WO2012173081A1 - Laminated piezoelectric actuator - Google Patents

Laminated piezoelectric actuator Download PDF

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Publication number
WO2012173081A1
WO2012173081A1 PCT/JP2012/064889 JP2012064889W WO2012173081A1 WO 2012173081 A1 WO2012173081 A1 WO 2012173081A1 JP 2012064889 W JP2012064889 W JP 2012064889W WO 2012173081 A1 WO2012173081 A1 WO 2012173081A1
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WIPO (PCT)
Prior art keywords
solder
side surfaces
internal electrode
piezoelectric body
multilayer piezoelectric
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PCT/JP2012/064889
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French (fr)
Japanese (ja)
Inventor
西川雅永
北川幸雄
西村俊雄
▲与▼田直
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株式会社村田製作所
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Priority to JP2013520542A priority Critical patent/JP5585730B2/en
Publication of WO2012173081A1 publication Critical patent/WO2012173081A1/en

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    • 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
    • H10N30/875—Further connection or lead arrangements, e.g. flexible wiring boards, terminal pins
    • 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

Definitions

  • the present invention relates to a multilayer piezoelectric actuator that is driven by applying a voltage to a piezoelectric element.
  • FIG. 1 is a schematic perspective view of a multilayer piezoelectric actuator 200 described in Patent Document 1.
  • the multilayer piezoelectric actuator 200 includes a multilayer piezoelectric body 100 in which piezoelectric ceramic layers 105a to 105j and internal electrodes 100a to 100i are stacked, and external electrodes 101a and 101b.
  • the external electrodes 101a and 101b are provided on the side surfaces of the multilayer piezoelectric body 100 facing each other.
  • One end of each of the internal electrodes 100a, 100c, 100e, 100g, and 100i is connected to the external electrode 101b.
  • the internal electrodes 100a, 100c, 100e, 100g, and 100i extend from the external electrode 101b side toward the external electrode 101a side.
  • One end of each of the internal electrodes 100b, 100d, 100f, and 100h is connected to the external electrode 101a.
  • the internal electrodes 100b, 100d, 100f, and 100h extend from the external electrode 101a side toward the external electrode 101b side.
  • the outer electrodes 101a and 101b are provided with frame-like solder adhesion preventing members 102a and 102b, respectively.
  • Lead wires 103 for applying a voltage to the external electrodes 101a and 101b are joined by solder 104 within the frame of the solder adhesion preventing members 102a and 102b.
  • the stacked piezoelectric body 100 is polarized in the stacking direction of the piezoelectric ceramic layers 105a to 105j and the internal electrodes 100a to 100i. For this reason, in the multilayer piezoelectric actuator 200, when the voltage is applied from the lead wire 103, the multilayer piezoelectric body 100 expands and contracts in the stacking direction. The multilayer piezoelectric actuator 200 uses this expansion and contraction to move the axis in the axial direction so as to move the lens.
  • the multilayer piezoelectric actuator 200 when the solder 104 is applied by the solder adhesion preventing members 102a and 102b, the area around the area where the solder 104 is applied on the external electrodes 101a and 101b, or the external electrode of the multilayer piezoelectric body 100 It is possible to prevent solder from adhering to a surface other than the side surface on which 101a and 101b are formed.
  • Patent Document 2 discloses a multilayer piezoelectric actuator provided with a resist region functioning as a solder adhesion preventing member in Patent Document 1.
  • Patent Document 2 by forming a strip-shaped resist region between a soldering region and other regions, it is possible to prevent solder from adhering to regions other than the soldering region when solder is applied. .
  • the multilayer piezoelectric actuators described in Patent Documents 1 and 2 have a problem that delamination may occur between the piezoelectric ceramic layer and the internal electrodes. Such delamination is considered to be caused by a decrease in the adhesion strength between the piezoelectric ceramic layer and the internal electrode due to the stress caused by the shrinkage of the solder during soldering.
  • an object of the present invention is to provide a multilayer piezoelectric actuator capable of suppressing a decrease in adhesion strength between a piezoelectric layer and an internal electrode due to stress caused by shrinkage of a solder that joins a lead wire to the external electrode. Is to provide.
  • the multilayer piezoelectric actuator according to the present invention includes a multilayer piezoelectric body and an external electrode.
  • a multilayer piezoelectric body is formed by alternately laminating a plurality of piezoelectric layers and a plurality of internal electrodes, and has two parallel side surfaces extending in the stacking direction of the piezoelectric layers and the internal electrodes. The end of the internal electrode is exposed.
  • the external electrode is provided on each of the two side surfaces of the multilayer piezoelectric body, and is connected to the end portions of the internal electrodes exposed on the two side surfaces. Have.
  • the solder stop portion is provided adjacent to the bonding region on each of the two side surfaces of the multilayer piezoelectric body, and at the bonding region side, the end not parallel to the interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body Has a part.
  • the soldering portion is provided adjacent to the bonding region on each of the two side surfaces of the multilayer piezoelectric body, and on the bonding region side, an interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body is provided. It has an end that is not parallel. For this reason, a portion of the solder that is in contact with the solder stop portion is not parallel to the interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body.
  • the interlayer interface is a plane orthogonal to the stacking direction.
  • the end of the soldering portion intersects with the end of the internal electrode exposed on the two side surfaces.
  • the internal electrode is connected only to the first internal electrode connected to only one of the external electrodes provided on each of the two side surfaces of the multilayer piezoelectric body and only to the other external electrode. It is preferable that the first internal electrode and the second internal electrode are alternately stacked via the piezoelectric layers.
  • the end of the solder stop portion extends from one of two parallel sides facing each other on the side surface of the multilayer piezoelectric body to the other.
  • the solder stop can be formed in a desired shape even if the dicing position varies.
  • the soldering portion is provided adjacent to the bonding region on each of the two side surfaces of the multilayer piezoelectric body, and on the bonding region side, the interlayer between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body is provided. It has an end that is not parallel to the interface. For this reason, a portion of the solder that is in contact with the solder stop portion is not parallel to the interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body.
  • FIG. 1 is a schematic perspective view of a multilayer piezoelectric actuator described in Patent Document 1.
  • FIG. The perspective view of the structure of the multilayer piezoelectric actuator which concerns on embodiment.
  • FIG. 2A shows a perspective view of the configuration of the multilayer piezoelectric actuator according to this embodiment
  • FIG. 2B shows a side view.
  • the multilayer piezoelectric actuator 1 shown in FIGS. 2A and 2B includes a multilayer piezoelectric body 2.
  • the multilayer piezoelectric body 2 is formed by alternately stacking piezoelectric ceramic layers 21 and internal electrodes 22.
  • the piezoelectric ceramic layer 21 is a piezoelectric layer.
  • the piezoelectric ceramic layer 21 is polarized in the stacking direction of the piezoelectric ceramic layer 21 and the internal electrode 22. That is, the polarization direction of the piezoelectric ceramic layer 21 is parallel to the stacking direction of the piezoelectric ceramic layer 21 and the internal electrode 22.
  • the stacked piezoelectric body 2 is long in the stacking direction and has a rectangular parallelepiped shape.
  • two opposing parallel surfaces are defined as side surfaces of the stacked piezoelectric body 2, and the other two parallel surfaces facing each other are the front and back surfaces of the stacked piezoelectric body 2.
  • the direction perpendicular to the two side surfaces of the multilayer piezoelectric body 2 is defined as the width direction of the multilayer piezoelectric body 2.
  • the multilayer piezoelectric actuator 1 shown in FIGS. 2A and 2B includes external electrodes 31 and 32.
  • the external electrodes 31 and 32 are provided on the two side surfaces of the multilayer piezoelectric body 2, respectively.
  • the external electrodes 31 and 32 are provided for applying a voltage to the piezoelectric ceramic layer 21 via the internal electrode 22 to expand and contract the stacked piezoelectric actuator 1 in the stacking direction.
