JP5338389B2 - Ultrasonic probe manufacturing method, ultrasonic probe, ultrasonic diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an ultrasonic probe capable of reliably establishing electrical connection between each piezoelectric element and an acoustic damper, to provide the ultrasonic probe, and to provide an ultrasonic diagnosis device. <P>SOLUTION: A plurality of through-holes 101 are formed in a surface-to-be-joined 104 of a backing material 100. Each through-hole 101 is filled with a conductive paste to form a columnar conductor 102. An electrode base 103 is formed at an end of each columnar conductor 102 and then polished. A minute protrusion 106 is formed on each electrode base 103 by screen printing. Alternatively, an electrode layer 114 is formed on a surface-to-be-joined 112 of a piezoelectric base material 110 using a silver baking technique. The piezoelectric base material 100 is cut into a grid to form a plurality of piezoelectric elements 115. A gap 116 between each piezoelectric element 115 is filled with a filler to form a division wall 117. Thereafter, the surface-to-be-joined 104, and the surface-to-be-joined 112 to which an adhesive have been applied, are caused to face each other, and the acoustic damper 21 and a piezoelectric part 22 are bonded with each other by applying pressure so that the protrusions 106 stick into the electrode layer 114. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing an ultrasonic probe capable of transmitting and receiving ultrasonic waves, and more particularly to a technique for joining an acoustic braking member and a piezoelectric body provided in an ultrasonic probe.

  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, an ultrasonic diagnostic apparatus includes a circulatory system (for example, coronary artery of the heart), a digestive system (for example, gastrointestinal), an internal system (for example, liver, pancreas, and spleen), and a urinary system (for example, 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. A plurality of piezoelectric elements that receive and generate received electrical signals are provided, and the plurality of piezoelectric elements are, for example, two-dimensionally arranged in an array.

  A member called an acoustic braking member (acoustic load member, backing layer, damper layer, acoustic absorbing member) that absorbs ultrasonic waves is provided on one surface (back surface) of the plurality of piezoelectric elements. A wiring for transmitting and receiving electrical signals is connected to each of the plurality of piezoelectric elements.

  There are the following Patent Documents 1 to 4 as technical documents related to this type of ultrasonic probe.

  In Patent Document 1 below, a plurality of through-holes are formed in a backing material, and signal wires are drawn into the through-holes in a state in which both ends protrude, and in this state, the piezoelectric body and the backing material are bonded with a conductive adhesive. A technique for forming a plurality of vibrator pieces by forming grooves at a depth from the surface side of the piezoelectric body to the backing layer after bonding is disclosed.

  In Patent Document 2, a plurality of piezoelectric vibrators, a plurality of printed circuit boards in which a plurality of signal lines electrically connected to signal electrodes of the piezoelectric vibrators are arranged in a predetermined direction, and a plurality of backing materials are provided. The piezoelectric vibrators are mounted in a row on one end side of the signal lines in the printed boards, and a backing material is installed on the printed boards adjacent to the rows of the piezoelectric vibrators. A technique for manufacturing a two-dimensional array ultrasonic probe in which a plurality of piezoelectric vibrators are arranged in a matrix by stacking the printed circuit boards in the same direction has been proposed.

  Patent Document 3 discloses a process of arranging a plurality of vibrators in a matrix with a certain gap provided on the electrode surface of a common electrode laminated on an acoustic matching layer, and a substrate side laminated on each vibrator. Forming a wall made of a polymer material in the gap in a manner protruding from the electrode to the substrate side (opposite to the acoustic matching layer), and forming a notch at an appropriate position of the wall corresponding to each piezoelectric element And a step of forming a bump connected to the substrate side electrode in the notch, a step of forming the bump on the signal line formed in a matrix on the substrate, and each vibration so that the both bumps are integrated. A technique for manufacturing a two-dimensional array ultrasonic probe through a step of electrically connecting a signal line electrically connected to a substrate and a substrate-side electrode by bonding a child and the substrate is disclosed. .

  Patent Document 4 includes “a mounting board on which a plurality of switching elements corresponding to individual micro-vibrators of the piezoelectric vibrator according to claim 2 are arranged in a one-to-one manner. , Positioning so that the individual micro-vibration body and the switching element overlap the surface direction of the piezoelectric vibrator with the electrode layer sandwiched between the surface of the piezoelectric vibrator on which the electrode layer (I) is formed In addition, the mounting is characterized in that the individual micro-vibration bodies and the switching elements that are overlapped in the plane direction are electrically connected via the electrode layer by overlapping and pressing the mounting substrate and the piezoelectric vibrator. Device. ([Claim 6]) ”.

  Further, in Patent Document 4 below, “an etching resist layer R2 is formed which covers a region on the surface of the piezoelectric vibrating member 1 where a fine electrode is to be patterned. Next, the metal thin film M is covered with the etching resist layer R2. When the etching resist layer R2 is removed after selectively removing the non-existing region, the fine electrode 22 is selectively patterned on the surface of the piezoelectric vibrating member 1 in the region where the etching resist layer R2 is formed. An array 2 is formed. "

JP-A-7-131895 JP 2001-309493 A Japanese Patent Laid-Open No. 5-123317 JP 2004-88056 A

  Conventionally, a method of simply joining each piezoelectric element (vibrator) and an acoustic braking member has been employed. In the case of this method, when the piezoelectric body and the acoustic braking member completely face each other in parallel at a predetermined interval, electrical connection between each piezoelectric element and the acoustic braking member can be ensured.

