WO2023223955A1 - Piezoelectric element and ultrasonic transducer - Google Patents

Piezoelectric element and ultrasonic transducer Download PDF

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Publication number
WO2023223955A1
WO2023223955A1 PCT/JP2023/017878 JP2023017878W WO2023223955A1 WO 2023223955 A1 WO2023223955 A1 WO 2023223955A1 JP 2023017878 W JP2023017878 W JP 2023017878W WO 2023223955 A1 WO2023223955 A1 WO 2023223955A1
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WIPO (PCT)
Prior art keywords
piezoelectric element
outer edge
piezoelectric
lower electrode
electrode
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PCT/JP2023/017878
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French (fr)
Japanese (ja)
Inventor
優作 清水
悠佑 長田
清 山腰
隆文 福井
清彦 河野
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パナソニックIpマネジメント株式会社
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Publication of WO2023223955A1 publication Critical patent/WO2023223955A1/en

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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04RLOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00Piezoelectric transducers; Electrostrictive transducers
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00Piezoelectric or electrostrictive devices
    • H10N30/20Piezoelectric or electrostrictive devices with electrical input and mechanical output, e.g. functioning as actuators or vibrators
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00Piezoelectric or electrostrictive devices
    • H10N30/30Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00Piezoelectric or electrostrictive devices
    • H10N30/80Constructional details
    • H10N30/85Piezoelectric or electrostrictive active materials
    • H10N30/853Ceramic compositions
    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00Piezoelectric or electrostrictive devices
    • H10N30/80Constructional details
    • H10N30/88Mounts; Supports; Enclosures; Casings

Definitions

  • the present disclosure relates to a piezoelectric element and an ultrasonic transducer, and more particularly to a piezoelectric element having a lower electrode and an upper electrode, and an ultrasonic transducer including the piezoelectric element.
  • Patent Document 1 describes an aerial ultrasonic transmitter/receiver using a piezoelectric element, which includes a piezoelectric ceramic, a silver electrode formed by sintering conductive paste provided on both sides of the piezoelectric ceramic, and a bottomed cylindrical case.
  • An ultrasonic transmitter/receiver (ultrasonic transducer) is disclosed.
  • An object of the present disclosure is to provide a piezoelectric element and an ultrasonic transducer that can increase the operating frequency of the piezoelectric element.
  • a piezoelectric element includes a metal substrate, a lower electrode, a piezoelectric layer, and an upper electrode.
  • the metal substrate contains at least iron and chromium.
  • the lower electrode is provided on the metal substrate.
  • the piezoelectric layer is provided on the lower electrode.
  • the upper electrode is provided on the piezoelectric layer.
  • the first outer edge of the lower electrode is located inside the second outer edge of the metal substrate.
  • the third outer edge of the piezoelectric layer is located inside the first outer edge of the lower electrode.
  • the fourth outer edge of the upper electrode is located inside the third outer edge of the piezoelectric layer.
  • An ultrasonic transducer includes the piezoelectric element, a diaphragm section, a first conductive member, a second conductive member, a first conductive joint, a second conductive joint, Equipped with.
  • the diaphragm portion is joined to the metal substrate of the piezoelectric element.
  • the first conductive member is connected to the lower electrode of the piezoelectric element.
  • the second conductive member is connected to the upper electrode of the piezoelectric element.
  • the first conductive joint portion joins the lower electrode and the first conductive member.
  • the second conductive joint portion joins the upper electrode and the second conductive member.
  • FIG. 1 is a plan view of a piezoelectric element according to a first embodiment.
  • FIG. 2 is a sectional view taken along line A1-A1 in FIG. 1 regarding the piezoelectric element same as above.
  • FIG. 3 is an explanatory diagram of a method of manufacturing the same piezoelectric element as above.
  • FIG. 4 is a plan view of an ultrasonic transducer including the same piezoelectric element as above.
  • FIG. 5 is a cross-sectional view taken along the line A2-A2 in FIG. 4 regarding an ultrasonic transducer including the piezoelectric element mentioned above.
  • FIG. 6 is a plan view of the piezoelectric element according to the second embodiment.
  • FIG. 7 is a sectional view taken along line A3-A3 in FIG.
  • FIG. 8 is a plan view of an ultrasonic transducer including the same piezoelectric element as above.
  • FIG. 9 is a sectional view taken along the line A4-A4 in FIG. 8 regarding an ultrasonic transducer including the piezoelectric element mentioned above.
  • FIG. 10 is a plan view of a piezoelectric element according to Embodiment 3.
  • FIG. 11 is a sectional view taken along line A5-A5 in FIG. 10 regarding the piezoelectric element same as above.
  • FIG. 12 is a sectional view of an ultrasonic transducer according to Embodiment 4.
  • the piezoelectric element 1 includes a metal substrate 2, an alumina layer 3, a lower electrode 4, a piezoelectric layer 5, and an upper electrode 6. , is provided.
  • Metal substrate 2 contains at least iron and chromium.
  • the lower electrode 4 is provided on the metal substrate 2.
  • the piezoelectric layer 5 is provided on the lower electrode 4 .
  • the upper electrode 6 is provided on the piezoelectric layer 5.
  • the outer edge of the piezoelectric element 1 has, for example, a square shape.
  • “In plan view” has the same meaning as "as seen from above the metal substrate 2 in the direction along the thickness direction of the metal substrate 2.” In other words, "in plan view” has the same meaning as "in plan view from the thickness direction of the metal substrate 2.”
  • the ultrasonic transducer 100 includes a piezoelectric element 1, a diaphragm section 120, a first lead wire 141, a second lead wire 142, a first conductive joint 131, and a first conductive joint 131. 2 conductive joint portion 132.
  • the first lead wire 141 constitutes a first conductive member
  • the second lead wire 142 constitutes a second conductive member.
  • the diaphragm section 120 is joined to the metal substrate 2 of the piezoelectric element 1. More specifically, the diaphragm section 120 is joined to the metal substrate 2 of the piezoelectric element 1 by the joining section 105.
  • the first lead wire 141 is connected to the lower electrode 4 of the piezoelectric element 1 .
  • the second lead wire 142 is connected to the upper electrode 6 of the piezoelectric element 1 .
  • the first conductive joint 131 joins the lower electrode 4 and the first lead wire 141.
  • the second conductive joint 132 joins the upper electrode 6 and the second lead wire 142.
  • the ultrasonic transducer 100 transmits ultrasonic waves by converting a first electric signal (AC voltage with a predetermined drive frequency) into a first mechanical vibration in the piezoelectric element 1.
  • a first electric signal AC voltage with a predetermined drive frequency
  • the diaphragm part 120 vibrates in the vertical direction due to the horizontal expansion and contraction movement of the piezoelectric element 1. It vibrates in the thickness direction, and ultrasonic waves are transmitted.
  • the ultrasonic transducer 100 includes, for example, a piezoelectric element 1 that accompanies vibration in the thickness direction of the diaphragm section 120 when a reflected wave of an ultrasonic wave transmitted from the ultrasonic transducer 100 is incident on the diaphragm section 120. is converted into a second electrical signal in the piezoelectric element 1.
  • the diaphragm portion 120 has a flat plate shape.
  • the ultrasonic transducer 100 further includes a case 101 housing the piezoelectric element 1.
  • Case 101 has a bottom plate portion 102 and a cylinder portion 103.
  • the bottom plate portion 102 has a flat plate shape.
  • the cylindrical portion 103 protrudes from the periphery of one surface of the bottom plate portion 102 in the thickness direction of the bottom plate portion 102 and surrounds the piezoelectric element 1 .
  • a portion of the bottom plate portion 102 surrounded by the cylindrical portion 103 also serves as a diaphragm portion 120.
  • the ultrasonic transducer 100 includes a sound absorbing member 150 disposed above the piezoelectric element 1 in the case 101, and a sealing portion disposed on the sound absorbing member 150 in the case 101. 160. Note that in FIG. 4, illustration of the sound absorbing member 150 and the sealing part 160 is omitted.
  • the metal substrate 2 has a flat plate shape.
  • the metal substrate 2 has an upper surface (first main surface) 21 and a lower surface (second main surface) 22, as shown in FIG.
  • the outer edge 20 of the metal substrate 2 has, for example, a square shape (for example, a rectangular shape) in plan view.
  • the thickness of the metal substrate 2 is, for example, 0.1 mm, but is not limited thereto.
  • the metal substrate 2 contains iron, chromium, and aluminum.
  • the metal substrate 2 is a stainless steel substrate containing iron as a main component, and contains chromium and aluminum in addition to iron.
  • the stainless steel substrate constituting the metal substrate 2 is, for example, an aluminum-containing ferritic stainless steel substrate.
  • the aluminum-containing ferritic stainless steel substrate has, for example, a chromium content of 18 wt% and an aluminum content of 3 wt%.
  • the content of chromium is not limited to 18 wt%.
  • the aluminum content is not limited to 3 wt%.
  • the metal substrate 2 may further contain elements other than iron, chromium, and aluminum.
  • the alumina layer 3 is provided on the upper surface 21 (see FIG. 2) of the metal substrate 2. As shown in FIG. 1, the outer edge 30 of the alumina layer 3 has a square shape (for example, a rectangular shape) in plan view. The thickness of the alumina layer 3 is, for example, 1 ⁇ m, but is not limited thereto.
  • the main phase of alumina forming the alumina layer 3 is a ⁇ -alumina phase. That is, the alumina layer 3 is mainly formed of particles of ⁇ -alumina phase. "Mainly formed of ⁇ -alumina phase particles” means that more than 50% by weight of the alumina layer 3 is formed of ⁇ -alumina phase particles.
  • the crystalline phase of the material (particles) constituting the alumina layer 3 can be identified by measuring the X-ray diffraction pattern of the exposed portion of the alumina layer 3 using an X-ray diffraction device.
  • the upper surface of the alumina layer 3 includes a part of the surface of a plurality of scale-like particles of the alumina layer 3. Considering the SEM (Scanning Electron Microscope) image of the upper surface of the alumina layer 3 and the measurement results of the X-ray diffraction pattern, it is estimated that the scale-like particles are ⁇ -alumina particles.
  • the lower electrode 4 is provided on the upper surface 31 (see FIG. 2) of the alumina layer 3. As shown in FIG. 1, the outer edge 40 of the lower electrode 4 has, for example, a rectangular shape in plan view, but the shape is not limited to this.
  • the thickness of the lower electrode 4 is, for example, 3 ⁇ m, but is not limited thereto.
  • the material of the lower electrode 4 includes, for example, silver (Ag) and palladium (Pd). More specifically, the material of the lower electrode 4 includes, for example, an Ag--Pd alloy.
  • the piezoelectric layer 5 is provided on the upper surface 41 (see FIG. 2) of the lower electrode 4. As shown in FIG. 1, the outer edge 50 of the piezoelectric layer 5 has, for example, a rectangular shape in plan view, but the shape is not limited to this.
  • the thickness of the piezoelectric layer 5 is, for example, 5 ⁇ m or more and 40 ⁇ m or less, preferably 10 ⁇ m or more and 30 ⁇ m or less.
  • the thickness of the piezoelectric layer 5 is, for example, 11 ⁇ m, but is not limited thereto.
  • the material of the piezoelectric layer 5 includes, for example, Pb, Zr, Zn, Nb, and O, but is not limited thereto. More specifically, the material of the piezoelectric layer 5 includes, for example, Pb 1.015 Zr 0.44 (Zn 1/3 Nb 2/3 ) 0.10 O 3.015; The composition ratio is not limited to this.
  • the upper electrode 6 is provided on the upper surface 51 (see FIG. 2) of the piezoelectric layer 5. As shown in FIG. 1, the outer edge 60 of the upper electrode 6 has, for example, a rectangular shape in plan view, but the shape is not limited to this.
  • the thickness of the upper electrode 6 is, for example, 3 ⁇ m, but is not limited thereto.
  • the material of the upper electrode 6 includes, for example, Ag and Pd. More specifically, the material of the upper electrode 6 includes, for example, an Ag--Pd alloy.
  • the outer edge 40 (first outer edge) of the lower electrode 4 is , located inside the outer edge 20 (second outer edge) of the metal substrate 2.
  • the outer edge 50 (third outer edge) of the piezoelectric layer 5 is located inside the outer edge 40 of the lower electrode 4.
  • the outer edge 60 (fourth outer edge) of the upper electrode 6 is located inside the outer edge 50 of the piezoelectric layer 5.
  • the area of the upper surface 41 (see FIG. 2) of the lower electrode 4 is smaller than the area of the upper surface 21 (see FIG.
  • orthogonal coordinates having three axes, the X-axis, Y-axis, and Z-axis that are orthogonal to each other, are defined, and in particular, the axis along the thickness direction of the metal substrate 2 is referred to as the "Z-axis".
  • the axis along the longitudinal direction of the metal substrate 2 is referred to as the "X axis”
  • the axis along the width direction of the metal substrate 2 is referred to as the "Y axis”.
  • the X-axis, Y-axis, and Z-axis are all virtual axes, and the arrows indicating "X,” “Y,” and “Z” in the drawings are only shown for explanation. , none of which involve substance.
  • a part of the portion 411 of the upper surface 41 of the lower electrode 4 that is not covered with the piezoelectric layer 5 also serves as a terminal portion for external connection.
  • the distance between the outer edge 40 of the lower electrode 4 and the outer edge 50 of the piezoelectric layer 5 is not uniform in plan view, and the first width W1 is wider than the second width W2. wide.
  • the first width W1 is the width between the outer edge 40 of the lower electrode 4 and the outer edge 50 of the piezoelectric layer 5 at the first end of the piezoelectric element 1 in the direction along the X axis.
  • the second width W2 is the width between the outer edge 40 of the lower electrode 4 and the outer edge 50 of the piezoelectric layer 5 at the second end of the piezoelectric element 1 in the direction along the X axis.
  • a metal substrate 2A (see FIG. 3) from which a large number of metal substrates 2 can be produced is prepared, and then a first step, a second step, and a third step are performed. , the fourth step, the fifth step, and the sixth step are performed sequentially.
  • the metal substrate 2A containing iron, chromium, and aluminum is heat-treated in the atmosphere to form an alumina layer 3A (see FIG. 3) that covers the entire upper surface 21A of the metal substrate 2A.
  • the heat treatment temperature is, for example, 850° C. or more and 900° C. or less
  • the heat treatment time is, for example, 2 hours.
  • a second alumina layer may be formed that covers the entire lower surface 22A of the metal substrate 2A.
  • a first pattern portion including a plurality of lower electrode material portions is formed on the alumina layer 3A by screen printing a paste containing the material of the lower electrode 4 (eg, Ag-Pd alloy paste).
  • a second pattern section including a plurality of piezoelectric material sections is formed on the first pattern section by printing a paste containing the material of the piezoelectric layer 5 with a metal mask.
  • the material of the piezoelectric layer 5 is, for example, Pb 1.015 Zr 0.44 (Zn 1/3 Nb 2/3 ) 0.10 O 3.015 .
  • a third pattern section including a plurality of upper electrode material sections is formed on the second pattern section by screen printing a paste containing the material of the upper electrode 6 (for example, Ag-Pd alloy paste).
  • a structure 1A including a plurality of piezoelectric elements 1 is formed (see FIG. 3).
  • the structure 1A is separated into individual piezoelectric elements 1 by dicing the structure 1A with a dicing blade 200 (see FIG. 3).
  • the metal substrate 2A and the alumina layer 3A are present in the dicing lane, but the lower electrode pattern section 4A, the piezoelectric layer pattern section 5A, and the upper electrode pattern section 6A are not present.
  • the thickness H2 of the dicing blade 200 is smaller than the first distance L1 between two adjacent lower electrodes 4 across the dicing lane in the structure 1A. Further, the thickness H2 of the dicing blade 200 is smaller than the second distance L2 between two adjacent piezoelectric layers 5 across the dicing lane in the structure 1A.
  • the thickness H2 of the dicing blade 200 is smaller than the third distance L3 between two adjacent upper electrodes 6 across the dicing lane in the structure 1A. As described above, in the sixth step, the relationship of thickness H2 of the dicing blade 200 ⁇ first distance L1 ⁇ second distance L2 ⁇ third distance L3 is satisfied.
  • the method for manufacturing the piezoelectric element 1 cracking and chipping of the lower electrode 4, piezoelectric layer 5, and upper electrode 6 are unlikely to occur in the sixth step. Therefore, according to the method for manufacturing the piezoelectric element 1, it is possible to improve the manufacturing yield. In addition, in the piezoelectric element 1, since it is possible to prevent a handling tool from coming into contact with the lower electrode 4, the piezoelectric layer 5, and the upper electrode 6 during handling, the lower electrode 4, the piezoelectric layer 5, and the upper Damage to the electrode 6 can be prevented. Therefore, in the piezoelectric element 1, the piezoelectric layer 5 can be made thinner than a bulk type piezoelectric element.
  • the structure 1A is diced using the dicing blade 200, but the method is not limited to the method using the dicing blade 200. Dicing may also be performed. In both the method using the dicing blade 200 and laser dicing, the first screen printing mask used in the second step, the first A metal mask used in the third step and a second screen printing mask used in the fourth step are designed.
  • the ultrasonic transducer 100 is configured to be capable of both transmitting (transmitting) ultrasonic waves and receiving (receiving) ultrasonic waves.
  • the ultrasonic transducer 100 is used, for example, as an ultrasonic sensor mounted on a vehicle such as an automobile to detect objects (obstacles, etc.) around the vehicle.
  • the ultrasonic sensor includes, for example, an ultrasonic transducer 100, a drive circuit, and a signal processing circuit.
  • the ultrasonic sensor is, for example, a TOF (Time of Flight) type ultrasonic sensor.
  • the drive circuit applies an electric signal to the piezoelectric element 1 of the ultrasonic transducer 100 to cause the ultrasonic transducer 100 to transmit ultrasonic waves.
  • the signal processing circuit processes an electrical signal output from the piezoelectric element 1 when the ultrasonic transducer 100 receives a reflected wave of an ultrasonic wave.
  • the signal processing circuit detects, for example, at least one of the presence or absence of an object within the detection area of the ultrasonic sensor and the distance from the ultrasonic transducer 100 to the object.
  • the ultrasonic transducer 100 of the ultrasonic sensor is attached to the bumper of an automobile, for example.
  • the ultrasonic transducer 100 has, for example, a vertical direction in the X-axis direction (the left-right direction in FIG. 4) and a vertical direction in the Y-axis direction (the vertical direction in FIG. 4).
  • the ultrasonic transducer 100 is installed so that the direction is horizontal, and the Z-axis direction (direction perpendicular to the plane of the paper in FIG. 4) is the detection direction (transmission/reception direction of ultrasonic waves).
  • the mounting direction of the ultrasonic transducer 100 can be changed as appropriate depending on the use of the ultrasonic transducer 100, for example.