  • the external electrodes 31 and 32 are made of Ag, Cu, Au, Cr, Ni or an alloy of these metals.
  • the internal electrode 22 of the multilayer piezoelectric body 2 has a plurality of internal electrodes 22a to 22i that are sequentially stacked from the upper side in the stacking direction.
  • the plurality of internal electrodes 22a to 22i are connected to one of the external electrodes 31 and 32. Specifically, the plurality of internal electrodes 22a to 22i has a length in the width direction of the multilayer piezoelectric body 2 (a direction in which the plurality of internal electrodes 22a to 22i extends) is a length between two side surfaces of the multilayer piezoelectric body 2. It has a shorter shape.
  • the plurality of internal electrodes 22a to 22i are either the first internal electrode or the second internal electrode, and the first internal electrode and the second internal electrode are alternately arranged in the stacking direction.
  • Internal electrodes 22a, 22c, 22e, 22g, and 22i are first internal electrodes. One end of each of the internal electrodes 22a, 22c, 22e, 22g, and 22i is connected to the external electrode 31.
  • the internal electrodes 22a, 22c, 22e, 22g, and 22i extend horizontally (perpendicular to the stacking direction) from the external electrode 31 side toward the external electrode 32 side. At this time, the internal electrodes 22a, 22c, 22e, 22g, and 22i are connected to the external electrode 32 because the length in the width direction of the multilayer piezoelectric body 2 is shorter than the length between the two side surfaces of the multilayer piezoelectric body 2. It has not been.
  • the internal electrodes 22b, 22d, 22f, and 22h are second internal electrodes.
  • the internal electrodes 22b, 22d, 22f, and 22h are located between the internal electrodes 22a, 22c, 22e, 22g, and 22i, respectively.
  • One end of each of the internal electrodes 22b, 22d, 22f, and 22h is connected to the external electrode 32.
  • the internal electrodes 22b, 22d, 22f, and 22h extend horizontally (perpendicular to the stacking direction) from the external electrode 32 side toward the external electrode 31 side.
  • the internal electrodes 22b, 22d, 22f, and 22h are not connected to the external electrode 31 because the length in the width direction of the multilayer piezoelectric body 2 is shorter than the length between the two side surfaces of the multilayer piezoelectric body 2. Absent.
  • the ends of the internal electrodes 22 are exposed on the front and back surfaces of the multilayer piezoelectric body 2, and the front and back surfaces are covered with insulating protective films 33 and 34.
  • the insulating protective films 33 and 34 prevent the short circuit between the internal electrodes 22.
  • the insulating protective films 33 and 34 are made of, for example, an insulating resin such as an epoxy resin, and carbon particles are mixed therein. In FIG. 2A, the insulating protective films 33 and 34 are not shown.
  • the piezoelectric ceramic layer which is a piezoelectric layer
  • the piezoelectric ceramic layer has pyroelectricity, so that charges are generated when a temperature change occurs. An electric field is generated by this electric charge.
  • the direction of the generated electric field is opposite to the direction of polarization of the piezoelectric ceramic layer, the degree of polarization of the piezoelectric ceramic layer is lowered, and the piezoelectricity is lowered. It will be. Therefore, the occurrence of such a problem can be prevented by mixing carbon particles in the insulating protective films 33 and 34 and causing the generated charges to flow as a leakage current.
  • the external electrodes 31 and 32 are provided with a solder stop 50.
  • the soldering portion 50 has a shape in which at least a part of the end portion is not parallel to the interlayer interface between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. As shown in FIG. 2B, the end of the solder stop 50 is linear and is inclined with respect to the interlayer interface between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2.
  • a region adjacent to the soldering portion 50 in the vicinity of the upper end in the stacking direction of each of the external electrodes 31 and 32 is a bonding region 4a.
  • Lead wires 40 which are external connection conductors, are joined to the joining regions 4a by solder 41, respectively.
  • a voltage is applied to the external electrodes 31 and 32 by the lead wire 40.
  • the solder stopper 50 prevents the solder from adhering to a region around the bonding region 4 a of each of the external electrodes 31 and 32 or a surface other than the side surface of the multilayer piezoelectric body 2 when the solder 41 is applied. Specifically, the solder stopper 50 prevents the molten solder 41 from flowing out from the joining region 4a.
  • the solder shrinks during soldering, a stress is generated in the direction from the end to the center.
  • the shrinkage stress of the solder increases toward the end of the solder.
  • the solder edge is parallel to the interlayer interface between the piezoelectric ceramic layer and the internal electrode, the solder contraction stress is strongly applied in the stacking direction at the interlayer interface between the piezoelectric ceramic layer and the internal electrode.
  • the adhesion strength between the piezoelectric ceramic layer and the internal electrode is lowered, and the piezoelectric ceramic layer and the internal electrode may be peeled off.
  • the shrinkage stress of the solder is more strongly applied in the stacking direction at the interlayer interface between the piezoelectric ceramic layer and the internal electrode.
  • the internal electrode will be peeled off.
  • the piezoelectric ceramic layer contracts and stress in the direction opposite to the solder shrinkage stress is generated. The possibility that the ceramic layer and the internal electrode peel off is further increased.
  • the portion of the solder 41 that is in contact with the solder stop portion 50 is not parallel to the interlayer interface between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. Stress due to shrinkage of the solder 41 during soldering is not easily applied in the stacking direction at the interlayer interface between the piezoelectric ceramic layer 21 and the internal electrode 22, and the adhesion strength between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. Can be suppressed. Therefore, occurrence of peeling between the piezoelectric ceramic layer 21 and the internal electrode 22 can be prevented.
  • the stress in the direction opposite to the stress due to the shrinkage of the solder 41 during soldering due to the shrinkage of the piezoelectric ceramic layer 21 is possible to prevent the piezoelectric ceramic layer 21 and the internal electrode 22 from peeling off.
  • the solder stopper 50 is made of, for example, an organic resin that is difficult to adhere solder, such as a solder resist.
  • the solder stop 50 is formed by screen printing or ink jet printing.
  • the solder stopper 50 may be made of a metal film having poorer solder wettability than the external electrodes 31 and 32. In this case, it is formed using a photolithography technique.
  • the position and size (length in the stacking direction) of the bonding region 4a and the soldering portion 50 in the external electrodes 31 and 32 are not particularly limited, but the region other than the bonding region 4a in the external electrodes 31 and 32 is better. Larger is preferred.
  • the laminated piezoelectric actuator 1 is incorporated in a device or the like, positioning is performed in a region other than the bonding region 4a in the external electrodes 31 and 32. For this reason, when the area
  • FIGS. 2A and 2B are views showing first to third modified examples of the solder stop portion 50.
  • FIG. 4A, 4B, and 4C are diagrams showing fourth to sixth modifications of the soldering portion 50.
  • FIG. FIG. 5 is a view showing a seventh modification of the soldering portion 50.
  • 3A, FIG. 3B, FIG. 3C, FIG. 4A, FIG. 4B, FIG. 4C and FIG. 5 are side views of the laminated piezoelectric actuator 1 corresponding to FIG. Illustration of 40 and solder 41 is omitted.
  • the soldering portion 50 of the first modification has an end portion on the side of the joining region 4a that has a polygonal line shape, and the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2 It is inclined with respect to the interlayer interface, and has a valley shape that protrudes inside the solder stop 50 in a side view.
  • the end portion of the solder stop portion 50 according to the first modification extends from one of two parallel sides facing each other on the side surface of the multilayer piezoelectric body 2 to the other. Also, as shown in FIG.
  • the soldering portion 50 of the second modification has an end portion on the side of the joining region 4a that has a polygonal line shape, and the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. It is inclined with respect to the interlayer interface, and has a mountain shape that protrudes toward the bonding region 4a in a side view. Further, as shown in FIG. 3C, the soldering portion 50 of the third modification has an end portion on the side of the joining region 4a that has a polygonal line shape, and the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2.