  However, in reality, when each piezoelectric element is joined to the acoustic braking member, the piezoelectric element is inclined or partially lifted, resulting in variations in the gap between each piezoelectric element and the acoustic braking member. It was difficult to connect to the electrode on the acoustic braking member side.

  The present invention has been made in order to solve the above-described problems, and an ultrasonic probe manufacturing method and ultrasonic wave capable of reliably ensuring electrical connection between each piezoelectric element and an acoustic braking member. An object is to provide a probe and an ultrasonic diagnostic apparatus.

According to a first aspect of the present invention, there is provided a piezoelectric portion formed by two-dimensionally arranging a plurality of piezoelectric elements that mutually convert an electric signal and an ultrasonic signal by utilizing a piezoelectric phenomenon, and an ultrasonic absorber. A method of manufacturing an ultrasonic probe comprising: an acoustic braking member configured to absorb an ultrasonic wave radiated from the piezoelectric portion; and an electrode surface on each of the acoustic braking member and each piezoelectric element. the while forming respectively, a first step of forming an electrode surface having a plurality of fine convex portions of one of the electrode surface and the electrode surface of the piezoelectric element of the acoustic damping member, the acoustic damping member side The acoustic braking member and each piezoelectric element are arranged in such a manner that the electrode surface and the electrode surface on the piezoelectric element side face each other, and the minute convex portion is compressed by the electrode surface on the opposite side and partially collapsed. 2nd which joins each said electrode surface And a step.

  According to the present invention, an electrode surface is formed on each of the acoustic braking member and each piezoelectric element, and at least one of the electrode surface of the acoustic braking member and the electrode surface of the piezoelectric element is provided with a plurality of minute convex portions. Since the acoustic braking member and each piezoelectric element are joined together between the electrode surfaces, even if there is a variation in the gap between each piezoelectric element and the acoustic braking member, An electrical connection between the electrode surface of each piezoelectric element and the electrode surface of the acoustic braking member can be reliably ensured.

According to a second aspect of the invention, the ultrasonic probe method according to claim 1, wherein the first step, with a plurality of the convex portions using a conductive resin to the acoustic damping member forming an electrode surface, including the step of forming the electrode surface to the piezoelectric element by silver baking method.

  According to the present invention, the acoustic braking member and the acoustic braking member may be pierced into an electrode surface formed on the piezoelectric element by a silver baking method with a plurality of protrusions formed using conductive resin on the acoustic braking member. Since each of the piezoelectric elements is joined to the electrode surfaces, even if there is a variation in the gap between each piezoelectric element and the acoustic braking member, the electrode surface of each piezoelectric element and the electrode surface of the acoustic braking member It is possible to ensure the electrical connection.

According to a third aspect of the present invention, in the method of manufacturing an ultrasonic probe according to the first or second aspect, an electrode surface including a plurality of the convex portions is formed using a conductive resin for the acoustic braking member. The process includes forming a through hole in the acoustic braking member corresponding to the arrangement of the piezoelectric elements, filling the through hole with the conductive resin, and forming the through hole in the through hole. Forming a plate-shaped electrode base using conductive resin at the end of each filler, and forming the plurality of convex portions using conductive resin on the electrode base by a screen printing method. Forming an electrode surface having a plurality of portions.

  According to this invention, the electrode surface provided with a plurality of minute protrusions can be formed on the acoustic braking member.

According to a fourth aspect of the present invention, in the method of manufacturing an ultrasonic probe according to any one of the first to third aspects, the first step includes a roughening process on the surface of the piezoelectric element. Forming a plurality of convex portions, forming a metal film on the surface subjected to the roughening treatment to form an electrode surface having a plurality of convex portions, and applying the acoustic braking member to the acoustic braking member. including the step of forming the electrode surface using a conductive resin or metallic material.

  According to this invention, in a mode in which each convex portion is compressed by pressing a plurality of convex portions formed on the piezoelectric element against an electrode surface formed using a conductive resin or metal material on the acoustic braking member. Since the acoustic braking member and the piezoelectric elements are bonded to each other at the electrode surfaces, even if there is a variation in the gap between the piezoelectric elements and the acoustic braking member, the acoustic braking member and the piezoelectric elements are acoustically connected to each other. Electrical connection with the electrode surface of the braking member can be ensured reliably.

According to a fifth aspect of the present invention, there is provided a piezoelectric portion in which a plurality of piezoelectric elements that mutually convert an electric signal and an ultrasonic signal by utilizing a piezoelectric phenomenon are two-dimensionally arranged, and an ultrasonic absorber. It is constructed using the an ultrasound probe and an acoustic damping member that absorbs the ultrasonic waves emitted are stacked from the piezoelectric unit, produced by the method according to any one of claims 1 to 4 It has been done.

