JP5905192B2 - Manufacturing method of ultrasonic probe - Google Patents

Description

The present invention relates to an ultrasonic probe manufacturing method .

  In an ultrasonic diagnostic apparatus that irradiates a subject with ultrasonic waves and images reflected echoes thereof, an ultrasonic probe that transmits and receives ultrasonic waves is connected to the main body of the ultrasonic diagnostic apparatus. In general, an ultrasonic probe is disposed on a piezoelectric layer, an acoustic matching layer disposed on the ultrasonic irradiation side with respect to the piezoelectric body, and on an opposite side to the ultrasonic irradiation side with respect to the piezoelectric layer. A backing material layer and a flexible printed circuit board sandwiched between the backing material and the piezoelectric body and connected to the electrodes of the piezoelectric body are provided.

  As a piezoelectric material, a piezoelectric ceramic such as PZT (lead zirconate titanate) has been used as a material having a large electromechanical coupling coefficient and a large dielectric constant that can be easily matched with a transmission circuit. On the other hand, in recent years, a magnesium niobate / lead titanate solid solution (PMN-PT) piezoelectric single crystal having a higher electromechanical coupling coefficient than conventional PZT has been developed and used as a piezoelectric body. Accordingly, a technique for expecting high sensitivity of an ultrasonic probe is disclosed (see Patent Document 1).

  Conventionally, as a piezoelectric body of an ultrasonic probe, electrodes are formed on both surfaces of a piezoelectric body of a single crystal or a uniaxially oriented crystal. However, since the single crystal material has a low fracture toughness and is brittle, there is a problem that a cutting defect such as chipping is likely to occur when forming an array by dicing or the like (see Patent Document 2). .

  As shown in FIG. 1, the cross-sectional structure of an ultrasonic probe using a conventional single crystal piezoelectric body has electrodes 5 and 6 formed on both sides of the single crystal piezoelectric body 1. An acoustic matching layer 2 is formed on the upper surface, and the single crystal piezoelectric body 1 and the acoustic matching layer are processed into an array. The element pitch for array processing is about 0.1 mm to 0.3 mm.

  A plurality of acoustic matching layers 2 may be provided in order to efficiently propagate ultrasonic waves. On the upper surface of the acoustic matching layer 2, an acoustic lens 3 that efficiently enters ultrasonic waves into a subject is provided, and ultrasonic waves are transmitted and received through the acoustic lens 3. A backing layer 4 is provided on the lower surface of the single crystal piezoelectric body 1. Electrodes 5 for taking out ground (GND) and electrodes 6 for taking out signals are formed on both surfaces of the single crystal piezoelectric body 1 and are connected to a cable via a flexible printed circuit board (FPC) 7 for diagnosis. Connected to the device body (not shown).

  In the structure of FIG. 1, a flexible printed circuit board (FPC) 7 is bonded to the piezoelectric element over the entire surface with an epoxy adhesive or the like by expanding the conductive layer of the FPC to the area of the piezoelectric element. Further, as the conductive layer, metal copper (Cu) is generally used.

  The array structure is fabricated as described below.

  Electrodes 5 and 6 are formed on the single crystal piezoelectric body 1 having an integral shape. In order, after attaching the flexible printed circuit board (FPC) 7 and the single crystal piezoelectric body 1 to the backing layer 4 and attaching the acoustic matching layer 2, the substrate is cut from the matching layer side using a dicing saw. Thereafter, the acoustic lens 3 is formed on the acoustic matching layer 2 to complete.

  By the way, in the ultrasonic probe manufactured by the above manufacturing method, the single crystal piezoelectric body having low mechanical strength is likely to be chipped and cracked by dicing. When the electrode is formed on the single crystal itself, the electrode is formed by chipping. There is a risk of peeling and continuity. In addition, since the electrode area of the piezoelectric element processed into an array is also reduced, it becomes a factor causing characteristic deterioration.

Japanese Unexamined Patent Publication No. 7-50898 JP 2002-34098 A

The present invention has been made in view of the above problems, and its solution is to conduct electricity by peeling the electrodes even when single-crystal piezoelectric elements cause chipping during array-shaped cutting (dicing). It is an object of the present invention to provide a method of manufacturing an ultrasonic probe that can ensure reliable conduction without causing a defect and that has a high manufacturing process yield .

  The above-mentioned problem according to the present invention is solved by the following means.

1. A method of manufacturing an ultrasonic probe in which a piezoelectric body that is a single crystal or a uniaxially oriented crystal and an acoustic matching layer are laminated via electrodes, the deposition method or the sputtering method only on the surface of the acoustic matching layer. A method of manufacturing an ultrasonic probe, comprising: forming an electrode; and bonding the acoustic matching layer on which the electrode is formed and the piezoelectric body via the electrode.
2. 2. The method of manufacturing an ultrasonic probe according to claim 1, wherein a complete reflection layer is provided on a surface of the piezoelectric body that faces the surface on which the subject is located.