  • solder stop portion 50 of the third modification example extends from one of two parallel sides facing each other on the side surface of the multilayer piezoelectric body 2 to the other.
  • the solder stop 50 can be formed in a desired shape.
  • the soldering portion 50 of the fourth modified example has a curved end at the joining region 4a side and an arc shape that swells to the joining region 4a side view.
  • the soldering portion 50 of the fifth modified example has a curved end at the joining region 4a side and an arc shape recessed inwardly of the soldering portion 50 in a side view. It is.
  • the soldering portion 50 of the sixth modified example has a wavy shape at the end on the bonding region 4a side.
  • the end of the solder stop 50 of the sixth modification extends from one of two parallel sides of the side surface of the multilayer piezoelectric body 2 facing each other to the other.
  • the solder stoppers 50 are formed in a desired shape even if the dicing position varies. can do.
  • soldering stop 50 may be provided so as to surround the joining region 4a.
  • the solder stop portion 50 of the seventh modified example is provided so that two arc-shaped portions sandwich the joining region 4 a from the vertical direction in the stacking direction.
  • the multilayer piezoelectric actuator 1 has been described above, the specific configuration of the multilayer piezoelectric actuator 1 can be appropriately changed in design, and the functions and effects described in the above-described embodiments are the most preferable resulting from the present invention. However, the operations and effects of the present invention are not limited to those described in the above embodiment.
  • 1-layered piezoelectric actuator 2-layered piezoelectric body, 4a-bonding region, 21-piezoelectric ceramic layer, 22, 22a-22i-internal electrode, 31,32-external electrode, 33,34-insulating protective film, 40-lead wire, 41-solder, 50-solder stop

Abstract

A laminated piezoelectric actuator (1) is provided with: a laminated piezoelectric body (2), which has a plurality of piezoelectric layers (21) and a plurality of internal electrodes (22) alternately laminated therein, has two parallel side surfaces extending in the lamination direction of the piezoelectric layers (21) and the internal electrodes (22), and has end portions of the internal electrodes (22) exposed from the two side surfaces; external electrodes (31, 32), each of which is provided on each of the two side surfaces of the laminated piezoelectric body (2), is connected to the internal electrode (22) end portions exposed from each of the two side surfaces, and has a bonding region (4a) where an external connecting conductor (40) is bonded thereto with a solder (41); and solder stopping sections (50), each of which is provided adjacent to each bonding region (4a) on each of the two side surfaces of the laminated piezoelectric body (2), and has, on the bonding region (4a) side, an end portion that is not parallel to each of the interlayer interfaces between each of the piezoelectric layers (21) and each of the internal electrodes (22) in the laminated piezoelectric body (2). Consequently, the laminated piezoelectric actuator, which can suppress deterioration of adhesion strength between the piezoelectric layers and the internal electrodes due to contraction stress of the solder that bonds lead lines to the external electrodes, is provided.

Description

積層型圧電アクチュエータMultilayer piezoelectric actuator
　本発明は、圧電素子に電圧を印加することにより駆動する、積層型圧電アクチュエータに関する。 The present invention relates to a multilayer piezoelectric actuator that is driven by applying a voltage to a piezoelectric element.
　例えば、カメラのオートフォーカス機構において、レンズが取り付けられた軸を軸方向に移動させるために用いられるアクチュエータとして、積層方向に伸縮する積層型圧電アクチュエータがある。（例えば、特許文献１参照）。 For example, in an autofocus mechanism of a camera, there is a stacked piezoelectric actuator that expands and contracts in the stacking direction as an actuator used to move the axis on which the lens is attached in the axial direction. (For example, refer to Patent Document 1).
　図１は、特許文献１に記載の積層型圧電アクチュエータ２００の模式的斜視図である。積層型圧電アクチュエータ２００は、圧電セラミック層１０５ａ～１０５ｊと内部電極１００ａ～１００ｉとが積層された積層型圧電体１００と、外部電極１０１ａ，１０１ｂとを備える。外部電極１０１ａ，１０１ｂは、積層型圧電体１００の互いに対向する側面にそれぞれ設けられている。内部電極１００ａ，１００ｃ，１００ｅ，１００ｇ，１００ｉの一方側の端部は、外部電極１０１ｂに接続されている。内部電極１００ａ，１００ｃ，１００ｅ，１００ｇ，１００ｉは、外部電極１０１ｂ側から外部電極１０１ａ側に向かって延びている。内部電極１００ｂ，１００ｄ，１００ｆ，１００ｈの一方側の端部は、外部電極１０１ａに接続されている。内部電極１００ｂ，１００ｄ，１００ｆ，１００ｈは、外部電極１０１ａ側から外部電極１０１ｂ側に向かって延びている。 FIG. 1 is a schematic perspective view of a multilayer piezoelectric actuator 200 described in Patent Document 1. FIG. The multilayer piezoelectric actuator 200 includes a multilayer piezoelectric body 100 in which piezoelectric ceramic layers 105a to 105j and internal electrodes 100a to 100i are stacked, and external electrodes 101a and 101b. The external electrodes 101a and 101b are provided on the side surfaces of the multilayer piezoelectric body 100 facing each other. One end of each of the internal electrodes 100a, 100c, 100e, 100g, and 100i is connected to the external electrode 101b. The internal electrodes 100a, 100c, 100e, 100g, and 100i extend from the external electrode 101b side toward the external electrode 101a side. One end of each of the internal electrodes 100b, 100d, 100f, and 100h is connected to the external electrode 101a. The internal electrodes 100b, 100d, 100f, and 100h extend from the external electrode 101a side toward the external electrode 101b side.
　さらに、外部電極１０１ａ，１０１ｂには、枠状の半田付着防止部材１０２ａ，１０２ｂがそれぞれ設けられている。半田付着防止部材１０２ａ，１０２ｂの枠内には、外部電極１０１ａ，１０１ｂへ電圧を印加するためのリード線１０３が半田１０４により接合されている。積層型圧電体１００は、圧電セラミック層１０５ａ～１０５ｊと内部電極１００ａ～１００ｉとの積層方向に分極処理されている。このため、積層型圧電アクチュエータ２００では、リード線１０３から電圧が印加されることにより、積層型圧電体１００が積層方向に伸縮する。積層型圧電アクチュエータ２００は、この伸縮を利用して、レンズを動かすように軸を軸方向に移動させる。 Further, the outer electrodes 101a and 101b are provided with frame-like solder adhesion preventing members 102a and 102b, respectively. Lead wires 103 for applying a voltage to the external electrodes 101a and 101b are joined by solder 104 within the frame of the solder adhesion preventing members 102a and 102b. The stacked piezoelectric body 100 is polarized in the stacking direction of the piezoelectric ceramic layers 105a to 105j and the internal electrodes 100a to 100i. For this reason, in the multilayer piezoelectric actuator 200, when the voltage is applied from the lead wire 103, the multilayer piezoelectric body 100 expands and contracts in the stacking direction. The multilayer piezoelectric actuator 200 uses this expansion and contraction to move the axis in the axial direction so as to move the lens.
　一般に、積層型圧電アクチュエータでは、半田の塗布時に、外部電極における半田を塗布する領域の周辺の領域、または積層型圧電体の外部電極が形成されている側面以外の面に半田が付着すると、半田の拘束応力による伸縮量の低下や、絶縁抵抗の劣化等の問題が発生することがある。そこで、積層型圧電アクチュエータ２００では、半田付着防止部材１０２ａ，１０２ｂにより、半田１０４の塗布時に、外部電極１０１ａ，１０１ｂにおける半田１０４を塗布する領域の周辺の領域、または積層型圧電体１００の外部電極１０１ａ，１０１ｂが形成されている側面以外の面に半田が付着することが防止されている。 In general, in a multilayer piezoelectric actuator, when solder is applied, if the solder adheres to the area around the area where the external electrode is coated with solder, or to a surface other than the side surface on which the external electrode of the multilayer piezoelectric body is formed, Problems such as a decrease in the amount of expansion and contraction due to the restraining stress and deterioration of the insulation resistance may occur. Therefore, in the multilayer piezoelectric actuator 200, when the solder 104 is applied by the solder adhesion preventing members 102a and 102b, the area around the area where the solder 104 is applied on the external electrodes 101a and 101b, or the external electrode of the multilayer piezoelectric body 100 It is possible to prevent solder from adhering to a surface other than the side surface on which 101a and 101b are formed.