  • the ultrasonic transducer 100 may include at least one of a drive circuit and a signal processing circuit.
  • the case 101 has a cylindrical shape with a bottom. In plan view, the outer edge of the case 101 has a circular shape.
  • the diaphragm section 120 has an upper surface 121 and a lower surface 122, as shown in FIG.
  • the thickness of the diaphragm portion 120 is, for example, 0.3 mm or more and 1.0 mm or less, and is, for example, 0.9 mm.
  • the outer diameter of the case 101 is, for example, 14 mm, but is not limited to this, and may be, for example, 15.5 mm.
  • the length of the case 101 in the Z-axis direction is, for example, 9 mm, but is not limited thereto.
  • the lower surface 122 of the diaphragm portion 120 constitutes an ultrasonic wave transmission/reception surface.
  • the material of the case 101 is, for example, an aluminum alloy, but is not limited thereto, and may be, for example, a magnesium alloy, stainless steel, a titanium alloy, or an engineered plastic.
  • the diaphragm portion 120 has a first maximum length R1 in the first direction (X-axis direction) that is larger than a second maximum length R2 in the second direction (Y-axis direction). It has a long shape. Thereby, in the ultrasonic transducer 100, the directivity angle in the X-axis direction can be narrower than the directivity angle in the Y-axis direction.
  • the first maximum length R1 is 12.6 mm
  • the second maximum length R2 is 8 mm, but is not limited to these values.
  • the joint 105 is interposed between the lower surface 22 of the metal substrate 2 of the piezoelectric element 1 and the upper surface 121 of the diaphragm section 120.
  • the material of the bonding portion 105 is, for example, a resin adhesive, a conductive bonding material, or DAF (Die Attach Film).
  • the resin adhesive includes, for example, an epoxy adhesive.
  • the conductive bonding material includes, for example, conductive paste (silver paste, etc.).
  • first lead wire 141 is connected to the lower electrode 4 of the piezoelectric element 1.
  • the second lead wire 142 constitutes a second conductive member connected to the upper electrode 6 of the piezoelectric element 1 .
  • a first end of the first lead wire 141 is joined to the lower electrode 4 by the first conductive joint 131 and is electrically connected to the lower electrode 4 .
  • a first end of the second lead wire 142 is joined to the upper electrode 6 by the second conductive joint 132 and is electrically connected to the upper electrode 6 .
  • the first lead wire 141 and the second lead wire 142 are flexible electric wires. A portion of the first lead wire 141 and a portion of the second lead wire 142 are led out of the case 101. The second end of the first lead wire 141 and the second end of the second lead wire 142 are connected to, for example, a drive circuit included in the ultrasonic sensor and a signal processing circuit included in the ultrasonic sensor.
  • the material of the first conductive joint 131 and the second conductive joint 132 includes, for example, solder.
  • the ultrasonic transducer 100 when the ultrasonic transducer 100 is used for transmitting ultrasonic waves, the ultrasonic transducer 100 is connected to a drive circuit. Furthermore, in the ultrasonic sensor, when the ultrasonic transducer 100 is used for receiving ultrasonic waves, the ultrasonic transducer 100 is connected to a signal processing circuit.
  • the sound absorbing member 150 is arranged above the piezoelectric element 1 in the case 101.
  • the material of the sound absorbing member 150 includes, for example, foam. Examples of the foam include urethane foam and silicone foam.
  • the sealing section 160 is arranged on the sound absorbing member 150 within the case 101.
  • the material of the sealing part 160 includes, for example, silicone resin.
  • the piezoelectric element 1 according to the first embodiment includes a metal substrate 2 containing iron, chromium, and aluminum.
  • the outer edge 40 (first outer edge) of the lower electrode 4 is located inside the outer edge 20 (second outer edge) of the metal substrate 2
  • the outer edge 50 (third outer edge) is located inside the outer edge 40 of the lower electrode 4
  • the outer edge 60 (fourth outer edge) of the upper electrode 6 is located inside the outer edge 50 (third outer edge) of the piezoelectric layer 5.
  • the piezoelectric element 1 according to the first embodiment it is possible to increase the operating frequency (resonant frequency) of the piezoelectric element 1. More specifically, in the piezoelectric element 1 according to the first embodiment, since the piezoelectric layer 5 can be made thinner, the resonance frequency of the piezoelectric element 1 can be made higher, and the driving frequency can be made higher. becomes possible.
  • the piezoelectric element 1 according to the first embodiment includes an alumina layer 3 interposed between the lower electrode 4 and the metal substrate 2, and the upper surface 31 of the alumina layer 3 has a plurality of scale-like shapes that the alumina layer 3 has. Since the lower electrode 4 includes a part of the surface of the particles, peeling of the lower electrode 4 can be suppressed.
  • the alumina layer 3 covers the entire upper surface 21 of the metal substrate 2, it is possible to improve piezoelectric characteristics. More specifically, in the piezoelectric element 1 according to the first embodiment, it is possible to suppress thermal diffusion between the metal substrate 2 and the piezoelectric layer 5 during manufacturing, and it is possible to improve the piezoelectric characteristics.
  • the ultrasonic transducer 100 includes the piezoelectric element 1 and the diaphragm portion 120 joined to the metal substrate 2 of the piezoelectric element 1. It becomes possible to increase the operating frequency (resonant frequency). Thereby, in the ultrasonic transducer 100, it becomes possible to make the drive frequency of the piezoelectric element 1 higher, and it becomes possible to narrow the directivity angle of the ultrasonic waves. Therefore, for example, when an ultrasonic sensor including the ultrasonic transducer 100 is installed and used in a car, it is possible to suppress the ultrasonic waves transmitted from the ultrasonic transducer 100 from entering the road surface, curb, etc.
  • FIGS. 6 and 7 A piezoelectric element 1a according to the second embodiment will be described with reference to FIGS. 6 and 7, and then an ultrasonic transducer 100a including the piezoelectric element 1a will be described with reference to FIGS. 8 and 9.
  • the same components as those of the piezoelectric element 1 according to the first embodiment are given the same reference numerals, and the description thereof will be omitted.
  • the ultrasonic transducer 100a according to the second embodiment the same components as those in the ultrasonic transducer 100 according to the first embodiment (see FIGS. 4 and 5) are given the same reference numerals, and the description thereof will be omitted as appropriate.
  • the piezoelectric element 1a according to the second embodiment is different from the first embodiment in that it further includes a terminal electrode 7 and a wiring part 8. This is different from the piezoelectric element 1 (see FIGS. 1 and 2).
  • the terminal electrode 7 is provided on the piezoelectric layer 5 and is separated from the upper electrode 6. More specifically, the terminal electrode 7 is provided on the upper surface 51 of the piezoelectric layer 5 and is separated from the upper electrode 6 in the X-axis direction. A gap 9 is formed between the terminal electrode 7 and the upper electrode 6. The portion of the terminal electrode 7 that is connected to the wiring portion 8 is not surrounded by the upper electrode 6 in the X-axis direction, for example.
  • the terminal electrode 7 is arranged on the upper surface 51 of the piezoelectric layer 5 at the first end in the direction along the X-axis.
  • the terminal electrode 7 is located inside the outer edge 50 of the piezoelectric layer 5 in plan view.
  • the terminal electrode 7 has, for example, a square shape, but is not limited to this, and may have a circular shape.
  • the thickness of the terminal electrode 7 is the same as the thickness of the upper electrode 6.
  • the thickness of the terminal electrode 7 is the same as the thickness of the upper electrode 6
  • the thickness of the terminal electrode 7 is 95% of the thickness of the upper electrode 6. This includes cases where the thickness is within a range of 105% or more.
  • the first height from the upper surface 21 of the metal substrate 2 to the upper surface 71 of the terminal electrode 7 is It is the same as the second height from the upper surface 21 to the upper surface 61 of the upper electrode 6.
  • the first height being the same as the second height is not limited to strictly the same case, but the first height is within the range of 95% or more and 105% or less of the second height. Including some cases.
  • the material of the terminal electrode 7 is the same as that of the upper electrode 6, and includes, for example, Ag and Pd.
  • the wiring section 8 is provided across the upper surface 41 of the lower electrode 4, the side surface 53 of the piezoelectric layer 5, and the upper surface 51 of the piezoelectric layer 5, and connects the lower electrode 4 and the terminal electrode 7. Therefore, the wiring section 8 includes a portion 81 formed on the upper surface 51 of the piezoelectric layer 5. The wiring portion 8 is not formed on the lower surface 52 of the piezoelectric layer 5.
  • the material of the wiring part 8 is the same as the material of the upper electrode 6 and the material of the terminal electrode 7, and includes, for example, Ag and Pd.
  • the wiring portion 8 is located inside the outer edge 20 of the metal substrate 2 in plan view.
  • the width of the wiring portion 8 in the Y-axis direction is narrower than the width of the terminal electrode 7 in the Y-axis direction.
  • the wiring portion 8 has an inverted L shape when viewed from the side in the Y-axis direction.
  • the terminal electrode 7 and the wiring portion 8 are formed in the same process as the upper electrode 6 by screen printing.
  • the manufacturing method of the piezoelectric element 1a is almost the same as the manufacturing method of the piezoelectric element 1, and instead of the screen mask used in the fourth step in the manufacturing method of the piezoelectric element 1, an opening for forming the upper electrode 6 and a terminal electrode 7 are used. A screen mask having an opening for forming the wiring portion 8 and an opening for forming the wiring portion 8 is used.
  • the third pattern portion includes a plurality of terminal electrode material portions and a plurality of wiring material portions in addition to the plurality of upper electrode material portions.
  • the lower electrode pattern portion including the plurality of lower electrodes 4 is formed by firing the first pattern portion, the second pattern portion, and the third pattern portion at a predetermined firing temperature (for example, 875° C.).
  • a piezoelectric layer pattern section 5A (see FIG. 3) including a plurality of piezoelectric layers 5, an upper electrode pattern section 6A (see FIG. 3) including a plurality of upper electrodes 6, and a plurality of terminal electrodes 7.
  • a terminal electrode pattern section including a terminal electrode pattern section and a wiring pattern section including a plurality of wiring sections 8 are formed.
  • a structure including a plurality of piezoelectric elements 1a is formed.
  • the ultrasonic transducer 100a according to the second embodiment is different from the embodiment in that the first conductive joint 131a is disposed on the terminal electrode 7. This is different from the ultrasonic transducer 100 according to No. 1 (see FIGS. 4 and 5).
  • the first lead wire 141 and the terminal electrode 7 are joined by the first conductive joint 131a.
  • the material of the first conductive joint 131a includes, for example, solder.
  • the piezoelectric element 1a according to the second embodiment includes a metal substrate 2 containing iron, chromium, and aluminum.
  • the outer edge 40 of the lower electrode 4 is located inside the outer edge 20 of the metal substrate 2
  • the outer edge 50 of the piezoelectric layer 5 is located inside the outer edge 40 of the lower electrode 4.
  • the outer edge 60 of the upper electrode 6 is located inside the outer edge 50 of the piezoelectric layer 5, and the terminal electrode 7 and the wiring portion 8 are located inside the outer edge 20 of the metal substrate 2.
  • the piezoelectric element 1a according to the second embodiment it is possible to increase the operating frequency (resonant frequency) of the piezoelectric element 1a. More specifically, in the piezoelectric element 1a according to the second embodiment, the piezoelectric layer 5 can be made thinner, similar to the piezoelectric element 1 according to the first embodiment, so that the resonant frequency of the piezoelectric element 1a can be made higher. This makes it possible to increase the driving frequency.
  • the piezoelectric element 1a includes the terminal electrode 7 and the wiring part 8, and since the terminal electrode 7 and the wiring part 8 are located inside the outer edge 20 of the metal substrate 2, there is no need to form a folded electrode. Manufacturing becomes easier, and it becomes possible to prevent damage to the terminal electrode 7 and wiring portion 8 during handling of the piezoelectric element 1a.
  • the first height from the upper surface 21 of the metal substrate 2 to the upper surface 71 of the terminal electrode 7 is the same as the second height from the upper surface 21 of the metal substrate 2 to the upper surface 61 of the upper electrode 6.
  • mounting on a flexible printed wiring board including a first lead electrode (first conductor part) and a second lead electrode (second conductor part) becomes easier, and connection reliability can be improved.
  • the first lead electrode (first conductor part) and the second lead electrode (second conductor part) included in the flexible printed wiring board are connected to the first lead wire 141.
  • the second lead wire 142 it is joined to the terminal electrode 7 and the upper electrode 6 of the piezoelectric element 1a by the first conductive joint 131a and the second conductive joint 132.
  • the terminal electrode 7 is located inside the outer edge 50 of the piezoelectric layer 5 in plan view.
  • the wiring portion 8 includes a portion 81 provided on the upper surface 51 of the piezoelectric layer 5 .
  • the terminal electrode 7 connected to the lower electrode 4 is arranged on the upper surface 51 of the piezoelectric layer 5 without adopting the folded electrode structure disclosed in Patent Document 1. It is possible to realize the following configuration.
  • the ultrasonic transducer 100a includes the piezoelectric element 1a and the diaphragm portion 120 joined to the metal substrate 2 of the piezoelectric element 1a. It becomes possible to increase the operating frequency (resonant frequency). Thereby, in the ultrasonic transducer 100a, it becomes possible to increase the driving frequency of the piezoelectric element 1a, and it becomes possible to narrow the directivity angle of the ultrasonic waves. Therefore, for example, when an ultrasonic sensor including the ultrasonic transducer 100a is installed and used in a car, it is possible to suppress the ultrasonic waves transmitted from the ultrasonic transducer 100a from entering the road surface and being reflected. Thereby, it becomes possible to improve the S/N ratio of the ultrasonic sensor, and it becomes possible to further increase the distance at which an object can be detected.
  • the first height from the upper surface 21 of the metal substrate 2 to the upper surface 71 of the terminal electrode 7 in the piezoelectric element 1a is from the upper surface 21 of the metal substrate 2 to the upper surface of the upper electrode 6. It is the same as the second height up to 61.
  • the first lead wire of the flexible printed wiring board is used instead of the first lead wire 141 and the second lead wire 142 as the first conductive member and the second conductive member. (first conductor part) and second lead electrode (second conductor part), mounting on a flexible printed wiring board becomes easy and connection reliability can be improved.
  • FIG. 10 A piezoelectric element 1b according to Embodiment 3 will be described with reference to FIG. 10.
  • the same components as those of the piezoelectric element 1 according to the first embodiment are designated by the same reference numerals, and the description thereof will be omitted as appropriate.
  • the piezoelectric element 1b according to the third embodiment is different from the piezoelectric element 1 according to the first embodiment in that the piezoelectric layer 5 has an opening 54 that exposes a part of the upper surface 41 of the lower electrode 4. do.
  • the opening 54 of the piezoelectric layer 5 is formed along the thickness direction of the piezoelectric layer 5.
  • the opening shape of the opening portion 54 is square, but is not limited to this, and may be circular, for example.
  • a portion of the lower electrode 4 (portion 411b) exposed through the opening 54 of the piezoelectric layer 5 constitutes a terminal portion.
  • the method for manufacturing the piezoelectric element 1b is substantially the same as the method for manufacturing the piezoelectric element 1, and by changing the pattern of the screen mask used in the third step in the method for manufacturing the piezoelectric element 1, the openings 54 of the piezoelectric layer 5 are can be formed.
  • the piezoelectric element 1b according to the third embodiment includes a metal substrate 2 containing iron, chromium, and aluminum.
  • the outer edge 40 of the lower electrode 4 is located inside the outer edge 20 of the metal substrate 2
  • the outer edge 50 of the piezoelectric layer 5 is located inside the outer edge 40 of the lower electrode 4.
  • the outer edge 60 of the upper electrode 6 is located inner than the outer edge 50 of the piezoelectric layer 5 .
  • the piezoelectric layer 5 can be made thinner, similar to the piezoelectric element 1 according to the first embodiment, so that the resonant frequency of the piezoelectric element 1b can be made higher. This makes it possible to increase the driving frequency.
  • the piezoelectric element 1b according to the third embodiment since the piezoelectric layer 5 has an opening 54 that exposes a part of the upper surface 41 of the lower electrode 4, the part of the upper surface 41 of the lower electrode 4 can be used as a terminal part. Can be used for both purposes. As a result, the piezoelectric element 1b according to the third embodiment can have a narrower region functioning as a terminal part than the piezoelectric element 1 according to the first embodiment, and can suppress variations in characteristics during use. It becomes possible.
  • Embodiment 4 An ultrasonic transducer 100c according to Embodiment 4 will be described below with reference to FIG. 12. Regarding the ultrasonic transducer 100c according to the fourth embodiment, the same components as those of the ultrasonic transducer 100 according to the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.
  • the ultrasonic transducer 100c according to the fourth embodiment includes a conical diaphragm section 120c with an open bottom in place of the diaphragm section 120 in the ultrasonic transducer 100 according to the first embodiment.
  • the ultrasonic transducer 100c according to the fourth embodiment includes a case 101c instead of the case 101 in the ultrasonic transducer 100 according to the first embodiment.
  • the piezoelectric element 1 and the diaphragm portion 120c are housed in the case 101c.
  • the diaphragm portion 120c is joined to the lower surface 22 of the metal substrate 2 of the piezoelectric element 1.
  • the diaphragm portion 120c is a separate member from the case 101c and is separated from the case 101c.
  • the case 101c includes a pedestal 170, a cap 106, and a mesh member 165.
  • the ultrasonic transducer 100c also includes a support portion 180 that protrudes from the pedestal 170 and supports the piezoelectric element 1.
  • the ultrasonic transducer 100c also includes a first conductive joint 131 and a second conductive joint 132, a first lead wire 141 and a second lead wire 142, a first lead terminal 191 and a second lead terminal 192. , is provided.
  • the pedestal 170 is disc-shaped.
  • the material of the pedestal 170 is, for example, an aluminum alloy, but is not limited thereto, and may be, for example, a magnesium alloy, stainless steel, a titanium alloy, or an engineered plastic.
  • the cap 106 has a bottomed cylindrical shape having a bottom wall 161 and a cylindrical peripheral wall 162, and is fixed to the pedestal 170 so as to cover the piezoelectric element 1 and the diaphragm portion 120c.
  • the material of the cap 106 is, for example, an aluminum alloy, but is not limited thereto, and may be, for example, a magnesium alloy, stainless steel, a titanium alloy, or an engineered plastic.
  • the mesh member 165 is disposed within a window hole 163 formed in the bottom wall 161 of the cap 106, and is located in front of the diaphragm portion 120c.
  • the mesh member 165 has a plurality of openings 166 to allow ultrasound to pass therethrough.
  • the first lead wire 141 and the second lead wire 142 are flexible electric wires.