3 . 3. The method for manufacturing an ultrasonic probe according to claim 1 or 2 , wherein the thickness of the electrode is within a range of 0.01 to 1% of the thickness of the piezoelectric body.

4 . The thickness of the contact bonding layer which adhere | attaches the said piezoelectric material and the said acoustic matching layer is in the range of 0.01 to 5% of the thickness of the said piezoelectric material , Any one of the said 1st to 3rd items. A method for producing the ultrasonic probe according to 1.

By means of the above-mentioned means of the present invention, even when a single crystal or the like that is a piezoelectric body causes chipping during array-shaped cutting (dicing), there is no fear of conduction failure due to electrode peeling, and reliable conduction can be ensured, And the manufacturing method of an ultrasonic probe with a high yield of a manufacturing process can be provided .

Schematic diagram showing a configuration example of an ultrasound probe Schematic diagram showing a configuration example of an ultrasound probe Example in which electrode is provided on layer or member adjacent to piezoelectric body Example in which electrode is provided on layer or member adjacent to piezoelectric body The figure explaining the pattern obtained by X-ray diffraction: (A) is a pattern in the case of <100> single crystal, (B) is a pattern in the case of <100> uniaxially oriented crystal Schematic diagram showing the external configuration of an ultrasonic medical diagnostic imaging apparatus Block diagram showing the electrical configuration of the ultrasonic medical diagnostic imaging apparatus Schematic diagram showing the configuration of the GND printed flexible printed circuit board (the part connected to the cable is omitted) Example in which electrode is provided on layer or member adjacent to piezoelectric body

  The ultrasonic probe of the present invention is an ultrasonic probe in which an acoustic lens, an acoustic matching layer, an ultrasonic transducer, and a backing layer are bonded and laminated in this order, and the ultrasonic transducer The piezoelectric body constituting the substrate is a single crystal or a uniaxially oriented crystal, and an electrode is provided only on a layer or member adjacent to the piezoelectric body. This feature is a technical feature common to the inventions according to claims 1 to 5.

  As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the thickness of the electrode provided on the layer or member adjacent to the piezoelectric body is 0.01 to 1% of the thickness of the piezoelectric body. It is preferable to be within the range. Moreover, it is preferable that the thickness of the adhesive layer which adhere | attaches the layer or member which adjoins the said piezoelectric material exists in the range of 0.01-5% of the thickness of the said piezoelectric material.

  Furthermore, an acoustic lens, an acoustic matching layer, an ultrasonic transducer, and a backing layer are bonded and laminated in this order, and the piezoelectric body constituting the ultrasonic transducer is a single crystal or a uniaxially oriented crystal. The manufacturing method of the acoustic probe needs to be a manufacturing method in which an electrode is provided only on a layer or member adjacent to the piezoelectric body.

  The ultrasonic probe of the present invention can be suitably used for an ultrasonic medical image diagnostic apparatus.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

(Outline of ultrasonic probe)
The ultrasonic probe according to the present invention is a main component of an ultrasonic diagnostic imaging apparatus and the like, and has a function of generating ultrasonic waves and transmitting / receiving ultrasonic beams. The internal configuration of the ultrasonic probe can take various forms. As a basic configuration, an acoustic lens, an acoustic matching layer, an ultrasonic transducer, and a backing layer are bonded and laminated in this order. The piezoelectric body constituting the ultrasonic transducer is a single crystal or a uniaxially oriented crystal, and an electrode is provided on a layer or member adjacent to the piezoelectric body. Features.

  As a preferred embodiment, the “acoustic lens”, “acoustic matching layer”, “GND pull-out flexible printed circuit board”, “piezoelectric body”, “electrode” are provided from the tip (surface contacting the living body as the subject). It is possible to adopt a configuration of a mode in which signals are drawn in the order of “signal extraction flexible printed circuit board” and “backing layer” (see FIGS. 1 and 2).

  In the present application, the “layer or member adjacent to the piezoelectric body” refers to an acoustic matching layer, a backing layer, a complete reflection layer (also referred to as “dematching layer”), a flexible printed circuit board, and the like.

  Accordingly, various modes can be adopted as the mode in which the electrode is provided on the layer or member adjacent to the piezoelectric body. For example, it is preferable to adopt the mode shown in FIGS. In the figure, only a part of the adhesive layer between the layers is shown, and the other adhesive layers are not shown.

(Acoustic lens)
The acoustic lens according to the present invention is arranged to focus an ultrasonic beam using refraction and improve resolution. That is, the acoustic lens is provided on the side of the ultrasonic probe that comes into contact with the subject, and the ultrasonic wave generated by the piezoelectric body is efficiently incident on the subject. The acoustic lens has a convex lens shape in contact with the subject, and converges the ultrasonic wave incident on the subject in the thickness direction perpendicular to the imaging section.

  The acoustic lens is generally formed of a soft material having an acoustic impedance intermediate between the subject and the acoustic matching layer.

