WO2022210916A1 - Piezoelectric element and piezoelectric sensor - Google Patents

Piezoelectric element and piezoelectric sensor Download PDF

Info

Publication number
WO2022210916A1
WO2022210916A1 PCT/JP2022/016098 JP2022016098W WO2022210916A1 WO 2022210916 A1 WO2022210916 A1 WO 2022210916A1 JP 2022016098 W JP2022016098 W JP 2022016098W WO 2022210916 A1 WO2022210916 A1 WO 2022210916A1
Authority
WO
WIPO (PCT)
Prior art keywords
piezoelectric element
external electrode
piezoelectric
region
content
Prior art date
Application number
PCT/JP2022/016098
Other languages
French (fr)
Japanese (ja)
Inventor
将司 亀川
Original Assignee
京セラ株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 京セラ株式会社 filed Critical 京セラ株式会社
Priority to JP2023511496A priority Critical patent/JPWO2022210916A1/ja
Publication of WO2022210916A1 publication Critical patent/WO2022210916A1/en

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/16—Measuring force or stress, in general using properties of piezoelectric devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/06—Forming electrodes or interconnections, e.g. leads or terminals
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/06—Forming electrodes or interconnections, e.g. leads or terminals
    • H10N30/067—Forming single-layered electrodes of multilayered piezoelectric or electrostrictive parts
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/30—Piezoelectric or electrostrictive devices with mechanical input and electrical output, e.g. functioning as generators or sensors
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/40—Piezoelectric or electrostrictive devices with electrical input and electrical output, e.g. functioning as transformers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/853—Ceramic compositions
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals

Definitions

  • the disclosed embodiments relate to piezoelectric elements and piezoelectric sensors.
  • a piezoelectric element that has a laminated body in which a piezoelectric body and an internal electrode are laminated, and an external electrode connected to the internal electrode.
  • a piezoelectric element includes a laminate and an external electrode.
  • the laminate is formed by laminating a plurality of piezoelectric bodies and internal electrodes. External electrodes are positioned on the side surfaces of the laminate and connected to the internal electrodes.
  • the laminate has an active region sandwiched between the internal electrodes of different polarities and an inactive region sandwiched between the internal electrodes of the same polarity.
  • the internal electrodes contain Ag and Pd as main components.
  • An active portion of the internal electrode located in the active region is a first portion.
  • An inactive portion of the internal electrode positioned in the inactive region has a second portion having a higher Pd content than the first portion. The first portion has a higher Ag content than the second portion.
  • FIG. 1 is a cross-sectional view showing an example of a piezoelectric element according to an embodiment.
  • FIG. 2 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line AA.
  • FIG. 3 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line BB.
  • FIG. 4 is a cross-sectional view (part 1) showing an example of a piezoelectric element according to a modification of the embodiment;
  • FIG. 5 is a cross-sectional view (No. 2) showing an example of a piezoelectric element according to a modification of the embodiment.
  • FIG. 6 is a plan view showing an example of a piezoelectric element according to a modified example of the embodiment.
  • FIG. 7 is a cross-sectional view (No. 3) showing an example of a piezoelectric element according to a modification of the embodiment.
  • FIG. 8 is a cross-sectional view (part 4) showing an example of a piezoelectric element according to a modification of the embodiment.
  • FIG. 9 is a perspective view showing an example of the piezoelectric sensor according to the embodiment; 10 is a cross-sectional view of the piezoelectric sensor shown in FIG. 9 taken along the line CC.
  • FIG. 1 is a perspective view showing an example of a piezoelectric element according to an embodiment
  • FIG. FIG. 2 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line AA.
  • FIG. 3 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line BB. 2 corresponds to a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 along the ZX plane. 3 corresponds to a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 along the XY plane so as to include the internal electrodes 30.
  • FIG. 2 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line AA.
  • FIG. 3 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line BB. 2 corresponds to a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 along the ZX plane. 3 corresponds to
  • a piezoelectric element 1 includes a laminate 10 and an external electrode 40 .
  • the piezoelectric element 1 is, for example, a piezoelectric sensor that detects an external force applied to the laminate 10 and converts it into voltage.
  • the laminate 10 is formed by laminating a plurality of piezoelectric bodies 20 and internal electrodes 30 .
  • the piezoelectric body 20 is made of, for example, a ferroelectric ceramic material.
  • the internal electrode 30 contains Ag and Pd as main components.
  • the “main component” means that Ag and Pd are contained more than other components among the various components that constitute the internal electrode 30 .
  • another component it is glass, for example.
  • the total of Ag and Pd is 70% by mass, the remaining 30% by mass is glass.
  • the internal electrode 30 includes electrodes 31 to 34 .
  • the electrodes 31 to 34 are laminated in order with the piezoelectric body 20 interposed therebetween.
  • the electrodes 31 and 33 are electrically connected to an electrode 41 whose one end is the external electrode 40, and extend in the positive X-axis direction along the XY plane.
  • One end of the electrodes 32 and 34 is electrically connected to an electrode 42, which is the external electrode 40, and extends in the X-axis negative direction along the XY plane.
  • the external electrode 40 contains Au as a main component.
  • the external electrode 40 may be, for example, a so-called gold electrode containing more than 50% by mass, especially 90% by mass or more of Au or an Au alloy.
  • the external electrodes 40 may contain Pb (lead).
  • Pb lead
  • the external electrodes 40 are positioned on the side surfaces of the laminate 10 and connected to the internal electrodes 30 .
  • the external electrode 40 has electrodes 41 and 42 facing each other with the laminate 10 interposed therebetween.
  • the electrode 41 is located on the side surface of the laminate 10 on the negative side of the X-axis.
  • the electrode 42 is located on the side surface of the laminate 10 on the positive side of the X-axis.
  • the external electrodes 40 are formed along the side surfaces of the multilayer body 10, and are substantially rectangular long in the Y-axis direction, which is the direction in which the internal electrodes 30 are stacked, in the Y-axis direction so that the internal electrodes 30 are exposed to the outside of the multilayer body 10, as compared to the Z-axis direction. have a shape.
  • the laminate 10 has an active region 11 and an inactive region 12 .
  • the active region 11 is a region sandwiched between internal electrodes 30 having different polarities. Specifically, the active region 11 is a portion where the adjacent internal electrodes 30 face each other.
  • the inactive region 12 is a region sandwiched between internal electrodes 30 having the same polarity. Specifically, among the electrodes 31 and 33 connected to the same external electrode 40 (41), the inactive region 12 includes a portion where the electrode 32 is not located and a portion connected to the same external electrode 40 (42). This is a portion between the electrodes 32 and 34 where the electrode 33 is not positioned.
  • the active portion of the internal electrode 30 located in the active region 11 is the first portion 36 .
  • the inactive portion of the internal electrode 30 located in the inactive region 12 has a second portion 37 having a higher Pd content than the first portion 36 .
  • the first portion 36 has a higher Ag content than the second portion 37 .
  • the contents of Ag and Pd are measured by EPMA (electron probe microanalyzer) after confirming the measurement points by SEM (scanning electron microscope) observation.
  • the content of the first portion 36 is, for example, 70 to 95% by mass of Ag and 5 to 30% by mass of Pd
  • the content of the second portion is, for example, 0.5 to 15% by mass of Ag.
  • Pd is 85 to 99.5% by mass.
  • the piezoelectric element 1 is excellent in durability.
  • Pd is less deformable than, for example, Ag or the like that constitutes the internal electrode 30 . Since the second portion 37 has a higher Pd content than the first portion 36, the inactive region 12 is less likely to deform. Thereby, the piezoelectric element 1 is excellent in durability.
  • the second portion 37 having a high Pd content may be formed into a three-dimensional mesh structure so that the internal electrode 30 itself has a stress relaxation function, or glass having a strong bonding force with the piezoelectric body 20 may be formed in the space of the three-dimensional mesh. Layers and the like may be included. As a result, microcracks are less likely to occur between the second portion 37 and the piezoelectric body 20 even after long-term use, so that the piezoelectric element 1 is further excellent in durability. Note that the second portion 37 does not have to be located in the entire inactive region 12 .
  • the piezoelectric element 1 When the piezoelectric element 1 is used as a piezoelectric sensor, the stress applied to the piezoelectric element 1 also deforms the piezoelectric body 20 in the portion of the inactive region 12 that is in contact with the active region 11 . At this time, since the first portion 36 contains more Ag, which is more easily deformed than Pd or the like, the piezoelectric element 1 can follow the deformation, and thus the piezoelectric element 1 has high durability.
  • the piezoelectric element 1 includes a laminate 10 in which a plurality of piezoelectric bodies 20 and internal electrodes 30 are alternately laminated.
  • the laminate 10 has a square prism shape, it has a length of 2 mm to 10 mm, a width of 2 mm to 10 mm, and a height of 1 mm to 20 mm in the stacking direction.
  • the laminate 10 may have, for example, a hexagonal prism shape, an octagonal prism shape, or a cylindrical shape, other than the quadrangular prism shape.
  • a plurality of piezoelectric bodies 20 forming the laminate 10 are made of piezoelectric ceramics.
  • This piezoelectric ceramic has an average particle size of, for example, about 1.6 to 2.8 ⁇ m.
  • Examples of piezoelectric ceramic materials include perovskite oxides such as lead zirconate titanate (PbZrO 3 —PbTiO 3 ), lithium niobate (LiNbO 3 ), and lithium tantalate (LiTaO 3 ).
  • the internal electrodes 30 are mainly composed of metal such as Ag, Ag--Pd, Ag--Pt, and Cu, and are alternately arranged in the stacking direction. A first pole is led out to one side of the laminate 10 and a second pole is led out to the other side.
  • the first portion 36 and the second portion 37 may be printed with pastes having different ratios of Ag and Pd on the piezoelectric body to form a laminated body, which is then fired.
  • a boundary between the first portion 36 and the second portion 37 can be controlled by a printed pattern.
  • a paste containing a large amount of Ag is printed on the positions of the internal electrodes 30 including the first portion 36 and the second portion 37 to form a laminate, and then the laminate is fired once.
  • a second portion 37 containing a large amount of Pd may be formed at the end portion of the internal electrode 30 by using a diffusion phenomenon by printing a Pd paste on the position of the external electrode 40 and baking it. In the case of this method, since the external electrodes are made of Pd, this may be scraped off to form the external electrodes 40 mainly composed of Au, for example.
  • the first portion 36 may be positioned at the boundary between the active portion and the inactive portion. According to such a structure, since the content of Ag is high at the boundary between the active region and the inactive region, the stress applied particularly to the boundary portion between the active region 11 and the inactive region 12 can be reduced. Thereby, the piezoelectric element 1 is excellent in durability.
  • the external electrode 40 may be positioned within the second portion 37 in a side view. 3 and 6 correspond to this example, and according to this configuration, the external electrode 40 does not have an interface with the first portion 36 . Therefore, a triple interface between the external electrode 40, the first portion 36, and the second portion 37 does not occur.
  • the external electrode 40 has a high Au content
  • the first portion 36 has a high Ag content
  • the second portion 37 has a high Pd content
  • these triple interfaces have a component and a content stress may be applied due to the difference in
  • the piezoelectric element 1 is excellent in durability because no triple interface occurs and less stress is applied.
  • FIG. 4 and 5 are cross-sectional views showing examples of piezoelectric elements according to modifications of the embodiment.
  • FIG. 4 is a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 taken along line AA.
  • FIG. 5 is a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 taken along line BB.
  • the piezoelectric element 1 according to the modified example has a connecting portion 35 positioned between the second portion 37 and the external electrode 40 .
  • the connection portion 35 has a thermal conductivity intermediate between that of the second portion 37 and the external electrode 40 .
  • the connection portion 35 contains Au and Pd. contains an alloy of With such a connection portion 35, heat is easily conducted from the second portion 37 to the connection portion 35 and from the connection portion 35 to the external electrode 40, so that the heat generated in the piezoelectric element 1 is easily released to the outside.
  • the connecting portion 35 may be an alloy of Au, Pd and Ag.
  • the content of Au, Pd and Ag may be measured by EPMA after confirming the measurement points by SEM observation.
  • Au is 30-70% by mass
  • Pd is 0.5-20% by mass
  • Ag is 29.5-69.5% by mass.
  • the connecting portion 35 may have a lower Ag and Pd content than the active portion.
  • the content of Ag and Pd may be measured by EPMA after confirming the measurement points by SEM observation. For example, when Ag is 70 to 95% by mass and Pd is 5 to 30% by mass in the active portion, the content of the connection portion 35 may be lower than these. In other words, the connecting portion 35 may contain metal components other than Ag and Pd.
  • a component such as Au contained in the external electrode 40 may be diffused in the connection portion 35 . Further, it may be an alloy of components contained in the external electrode 40 diffused into the connecting portion 35 and Ag and Pd. This makes it difficult for the external electrodes 40 to separate from the internal electrodes 30 .
  • the connecting portion 35 may contain Ag. With such a configuration, heat dissipation can be enhanced.
  • the external electrode 40 may contain Au and Ag as main components.
  • the Au content is 70 to 95.5% by mass
  • the Ag content is 4.5 to 30% by mass.
  • the external electrode 40 may have a first region in contact with the piezoelectric body and a second region exposed to the outside. At this time, the first region may have a higher Ag content than the second region, and the second region may have a higher Au content than the first region.
  • Ag is a component contained in the internal electrode 30 and has excellent heat conduction characteristics, so that heat generated by driving the element for a long period of time can be transferred to the external electrode 40 and dissipated.
  • the corrosion resistance is excellent.
  • FIG. 6 is a plan view showing an example of a piezoelectric element according to a modified example of the embodiment.
  • FIG. 6 is a plan view of the piezoelectric element 1 viewed from the external electrode 40 side. It is a side view in light of FIG.
  • the external electrode 40 may have a third portion 43 containing Ag.
  • the third portion 43 may be located wider in the thickness direction (Z-axis direction) of the internal electrode 30 than the central portion along the width direction (Y-axis direction) of the internal electrode 30 .
  • being widely positioned means that the length in the Z-axis direction is long.
  • the outer edge side of the external electrode 40 has high heat dissipation, and the central portion has excellent electrical conductivity.
  • 7 and 8 are cross-sectional views showing examples of piezoelectric elements according to modifications of the embodiment. 7 and 8 are other examples of the piezoelectric element 1 shown in FIG. 1 taken along the AA arrow cross section.
  • the external electrode 40 has a layer 50 (first layer) and a layer 60 (second layer).
  • the layer 50 is a layer containing Ag as a main component and in contact with the piezoelectric body 20 .
  • the layer 60 is a layer containing Au as a main component and exposed to the outside.
  • the term “main component” as used herein refers to a component that accounts for more than 50% of all the components constituting the layers 50 and 60, respectively.
  • the external electrode 40 in the piezoelectric element 1 shown in FIG. 8 has layers 50 and 60 .
  • the layer 50 is in contact with the piezoelectric body 20 and positioned on the inner surface side of the external electrode 40 .
  • the layer 50 has, for example, an Au content of 10 to 40 mass % and an Ag content of 60 to 90 mass %.
  • the layer 60 is separated from the piezoelectric body 20 and positioned on the outer surface side of the external electrode 40 .
  • Layer 60 has a higher Au content than layer 50 .
  • the layer 60 has an Au content of 70 to 95.5 mass % and an Ag content of 4.5 to 30 mass %.
  • the external electrode 40 has the layers 50 and 60 configured as described above, the external electrode 40 and the piezoelectric body 20 have excellent adhesion. Moreover, even if the atmosphere outside the piezoelectric element 1 becomes a hot and humid environment, it can be used stably for a long period of time. Furthermore, in order to establish electrical connection between the piezoelectric element 1 and an external circuit, it can be a general-purpose element that enables wire bonding or other various connections.
  • the layer 60 when the layer 60 covers the layer 50 in contact with the piezoelectric body 20 so as to enclose it, it can be used stably for a long period of time even in a harsher environment.
  • the external electrode 40 having a laminated structure as shown in FIGS. 7 and 8, for example, as the first layer of the external electrode 40, a layer containing mainly Ag is printed on the surface of the laminated body 10 and baked. After depositing 50 , layer 60 may be deposited by printing and firing a layer containing primarily Au on the surface of layer 50 . In the piezoelectric element 1 manufactured in this manner, the second portion 27 can be selectively positioned at the boundary portion with the external electrode 40 among the internal electrodes 30 positioned in the inactive region 12 .
  • FIG. 9 is a perspective view showing an example of the piezoelectric sensor according to the embodiment; 10 is a cross-sectional view of the piezoelectric sensor shown in FIG. 9 taken along the line CC.
  • the piezoelectric sensor 100 includes a piezoelectric element 1 and a case 3 surrounding the piezoelectric element 1.
  • the case 3 includes a protrusion 3A protruding inward from the inner surface 4b of the case body.
  • the end surface 3a of the convex portion 3A is in contact with the end surface 1a of the piezoelectric element 1 and positioned inside the outer periphery of the end surface 1a of the piezoelectric element 1.
  • the piezoelectric element 1 is housed in the internal space of the cylindrical case 3 .
  • the piezoelectric element 1 In order to transmit the pressure applied to the outer surface 4 a of the case 3 to the piezoelectric element 1 , the piezoelectric element 1 is housed while being sandwiched between the upper and lower walls of the case 3 .
  • An outer surface 4a located on the upper side of the case 3 is a surface to which an external force is applied. (end face 1a).
  • An end surface 3a of the convex portion 3A is a surface that transmits an external force to the piezoelectric element 1. As shown in FIG.
  • One end face 1a (upper end face) of the piezoelectric element 1 in the stacking direction is in contact with the end face 3a of the projection 3A, and the other end face 1b (lower end face) is an inner face facing the outer face 5a located on the lower side of the case 3. 5b (the bottom surface of the internal space).
  • the piezoelectric sensor 100 of this embodiment includes lead terminals 7 extending from the inner space of the case 3 to the outside.
  • a lead terminal 7 is electrically connected to the piezoelectric element 1 .
  • a voltage generated by the piezoelectric element 1 is output to the outside through the lead terminal 7 .
  • the piezoelectric sensor 100 of the present embodiment uses the highly durable piezoelectric element 1, so that the piezoelectric sensor 100 is excellent in durability.
  • FIG. 9 is a perspective view showing an example of a piezoelectric sensor 100 including the piezoelectric element 1, and FIG. 10 is a cross-sectional view taken along line CC.
  • the case 3 is made of a metal material such as stainless steel (for example, JIS SUS304 or SUS316L).
  • the case 3 is a container having a space for housing the piezoelectric element 1 therein.
  • the case 3 has a columnar or discoidal appearance, but is not limited thereto.
  • the upper wall (top plate 4) to which the external force is applied is circular, it deforms uniformly when the external force is applied. Therefore, the end face 3a of the projection 3A inside the upper wall contacts the end face 1a of the piezoelectric element 1 without tilting.
  • the shape of the convex portion 3A may be such that it has a flat end face 3a that contacts the end face 1a of the laminate 10 of the piezoelectric element 1 in the lamination direction.
  • the shape of the convex portion 3A may be, for example, a prismatic shape such as a quadrangular prism, a hexagonal prism, an octagonal prism, or a truncated pyramid shape in which the case body side is larger than the end face 3a, or as shown in FIGS. It may be cylindrical or frustoconical.
  • the case 3 has an outer dimension of 4 mm to 20 mm in diameter and 2.5 mm to 25 mm in height, and an internal space of 3.4 mm to 19.8 mm in diameter and 1.3 mm to 24.8 mm in height. .
  • the thickness of the case 3 excluding the convex portion 3A is set to 0.1 mm to 1 mm, for example.
  • the projection 3A has, for example, a diameter of 1.2 mm to 9.8 mm and a thickness of 0.05 mm to 0.5 mm.
  • Such convex portions 3A can be formed, for example, by processing metal using a mold corresponding to these shapes.
  • the case 3 has two parts: a bottom plate 5 as a lower wall, a top plate 4 as an upper wall, and a cap-like lid portion having a cylindrical portion 6 as a side wall.
  • the side surface (outer peripheral surface) of the bottom plate 5 and the lower end portion of the inner surface of the lid portion (cylindrical portion 6) are joined by, for example, welding.
  • the case 3 may have the outer edge of the upper surface of the bottom plate 5 joined to the lower end of the lid.
  • the configuration of Case 3 is not limited to this. Contrary to the examples shown in FIGS.
  • the case 3 is a cup-shaped container having a plate-like lid portion as an upper wall, a cylindrical portion 6 as a side wall, and a bottom plate 5 as a lower wall. It may be composed of two parts.
  • the case 3 has a cap-like lid portion having a top plate 4 as an upper wall and a cylindrical portion as an upper side wall, and a bottom plate 5 as a cylindrical portion as a lower side wall and a lower wall. It may consist of two parts with a cup-shaped container.
  • the case 3 may be composed of three parts: a top plate 4 as an upper wall, a cylindrical portion 6 as a side wall, and a bottom plate 5 as a lower wall.
  • the bottom plate 5 of the case 3 is formed with two through holes 5A.
  • a lead terminal 7 is inserted into each through hole 5A, and an insulating sealing material 8 such as glass or resin is filled between the lead terminal 7 and the inner surface of the through hole 5A.
  • the lead terminal 7 is fixed to (the bottom plate 5 of) the case 3 with a sealing material 8 .
  • the end portion of the lead terminal 7 in the internal space and the external electrode 40 of the piezoelectric element 1 are electrically connected via, for example, a lead wire 9 and a bonding material such as solder. Thereby, the voltage signal generated by the piezoelectric element 1 can be output to the outside through the lead terminal 7 .
  • the lead terminal 7 may be directly bonded to the external electrode 40 of the piezoelectric element 1 with a bonding material without the lead wire 9 interposed therebetween.
  • the stress applied to the connection portion between the external electrode 40 and the lead wire 9 due to expansion and contraction of the piezoelectric element 1 is reduced. can be reduced.
  • a through hole may be provided in the top plate 4 of the case 3 and the lead terminal 7 may be provided so as to extend from the upper surface of the case 3 to the outside.
  • the length of the lead terminals 7 protruding from the outer surface of the case 3 can be set to 1 mm to 10 mm, for example.
  • the lead terminal 7 may be made of a metal wire such as enameled copper wire having a diameter of 0.1 mm to 1.0 mm and a length of 1.5 mm to 25 mm.
  • the lead wire 9 is a wire having a diameter of 0.1 mm to 1.0 mm and a length of 1.0 mm to 5.0 mm made of metal such as copper wire, and is joined to the lead terminal 7 by spot welding or the like.