According to a sixth aspect of the present invention, there is provided a piezoelectric portion in which a plurality of piezoelectric elements that mutually convert an electric signal and an ultrasonic signal by utilizing a piezoelectric phenomenon are two-dimensionally arranged, and an ultrasonic absorber. An ultrasonic probe formed by stacking an acoustic braking member that absorbs ultrasonic waves radiated from the piezoelectric unit, the electrode surface formed on the acoustic braking member, and each piezoelectric element An electrode surface formed on the element, and a plurality of minute convex portions formed on one of the electrode surface of the acoustic braking member and the electrode surface of the piezoelectric element , The acoustic braking member and the piezoelectric elements are joined to each other on the electrode surfaces in such a manner that the acoustic braking member and the piezoelectric elements are crushed partially .

  According to these inventions, it is possible to realize an ultrasonic probe in which electrical connection between each piezoelectric element two-dimensionally arranged in the piezoelectric portion and the acoustic braking member is ensured.

The invention according to claim 7, the ultrasonic probe according to claim 6 which outputs an ultrasonic signal to a subject, converts the ultrasound signal reflected by the analyte into an electric signal And an image processing unit that receives an electrical signal output from the ultrasound probe and generates an image of an internal state of the subject based on the electrical signal.

  According to the present invention, it is possible to realize an ultrasonic diagnostic apparatus having an ultrasonic probe in which electrical connection between each piezoelectric element provided in the piezoelectric portion and the acoustic braking member is reliably ensured.

  According to the present invention, it is possible to reliably ensure electrical connection between each piezoelectric element and the acoustic braking member.

It is a figure which shows an example of the external appearance structure of the ultrasonic diagnosing device which concerns on this invention. It is a block diagram which shows the electrical structure of an ultrasonic diagnosing device. It is a figure which shows the structure of the ultrasound probe in an ultrasound diagnosing device. It is a figure for demonstrating 1st Embodiment which concerns on the joining process of an acoustic braking member and a piezoelectric part. It is an enlarged view which shows the structure of an electrode base and a convex part. A gap Δd1 between a certain piezoelectric element and the acoustic braking member and a gap Δd2 between another piezoelectric element and the acoustic braking member (Δd1 <Δ) when the planned joining surface of the acoustic braking member and the planned joining surface of the piezoelectric portion are joined. It is a figure showing the case where (DELTA) d2) differs. It is a figure for demonstrating 2nd Embodiment which concerns on the joining process of an acoustic braking member and a piezoelectric part. A gap Δd11 between a certain piezoelectric element and the acoustic braking member and a gap Δd12 between another piezoelectric element and the acoustic braking member (Δd11 <Δ) when the planned joining surface of the acoustic braking member and the scheduled joining surface of the piezoelectric portion are joined. It is a figure showing the case where (DELTA) d12) differs.

  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.

  FIG. 1 is a diagram showing an external configuration of an ultrasonic diagnostic apparatus. FIG. 2 is a block diagram showing an electrical configuration of the ultrasonic diagnostic apparatus. FIG. 3 is a diagram illustrating a configuration of an ultrasound probe in the ultrasound diagnostic apparatus.

  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 a command for instructing diagnosis, personal information data of the subject, and the like, and is, for example, an operation panel or a keyboard provided with a plurality of input switches.

  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, the receiver 13 amplifies the received signal with a predetermined amplification factor set in advance to compensate for transmission loss (transmission loss) of the cable 3, and the received signal amplified by the amplifier is an analog signal. An analog-digital converter for converting from a digital signal to a digital signal is provided.

  The image processing unit 14 is a circuit that generates an image (ultrasonic image) representing the internal state in the subject based on the received signal received by the receiving unit 13 under the control of the control unit 16.

  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 it may be configured to generate an ultrasound image, from the viewpoint of obtaining a more accurate ultrasound image, the image processing unit 14 is based on the received signal received by the receiving unit 13 by the above-described harmonic imaging technique. And an ultrasonic image of the subject may be generated.

  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 harmonics, for example, is in phase, so that the first and second received signals are added together to add the first and second received signals. Second harmonic components are 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 FIG. 3 (A), the ultrasonic probe 2 is laminated on a plate-like acoustic braking member 21 (21A, 21B, 21C) and one main surface of the acoustic braking member 21. The piezoelectric unit 22 includes an acoustic matching layer 23 stacked on the piezoelectric unit 22 and an acoustic lens 24 stacked on the acoustic matching layer 23.

  The acoustic braking member 21 is made of a material that absorbs ultrasonic waves (ultrasonic absorbing material), and mainly absorbs ultrasonic waves radiated from the piezoelectric portion 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 piezoelectric portion 22 good by sufficiently attenuating the ultrasonic wave.

  The acoustic braking member 21 mechanically supports the piezoelectric unit 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 scatterer.

  The acoustic scattering powder includes 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. In the acoustic braking member 21, a plurality of columnar conductive portions 102 (see FIG. 4), which are electrical conductors, are embedded in the ultrasonic absorber. The acoustic braking member 21 will be described in detail later.

  The piezoelectric portion 22 includes a plurality of piezoelectric elements that are electrically connected to the plurality of columnar conductive portions 102 in the acoustic braking member 21 and convert electrical signals and ultrasonic signals to each other by using a piezoelectric phenomenon. Composed.

  The piezoelectric unit 22 is configured by two-dimensionally arranging the plurality of piezoelectric elements in an array of m rows × n columns in two linearly independent directions in a plan view with a predetermined interval therebetween. m and n are positive integers, for example, m = n = 128. In this case, the number of piezoelectric elements is 128 × 128 = 16384, and the number of columnar conductive portions 102 of the acoustic braking member 21 is 16384 accordingly. The gap generated by the predetermined interval is preferably filled with an ultrasonic absorber from the viewpoint of reducing crosstalk between the plurality of piezoelectric elements.