  • the first end of the first lead wire 141 is joined and electrically connected to the lower electrode 4 of the piezoelectric element 1 by the first conductive joint 131, and the second end of the first lead wire 141 The end is joined to the first lead terminal 191 and electrically connected.
  • the first end of the second lead wire 142 is joined and electrically connected to the upper electrode 6 of the piezoelectric element 1 by the second conductive joint portion 132. The second end is joined to and electrically connected to the second lead terminal 192.
  • Each of the first lead terminal 191 and the second lead terminal 192 is pin-shaped.
  • the first lead terminal 191 and the second lead terminal 192 penetrate the base 170 in the thickness direction of the base 170.
  • the first lead terminal 191 and the second lead terminal 192 are electrically insulated.
  • the first lead terminal 191 and the second lead terminal 192 are electrically connected to the pedestal 170 by the first insulating part and the second insulating part interposed between the first lead terminal 191 and the second lead terminal 192 and the pedestal 170.
  • it is insulated, it is not limited to this.
  • one of the first lead terminal 191 and the second lead terminal 192 may be electrically connected to the base 170.
  • the ultrasonic transducer 100c includes the piezoelectric element 1 and the diaphragm portion 120c joined to the metal substrate 2 of the piezoelectric element 1, so that the operating frequency (resonant frequency) of the piezoelectric element 1 can be adjusted to a high speed. This makes it possible to achieve Thereby, in the ultrasonic transducer 100c, it becomes possible to increase the driving frequency of the piezoelectric element 1, and it becomes possible to narrow the directivity angle of the ultrasonic waves.
  • Embodiments 1-4 are just one of various embodiments of the present disclosure. Embodiments 1 to 4 can be modified in various ways depending on the design, etc., as long as the objective of the present disclosure can be achieved.
  • the outer edge 20 of the metal substrate 2 in plan view is not limited to a rectangular shape, and may be, for example, square, circular, elliptical, or oval.
  • the metal substrate 2 does not necessarily need to contain aluminum, but only needs to contain at least iron and chromium.
  • the piezoelectric elements 1, 1a, and 1b include the alumina layer 3. That is, the piezoelectric elements 1, 1a, and 1b may not include the alumina layer 3, and the lower electrode 4 may be provided directly on the metal substrate 2.
  • the material of the piezoelectric layer 5 is a material containing Pb, Zr, Zn, Nb, and O, for example, Pb 1.015 Zr 0.44 (Zn 1/3 Nb 2/3 ) 0.10 O 3. 015 , but may be lead zirconate titanate (PZT), barium titanate, lead magnesium niobate (PMN), KNbO 3 , NaNbO 3 or K 0.5 Na 0.5 NbO 3 .
  • the piezoelectric layer 5 is provided directly on the lower electrode 4; however, the piezoelectric layer 5 is not limited to this, and the piezoelectric layer 5 may be provided on the lower electrode 4 via a buffer layer. You can leave it there.
  • the buffer layer includes, for example, at least a portion of the material of the lower electrode 4 and at least a portion of the material of the piezoelectric layer 5.
  • the wiring portion 8 is not limited to the configuration in which it is provided across the upper surface 41 of the lower electrode 4, the side surface 53 of the piezoelectric layer 5, and the upper surface 51 of the piezoelectric layer 5.
  • the wiring portion 8 connects the lower electrode 4 and the terminal electrode 7 and is not provided on the lower surface 52 of the piezoelectric layer 5. It suffices if it is provided astride the side surface 53.
  • the piezoelectric element 1b it is not essential for the piezoelectric element 1b to have a narrow portion between the outer edge 50 of the piezoelectric layer 5 near the opening 54 and the opening 54 of the piezoelectric layer 5; and may be opened laterally.
  • the first conductive member and the second conductive member are not limited to the first lead wire 141 and the second lead wire 142, but are, for example, the first lead included in the conductor pattern portion of the flexible printed wiring board. It may be an electrode (first conductor part) and a second lead electrode (second conductor part).
  • the first conductive member and the second conductive member are not limited to the first lead wire 141 and the second lead wire 142, but are, for example, a first conductive wire and a second conductive wire. Good too.
  • the ultrasonic transducer 100c may include a piezoelectric element 1a or a piezoelectric element 1b instead of the piezoelectric element 1.
  • the piezoelectric element (1; 1a; 1b) includes a metal substrate (2), a lower electrode (4), a piezoelectric layer (5), and an upper electrode (6).
  • the metal substrate (2) contains at least iron and chromium.
  • the lower electrode (4) is provided on the metal substrate (2).
  • the piezoelectric layer (5) is provided on the lower electrode (4).
  • the upper electrode (6) is provided on the piezoelectric layer (5).
  • the first outer edge (outer edge 40) of the lower electrode (4) is located inside the second outer edge (outer edge 20) of the metal substrate 2.
  • the third outer edge (outer edge 50) of the piezoelectric layer (5) is located inside the first outer edge (outer edge 40) of the lower electrode (4).
  • the fourth outer edge (outer edge 60) of the upper electrode (6) is located inside the third outer edge (outer edge 50) of the piezoelectric layer (5).
  • the piezoelectric element (1; 1a; 1b) according to the first aspect, it is possible to increase the operating frequency of the piezoelectric element (1; 1a; 1b).
  • the piezoelectric element (1; 1a; 1b) according to the second embodiment further includes an alumina layer (3) in the first embodiment.
  • the alumina layer (3) is interposed between the metal substrate (2) and the lower electrode (4).
  • the metal substrate (2) further contains aluminum.
  • the upper surface (31) of the alumina layer (3) includes a part of the surface of the plurality of scale-like particles of the alumina layer (3).
  • the piezoelectric element (1; 1a; 1b) according to the second aspect can suppress peeling of the lower electrode (4).
  • the alumina layer (3) covers the entire upper surface (21) of the metal substrate (2).
  • the piezoelectric element (1a) according to the fourth aspect in any one of the first to third aspects, further includes a terminal electrode (7) and a wiring part (8).
  • the terminal electrode (7) is provided on the piezoelectric layer (5) and is separated from the upper electrode (6).
  • the wiring section (8) is provided across the upper surface (41) of the lower electrode (4) and the side surface (53) of the piezoelectric layer (5), and is connected between the lower electrode (4) and the terminal electrode (7). are connected.
  • the wiring portion (8) is located inside the second outer edge (outer edge 20) of the metal substrate (2).
  • the piezoelectric element (1a) according to the fourth aspect can be easily mounted on a flexible printed wiring board and can improve connection reliability.
  • the terminal electrode (7) is located inside the third outer edge (outer edge 50) of the piezoelectric layer (5) in plan view.
  • the wiring portion (8) includes a portion (81) provided on the upper surface (51) of the piezoelectric layer (5).
  • the piezoelectric element (1a) according to the fifth aspect it is possible to improve the uniformity of the thickness of the terminal electrode (7).
  • the piezoelectric layer (5) exposes a part of the upper surface (41) of the lower electrode (4). It has an opening (54).
  • the piezoelectric element (1b) since a part of the upper surface (41) of the lower electrode (4) constitutes the terminal part, it is possible to narrow the area that functions as the terminal part, and when in use This makes it possible to suppress variations in the characteristics of.
  • An ultrasonic transducer (100; 100a; 100c) according to a seventh aspect includes a piezoelectric element (1; 1a; 1b) according to any one of the first to sixth aspects, a diaphragm section (120; 120c), Includes a first conductive member (first lead wire 141), a second conductive member (second lead wire 142), a first conductive joint (131), and a second conductive joint (132). .
  • the diaphragm portion (120; 120c) is joined to the metal substrate (2) of the piezoelectric element (1; 1a; 1b).
  • the first conductive member (first lead wire 141) is connected to the lower electrode (4) of the piezoelectric element (1; 1a; 1b).
  • the second conductive member (second lead wire 142) is connected to the upper electrode (6) of the piezoelectric element (1; 1a; 1b).
  • the first conductive joint (131) joins the lower electrode (4) and the first conductive member (first lead wire 141).
  • the second conductive joint (132) joins the upper electrode (6) and the second conductive member (second lead wire 142).
  • the ultrasonic transducer (100; 100a; 100c) according to the seventh aspect can increase the operating frequency of the piezoelectric element (1; 1a; 1b).
  • the ultrasonic transducer (100; 100a) further includes a case (101) housing the piezoelectric element (1; 1a; 1b) in the seventh aspect.
  • the case (101) has a bottom plate part (102) and a cylindrical part (103).
  • the bottom plate portion (102) has a flat plate shape.
  • the cylindrical portion (103) protrudes from the periphery of one surface of the bottom plate portion (102) in the thickness direction of the bottom plate portion (102), and surrounds the piezoelectric element (1; 1a; 1b).
  • a portion of the bottom plate portion (102) surrounded by the cylinder portion (103) also serves as a diaphragm portion (120).
  • the ultrasonic transducer (100; 100a) according to the eighth aspect can be used, for example, as an ultrasonic sensor that is attached to a vehicle and detects objects outside the vehicle.

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  • Chemical & Material Sciences (AREA)
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  • Transducers For Ultrasonic Waves (AREA)

Abstract

Provided are a piezoelectric element and an ultrasonic transducer with which it is possible to increase the operation frequency of a piezoelectric element. A piezoelectric element (1) comprises a metal substrate (2), a lower electrode (4), a piezoelectric body layer (5), and an upper electrode (6). The metal substrate (2) contains at least iron and chromium. The lower electrode (4) is provided on the metal substrate (2). The piezoelectric body layer (5) is provided on the lower electrode (4). The upper electrode (6) is provided on the piezoelectric body layer (5). In a plan view, a first outer edge of the lower electrode (4) is positioned on the inside of a second outer edge of the metal substrate (2). In the plan view, a third outer edge of the piezoelectric body layer (5) is positioned on the inside of the first outer edge of the lower electrode (4). In the plan view, a fourth outer edge of the upper electrode (6) is positioned on the inside of the third outer edge of the piezoelectric body layer (5).

Description

圧電素子及び超音波トランスデューサPiezoelectric elements and ultrasonic transducers
 本開示は、圧電素子及び超音波トランスデューサに関し、より詳細には、下部電極及び上部電極を有する圧電素子、及び、圧電素子を備える超音波トランスデューサに関する。 The present disclosure relates to a piezoelectric element and an ultrasonic transducer, and more particularly to a piezoelectric element having a lower electrode and an upper electrode, and an ultrasonic transducer including the piezoelectric element.
 特許文献1には、圧電素子を用いた空中用の超音波送受信器として、圧電セラミックと、圧電セラミックの両面に設けられた導電ペーストを焼結してなる銀電極と、有底筒状ケースと、を備える超音波送受信器(超音波トランスデューサ)が開示されている。 Patent Document 1 describes an aerial ultrasonic transmitter/receiver using a piezoelectric element, which includes a piezoelectric ceramic, a silver electrode formed by sintering conductive paste provided on both sides of the piezoelectric ceramic, and a bottomed cylindrical case. An ultrasonic transmitter/receiver (ultrasonic transducer) is disclosed.
 圧電素子では、動作周波数(共振周波数)の高速化が望まれる場合がある。 In piezoelectric elements, there are cases where it is desired to increase the operating frequency (resonant frequency).
特開2014-82655号公報JP2014-82655A
 本開示の目的は、圧電素子の動作周波数の高速化を図ることが可能な圧電素子及び超音波トランスデューサを提供することにある。 An object of the present disclosure is to provide a piezoelectric element and an ultrasonic transducer that can increase the operating frequency of the piezoelectric element.
 本開示の一態様に係る圧電素子は、金属基板と、下部電極と、圧電体層と、上部電極と、を備える。前記金属基板は、少なくとも鉄及びクロムを含む。前記下部電極は、前記金属基板上に設けられている。前記圧電体層は、前記下部電極上に設けられている。前記上部電極は、前記圧電体層上に設けられている。平面視で、前記下部電極の第1外縁は、前記金属基板の第2外縁よりも内側に位置している。前記平面視で、前記圧電体層の第3外縁は、前記下部電極の前記第1外縁よりも内側に位置している。前記平面視で、前記上部電極の第4外縁は、前記圧電体層の前記第3外縁よりも内側に位置している。 A piezoelectric element according to one aspect of the present disclosure includes a metal substrate, a lower electrode, a piezoelectric layer, and an upper electrode. The metal substrate contains at least iron and chromium. The lower electrode is provided on the metal substrate. The piezoelectric layer is provided on the lower electrode. The upper electrode is provided on the piezoelectric layer. In plan view, the first outer edge of the lower electrode is located inside the second outer edge of the metal substrate. In the plan view, the third outer edge of the piezoelectric layer is located inside the first outer edge of the lower electrode. In the plan view, the fourth outer edge of the upper electrode is located inside the third outer edge of the piezoelectric layer.
 本開示の一態様に係る超音波トランスデューサは、前記圧電素子と、振動板部と、第1導通部材と、第2導通部材と、第1導電性接合部と、第2導電性接合部と、を備える。前記振動板部は、前記圧電素子の前記金属基板と接合されている。前記第1導通部材は、前記圧電素子の前記下部電極に接続される。前記第2導通部材は、前記圧電素子の前記上部電極に接続される。前記第1導電性接合部は、前記下部電極と前記第1導通部材とを接合している。前記第2導電性接合部は、前記上部電極と前記第2導通部材とを接合している。 An ultrasonic transducer according to one aspect of the present disclosure includes the piezoelectric element, a diaphragm section, a first conductive member, a second conductive member, a first conductive joint, a second conductive joint, Equipped with. The diaphragm portion is joined to the metal substrate of the piezoelectric element. The first conductive member is connected to the lower electrode of the piezoelectric element. The second conductive member is connected to the upper electrode of the piezoelectric element. The first conductive joint portion joins the lower electrode and the first conductive member. The second conductive joint portion joins the upper electrode and the second conductive member.
図1は、実施形態1に係る圧電素子の平面図である。FIG. 1 is a plan view of a piezoelectric element according to a first embodiment. 図2は、同上の圧電素子に関し、図1のA1-A1線断面図である。FIG. 2 is a sectional view taken along line A1-A1 in FIG. 1 regarding the piezoelectric element same as above. 図3は、同上の圧電素子の製造方法の説明図である。FIG. 3 is an explanatory diagram of a method of manufacturing the same piezoelectric element as above. 図4は、同上の圧電素子を備える超音波トランスデューサの平面図である。FIG. 4 is a plan view of an ultrasonic transducer including the same piezoelectric element as above. 図5は、同上の圧電素子を備える超音波トランスデューサに関し、図4のA2-A2線断面図である。FIG. 5 is a cross-sectional view taken along the line A2-A2 in FIG. 4 regarding an ultrasonic transducer including the piezoelectric element mentioned above. 図6は、実施形態2に係る圧電素子の平面図である。FIG. 6 is a plan view of the piezoelectric element according to the second embodiment. 図7は、同上の圧電素子に関し、図6のA3-A3線断面図である。FIG. 7 is a sectional view taken along line A3-A3 in FIG. 6 regarding the piezoelectric element same as above. 図8は、同上の圧電素子を備える超音波トランスデューサの平面図である。FIG. 8 is a plan view of an ultrasonic transducer including the same piezoelectric element as above. 図9は、同上の圧電素子を備える超音波トランスデューサに関し、図8のA4-A4線断面図である。FIG. 9 is a sectional view taken along the line A4-A4 in FIG. 8 regarding an ultrasonic transducer including the piezoelectric element mentioned above. 図10は、実施形態3に係る圧電素子の平面図である。FIG. 10 is a plan view of a piezoelectric element according to Embodiment 3. 図11は、同上の圧電素子に関し、図10のA5-A5線断面図である。FIG. 11 is a sectional view taken along line A5-A5 in FIG. 10 regarding the piezoelectric element same as above. 図12は、実施形態4に係る超音波トランスデューサの断面図である。FIG. 12 is a sectional view of an ultrasonic transducer according to Embodiment 4.
 以下の実施形態1~4等において参照する各図は、いずれも模式的な図であり、図中の各構成要素の大きさや厚さそれぞれの比が、必ずしも実際の寸法比を反映しているとは限らない。 The drawings referred to in Embodiments 1 to 4 below are all schematic drawings, and the size and thickness ratios of each component in the drawings do not necessarily reflect the actual dimensional ratios. Not necessarily.
 (実施形態1)
 以下、圧電素子1について図1~3に基づいて説明した後、圧電素子1を備える超音波トランスデューサ100について図4及び5に基づいて説明する。
(Embodiment 1)
Hereinafter, the piezoelectric element 1 will be explained based on FIGS. 1 to 3, and then the ultrasonic transducer 100 including the piezoelectric element 1 will be explained based on FIGS. 4 and 5.
 (1)圧電素子及び超音波トランスデューサの概要
 圧電素子1は、図1及び2に示すように、金属基板2と、アルミナ層3と、下部電極4と、圧電体層5と、上部電極6と、を備える。金属基板2は、少なくとも鉄及びクロムを含む。下部電極4は、金属基板2上に設けられている。圧電体層5は、下部電極4上に設けられている。上部電極6は、圧電体層5上に設けられている。平面視で、圧電素子1の外縁は、例えば、四角形状である。「平面視で、」とは、「金属基板2の厚さ方向に沿った方向において金属基板2の上側から見て、」と同じ意味である。言い換えれば、「平面視で、」とは、「金属基板2の厚さ方向からの平面視で、」と同じ意味である。
(1) Outline of piezoelectric element and ultrasonic transducer As shown in FIGS. 1 and 2, the piezoelectric element 1 includes a metal substrate 2, an alumina layer 3, a lower electrode 4, a piezoelectric layer 5, and an upper electrode 6. , is provided. Metal substrate 2 contains at least iron and chromium. The lower electrode 4 is provided on the metal substrate 2. The piezoelectric layer 5 is provided on the lower electrode 4 . The upper electrode 6 is provided on the piezoelectric layer 5. In plan view, the outer edge of the piezoelectric element 1 has, for example, a square shape. "In plan view" has the same meaning as "as seen from above the metal substrate 2 in the direction along the thickness direction of the metal substrate 2." In other words, "in plan view" has the same meaning as "in plan view from the thickness direction of the metal substrate 2."