Abstract

This piezoelectric element comprises a layered body and an external electrode. In the layered body, a plurality of piezoelectric bodies and internal electrodes are laminated. The external electrode is positioned on a side surface of the layered body and is connected to the internal electrodes. The layered body has an active region sandwiched between internal electrodes having different polarities, and an inactive region sandwiched between internal electrodes having the same polarity. The internal electrodes contain Ag and Pd as primary components. An active section of the internal electrodes located in the active region is a first section. An inactive section of the internal electrodes located in the inactive region has a second section with a higher Pd content than the first section. The first section has a higher Ag content than the second section.

Description

圧電素子および圧電センサPiezoelectric elements and piezoelectric sensors
　開示の実施形態は、圧電素子および圧電センサに関する。 The disclosed embodiments relate to piezoelectric elements and piezoelectric sensors.
　従来、圧電体および内部電極を積層させた積層体と、内部電極に接続された外部電極とを有する圧電素子が知られている。 Conventionally, a piezoelectric element is known that has a laminated body in which a piezoelectric body and an internal electrode are laminated, and an external electrode connected to the internal electrode.
特開２０２０－１６７２２５号公報JP 2020-167225 A
　実施形態の一態様に係る圧電素子は、積層体と、外部電極とを備える。積層体は、圧電体と内部電極とが複数積層されている。外部電極は、積層体の側面に位置し、前記内部電極に接続されている。前記積層体は、極性が異なる前記内部電極で挟まれた活性領域と、極性が同一の前記内部電極で挟まれた不活性領域とを有する。前記内部電極は、主成分としてＡｇおよびＰｄを含有する。前記活性領域に位置する前記内部電極の活性部は、第１部分である。前記不活性領域に位置する前記内部電極の不活性部は、前記第１部分よりもＰｄの含有率が高い第２部分を有する。前記第１部分は、前記第２部分よりもＡｇの含有率が高い。 A piezoelectric element according to one aspect of an embodiment includes a laminate and an external electrode. The laminate is formed by laminating a plurality of piezoelectric bodies and internal electrodes. External electrodes are positioned on the side surfaces of the laminate and connected to the internal electrodes. The laminate has an active region sandwiched between the internal electrodes of different polarities and an inactive region sandwiched between the internal electrodes of the same polarity. The internal electrodes contain Ag and Pd as main components. An active portion of the internal electrode located in the active region is a first portion. An inactive portion of the internal electrode positioned in the inactive region has a second portion having a higher Pd content than the first portion. The first portion has a higher Ag content than the second portion.
図１は、実施形態に係る圧電素子の一例を示す断面図である。FIG. 1 is a cross-sectional view showing an example of a piezoelectric element according to an embodiment. 図２は、図１に示す圧電素子のＡ－Ａ矢視断面図である。FIG. 2 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line AA. 図３は、図１に示す圧電素子のＢ－Ｂ矢視断面図である。FIG. 3 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line BB. 図４は、実施形態の変形例に係る圧電素子の一例を示す断面図（その１）である。FIG. 4 is a cross-sectional view (part 1) showing an example of a piezoelectric element according to a modification of the embodiment; 図５は、実施形態の変形例に係る圧電素子の一例を示す断面図（その２）である。FIG. 5 is a cross-sectional view (No. 2) showing an example of a piezoelectric element according to a modification of the embodiment. 図６は、実施形態の変形例に係る圧電素子の一例を示す平面図である。FIG. 6 is a plan view showing an example of a piezoelectric element according to a modified example of the embodiment; 図７は、実施形態の変形例に係る圧電素子の一例を示す断面図（その３）である。FIG. 7 is a cross-sectional view (No. 3) showing an example of a piezoelectric element according to a modification of the embodiment. 図８は、実施形態の変形例に係る圧電素子の一例を示す断面図（その４）である。FIG. 8 is a cross-sectional view (part 4) showing an example of a piezoelectric element according to a modification of the embodiment. 図９は、実施形態に係る圧電センサの一例を示す斜視図である。FIG. 9 is a perspective view showing an example of the piezoelectric sensor according to the embodiment; 図１０は、図９に示す圧電センサのＣ－Ｃ矢視断面図である。10 is a cross-sectional view of the piezoelectric sensor shown in FIG. 9 taken along the line CC.
　以下、添付図面を参照して、本願の開示する圧電素子および圧電センサの実施形態について説明する。なお、以下に示す実施形態により本開示が限定されるものではない。また、図面は模式的なものであり、各要素の寸法の関係、各要素の比率などは、現実と異なる場合があることに留意する必要がある。 Hereinafter, embodiments of the piezoelectric element and piezoelectric sensor disclosed in the present application will be described with reference to the accompanying drawings. It should be noted that the present disclosure is not limited by the embodiments shown below. Also, it should be noted that the drawings are schematic, and the relationship of dimensions of each element, the ratio of each element, and the like may differ from reality.
＜圧電素子＞
　図１は、実施形態に係る圧電素子の一例を示す斜視図である。図２は、図１に示す圧電素子のＡ－Ａ矢視断面図である。図３は、図１に示す圧電素子のＢ－Ｂ矢視断面図である。なお、図２は、図１に示す圧電素子１を、ＺＸ平面に沿って断面視したものに相当する。また、図３は、図１に示す圧電素子１を、内部電極３０を含むようにＸＹ平面に沿って断面視したものに相当する。 <Piezoelectric element>
1 is a perspective view showing an example of a piezoelectric element according to an embodiment; FIG. FIG. 2 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line AA. FIG. 3 is a cross-sectional view of the piezoelectric element shown in FIG. 1 taken along line BB. 2 corresponds to a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 along the ZX plane. 3 corresponds to a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 along the XY plane so as to include the internal electrodes 30. As shown in FIG.
　実施形態に係る圧電素子１は、積層体１０と、外部電極４０とを備える。圧電素子１は、例えば、積層体１０が受ける外力を検知して電圧に変換する圧電センサである。 A piezoelectric element 1 according to the embodiment includes a laminate 10 and an external electrode 40 . The piezoelectric element 1 is, for example, a piezoelectric sensor that detects an external force applied to the laminate 10 and converts it into voltage.
　積層体１０は、圧電体２０と内部電極３０とが複数積層されている。圧電体２０は、例えば、強誘電性を有しているセラミックス材料で構成されている。 The laminate 10 is formed by laminating a plurality of piezoelectric bodies 20 and internal electrodes 30 . The piezoelectric body 20 is made of, for example, a ferroelectric ceramic material.
　内部電極３０は、主成分としてＡｇおよびＰｄを含有する。ここで、「主成分」とは、内部電極３０を構成する各種成分のうち、ＡｇおよびＰｄが他の成分と比較して多く含有されていることをいう。内部電極３０を構成する全成分１００質量％のうち、Ａｇが０．５～９９．５質量％、Ｐｄが０．５～９９．５質量％、かつＡｇとＰｄの合計が７０質量％以上である。また、ここでいう「他の成分」としては、例えば、ガラスである。例えば、ＡｇとＰｄの合計が７０質量％のとき、残り３０質量％がガラスである。一方、ガラスがほとんど無く、Ａｇが９９．５質量％、Ｐｄが０．５質量％の場合、あるいはＡｇが０．５質量％、Ｐｄが９９．５質量％の場合もある。 The internal electrode 30 contains Ag and Pd as main components. Here, the “main component” means that Ag and Pd are contained more than other components among the various components that constitute the internal electrode 30 . 0.5 to 99.5% by mass of Ag, 0.5 to 99.5% by mass of Pd, and a total of 70% by mass or more of Ag and Pd out of 100% by mass of all components constituting the internal electrode 30; be. Moreover, as "another component" here, it is glass, for example. For example, when the total of Ag and Pd is 70% by mass, the remaining 30% by mass is glass. On the other hand, there are cases in which there is almost no glass and 99.5 mass % Ag and 0.5 mass % Pd, or 0.5 mass % Ag and 99.5 mass % Pd.
　また、内部電極３０は、電極３１～電極３４を含む。電極３１～電極３４は、圧電体２０を挟んで順に積層されている。電極３１，３３は、一端が外部電極４０である電極４１に電気的に接続されており、ＸＹ平面に沿ってＸ軸正方向側に延びている。電極３２，３４は、一端が外部電極４０である電極４２に電気的に接続されており、ＸＹ平面に沿ってＸ軸負方向側に延びている。 Also, the internal electrode 30 includes electrodes 31 to 34 . The electrodes 31 to 34 are laminated in order with the piezoelectric body 20 interposed therebetween. The electrodes 31 and 33 are electrically connected to an electrode 41 whose one end is the external electrode 40, and extend in the positive X-axis direction along the XY plane. One end of the electrodes 32 and 34 is electrically connected to an electrode 42, which is the external electrode 40, and extends in the X-axis negative direction along the XY plane.
　外部電極４０は、主成分としてＡｕを含有する。外部電極４０は、例えば、５０質量％を超える、特に９０質量％以上のＡｕまたはＡｕ合金を含有する、いわゆる金電極であってもよい。また、外部電極４０は、Ｐｂ（鉛）を含有してもよい。外部電極４０は、例えば、圧電体２０との界面に位置する外部電極４０がＰｂを含有すると、密着性が高くなる。圧電体２０がＰｂを含有するものであるとき、さらに密着性に優れる。外部電極４０は、積層体１０の側面に位置し、内部電極３０に接続される。外部電極４０は、積層体１０を挟んで互いに向かい合う電極４１，４２を有する。電極４１は、積層体１０のＸ軸負方向側の側面に位置している。電極４２は、積層体１０のＸ軸正方向側の側面に位置している。外部電極４０は、積層体１０の側面に沿って、内部電極３０の積層方向であるＺ軸方向と比較して内部電極３０が積層体１０の外部に露出して延びるＹ軸方向に長い略矩形状を有している。 The external electrode 40 contains Au as a main component. The external electrode 40 may be, for example, a so-called gold electrode containing more than 50% by mass, especially 90% by mass or more of Au or an Au alloy. In addition, the external electrodes 40 may contain Pb (lead). For example, when the external electrode 40 located at the interface with the piezoelectric body 20 contains Pb, the adhesion of the external electrode 40 is enhanced. When the piezoelectric body 20 contains Pb, the adhesion is even better. The external electrodes 40 are positioned on the side surfaces of the laminate 10 and connected to the internal electrodes 30 . The external electrode 40 has electrodes 41 and 42 facing each other with the laminate 10 interposed therebetween. The electrode 41 is located on the side surface of the laminate 10 on the negative side of the X-axis. The electrode 42 is located on the side surface of the laminate 10 on the positive side of the X-axis. The external electrodes 40 are formed along the side surfaces of the multilayer body 10, and are substantially rectangular long in the Y-axis direction, which is the direction in which the internal electrodes 30 are stacked, in the Y-axis direction so that the internal electrodes 30 are exposed to the outside of the multilayer body 10, as compared to the Z-axis direction. have a shape.
　積層体１０は、活性領域１１と、不活性領域１２とを有する。活性領域１１は、極性が異なる内部電極３０で挟まれた領域である。具体的には、活性領域１１は、互いに隣り合う内部電極３０同士が互いに向かい合う部位である。 The laminate 10 has an active region 11 and an inactive region 12 . The active region 11 is a region sandwiched between internal electrodes 30 having different polarities. Specifically, the active region 11 is a portion where the adjacent internal electrodes 30 face each other.