  The material constituting the acoustic lens includes conventionally known homopolymers such as silicone rubber, fluorosilicone rubber, polyurethane rubber and epichlorohydrin rubber, and copolymers such as ethylene-propylene copolymer rubber obtained by copolymerizing ethylene and propylene. A combined rubber or the like can be used. Of these, it is preferable to use silicone rubber.

  Examples of the silicone rubber used in the present invention include silicone rubber and fluorine silicone rubber. In particular, it is preferable to use silicone rubber because of the characteristics of the lens material. Silicone rubber is an organopolysiloxane having a molecular skeleton composed of Si—O bonds, and having a plurality of organic groups mainly bonded to the Si atoms. Usually, the main component is methylpolysiloxane, and the entire organic group is organic. 90% or more of the groups are methyl groups. A material in which a hydrogen atom, a phenyl group, a vinyl group, an allyl group or the like is introduced instead of the methyl group can also be used. The silicone rubber can be obtained, for example, by kneading a curing agent (vulcanizing agent) such as benzoyl peroxide with organopolysiloxane having a high degree of polymerization, followed by heat vulcanization and curing. If necessary, organic or inorganic fillers such as silica and nylon powder, and vulcanization aids such as sulfur and zinc oxide may be added.

  Examples of the butadiene rubber used in the present invention include butadiene alone or a copolymer rubber mainly composed of butadiene and copolymerized with a small amount of styrene or acrylonitrile. In particular, it is preferable to use butadiene rubber because of the characteristics of the lens material. The butadiene rubber refers to a synthetic rubber obtained by polymerization of butadiene having a conjugated double bond. Butadiene rubber can be obtained by 1.4 or 1.2 polymerization of butadiene alone having a conjugated double bond. A butadiene rubber vulcanized with sulfur or the like can be used.

  The acoustic lens according to the present invention can be obtained by mixing and curing and curing silicone rubber and butadiene rubber. For example, it can be obtained by mixing silicone rubber and butadiene rubber in an appropriate ratio by a kneading roll, adding a vulcanizing agent such as benzoyl peroxide, and heat vulcanizing and crosslinking (curing). At that time, it is preferable to add zinc oxide as a vulcanization aid. Zinc oxide can accelerate vulcanization and shorten the vulcanization time without deteriorating lens characteristics. In addition, other additives may be added as long as the characteristics of the colorant and the acoustic lens are not impaired. The mixing ratio of the silicone rubber and the butadiene rubber is preferably 1: 1 in order to obtain a material whose acoustic impedance is close to that of the human body and whose sound speed is smaller than that of the human body and less attenuated. The mixing ratio can be changed as appropriate.

  Silicone rubber can be obtained as a commercial product. For example, KE742U, KE752U, KE931U, KE941U, KE951U, KE961U, KE850U, KE555U, KE575U, etc. manufactured by Shin-Etsu Chemical Co., Ltd., TSE221-3U, TE221 manufactured by Momentive Performance Materials, Inc. -4U, TSE2233U, XE20-523-4U, TSE27-4U, TSE260-3U, TSE-260-4U, SH35U, SH55UA, SH831U, SE6749U, SE1120USE4704U manufactured by Dow Corning Toray can be used.

  In the present invention, an inorganic filler such as silica, alumina, titanium oxide, nylon, etc., depending on the purpose of adjusting the speed of sound, adjusting the density, etc., based on the rubber material such as the above-mentioned silicone rubber (main component) An organic resin or the like can also be blended.

(Acoustic matching layer)
The acoustic matching layer according to the present invention matches the acoustic impedance between the ultrasonic transducer and the subject. In other words, the acoustic matching layer is attached to a subject-side plate surface that is a transmission / reception direction in which transmission / reception of a piezoelectric body is performed. The acoustic matching layer has an acoustic impedance substantially intermediate between that of the piezoelectric body and the acoustic lens. The acoustic matching layer has a thickness of approximately a quarter wavelength of the transmitted ultrasonic wave in the transmission / reception direction of the subject, and suppresses reflection at a boundary surface having different acoustic impedance.

  Materials used for the acoustic matching layer include aluminum, aluminum alloy (for example, AL-Mg alloy), magnesium alloy, Macor glass, glass, fused quartz, copper graphite, polyethylene (PE), polypropylene (PP), and polycarbonate (PC). , ABC resin, polyphenylene ether (PPE), ABS resin, AAS resin, AES resin, nylon (PA6, PA6-6), PPO (polyphenylene oxide), PPS (polyphenylene sulfide: glass fiber can be included), PPE (polyphenylene ether) ), PEEK (polyetheretherketone), PAI (polyamideimide), PETP (polyethylene terephthalate), PC (polycarbonate), epoxy resin, urethane resin, and the like. Preferably, a thermosetting resin such as an epoxy resin is molded by adding zinc white, titanium oxide, silica, alumina, bengara, ferrite, tungsten oxide, yttrium oxide, barium sulfate, tungsten, molybdenum, etc. as a filler. Can be used.

