JP2016096252A

JP2016096252A - Piezo electric element

Info

Publication number: JP2016096252A
Application number: JP2014231753A
Authority: JP
Inventors: 徳久　泰一; Taiichi Tokuhisa; 泰一徳久
Original assignee: Taiyo Yuden Co Ltd
Current assignee: Taiyo Yuden Co Ltd
Priority date: 2014-11-14
Filing date: 2014-11-14
Publication date: 2016-05-26

Abstract

PROBLEM TO BE SOLVED: To provide a piezo electric element witch enables high density mounting in a good condition.SOLUTION: A piezo electric element comprises: a first external electrode 310 that is formed from one side surface of a piezo electric element main body 200 to a principal surface; and a second external electrode 320 that is formed from the other side surface of the piezo electric element main body 200 to the principal surface, and in the principal surface of piezo electric element main body 200, insulation films 501 and 502 that cover at least one of one or both of the first external electrode 310 and the second external electrode 320 are formed in an opposite region of the first external electrode 310 and the second external electrode 320.SELECTED DRAWING: Figure 1

Description

本発明は、圧電素子に関し、特にその電極構造に関する。 The present invention relates to a piezoelectric element, and more particularly to an electrode structure thereof.

従来、セラミックからなる圧電体層と内部電極とを積層した圧電素子が知られている（特許文献１参照）。特許文献１に記載のものは、内部電極と圧電体層とを積層した圧電素子本体と、圧電素子本体の一方の側面から両主面に亘って形成された第１外部電極と、圧電素子本体の他方の側面に形成された第２外部電極とを備えている。この圧電素子は一対のリード線を第１外部電極及び第２外部電極に半田付けして使用される。ここで、第１外部電極に接続する一方のリード線は、圧電素子本体の主面又は側面の何れかを選択して半田付けできる。第２外部電極に接続する他方のリード線は、圧電素子本体の側面にのみ半田付けできる。 Conventionally, a piezoelectric element in which a piezoelectric layer made of ceramic and an internal electrode are stacked is known (see Patent Document 1). Patent Document 1 discloses a piezoelectric element body in which an internal electrode and a piezoelectric layer are laminated, a first external electrode formed from one side surface to both main surfaces of the piezoelectric element body, and a piezoelectric element body. And a second external electrode formed on the other side surface. This piezoelectric element is used by soldering a pair of lead wires to the first external electrode and the second external electrode. Here, one lead wire connected to the first external electrode can be soldered by selecting either the main surface or the side surface of the piezoelectric element body. The other lead wire connected to the second external electrode can be soldered only to the side surface of the piezoelectric element body.