  Each piezoelectric element includes an electrode on each of both opposing surfaces of a piezoelectric body made of a piezoelectric material. One of the electrodes in each piezoelectric element is grounded, and the other electrode is electrically connected to the columnar conductive portion 102 of the acoustic braking member 21. The thickness of the piezoelectric body is appropriately set depending on, for example, the frequency of ultrasonic waves to be transmitted and received, the type of piezoelectric material, and the like.

  To each of the plurality of piezoelectric elements, a transmission signal of an electrical signal input from the transmitter 12 via the cable 3 to the ultrasonic probe 2 is input via each of the plurality of columnar conductive portions 102. The Each piezoelectric element converts this electric signal into an ultrasonic signal by utilizing a piezoelectric phenomenon and transmits the ultrasonic signal.

  Then, when the ultrasonic probe 2 is applied to the subject, an ultrasonic signal generated by each piezoelectric element of the piezoelectric unit 22 is transmitted into the subject as a first ultrasonic signal. On the other hand, each piezoelectric element of the piezoelectric unit 22 receives a second ultrasonic signal coming from within the subject based on the first ultrasonic signal, and the received second ultrasonic signal is electrically generated by utilizing a piezoelectric phenomenon. It converts into a signal and outputs the electrical signal. This electrical signal is output from the electrodes of each piezoelectric element via each of the plurality of columnar conductive portions 102. 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.

  Here, as shown in FIG. 3B, the piezoelectric portion 22 includes a transmission piezoelectric portion 221 laminated on one main surface of the acoustic braking member 21 and an intermediate layer laminated on the transmission piezoelectric portion 221. The layer 222 and the receiving piezoelectric portion 223 stacked on the intermediate layer 222 may be provided.

  The transmission piezoelectric unit 221 includes an inorganic piezoelectric material, and converts a transmission electrical signal into a first ultrasonic signal by utilizing a piezoelectric phenomenon. Inorganic piezoelectric materials include, for example, so-called PZT, quartz, lithium niobate (LiNbO3), potassium niobate tantalate (K (Ta, Nb) O3), barium titanate (BaTiO3), lithium tantalate (LiTaO3) and titanate. Strontium (SrTiO3) or the like.

  The intermediate layer (buffer layer) 222 is a member for laminating the transmission piezoelectric unit 221 and the reception piezoelectric unit 223. In the present embodiment, the intermediate layer 222 is a member that matches the acoustic impedances of the transmission piezoelectric unit 221 and the reception piezoelectric unit 223.

  The receiving piezoelectric unit 223 includes an organic piezoelectric material, and converts the second ultrasonic signal coming from within the subject based on the first ultrasonic signal into a received electric signal by using a piezoelectric phenomenon. is there. As the organic piezoelectric material, for example, a polymer of vinylidene fluoride or a vinylidene fluoride (VDF) copolymer can be used. The vinylidene fluoride copolymer is a copolymer (copolymer) of vinylidene fluoride and other monomers. Examples of the other monomers include ethylene trifluoride, tetrafluoroethylene, perfluoroalkyl vinyl ether (PFA). ), Perfluoroalkoxyethylene (PAE), perfluorohexaethylene, and the like. In the vinylidene fluoride copolymer, the electromechanical coupling constant (piezoelectric effect) in the thickness direction varies depending on the copolymerization ratio. For example, an appropriate copolymerization ratio is adopted according to the specifications of the ultrasonic probe 2 and the like. The

  In such a configuration, the piezoelectric unit 22 is functionally separated into the transmitting piezoelectric unit 221 and the receiving piezoelectric unit 223, and the transmitting piezoelectric unit 221 is configured to include an inorganic piezoelectric material. Therefore, it is possible to increase the transmission power with a relatively simple structure. For this reason, the ultrasonic probe 2 including the piezoelectric unit 22 can transmit the first ultrasonic signal of the fundamental wave with a relatively large power, and obtain a higher harmonic component of the second ultrasonic signal. be able to.

  The receiving piezoelectric portion 223 is configured to include an organic piezoelectric material. Therefore, since the ultrasonic probe 2 including the piezoelectric portion 22 can make the frequency band wide with a relatively simple structure, it can receive the harmonic component included in the second ultrasonic signal. Is possible. For this reason, this ultrasonic probe 2 can receive suitably the high frequency component of a 2nd ultrasonic signal. In particular, since the ultrasonic probe 2 including the piezoelectric unit 22 having such a configuration can suitably receive the harmonic component of the second ultrasonic signal, an ultrasonic image is formed by the harmonic imaging technique described above. This is suitable for the ultrasonic diagnostic apparatus S.

  Further, as shown in FIG. 3B, since the transmitting piezoelectric portion 221 and the receiving piezoelectric portion 223 are laminated, the piezoelectric portion 22 and the ultrasonic probe 2 can be reduced in size. . Further, as shown in FIG. 3B, a receiving piezoelectric portion 223 is disposed between the transmitting and receiving surfaces of the first and second ultrasonic signals (the surface of the acoustic lens 24) and the transmitting piezoelectric portion 221. Therefore, it is possible to reduce the reception noise and improve the SN ratio.