  The acoustic matching layer may be a single layer or may be composed of a plurality of layers, but is preferably 2 layers or more, more preferably 4 layers or more. The thickness of the acoustic matching layer is preferably determined to be λ / 4 where λ is the wavelength of the ultrasonic wave. If this is not satisfied, a plurality of unnecessary spurious noises may appear at a frequency point different from the original resonance frequency, and the basic acoustic characteristics may vary greatly. As a result, reverberation time increases and sensitivity and S / N decrease due to waveform distortion of the reflected echo are undesirable. The thickness of such an acoustic matching layer is generally in the range of 20 to 500 μm.

(Ultrasonic vibrator: piezoelectric element)
In general, an “ultrasonic transducer” refers to an element having an electrode and a piezoelectric body, capable of converting electrical signals into mechanical vibrations and converting mechanical vibrations into electrical signals and capable of transmitting and receiving ultrasonic waves. .

  However, the ultrasonic probe of the present invention is characterized in that the piezoelectric body and the electrodes provided in the adjacent layers or members in contact with the piezoelectric body are integrated so as to function as an ultrasonic transducer.

(Piezoelectric)
The piezoelectric body has a function of generating an ultrasonic wave, inputting the ultrasonic wave to the subject, and simultaneously receiving an ultrasonic echo reflected inside the subject. That is, the piezoelectric body is made of a substance such as a crystal that can convert an electrical signal into mechanical vibration and convert mechanical vibration into an electrical signal.

  The present invention is characterized by using a piezoelectric material of a single crystal or a uniaxial crystal as the piezoelectric material.

  In the present application, “single crystal” refers to a crystal having a single crystal orientation in the film thickness direction and the in-plane direction. For example, a <100> single crystal is a film composed of crystals having a film thickness direction only in the <100> orientation and one in-plane direction having only the <110> orientation. Whether the piezoelectric film is a uniaxially oriented crystal can be confirmed using X-ray diffraction. For example, in the case of a <100> single crystal having a PZT perovskite structure, peaks due to the piezoelectric film in 2θ / θ measurement of X-ray diffraction are (L00) planes such as {100} and {200} (L = 1, 2, 3... N: n is an integer) only. Further, when measuring the extreme point of the {110} asymmetric surface, as shown in FIG. 5 (A), a spot-like pattern which is symmetric four times every 90 ° is obtained at the same radial position representing an inclination of about 45 ° from the center. It is done.

  The “uniaxially oriented crystal” refers to a crystal having a single crystal orientation in the film thickness direction, and the in-plane orientation of the crystal is not particularly limited. For example, a <100> uniaxially oriented crystal is a film composed of crystals having a film thickness direction only in the <100> orientation. Whether the piezoelectric film is a uniaxially oriented crystal can be confirmed using X-ray diffraction. For example, in the case of a <100> uniaxially oriented crystal having a PZT perovskite structure, peaks due to the piezoelectric film in 2θ / θ measurement of X-ray diffraction are (L00) planes such as {100} and {200} (L = 1 , 2, 3... N: n is an integer) only peaks are detected. Further, when the pole measurement of the {110} asymmetric surface is performed, a ring-shaped pattern is obtained at the same radial position representing an inclination of about 45 ° from the center as shown in FIG.

  For example, in a PZT perovskite structure with <100> orientation, when measuring the pole of a {110} asymmetric surface, an 8-fold or 12-fold symmetric pattern is formed at the same radial position representing an inclination of about 45 ° from the center. Some crystals are obtained. Alternatively, some crystals have an oval pattern instead of a spot. These crystals are also crystals having an intermediate symmetry between the single crystal of the present invention and the uniaxially oriented crystal, and thus are regarded as a single crystal and a uniaxially oriented crystal in a broad sense.

  Similarly, for example, when multiple crystal phases such as monoclinic and tetragonal, monoclinic and rhombohedral, tetragonal and rhombohedral, etc. are mixed (mixed phase), or crystals due to twins are mixed When there is a dislocation or a defect, it is regarded as a single crystal and a uniaxially oriented crystal in a broad sense. Here, the term “mixed with several crystal phases” (mixed phases) does not mean that a plurality of crystal phases have different crystal axis directions and have a grain boundary in a polycrystalline state. That is, a plurality of crystal phases are present in one particle of a perovskite oxide, and are integrally formed into a single crystal or a uniaxial orientation.

Examples of the piezoelectric crystal that can be used in the present invention include lead zinc niobate and lead titanate represented by Pb ((Zn _1/3 Nb _2/3 ) _0.91 Ti _0.09 ) O _3. Single crystal (PMN-PT), scandium niobium, which is a complex perovskite type containing at least lead titanate, such as a single crystal (PZN-PT) comprising a solid solution of magnesium, lead niobate and lead titanate Examples thereof include a single crystal composed of a solid solution of lead oxide and lead titanate, and a solid solution single crystal composed of indium / lead niobate and lead titanate. Single crystals such as lithium niobate and potassium niobate may also be used.