 超音波トランスデューサ100は、図4及び5に示すように、圧電素子1と、振動板部120と、第1リード線141と、第2リード線142と、第1導電性接合部131と、第2導電性接合部132と、を備える。超音波トランスデューサ100では、第1リード線141が、第1導通部材を構成し、第2リード線142が、第2導通部材を構成している。振動板部120は、圧電素子1の金属基板2と接合されている。より詳細には、振動板部120は、接合部105により、圧電素子1の金属基板2と接合されている。第1リード線141は、圧電素子1の下部電極4に接続される。第2リード線142は、圧電素子1の上部電極6に接続される。第1導電性接合部131は、下部電極4と、第1リード線141と、を接合している。第2導電性接合部132は、上部電極6と、第2リード線142と、を接合している。 As shown in FIGS. 4 and 5, the ultrasonic transducer 100 includes a piezoelectric element 1, a diaphragm section 120, a first lead wire 141, a second lead wire 142, a first conductive joint 131, and a first conductive joint 131. 2 conductive joint portion 132. In the ultrasonic transducer 100, the first lead wire 141 constitutes a first conductive member, and the second lead wire 142 constitutes a second conductive member. The diaphragm section 120 is joined to the metal substrate 2 of the piezoelectric element 1. More specifically, the diaphragm section 120 is joined to the metal substrate 2 of the piezoelectric element 1 by the joining section 105. The first lead wire 141 is connected to the lower electrode 4 of the piezoelectric element 1 . The second lead wire 142 is connected to the upper electrode 6 of the piezoelectric element 1 . The first conductive joint 131 joins the lower electrode 4 and the first lead wire 141. The second conductive joint 132 joins the upper electrode 6 and the second lead wire 142.
 超音波トランスデューサ100は、圧電素子1において第1電気信号(所定の駆動周波数の交流電圧)を第1機械振動に変換することにより、超音波を送波する。超音波トランスデューサ100では、第1電気信号が圧電素子1に印加されたときの圧電素子1の水平方向の伸縮運動による圧電素子1の垂直方向の振動に伴って振動板部120が振動板部120の厚さ方向に振動し、超音波が送波される。また、超音波トランスデューサ100は、例えば、この超音波トランスデューサ100から送波された超音波の反射波が振動板部120に入射したときの振動板部120の厚さ方向の振動に伴う圧電素子1の第2機械振動を、圧電素子1において第2電気信号に変換する。 The ultrasonic transducer 100 transmits ultrasonic waves by converting a first electric signal (AC voltage with a predetermined drive frequency) into a first mechanical vibration in the piezoelectric element 1. In the ultrasonic transducer 100, when the first electric signal is applied to the piezoelectric element 1, the diaphragm part 120 vibrates in the vertical direction due to the horizontal expansion and contraction movement of the piezoelectric element 1. It vibrates in the thickness direction, and ultrasonic waves are transmitted. Further, the ultrasonic transducer 100 includes, for example, a piezoelectric element 1 that accompanies vibration in the thickness direction of the diaphragm section 120 when a reflected wave of an ultrasonic wave transmitted from the ultrasonic transducer 100 is incident on the diaphragm section 120. is converted into a second electrical signal in the piezoelectric element 1.
 超音波トランスデューサ100では、振動板部120は、平板状である。超音波トランスデューサ100は、圧電素子1を収容しているケース101を更に備える。ケース101は、底板部102と、筒部103と、を有する。底板部102は、平板状である。筒部103は、底板部102の一面の周部から底板部102の厚さ方向に突出しており、圧電素子1を囲んでいる。底板部102のうち筒部103により囲まれた部分が、振動板部120を兼ねている。 In the ultrasonic transducer 100, the diaphragm portion 120 has a flat plate shape. The ultrasonic transducer 100 further includes a case 101 housing the piezoelectric element 1. Case 101 has a bottom plate portion 102 and a cylinder portion 103. The bottom plate portion 102 has a flat plate shape. The cylindrical portion 103 protrudes from the periphery of one surface of the bottom plate portion 102 in the thickness direction of the bottom plate portion 102 and surrounds the piezoelectric element 1 . A portion of the bottom plate portion 102 surrounded by the cylindrical portion 103 also serves as a diaphragm portion 120.
 また、超音波トランスデューサ100は、図5に示すように、ケース101内において圧電素子1の上方に配置されている吸音部材150と、ケース101内において吸音部材150上に配置されている封止部160と、を更に備える。なお、図4では、吸音部材150及び封止部160の図示を省略してある。 Further, as shown in FIG. 5, the ultrasonic transducer 100 includes a sound absorbing member 150 disposed above the piezoelectric element 1 in the case 101, and a sealing portion disposed on the sound absorbing member 150 in the case 101. 160. Note that in FIG. 4, illustration of the sound absorbing member 150 and the sealing part 160 is omitted.
 (2)詳細
 (2.1)圧電素子
 以下、実施形態1に係る圧電素子1について、図1及び2を参照して、より詳細に説明する。
(2) Details (2.1) Piezoelectric Element Hereinafter, the piezoelectric element 1 according to the first embodiment will be described in more detail with reference to FIGS. 1 and 2.
 (2.1.1)金属基板
 金属基板2は、平板状である。金属基板2は、図2に示すように、上面(第1主面)21及び下面(第2主面)22を有する。図1に示すように、平面視で、金属基板2の外縁20は、例えば、四角形状(例えば、長方形状)である。金属基板2の厚さは、例えば、0.1mmであるが、これに限らない。
(2.1.1) Metal Substrate The metal substrate 2 has a flat plate shape. The metal substrate 2 has an upper surface (first main surface) 21 and a lower surface (second main surface) 22, as shown in FIG. As shown in FIG. 1, the outer edge 20 of the metal substrate 2 has, for example, a square shape (for example, a rectangular shape) in plan view. The thickness of the metal substrate 2 is, for example, 0.1 mm, but is not limited thereto.
 金属基板2は、鉄とクロムとアルミニウムとを含む。金属基板2は、鉄を主成分として含むステンレス鋼基板であり、鉄の他にクロム及びアルミニウムを含む。金属基板2を構成するステンレス鋼基板は、例えば、アルミニウム含有フェライト系ステンレス鋼基板である。アルミニウム含有フェライト系ステンレス鋼基板は、例えば、クロムの含有量が18wt%であり、アルミニウムの含有量が3wt%である。クロムの含有量は、18wt%に限定されない。また、アルミニウムの含有量は、3wt%に限定されない。金属基板2は、鉄、クロム及びアルミニウム以外の元素を更に含んでいてもよい。 The metal substrate 2 contains iron, chromium, and aluminum. The metal substrate 2 is a stainless steel substrate containing iron as a main component, and contains chromium and aluminum in addition to iron. The stainless steel substrate constituting the metal substrate 2 is, for example, an aluminum-containing ferritic stainless steel substrate. The aluminum-containing ferritic stainless steel substrate has, for example, a chromium content of 18 wt% and an aluminum content of 3 wt%. The content of chromium is not limited to 18 wt%. Further, the aluminum content is not limited to 3 wt%. The metal substrate 2 may further contain elements other than iron, chromium, and aluminum.
 (2.1.2)アルミナ層
 アルミナ層3は、金属基板2の上面21(図2参照)上に設けられている。図1に示すように、平面視で、アルミナ層3の外縁30は、四角形状(例えば、長方形状)である。アルミナ層3の厚さは、例えば、1μmであるが、これに限らない。
(2.1.2) Alumina Layer The alumina layer 3 is provided on the upper surface 21 (see FIG. 2) of the metal substrate 2. As shown in FIG. 1, the outer edge 30 of the alumina layer 3 has a square shape (for example, a rectangular shape) in plan view. The thickness of the alumina layer 3 is, for example, 1 μm, but is not limited thereto.
 アルミナ層3を形成するアルミナの主相は、γ-アルミナ相である。すなわち、アルミナ層3は、主としてγ-アルミナ相の粒子で形成されている。「主としてγ-アルミナ相の粒子で形成されている」とは、アルミナ層3の50重量%を超える部分がγ-アルミナ相の粒子で形成されていることを意味する。アルミナ層3を構成する材料(粒子)の結晶相は、アルミナ層3の露出した部位のX線回折パターンをX線回折装置によって測定することによって同定することができる。アルミナ層3の上面は、アルミナ層3の有する複数の鱗片状の粒子の表面の一部を含んでいる。アルミナ層3の上面のSEM(Scanning Electron Microscope)像及びX線回折パターンの測定結果をあわせて考えると、鱗片状の粒子は、γ-アルミナ粒子であると推定される。 The main phase of alumina forming the alumina layer 3 is a γ-alumina phase. That is, the alumina layer 3 is mainly formed of particles of γ-alumina phase. "Mainly formed of γ-alumina phase particles" means that more than 50% by weight of the alumina layer 3 is formed of γ-alumina phase particles. The crystalline phase of the material (particles) constituting the alumina layer 3 can be identified by measuring the X-ray diffraction pattern of the exposed portion of the alumina layer 3 using an X-ray diffraction device. The upper surface of the alumina layer 3 includes a part of the surface of a plurality of scale-like particles of the alumina layer 3. Considering the SEM (Scanning Electron Microscope) image of the upper surface of the alumina layer 3 and the measurement results of the X-ray diffraction pattern, it is estimated that the scale-like particles are γ-alumina particles.
 (2.1.3)下部電極
 下部電極4は、アルミナ層3の上面31(図2参照)上に設けられている。図1に示すように、平面視で、下部電極4の外縁40は、例えば、四角形状であるが、これに限らない。下部電極4の厚さは、例えば、3μmであるが、これに限らない。
(2.1.3) Lower Electrode The lower electrode 4 is provided on the upper surface 31 (see FIG. 2) of the alumina layer 3. As shown in FIG. 1, the outer edge 40 of the lower electrode 4 has, for example, a rectangular shape in plan view, but the shape is not limited to this. The thickness of the lower electrode 4 is, for example, 3 μm, but is not limited thereto.
 下部電極4の材料は、例えば、銀(Ag)及びパラジウム(Pd)を含む。より詳細には、下部電極4の材料は、例えば、Ag-Pd合金を含む。 The material of the lower electrode 4 includes, for example, silver (Ag) and palladium (Pd). More specifically, the material of the lower electrode 4 includes, for example, an Ag--Pd alloy.
 (2.1.4)圧電体層
 圧電体層5は、下部電極4の上面41(図2参照)上に設けられている。図1に示すように、平面視で、圧電体層5の外縁50は、例えば、四角形状であるが、これに限らない。圧電体層5の厚さは、例えば、5μm以上40μm以下であり、好ましくは、10μm以上30μm以下である。圧電体層5の厚さは、一例として11μmであるが、これに限らない。
(2.1.4) Piezoelectric layer The piezoelectric layer 5 is provided on the upper surface 41 (see FIG. 2) of the lower electrode 4. As shown in FIG. 1, the outer edge 50 of the piezoelectric layer 5 has, for example, a rectangular shape in plan view, but the shape is not limited to this. The thickness of the piezoelectric layer 5 is, for example, 5 μm or more and 40 μm or less, preferably 10 μm or more and 30 μm or less. The thickness of the piezoelectric layer 5 is, for example, 11 μm, but is not limited thereto.
 圧電体層5の材料は、例えば、PbとZrとZnとNbとOとを含むが、これに限らない。より詳細には、圧電体層5の材料は、例えば、Pb1.015Zr0.44(Zn1/3Nb2/30.103.015を含むが、圧電体層5の材料の組成比は、これに限らない。 The material of the piezoelectric layer 5 includes, for example, Pb, Zr, Zn, Nb, and O, but is not limited thereto. More specifically, the material of the piezoelectric layer 5 includes, for example, Pb 1.015 Zr 0.44 (Zn 1/3 Nb 2/3 ) 0.10 O 3.015; The composition ratio is not limited to this.
 (2.1.5)上部電極
 上部電極6は、圧電体層5の上面51(図2参照)上に設けられている。図1に示すように、平面視で、上部電極6の外縁60は、例えば、四角形状であるが、これに限らない。上部電極6の厚さは、例えば、3μmであるが、これに限らない。
(2.1.5) Upper Electrode The upper electrode 6 is provided on the upper surface 51 (see FIG. 2) of the piezoelectric layer 5. As shown in FIG. 1, the outer edge 60 of the upper electrode 6 has, for example, a rectangular shape in plan view, but the shape is not limited to this. The thickness of the upper electrode 6 is, for example, 3 μm, but is not limited thereto.
 上部電極6の材料は、例えば、Ag及びPdを含む。より詳細には、上部電極6の材料は、例えば、Ag-Pd合金を含む。 The material of the upper electrode 6 includes, for example, Ag and Pd. More specifically, the material of the upper electrode 6 includes, for example, an Ag--Pd alloy.
 (2.1.6)圧電素子における、下部電極、圧電体層及び上部電極のレイアウト
 圧電素子1では、図1に示すように、平面視で、下部電極4の外縁40(第1外縁)は、金属基板2の外縁20(第2外縁)よりも内側に位置している。平面視で、圧電体層5の外縁50(第3外縁)は、下部電極4の外縁40よりも内側に位置している。平面視で、上部電極6の外縁60(第4外縁)は、圧電体層5の外縁50よりも内側に位置している。圧電素子1では、下部電極4の上面41(図2参照)の面積が金属基板2の上面21(図2参照)の面積よりも小さく、圧電体層5の上面51(図2参照)の面積が下部電極4の上面41の面積よりも小さく、上部電極6の上面61(図2参照)の面積が圧電体層5の上面51の面積よりも小さい。
(2.1.6) Layout of the lower electrode, piezoelectric layer, and upper electrode in the piezoelectric element In the piezoelectric element 1, as shown in FIG. 1, the outer edge 40 (first outer edge) of the lower electrode 4 is , located inside the outer edge 20 (second outer edge) of the metal substrate 2. In plan view, the outer edge 50 (third outer edge) of the piezoelectric layer 5 is located inside the outer edge 40 of the lower electrode 4. In plan view, the outer edge 60 (fourth outer edge) of the upper electrode 6 is located inside the outer edge 50 of the piezoelectric layer 5. In the piezoelectric element 1, the area of the upper surface 41 (see FIG. 2) of the lower electrode 4 is smaller than the area of the upper surface 21 (see FIG. 2) of the metal substrate 2, and the area of the upper surface 51 (see FIG. 2) of the piezoelectric layer 5 is smaller than the area of the upper surface 41 of the lower electrode 4, and the area of the upper surface 61 (see FIG. 2) of the upper electrode 6 is smaller than the area of the upper surface 51 of the piezoelectric layer 5.
 以下では、図1に示すように、互いに直交するX軸、Y軸及びZ軸の3軸を有する直交座標を規定し、特に、金属基板2の厚さ方向に沿った軸を「Z軸」とし、金属基板2の長手方向に沿った軸を「X軸」とし、金属基板2の短手方向に沿った軸を「Y軸」として説明する。X軸、Y軸、及びZ軸は、いずれも仮想的な軸であり、図面中の「X」、「Y」、「Z」を示す矢印は、説明のために表記しているに過ぎず、いずれも実体を伴わない。 In the following, as shown in FIG. 1, orthogonal coordinates having three axes, the X-axis, Y-axis, and Z-axis that are orthogonal to each other, are defined, and in particular, the axis along the thickness direction of the metal substrate 2 is referred to as the "Z-axis". In the following description, the axis along the longitudinal direction of the metal substrate 2 is referred to as the "X axis", and the axis along the width direction of the metal substrate 2 is referred to as the "Y axis". The X-axis, Y-axis, and Z-axis are all virtual axes, and the arrows indicating "X," "Y," and "Z" in the drawings are only shown for explanation. , none of which involve substance.
 圧電素子1では、下部電極4の上面41のうち圧電体層5に覆われていない部位411の一部が、外部接続用の端子部を兼ねている。圧電素子1では、図1に示すように、平面視で、下部電極4の外縁40と圧電体層5の外縁50との距離が一様ではなく、第1幅W1が第2幅W2よりも広い。第1幅W1は、X軸に沿った方向の圧電素子1の第1端における、下部電極4の外縁40と圧電体層5の外縁50との間の幅である。第2幅W2は、X軸に沿った方向の圧電素子1の第2端における、下部電極4の外縁40と圧電体層5の外縁50との間の幅である。 In the piezoelectric element 1, a part of the portion 411 of the upper surface 41 of the lower electrode 4 that is not covered with the piezoelectric layer 5 also serves as a terminal portion for external connection. In the piezoelectric element 1, as shown in FIG. 1, the distance between the outer edge 40 of the lower electrode 4 and the outer edge 50 of the piezoelectric layer 5 is not uniform in plan view, and the first width W1 is wider than the second width W2. wide. The first width W1 is the width between the outer edge 40 of the lower electrode 4 and the outer edge 50 of the piezoelectric layer 5 at the first end of the piezoelectric element 1 in the direction along the X axis. The second width W2 is the width between the outer edge 40 of the lower electrode 4 and the outer edge 50 of the piezoelectric layer 5 at the second end of the piezoelectric element 1 in the direction along the X axis.
 (2.1.7)圧電素子の製造方法
 実施形態1に係る圧電素子1の製造方法について、図3を参照しながら簡単に説明する。
(2.1.7) Method for manufacturing piezoelectric element A method for manufacturing piezoelectric element 1 according to Embodiment 1 will be briefly described with reference to FIG. 3.
 実施形態1に係る圧電素子1の製造方法では、まず、金属基板2の多数個取りが可能な金属基板2A(図3参照)を準備し、その後、第1工程、第2工程、第3工程、第4工程、第5工程及び第6工程を順次行う。 In the method for manufacturing the piezoelectric element 1 according to the first embodiment, first, a metal substrate 2A (see FIG. 3) from which a large number of metal substrates 2 can be produced is prepared, and then a first step, a second step, and a third step are performed. , the fourth step, the fifth step, and the sixth step are performed sequentially.
 第1工程では、鉄とクロムとアルミニウムとを含む金属基板2Aを大気中で加熱処理することにより、金属基板2Aの上面21Aの全域を覆うアルミナ層3A(図3参照)を形成する。加熱処理の条件に関し、熱処理温度は、例えば、850℃以上900℃以下であり、熱処理時間は、例えば、2時間である。なお、第1工程では、アルミナ層3Aである第1アルミナ層3Aの他に、金属基板2Aの下面22Aの全域を覆う第2アルミナ層が形成されてもよい。 In the first step, the metal substrate 2A containing iron, chromium, and aluminum is heat-treated in the atmosphere to form an alumina layer 3A (see FIG. 3) that covers the entire upper surface 21A of the metal substrate 2A. Regarding the conditions of the heat treatment, the heat treatment temperature is, for example, 850° C. or more and 900° C. or less, and the heat treatment time is, for example, 2 hours. Note that in the first step, in addition to the first alumina layer 3A, which is the alumina layer 3A, a second alumina layer may be formed that covers the entire lower surface 22A of the metal substrate 2A.
 第2工程では、下部電極4の材料を含むペースト(例えば、Ag-Pd合金ペースト)をスクリーン印刷することによって、複数の下部電極材料部を含む第1パターン部をアルミナ層3A上に形成する。 In the second step, a first pattern portion including a plurality of lower electrode material portions is formed on the alumina layer 3A by screen printing a paste containing the material of the lower electrode 4 (eg, Ag-Pd alloy paste).
