.

(Performance evaluation test results)
Test number; Number of layers; Sensitivity; Resolution 100; Single layer; 100 (Standard); Standard 101; Three layers; 130; Good 102; Four layers; 161; Superior 103; Five layers; 192; Superior 104; Seven layers; ; Excellent (Durability evaluation test results)
Experiment number; Laminated structure; Sensitivity; Resolution 100; Single layer; Reference; Reference 200; Single layer; No change; No change 201; Three layers; No change; No change 202; Four layers; No change; No change 203; Layer: No change; No change 204; Seven layers; No change; No change As can be seen from the above test results, the sensitivity increases and the resolution also improves as the number of stacked organic piezoelectric elements increases. Further, no peeling occurs between the stacked layers, and the durability performance is not deteriorated.

  In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

It is a figure which shows the external appearance structure of the ultrasound diagnosing device in embodiment. It is a block diagram which shows the electrical structure of the ultrasonic diagnosing device in embodiment. It is a perspective view which shows the structure of the ultrasound probe in the ultrasound diagnosing device of embodiment. FIG. 3 is a cross-sectional view showing one element among a plurality of stacked piezoelectric elements constituting the ultrasonic probe of the embodiment. It is a figure for demonstrating the manufacturing method of the organic piezoelectric element in the lamination type piezoelectric element of embodiment.

Explanation of symbols

S ultrasonic diagnostic apparatus 1 ultrasonic diagnostic apparatus main body 2 ultrasonic probe 21 acoustic braking member 22 inorganic piezoelectric element 24 organic piezoelectric sheet 24a organic piezoelectric body 241 organic piezoelectric layer 242 electrode layer 243 adhesive layer

Claims (6)

A first electrode layer forming step of forming an electrode layer on one main surface of a sheet-like organic piezoelectric layer made of an organic piezoelectric material by a vapor phase method ;
An adhesive layer forming step of forming an adhesive layer by applying an adhesive on the other main surface of the organic piezoelectric layer ;
Among the plurality of organic piezoelectric sheets, a plurality of first organic piezoelectric sheets comprising the organic piezoelectric layer, the electrode layer, and the adhesive layer produced by the first electrode layer forming step and the adhesive layer forming step. A first laminating step of laminating so that an adhesive layer in one organic piezoelectric sheet and an electrode layer in another organic piezoelectric sheet are bonded to each other ;
Method of fabricating the multilayer piezoelectric element, characterized in that it comprises a pressurizing and heating step of heating with pressurizing the organic piezoelectric body obtained by laminating the first organic piezoelectric sheet produced by the first laminating step . A second electrode layer forming step of forming electrode layers on both principal surfaces of a sheet-like organic piezoelectric layer made of an organic piezoelectric material by a vapor phase method ;
The organic piezoelectric layer and the both electrode layers prepared by the second electrode layer forming step on the adhesive layer exposed to the outside in the organic piezoelectric body in which the plurality of organic piezoelectric sheets prepared by the first lamination step are laminated. A method for producing a laminated piezoelectric element according to claim 1, further comprising: a second laminating step of laminating a second organic piezoelectric sheet comprising : The organic piezoelectric material, manufacturing method of the product layer piezoelectric element according to claim 1 or claim 2, characterized in that it comprises a copolymer comprising vinylidene fluoride as a monomer. The organic piezoelectric material according to claim 1, characterized in that it comprises a polyurea polymer formed by a gas phase method polycondensation of a monomer having a monomer and an amine group with an isocyanate group two or more two or more or A method for manufacturing a multilayer piezoelectric element according to claim 2 . The method for manufacturing a multilayer piezoelectric element according to any one of claims 1 to 4, wherein the adhesive is an epoxy adhesive . In the pressurization and heating treatment step, the pressurization pressure is any value in the range from 1 kPa to 100 GPa, and the warming temperature is any value in the range from 20 ° C to 200 ° C. The method for manufacturing a multilayer piezoelectric element according to any one of claims 1 to 5, wherein the temperature treatment time is any value within a range of 1 minute to 72 hours .

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