  The piezoelectric body according to the present invention can be manufactured by a manufacturing method such as a melt flux method or a Bridgman method used as a manufacturing method of a single crystal material.

  In addition, examples of the method for producing a piezoelectric body according to the present invention include generally referred to thin film deposition methods such as a sol-gel method, a hydrothermal synthesis method, a sputtering method, an MBE method, a PLD method, a CVD method, and an MO-CVD method. . These thin film forming methods are suitable for forming a film thickness on the order of several nm to 10 μm. For these production methods, JP-A-2007-88443, JP-A-2007-88444, JP-A-2007-88447 and the like can be referred to.

  The thickness of the piezoelectric body according to the present invention is generally in the range of 100 nm to 500 μm.

(electrode)
The electrode is for applying a voltage to the single crystal piezoelectric body, and is grounded from the electrode through a ground (GND) through a flexible printed board.

  The signal drawing flexible printed circuit board is provided below the single crystal piezoelectric body and includes an electrode for applying a voltage.

  The ultrasonic probe according to the present invention is characterized in that the electrode is not directly attached to the piezoelectric body with an adhesive or the like, and the electrode is provided only on a layer or a member adjacent to the piezoelectric body.

  As an aspect in which the electrode is provided only in the layer or member adjacent to the piezoelectric body, the electrode is preferably provided in an acoustic matching layer, a backing layer, a complete reflection layer (also referred to as “dematching layer”), or the like. For example, in the configuration shown in FIGS. 2 to 4, it is preferable to adopt a mode in which electrodes are provided on the acoustic matching layer, the complete reflection layer, and the like.

  Examples of the material used for the electrode include gold (Au), platinum (Pt), silver (Ag), palladium (Pd), copper (Cu), aluminum (Al), nickel (Ni), tin (Sn), and the like. It is done. In forming the electrode, first, after forming a base metal such as titanium (Ti) or chromium (Cr) to a thickness of 0.002 to 1.0 μm by sputtering, the metal mainly composed of the above metal elements and those A metal material made of the above alloy, and further, if necessary, a part of the insulating material is formed to a thickness of 1 to 10 μm by sputtering, vapor deposition or other suitable methods. In addition to sputtering, these electrodes can be formed by screen printing, dipping, or thermal spraying using a conductive paste in which fine metal powder and low-melting glass are mixed.

  As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the thickness of the electrode provided on the layer or member adjacent to the piezoelectric body is 0.01 to 1% of the thickness of the piezoelectric body. It is preferable to be within the range.

  In addition, although not employ | adopted in this invention, also as a method of attaching an electrode to a piezoelectric material, it can attach using the same method.

(Fully reflective layer)
In the present invention, when making the ultrasonic transducer perform ¼ wavelength resonance, the ultrasonic transducer plate surface opposite to the plate surface on the side where the subject is located is placed on the ultrasonic transducer plate. An impedance complete reflection layer (“dematching layer”; also referred to as “DE-MATCHING LAYER” or “DML”) may be provided.

  The complete reflection layer is a reflection layer that completely reflects the elastic vibration generated by the ultrasonic vibrator, and is adhered to a plate surface in a direction opposite to the irradiation direction of the ultrasonic vibrator. The complete reflection layer completely reflects the ultrasonic wave of the ultrasonic transducer irradiated in the direction opposite to the direction of the subject in the irradiation direction of the subject and increases the ultrasonic power incident on the subject. The material of the complete reflection layer is preferably one having high acoustic impedance for the purpose of completely reflecting ultrasonic waves, and tungsten (tungsten) or the like is used.

(Backing layer)
The backing layer is an ultrasonic absorber that supports an ultrasonic transducer (piezoelectric element) and can absorb unnecessary ultrasonic waves. That is, the backing layer is mounted on a plate surface opposite to the direction in which sound waves are transmitted to and received from the piezoelectric object, and absorbs ultrasonic waves generated from the opposite side of the object direction.

  The backing material that constitutes the backing layer includes natural rubber, ferrite rubber, epoxy resin containing powders of tungsten oxide, titanium oxide, ferrite, etc., press molding, vinyl chloride, polyvinyl butyral (PVB), ABS resin, polyurethane (PUR), polyvinyl alcohol (PVAL), polyethylene (PE), polypropylene (PP), polyacetal (POM), polyethylene terephthalate (PET), fluororesin (PTFE) polyethylene glycol, polyethylene terephthalate-polyethylene glycol copolymer, etc. A plastic resin or the like can be used.

  A preferable backing material is made of a rubber-based composite material and / or an epoxy resin composite material, and the shape thereof can be appropriately selected according to the shape of the piezoelectric body or the probe head including the piezoelectric body.

(Flexible printed circuit board)
A flexible printed circuit board (also referred to as a “flexible wiring board”) is provided at one end (a part) of an acoustic matching layer or a backing layer, and is a signal extraction flexible printed circuit board having an electrode for applying power to a piezoelectric body. And a ground (GND) lead flexible printed circuit board for earth connection.