 第3工程では、圧電体層5の材料を含むペーストをメタルマスク印刷することによって、複数の圧電体材料部を含む第2パターン部を第1パターン部上に形成する。圧電体層5の材料は、例えば、Pb1.015Zr0.44(Zn1/3Nb2/30.103.015である。 In the third step, a second pattern section including a plurality of piezoelectric material sections is formed on the first pattern section by printing a paste containing the material of the piezoelectric layer 5 with a metal mask. The material of the piezoelectric layer 5 is, for example, Pb 1.015 Zr 0.44 (Zn 1/3 Nb 2/3 ) 0.10 O 3.015 .
 第4工程では、上部電極6の材料を含むペースト(例えば、Ag-Pd合金ペースト)をスクリーン印刷することによって、第2パターン部上に複数の上部電極材料部を含む第3パターン部を形成する。 In the fourth step, a third pattern section including a plurality of upper electrode material sections is formed on the second pattern section by screen printing a paste containing the material of the upper electrode 6 (for example, Ag-Pd alloy paste). .
 第5工程では、第1パターン部、第2パターン部及び第3パターン部を所定の焼成温度(例えば、875℃)で焼成することによって、複数の下部電極4を含む下部電極パターン部4A、複数の圧電体層5を含む圧電体層パターン部5A及び複数の上部電極6を含む上部電極パターン部6Aを形成する(図3参照)。これにより、複数の圧電素子1を含む構造体1Aが形成される(図3参照)。 In the fifth step, by firing the first pattern part, the second pattern part, and the third pattern part at a predetermined firing temperature (e.g., 875° C.), the lower electrode pattern part 4A including the plurality of lower electrodes 4, the plurality of lower electrode pattern parts 4A, A piezoelectric layer pattern section 5A including a piezoelectric layer 5 and an upper electrode pattern section 6A including a plurality of upper electrodes 6 are formed (see FIG. 3). As a result, a structure 1A including a plurality of piezoelectric elements 1 is formed (see FIG. 3).
 第6工程では、ダイシングブレード200(図3参照)により構造体1Aをダイシングすることによって、構造体1Aを個々の圧電素子1に分離する。構造体1Aにおいてダイシングレーンには、金属基板2A及びアルミナ層3Aは存在するが、下部電極パターン部4A、圧電体層パターン部5A及び上部電極パターン部6Aは存在しない。ここで、ダイシングブレード200の厚みH2は、構造体1Aにおいてダイシングレーンを挟んで隣り合う2つの下部電極4間の第1距離L1よりも小さい。また、ダイシングブレード200の厚みH2は、構造体1Aにおいてダイシングレーンを挟んで隣り合う2つの圧電体層5間の第2距離L2よりも小さい。また、ダイシングブレード200の厚みH2は、構造体1Aにおいてダイシングレーンを挟んで隣り合う2つの上部電極6間の第3距離L3よりも小さい。以上より、第6工程では、ダイシングブレード200の厚みH2<第1距離L1<第2距離L2<第3距離L3、の関係を満たす。 In the sixth step, the structure 1A is separated into individual piezoelectric elements 1 by dicing the structure 1A with a dicing blade 200 (see FIG. 3). In the structure 1A, the metal substrate 2A and the alumina layer 3A are present in the dicing lane, but the lower electrode pattern section 4A, the piezoelectric layer pattern section 5A, and the upper electrode pattern section 6A are not present. Here, the thickness H2 of the dicing blade 200 is smaller than the first distance L1 between two adjacent lower electrodes 4 across the dicing lane in the structure 1A. Further, the thickness H2 of the dicing blade 200 is smaller than the second distance L2 between two adjacent piezoelectric layers 5 across the dicing lane in the structure 1A. Further, the thickness H2 of the dicing blade 200 is smaller than the third distance L3 between two adjacent upper electrodes 6 across the dicing lane in the structure 1A. As described above, in the sixth step, the relationship of thickness H2 of the dicing blade 200<first distance L1<second distance L2<third distance L3 is satisfied.
 圧電素子1の製造方法によれば、第6工程において、下部電極4、圧電体層5及び上部電極6の割れ及び欠け(チッピング)が発生し難い。したがって、圧電素子1の製造方法によれば、製造歩留まりの向上を図れる。また、圧電素子1では、ハンドリングする際にハンドリング用のツールが下部電極4、圧電体層5及び上部電極6に接触するのを防止することができるので、下部電極4、圧電体層5及び上部電極6の破損を防止することができる。よって、圧電素子1は、バルク型の圧電素子と比べて、圧電体層5の薄型化が可能である。 According to the method for manufacturing the piezoelectric element 1, cracking and chipping of the lower electrode 4, piezoelectric layer 5, and upper electrode 6 are unlikely to occur in the sixth step. Therefore, according to the method for manufacturing the piezoelectric element 1, it is possible to improve the manufacturing yield. In addition, in the piezoelectric element 1, since it is possible to prevent a handling tool from coming into contact with the lower electrode 4, the piezoelectric layer 5, and the upper electrode 6 during handling, the lower electrode 4, the piezoelectric layer 5, and the upper Damage to the electrode 6 can be prevented. Therefore, in the piezoelectric element 1, the piezoelectric layer 5 can be made thinner than a bulk type piezoelectric element.
 なお、第6工程では、ダイシングブレード200により構造体1Aをダイシングしているが、ダイシングブレード200を用いた方法に限らず、構造体1Aのダイシングレーンに沿ってレーザ光を照射してダイシングするレーザダイシングを行ってもよい。ダイシングブレード200を用いた方法、レーザダイシングのいずれの場合も、ダイシングレーンの幅寸法がダイシングによる切削幅(最大幅)よりも広くなるように、第2工程で用いる第1スクリーン印刷用マスク、第3工程で用いるメタルマスク及び第4工程で用いる第2スクリーン印刷用マスクを設計してある。 Note that in the sixth step, the structure 1A is diced using the dicing blade 200, but the method is not limited to the method using the dicing blade 200. Dicing may also be performed. In both the method using the dicing blade 200 and laser dicing, the first screen printing mask used in the second step, the first A metal mask used in the third step and a second screen printing mask used in the fourth step are designed.
 (2.2)超音波トランスデューサ
 以下、実施形態1に係る超音波トランスデューサ100について、図4及び5を参照して、より詳細に説明する。
(2.2) Ultrasonic Transducer The ultrasonic transducer 100 according to the first embodiment will be described in more detail below with reference to FIGS. 4 and 5.
 超音波トランスデューサ100は、超音波の送波(送信)と超音波の受波(受信)との両方が可能に構成されている。超音波トランスデューサ100は、例えば、自動車等の車両に搭載されて車両の周囲の物体(障害物等)を検知する超音波センサに用いられる。超音波センサは、例えば、超音波トランスデューサ100と、駆動回路と、信号処理回路と、を備える。超音波センサは、例えば、TOF(Time of Flight)型の超音波センサである。駆動回路は、超音波トランスデューサ100から超音波を送波させるために超音波トランスデューサ100の圧電素子1を駆動する電気信号を圧電素子1へ印加する。信号処理回路は、超音波トランスデューサ100が超音波の反射波を受波したときに圧電素子1から出力される電気信号を処理する。信号処理回路は、例えば、超音波センサの検知エリア内の物体の有無と、超音波トランスデューサ100から物体までの距離と、の少なくとも一方を検知する。超音波センサの超音波トランスデューサ100は、例えば、自動車のバンパーに取り付けられる。超音波トランスデューサ100を自動車用の超音波センサとして用いる場合、超音波トランスデューサ100は、例えば、X軸方向(図4での左右方向)が垂直方向となり、Y軸方向(図4での上下方向)が水平方向となり、Z軸方向(図4での紙面に直交する方向)が検知方向(超音波の送受波方向)となるように設置される。なお、超音波トランスデューサ100の取り付けの向きは、例えば、超音波トランスデューサ100の用途に応じて適宜変更可能である。なお、超音波トランスデューサ100が駆動回路及び信号処理回路の少なくとも一方を含んでいてもよい。 The ultrasonic transducer 100 is configured to be capable of both transmitting (transmitting) ultrasonic waves and receiving (receiving) ultrasonic waves. The ultrasonic transducer 100 is used, for example, as an ultrasonic sensor mounted on a vehicle such as an automobile to detect objects (obstacles, etc.) around the vehicle. The ultrasonic sensor includes, for example, an ultrasonic transducer 100, a drive circuit, and a signal processing circuit. The ultrasonic sensor is, for example, a TOF (Time of Flight) type ultrasonic sensor. The drive circuit applies an electric signal to the piezoelectric element 1 of the ultrasonic transducer 100 to cause the ultrasonic transducer 100 to transmit ultrasonic waves. The signal processing circuit processes an electrical signal output from the piezoelectric element 1 when the ultrasonic transducer 100 receives a reflected wave of an ultrasonic wave. The signal processing circuit detects, for example, at least one of the presence or absence of an object within the detection area of the ultrasonic sensor and the distance from the ultrasonic transducer 100 to the object. The ultrasonic transducer 100 of the ultrasonic sensor is attached to the bumper of an automobile, for example. When the ultrasonic transducer 100 is used as an ultrasonic sensor for an automobile, the ultrasonic transducer 100 has, for example, a vertical direction in the X-axis direction (the left-right direction in FIG. 4) and a vertical direction in the Y-axis direction (the vertical direction in FIG. 4). is installed so that the direction is horizontal, and the Z-axis direction (direction perpendicular to the plane of the paper in FIG. 4) is the detection direction (transmission/reception direction of ultrasonic waves). Note that the mounting direction of the ultrasonic transducer 100 can be changed as appropriate depending on the use of the ultrasonic transducer 100, for example. Note that the ultrasonic transducer 100 may include at least one of a drive circuit and a signal processing circuit.
 (2.2.1)ケース
 ケース101では、底板部102と筒部103とが一体に形成されている。ケース101の形状は、有底筒状である。平面視で、ケース101の外縁は、円形状である。振動板部120は、図5に示すように、上面121及び下面122を有する。振動板部120の厚さは、例えば、0.3mm以上1.0mm以下であり、一例として、0.9mmである。平面視で、ケース101の外径は、例えば、14mmであるが、これに限らず、例えば、15.5mmでもよい。また、Z軸方向におけるケース101の長さは、例えば、9mmであるが、これに限らない。ケース101では、振動板部120の下面122が超音波の送受波面を構成している。
(2.2.1) Case In the case 101, the bottom plate portion 102 and the cylindrical portion 103 are integrally formed. The case 101 has a cylindrical shape with a bottom. In plan view, the outer edge of the case 101 has a circular shape. The diaphragm section 120 has an upper surface 121 and a lower surface 122, as shown in FIG. The thickness of the diaphragm portion 120 is, for example, 0.3 mm or more and 1.0 mm or less, and is, for example, 0.9 mm. In plan view, the outer diameter of the case 101 is, for example, 14 mm, but is not limited to this, and may be, for example, 15.5 mm. Further, the length of the case 101 in the Z-axis direction is, for example, 9 mm, but is not limited thereto. In the case 101, the lower surface 122 of the diaphragm portion 120 constitutes an ultrasonic wave transmission/reception surface.
 ケース101の材料は、例えば、アルミニウム合金であるが、これに限らず、例えば、マグネシウム合金、ステンレス鋼、チタン合金又はエンジニアプラスチックでもよい。 The material of the case 101 is, for example, an aluminum alloy, but is not limited thereto, and may be, for example, a magnesium alloy, stainless steel, a titanium alloy, or an engineered plastic.
 図4に示すように、平面視で、振動板部120は、第1方向(X軸方向)における第1最大長さR1が第2方向(Y軸方向)における第2最大長さR2に比べて長くなる形状である。これにより、超音波トランスデューサ100では、X軸方向の指向角をY軸方向の指向角よりも狭くできる。なお、第1最大長さR1は、12.6mm、第2最大長さR2は、8mmであるが、これらの数値に限定されない。 As shown in FIG. 4, in plan view, the diaphragm portion 120 has a first maximum length R1 in the first direction (X-axis direction) that is larger than a second maximum length R2 in the second direction (Y-axis direction). It has a long shape. Thereby, in the ultrasonic transducer 100, the directivity angle in the X-axis direction can be narrower than the directivity angle in the Y-axis direction. Note that the first maximum length R1 is 12.6 mm, and the second maximum length R2 is 8 mm, but is not limited to these values.
 (2.2.2)接合部
 図5に示すように、接合部105は、圧電素子1の金属基板2の下面22と振動板部120の上面121との間に介在している。接合部105の材料は、例えば、樹脂系接着剤、導電性接合材料又はDAF(Die Attach Film)である。樹脂系接着剤は、例えば、エポキシ接着剤を含む。導電性接合材料は、例えば、導電性ペースト(銀ペースト等)を含む。
(2.2.2) Joint As shown in FIG. 5, the joint 105 is interposed between the lower surface 22 of the metal substrate 2 of the piezoelectric element 1 and the upper surface 121 of the diaphragm section 120. The material of the bonding portion 105 is, for example, a resin adhesive, a conductive bonding material, or DAF (Die Attach Film). The resin adhesive includes, for example, an epoxy adhesive. The conductive bonding material includes, for example, conductive paste (silver paste, etc.).
 (2.2.3)第1リード線、第2リード線、第1導電性接合部、第2導電性接合部
 超音波トランスデューサ100では、第1リード線141が、圧電素子1の下部電極4に接続される第1導通部材を構成し、第2リード線142が、圧電素子1の上部電極6に接続される第2導通部材を構成している。第1リード線141の第1端は、第1導電性接合部131によって下部電極4に接合されて下部電極4と電気的に接続されている。第2リード線142の第1端は、第2導電性接合部132によって上部電極6に接合されて上部電極6と電気的に接続されている。
(2.2.3) First lead wire, second lead wire, first conductive joint, second conductive joint In the ultrasonic transducer 100, the first lead wire 141 is connected to the lower electrode 4 of the piezoelectric element 1. The second lead wire 142 constitutes a second conductive member connected to the upper electrode 6 of the piezoelectric element 1 . A first end of the first lead wire 141 is joined to the lower electrode 4 by the first conductive joint 131 and is electrically connected to the lower electrode 4 . A first end of the second lead wire 142 is joined to the upper electrode 6 by the second conductive joint 132 and is electrically connected to the upper electrode 6 .
 第1リード線141及び第2リード線142は、可撓性を有する電線である。第1リード線141の一部及び第2リード線142の一部は、ケース101の外に導出されている。第1リード線141の第2端及び第2リード線142の第2端は、例えば、超音波センサの備える駆動回路と超音波センサの備える信号処理回路とに接続される。 The first lead wire 141 and the second lead wire 142 are flexible electric wires. A portion of the first lead wire 141 and a portion of the second lead wire 142 are led out of the case 101. The second end of the first lead wire 141 and the second end of the second lead wire 142 are connected to, for example, a drive circuit included in the ultrasonic sensor and a signal processing circuit included in the ultrasonic sensor.
 第1導電性接合部131及び第2導電性接合部132の材料は、例えば、はんだを含む。 The material of the first conductive joint 131 and the second conductive joint 132 includes, for example, solder.
 なお、超音波センサでは、超音波トランスデューサ100を超音波の送波(送信)に用いる場合には、超音波トランスデューサ100が駆動回路に接続される。また、超音波センサでは、超音波トランスデューサ100を超音波の受波(受信)に用いる場合には、超音波トランスデューサ100が信号処理回路に接続される。 Note that in the ultrasonic sensor, when the ultrasonic transducer 100 is used for transmitting ultrasonic waves, the ultrasonic transducer 100 is connected to a drive circuit. Furthermore, in the ultrasonic sensor, when the ultrasonic transducer 100 is used for receiving ultrasonic waves, the ultrasonic transducer 100 is connected to a signal processing circuit.
 (2.2.4)吸音部材
 吸音部材150は、ケース101内において圧電素子1の上方に配置されている。吸音部材150の材料は、例えば、発泡体を含む。発泡体は、例えば、ウレタン系の発泡体、発泡シリコーンを含む。
(2.2.4) Sound Absorbing Member The sound absorbing member 150 is arranged above the piezoelectric element 1 in the case 101. The material of the sound absorbing member 150 includes, for example, foam. Examples of the foam include urethane foam and silicone foam.
 (2.2.5)封止部
 封止部160は、ケース101内において吸音部材150上に配置されている。封止部160の材料は、例えば、シリコーン樹脂を含む。
(2.2.5) Sealing Section The sealing section 160 is arranged on the sound absorbing member 150 within the case 101. The material of the sealing part 160 includes, for example, silicone resin.
 (3)効果
 (3.1)圧電素子
 実施形態1に係る圧電素子1は、鉄とクロムとアルミニウムとを含む金属基板2を備える。実施形態1に係る圧電素子1では、平面視で、下部電極4の外縁40(第1外縁)が、金属基板2の外縁20(第2外縁)よりも内側に位置し、圧電体層5の外縁50(第3外縁)が、下部電極4の外縁40よりも内側に位置し、上部電極6の外縁60(第4外縁)が、圧電体層5の外縁50(第3外縁)よりも内側に位置している。これにより、実施形態1に係る圧電素子1によれば、圧電素子1の動作周波数(共振周波数)の高速化を図ることが可能となる。より詳細には、実施形態1に係る圧電素子1は、圧電体層5の薄型化を図ることができるので、圧電素子1の共振周波数をより高くすることが可能となり、駆動周波数をより高くすることが可能となる。
(3) Effects (3.1) Piezoelectric Element The piezoelectric element 1 according to the first embodiment includes a metal substrate 2 containing iron, chromium, and aluminum. In the piezoelectric element 1 according to the first embodiment, in plan view, the outer edge 40 (first outer edge) of the lower electrode 4 is located inside the outer edge 20 (second outer edge) of the metal substrate 2, and The outer edge 50 (third outer edge) is located inside the outer edge 40 of the lower electrode 4, and the outer edge 60 (fourth outer edge) of the upper electrode 6 is located inside the outer edge 50 (third outer edge) of the piezoelectric layer 5. It is located in Thereby, according to the piezoelectric element 1 according to the first embodiment, it is possible to increase the operating frequency (resonant frequency) of the piezoelectric element 1. More specifically, in the piezoelectric element 1 according to the first embodiment, since the piezoelectric layer 5 can be made thinner, the resonance frequency of the piezoelectric element 1 can be made higher, and the driving frequency can be made higher. becomes possible.
 また、実施形態1に係る圧電素子1は、下部電極4と金属基板2との間に介在しているアルミナ層3を備え、アルミナ層3の上面31が、アルミナ層3の有する複数の鱗片状の粒子の表面の一部を含むので、下部電極4の剥離を抑制することが可能となる。 Furthermore, the piezoelectric element 1 according to the first embodiment includes an alumina layer 3 interposed between the lower electrode 4 and the metal substrate 2, and the upper surface 31 of the alumina layer 3 has a plurality of scale-like shapes that the alumina layer 3 has. Since the lower electrode 4 includes a part of the surface of the particles, peeling of the lower electrode 4 can be suppressed.