　また、特許文献２には、特許文献１における半田付着防止部材として機能するレジスト領域が設けられた積層型圧電アクチュエータが開示されている。特許文献２においては、半田付け領域とそれ以外の領域との間に帯状のレジスト領域を形成することで、半田の塗布時に、半田付け領域以外の領域に半田が付着することが防止されている。 Patent Document 2 discloses a multilayer piezoelectric actuator provided with a resist region functioning as a solder adhesion preventing member in Patent Document 1. In Patent Document 2, by forming a strip-shaped resist region between a soldering region and other regions, it is possible to prevent solder from adhering to regions other than the soldering region when solder is applied. .
特開２００７－１５０２００号公報JP 2007-150200 A 特開２００８－６６５６０号公報JP 2008-66560 A
　特許文献１，２に記載の積層型圧電アクチュエータでは、圧電セラミック層と内部電極との層間剥離が生じることがあるといった問題があった。このような層間剥離は、半田付け時における半田の収縮による応力によって、圧電セラミック層と内部電極との間の密着強度が低下しておこるものと考えられる。 The multilayer piezoelectric actuators described in Patent Documents 1 and 2 have a problem that delamination may occur between the piezoelectric ceramic layer and the internal electrodes. Such delamination is considered to be caused by a decrease in the adhesion strength between the piezoelectric ceramic layer and the internal electrode due to the stress caused by the shrinkage of the solder during soldering.
　そこで、本発明の目的は、外部電極にリード線を接合する半田の収縮による応力に起因した、圧電体層と内部電極との間の密着強度の低下を抑制することができる、積層型圧電アクチュエータを提供することにある。 Accordingly, an object of the present invention is to provide a multilayer piezoelectric actuator capable of suppressing a decrease in adhesion strength between a piezoelectric layer and an internal electrode due to stress caused by shrinkage of a solder that joins a lead wire to the external electrode. Is to provide.
　本発明に係る積層型圧電アクチュエータは、積層型圧電体と、外部電極と、とを備える。積層型圧電体は、複数の圧電体層と複数の内部電極とが交互に積層されており、圧電体層と内部電極との積層方向に延びる平行な二つの側面を有し、二つの側面に内部電極の端部が露出している。外部電極は、積層型圧電体の二つの側面のそれぞれに設けられ、二つの側面に露出している内部電極の端部と接続されており、外部接続用導体が半田により接合される接合領域を有する。半田止部は、積層型圧電体の二つの側面のそれぞれに接合領域に隣接して設けられ、接合領域側において、積層型圧電体における圧電体層と内部電極との層間界面と平行とならない端部を有している。 The multilayer piezoelectric actuator according to the present invention includes a multilayer piezoelectric body and an external electrode. A multilayer piezoelectric body is formed by alternately laminating a plurality of piezoelectric layers and a plurality of internal electrodes, and has two parallel side surfaces extending in the stacking direction of the piezoelectric layers and the internal electrodes. The end of the internal electrode is exposed. The external electrode is provided on each of the two side surfaces of the multilayer piezoelectric body, and is connected to the end portions of the internal electrodes exposed on the two side surfaces. Have. The solder stop portion is provided adjacent to the bonding region on each of the two side surfaces of the multilayer piezoelectric body, and at the bonding region side, the end not parallel to the interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body Has a part.
　この構成において、半田止部は、積層型圧電体の二つの側面のそれぞれに接合領域に隣接して設けられ、接合領域側において、積層型圧電体における圧電体層と内部電極との層間界面と平行とならない端部を有している。このため、半田における半田止部と接している部分は、積層型圧電体における圧電体層と内部電極との層間界面と平行にならない。このため、半田付け時の半田の収縮による応力が圧電体層と内部電極との層間界面において積層方向に加わりにくく、積層型圧電体における圧電体層と内部電極との層間の密着強度の低下を抑制することができる。よって、圧電体層と内部電極との剥離の発生を防ぐことができる。なお、層間界面とは、積層方向に直交する平面である。 In this configuration, the soldering portion is provided adjacent to the bonding region on each of the two side surfaces of the multilayer piezoelectric body, and on the bonding region side, an interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body is provided. It has an end that is not parallel. For this reason, a portion of the solder that is in contact with the solder stop portion is not parallel to the interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body. For this reason, stress due to solder shrinkage during soldering is not easily applied in the stacking direction at the interlayer interface between the piezoelectric layer and the internal electrode, which reduces the adhesion strength between the piezoelectric layer and the internal electrode in the stacked piezoelectric body. Can be suppressed. Therefore, occurrence of peeling between the piezoelectric layer and the internal electrode can be prevented. The interlayer interface is a plane orthogonal to the stacking direction.
　本発明に係る積層型圧電アクチュエータにおいて、半田止部の端部は、二つの側面に露出している内部電極の端部と交差していることが好ましい。 In the multilayer piezoelectric actuator according to the present invention, it is preferable that the end of the soldering portion intersects with the end of the internal electrode exposed on the two side surfaces.
　この構成では、圧電体層と内部電極との剥離の発生を防ぐことができる。 In this configuration, it is possible to prevent occurrence of peeling between the piezoelectric layer and the internal electrode.
　本発明に係る積層型圧電アクチュエータにおいて、内部電極は、積層型圧電体の二つの側面のそれぞれに設けられた外部電極の一方にのみ接続された第１内部電極と、外部電極の他方にのみ接続された第２内部電極とを有し、第１内部電極および第２内部電極は、圧電体層を介して交互に積層されていることが好ましい。 In the multilayer piezoelectric actuator according to the present invention, the internal electrode is connected only to the first internal electrode connected to only one of the external electrodes provided on each of the two side surfaces of the multilayer piezoelectric body and only to the other external electrode. It is preferable that the first internal electrode and the second internal electrode are alternately stacked via the piezoelectric layers.
　この構成では、積層型圧電アクチュエータの積層方向に対する伸縮を大きくすることができる。 In this configuration, the expansion and contraction of the stacked piezoelectric actuator in the stacking direction can be increased.
　本発明に係る積層型圧電アクチュエータにおいて、半田止部の端部は、積層型圧電体の側面の互いに対向する平行な２つの辺の一方から他方に至ることが好ましい。 In the multilayer piezoelectric actuator according to the present invention, it is preferable that the end of the solder stop portion extends from one of two parallel sides facing each other on the side surface of the multilayer piezoelectric body to the other.
　この構成では、マザー基板をダイシングして個片化することで積層型圧電アクチュエータを製造する場合に、ダイシングする位置がばらついても半田止部を所望の形状にすることができる。 In this configuration, when the laminated piezoelectric actuator is manufactured by dicing the mother substrate into individual pieces, the solder stop can be formed in a desired shape even if the dicing position varies.