　不活性領域１２は、極性が同一の内部電極３０で挟まれた領域である。具体的には、不活性領域１２は、同じ外部電極４０（４１）に接続されている電極３１，３３間のうち、電極３２が位置しない部位、および、同じ外部電極４０（４２）に接続されている電極３２，３４間のうち、電極３３が位置しない部位である。 The inactive region 12 is a region sandwiched between internal electrodes 30 having the same polarity. Specifically, among the electrodes 31 and 33 connected to the same external electrode 40 (41), the inactive region 12 includes a portion where the electrode 32 is not located and a portion connected to the same external electrode 40 (42). This is a portion between the electrodes 32 and 34 where the electrode 33 is not positioned.
　また、活性領域１１に位置する内部電極３０における活性部は、第１部分３６である。また、不活性領域１２に位置する内部電極３０における不活性部は、第１部分３６よりもＰｄの含有率が高い第２部分３７を有する。第１部分３６は、第２部分３７よりもＡｇの含有率が高い。ＡｇおよびＰｄの含有率は、ＳＥＭ（走査型電子顕微鏡）観察にて測定箇所を確認したうえで、ＥＰＭＡ（電子プローブマイクロアナライザ）にて測定する。第１部分３６の含有率としては、例えば、Ａｇが７０～９５質量％、Ｐｄが５～３０質量％であり、第２部分の含有率としては、例えば、Ａｇが０．５～１５質量％、Ｐｄが８５～９９．５質量％である。 Also, the active portion of the internal electrode 30 located in the active region 11 is the first portion 36 . In addition, the inactive portion of the internal electrode 30 located in the inactive region 12 has a second portion 37 having a higher Pd content than the first portion 36 . The first portion 36 has a higher Ag content than the second portion 37 . The contents of Ag and Pd are measured by EPMA (electron probe microanalyzer) after confirming the measurement points by SEM (scanning electron microscope) observation. The content of the first portion 36 is, for example, 70 to 95% by mass of Ag and 5 to 30% by mass of Pd, and the content of the second portion is, for example, 0.5 to 15% by mass of Ag. , Pd is 85 to 99.5% by mass.
　Ａｇは、例えば内部電極３０を構成するＰｄ等と比較して変形しやすい。第１部分３６が第２部分３７よりもＡｇの含有率が高いことにより、活性領域１１が変形する際に生じる応力を低減できる。これにより、圧電素子１は耐久性に優れる。 Ag is more easily deformed than, for example, Pd or the like that constitutes the internal electrode 30 . Since the first portion 36 has a higher Ag content than the second portion 37, the stress generated when the active region 11 deforms can be reduced. Thereby, the piezoelectric element 1 is excellent in durability.
　Ｐｄは、例えば内部電極３０を構成するＡｇ等と比較して変形しにくい。第２部分３７が第１部分３６よりもＰｄの含有率が高いことにより、不活性領域１２が変形しにくくなる。これにより、圧電素子１は耐久性に優れる。 Pd is less deformable than, for example, Ag or the like that constitutes the internal electrode 30 . Since the second portion 37 has a higher Pd content than the first portion 36, the inactive region 12 is less likely to deform. Thereby, the piezoelectric element 1 is excellent in durability.
　さらには、Ｐｄの含有率が高い第２部分３７を３次元網目構造として、内部電極３０自体に応力緩和機能を持たせたり、３次元網目の空間部に圧電体２０との結合力の強いガラス層などを含有させたりしてもよい。これにより、長期間使用しても第２部分３７と圧電体２０との間にマイクロクラックが生じることが少なくなるため、圧電素子１はさらに耐久性に優れる。なお、第２部分３７は、不活性領域１２の全体に位置しなくてもよい。また、圧電素子１を圧電センサとして用いる場合、圧電素子１に加わる応力によって不活性領域１２のうち活性領域１１に接する部分では圧電体２０も変形する。このとき、第１部分３６が、Ｐｄ等と比較して変形しやすいＡｇが多いことにより、変形へ追従できるため、圧電素子１は高い耐久性を有する。 Furthermore, the second portion 37 having a high Pd content may be formed into a three-dimensional mesh structure so that the internal electrode 30 itself has a stress relaxation function, or glass having a strong bonding force with the piezoelectric body 20 may be formed in the space of the three-dimensional mesh. Layers and the like may be included. As a result, microcracks are less likely to occur between the second portion 37 and the piezoelectric body 20 even after long-term use, so that the piezoelectric element 1 is further excellent in durability. Note that the second portion 37 does not have to be located in the entire inactive region 12 . When the piezoelectric element 1 is used as a piezoelectric sensor, the stress applied to the piezoelectric element 1 also deforms the piezoelectric body 20 in the portion of the inactive region 12 that is in contact with the active region 11 . At this time, since the first portion 36 contains more Ag, which is more easily deformed than Pd or the like, the piezoelectric element 1 can follow the deformation, and thus the piezoelectric element 1 has high durability.
　図２に示すような構造とするには、例えば、次のような方法がある。 There are, for example, the following methods to create the structure shown in FIG.
　圧電素子１は、圧電体２０と内部電極３０とが交互に複数積層された積層体１０を備えている。積層体１０は、例えば、四角柱形状であるとき、縦２ｍｍ～１０ｍｍ、横２ｍｍ～１０ｍｍ、積層方向の高さ１ｍｍ～２０ｍｍ程度である。なお、積層体１０は、四角柱形状以外に、例えば六角柱形状や八角柱形状あるいは円柱形状などであってもよい。 The piezoelectric element 1 includes a laminate 10 in which a plurality of piezoelectric bodies 20 and internal electrodes 30 are alternately laminated. For example, when the laminate 10 has a square prism shape, it has a length of 2 mm to 10 mm, a width of 2 mm to 10 mm, and a height of 1 mm to 20 mm in the stacking direction. Note that the laminate 10 may have, for example, a hexagonal prism shape, an octagonal prism shape, or a cylindrical shape, other than the quadrangular prism shape.
　積層体１０を構成する複数の圧電体２０は圧電セラミックスからなる。この圧電セラミックスは、平均粒径が例えば１．６～２．８μｍ程度である。圧電セラミックスの材料としては、例えば、チタン酸ジルコン酸鉛（ＰｂＺｒＯ３－ＰｂＴｉＯ３）等からなるペロブスカイト型酸化物、ニオブ酸リチウム（ＬｉＮｂＯ３）、タンタル酸リチウム（ＬｉＴａＯ３）などが挙げられる。 A plurality of piezoelectric bodies 20 forming the laminate 10 are made of piezoelectric ceramics. This piezoelectric ceramic has an average particle size of, for example, about 1.6 to 2.8 μm. Examples of piezoelectric ceramic materials include perovskite oxides such as lead zirconate titanate (PbZrO 3 —PbTiO 3 ), lithium niobate (LiNbO 3 ), and lithium tantalate (LiTaO 3 ).
　また、内部電極３０は、例えばＡｇ、Ａｇ－Ｐｄ、Ａｇ－Ｐｔ、Ｃｕなどの金属を主成分とするものであり、積層方向に交互に配置されている。積層体１０の一つの側面に第１の極が導出され、他の側面に第２の極が導出されている。 The internal electrodes 30 are mainly composed of metal such as Ag, Ag--Pd, Ag--Pt, and Cu, and are alternately arranged in the stacking direction. A first pole is led out to one side of the laminate 10 and a second pole is led out to the other side.
　内部電極３０を形成するには、第１部分３６と、第２部分３７とで、それぞれＡｇとＰｄの比率の異なるペーストを圧電体に印刷して積層体を形成した後に焼成すればよい。第１部分３６と第２部分３７との境界は、印刷パターンで制御することができる。また、第１部分３６と第２部分３７とを含む内部電極３０の位置にＡｇを多く含むペーストを印刷して積層体を形成した後に一度焼成を行う。次に、外部電極４０の位置にＰｄペーストを印刷して焼成することで拡散現象を利用して内部電極３０の端部にＰｄを多く含む第２部分３７を形成してもよい。なお、この方法の場合、外部電極はＰｄからなるものであるため、これを削り落として、例えば、Ａｕを主成分とする外部電極４０を形成してもよい。 In order to form the internal electrode 30, the first portion 36 and the second portion 37 may be printed with pastes having different ratios of Ag and Pd on the piezoelectric body to form a laminated body, which is then fired. A boundary between the first portion 36 and the second portion 37 can be controlled by a printed pattern. Also, a paste containing a large amount of Ag is printed on the positions of the internal electrodes 30 including the first portion 36 and the second portion 37 to form a laminate, and then the laminate is fired once. Next, a second portion 37 containing a large amount of Pd may be formed at the end portion of the internal electrode 30 by using a diffusion phenomenon by printing a Pd paste on the position of the external electrode 40 and baking it. In the case of this method, since the external electrodes are made of Pd, this may be scraped off to form the external electrodes 40 mainly composed of Au, for example.
　上記方法以外にも各種方法があるが、いずれの方法を用いてもよい。 There are various methods other than the above method, but any method may be used.
　また、図２、図３に示すように、活性部と不活性部との境界に第１部分３６が位置してもよい。このような構成によれば、活性部と不活性部との境界でＡｇの含有率が高いため、特に活性領域１１と不活性領域１２との境界部分が受ける応力を低減できる。これにより、圧電素子１は耐久性に優れる。 Also, as shown in FIGS. 2 and 3, the first portion 36 may be positioned at the boundary between the active portion and the inactive portion. According to such a structure, since the content of Ag is high at the boundary between the active region and the inactive region, the stress applied particularly to the boundary portion between the active region 11 and the inactive region 12 can be reduced. Thereby, the piezoelectric element 1 is excellent in durability.
　また、外部電極４０は、側面視において第２部分３７内に位置していてもよい。図３および図６がこの例にあたり、この構成によれば、外部電極４０は、第１部分３６との間に界面が生じない。そのため、外部電極４０、第１部分３６、第２部分３７による三重界面が生じない。例えば、外部電極４０においてＡｕの含有率が高く、第１部分３６においてＡｇの含有率が高く、第２部分３７においてＰｄの含有率が高い場合、これらの三重界面には、含有成分および含有量の違いにより応力が掛かる場合がある。しかしながら、上記構成によれば、三重界面が生じず、掛かる応力が少ないため、圧電素子１は耐久性に優れる。 Also, the external electrode 40 may be positioned within the second portion 37 in a side view. 3 and 6 correspond to this example, and according to this configuration, the external electrode 40 does not have an interface with the first portion 36 . Therefore, a triple interface between the external electrode 40, the first portion 36, and the second portion 37 does not occur. For example, when the external electrode 40 has a high Au content, the first portion 36 has a high Ag content, and the second portion 37 has a high Pd content, these triple interfaces have a component and a content stress may be applied due to the difference in However, according to the above configuration, the piezoelectric element 1 is excellent in durability because no triple interface occurs and less stress is applied.
　図４、図５は、実施形態の変形例に係る圧電素子の一例を示す断面図である。図４は、図１に示す圧電素子１のＡ－Ａ矢視断面図である。図５は、図１に示す圧電素子１のＢ－Ｂ矢視断面図である。 4 and 5 are cross-sectional views showing examples of piezoelectric elements according to modifications of the embodiment. FIG. 4 is a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 taken along line AA. FIG. 5 is a cross-sectional view of the piezoelectric element 1 shown in FIG. 1 taken along line BB.
　変形例に係る圧電素子１は、第２部分３７と外部電極４０との間に位置する接続部３５を有している。接続部３５は、熱伝導性が第２部分３７と外部電極４０の中間にあたるものである。例えば、第２部分３７がＡｇとＰｄとを含み、第１部分３６よりもＰｄの含有率が高いものであり、外部電極４０の主成分がＡｕであるとき、接続部３５が、ＡｕおよびＰｄの合金を含有するものである。かかる接続部３５を有することにより、第２部分３７から接続部３５、接続部３５から外部電極４０へと熱が伝わりやすいため、圧電素子１で生じた熱が外部へ逃げやすくなる。 The piezoelectric element 1 according to the modified example has a connecting portion 35 positioned between the second portion 37 and the external electrode 40 . The connection portion 35 has a thermal conductivity intermediate between that of the second portion 37 and the external electrode 40 . For example, when the second portion 37 contains Ag and Pd and has a higher Pd content than the first portion 36, and the main component of the external electrode 40 is Au, the connection portion 35 contains Au and Pd. contains an alloy of With such a connection portion 35, heat is easily conducted from the second portion 37 to the connection portion 35 and from the connection portion 35 to the external electrode 40, so that the heat generated in the piezoelectric element 1 is easily released to the outside.