 実施形態1に係る圧電素子1では、アルミナ層3が金属基板2の上面21の全域を覆っているので、圧電特性を向上させることが可能となる。より詳細には、実施形態1に係る圧電素子1では、製造時において金属基板2と圧電体層5との間で熱拡散が起こることを抑制でき、圧電特性を向上させることが可能となる。 In the piezoelectric element 1 according to the first embodiment, since the alumina layer 3 covers the entire upper surface 21 of the metal substrate 2, it is possible to improve piezoelectric characteristics. More specifically, in the piezoelectric element 1 according to the first embodiment, it is possible to suppress thermal diffusion between the metal substrate 2 and the piezoelectric layer 5 during manufacturing, and it is possible to improve the piezoelectric characteristics.
 (3.2)超音波トランスデューサ
 実施形態1に係る超音波トランスデューサ100は、圧電素子1と、圧電素子1の金属基板2と接合されている振動板部120と、を備えるので、圧電素子1の動作周波数(共振周波数)の高速化を図ることが可能となる。これにより、超音波トランスデューサ100では、圧電素子1の駆動周波数をより高くすることが可能となり、超音波の指向角の挟角化を図ることが可能となる。よって、例えば、超音波トランスデューサ100を備える超音波センサを自動車に設置して用いる場合に、超音波トランスデューサ100から送波された超音波が路面、縁石等に入射することを抑制でき、路面、縁石等からの反射波が超音波トランスデューサ100で受波されることを抑制できる。これにより、超音波センサのS/N比を向上させることが可能となり、検知対象の物体を検知可能な距離をより長くすることが可能となる。
(3.2) Ultrasonic transducer The ultrasonic transducer 100 according to the first embodiment includes the piezoelectric element 1 and the diaphragm portion 120 joined to the metal substrate 2 of the piezoelectric element 1. It becomes possible to increase the operating frequency (resonant frequency). Thereby, in the ultrasonic transducer 100, it becomes possible to make the drive frequency of the piezoelectric element 1 higher, and it becomes possible to narrow the directivity angle of the ultrasonic waves. Therefore, for example, when an ultrasonic sensor including the ultrasonic transducer 100 is installed and used in a car, it is possible to suppress the ultrasonic waves transmitted from the ultrasonic transducer 100 from entering the road surface, curb, etc. It is possible to suppress reflected waves from the ultrasonic transducer 100 from being received by the ultrasonic transducer 100. Thereby, it becomes possible to improve the S/N ratio of the ultrasonic sensor, and it becomes possible to further increase the distance at which the object to be detected can be detected.
 (実施形態2)
 実施形態2に係る圧電素子1aについて、図6及び7を参照して説明し、その後、圧電素子1aを備える超音波トランスデューサ100aについて、図8及び9を参照して説明する。実施形態2に係る圧電素子1aに関し、実施形態1に係る圧電素子1(図1及び2参照)と同様の構成要素については、同一の符号を付して説明を省略する。また、実施形態2に係る超音波トランスデューサ100aに関し、実施形態1に係る超音波トランスデューサ100(図4及び5参照)と同様の構成要素については、同一の符号を付して説明を適宜省略する。
(Embodiment 2)
A piezoelectric element 1a according to the second embodiment will be described with reference to FIGS. 6 and 7, and then an ultrasonic transducer 100a including the piezoelectric element 1a will be described with reference to FIGS. 8 and 9. Regarding the piezoelectric element 1a according to the second embodiment, the same components as those of the piezoelectric element 1 according to the first embodiment (see FIGS. 1 and 2) are given the same reference numerals, and the description thereof will be omitted. Further, regarding the ultrasonic transducer 100a according to the second embodiment, the same components as those in the ultrasonic transducer 100 according to the first embodiment (see FIGS. 4 and 5) are given the same reference numerals, and the description thereof will be omitted as appropriate.
 (1)構成
 (1.1)圧電素子
 実施形態2に係る圧電素子1aは、図6及び7に示すように、端子電極7と、配線部8と、を更に備える点で、実施形態1に係る圧電素子1(図1及び2参照)と相違する。
(1) Configuration (1.1) Piezoelectric element As shown in FIGS. 6 and 7, the piezoelectric element 1a according to the second embodiment is different from the first embodiment in that it further includes a terminal electrode 7 and a wiring part 8. This is different from the piezoelectric element 1 (see FIGS. 1 and 2).
 端子電極7は、圧電体層5上に設けられており、上部電極6から離れている。より詳細には、端子電極7は、圧電体層5の上面51上に設けられており、X軸方向において上部電極6から離れている。端子電極7と上部電極6との間には空隙9が形成されている。端子電極7のうち配線部8につながっている部位は、例えば、X軸方向において上部電極6に囲まれていない。圧電素子1aでは、端子電極7は、圧電体層5の上面51において、X軸に沿った方向の第1端に、配置されている。ここで、平面視で、端子電極7は、圧電体層5の外縁50よりも内側に位置している。平面視で、端子電極7は、例えば、四角形状であるが、これに限らず、円形状であってもよい。 The terminal electrode 7 is provided on the piezoelectric layer 5 and is separated from the upper electrode 6. More specifically, the terminal electrode 7 is provided on the upper surface 51 of the piezoelectric layer 5 and is separated from the upper electrode 6 in the X-axis direction. A gap 9 is formed between the terminal electrode 7 and the upper electrode 6. The portion of the terminal electrode 7 that is connected to the wiring portion 8 is not surrounded by the upper electrode 6 in the X-axis direction, for example. In the piezoelectric element 1a, the terminal electrode 7 is arranged on the upper surface 51 of the piezoelectric layer 5 at the first end in the direction along the X-axis. Here, the terminal electrode 7 is located inside the outer edge 50 of the piezoelectric layer 5 in plan view. In plan view, the terminal electrode 7 has, for example, a square shape, but is not limited to this, and may have a circular shape.
 端子電極7の厚さは、上部電極6の厚さと同じである。ここにおいて、「端子電極7の厚さは、上部電極6の厚さと同じ」とは、厳密に同じ場合のみに限定されず、端子電極7の厚さが、上部電極6の厚さの95%以上105%以下の範囲内の厚さである場合を含む。 The thickness of the terminal electrode 7 is the same as the thickness of the upper electrode 6. Here, "the thickness of the terminal electrode 7 is the same as the thickness of the upper electrode 6" is not limited to strictly the same case, and the thickness of the terminal electrode 7 is 95% of the thickness of the upper electrode 6. This includes cases where the thickness is within a range of 105% or more.
 また、圧電素子1aでは、端子電極7の厚さと上部電極6の厚さとが同じであることにより、金属基板2の上面21から端子電極7の上面71までの第1高さが、金属基板2の上面21から上部電極6の上面61までの第2高さと同じになっている。ここにおいて、第1高さが第2高さと同じとは、厳密に同じ場合のみに限定されず、第1高さが、第2高さの95%以上105%以下の範囲内の高さである場合を含む。 In the piezoelectric element 1a, since the thickness of the terminal electrode 7 and the thickness of the upper electrode 6 are the same, the first height from the upper surface 21 of the metal substrate 2 to the upper surface 71 of the terminal electrode 7 is It is the same as the second height from the upper surface 21 to the upper surface 61 of the upper electrode 6. Here, the first height being the same as the second height is not limited to strictly the same case, but the first height is within the range of 95% or more and 105% or less of the second height. Including some cases.
 端子電極7の材料は、上部電極6の材料と同じであり、例えば、Ag及びPdを含む。 The material of the terminal electrode 7 is the same as that of the upper electrode 6, and includes, for example, Ag and Pd.
 配線部8は、下部電極4の上面41と圧電体層5の側面53と圧電体層5の上面51とに跨って設けられており、下部電極4と端子電極7とをつないでいる。したがって、配線部8は、圧電体層5の上面51上に形成されている部分81を含む。配線部8は、圧電体層5の下面52には形成されていない。 The wiring section 8 is provided across the upper surface 41 of the lower electrode 4, the side surface 53 of the piezoelectric layer 5, and the upper surface 51 of the piezoelectric layer 5, and connects the lower electrode 4 and the terminal electrode 7. Therefore, the wiring section 8 includes a portion 81 formed on the upper surface 51 of the piezoelectric layer 5. The wiring portion 8 is not formed on the lower surface 52 of the piezoelectric layer 5.
 配線部8の材料は、上部電極6の材料及び端子電極7の材料と同じであり、例えば、Ag及びPdを含む。 The material of the wiring part 8 is the same as the material of the upper electrode 6 and the material of the terminal electrode 7, and includes, for example, Ag and Pd.
 図6に示すように、平面視で、配線部8は、金属基板2の外縁20よりも内側に位置している。平面視で、Y軸方向における配線部8の幅は、Y軸方向における端子電極7の幅よりも狭い。図7に示すように、Y軸方向からの側面視で、配線部8は、逆L字状である。 As shown in FIG. 6, the wiring portion 8 is located inside the outer edge 20 of the metal substrate 2 in plan view. In plan view, the width of the wiring portion 8 in the Y-axis direction is narrower than the width of the terminal electrode 7 in the Y-axis direction. As shown in FIG. 7, the wiring portion 8 has an inverted L shape when viewed from the side in the Y-axis direction.
 圧電素子1aでは、端子電極7及び配線部8は、スクリーン印刷によって上部電極6と同じ工程で形成されている。 In the piezoelectric element 1a, the terminal electrode 7 and the wiring portion 8 are formed in the same process as the upper electrode 6 by screen printing.
 圧電素子1aの製造方法は、圧電素子1の製造方法と略同じであり、圧電素子1の製造方法における第4工程で用いるスクリーンマスクの代わりに、上部電極6形成用の開口部と端子電極7形成用の開口部と配線部8形成用の開口部とを有するスクリーンマスクを利用する。圧電素子1aの製造方法における第4工程では、スキージを図6及び7の矢印B1の向きに移動させることによって、上部電極6、端子電極7及び配線部8それぞれの元になる上部電極材料部、端子電極材料部及び配線材料部を形成する。したがって、圧電素子1aの製造方法では、第3パターン部が、複数の上部電極材料部の他に、複数の端子電極材料部及び複数の配線材料部を含んでいる。 The manufacturing method of the piezoelectric element 1a is almost the same as the manufacturing method of the piezoelectric element 1, and instead of the screen mask used in the fourth step in the manufacturing method of the piezoelectric element 1, an opening for forming the upper electrode 6 and a terminal electrode 7 are used. A screen mask having an opening for forming the wiring portion 8 and an opening for forming the wiring portion 8 is used. In the fourth step in the method for manufacturing the piezoelectric element 1a, by moving the squeegee in the direction of arrow B1 in FIGS. A terminal electrode material portion and a wiring material portion are formed. Therefore, in the method for manufacturing the piezoelectric element 1a, the third pattern portion includes a plurality of terminal electrode material portions and a plurality of wiring material portions in addition to the plurality of upper electrode material portions.
 圧電素子1aの製造方法では、第1パターン部、第2パターン部及び第3パターン部を所定の焼成温度(例えば、875℃)で焼成することによって、複数の下部電極4を含む下部電極パターン部4A(図3参照)、複数の圧電体層5を含む圧電体層パターン部5A(図3参照)、複数の上部電極6を含む上部電極パターン部6A(図3参照)、複数の端子電極7を含む端子電極パターン部及び複数の配線部8を含む配線パターン部を形成する。これにより、複数の圧電素子1aを含む構造体が形成される。 In the method for manufacturing the piezoelectric element 1a, the lower electrode pattern portion including the plurality of lower electrodes 4 is formed by firing the first pattern portion, the second pattern portion, and the third pattern portion at a predetermined firing temperature (for example, 875° C.). 4A (see FIG. 3), a piezoelectric layer pattern section 5A (see FIG. 3) including a plurality of piezoelectric layers 5, an upper electrode pattern section 6A (see FIG. 3) including a plurality of upper electrodes 6, and a plurality of terminal electrodes 7. A terminal electrode pattern section including a terminal electrode pattern section and a wiring pattern section including a plurality of wiring sections 8 are formed. As a result, a structure including a plurality of piezoelectric elements 1a is formed.
 (1.2)超音波トランスデューサ
 実施形態2に係る超音波トランスデューサ100aは、図8及び9に示すように、第1導電性接合部131aが端子電極7上に配置されている点で、実施形態1に係る超音波トランスデューサ100(図4及び5参照)と相違する。
(1.2) Ultrasonic transducer As shown in FIGS. 8 and 9, the ultrasonic transducer 100a according to the second embodiment is different from the embodiment in that the first conductive joint 131a is disposed on the terminal electrode 7. This is different from the ultrasonic transducer 100 according to No. 1 (see FIGS. 4 and 5).
 実施形態2に係る超音波トランスデューサ100aでは、第1リード線141と端子電極7とが第1導電性接合部131aによって接合されている。第1導電性接合部131aの材料は、例えば、はんだを含む。 In the ultrasonic transducer 100a according to the second embodiment, the first lead wire 141 and the terminal electrode 7 are joined by the first conductive joint 131a. The material of the first conductive joint 131a includes, for example, solder.
 (2)効果
 (2.1)圧電素子
 実施形態2に係る圧電素子1aは、鉄とクロムとアルミニウムとを含む金属基板2を備える。実施形態2に係る圧電素子1aでは、平面視で、下部電極4の外縁40が、金属基板2の外縁20よりも内側に位置し、圧電体層5の外縁50が、下部電極4の外縁40よりも内側に位置し、上部電極6の外縁60が、圧電体層5の外縁50よりも内側に位置し、端子電極7及び配線部8が金属基板2の外縁20よりも内側に位置している。これにより、実施形態2に係る圧電素子1aによれば、圧電素子1aの動作周波数(共振周波数)の高速化を図ることが可能となる。より詳細には、実施形態2に係る圧電素子1aは、実施形態1に係る圧電素子1と同様、圧電体層5の薄型化を図ることができるので、圧電素子1aの共振周波数をより高くすることが可能となり、駆動周波数をより高くすることが可能となる。
(2) Effects (2.1) Piezoelectric Element The piezoelectric element 1a according to the second embodiment includes a metal substrate 2 containing iron, chromium, and aluminum. In the piezoelectric element 1a according to the second embodiment, in plan view, the outer edge 40 of the lower electrode 4 is located inside the outer edge 20 of the metal substrate 2, and the outer edge 50 of the piezoelectric layer 5 is located inside the outer edge 40 of the lower electrode 4. The outer edge 60 of the upper electrode 6 is located inside the outer edge 50 of the piezoelectric layer 5, and the terminal electrode 7 and the wiring portion 8 are located inside the outer edge 20 of the metal substrate 2. There is. Thereby, according to the piezoelectric element 1a according to the second embodiment, it is possible to increase the operating frequency (resonant frequency) of the piezoelectric element 1a. More specifically, in the piezoelectric element 1a according to the second embodiment, the piezoelectric layer 5 can be made thinner, similar to the piezoelectric element 1 according to the first embodiment, so that the resonant frequency of the piezoelectric element 1a can be made higher. This makes it possible to increase the driving frequency.
 また、圧電素子1aは、端子電極7及び配線部8を備え、端子電極7及び配線部8が金属基板2の外縁20よりも内側に位置しているので、折り返し電極を形成する必要がなく、製造が容易になるとともに、圧電素子1aのハンドリング時の端子電極7及び配線部8の破損を防止することが可能となる。 Moreover, the piezoelectric element 1a includes the terminal electrode 7 and the wiring part 8, and since the terminal electrode 7 and the wiring part 8 are located inside the outer edge 20 of the metal substrate 2, there is no need to form a folded electrode. Manufacturing becomes easier, and it becomes possible to prevent damage to the terminal electrode 7 and wiring portion 8 during handling of the piezoelectric element 1a.
 また、圧電素子1aでは、金属基板2の上面21から端子電極7の上面71までの第1高さが、金属基板2の上面21から上部電極6の上面61までの第2高さと同じなので、例えば、第1リード電極(第1導体部)及び第2リード電極(第2導体部)を含むフレキシブルプリント配線板への実装が容易になるとともに、接続信頼性を向上させることが可能となる。圧電素子1aをフレキシブルプリント配線板へ実装する場合には、フレキシブルプリント配線板に含まれる第1リード電極(第1導体部)及び第2リード電極(第2導体部)が、第1リード線141及び第2リード線142の代わりに、圧電素子1aの端子電極7及び上部電極6に、第1導電性接合部131a及び第2導電性接合部132によって接合される。 Furthermore, in the piezoelectric element 1a, the first height from the upper surface 21 of the metal substrate 2 to the upper surface 71 of the terminal electrode 7 is the same as the second height from the upper surface 21 of the metal substrate 2 to the upper surface 61 of the upper electrode 6. For example, mounting on a flexible printed wiring board including a first lead electrode (first conductor part) and a second lead electrode (second conductor part) becomes easier, and connection reliability can be improved. When mounting the piezoelectric element 1a on a flexible printed wiring board, the first lead electrode (first conductor part) and the second lead electrode (second conductor part) included in the flexible printed wiring board are connected to the first lead wire 141. And instead of the second lead wire 142, it is joined to the terminal electrode 7 and the upper electrode 6 of the piezoelectric element 1a by the first conductive joint 131a and the second conductive joint 132.
 また、実施形態2に係る圧電素子1aでは、平面視で、端子電極7は、圧電体層5の外縁50よりも内側に位置している。配線部8は、圧電体層5の上面51に設けられている部分81を含む。これにより、実施形態2に係る圧電素子1aは、端子電極7の厚さの均一性を向上させることが可能となる。 Furthermore, in the piezoelectric element 1a according to the second embodiment, the terminal electrode 7 is located inside the outer edge 50 of the piezoelectric layer 5 in plan view. The wiring portion 8 includes a portion 81 provided on the upper surface 51 of the piezoelectric layer 5 . Thereby, the piezoelectric element 1a according to the second embodiment can improve the uniformity of the thickness of the terminal electrode 7.
 また、実施形態2に係る圧電素子1aは、特許文献1に開示された折り返し電極の構造を採用することなく、下部電極4に接続された端子電極7が圧電体層5の上面51上に配置された構成を実現することができる。 Furthermore, in the piezoelectric element 1a according to the second embodiment, the terminal electrode 7 connected to the lower electrode 4 is arranged on the upper surface 51 of the piezoelectric layer 5 without adopting the folded electrode structure disclosed in Patent Document 1. It is possible to realize the following configuration.