　本発明によれば、半田止部は、積層型圧電体の二つの側面のそれぞれに接合領域に隣接して設けられ、接合領域側において、積層型圧電体における圧電体層と内部電極との層間界面と平行とならない端部を有している。このため、半田における半田止部と接している部分は、積層型圧電体における圧電体層と内部電極との層間界面と平行にならない。このため、半田付け時の半田の収縮による応力が圧電体層と内部電極との層間界面において積層方向に加わりにくく、積層型圧電体における圧電体層と内部電極との層間の密着強度の低下を抑制することができる。よって、圧電体層と内部電極との剥離の発生を防ぐことができる。 According to the present invention, the soldering portion is provided adjacent to the bonding region on each of the two side surfaces of the multilayer piezoelectric body, and on the bonding region side, the interlayer between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body is provided. It has an end that is not parallel to the interface. For this reason, a portion of the solder that is in contact with the solder stop portion is not parallel to the interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body. For this reason, stress due to solder shrinkage during soldering is not easily applied in the stacking direction at the interlayer interface between the piezoelectric layer and the internal electrode, which reduces the adhesion strength between the piezoelectric layer and the internal electrode in the stacked piezoelectric body. Can be suppressed. Therefore, occurrence of peeling between the piezoelectric layer and the internal electrode can be prevented.
特許文献１に記載の積層型圧電アクチュエータの模式的斜視図。1 is a schematic perspective view of a multilayer piezoelectric actuator described in Patent Document 1. FIG. 実施形態に係る積層型圧電アクチュエータの構成の斜視図。The perspective view of the structure of the multilayer piezoelectric actuator which concerns on embodiment. 実施形態に係る積層型圧電アクチュエータの構成の側面視図。The side view of the structure of the laminated piezoelectric actuator which concerns on embodiment. 半田止部の第１の変形例を示す図。The figure which shows the 1st modification of a solder stop | fastening part. 半田止部の第２の変形例を示す図。The figure which shows the 2nd modification of a solder stop | fastening part. 半田止部の第３の変形例を示す図。The figure which shows the 3rd modification of a solder stop | fastening part. 半田止部の第４の変形例を示す図。The figure which shows the 4th modification of a solder stop | fastening part. 半田止部の第５の変形例を示す図。The figure which shows the 5th modification of a solder stop | fastening part. 半田止部の第６の変形例を示す図。The figure which shows the 6th modification of a solder stop | fastening part. 半田止部の第７の変形例を示す図。The figure which shows the 7th modification of a solder stop | fastening part.
　以下、本発明に係る積層型圧電アクチュエータの好適な実施の形態について図面を参照して説明する。 Hereinafter, a preferred embodiment of a multilayer piezoelectric actuator according to the present invention will be described with reference to the drawings.
　図２Ａは本実施形態に係る積層型圧電アクチュエータの構成の斜視図を示し、図２Ｂは側面視図を示す。 FIG. 2A shows a perspective view of the configuration of the multilayer piezoelectric actuator according to this embodiment, and FIG. 2B shows a side view.
　図２Ａおよび図２Ｂに示す積層型圧電アクチュエータ１は、積層型圧電体２を備えている。積層型圧電体２は、圧電セラミック層２１と内部電極２２とが交互に積層されて形成されている。圧電セラミック層２１は、圧電体層である。圧電セラミック層２１は、圧電セラミック層２１と内部電極２２との積層方向に分極されている。すなわち、圧電セラミック層２１の分極方向は、圧電セラミック層２１と内部電極２２との積層方向と平行である。積層型圧電体２は、積層方向に長く、直方体形状を有している。以下では、積層方向に沿った四つの面において、ある対向する平行な二つの面を積層型圧電体２の側面とし、他の対向する平行な二つの面を積層型圧電体２の前面および背面とする。また、積層型圧電体２の二つの側面に直交する方向を、積層型圧電体２の幅方向とする。 The multilayer piezoelectric actuator 1 shown in FIGS. 2A and 2B includes a multilayer piezoelectric body 2. The multilayer piezoelectric body 2 is formed by alternately stacking piezoelectric ceramic layers 21 and internal electrodes 22. The piezoelectric ceramic layer 21 is a piezoelectric layer. The piezoelectric ceramic layer 21 is polarized in the stacking direction of the piezoelectric ceramic layer 21 and the internal electrode 22. That is, the polarization direction of the piezoelectric ceramic layer 21 is parallel to the stacking direction of the piezoelectric ceramic layer 21 and the internal electrode 22. The stacked piezoelectric body 2 is long in the stacking direction and has a rectangular parallelepiped shape. In the following, of the four surfaces along the stacking direction, two opposing parallel surfaces are defined as side surfaces of the stacked piezoelectric body 2, and the other two parallel surfaces facing each other are the front and back surfaces of the stacked piezoelectric body 2. And The direction perpendicular to the two side surfaces of the multilayer piezoelectric body 2 is defined as the width direction of the multilayer piezoelectric body 2.
　図２Ａおよび図２Ｂに示す積層型圧電アクチュエータ１は、外部電極３１，３２を備える。外部電極３１，３２は、積層型圧電体２の二つの側面にそれぞれ設けられている。外部電極３１，３２は、内部電極２２を介して、圧電セラミック層２１に電圧を印加して積層型圧電アクチュエータ１を積層方向に伸縮させるために設けられている。外部電極３１，３２は、Ａｇ、Ｃｕ、Ａｕ、Ｃｒ、Ｎｉあるいはこれらの金属の合金などにより形成されている。また、積層型圧電体２の内部電極２２は、積層方向の上側から順に積層された複数の内部電極２２ａ～２２ｉを有している。複数の内部電極２２ａ～２２ｉは、外部電極３１，３２の何れか一方に接続されている。具体的には、複数の内部電極２２ａ～２２ｉは、積層型圧電体２の幅方向（複数の内部電極２２ａ～２２ｉが延びる方向）の長さが積層型圧電体２の二つの側面間の長さより短い形状を有している。複数の内部電極２２ａ～２２ｉは、第１の内部電極と第２の内部電極のいずれかであり、第１の内部電極と第２の内部電極とは積層方向において交互に配置される。 The multilayer piezoelectric actuator 1 shown in FIGS. 2A and 2B includes external electrodes 31 and 32. The external electrodes 31 and 32 are provided on the two side surfaces of the multilayer piezoelectric body 2, respectively. The external electrodes 31 and 32 are provided for applying a voltage to the piezoelectric ceramic layer 21 via the internal electrode 22 to expand and contract the stacked piezoelectric actuator 1 in the stacking direction. The external electrodes 31 and 32 are made of Ag, Cu, Au, Cr, Ni or an alloy of these metals. The internal electrode 22 of the multilayer piezoelectric body 2 has a plurality of internal electrodes 22a to 22i that are sequentially stacked from the upper side in the stacking direction. The plurality of internal electrodes 22a to 22i are connected to one of the external electrodes 31 and 32. Specifically, the plurality of internal electrodes 22a to 22i has a length in the width direction of the multilayer piezoelectric body 2 (a direction in which the plurality of internal electrodes 22a to 22i extends) is a length between two side surfaces of the multilayer piezoelectric body 2. It has a shorter shape. The plurality of internal electrodes 22a to 22i are either the first internal electrode or the second internal electrode, and the first internal electrode and the second internal electrode are alternately arranged in the stacking direction.
　内部電極２２ａ，２２ｃ，２２ｅ，２２ｇ，２２ｉは、第１内部電極である。内部電極２２ａ，２２ｃ，２２ｅ，２２ｇ，２２ｉの一方側の端部は、外部電極３１に接続されている。内部電極２２ａ，２２ｃ，２２ｅ，２２ｇ，２２ｉは、外部電極３１側から外部電極３２側に向かって水平（積層方向に対して直交方向）に延びている。このとき、内部電極２２ａ，２２ｃ，２２ｅ，２２ｇ，２２ｉは、積層型圧電体２の幅方向の長さが積層型圧電体２の二つの側面間の長さより短いため、外部電極３２とは接続されていない。 Internal electrodes 22a, 22c, 22e, 22g, and 22i are first internal electrodes. One end of each of the internal electrodes 22a, 22c, 22e, 22g, and 22i is connected to the external electrode 31. The internal electrodes 22a, 22c, 22e, 22g, and 22i extend horizontally (perpendicular to the stacking direction) from the external electrode 31 side toward the external electrode 32 side. At this time, the internal electrodes 22a, 22c, 22e, 22g, and 22i are connected to the external electrode 32 because the length in the width direction of the multilayer piezoelectric body 2 is shorter than the length between the two side surfaces of the multilayer piezoelectric body 2. It has not been.