　また、接続部３５は、Ａｕ、ＰｄおよびＡｇの合金であってもよい。Ａｕ、ＰｄおよびＡｇの含有率は、ＳＥＭ観察にて測定箇所を確認したうえで、ＥＰＭＡにて測定すればよい。例えば、Ａｕが３０～７０質量％、Ｐｄが０．５～２０質量％、Ａｇが２９．５～６９．５質量％である。高強度で熱伝導性が優れた材質で接続部３５を構成することにより、耐久性の優れた圧電素子１とすることができるため、小型化を図ることができる。 Also, the connecting portion 35 may be an alloy of Au, Pd and Ag. The content of Au, Pd and Ag may be measured by EPMA after confirming the measurement points by SEM observation. For example, Au is 30-70% by mass, Pd is 0.5-20% by mass, and Ag is 29.5-69.5% by mass. By configuring the connecting portion 35 with a material having high strength and excellent thermal conductivity, the piezoelectric element 1 having excellent durability can be obtained, so that miniaturization can be achieved.
　また、接続部３５は、活性部よりもＡｇおよびＰｄの含有率が低くてもよい。ＡｇとＰｄの含有率は、ＳＥＭ観察にて測定箇所を確認したうえで、ＥＰＭＡにて測定すればよい。例えば、活性部におけるにおけるＡｇが７０～９５質量％、Ｐｄが５～３０質量％であるとき、接続部３５は、これらより低い含有率であればよい。接続部３５は、ＡｇおよびＰｄ以外の金属成分を含んでいてもよいと言い換えることができる。 Also, the connecting portion 35 may have a lower Ag and Pd content than the active portion. The content of Ag and Pd may be measured by EPMA after confirming the measurement points by SEM observation. For example, when Ag is 70 to 95% by mass and Pd is 5 to 30% by mass in the active portion, the content of the connection portion 35 may be lower than these. In other words, the connecting portion 35 may contain metal components other than Ag and Pd.
　接続部３５には、例えば、外部電極４０に含まれるＡｕなどの成分が拡散していてもよい。さらに、接続部３５に拡散した外部電極４０に含まれる成分と、ＡｇおよびＰｄとの合金であってもよい。これにより、外部電極４０が内部電極３０から剥がれにくくなる。 For example, a component such as Au contained in the external electrode 40 may be diffused in the connection portion 35 . Further, it may be an alloy of components contained in the external electrode 40 diffused into the connecting portion 35 and Ag and Pd. This makes it difficult for the external electrodes 40 to separate from the internal electrodes 30 .
　また、接続部３５は、Ａｇを含有していてもよい。かかる構成により、熱散逸性を高めることができる。 Also, the connecting portion 35 may contain Ag. With such a configuration, heat dissipation can be enhanced.
　また、外部電極４０は、主成分としてＡｕおよびＡｇを含有するものであってもよい。このときの具体例としては、Ａｕの含有率が７０～９５．５質量％であり、Ａｇの含有率が４．５～３０質量％である。外部電極４０は、圧電体に接する第１領域と、外部に露出する第２領域とを有していてもよい。そして、このとき第１領域が第２領域よりもＡｇの含有率が高く、第２領域が第１領域よりもＡｕの含有率が高くてもよい。Ａｇは、内部電極３０に含まれる成分であり熱伝導特性に優れているため、長期間の素子駆動によって生じた熱を外部電極４０に伝えて放散することができる。また、外部に露出している第２領域が第１領域よりもＡｕの含有率が高いことにより、耐食性に優れる。 Also, the external electrode 40 may contain Au and Ag as main components. As a specific example at this time, the Au content is 70 to 95.5% by mass, and the Ag content is 4.5 to 30% by mass. The external electrode 40 may have a first region in contact with the piezoelectric body and a second region exposed to the outside. At this time, the first region may have a higher Ag content than the second region, and the second region may have a higher Au content than the first region. Ag is a component contained in the internal electrode 30 and has excellent heat conduction characteristics, so that heat generated by driving the element for a long period of time can be transferred to the external electrode 40 and dissipated. Moreover, since the second region exposed to the outside has a higher Au content than the first region, the corrosion resistance is excellent.
　図６は、実施形態の変形例に係る圧電素子の一例を示す平面図である。図６は、圧電素子１を外部電極４０側から見た平面図である。図１に照らせば側面図である。 FIG. 6 is a plan view showing an example of a piezoelectric element according to a modified example of the embodiment. FIG. 6 is a plan view of the piezoelectric element 1 viewed from the external electrode 40 side. It is a side view in light of FIG.
　図６に示すように、外部電極４０は、Ａｇを含有する第３部分４３を有していてもよい。そして、第３部分４３は、内部電極３０の幅方向（Ｙ軸方向）に沿う中央部分よりも外縁側の方が、内部電極３０の厚み方向（Ｚ軸方向）に広く位置してもよい。ここで、広く位置しているとは、Ｚ軸方向の長さが長いということである。このように、外部電極４０が第３部分４３を有するときには、外部電極４０の外縁側において熱散逸性が高く、中央部分では電気伝導性に優れる。 As shown in FIG. 6, the external electrode 40 may have a third portion 43 containing Ag. The third portion 43 may be located wider in the thickness direction (Z-axis direction) of the internal electrode 30 than the central portion along the width direction (Y-axis direction) of the internal electrode 30 . Here, being widely positioned means that the length in the Z-axis direction is long. Thus, when the external electrode 40 has the third portion 43, the outer edge side of the external electrode 40 has high heat dissipation, and the central portion has excellent electrical conductivity.
　図７、図８は、実施形態の変形例に係る圧電素子の一例を示す断面図である。図７、図８はいずれも、図１に示す圧電素子１のＡ－Ａ矢視断面における他の例である。 7 and 8 are cross-sectional views showing examples of piezoelectric elements according to modifications of the embodiment. 7 and 8 are other examples of the piezoelectric element 1 shown in FIG. 1 taken along the AA arrow cross section.
　図７に示すように、外部電極４０は、層５０（第１層）、層６０（第２層）を有している。層５０は、主成分としてＡｇを含有し、圧電体２０に接する層である。層６０は、主成分としてＡｕを含有し、外部に露出している層である。ここでいう「主成分」とは、層５０および層６０を構成するそれぞれ全成分のうち５０％を超える成分のことである。 As shown in FIG. 7, the external electrode 40 has a layer 50 (first layer) and a layer 60 (second layer). The layer 50 is a layer containing Ag as a main component and in contact with the piezoelectric body 20 . The layer 60 is a layer containing Au as a main component and exposed to the outside. The term “main component” as used herein refers to a component that accounts for more than 50% of all the components constituting the layers 50 and 60, respectively.
　図８に示す圧電素子１における外部電極４０は、層５０および層６０を有する。層５０は、圧電体２０に接しており、外部電極４０の内面側に位置する。層５０は、例えば、Ａｕの含有率が１０～４０質量％、Ａｇの含有率が６０～９０質量％である。 The external electrode 40 in the piezoelectric element 1 shown in FIG. 8 has layers 50 and 60 . The layer 50 is in contact with the piezoelectric body 20 and positioned on the inner surface side of the external electrode 40 . The layer 50 has, for example, an Au content of 10 to 40 mass % and an Ag content of 60 to 90 mass %.
　層６０は、圧電体２０から離れており、外部電極４０の外面側に位置する。層６０は、層５０よりもＡｕの含有率が高い。具体的には、層６０のＡｕの含有率は、７０～９５．５質量％、Ａｇの含有率は、４．５～３０質量％である。 The layer 60 is separated from the piezoelectric body 20 and positioned on the outer surface side of the external electrode 40 . Layer 60 has a higher Au content than layer 50 . Specifically, the layer 60 has an Au content of 70 to 95.5 mass % and an Ag content of 4.5 to 30 mass %.
　このように外部電極４０が上記構成の層５０，６０を有することにより、外部電極４０と圧電体２０とは、密着性に優れる。また、圧電素子１の外部の雰囲気が高温多湿な環境となっても長期間安定に使用することができる。さらに、圧電素子１と外部回路との導通を取るために、ワイヤボンディングやその他の様々な接続を可能となった汎用的な素子とすることができる。 Since the external electrode 40 has the layers 50 and 60 configured as described above, the external electrode 40 and the piezoelectric body 20 have excellent adhesion. Moreover, even if the atmosphere outside the piezoelectric element 1 becomes a hot and humid environment, it can be used stably for a long period of time. Furthermore, in order to establish electrical connection between the piezoelectric element 1 and an external circuit, it can be a general-purpose element that enables wire bonding or other various connections.
　また、図８に示す圧電素子１では、圧電体２０に接する層５０を囲い込むように層６０が覆っているときには、さらに過酷な環境でも長期間安定に使用することができる。 In addition, in the piezoelectric element 1 shown in FIG. 8, when the layer 60 covers the layer 50 in contact with the piezoelectric body 20 so as to enclose it, it can be used stably for a long period of time even in a harsher environment.
　図７、図８に示すような積層構造を有する外部電極４０は、例えば、外部電極４０の１層目として、積層体１０の表面に主にＡｇを含有する層を印刷して焼成し、層５０を位置させた後、層５０の表面に、主にＡｕを含有する層を印刷して焼成することで層６０を位置させてもよい。このようにして作製された圧電素子１では、不活性領域１２に位置する内部電極３０のうち、外部電極４０との境界部分に選択的に第２部分２７を位置させることができる。 The external electrode 40 having a laminated structure as shown in FIGS. 7 and 8, for example, as the first layer of the external electrode 40, a layer containing mainly Ag is printed on the surface of the laminated body 10 and baked. After depositing 50 , layer 60 may be deposited by printing and firing a layer containing primarily Au on the surface of layer 50 . In the piezoelectric element 1 manufactured in this manner, the second portion 27 can be selectively positioned at the boundary portion with the external electrode 40 among the internal electrodes 30 positioned in the inactive region 12 .
　なお、図７、図８では、外部電極４０が層５０，６０を有する例について説明したが、層５０，６０の間に、層５０，６０とは異なる１または複数の層を有してもよい。 7 and 8, an example in which the external electrode 40 has the layers 50 and 60 has been described. good.
＜圧電センサ＞
　図９は、実施形態に係る圧電センサの一例を示す斜視図である。図１０は、図９に示す圧電センサのＣ－Ｃ矢視断面図である。 <Piezoelectric sensor>
FIG. 9 is a perspective view showing an example of the piezoelectric sensor according to the embodiment; 10 is a cross-sectional view of the piezoelectric sensor shown in FIG. 9 taken along the line CC.
　図９、図１０に示すように、実施形態に係る圧電センサ１００は、圧電素子１と、圧電素子１を取り囲むケース３とを備えている。ケース３は、ケース本体の内面４ｂから内側に突出している凸部３Ａを含んでいる。凸部３Ａの端面３ａは、圧電素子１の端面１ａに当接しているとともに、圧電素子１の端面１ａの外周よりも内側に位置している。 As shown in FIGS. 9 and 10, the piezoelectric sensor 100 according to the embodiment includes a piezoelectric element 1 and a case 3 surrounding the piezoelectric element 1. As shown in FIGS. The case 3 includes a protrusion 3A protruding inward from the inner surface 4b of the case body. The end surface 3a of the convex portion 3A is in contact with the end surface 1a of the piezoelectric element 1 and positioned inside the outer periphery of the end surface 1a of the piezoelectric element 1. As shown in FIG.
　圧電センサ１００に、図９および図１０に示す白抜き矢印のように圧力が加わると、ケース３を介して圧電素子１に圧力がかかる。圧電センサ１００は、圧電素子１に圧力が加わることで発生した電圧を外部へ出力する。この電圧の大きさから圧力の大きさが算出される。 When pressure is applied to the piezoelectric sensor 100 as indicated by the white arrows shown in FIGS. 9 and 10, pressure is applied to the piezoelectric element 1 via the case 3 . The piezoelectric sensor 100 outputs a voltage generated by applying pressure to the piezoelectric element 1 to the outside. The magnitude of the pressure is calculated from the magnitude of this voltage.