 (2.2)超音波トランスデューサ
 実施形態2に係る超音波トランスデューサ100aは、圧電素子1aと、圧電素子1aの金属基板2と接合されている振動板部120と、を備えるので、圧電素子1aの動作周波数(共振周波数)の高速化を図ることが可能となる。これにより、超音波トランスデューサ100aでは、圧電素子1aの駆動周波数をより高くすることが可能となり、超音波の指向角の挟角化を図ることが可能となる。よって、例えば、超音波トランスデューサ100aを備える超音波センサを自動車に設置して用いる場合に、超音波トランスデューサ100aから送波された超音波が路面に入射して反射されることを抑制できる。これにより、超音波センサのS/N比を向上させることが可能となり、物体を検知可能な距離をより長くすることが可能となる。
(2.2) Ultrasonic transducer The ultrasonic transducer 100a according to the second embodiment includes the piezoelectric element 1a and the diaphragm portion 120 joined to the metal substrate 2 of the piezoelectric element 1a. It becomes possible to increase the operating frequency (resonant frequency). Thereby, in the ultrasonic transducer 100a, it becomes possible to increase the driving frequency of the piezoelectric element 1a, and it becomes possible to narrow the directivity angle of the ultrasonic waves. Therefore, for example, when an ultrasonic sensor including the ultrasonic transducer 100a is installed and used in a car, it is possible to suppress the ultrasonic waves transmitted from the ultrasonic transducer 100a from entering the road surface and being reflected. Thereby, it becomes possible to improve the S/N ratio of the ultrasonic sensor, and it becomes possible to further increase the distance at which an object can be detected.
 また、実施形態2に係る超音波トランスデューサ100aでは、圧電素子1aにおける金属基板2の上面21から端子電極7の上面71までの第1高さが、金属基板2の上面21から上部電極6の上面61までの第2高さと同じである。これにより、実施形態2に係る超音波トランスデューサ100aでは、第1導通部材及び第2導通部材として、第1リード線141及び第2リード線142の代わりに、例えば、フレキシブルプリント配線板第1リード電極(第1導体部)及び第2リード電極(第2導体部)を採用する場合に、フレキシブルプリント配線板への実装が容易になるとともに、接続信頼性の向上を図れる。 Further, in the ultrasonic transducer 100a according to the second embodiment, the first height from the upper surface 21 of the metal substrate 2 to the upper surface 71 of the terminal electrode 7 in the piezoelectric element 1a is from the upper surface 21 of the metal substrate 2 to the upper surface of the upper electrode 6. It is the same as the second height up to 61. As a result, in the ultrasonic transducer 100a according to the second embodiment, for example, the first lead wire of the flexible printed wiring board is used instead of the first lead wire 141 and the second lead wire 142 as the first conductive member and the second conductive member. (first conductor part) and second lead electrode (second conductor part), mounting on a flexible printed wiring board becomes easy and connection reliability can be improved.
 (実施形態3)
 実施形態3に係る圧電素子1bについて、図10を参照して説明する。実施形態3に係る圧電素子1bに関し、実施形態1に係る圧電素子1(図1及び2参照)と同様の構成要素については、同一の符号を付して説明を適宜省略する。
(Embodiment 3)
A piezoelectric element 1b according to Embodiment 3 will be described with reference to FIG. 10. Regarding the piezoelectric element 1b according to the third embodiment, the same components as those of the piezoelectric element 1 according to the first embodiment (see FIGS. 1 and 2) are designated by the same reference numerals, and the description thereof will be omitted as appropriate.
 (1)構成
 実施形態3に係る圧電素子1bでは、圧電体層5が、下部電極4の上面41の一部を露出させる開口部54を有する点で、実施形態1に係る圧電素子1と相違する。
(1) Configuration The piezoelectric element 1b according to the third embodiment is different from the piezoelectric element 1 according to the first embodiment in that the piezoelectric layer 5 has an opening 54 that exposes a part of the upper surface 41 of the lower electrode 4. do.
 圧電体層5の開口部54は、圧電体層5の厚さ方向に沿って形成されている。平面視で、開口部54の開口形状は、四角形状であるが、これに限らず、例えば、円形状であってもよい。圧電素子1bでは、下部電極4において圧電体層5の開口部54により露出した下部電極4の一部(部位411b)が、端子部を構成する。 The opening 54 of the piezoelectric layer 5 is formed along the thickness direction of the piezoelectric layer 5. In plan view, the opening shape of the opening portion 54 is square, but is not limited to this, and may be circular, for example. In the piezoelectric element 1b, a portion of the lower electrode 4 (portion 411b) exposed through the opening 54 of the piezoelectric layer 5 constitutes a terminal portion.
 圧電素子1bの製造方法は、圧電素子1の製造方法と略同じであり、圧電素子1の製造方法における第3工程で用いるスクリーンマスクのパターンを変更することにより、圧電体層5の開口部54を形成することができる。 The method for manufacturing the piezoelectric element 1b is substantially the same as the method for manufacturing the piezoelectric element 1, and by changing the pattern of the screen mask used in the third step in the method for manufacturing the piezoelectric element 1, the openings 54 of the piezoelectric layer 5 are can be formed.
 (2)効果
 実施形態3に係る圧電素子1bは、鉄とクロムとアルミニウムとを含む金属基板2を備える。実施形態3に係る圧電素子1bでは、平面視で、下部電極4の外縁40が、金属基板2の外縁20よりも内側に位置し、圧電体層5の外縁50が、下部電極4の外縁40よりも内側に位置し、上部電極6の外縁60が、圧電体層5の外縁50よりも内側に位置している。これにより、実施形態3に係る圧電素子1bによれば、圧電素子1bの動作周波数(共振周波数)の高速化を図ることが可能となる。より詳細には、実施形態3に係る圧電素子1bは、実施形態1に係る圧電素子1と同様、圧電体層5の薄型化を図ることができるので、圧電素子1bの共振周波数をより高くすることが可能となり、駆動周波数をより高くすることが可能となる。
(2) Effects The piezoelectric element 1b according to the third embodiment includes a metal substrate 2 containing iron, chromium, and aluminum. In the piezoelectric element 1b according to the third embodiment, in plan view, the outer edge 40 of the lower electrode 4 is located inside the outer edge 20 of the metal substrate 2, and the outer edge 50 of the piezoelectric layer 5 is located inside the outer edge 40 of the lower electrode 4. The outer edge 60 of the upper electrode 6 is located inner than the outer edge 50 of the piezoelectric layer 5 . Thereby, according to the piezoelectric element 1b according to the third embodiment, it is possible to increase the operating frequency (resonant frequency) of the piezoelectric element 1b. More specifically, in the piezoelectric element 1b according to the third embodiment, the piezoelectric layer 5 can be made thinner, similar to the piezoelectric element 1 according to the first embodiment, so that the resonant frequency of the piezoelectric element 1b can be made higher. This makes it possible to increase the driving frequency.
 また、実施形態3に係る圧電素子1bは、圧電体層5が、下部電極4の上面41の一部を露出させる開口部54を有するので、下部電極4の上面41の一部を端子部として兼用することができる。これにより、実施形態3に係る圧電素子1bは、実施形態1に係る圧電素子1と比べて、端子部として機能する領域を狭くすることが可能となり、使用時の特性のばらつきを抑制することが可能となる。 Furthermore, in the piezoelectric element 1b according to the third embodiment, since the piezoelectric layer 5 has an opening 54 that exposes a part of the upper surface 41 of the lower electrode 4, the part of the upper surface 41 of the lower electrode 4 can be used as a terminal part. Can be used for both purposes. As a result, the piezoelectric element 1b according to the third embodiment can have a narrower region functioning as a terminal part than the piezoelectric element 1 according to the first embodiment, and can suppress variations in characteristics during use. It becomes possible.
 (実施形態4)
 以下、実施形態4に係る超音波トランスデューサ100cについて、図12を参照しながら説明する。なお、実施形態4に係る超音波トランスデューサ100cに関し、実施形態1に係る超音波トランスデューサ100と同様の構成要素には、同一の符号を付して説明を適宜省略する。
(Embodiment 4)
An ultrasonic transducer 100c according to Embodiment 4 will be described below with reference to FIG. 12. Regarding the ultrasonic transducer 100c according to the fourth embodiment, the same components as those of the ultrasonic transducer 100 according to the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.
 実施形態4に係る超音波トランスデューサ100cは、実施形態1に係る超音波トランスデューサ100における振動板部120の代わりに、底面が開口した円錐状の振動板部120cを備える。 The ultrasonic transducer 100c according to the fourth embodiment includes a conical diaphragm section 120c with an open bottom in place of the diaphragm section 120 in the ultrasonic transducer 100 according to the first embodiment.
 また、実施形態4に係る超音波トランスデューサ100cは、実施形態1に係る超音波トランスデューサ100におけるケース101の代わりに、ケース101cを備える。 Furthermore, the ultrasonic transducer 100c according to the fourth embodiment includes a case 101c instead of the case 101 in the ultrasonic transducer 100 according to the first embodiment.
 超音波トランスデューサ100cでは、ケース101c内に、圧電素子1及び振動板部120cが収容されている。振動板部120cは、圧電素子1の金属基板2の下面22に接合されている。振動板部120cは、ケース101cとは別部材であり、ケース101cから離れている。 In the ultrasonic transducer 100c, the piezoelectric element 1 and the diaphragm portion 120c are housed in the case 101c. The diaphragm portion 120c is joined to the lower surface 22 of the metal substrate 2 of the piezoelectric element 1. The diaphragm portion 120c is a separate member from the case 101c and is separated from the case 101c.
 ケース101cは、台座170と、キャップ106と、メッシュ部材165と、を含む。また、超音波トランスデューサ100cは、台座170から突出しており、圧電素子1を支持している支持部180を備える。また、超音波トランスデューサ100cは、第1導電性接合部131及び第2導電性接合部132と、第1リード線141及び第2リード線142と、第1リード端子191及び第2リード端子192と、を備える。 The case 101c includes a pedestal 170, a cap 106, and a mesh member 165. The ultrasonic transducer 100c also includes a support portion 180 that protrudes from the pedestal 170 and supports the piezoelectric element 1. The ultrasonic transducer 100c also includes a first conductive joint 131 and a second conductive joint 132, a first lead wire 141 and a second lead wire 142, a first lead terminal 191 and a second lead terminal 192. , is provided.
 台座170は、円盤状である。台座170の材料は、例えば、アルミニウム合金であるが、これに限らず、例えば、マグネシウム合金、ステンレス鋼、チタン合金又はエンジニアプラスチックでもよい。 The pedestal 170 is disc-shaped. The material of the pedestal 170 is, for example, an aluminum alloy, but is not limited thereto, and may be, for example, a magnesium alloy, stainless steel, a titanium alloy, or an engineered plastic.
 キャップ106は、底壁161と円筒状の周壁162とを有する有底円筒状であり、圧電素子1及び振動板部120cを覆うように台座170に固着されている。キャップ106の材料は、例えば、アルミニウム合金であるが、これに限らず、例えば、マグネシウム合金、ステンレス鋼、チタン合金又はエンジニアプラスチックでもよい。 The cap 106 has a bottomed cylindrical shape having a bottom wall 161 and a cylindrical peripheral wall 162, and is fixed to the pedestal 170 so as to cover the piezoelectric element 1 and the diaphragm portion 120c. The material of the cap 106 is, for example, an aluminum alloy, but is not limited thereto, and may be, for example, a magnesium alloy, stainless steel, a titanium alloy, or an engineered plastic.
 メッシュ部材165は、キャップ106の底壁161に形成された窓孔163内に配置されており、振動板部120cの前方に位置している。メッシュ部材165は、超音波を通すことができるように複数の開口部166を有する。 The mesh member 165 is disposed within a window hole 163 formed in the bottom wall 161 of the cap 106, and is located in front of the diaphragm portion 120c. The mesh member 165 has a plurality of openings 166 to allow ultrasound to pass therethrough.
 第1リード線141及び第2リード線142は、可撓性を有する電線である。超音波トランスデューサ100cでは、第1リード線141の第1端は、第1導電性接合部131により圧電素子1の下部電極4に接合されて電気的に接続され、第1リード線141の第2端は、第1リード端子191に接合されて電気的に接続されている。また、超音波トランスデューサ100cでは、第2リード線142の第1端は、第2導電性接合部132により圧電素子1の上部電極6に接合されて電気的に接続され、第2リード線142の第2端は、第2リード端子192に接合されて電気的に接続されている。 The first lead wire 141 and the second lead wire 142 are flexible electric wires. In the ultrasonic transducer 100c, the first end of the first lead wire 141 is joined and electrically connected to the lower electrode 4 of the piezoelectric element 1 by the first conductive joint 131, and the second end of the first lead wire 141 The end is joined to the first lead terminal 191 and electrically connected. Further, in the ultrasonic transducer 100c, the first end of the second lead wire 142 is joined and electrically connected to the upper electrode 6 of the piezoelectric element 1 by the second conductive joint portion 132. The second end is joined to and electrically connected to the second lead terminal 192.
 第1リード端子191及び第2リード端子192の各々は、ピン状である。第1リード端子191及び第2リード端子192は、台座170の厚さ方向において台座170を貫通している。第1リード端子191と第2リード端子192とは電気的に絶縁されている。第1リード端子191及び第2リード端子192は、台座170とは第1リード端子191及び第2リード端子192と台座170との間に介在する第1絶縁部及び第2絶縁部により電気的に絶縁されているが、これに限らない。例えば、第1リード端子191及び第2リード端子192のうちの一方が台座170と電気的に接続されていてもよい。 Each of the first lead terminal 191 and the second lead terminal 192 is pin-shaped. The first lead terminal 191 and the second lead terminal 192 penetrate the base 170 in the thickness direction of the base 170. The first lead terminal 191 and the second lead terminal 192 are electrically insulated. The first lead terminal 191 and the second lead terminal 192 are electrically connected to the pedestal 170 by the first insulating part and the second insulating part interposed between the first lead terminal 191 and the second lead terminal 192 and the pedestal 170. Although it is insulated, it is not limited to this. For example, one of the first lead terminal 191 and the second lead terminal 192 may be electrically connected to the base 170.
 実施形態4に係る超音波トランスデューサ100cは、圧電素子1と、圧電素子1の金属基板2と接合されている振動板部120cと、を備えるので、圧電素子1の動作周波数(共振周波数)の高速化を図ることが可能となる。これにより、超音波トランスデューサ100cでは、圧電素子1の駆動周波数をより高くすることが可能となり、超音波の指向角の挟角化を図ることが可能となる。 The ultrasonic transducer 100c according to the fourth embodiment includes the piezoelectric element 1 and the diaphragm portion 120c joined to the metal substrate 2 of the piezoelectric element 1, so that the operating frequency (resonant frequency) of the piezoelectric element 1 can be adjusted to a high speed. This makes it possible to achieve Thereby, in the ultrasonic transducer 100c, it becomes possible to increase the driving frequency of the piezoelectric element 1, and it becomes possible to narrow the directivity angle of the ultrasonic waves.
 (変形例)
 実施形態1~4は、本開示の様々な実施形態の一つに過ぎない。実施形態1~4は、本開示の目的を達成できれば、設計等に応じて種々の変更が可能である。
(Modified example)
Embodiments 1-4 are just one of various embodiments of the present disclosure. Embodiments 1 to 4 can be modified in various ways depending on the design, etc., as long as the objective of the present disclosure can be achieved.
 例えば、平面視での金属基板2の外縁20は、長方形状である場合に限らず、例えば、正方形状であってもよいし、円形状、楕円状又は長円状であってもよい。 For example, the outer edge 20 of the metal substrate 2 in plan view is not limited to a rectangular shape, and may be, for example, square, circular, elliptical, or oval.
 金属基板2は、アルミニウムを含むことは必須ではなく、少なくとも鉄及びクロムを含んでいればよい。 The metal substrate 2 does not necessarily need to contain aluminum, but only needs to contain at least iron and chromium.
 また、圧電素子1、1a、1bにおいてアルミナ層3を含むことは必須ではない。つまり、圧電素子1、1a、1bは、アルミナ層3を含まず、下部電極4が金属基板2上に直接設けられていてもよい。 Furthermore, it is not essential that the piezoelectric elements 1, 1a, and 1b include the alumina layer 3. That is, the piezoelectric elements 1, 1a, and 1b may not include the alumina layer 3, and the lower electrode 4 may be provided directly on the metal substrate 2.
 また、圧電体層5の材料は、PbとZrとZnとNbとOとを含む材料、例えば、Pb1.015Zr0.44(Zn1/3Nb2/30.103.015に限らず、チタン酸ジルコン酸鉛(PZT)、チタン酸バリウム、マグネシウムニオブ酸鉛(PMN)、KNbO、NaNbO又はK0.5Na0.5NbOであってもよい。 The material of the piezoelectric layer 5 is a material containing Pb, Zr, Zn, Nb, and O, for example, Pb 1.015 Zr 0.44 (Zn 1/3 Nb 2/3 ) 0.10 O 3. 015 , but may be lead zirconate titanate (PZT), barium titanate, lead magnesium niobate (PMN), KNbO 3 , NaNbO 3 or K 0.5 Na 0.5 NbO 3 .
 また、圧電素子1、1a、1bでは、圧電体層5が下部電極4上に直接設けられているが、これに限らず、圧電体層5がバッファ層を介して下部電極4上に設けられていてもよい。バッファ層は、例えば、下部電極4の材料の少なくとも一部と圧電体層5の材料の少なくとも一部とを含む。 Furthermore, in the piezoelectric elements 1, 1a, and 1b, the piezoelectric layer 5 is provided directly on the lower electrode 4; however, the piezoelectric layer 5 is not limited to this, and the piezoelectric layer 5 may be provided on the lower electrode 4 via a buffer layer. You can leave it there. The buffer layer includes, for example, at least a portion of the material of the lower electrode 4 and at least a portion of the material of the piezoelectric layer 5.
 また、圧電素子1aでは、配線部8は、下部電極4の上面41と圧電体層5の側面53と圧電体層5の上面51とに跨って設けられている構成に限らない。例えば、配線部8は、下部電極4と端子電極7とをつないでおり、かつ、圧電体層5の下面52に設けられていなければよく、少なくとも下部電極4の上面41と圧電体層5の側面53とに跨って設けられていればよい。 Furthermore, in the piezoelectric element 1a, the wiring portion 8 is not limited to the configuration in which it is provided across the upper surface 41 of the lower electrode 4, the side surface 53 of the piezoelectric layer 5, and the upper surface 51 of the piezoelectric layer 5. For example, it is sufficient that the wiring portion 8 connects the lower electrode 4 and the terminal electrode 7 and is not provided on the lower surface 52 of the piezoelectric layer 5. It suffices if it is provided astride the side surface 53.
 また、圧電素子1bは、圧電体層5の外縁50のうち開口部54の近い部分と圧電体層5の開口部54との間の狭い部分を有することは必須ではなく、開口部54が上方及び側方へ開放されていてもよい。 Furthermore, it is not essential for the piezoelectric element 1b to have a narrow portion between the outer edge 50 of the piezoelectric layer 5 near the opening 54 and the opening 54 of the piezoelectric layer 5; and may be opened laterally.