　また、内部電極２２ｂ，２２ｄ，２２ｆ，２２ｈは、第２内部電極である。内部電極２２ｂ，２２ｄ，２２ｆ，２２ｈは、内部電極２２ａ，２２ｃ，２２ｅ，２２ｇ，２２ｉの間にそれぞれ位置する。内部電極２２ｂ，２２ｄ，２２ｆ，２２ｈの一方側の端部は、外部電極３２に接続されている。内部電極２２ｂ，２２ｄ，２２ｆ，２２ｈは、外部電極３２側から外部電極３１側に向かって水平（積層方向に対して直交方向）に延びている。このとき、内部電極２２ｂ，２２ｄ，２２ｆ，２２ｈは、積層型圧電体２の幅方向の長さが積層型圧電体２の二つの側面間の長さより短いため、外部電極３１とは接続されていない。 Further, the internal electrodes 22b, 22d, 22f, and 22h are second internal electrodes. The internal electrodes 22b, 22d, 22f, and 22h are located between the internal electrodes 22a, 22c, 22e, 22g, and 22i, respectively. One end of each of the internal electrodes 22b, 22d, 22f, and 22h is connected to the external electrode 32. The internal electrodes 22b, 22d, 22f, and 22h extend horizontally (perpendicular to the stacking direction) from the external electrode 32 side toward the external electrode 31 side. At this time, the internal electrodes 22b, 22d, 22f, and 22h are not connected to the external electrode 31 because the length in the width direction of the multilayer piezoelectric body 2 is shorter than the length between the two side surfaces of the multilayer piezoelectric body 2. Absent.
　積層型圧電体２の前面および背面に内部電極２２の端部が露出しており、これら前面および背面は絶縁用保護膜３３，３４により覆われている。絶縁用保護膜３３，３４により、内部電極２２間のショートの発生が防止される。絶縁用保護膜３３，３４は、例えば、エポキシ樹脂などの絶縁性樹脂からなり、カーボン粒子が混在されている。なお、図２Ａでは、絶縁用保護膜３３，３４の図示は省略している。 The ends of the internal electrodes 22 are exposed on the front and back surfaces of the multilayer piezoelectric body 2, and the front and back surfaces are covered with insulating protective films 33 and 34. The insulating protective films 33 and 34 prevent the short circuit between the internal electrodes 22. The insulating protective films 33 and 34 are made of, for example, an insulating resin such as an epoxy resin, and carbon particles are mixed therein. In FIG. 2A, the insulating protective films 33 and 34 are not shown.
　絶縁用保護膜を完全な絶縁体とすると、以下のような問題が発生することがある。積層型圧電アクチュエータにおいて、圧電体層である圧電セラミック層は焦電性を有するため、温度変化が発生すると電荷が発生する。この電荷によって電界が発生するが、発生した電界の方向が圧電セラミック層の分極方向と反対側である場合、圧電セラミック層の分極度が低下してしまい、圧電性が低下することになってしまうことになる。そこで、絶縁用保護膜３３，３４にカーボン粒子を混在させ、発生した電荷をリーク電流として流すことで、斯かる問題の発生を防ぐことができる。 If the protective film for insulation is a perfect insulator, the following problems may occur. In the multilayer piezoelectric actuator, the piezoelectric ceramic layer, which is a piezoelectric layer, has pyroelectricity, so that charges are generated when a temperature change occurs. An electric field is generated by this electric charge. However, when the direction of the generated electric field is opposite to the direction of polarization of the piezoelectric ceramic layer, the degree of polarization of the piezoelectric ceramic layer is lowered, and the piezoelectricity is lowered. It will be. Therefore, the occurrence of such a problem can be prevented by mixing carbon particles in the insulating protective films 33 and 34 and causing the generated charges to flow as a leakage current.
　外部電極３１，３２には、半田止部５０が設けられている。半田止部５０は、端部の少なくとも一部が積層型圧電体２における圧電セラミック層２１と内部電極２２との層間界面と平行とならない形状を有している。図２Ｂに示すように、半田止部５０の端部は、直線状であって、積層型圧電体２における圧電セラミック層２１と内部電極２２との層間界面に対して傾斜している。 The external electrodes 31 and 32 are provided with a solder stop 50. The soldering portion 50 has a shape in which at least a part of the end portion is not parallel to the interlayer interface between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. As shown in FIG. 2B, the end of the solder stop 50 is linear and is inclined with respect to the interlayer interface between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2.
　外部電極３１，３２のそれぞれにおける積層方向の上側の端部近傍であって、半田止部５０に隣接する領域は、接合領域４ａである。接合領域４ａには、それぞれ、外部接続用導体であるリード線４０が半田４１により接合されている。リード線４０により、外部電極３１，３２に電圧が印加される。電圧が印加されると、圧電セラミック層２１の分極方向が圧電セラミック層２１と内部電極２２との積層方向と平行であるため、積層型圧電体２が積層方向に伸縮する。半田止部５０は、半田４１の塗布時に、外部電極３１，３２のそれぞれにおける接合領域４ａの周辺の領域、または積層型圧電体２の側面以外の面に半田が付着するのを防止する。具体的には、半田止部５０は、接合領域４ａから溶融した半田４１が流れ出るのを防止する。 A region adjacent to the soldering portion 50 in the vicinity of the upper end in the stacking direction of each of the external electrodes 31 and 32 is a bonding region 4a. Lead wires 40, which are external connection conductors, are joined to the joining regions 4a by solder 41, respectively. A voltage is applied to the external electrodes 31 and 32 by the lead wire 40. When a voltage is applied, since the polarization direction of the piezoelectric ceramic layer 21 is parallel to the stacking direction of the piezoelectric ceramic layer 21 and the internal electrode 22, the stacked piezoelectric body 2 expands and contracts in the stacking direction. The solder stopper 50 prevents the solder from adhering to a region around the bonding region 4 a of each of the external electrodes 31 and 32 or a surface other than the side surface of the multilayer piezoelectric body 2 when the solder 41 is applied. Specifically, the solder stopper 50 prevents the molten solder 41 from flowing out from the joining region 4a.
　一般に、半田付け時に半田が収縮する際、半田では端部から中央部に向かう方向の応力が発生する。この半田の収縮応力は半田の端部側ほど大きくなる。半田の端部が圧電セラミック層と内部電極との層間界面と平行である場合には、半田の収縮応力が圧電セラミック層と内部電極との層間界面において積層方向に強く加わるため、半田の収縮応力によって圧電セラミック層と内部電極との密着強度が低下し、圧電セラミック層と内部電極とが剥離する可能性がある。特に、半田の端部が圧電セラミック層と内部電極との層間界面と同じ位置であると、半田の収縮応力が圧電セラミック層と内部電極との層間界面において積層方向により強く加わるため、圧電セラミック層と内部電極とが剥離する可能性は高くなる。また、外部電極に外部接続用導体が半田により接合された後に、積層型圧電体に再度分極を行う場合、圧電セラミック層の収縮によって半田の収縮応力とは逆方向の応力が発生するため、圧電セラミック層と内部電極とが剥離する可能性はさらに高くなる。 Generally, when the solder shrinks during soldering, a stress is generated in the direction from the end to the center. The shrinkage stress of the solder increases toward the end of the solder. When the solder edge is parallel to the interlayer interface between the piezoelectric ceramic layer and the internal electrode, the solder contraction stress is strongly applied in the stacking direction at the interlayer interface between the piezoelectric ceramic layer and the internal electrode. As a result, the adhesion strength between the piezoelectric ceramic layer and the internal electrode is lowered, and the piezoelectric ceramic layer and the internal electrode may be peeled off. In particular, if the end of the solder is at the same position as the interlayer interface between the piezoelectric ceramic layer and the internal electrode, the shrinkage stress of the solder is more strongly applied in the stacking direction at the interlayer interface between the piezoelectric ceramic layer and the internal electrode. There is a high possibility that the internal electrode will be peeled off. In addition, when the multi-layer piezoelectric body is polarized again after the external connection conductor is joined to the external electrode by soldering, the piezoelectric ceramic layer contracts and stress in the direction opposite to the solder shrinkage stress is generated. The possibility that the ceramic layer and the internal electrode peel off is further increased.