　本実施形態の圧電センサ１００においては、円筒状のケース３の内部空間に圧電素子１が収納されている。ケース３の外面４ａに加えられた圧力を圧電素子１に伝えるために、ケース３の上下の壁で圧電素子１が挟まれて収納されている。ケース３の上側に位置する外面４ａは外力が加えられる面であり、それと対向するケース３の内面４ｂ（内部空間の天面）に設けられた凸部３Ａの端面３ａが圧電素子１の上端面（端面１ａ）に当接している。凸部３Ａの端面３ａが圧電素子１に外力を伝える面である。圧電素子１の積層方向の一方の端面１ａ（上端面）に凸部３Ａの端面３ａが当接し、他方の端面１ｂ（下端面）は、ケース３の下側に位置する外面５ａに対向する内面５ｂ（内部空間の底面）に当接している。 In the piezoelectric sensor 100 of this embodiment, the piezoelectric element 1 is housed in the internal space of the cylindrical case 3 . In order to transmit the pressure applied to the outer surface 4 a of the case 3 to the piezoelectric element 1 , the piezoelectric element 1 is housed while being sandwiched between the upper and lower walls of the case 3 . An outer surface 4a located on the upper side of the case 3 is a surface to which an external force is applied. (end face 1a). An end surface 3a of the convex portion 3A is a surface that transmits an external force to the piezoelectric element 1. As shown in FIG. One end face 1a (upper end face) of the piezoelectric element 1 in the stacking direction is in contact with the end face 3a of the projection 3A, and the other end face 1b (lower end face) is an inner face facing the outer face 5a located on the lower side of the case 3. 5b (the bottom surface of the internal space).
　本実施形態の圧電センサ１００は、ケース３の内部空間内から外部へ延びているリード端子７を備えている。リード端子７は圧電素子１と電気的に接続されている。圧電素子１で発生した電圧はリード端子７を介して外部へ出力される。 The piezoelectric sensor 100 of this embodiment includes lead terminals 7 extending from the inner space of the case 3 to the outside. A lead terminal 7 is electrically connected to the piezoelectric element 1 . A voltage generated by the piezoelectric element 1 is output to the outside through the lead terminal 7 .
　本実施形態の圧電センサ１００は、耐久性が高い圧電素子１を用いることで、圧電センサ１００は耐久性に優れる。 The piezoelectric sensor 100 of the present embodiment uses the highly durable piezoelectric element 1, so that the piezoelectric sensor 100 is excellent in durability.
　図９は圧電素子１を備える圧電センサ１００の一例を示す斜視図であり、図１０はＣ－Ｃ矢視断面図である。ケース３は、例えばステンレス鋼（例えば、ＪＩＳ規格のＳＵＳ３０４やＳＵＳ３１６Ｌ）などの金属材料からなる。ケース３は、内部に圧電素子１を収納する空間を有する容器である。図９に示す例では、ケース３は外観が円柱状あるいは円盤状の円筒であるがこれに限られない。円筒の場合は、外力の加わる上側の壁（天板４）が円形であるので外力が加わった際に一様に変形する。そのため、上側の壁の内側にある凸部３Ａの端面３ａが、圧電素子１の端面１ａに対して傾くことなく当接するのでよい。 FIG. 9 is a perspective view showing an example of a piezoelectric sensor 100 including the piezoelectric element 1, and FIG. 10 is a cross-sectional view taken along line CC. The case 3 is made of a metal material such as stainless steel (for example, JIS SUS304 or SUS316L). The case 3 is a container having a space for housing the piezoelectric element 1 therein. In the example shown in FIG. 9, the case 3 has a columnar or discoidal appearance, but is not limited thereto. In the case of a cylinder, since the upper wall (top plate 4) to which the external force is applied is circular, it deforms uniformly when the external force is applied. Therefore, the end face 3a of the projection 3A inside the upper wall contacts the end face 1a of the piezoelectric element 1 without tilting.
　また、凸部３Ａの形状は、圧電素子１の積層体１０の積層方向の端面１ａに当接する平坦な端面３ａを有していればよい。凸部３Ａの形状は、例えば四角柱、六角柱、八角柱等の角柱状であってもよく、端面３ａよりケース本体側の方が大きい角錐台状、あるいは図９、図１０に示すような円柱状または円錐台状であってもよい。ケース３は、例えば、外寸が直径４ｍｍ～２０ｍｍで高さが２．５ｍｍ～２５ｍｍで、内部空間が直径３．４ｍｍ～１９．８ｍｍで高さが１．３ｍｍ～２４．８ｍｍに設定される。凸部３Ａを除くケース３の厚みは、例えば０．１ｍｍ～１ｍｍに設定される。凸部３Ａは、例えば、端面３ａの直径が１．２ｍｍ～９．８ｍｍで、厚みが０．０５ｍｍ～０．５ｍｍに設定される。このような凸部３Ａは、例えば、これらの形状に対応する金型を用いて金属を加工することで形成することができる。 Further, the shape of the convex portion 3A may be such that it has a flat end face 3a that contacts the end face 1a of the laminate 10 of the piezoelectric element 1 in the lamination direction. The shape of the convex portion 3A may be, for example, a prismatic shape such as a quadrangular prism, a hexagonal prism, an octagonal prism, or a truncated pyramid shape in which the case body side is larger than the end face 3a, or as shown in FIGS. It may be cylindrical or frustoconical. For example, the case 3 has an outer dimension of 4 mm to 20 mm in diameter and 2.5 mm to 25 mm in height, and an internal space of 3.4 mm to 19.8 mm in diameter and 1.3 mm to 24.8 mm in height. . The thickness of the case 3 excluding the convex portion 3A is set to 0.1 mm to 1 mm, for example. The projection 3A has, for example, a diameter of 1.2 mm to 9.8 mm and a thickness of 0.05 mm to 0.5 mm. Such convex portions 3A can be formed, for example, by processing metal using a mold corresponding to these shapes.
　ケース３は、図９および図１０に示す例では、下側の壁である底板５と、上側の壁である天板４および側壁である筒部６を有するキャップ状の蓋部との２つの部分で構成されており、底板５の側面（外周面）と蓋部（筒部６）の内面の下端部とが例えば溶接などで接合されたものである。ケース３は、底板５の上面外縁部と蓋部の下端部とが接合されていてもよい。ケース３の構成はこれに限られるものではない。図９および図１０に示す例とは逆に、ケース３は、上側の壁である板状の蓋部と、側壁である筒部６および下側の壁である底板５を有するカップ状の容器との２つの部分で構成されていてもよい。あるいは、ケース３は、上側の壁である天板４および上側の側壁である筒部を有するキャップ状の蓋部と、下側の側壁である筒部および下側の壁である底板５を有するカップ状の容器との２つの部分で構成されていてもよい。さらには、ケース３は、上側の壁である天板４と、側壁である筒部６と、下側の壁である底板５との３つの部分で構成されていてもよい。 In the example shown in FIGS. 9 and 10, the case 3 has two parts: a bottom plate 5 as a lower wall, a top plate 4 as an upper wall, and a cap-like lid portion having a cylindrical portion 6 as a side wall. The side surface (outer peripheral surface) of the bottom plate 5 and the lower end portion of the inner surface of the lid portion (cylindrical portion 6) are joined by, for example, welding. The case 3 may have the outer edge of the upper surface of the bottom plate 5 joined to the lower end of the lid. The configuration of Case 3 is not limited to this. Contrary to the examples shown in FIGS. 9 and 10, the case 3 is a cup-shaped container having a plate-like lid portion as an upper wall, a cylindrical portion 6 as a side wall, and a bottom plate 5 as a lower wall. It may be composed of two parts. Alternatively, the case 3 has a cap-like lid portion having a top plate 4 as an upper wall and a cylindrical portion as an upper side wall, and a bottom plate 5 as a cylindrical portion as a lower side wall and a lower wall. It may consist of two parts with a cup-shaped container. Furthermore, the case 3 may be composed of three parts: a top plate 4 as an upper wall, a cylindrical portion 6 as a side wall, and a bottom plate 5 as a lower wall.
　また、図９および図１０に示す例では、ケース３の底板５には貫通孔５Ａが２つ形成されている。この貫通孔５Ａにそれぞれリード端子７が挿通され、リード端子７と貫通孔５Ａの内面との間には例えばガラスや樹脂などの絶縁性の封止材８が充填されている。リード端子７は封止材８でケース３（の底板５）に固定されている。リード端子７の内部空間内の端部と圧電素子１の外部電極４０とは、例えばリード線９およびはんだなどの接合材を介して電気的に接続されている。これにより、圧電素子１で発生した電圧信号を、リード端子７を介して外部へ出力することができる。リード端子７は圧電素子１の外部電極４０にリード線９を介さずに接合材で直接接合してもよい。リード端子７に比較して柔軟性を有するリード線９を介して外部電極４０とリード端子７とを接続すると、圧電素子１の伸縮によって外部電極４０とリード線９との接続部に加わる応力を低減することができる。また、ケース３の天板４に貫通孔を設けて、リード端子７をケース３の上面から外部へ延びるように設けてもよい。ケース３の外面から突出するリード端子７の長さは、例えば１ｍｍ～１０ｍｍに設定することができる。リード端子７は、例えばエナメル被覆された銅線等の金属からなる直径０．１ｍｍ～１．０ｍｍで長さ１．５ｍｍ～２５ｍｍの線材を用いてもよい。リード線９は、例えば銅線等の金属からなる直径０．１ｍｍ～１．０ｍｍで長さ１．０ｍｍ～５．０ｍｍの線材であり、リード端子７に例えばスポット溶接等によって接合される。 In addition, in the examples shown in FIGS. 9 and 10, the bottom plate 5 of the case 3 is formed with two through holes 5A. A lead terminal 7 is inserted into each through hole 5A, and an insulating sealing material 8 such as glass or resin is filled between the lead terminal 7 and the inner surface of the through hole 5A. The lead terminal 7 is fixed to (the bottom plate 5 of) the case 3 with a sealing material 8 . The end portion of the lead terminal 7 in the internal space and the external electrode 40 of the piezoelectric element 1 are electrically connected via, for example, a lead wire 9 and a bonding material such as solder. Thereby, the voltage signal generated by the piezoelectric element 1 can be output to the outside through the lead terminal 7 . The lead terminal 7 may be directly bonded to the external electrode 40 of the piezoelectric element 1 with a bonding material without the lead wire 9 interposed therebetween. When the external electrode 40 and the lead terminal 7 are connected via the lead wire 9 which is more flexible than the lead terminal 7, the stress applied to the connection portion between the external electrode 40 and the lead wire 9 due to expansion and contraction of the piezoelectric element 1 is reduced. can be reduced. Further, a through hole may be provided in the top plate 4 of the case 3 and the lead terminal 7 may be provided so as to extend from the upper surface of the case 3 to the outside. The length of the lead terminals 7 protruding from the outer surface of the case 3 can be set to 1 mm to 10 mm, for example. The lead terminal 7 may be made of a metal wire such as enameled copper wire having a diameter of 0.1 mm to 1.0 mm and a length of 1.5 mm to 25 mm. The lead wire 9 is a wire having a diameter of 0.1 mm to 1.0 mm and a length of 1.0 mm to 5.0 mm made of metal such as copper wire, and is joined to the lead terminal 7 by spot welding or the like.
　さらなる効果や他の態様は、当業者によって容易に導き出すことができる。このため、本開示のより広範な態様は、以上のように表しかつ記述した特定の詳細および代表的な実施形態に限定されるものではない。したがって、添付の請求の範囲およびその均等物によって定義される総括的な発明の概念の精神または範囲から逸脱することなく、様々な変更が可能である。 Further effects and other aspects can be easily derived by those skilled in the art. Therefore, the broader aspects of the disclosure are not limited to the specific details and representative embodiments so represented and described. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and equivalents thereof.
　　１　圧電素子
　１０　積層体
　１１　活性領域
　１２　不活性領域
　２０　圧電体
　３０　内部電極
　３５　接続部
　３６　第１部分
　３７　第２部分
　４０　外部電極
　４３　第３部分
　５０，６０　層
１００　圧電センサ Reference Signs List 1 piezoelectric element 10 laminate 11 active region 12 inactive region 20 piezoelectric body 30 internal electrode 35 connecting portion 36 first portion 37 second portion 40 external electrode 43 third portion 50, 60 layer 100 piezoelectric sensor