  Returning to FIG. 3A, the acoustic matching layer 23 is a member that matches the acoustic impedance of the piezoelectric portion 22 and the acoustic impedance of the subject. The acoustic matching layer 23 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 23 is preferably composed of a plurality of layers. The acoustic lens 24 is a member that converges the ultrasonic wave transmitted toward the subject, and has, for example, a shape that bulges in an arc as shown in FIG. Note that the acoustic matching layer 23 and the acoustic lens 24 may be integrally formed.

  In the ultrasonic diagnostic apparatus S having such a configuration, 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. In the piezoelectric unit 22, when the electrical signal transmission signal is supplied, each of the plurality of piezoelectric elements expands and contracts in the thickness direction, and ultrasonically vibrates in accordance with the electrical signal transmission signal. Due to this ultrasonic vibration, the piezoelectric unit 22 radiates an ultrasonic wave (first ultrasonic signal) through the acoustic matching layer 23 and the acoustic lens 24. 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.

  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. More specifically, the second ultrasonic signal is received by the piezoelectric unit 22 via the acoustic lens 24 and the acoustic matching layer 23, and mechanical vibration is converted into an electric signal by the piezoelectric unit 22 as a received signal. It is taken out. 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 reception processing on the input reception signal, more specifically, for example, after amplification, converts the analog signal into a digital signal and outputs the converted signal to the image processing unit 14.

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

  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.

  By the way, in this case, in the joining process of the acoustic braking member 21 and the piezoelectric part 22 performed in the manufacturing process of the ultrasonic probe 2, the following method is employed, which is different from the conventional technique. . Hereinafter, this point will be described. FIG. 4 is a view for explaining the first embodiment relating to the joining process of the acoustic braking member 21 and the piezoelectric portion 22.

(First embodiment)
As shown in FIG. 4 (a), first, a planned joining surface 104 (upper surface in FIG. 4 (a)) of a base material 100 (hereinafter referred to as a backing material 100) that is a material of the acoustic braking member 21 will be described later. The through holes 101 are formed in a form (matrix shape) corresponding to the arrangement state of the piezoelectric elements 115 generated in another process, and as shown in FIG. 4B, each through hole 101 is filled with a conductive paste. The columnar conductive portions 102 are respectively formed.

  In addition, the thickness of the backing material 100 is preferably in the range of 1.5 to 2.5 mm, and the diameter of each through hole 101 is preferably in the range of 100 to 150 μm. Further, the conductive paste filled in the through hole 101 is preferably a conductive paste that does not contain a solvent and has a relatively small dispersed metal (for example, AE1650 manufactured by Tatsuta System Electronics Co., Ltd.). Any metal can be used as long as the metal is dispersed and mixed.

  Next, as shown in FIG. 4C, a plate-like electrode base 103 in which copper or a surface of copper is coated with gold is formed at the end of the columnar conductive portion 102 by electroless plating and / or electrolytic plating. To do. At this time, the electrode base 103 made of metal is arranged on the planned joining surface 104 of the backing material 100 in a manner corresponding to the arrangement state of the piezoelectric elements. In addition, the electrode base 103 formed on the lower surface 105 side shown in FIG. 4C is an electrode connected to a substrate (not shown).

  Further, as shown in FIG. 4D, a minute convex portion 106 is formed on the electrode base portion 103 formed on the planned joining surface 104 by a screen printing technique. As a result, an electrode surface having minute convex portions 106 is formed on the planned joining surface 104 of the acoustic braking member 21. Note that a mask used in the screen printing process is manufactured in advance using a photomask. Note that the minute protrusion 106 does not need to be formed only on the electrode base 103, and even if it is formed on the entire surface to be bonded 104, there is no particular problem in terms of performance.

  FIG. 5 is an enlarged view showing the configuration of the electrode base 103 and the convex portion 106. As shown in FIG. 5, the convex portion 106 is formed in a conical shape having a bottom surface diameter R of, for example, 10 μm and a height H of, for example, 15 μm. However, the diameter R and the height H of the bottom surface may be appropriately set according to the number, density, and the like of the electrode bases 103 within a preferable setting range of 2 to 200 μm.

  On the other hand, on the piezoelectric portion 22 side, as shown in FIG. 4E, silver baking is performed on the upper and lower surfaces 111 and 112 of the piezoelectric base material 110, which is a material of the piezoelectric portion 22, as shown in FIG. Electrode layers 113 and 114 are formed by a construction method. In the silver baking method, metallic silver (Ag) powder mixed with a small amount of lead borosilicate glass frit is dissolved in a paste with an organic solvent, which is applied to the ceramic surface with a brush or screen. It is performed by heating to ˜800 (° C.) to decompose the organic matter, melting the glass frit, and bringing the silver particles into close contact with the ceramic surface.

  Next, as shown in FIG. 4G, the piezoelectric substrate 110 on which the electrode layers 113 and 114 are formed is cut into a lattice shape (matrix shape) when viewed from the lower surface 112 side. As a result, the plurality of piezoelectric elements 115 are formed in a form having a certain gap 116 between the adjacent piezoelectric elements 115.

  Then, as shown in FIG. 4H, the gap 116 is filled with a filler made of an insulating material such as a polymer material to form a partition wall 117. In addition, in FIG.4 (g), the lower surface 112 is a joining plan surface with the acoustic braking member 21. FIG.