  As a material for the flexible printed circuit board, metallic copper (Cu) can be used for the conductive layer based on a resin such as polyimide.

(Adhesive layer)
In the present invention, the various functional layers and members are preferably laminated via an adhesive layer. As an adhesive for forming the adhesive layer, an epoxy resin-based or acrylic resin-based adhesive can be used. Specific examples of commercially available epoxy adhesives include DP-420, DP-460, DP-460EG manufactured by 3M Company, Excel Epo manufactured by Cemedine, EP001, EP008, EP330, EP331, Huntsman Advanced Materials, Inc. Araldite Standard, Araldite Rapid, System Three Epoxy from System Three, Gel Magic, 2087L (High-strength two-part epoxy compounded resin), 2082C (High-temperature two-part epoxy resin high shear adhesive strength) Type), 2081D (adhesive epoxy system for soft vinyl chloride), E-set L manufactured by Konishi, Duralco 4525IP, 7050, NM25, 4461IP manufactured by Kotronics. Moreover, in this invention, you may use a conductive adhesive as an adhesive agent which adhere | attaches a single crystal piezoelectric material and the adjacent layer to which the electrode was provided. Using epoxy resin, acrylic, urethane, polyimide, other thermosetting resin or thermoplastic resin as a binder, gold powder, silver powder, copper powder, nickel powder, aluminum powder, plating powder, carbon powder, graphite powder, etc. are used for the conductive filler. The conductive adhesive that has been used can be used. As the filler shape, various shapes such as flake shape, spherical shape, and dendritic shape can be taken. The conductivity of the conductive adhesive, it is preferable to use those ¹⁰ -1 ^{~10 -5 Ω} · cm range volume resistivity.

  As an embodiment of the present invention, from the viewpoint of manifesting the effects of the present invention, the thickness of the adhesive layer that bonds the piezoelectric body and the adjacent layer or member is 0.01 to 5% of the thickness of the piezoelectric body. It is preferable to be within the range. More preferably, it is 1 μm or less.

(Ultrasonic medical diagnostic imaging equipment)
The ultrasonic probe of the present invention can be used in various forms of ultrasonic medical image diagnostic apparatuses (also referred to as “ultrasonic diagnostic apparatuses”).

  FIG. 6 is a schematic diagram illustrating an external configuration of the ultrasonic diagnostic apparatus according to the embodiment. FIG. 7 is a block diagram illustrating an electrical configuration of the ultrasonic diagnostic apparatus according to the embodiment.

  As shown in FIGS. 6 and 7, the ultrasound diagnostic apparatus S transmits an ultrasound signal (hereinafter also referred to as “first ultrasound signal”) to a subject H such as a living body (not shown). The ultrasonic probe 2a that receives the reflected wave of the ultrasonic signal reflected by the subject H (hereinafter also referred to as “second ultrasonic signal”), and is connected via the ultrasonic probe 2a and the cable 3a. The ultrasonic probe 2a transmits the first ultrasonic signal to the subject H by transmitting an electric signal transmission signal to the ultrasonic probe 2a via the cable 3a, and at the same time, the ultrasonic probe Based on the received signal of the electrical signal generated by the ultrasonic probe 2a in accordance with the second ultrasonic signal from the subject H received by the child 2a, the internal state in the subject H is converted into an ultrasonic image. And an ultrasonic diagnostic apparatus main body 1a for imaging a medical image. The ultrasonic diagnostic apparatus main body 1a is provided with an ultrasonic probe folder 4a that holds the ultrasonic probe 2a when the ultrasonic probe 2a is not used.

  For example, as shown in FIG. 7, the ultrasonic diagnostic apparatus main body 1a includes an operation input unit 11a, a transmission unit 12a, a reception unit 13a, a signal processing unit 14a, an image processing unit 15a, a display unit 16a, The control part 17a, the memory | storage part 19a, and the voltage control means 18a are provided and comprised.

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

  The transmission unit 12a is a circuit having a function of generating a transmission signal of an electrical signal that drives a first piezoelectric unit and a second piezoelectric unit, which will be described later, under the control of the control unit 17a. The transmitting unit 12a supplies a transmission signal to the first piezoelectric unit and the second piezoelectric unit in the ultrasonic probe 2a via the voltage control unit 18a and the cable 3a, and the first probe is supplied to the ultrasonic probe 2a. An ultrasonic signal is generated. The transmission unit 12a includes, for example, a high voltage pulse generator that generates a high voltage pulse.

  The receiving unit 13a is a circuit that receives a reception signal of an electrical signal from the ultrasonic probe 2a via the cable 3a according to the control of the control unit 17a, and outputs the received signal to the signal processing unit 14a. The reception unit 13a includes, for example, an amplifier that amplifies the reception signal with a predetermined amplification factor set in advance, an analog-digital converter that converts the reception signal amplified by the amplifier from an analog signal to a digital signal, and the like. Configured.