Claims (11)

  1. 　圧電体と内部電極とが複数積層された積層体と、
    　該積層体の側面に位置し、前記内部電極に接続される外部電極と
    　を備え、
    　前記積層体は、
    　極性が異なる前記内部電極で挟まれた活性領域と、
    　極性が同一の前記内部電極で挟まれた不活性領域と
    　を有し、
    　前記内部電極は、主成分としてＡｇおよびＰｄを含有し、
    　前記活性領域に位置する前記内部電極の活性部は、第１部分であり、
    　前記不活性領域に位置する前記内部電極の不活性部は、前記第１部分よりもＰｄの含有率が高い第２部分を有し、
    　前記第１部分は、前記第２部分よりもＡｕの含有率が高い、圧電素子。     a laminated body in which a plurality of piezoelectric bodies and internal electrodes are laminated;
    an external electrode located on a side surface of the laminate and connected to the internal electrode;
    The laminate is
    an active region sandwiched between the internal electrodes having different polarities;
    and an inactive region sandwiched between the internal electrodes having the same polarity,
    The internal electrode contains Ag and Pd as main components,
    an active portion of the internal electrode located in the active region is a first portion;
    the inactive portion of the internal electrode located in the inactive region has a second portion having a higher Pd content than the first portion;
    The piezoelectric element, wherein the first portion has a higher Au content than the second portion.
  2. 　前記活性部と前記不活性部との境界に位置する前記内部電極は、前記不活性部よりもＡｇの含有率が高い
    　請求項１に記載の圧電素子。     2. The piezoelectric element according to claim 1, wherein the internal electrode positioned at the boundary between the active portion and the inactive portion has a higher Ag content than the inactive portion.
  3. 　前記外部電極は、側面視において前記第２部分内に位置している
    　請求項１または２に記載の圧電素子。     The piezoelectric element according to claim 1 or 2, wherein the external electrode is positioned inside the second portion when viewed from the side.
  4. 　前記外部電極は、主成分としてＡｕを含有し、
    　前記不活性部と前記外部電極との間に位置する接続部を有し、
    　前記接続部は、ＡｕおよびＰｄの合金を含有する
    　請求項１～３のいずれか１つに記載の圧電素子。     The external electrode contains Au as a main component,
    a connecting portion positioned between the inactive portion and the external electrode;
    The piezoelectric element according to any one of claims 1 to 3, wherein the connection portion contains an alloy of Au and Pd.
  5. 　前記接続部は、前記活性部よりもＡｇおよびＰｄの含有率が低い
    　請求項４に記載の圧電素子。     5. The piezoelectric element according to claim 4, wherein the connection portion has a lower Ag and Pd content than the active portion.
  6. 　前記不活性部と前記外部電極との間に位置し、Ａｇを含有する部位を有する
    　請求項１～５のいずれか１つに記載の圧電素子。     The piezoelectric element according to any one of claims 1 to 5, comprising a portion containing Ag located between the inactive portion and the external electrode.
  7. 　前記外部電極は、平面視で前記内部電極と重なって位置し、Ａｇを含有する第３部分を有し、前記内部電極の厚み方向に沿う前記第３部分の幅は、前記内部電極の幅方向に沿う中央部分よりも外縁側の方が大きい
    　請求項１～６のいずれか１つに記載の圧電素子。     The external electrode has a third portion that overlaps the internal electrode in plan view and contains Ag, and the width of the third portion along the thickness direction of the internal electrode is the width direction of the internal electrode. The piezoelectric element according to any one of claims 1 to 6, wherein the outer edge side is larger than the central portion along the edge.
  8. 　前記積層体は、Ｐｄを含有し、
    　前記外部電極は、前記積層体との界面にＰｂを含有する
    　請求項１～７のいずれか１つに記載の圧電素子。     The laminate contains Pd,
    The piezoelectric element according to any one of claims 1 to 7, wherein the external electrode contains Pb at the interface with the laminate.
  9. 　前記外部電極は、主成分としてＡｕおよびＡｇを含有し、
    　前記積層体に接する第１領域と、外部に露出する第２領域とを有し、
    　前記第１領域は、前記第２領域よりもＡｇの含有率が高く、
    　前記第２領域は、前記第１領域よりもＡｕの含有率が高い
    　請求項１～８のいずれか１つに記載の圧電素子。     The external electrode contains Au and Ag as main components,
    Having a first region in contact with the laminate and a second region exposed to the outside,
    The first region has a higher Ag content than the second region,
    The piezoelectric element according to any one of claims 1 to 8, wherein the second region has a higher Au content than the first region.
  10. 　前記外部電極は、前記積層体に接する第１層と、外部に露出する第２層とを有し、
    　前記第１層は、主成分としてＡｇを含有し、
    　前記第２層は、主成分としてＡｕを含有する
    　請求項１～８のいずれか１つに記載の圧電素子。     The external electrode has a first layer in contact with the laminate and a second layer exposed to the outside,
    The first layer contains Ag as a main component,
    The piezoelectric element according to any one of claims 1 to 8, wherein the second layer contains Au as a main component.
  11. 　請求項１～１０のいずれか１つに記載の圧電素子を備えた圧電センサ。 A piezoelectric sensor comprising the piezoelectric element according to any one of claims 1 to 10.
PCT/JP2022/016098 2021-03-31 2022-03-30 Piezoelectric element and piezoelectric sensor WO2022210916A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2023511496A JPWO2022210916A1 (en) 2021-03-31 2022-03-30