 超音波トランスデューサ100、100aにおいて、第1導通部材及び第2導通部材は、第1リード線141及び第2リード線142に限らず、例えば、フレキシブルプリント配線板の導体パターン部に含まれる第1リード電極(第1導体部)及び第2リード電極(第2導体部)であってもよい。 In the ultrasonic transducer 100, 100a, the first conductive member and the second conductive member are not limited to the first lead wire 141 and the second lead wire 142, but are, for example, the first lead included in the conductor pattern portion of the flexible printed wiring board. It may be an electrode (first conductor part) and a second lead electrode (second conductor part).
 また、超音波トランスデューサ100cにおいて、第1導通部材及び第2導通部材は、第1リード線141及び第2リード線142に限らず、例えば、第1導電性ワイヤ及び第2導電性ワイヤであってもよい。 Further, in the ultrasonic transducer 100c, the first conductive member and the second conductive member are not limited to the first lead wire 141 and the second lead wire 142, but are, for example, a first conductive wire and a second conductive wire. Good too.
 また、超音波トランスデューサ100cは、圧電素子1の代わりに、圧電素子1a又は圧電素子1bを備えていてもよい。 Further, the ultrasonic transducer 100c may include a piezoelectric element 1a or a piezoelectric element 1b instead of the piezoelectric element 1.
 (態様)
 以上説明した実施形態1~4等から、本明細書には以下の態様が開示されている。
(mode)
From Embodiments 1 to 4 described above, the following aspects are disclosed in this specification.
 第1の態様に係る圧電素子(1;1a;1b)は、金属基板(2)と、下部電極(4)と、圧電体層(5)と、上部電極(6)と、を備える。金属基板(2)は、少なくとも鉄及びクロムを含む。下部電極(4)は、金属基板(2)上に設けられている。圧電体層(5)は、下部電極(4)上に設けられている。上部電極(6)は、圧電体層(5)上に設けられている。平面視で、下部電極(4)の第1外縁(外縁40)は、金属基板2の第2外縁(外縁20)よりも内側に位置している。平面視で、圧電体層(5)の第3外縁(外縁50)は、下部電極(4)の第1外縁(外縁40)よりも内側に位置している。平面視で、上部電極(6)の第4外縁(外縁60)は、圧電体層(5)の第3外縁(外縁50)よりも内側に位置している。 The piezoelectric element (1; 1a; 1b) according to the first aspect includes a metal substrate (2), a lower electrode (4), a piezoelectric layer (5), and an upper electrode (6). The metal substrate (2) contains at least iron and chromium. The lower electrode (4) is provided on the metal substrate (2). The piezoelectric layer (5) is provided on the lower electrode (4). The upper electrode (6) is provided on the piezoelectric layer (5). In plan view, the first outer edge (outer edge 40) of the lower electrode (4) is located inside the second outer edge (outer edge 20) of the metal substrate 2. In plan view, the third outer edge (outer edge 50) of the piezoelectric layer (5) is located inside the first outer edge (outer edge 40) of the lower electrode (4). In plan view, the fourth outer edge (outer edge 60) of the upper electrode (6) is located inside the third outer edge (outer edge 50) of the piezoelectric layer (5).
 第1の態様に係る圧電素子(1;1a;1b)によれば、圧電素子(1;1a;1b)の動作周波数の高速化を図ることが可能となる。 According to the piezoelectric element (1; 1a; 1b) according to the first aspect, it is possible to increase the operating frequency of the piezoelectric element (1; 1a; 1b).
 第2の態様に係る圧電素子(1;1a;1b)は、第1の態様において、アルミナ層(3)を更に含む。アルミナ層(3)は、金属基板(2)と下部電極(4)との間に介在している。金属基板(2)は、アルミニウムを更に含む。アルミナ層(3)の上面(31)は、アルミナ層(3)の有する複数の鱗片状の粒子の表面の一部を含む。 The piezoelectric element (1; 1a; 1b) according to the second embodiment further includes an alumina layer (3) in the first embodiment. The alumina layer (3) is interposed between the metal substrate (2) and the lower electrode (4). The metal substrate (2) further contains aluminum. The upper surface (31) of the alumina layer (3) includes a part of the surface of the plurality of scale-like particles of the alumina layer (3).
 第2の態様に係る圧電素子(1;1a;1b)は、下部電極(4)の剥離を抑制することが可能となる。 The piezoelectric element (1; 1a; 1b) according to the second aspect can suppress peeling of the lower electrode (4).
 第3の態様に係る圧電素子(1;1a;1b)では、第2の態様において、アルミナ層(3)は、金属基板(2)の上面(21)の全域を覆っている。 In the piezoelectric element (1; 1a; 1b) according to the third aspect, in the second aspect, the alumina layer (3) covers the entire upper surface (21) of the metal substrate (2).
 第3の態様に係る圧電素子(1;1a;1b)では、圧電特性を向上させることが可能となる。 In the piezoelectric element (1; 1a; 1b) according to the third aspect, it is possible to improve piezoelectric characteristics.
 第4の態様に係る圧電素子(1a)は、第1~3の態様のいずれか一つにおいて、端子電極(7)と、配線部(8)と、を更に備える。端子電極(7)は、圧電体層(5)上に設けられており、上部電極(6)から離れている。配線部(8)は、下部電極(4)の上面(41)と圧電体層(5)の側面(53)とに跨って設けられており、下部電極(4)と端子電極(7)とをつないでいる。平面視で、配線部(8)は、金属基板(2)の第2外縁(外縁20)よりも内側に位置している。 The piezoelectric element (1a) according to the fourth aspect, in any one of the first to third aspects, further includes a terminal electrode (7) and a wiring part (8). The terminal electrode (7) is provided on the piezoelectric layer (5) and is separated from the upper electrode (6). The wiring section (8) is provided across the upper surface (41) of the lower electrode (4) and the side surface (53) of the piezoelectric layer (5), and is connected between the lower electrode (4) and the terminal electrode (7). are connected. In plan view, the wiring portion (8) is located inside the second outer edge (outer edge 20) of the metal substrate (2).
 第4の態様に係る圧電素子(1a)では、フレキシブルプリント配線板への実装が容易になるとともに、接続信頼性を向上させることが可能となる。 The piezoelectric element (1a) according to the fourth aspect can be easily mounted on a flexible printed wiring board and can improve connection reliability.
 第5の態様に係る圧電素子(1a)では、第4の態様において、平面視で、端子電極(7)は、圧電体層(5)の第3外縁(外縁50)よりも内側に位置している。配線部(8)は、圧電体層(5)の上面(51)に設けられている部分(81)を含む。 In the piezoelectric element (1a) according to the fifth aspect, in the fourth aspect, the terminal electrode (7) is located inside the third outer edge (outer edge 50) of the piezoelectric layer (5) in plan view. ing. The wiring portion (8) includes a portion (81) provided on the upper surface (51) of the piezoelectric layer (5).
 第5の態様に係る圧電素子(1a)では、端子電極(7)の厚さの均一性を向上させることが可能となる。 In the piezoelectric element (1a) according to the fifth aspect, it is possible to improve the uniformity of the thickness of the terminal electrode (7).
 第6の態様に係る圧電素子(1b)では、第1~3の態様のいずれか一つにおいて、圧電体層(5)は、下部電極(4)の上面(41)の一部を露出させる開口部(54)を有する。 In the piezoelectric element (1b) according to the sixth aspect, in any one of the first to third aspects, the piezoelectric layer (5) exposes a part of the upper surface (41) of the lower electrode (4). It has an opening (54).
 第6の態様に係る圧電素子(1b)では、下部電極(4)の上面(41)の一部が端子部を構成するので、端子部として機能する領域を狭くすることが可能となり、使用時の特性のばらつきを抑制することが可能となる。 In the piezoelectric element (1b) according to the sixth aspect, since a part of the upper surface (41) of the lower electrode (4) constitutes the terminal part, it is possible to narrow the area that functions as the terminal part, and when in use This makes it possible to suppress variations in the characteristics of.
 第7の態様に係る超音波トランスデューサ(100;100a;100c)は、第1~6の態様のいずれか一つの圧電素子(1;1a;1b)と、振動板部(120;120c)と、第1導通部材(第1リード線141)と、第2導通部材(第2リード線142)と、第1導電性接合部(131)と、第2導電性接合部(132)と、を備える。振動板部(120;120c)は、圧電素子(1;1a;1b)の金属基板(2)と接合されている。第1導通部材(第1リード線141)は、圧電素子(1;1a;1b)の下部電極(4)に接続される。第2導通部材(第2リード線142)は、圧電素子(1;1a;1b)の上部電極(6)に接続される。第1導電性接合部(131)は、下部電極(4)と第1導通部材(第1リード線141)とを接合している。第2導電性接合部(132)は、上部電極(6)と第2導通部材(第2リード線142)とを接合している。 An ultrasonic transducer (100; 100a; 100c) according to a seventh aspect includes a piezoelectric element (1; 1a; 1b) according to any one of the first to sixth aspects, a diaphragm section (120; 120c), Includes a first conductive member (first lead wire 141), a second conductive member (second lead wire 142), a first conductive joint (131), and a second conductive joint (132). . The diaphragm portion (120; 120c) is joined to the metal substrate (2) of the piezoelectric element (1; 1a; 1b). The first conductive member (first lead wire 141) is connected to the lower electrode (4) of the piezoelectric element (1; 1a; 1b). The second conductive member (second lead wire 142) is connected to the upper electrode (6) of the piezoelectric element (1; 1a; 1b). The first conductive joint (131) joins the lower electrode (4) and the first conductive member (first lead wire 141). The second conductive joint (132) joins the upper electrode (6) and the second conductive member (second lead wire 142).
 第7の態様に係る超音波トランスデューサ(100;100a;100c)は、圧電素子(1;1a;1b)の動作周波数の高速化を図ることが可能となる。 The ultrasonic transducer (100; 100a; 100c) according to the seventh aspect can increase the operating frequency of the piezoelectric element (1; 1a; 1b).
 第8の態様に係る超音波トランスデューサ(100;100a)では、第7の態様において、圧電素子(1;1a;1b)を収容しているケース(101)を更に備える。ケース(101)は、底板部(102)と、筒部(103)と、を有する。底板部(102)は、平板状である。筒部(103)は、底板部(102)の一面の周部から底板部(102)の厚さ方向に突出しており、圧電素子(1;1a;1b)を囲んでいる。底板部(102)のうち筒部(103)により囲まれた部分が、振動板部(120)を兼ねている。 The ultrasonic transducer (100; 100a) according to the eighth aspect further includes a case (101) housing the piezoelectric element (1; 1a; 1b) in the seventh aspect. The case (101) has a bottom plate part (102) and a cylindrical part (103). The bottom plate portion (102) has a flat plate shape. The cylindrical portion (103) protrudes from the periphery of one surface of the bottom plate portion (102) in the thickness direction of the bottom plate portion (102), and surrounds the piezoelectric element (1; 1a; 1b). A portion of the bottom plate portion (102) surrounded by the cylinder portion (103) also serves as a diaphragm portion (120).
 第8の態様に係る超音波トランスデューサ(100;100a)は、例えば、車両に取り付けられて車両の外部の物体を検知する超音波センサに用いることができる。 The ultrasonic transducer (100; 100a) according to the eighth aspect can be used, for example, as an ultrasonic sensor that is attached to a vehicle and detects objects outside the vehicle.
 1、1a、1b 圧電素子
 2 金属基板
 20 外縁(第2外縁)
 3 アルミナ層
 30 外縁
 31 上面
 4 下部電極
 40 外縁(第1外縁)
 41 上面
 411 部位
 5 圧電体層
 50 外縁(第3外縁)
 51 上面
 53 側面
 54 開口部
 6 上部電極
 60 外縁(第4外縁)
 61 上面
 7 端子電極
 71 上面
 8 配線部
 81 部分
 9 空隙
 100、100a、100c 超音波トランスデューサ
 101、101c ケース
 102 底板部
 103 筒部
 120、120c 振動板部
 131 第1導電性接合部
 132 第2導電性接合部
 141 第1リード線(第1導通部材)
 142 第2リード線(第2導通部材)
1, 1a, 1b piezoelectric element 2 metal substrate 20 outer edge (second outer edge)
3 Alumina layer 30 Outer edge 31 Upper surface 4 Lower electrode 40 Outer edge (first outer edge)
41 Upper surface 411 Part 5 Piezoelectric layer 50 Outer edge (third outer edge)
51 Top surface 53 Side surface 54 Opening 6 Upper electrode 60 Outer edge (fourth outer edge)
61 Top surface 7 Terminal electrode 71 Top surface 8 Wiring section 81 Portion 9 Gap 100, 100a, 100c Ultrasonic transducer 101, 101c Case 102 Bottom plate section 103 Cylindrical section 120, 120c Vibration plate section 131 First conductive joint section 132 Second conductive section Joint part 141 First lead wire (first conductive member)
142 Second lead wire (second conductive member)

Claims (8)

  1.  少なくとも鉄及びクロムを含む金属基板と、
     前記金属基板上に設けられている下部電極と、
     前記下部電極上に設けられている圧電体層と、
     前記圧電体層上に設けられている上部電極と、を備え、
     平面視で、前記下部電極の第1外縁は、前記金属基板の第2外縁よりも内側に位置しており、
     前記平面視で、前記圧電体層の第3外縁は、前記下部電極の前記第1外縁よりも内側に位置しており、
     前記平面視で、前記上部電極の第4外縁は、前記圧電体層の前記第3外縁よりも内側に位置している、
     圧電素子。
    a metal substrate containing at least iron and chromium;
    a lower electrode provided on the metal substrate;
    a piezoelectric layer provided on the lower electrode;
    an upper electrode provided on the piezoelectric layer,
    In plan view, the first outer edge of the lower electrode is located inside the second outer edge of the metal substrate,
    In the plan view, the third outer edge of the piezoelectric layer is located inside the first outer edge of the lower electrode,
    In the plan view, the fourth outer edge of the upper electrode is located inside the third outer edge of the piezoelectric layer.
    Piezoelectric element.
  2.  前記金属基板と前記下部電極との間に介在しているアルミナ層を更に含み、
     前記金属基板は、アルミニウムを更に含み、
     前記アルミナ層の上面は、前記アルミナ層の有する複数の鱗片状の粒子の表面の一部を含む、
     請求項1に記載の圧電素子。
    further comprising an alumina layer interposed between the metal substrate and the lower electrode,
    The metal substrate further includes aluminum,
    The upper surface of the alumina layer includes a part of the surface of a plurality of scale-like particles of the alumina layer.
    The piezoelectric element according to claim 1.
  3.  前記アルミナ層は、前記金属基板の上面の全域を覆っている、
     請求項2に記載の圧電素子。
    The alumina layer covers the entire upper surface of the metal substrate,
    The piezoelectric element according to claim 2.
  4.  前記圧電体層上に設けられており、前記上部電極から離れている端子電極と、
     前記下部電極の上面と前記圧電体層の側面とに跨って設けられており、前記下部電極と前記端子電極とをつないでいる配線部と、を更に備え、
     前記平面視で、前記配線部は、前記金属基板の前記第2外縁よりも内側に位置している、
     請求項1~3のいずれか一項に記載の圧電素子。
    a terminal electrode provided on the piezoelectric layer and separated from the upper electrode;
    further comprising a wiring section provided across the upper surface of the lower electrode and the side surface of the piezoelectric layer and connecting the lower electrode and the terminal electrode,
    In the plan view, the wiring portion is located inside the second outer edge of the metal substrate.
    A piezoelectric element according to any one of claims 1 to 3.
  5.  前記平面視で、前記端子電極は、前記圧電体層の前記第3外縁よりも内側に位置しており、
     前記配線部は、前記圧電体層の上面に設けられている部分を含む、
     請求項4に記載の圧電素子。
    In the plan view, the terminal electrode is located inside the third outer edge of the piezoelectric layer,
    The wiring portion includes a portion provided on the top surface of the piezoelectric layer.
    The piezoelectric element according to claim 4.
  6.  前記圧電体層は、前記下部電極の上面の一部を露出させる開口部を有する、
     請求項1~3のいずれか一項に記載の圧電素子。
    The piezoelectric layer has an opening that exposes a part of the upper surface of the lower electrode.
    A piezoelectric element according to any one of claims 1 to 3.
  7.  請求項1~6のいずれか一項に記載の圧電素子と、
     前記圧電素子の前記金属基板と接合されている振動板部と、
     前記圧電素子の前記下部電極に接続される第1導通部材と、
     前記圧電素子の前記上部電極に接続される第2導通部材と、
     前記下部電極と前記第1導通部材とを接合している第1導電性接合部と、
     前記上部電極と前記第2導通部材とを接合している第2導電性接合部と、を備える、
     超音波トランスデューサ。
    A piezoelectric element according to any one of claims 1 to 6,
    a diaphragm portion joined to the metal substrate of the piezoelectric element;
    a first conductive member connected to the lower electrode of the piezoelectric element;
    a second conductive member connected to the upper electrode of the piezoelectric element;
    a first conductive joint that joins the lower electrode and the first conductive member;
    a second conductive joint that joins the upper electrode and the second conductive member;
    Ultrasonic transducer.
  8.  前記圧電素子を収容しているケースを更に備え、
     前記ケースは、
      平板状の底板部と、
      前記底板部の一面の周部から前記底板部の厚さ方向に突出しており、前記圧電素子を囲んでいる筒部と、を有し、
     前記底板部のうち前記筒部により囲まれた部分が、前記振動板部を兼ねている、
     請求項7に記載の超音波トランスデューサ。
    Further comprising a case housing the piezoelectric element,
    The said case is
    A flat bottom plate part,
    a cylindrical portion that protrudes from a peripheral portion of one surface of the bottom plate portion in the thickness direction of the bottom plate portion and surrounds the piezoelectric element;
    A portion of the bottom plate portion surrounded by the cylinder portion also serves as the diaphragm portion.
    The ultrasonic transducer according to claim 7.
PCT/JP2023/017878 2022-05-19 2023-05-12 Piezoelectric element and ultrasonic transducer WO2023223955A1 (en)

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* Cited by examiner, † Cited by third party
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JP2007037007A (en) * 2005-07-29 2007-02-08 Osaka Prefecture Piezoelectric sound wave sensor
JP2007165385A (en) * 2005-12-09 2007-06-28 Nec Tokin Corp Piezoelectric film lamination structure, and its manufacturing method
JP2011250327A (en) * 2010-05-28 2011-12-08 Murata Mfg Co Ltd Ultrasonic sensor
WO2012111279A1 (en) * 2011-02-18 2012-08-23 パナソニック株式会社 Piezoelectric element
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