  When the acoustic braking member 21 and the piezoelectric portion 22 are manufactured as described above, at least one of the planned joining surface 104 of the acoustic braking member 21 and the planned joining surface 112 of the piezoelectric portion 22 (here, the piezoelectric portion). 22 only), after applying an adhesive such as an epoxy-based adhesive, as shown in FIG. 4 (i), the bonding planned surface 104 of the acoustic braking member 21 and the piezoelectric part 22 are scheduled to be bonded. The acoustic braking member 21 and the piezoelectric portion 22 are pressure-bonded with the surface 112 facing each other.

  At this time, the convex portion 106 of the acoustic braking member 21 formed of the conductive paste has a higher hardness than the electrode layer 114 formed on the piezoelectric portion 22, and thus pierces the electrode layer 114 (one aspect of the deformation). . As a result, the acoustic braking member 21 and the piezoelectric portion 22 are electrically connected.

  As described above, according to the present embodiment, the electrode surface having the minute convex portion 106 is formed on the bonding planned surface 104 of the acoustic braking member 21, and the bonding planned surface 104 of the acoustic braking member 21 and the piezoelectric portion 22 are formed. Since each of the piezoelectric elements 115 can be reliably electrically connected to (coupled to) the acoustic braking member 21.

  That is, as shown in FIG. 6, the gap Δd1 between a certain piezoelectric element 115 and the acoustic braking member 21 when the planned joining surface 104 of the acoustic braking member 21 and the scheduled joining surface 112 of the piezoelectric portion 22 are joined, It is assumed that the gap Δd2 (Δd1 <Δd2 in FIG. 6) between another piezoelectric element 115 and the acoustic braking member 21 is different.

  At this time, if the convex portion 106 is not formed as in the present embodiment, the piezoelectric element 115 (the left piezoelectric element 115 in FIG. 6) whose gap with the acoustic braking member 21 is Δd1 is connected to the piezoelectric portion 22. Even if the applied adhesive layer 107 adheres to the acoustic braking member 21 and can be electrically connected to the acoustic braking member 21 via the adhesive layer 107, the gap with the acoustic braking member 21 is not reduced. For the piezoelectric element 115 (right side piezoelectric element 115 in FIG. 6) having Δd2, the adhesive layer 107 does not adhere (not reach) the acoustic braking member 21 and is electrically connected to the acoustic braking member 21. May not be possible.

  On the other hand, in the present embodiment, an electrode having the convex portion 106 is formed on the planned joining surface 104 of the acoustic braking member 21, and the convex portion 106 becomes a piezoelectric portion when the acoustic braking member 21 and the piezoelectric portion 22 are joined. Since the piezoelectric element 115 has a relatively large gap with the acoustic braking member 21, it can be electrically connected to the acoustic braking member 21 through the convex portion 106.

  That is, the gap 106 between the acoustic braking member 21 and the piezoelectric element 115 is absorbed by the convex portion 106. Thereby, even if the gap between the piezoelectric portion 22 and the acoustic braking member 21 is varied, each piezoelectric element 115 can be reliably electrically connected to the acoustic braking member 21.

(Second Embodiment)
Next, a second embodiment relating to the joining process of the acoustic braking member 21 and the piezoelectric portion 22 will be described. FIG. 7 is a view for explaining a second embodiment relating to a joining process of the acoustic braking member 21 and the piezoelectric portion 22.

  About manufacture of the electrode in the acoustic braking member 21, as shown to Fig.7 (a)-(c), the process similar to Fig.4 (a)-(c) is performed. That is, as shown in FIG. 7A, first, with respect to a planned joining surface 204 (upper surface in FIG. 7A) of a base material 200 (hereinafter referred to as a backing material 200) that is a material of the acoustic braking member 21, Through holes 201 are formed in a form (matrix shape) corresponding to the arrangement state of piezoelectric elements 215 generated in another process, which will be described later, and a conductive paste is applied to each through hole 201 as shown in FIG. The columnar conductive portions 202 are respectively formed by filling.

  Next, as shown in FIG. 7C, a flat counter electrode 203 is formed on the end of the columnar conductive portion 202 using the conductive paste by a printing technique such as screen printing. In the present embodiment, the processing on the backing material 200 is up to here, and the process of forming the convex portion 106 as in the first embodiment on the acoustic braking member 21 (the process shown in FIG. 4D). Not implemented.

  On the other hand, regarding the manufacture of the electrodes in the piezoelectric portion 22, as shown in FIG. 7D, the bonding surface (the lower surface in FIG. 7D) 211 of the piezoelectric substrate 210 that is the material of the piezoelectric portion 22 is compared. As shown in FIG. 7E, a roughening process is performed to form a plurality of convex portions 212 arranged two-dimensionally on the planned joining surface 211. As the roughening treatment, for example, an appropriate polishing paper or polishing puff may be used with an automatic polishing apparatus. It is also possible to employ a blasting method in which the surface is roughened by striking a small granular abrasive or similar material on the surface of the object.