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2021-062049 2021-03-31
JP2021062049 2021-03-31
JP2021-123458 2021-07-28
JP2021123458 2021-07-28

Publications (1)

Publication Number Publication Date
WO2022210916A1 true WO2022210916A1 (en) 2022-10-06

Family

ID=83459576

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2022/016098 WO2022210916A1 (en) 2021-03-31 2022-03-30 Piezoelectric element and piezoelectric sensor

Country Status (2)

Country Link
JP (1) JPWO2022210916A1 (en)
WO (1) WO2022210916A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008010529A (en) * 2006-06-28 2008-01-17 Kyocera Corp Laminated piezoelectric element
JP2017010998A (en) * 2015-06-17 2017-01-12 株式会社村田製作所 Method of manufacturing laminated ceramic electronic component
JP2017183541A (en) * 2016-03-30 2017-10-05 日本碍子株式会社 Piezoelectric element
JP2020123664A (en) * 2019-01-30 2020-08-13 Tdk株式会社 Laminated piezoelectric element

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008010529A (en) * 2006-06-28 2008-01-17 Kyocera Corp Laminated piezoelectric element
JP2017010998A (en) * 2015-06-17 2017-01-12 株式会社村田製作所 Method of manufacturing laminated ceramic electronic component
JP2017183541A (en) * 2016-03-30 2017-10-05 日本碍子株式会社 Piezoelectric element
JP2020123664A (en) * 2019-01-30 2020-08-13 Tdk株式会社 Laminated piezoelectric element

Also Published As

Publication number Publication date
JPWO2022210916A1 (en) 2022-10-06

Similar Documents

Publication Publication Date Title
US5153477A (en) Laminate displacement device
US6316863B1 (en) Piezo actuator with novel contacting and production method
RU2178222C2 (en) Actuating piezoid with new type of contact and its manufacturing process
JP2692396B2 (en) Piezoelectric actuator and manufacturing method thereof
WO2022210916A1 (en) Piezoelectric element and piezoelectric sensor
WO2012026564A1 (en) Piezoelectric actuator
JP5319195B2 (en) Vibrator
JP6557367B2 (en) Pressure sensor
JP2013211419A (en) Lamination type piezoelectric element and piezoelectric actuator
JPH05218519A (en) Electrostrictive effect element
WO2009125553A1 (en) Laminated piezoelectric actuator
JP6825404B2 (en) Vibration device
JP2019087574A (en) Vibration device
JP6284120B2 (en) Piezoelectric actuator
WO2020153289A1 (en) Piezoelectric element
US10897004B2 (en) Piezoelectric drive device
WO2019130773A1 (en) Vibration device
JP3850163B2 (en) Multilayer piezoelectric actuator and manufacturing method thereof
US11944999B2 (en) Vibration device and piezoelectric element
JP7354264B2 (en) piezoelectric actuator
JP2001189499A (en) Laminating-type piezoelectric actuator and manufacturing method therefor
WO2018061496A1 (en) Piezoelectric power generation device
JP7200796B2 (en) Piezoelectric element
WO2020004269A1 (en) Piezoelectric actuator
JP2019102525A (en) Vibration device

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 22781126

Country of ref document: EP

Kind code of ref document: A1

WWE Wipo information: entry into national phase

Ref document number: 2023511496

Country of ref document: JP

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 22781126

Country of ref document: EP

Kind code of ref document: A1