　本実施形態では、半田４１における半田止部５０と接している部分は、積層型圧電体２における圧電セラミック層２１と内部電極２２との層間界面と平行にならない。半田付け時の半田４１の収縮による応力が圧電セラミック層２１と内部電極２２との層間界面において積層方向に加わりにくく、積層型圧電体２における圧電セラミック層２１と内部電極２２との層間の密着強度の低下を抑制することができる。よって、圧電セラミック層２１と内部電極２２との剥離の発生を防ぐことができる。また、リード線４０が半田４１により接合された後に、積層型圧電体２に再度分極を行う場合、圧電セラミック層２１の収縮により、半田付け時の半田４１の収縮による応力とは逆方向の応力が発生しても、本実施形態では圧電セラミック層２１と内部電極２２との剥離の発生を防ぐことができる。 In the present embodiment, the portion of the solder 41 that is in contact with the solder stop portion 50 is not parallel to the interlayer interface between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. Stress due to shrinkage of the solder 41 during soldering is not easily applied in the stacking direction at the interlayer interface between the piezoelectric ceramic layer 21 and the internal electrode 22, and the adhesion strength between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. Can be suppressed. Therefore, occurrence of peeling between the piezoelectric ceramic layer 21 and the internal electrode 22 can be prevented. Further, when the laminated piezoelectric body 2 is polarized again after the lead wire 40 is joined by the solder 41, the stress in the direction opposite to the stress due to the shrinkage of the solder 41 during soldering due to the shrinkage of the piezoelectric ceramic layer 21. Even if this occurs, in the present embodiment, it is possible to prevent the piezoelectric ceramic layer 21 and the internal electrode 22 from peeling off.
　半田止部５０は、例えば、ソルダーレジストなどの半田の付着し難い有機系樹脂からなる。この場合、半田止部５０は、スクリーン印刷やインクジェット印刷で形成される。また、半田止部５０は、外部電極３１，３２より半田の濡れ性が悪い金属膜からなるものであってもよい。この場合、フォトリソグラフィ技術を用いて形成される。 The solder stopper 50 is made of, for example, an organic resin that is difficult to adhere solder, such as a solder resist. In this case, the solder stop 50 is formed by screen printing or ink jet printing. Further, the solder stopper 50 may be made of a metal film having poorer solder wettability than the external electrodes 31 and 32. In this case, it is formed using a photolithography technique.
　なお、外部電極３１，３２における接合領域４ａおよび半田止部５０の位置および大きさ（積層方向における長さ）は、特に限定されないが、外部電極３１，３２における接合領域４ａ以外の領域の方が大きいことが好ましい。積層型圧電アクチュエータ１は、機器などに組み込まれる際、外部電極３１，３２における接合領域４ａ以外の領域内で位置決めが行われる。このため、外部電極３１，３２における接合領域４ａ以外の領域の方が大きいと、位置決めの精度が向上する。 The position and size (length in the stacking direction) of the bonding region 4a and the soldering portion 50 in the external electrodes 31 and 32 are not particularly limited, but the region other than the bonding region 4a in the external electrodes 31 and 32 is better. Larger is preferred. When the laminated piezoelectric actuator 1 is incorporated in a device or the like, positioning is performed in a region other than the bonding region 4a in the external electrodes 31 and 32. For this reason, when the area | region other than the joining area | region 4a in the external electrodes 31 and 32 is larger, the positioning precision will improve.
　また、半田止部５０は、接合領域４ａ側の端部が、図２Ａおよび図２Ｂに示すように直線状でなくてもよく、積層型圧電体２における圧電セラミック層２１と内部電極２２との層間界面と平行とならない形状であれば、適宜変更可能である。図３Ａ、図３Ｂおよび図３Ｃは、半田止部５０の第１～第３の変形例を示す図である。図４Ａ、図４Ｂおよび図４Ｃは、半田止部５０の第４～第６の変形例を示す図である。図５は、半田止部５０の第７の変形例を示す図である。なお、図３Ａ、図３Ｂ、図３Ｃ、図４Ａ、図４Ｂ、図４Ｃおよび図５は、図２Ｂに相当する積層型圧電アクチュエータ１の側面図であり、絶縁用保護膜３３，３４、リード線４０および半田４１の図示は省略している。 Further, the end of the soldering portion 50 on the side of the joining region 4a does not have to be linear as shown in FIGS. 2A and 2B, and the soldering portion 50 is not formed between the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. Any shape that is not parallel to the interlayer interface can be appropriately changed. 3A, 3B, and 3C are views showing first to third modified examples of the solder stop portion 50. FIG. 4A, 4B, and 4C are diagrams showing fourth to sixth modifications of the soldering portion 50. FIG. FIG. 5 is a view showing a seventh modification of the soldering portion 50. 3A, FIG. 3B, FIG. 3C, FIG. 4A, FIG. 4B, FIG. 4C and FIG. 5 are side views of the laminated piezoelectric actuator 1 corresponding to FIG. Illustration of 40 and solder 41 is omitted.
　図３Ａに示すように、第１の変形例の半田止部５０は、接合領域４ａ側の端部が、折れ線状であって、積層型圧電体２における圧電セラミック層２１と内部電極２２との層間界面に対して傾斜しており、側面視で半田止部５０の内側に凸となる谷形状である。第１の変形例の半田止部５０の端部は、積層型圧電体２の側面の互いに対向する平行な２つの辺の一方から他方に至っている。また、図３Ｂに示すように、第２の変形例の半田止部５０は、接合領域４ａ側の端部が、折れ線状であって、積層型圧電体２における圧電セラミック層２１と内部電極２２との層間界面に対して傾斜しており、側面視で接合領域４ａ側に凸となる山形状である。また、図３Ｃに示すように、第３の変形例の半田止部５０は、接合領域４ａ側の端部が、折れ線状であって、積層型圧電体２における圧電セラミック層２１と内部電極２２との層間界面に対して傾斜しており、側面視で山形状と谷形状とに交互になった形状である。第３の変形例の半田止部５０の端部は、積層型圧電体２の側面の互いに対向する平行な２つの辺の一方から他方に至っている。図３Ａに示す第１の変形例と図３Ｃに示す第３の変形例とでは、マザー基板をダイシングして個片化することで積層型圧電アクチュエータ１を製造する場合に、ダイシングする位置がばらついても半田止部５０を所望の形状にすることができる。 As shown in FIG. 3A, the soldering portion 50 of the first modification has an end portion on the side of the joining region 4a that has a polygonal line shape, and the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2 It is inclined with respect to the interlayer interface, and has a valley shape that protrudes inside the solder stop 50 in a side view. The end portion of the solder stop portion 50 according to the first modification extends from one of two parallel sides facing each other on the side surface of the multilayer piezoelectric body 2 to the other. Also, as shown in FIG. 3B, the soldering portion 50 of the second modification has an end portion on the side of the joining region 4a that has a polygonal line shape, and the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. It is inclined with respect to the interlayer interface, and has a mountain shape that protrudes toward the bonding region 4a in a side view. Further, as shown in FIG. 3C, the soldering portion 50 of the third modification has an end portion on the side of the joining region 4a that has a polygonal line shape, and the piezoelectric ceramic layer 21 and the internal electrode 22 in the multilayer piezoelectric body 2. It is the shape which inclined with respect to the interlayer interface, and has a mountain shape and a valley shape alternately in a side view. The end portion of the solder stop portion 50 of the third modification example extends from one of two parallel sides facing each other on the side surface of the multilayer piezoelectric body 2 to the other. In the first modification example shown in FIG. 3A and the third modification example shown in FIG. 3C, when the laminated piezoelectric actuator 1 is manufactured by dicing the mother substrate into pieces, the dicing position varies. However, the solder stop 50 can be formed in a desired shape.