特開２０１０−１６１２７３号公報JP 2010-161273 A

近年、圧電素子の実装先となる各種電子機器の小型化・高密度化に伴い、圧電素子の実装密度や実装自由度の向上、また実装の容易性などが課題となっている。具体的な要望として、圧電素子本体の側面ではなく表面のみにリード線を半田付けしたいというものがある。このような課題を解決する方策としては、上記従来の圧電素子において圧電素子本体の側面のみに形成された第２外部電極を、圧電素子本体の表面にまで延長して形成することが挙げられる。しかしこの場合、圧電素子本体の表面には既に第１外部電極が形成されているので、第１外部電極と第２外部電極との間のクリアランスが小さくなってしまい、実装の際に電極間が短絡するおそれがある。これを解決するために、圧電素子本体の主面に形成された第１外部電極の形成面積を小さくすることにより電極間のクリアランスを十分に確保する方策が考えられる。しかし、圧電素子本体の主面に形成された第１外部電極は、内部電極との間の圧電効果に資するものである。このため、第１外部電極を小さくすることは変位量の減少を招くおそれがある。さらに第１外部電極と内部電極との間の変位領域と、内部電極間の変位領域が厚み方向で一致しなくなるので、圧電素子本体内に応力が生じ、クラック発生の原因となるおそれもある。さらに、この種の圧電素子は、圧電素子本体の一方の主面にシム板と呼ばれる振動板を付設して用いられることが一般的である。ここで、シム板は金属製の板状部材が用いられることが多い。このため、第１外部電極及び第２外部電極が形成された主面にシム板と呼ばれる振動板を付設した場合、振動板により電極間が短絡するおそれがある。 In recent years, with the reduction in size and increase in density of various electronic devices to which piezoelectric elements are mounted, improvement in mounting density and mounting flexibility of piezoelectric elements, and ease of mounting have become issues. As a specific request, there is a desire to solder a lead wire only to the surface, not the side surface of the piezoelectric element body. As a measure for solving such a problem, there is a method in which the second external electrode formed only on the side surface of the piezoelectric element body in the conventional piezoelectric element is extended to the surface of the piezoelectric element body. However, in this case, since the first external electrode has already been formed on the surface of the piezoelectric element body, the clearance between the first external electrode and the second external electrode is reduced, and the gap between the electrodes during mounting is reduced. There is a risk of short circuit. In order to solve this problem, a method for ensuring a sufficient clearance between the electrodes by reducing the formation area of the first external electrode formed on the main surface of the piezoelectric element body can be considered. However, the first external electrode formed on the main surface of the piezoelectric element body contributes to the piezoelectric effect with the internal electrode. For this reason, reducing the first external electrode may cause a reduction in displacement. Furthermore, since the displacement region between the first external electrode and the internal electrode and the displacement region between the internal electrodes do not coincide with each other in the thickness direction, stress is generated in the piezoelectric element body, which may cause cracks. Furthermore, this type of piezoelectric element is generally used with a diaphragm called a shim plate attached to one main surface of the piezoelectric element body. Here, a metal plate-like member is often used for the shim plate. For this reason, when a diaphragm called a shim plate is attached to the main surface on which the first external electrode and the second external electrode are formed, the electrodes may be short-circuited by the diaphragm.

本発明は、上記事情に鑑みてなされたものであり、その目的とするところは、良好な状態で高密度実装が可能な圧電素子を提供することにある。 The present invention has been made in view of the above circumstances, and an object thereof is to provide a piezoelectric element capable of high-density mounting in a good state.

上記目的を達成するために、本願発明は、圧電体層と一つ又は複数の内部電極とを積層してなる圧電素子本体と、圧電素子本体の一方の側面から主面に亘り形成された第１外部電極と、圧電素子本体の他方の側面から前記主面に亘り形成された第２外部電極とを備え、第１外部電極及び第２外部電極の少なくとも一方又は双方は圧電素子本体の側面において第１外部電極と第２外部電極が短絡しないように内部電極と電気的に接続した圧電素子において、圧電素子本体の主面には第１外部電極及び第２外部電極の対向領域において第１外部電極及び第２外部電極の一方又は双方の少なくとも一部を被覆する絶縁膜が形成されていることを特徴とする。 In order to achieve the above object, the present invention provides a piezoelectric element body formed by laminating a piezoelectric layer and one or a plurality of internal electrodes, and a first element formed from one side surface to the principal surface of the piezoelectric element body. One external electrode and a second external electrode formed from the other side surface of the piezoelectric element body to the main surface, and at least one or both of the first external electrode and the second external electrode are arranged on the side surface of the piezoelectric element body. In the piezoelectric element that is electrically connected to the internal electrode so that the first external electrode and the second external electrode are not short-circuited, the main surface of the piezoelectric element body has a first external electrode in a region facing the first external electrode and the second external electrode. An insulating film covering at least a part of one or both of the electrode and the second external electrode is formed.