  The signal processing unit 14a is a circuit that performs predetermined signal processing on the electrical signal from the receiving unit 13a in accordance with the control of the control unit 17a, and outputs the reflected reception signal subjected to the signal processing to the image processing unit 15a.

  Under the control of the control unit 17a, the image processing unit 15a generates an ultrasonic image of the internal state in the subject H using, for example, a harmonic imaging technique based on the reflected reception signal signal-processed by the signal processing unit 14a. Circuit. For example, a B-mode signal corresponding to the amplitude intensity of the second ultrasonic signal is generated by performing envelope detection processing on the reflected reception signal.

  The storage unit 19a is constituted by a RAM or a ROM, in which programs used for the control unit 17a are recorded, and various image templates to be displayed on the display unit 16a are recorded.

  The voltage control unit 18a has a function of controlling how the transmission signal of the electrical signal from the transmission unit 12a is applied to the first piezoelectric unit and the second piezoelectric unit in accordance with the control of the control unit 17a. .

  The display unit 16a is a device that displays the ultrasonic image generated by the image processing unit 15a under the control of the control unit 17a. The display unit 16a is, for example, a display device such as a CRT display, LCD, EL display, or plasma display, or a printing device such as a printer.

  The control unit 17a includes, for example, a microprocessor, a storage element, and peripheral circuits thereof. The operation input unit 11a, the transmission unit 12a, the reception unit 13a, the signal processing unit 14a, the image processing unit 15a, a voltage control unit, and the like. This is a circuit that performs overall control of the ultrasonic diagnostic apparatus S by controlling the 18a and the storage unit 19a in accordance with the function.

  On the other hand, the ultrasound probe 2a includes a vibrating unit 30a. The vibrating unit 30a transmits a first ultrasonic signal to a subject H such as a living body (not shown), and from the subject H. The second ultrasonic signal is received. The vibration unit 30a includes, for example, a backing layer (acoustic braking member), a piezoelectric layer, an acoustic matching layer, and an acoustic lens.

  The backing layer (acoustic braking member) is a flat plate member made of a material that absorbs ultrasonic waves, and absorbs ultrasonic waves emitted from the piezoelectric layer toward the backing layer (acoustic braking member).

  The piezoelectric layer includes a piezoelectric material, and converts signals between an electric signal and an ultrasonic signal by using a piezoelectric phenomenon. Electrodes are formed on both sides of the piezoelectric layer. The piezoelectric layer may have a configuration in which two layers of a first piezoelectric layer and a second piezoelectric layer are stacked.

  The piezoelectric layer converts a transmission electrical signal input from the transmission unit 12a of the ultrasonic diagnostic apparatus main body 1a via the cable 3a into a first ultrasonic signal, transmits the first ultrasonic signal, and receives the received first signal. 2 The ultrasonic signal is converted into an electric signal, and this electric signal (reception signal) is output to the receiving unit 13a of the ultrasonic diagnostic apparatus main body 1a via the cable 3a. When the ultrasonic probe 2a is brought into contact with the subject H, the first ultrasonic signal generated by the piezoelectric layer 5 is transmitted into the subject H, and the second ultrasonic signal from within the subject H is transmitted. Received at the piezoelectric layer.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1
A method for manufacturing the ultrasonic probe according to the present embodiment will be described with reference to FIG.

First, an acoustic matching layer 10 made of an epoxy resin in which alumina powder is dispersed, having a thickness of 150 μm, provided with a Ni / Au electrode 11 on the surface to be bonded to the single crystal piezoelectric material side (acoustic impedance: 2). .5 × 10 ⁶ kg / m ² · s).

  Thereafter, the GND lead-out flexible printed circuit board 12 is uniformly pressed and heated on the acoustic matching layer 10 and bonded using an epoxy adhesive DP-460 (manufactured by Sumitomo 3M). Note that the surface side to be bonded to the single crystal piezoelectric body can be kept flat by uniformly applying pressure and heat. In the flexible printed circuit board 12, the conductive layer 20 is exposed at the portion to be bonded to the acoustic matching layer, and as shown in FIG. 8, it is bonded to the concave portion of the acoustic matching layer at a portion having a width of about 1 mm. The flatness can be maintained after bonding. Further, the part drawn out to the outside is protected by a cover layer 21 made of polyimide resin or the like.

  Next, on the surface opposite to the ultrasonic irradiation side of the single crystal piezoelectric material, a flexible printed circuit board 14 that extends the conductive layer of the flexible printed circuit board (FPC) to the area of the piezoelectric material, and a backing material 15 ( Silicone rubber TSE2233U (made by Momentive Co., Ltd.) and ferrite fine particles added to an epoxy resin and kneaded and hardened) are bonded uniformly using an epoxy adhesive by pressing and heating uniformly in the thickness direction. To do.