　また、図４Ａに示すように、第４の変形例の半田止部５０は、接合領域４ａ側の端部が、曲線状であって、側面視で接合領域４ａ側に膨らんだ円弧状である。また、図４Ｂに示すように、第５の変形例の半田止部５０は、接合領域４ａ側の端部が、曲線状であって、側面視で半田止部５０の内側に凹んだ円弧状である。また、図４Ｃに示すように、第６の変形例の半田止部５０は、接合領域４ａ側の端部が波線状である。第６の変形例の半田止部５０の端部は、積層型圧電体２の側面の互いに対向する平行な２つの辺の一方から他方に至っている。図４Ｃに示す第６の変形例では、マザー基板をダイシングして個片化することで積層型圧電アクチュエータ１を製造する場合に、ダイシングする位置がばらついても半田止部５０を所望の形状にすることができる。 As shown in FIG. 4A, the soldering portion 50 of the fourth modified example has a curved end at the joining region 4a side and an arc shape that swells to the joining region 4a side view. . As shown in FIG. 4B, the soldering portion 50 of the fifth modified example has a curved end at the joining region 4a side and an arc shape recessed inwardly of the soldering portion 50 in a side view. It is. As shown in FIG. 4C, the soldering portion 50 of the sixth modified example has a wavy shape at the end on the bonding region 4a side. The end of the solder stop 50 of the sixth modification extends from one of two parallel sides of the side surface of the multilayer piezoelectric body 2 facing each other to the other. In the sixth modification shown in FIG. 4C, when the laminated piezoelectric actuator 1 is manufactured by dicing the mother substrate into individual pieces, the solder stoppers 50 are formed in a desired shape even if the dicing position varies. can do.
　さらに、半田止部５０は、接合領域４ａを囲うように設けられていてもよい。例えば、図５に示すように、第７の変形例の半田止部５０は、円弧状の２つの部分が接合領域４ａを積層方向の上下方向から挟むように設けられているものである。 Furthermore, the soldering stop 50 may be provided so as to surround the joining region 4a. For example, as shown in FIG. 5, the solder stop portion 50 of the seventh modified example is provided so that two arc-shaped portions sandwich the joining region 4 a from the vertical direction in the stacking direction.
　以上、積層型圧電アクチュエータ１について説明したが、積層型圧電アクチュエータ１の具体的構成などは、適宜設計変更可能であり、上述の実施形態に記載された作用および効果は、本発明から生じる最も好適な作用および効果を列挙したに過ぎず、本発明による作用および効果は、上述の実施形態に記載されたものに限定されるものではない。 Although the multilayer piezoelectric actuator 1 has been described above, the specific configuration of the multilayer piezoelectric actuator 1 can be appropriately changed in design, and the functions and effects described in the above-described embodiments are the most preferable resulting from the present invention. However, the operations and effects of the present invention are not limited to those described in the above embodiment.
１－積層型圧電アクチュエータ、２－積層型圧電体、４ａ－接合領域、２１－圧電セラミック層、２２，２２ａ～２２ｉ－内部電極、３１，３２－外部電極、３３，３４－絶縁用保護膜、４０－リード線、４１－半田、５０－半田止部 1-layered piezoelectric actuator, 2-layered piezoelectric body, 4a-bonding region, 21-piezoelectric ceramic layer, 22, 22a-22i-internal electrode, 31,32-external electrode, 33,34-insulating protective film, 40-lead wire, 41-solder, 50-solder stop

Claims (4)

  1. 　複数の圧電体層と複数の内部電極とが交互に積層されており、前記圧電体層と前記内部電極との積層方向に延びる平行な二つの側面を有し、前記二つの側面に前記内部電極の端部が露出している積層型圧電体と、
    　前記積層型圧電体の前記二つの側面のそれぞれに設けられ、前記二つの側面に露出している前記内部電極の端部と接続されており、外部接続用導体が半田により接合される接合領域を有する外部電極と、
    　前記積層型圧電体の前記二つの側面のそれぞれに前記接合領域に隣接して設けられ、前記接合領域側において、前記積層型圧電体における前記圧電体層と前記内部電極との層間界面と平行とならない端部を有している半田止部と、
    　を備える、積層型圧電アクチュエータ。     A plurality of piezoelectric layers and a plurality of internal electrodes are alternately stacked, and have two parallel side surfaces extending in the stacking direction of the piezoelectric layers and the internal electrodes, and the internal electrodes are provided on the two side surfaces. A laminated piezoelectric body having exposed end portions of
    A bonding region provided on each of the two side surfaces of the multilayer piezoelectric body, connected to the end portions of the internal electrodes exposed on the two side surfaces, and joined to the external connection conductor by solder. An external electrode having
    Each of the two side surfaces of the multilayer piezoelectric body is provided adjacent to the bonding region, and on the bonding region side, parallel to an interlayer interface between the piezoelectric layer and the internal electrode in the multilayer piezoelectric body. A solder stop having an end that must not be,
    A laminated piezoelectric actuator comprising:
  2. 　前記半田止部の端部は、前記二つの側面に露出している前記内部電極の端部と交差していることを特徴とする請求項１に記載の積層型圧電アクチュエータ。 2. The multilayer piezoelectric actuator according to claim 1, wherein an end portion of the solder stop portion intersects an end portion of the internal electrode exposed on the two side surfaces.
  3. 　前記内部電極は、前記積層型圧電体の二つの側面のそれぞれに設けられた前記外部電極の一方にのみ接続された第１内部電極と、前記外部電極の他方にのみ接続された第２内部電極とを有し、
    　前記第１内部電極および前記第２内部電極は、前記圧電体層を介して交互に積層されていることを特徴とする請求項１または２に記載の積層型圧電アクチュエータ。     The internal electrode includes a first internal electrode connected to only one of the external electrodes provided on each of two side surfaces of the multilayer piezoelectric body, and a second internal electrode connected only to the other of the external electrodes And
    3. The multilayer piezoelectric actuator according to claim 1, wherein the first internal electrode and the second internal electrode are alternately stacked with the piezoelectric layer interposed therebetween.
  4. 　前記半田止部の端部は、前記積層型圧電体の前記側面の互いに対向する平行な２つの辺の一方から他方に至ることを特徴とする請求項１～３のいずれかに記載の積層型圧電アクチュエータ。 The laminated type according to any one of claims 1 to 3, wherein an end portion of the solder stop portion extends from one of two parallel sides of the side surface of the laminated piezoelectric body facing each other to the other. Piezoelectric actuator.
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JPH02266578A (en) * 1989-04-06 1990-10-31 Nec Corp Electrostrictive effect element
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JP2007150200A (en) * 2005-11-30 2007-06-14 Murata Mfg Co Ltd Method of manufacturing electronic component
JP2008066560A (en) * 2006-09-08 2008-03-21 Nec Tokin Corp Laminated piezoelectric actuator

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JPH02266578A (en) * 1989-04-06 1990-10-31 Nec Corp Electrostrictive effect element
JP2005026583A (en) * 2003-07-04 2005-01-27 Shoei Chem Ind Co Ceramic laminated electromechanical sensing element
JP2007150200A (en) * 2005-11-30 2007-06-14 Murata Mfg Co Ltd Method of manufacturing electronic component
JP2008066560A (en) * 2006-09-08 2008-03-21 Nec Tokin Corp Laminated piezoelectric actuator

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021070868A1 (en) * 2019-10-11 2021-04-15 Tdk株式会社 Laminated piezoelectric element

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