本発明によれば、圧電素子本体の主面に第１外部電極と第２外部電極が形成され、且つ、第１外部電極と第２外部電極とが対向する領域に絶縁膜が形成されているので、第１外部電極と第２外部電極の間の絶縁性を十分に確保することができ、結果として実装密度の向上を図ることができる。 According to the present invention, the first external electrode and the second external electrode are formed on the main surface of the piezoelectric element body, and the insulating film is formed in a region where the first external electrode and the second external electrode face each other. Therefore, sufficient insulation between the first external electrode and the second external electrode can be ensured, and as a result, the mounting density can be improved.

本発明の好適な態様の一例としては、圧電素子本体の一方の主面に付設された振動板を備え、前記絶縁膜は圧電素子本体の他方の主面に形成されていることを特徴とするものが挙げられる。本発明によれば、振動板が付設されていない側の圧電素子本体の主面に第１外部電極と第２外部電極が形成されているので、該主面において一対のリード線の双方を半田付けすることができるなど、実装密度の向上や実装の容易性の向上が図れる。また、本発明では、第１外部電極と第２外部電極とが対向する領域に形成された絶縁膜により、第１外部電極の露出領域と第２外部電極の露出領域のクリアランスを十分に確保することができ、これによりリード線の半田付けなどの実装工程を容易に行うことができる。また、本発明では、第１外部電極と第２外部電極のクリアランスを大きく確保する必要がないので、大きな変位領域を確保することができる。 As an example of a preferred aspect of the present invention, a diaphragm attached to one main surface of the piezoelectric element body is provided, and the insulating film is formed on the other main surface of the piezoelectric element body. Things. According to the present invention, since the first external electrode and the second external electrode are formed on the main surface of the piezoelectric element body on the side not provided with the diaphragm, both the pair of lead wires are soldered on the main surface. The mounting density can be improved and the mounting ease can be improved. In the present invention, the insulating film formed in the region where the first external electrode and the second external electrode face each other ensures a sufficient clearance between the exposed region of the first external electrode and the exposed region of the second external electrode. Thus, a mounting process such as soldering of the lead wire can be easily performed. Further, in the present invention, it is not necessary to ensure a large clearance between the first external electrode and the second external electrode, so that a large displacement region can be ensured.

本発明の好適な態様の他の例としては、圧電素子本体の一方の主面に付設された振動板を備え、前記絶縁膜は圧電素子本体の前記一方の主面において第１外部電極及び第２外部電極の一方又は双方の全面を被覆するように形成されていることを特徴とするものが挙げられる。本発明によれば、振動板が導電性を有する場合であっても、振動板を介して第１外部電極と第２外部電極が短絡することを絶縁膜により防止できるので、振動板の実装工程が容易となる。なお絶縁膜は、第１外部電極と第２外部電極の少なくとも一方の全面に形成すれば足りる。この場合、振動板をリード線等の接続端子として機能させることもできる。 As another example of a preferred aspect of the present invention, a diaphragm attached to one main surface of the piezoelectric element body is provided, and the insulating film is formed on the one main surface of the piezoelectric element body with the first external electrode and the first outer electrode. (2) One characterized by being formed so as to cover the entire surface of one or both of the external electrodes. According to the present invention, even if the diaphragm has conductivity, it is possible to prevent the first external electrode and the second external electrode from being short-circuited by the insulating film via the diaphragm. Becomes easy. It is sufficient that the insulating film is formed on the entire surface of at least one of the first external electrode and the second external electrode. In this case, the diaphragm can also function as a connection terminal such as a lead wire.

本発明の好適な態様の他の例としては、圧電素子本体の一方の主面に付設された振動板を備え、前記絶縁膜は圧電素子本体の双方の主面に形成され、且つ、圧電素子本体の一方の主面においては第１外部電極及び第２外部電極の一方又は双方の全面を被覆するように形成されていることを特徴とするものが挙げられる。本発明は、上記２つの態様の作用及び効果を得ることができる。 As another example of a preferred aspect of the present invention, a diaphragm attached to one main surface of the piezoelectric element body is provided, the insulating film is formed on both main surfaces of the piezoelectric element body, and the piezoelectric element One main surface of the main body is characterized by being formed so as to cover the entire surface of one or both of the first external electrode and the second external electrode. The present invention can obtain the operations and effects of the above two aspects.