  Next, as shown in FIG. 7F, an electrode film 213 made of gold is formed by sputtering on the planned joining surface 211 on which the projections 212 are formed. In the state where the electrode film 213 is formed, it is desirable that the surface roughening treatment is performed so that the surface roughness Rmax of the surface to be bonded of the piezoelectric substrate 210 is 2 to 10 μm. Then, as shown in FIGS. 7 (g) and 7 (h), the same cutting process and filling material filling process as in FIGS. 4 (f) and 4 (g) are performed. As a result, an electrode surface having minute convex portions 212 is formed.

  When the acoustic braking member 21 and the piezoelectric portion 22 are manufactured as described above, at least one of the planned joining surface 204 of the acoustic braking member 21 and the scheduled joining surface 211 of the piezoelectric portion 22 (here, piezoelectric). After applying an adhesive such as an epoxy-based adhesive, for example, as shown in FIG. 4 (i), the bonding planned surface 204 of the acoustic braking member 21 and the piezoelectric unit 22 are bonded. The acoustic braking member 21 and the piezoelectric portion 22 are pressure-bonded with the planned surface 211 facing each other.

  At this time, the convex portion 212 of the piezoelectric portion 22 has a lower hardness than the counter electrode 203 formed on the acoustic braking member 21. Therefore, when the acoustic braking member 21 and the piezoelectric portion 22 are joined to each other at the joining planned surfaces 204 and 211 and pressed together, the convex portion 212 is compressed and partially collapsed (one aspect of the deformation). As a result, the acoustic braking member 21 and the piezoelectric portion 22 are electrically connected.

  As described above, according to the present embodiment, the electrode surface having the minute convex portions 212 is formed on the planned bonding surface 211 of the piezoelectric portion 22, and the acoustic braking member 21 and the piezoelectric portion 22 are bonded to the planned bonding surface 204. Since the two members 211 are joined together, electrical conduction between the acoustic braking member 21 and the piezoelectric portion 22 can be reliably ensured.

  That is, as shown in FIG. 8, a gap Δd11 between a certain piezoelectric element 215 and the acoustic braking member 21 when the planned joining surface 204 of the acoustic braking member 21 and the scheduled joining surface 211 of the piezoelectric portion 22 are joined, It is assumed that the gap Δd12 (Δd11 <Δd12 in FIG. 8) between the other piezoelectric element 215 and the acoustic braking member 21 is different.

  At this time, if the convex portion 212 is not formed as in the present embodiment, the piezoelectric element 215 (the left piezoelectric element 215 in FIG. 8) whose gap with the acoustic braking member 21 is Δd11 is formed in the piezoelectric portion 22. Even if the applied adhesive layer 207 adheres to the acoustic braking member 21 and can be electrically connected to the acoustic braking member 21 via the adhesive layer 207, the gap with the acoustic braking member 21 is not reduced. For the piezoelectric element 215 having a value Δd12 (the right side piezoelectric element 215 in FIG. 8), the adhesive layer applied to the piezoelectric portion 22 does not adhere (not reach) the acoustic braking member 21, and the electrical braking member 21 is electrically connected to the acoustic braking member 21. May not be able to conduct.

  On the other hand, in this embodiment, an electrode surface having the convex portion 212 is formed on the planned joining surface 211 of the piezoelectric portion 22, and the convex portion 212 is compressed when the acoustic braking member 21 and the piezoelectric portion 22 are joined. Since the structure is crushed, the piezoelectric element 215 having a relatively large gap with the acoustic braking member 21 can be electrically connected to the acoustic braking member 21 via the convex portion 212.

  That is, the convex portion 212 absorbs the variation in the gap between the acoustic braking member 21 and the piezoelectric element 215. Thereby, even if the gap between the piezoelectric portion 22 and the acoustic braking member 21 is varied, each piezoelectric element 215 can be reliably electrically connected to the acoustic braking member 21.

  In this case, the following modifications may be employed instead of or in addition to the above embodiments.

  [1] In the second embodiment, when the acoustic braking member 21 and the piezoelectric part 22 are joined together by the respective joining planned surfaces 204 and 211, a part of the convex part 212 formed on the piezoelectric part 22 side. However, the material of the convex part 212 and the shape of the convex electrode 212 or the material of the counter electrode 203 formed on the acoustic braking member 21 are appropriately changed and adjusted, so that the convex part 212 is formed into the counter electrode 203. You may make it pierce.

  In this case, instead of the step shown in FIG. 7F of the second embodiment, that is, the step of forming the electrode film 213 made of gold by sputtering, the roughening of the piezoelectric substrate 210 is performed. For example, a process of forming an electrode film made of a conductive paste on the planned bonding surface 211 that has been processed and forming the convex portion 212 on the piezoelectric portion 22 can be employed.

  The conductive paste used at this time may be the same as the conductive paste used to form the columnar conductive portion 202 used in the step shown in FIG. In order to make the counter electrode 203 easily stick, the hardness of the conductive paste for forming the counter electrode 203 is relatively smaller than the hardness of the conductive paste for forming the convex portion 212. It is good to do so. The film thickness of the electrode film of the conductive paste formed on the planned bonding surface 211 of the piezoelectric portion 22 is preferably in the range of 2 to 20 μm, and is set to 7 μm here.

  Also in the present embodiment, as in the first and second embodiments, there is an effect that electrical conduction between the acoustic braking member 21 and each piezoelectric element 215 of the piezoelectric portion 22 can be reliably ensured. .