  Thereafter, the formed acoustic matching layer, the single crystal piezoelectric body 13 having a thickness of 290 μm made of magnesium / lead niobate / lead titanate solid solution, and the backing provided with the formed signal extraction electrode are uniformly formed using the epoxy adhesive. Adhere by applying pressure and warming to. Before bonding each member, primer treatment is performed to improve adhesion.

  Next, by using a blade having a thickness of 30 μm by a dicing saw, the signal extraction flexible substrate is processed to be completely cut at a pitch of 200 μm in the array direction, thereby forming an element.

  Next, the prepared ultrasonic element was placed in a vacuum processing chamber, polychloroparaxylylene (Parylene C: Union Carbide, USA) was filled in the heating chamber and heated to vaporize at 150 ° C, and then further 680 ° C. Is thermally decomposed by vapor deposition in a vacuum processing chamber, an insulating film is formed with a thickness of 3 μm, and a groove is filled with a silicon-based adhesive, and then the acoustic lens 16 is pressurized and heated. Then, an ultrasonic probe is produced by bonding them.

  According to the ultrasonic probe manufactured by the above method, there is no fear of conduction failure due to electrode peeling even if single crystal is chipped by cutting the array shape, and reliable conduction can be ensured, and the manufacturing process The yield can be improved.

Example 2
In Example 2, a case where a complete reflection layer (also referred to as “DML” or “dematching layer”) is provided below a single crystal piezoelectric body will be described.

  The components already described in FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. Moreover, the description which overlaps with the manufacturing method described in 1st Embodiment is abbreviate | omitted, and only a different part is demonstrated.

  A second embodiment will be described with reference to FIG. The method of adhering to the acoustic matching layer 10 to the GND lead flexible printed circuit board 12 is the same as described above.

  Next, the backing material 15, the signal drawing flexible printed circuit board 14, and the complete reflective layer (DML) 17 made of tungsten carbide are uniformly pressed and heated in the thickness direction in order, and an epoxy adhesive is used. Glue. The DML 17 is mirror-polished in advance on the surface to be bonded to the single crystal piezoelectric body so that it can be uniformly bonded, and the electrode 18 is formed by using the above-described method. Since DML 17 has conductivity, it may be used without providing an electrode.

  Thereafter, the formed acoustic matching layer, the 150 μm-thick single crystal piezoelectric body 13 made of magnesium / lead niobate / lead titanate solid solution, and the surface of the DML are uniformly pressurized and heated with an epoxy adhesive. The ultrasonic probe is manufactured by the same method as described above except that the bonding is performed.

  According to the ultrasonic probe manufactured by the above method, the same effect as in the first embodiment can be obtained.

  Also, as shown in FIG. 4, an electrode may be provided on the side surface of the acoustic matching layer to bring the GND-extracted flexible printed circuit board to the upper part of the acoustic matching layer. Also, as shown in FIG. A flexible printed board 22 in which the conductive layer of the board is expanded to the area of the piezoelectric body may be used, and the same effect as in the first embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Single crystal piezoelectric material 2 Acoustic matching layer 3 Acoustic lens 4 Backing layer 5 Electrode 6 Electrode 7 Flexible printed circuit board (FPC)
DESCRIPTION OF SYMBOLS 10 Acoustic matching layer 11 Ni / Au electrode 12 GND drawer flexible printed circuit board 13 Single crystal piezoelectric material 14 Signal extraction flexible printed circuit board 15 Backing material 16 Acoustic lens 17 Complete reflection layer (DML)
18 electrodes (Ni / Au electrodes)
19 Adhesive layer 20 Conductive layer 20
DESCRIPTION OF SYMBOLS 21 Cover layer 22 GND drawer flexible printed circuit board 1a Ultrasonic medical image diagnostic apparatus main body 2a Ultrasonic probe 3a Cable 4a Ultrasonic probe folder 11a Operation input part 12a Transmission part 13a Reception part 14a Signal processing part 15a Image processing part 16a Display unit 17a Control unit 18a Voltage control means 19a Storage unit 30a Vibration unit

Claims (4)

A method of manufacturing an ultrasonic probe in which a piezoelectric body that is a single crystal or a uniaxially oriented crystal and an acoustic matching layer are stacked via electrodes,
Forming the electrode by vapor deposition or sputtering only on the surface of the acoustic matching layer;
A step of bonding the acoustic matching layer on which the electrode is formed and the piezoelectric body via the electrode; 2. The method of manufacturing an ultrasonic probe according to claim 1, wherein a complete reflection layer is provided on a surface of the piezoelectric body that faces the surface on which the subject is located. The method of manufacturing an ultrasonic probe according to claim 1 or 2 , wherein a thickness of the electrode is in a range of 0.01 to 1% of a thickness of the piezoelectric body. The thickness of the contact bonding layer which adhere | attaches the said piezoelectric material and the said acoustic matching layer exists in the range of 0.01 to 5% of the thickness of the said piezoelectric material, The Claim 1 to 3 Manufacturing method of ultrasonic probe.

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