  [2] In the first embodiment, the convex portion 106 formed on the acoustic braking member 21 pierces the electrode layer 114 formed on the piezoelectric portion 22, and the acoustic braking member 21 and each piezoelectric element 115 are Although electrical continuity is achieved, a part of the convex portion 106 is compressed and crushed by changing / adjusting the material and shape of the convex portion 106 or the material of the electrode layer 114 formed on the piezoelectric portion 22. You may do it.

  In this case, considering the ease of crushing of the convex portion 106, a sharper shape (conical shape having a relatively large height H with respect to the diameter R) is preferable, but the conical shape formed by the convex portion 106 is preferable. If the volume is too large (the volume is too large), the adhesive layer formed between the acoustic braking member 21 and the piezoelectric portion 22 becomes thick, which is not preferable in terms of ultrasonic characteristics.

  In order to make the conical shape formed by the convex portion 106 sharper, for example, the size of the opening of the screen, the viscoelasticity of the conductive paste, the speed, material (hardness) or pressing force of the squeegee are appropriately set. It can be realized by setting.

  Also in the present embodiment, as in the first and second embodiments, an effect is obtained that electrical continuity between the acoustic braking member 21 and each piezoelectric element 115 of the piezoelectric portion 22 can be reliably ensured. .

DESCRIPTION OF SYMBOLS S Ultrasonic diagnostic apparatus 1 Ultrasonic diagnostic apparatus main body 2 Ultrasonic probe 16 Control part 21 Acoustic damping member 22 Piezoelectric part 100,200 Backing material 101,201 Through-hole 102,202 Columnar conductive part 103 Electrode base 104,112, 204, 211 Planned bonding surface 107 Adhesive layer 203 Counter electrode 106, 212 Protruding portion 110, 210 Piezoelectric base material 113, 114 Electrode layer 115, 215 Piezoelectric element 116 Gap 117 Partition wall 213 Electrode film

Claims (7)

A piezoelectric part formed by two-dimensionally arranging a plurality of piezoelectric elements that mutually convert an electrical signal and an ultrasonic signal by using a piezoelectric phenomenon, and an ultrasonic absorber, A method of manufacturing an ultrasonic probe in which an acoustic braking member that absorbs emitted ultrasonic waves is laminated,
The electrode surface and forming respectively the acoustic damping member and the respective piezoelectric elements, formed as the electrode surface and one electrode surface having a plurality of fine convex portion of the electrode surfaces of the piezoelectric elements of the acoustic damping member A first step;
The acoustic braking member side electrode surface and the piezoelectric element side electrode surface are opposed to each other, and the minute convex portion is compressed by the opposing electrode surface and partially collapsed , A method of manufacturing an ultrasonic probe, comprising: a second step of joining each of the piezoelectric elements at the electrode surfaces. The first step includes
Forming an electrode surface having a plurality of the convex portions using a conductive resin for the acoustic braking member;
Forming the electrode surface on the piezoelectric element by a silver baking method;
The method of manufacturing an ultrasonic probe according to claim 1. The step of forming an electrode surface comprising a plurality of the convex portions using a conductive resin for the acoustic braking member,
Forming a through-hole in the acoustic braking member corresponding to the arrangement of the piezoelectric elements,
Filling each through hole with the conductive resin;
Forming a plate-like electrode base using a conductive resin at the end of each filler formed in each through hole; and
Forming an electrode surface having a plurality of protrusions by forming a plurality of protrusions using a conductive resin on the electrode base by a screen printing method; and
The manufacturing method of the ultrasonic probe of Claim 1 or 2 containing this . The first step includes
A step of roughening the surface of the piezoelectric element to form a plurality of convex portions;
Forming an electrode surface having a plurality of the convex portions by forming a metal film on the surface subjected to the roughening treatment;
Forming the electrode surface using a conductive resin or metal material for the acoustic braking member;
The method for manufacturing an ultrasonic probe according to any one of claims 1 to 3 . A piezoelectric part formed by two-dimensionally arranging a plurality of piezoelectric elements that mutually convert an electrical signal and an ultrasonic signal by using a piezoelectric phenomenon, and an ultrasonic absorber, An ultrasonic probe in which an acoustic braking member that absorbs emitted ultrasonic waves is laminated,
  An ultrasonic probe manufactured by the manufacturing method according to claim 1. A piezoelectric part formed by two-dimensionally arranging a plurality of piezoelectric elements that mutually convert an electrical signal and an ultrasonic signal by using a piezoelectric phenomenon, and an ultrasonic absorber, An ultrasonic probe in which an acoustic braking member that absorbs emitted ultrasonic waves is laminated,
An electrode surface formed on the acoustic braking member;
An electrode surface formed on each of the piezoelectric elements,
In a mode in which a plurality of minute convex portions formed on one of the electrode surfaces of the acoustic braking member and the electrode surface of the piezoelectric element are compressed by a facing electrode surface and partially collapsed, An ultrasonic probe in which an acoustic braking member and each of the piezoelectric elements are joined to each other on the electrode surfaces . The ultrasonic probe according to claim 6, which outputs an ultrasonic signal to a subject, converts the ultrasonic signal reflected by the subject into an electrical signal, and outputs the electrical signal;
An image processing unit that receives an electrical signal output from the ultrasound probe and generates an image of an internal state of the subject based on the electrical signal;
An ultrasonic diagnostic apparatus comprising:

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