以上のように本発明によれば、圧電素子本体の主面に第１外部電極と第２外部電極が形成され、且つ、第１外部電極と第２外部電極とが対向する領域に絶縁膜が形成されているので、第１外部電極と第２外部電極の間の絶縁性を十分に確保することができ、結果として実装密度の向上を図ることができる。 As described above, according to the present invention, the first external electrode and the second external electrode are formed on the main surface of the piezoelectric element body, and the insulating film is provided in the region where the first external electrode and the second external electrode face each other. Since it is formed, sufficient insulation between the first external electrode and the second external electrode can be ensured, and as a result, the mounting density can be improved.

第１の実施の形態に係る圧電素子の断面図Sectional drawing of the piezoelectric element which concerns on 1st Embodiment 第１の実施の形態の他の例に係る圧電素子の断面図Sectional drawing of the piezoelectric element which concerns on the other example of 1st Embodiment 第２の実施の形態に係る圧電素子の断面図Sectional drawing of the piezoelectric element which concerns on 2nd Embodiment 第２の実施の形態の他の例に係る圧電素子の断面図Sectional drawing of the piezoelectric element which concerns on the other example of 2nd Embodiment

（第１の実施の形態）
本発明の一実施の形態に係る圧電素子について図面を参照して説明する。図１は圧電素子の断面図である。なお同図は、本発明の特徴を明瞭にすべく模式的に記載したものであり、必ずしも実物とは寸法比等が一致しない点に留意されたい。 (First embodiment)
A piezoelectric element according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a piezoelectric element. It should be noted that this figure is schematically described in order to clarify the features of the present invention, and the dimensional ratio and the like do not necessarily match those of the actual product.

本実施の形態に係る圧電素子１は、図１に示すように、１つの圧電素子１００を、シム板と呼ばれる振動板１０の一方の主面に接着材２０により接着したものである。なお、このような圧電素子１００と振動板１０の組はユニモルフ型の圧電素子と呼ばれる。 As shown in FIG. 1, the piezoelectric element 1 according to the present embodiment is obtained by bonding one piezoelectric element 100 to one main surface of a diaphragm 10 called a shim plate with an adhesive 20. Such a combination of the piezoelectric element 100 and the diaphragm 10 is called a unimorph type piezoelectric element.

圧電素子１００は、略直方体形状の圧電素子本体２００と、圧電素子本体２００の一方の側面から両主面に亘って形成された第１外部電極３１０と、圧電素子本体２００の他方の側面から両主面に亘って形成された第２外部電極３２０とを備えている。 The piezoelectric element 100 includes a piezoelectric element body 200 having a substantially rectangular parallelepiped shape, a first external electrode 310 formed from one side surface of the piezoelectric element body 200 to both main surfaces, and both sides from the other side surface of the piezoelectric element body 200. And a second external electrode 320 formed over the main surface.

圧電素子本体２００は、複数（本実施の形態では２つ）の圧電体層２０５と、一つ又は複数（本実施の形態では１つ）の内部電極２１０とを積層してなる。 The piezoelectric element body 200 is formed by laminating a plurality (two in the present embodiment) of piezoelectric layers 205 and one or a plurality (one in the present embodiment) of internal electrodes 210.

圧電体層２０５は、圧電セラミックなどの適宜の圧電材料により形成されている。本実施の形態では、圧電セラミックを用い、具体的にはＰＺＴ（チタン酸ジルコン酸鉛）系セラミックを用いた。 The piezoelectric layer 205 is made of an appropriate piezoelectric material such as a piezoelectric ceramic. In this embodiment, a piezoelectric ceramic is used, specifically, a PZT (lead zirconate titanate) ceramic.

内部電極２１０は、圧電素子本体２００に複数設けられている場合には、交互に圧電素子本体２００の異なる側面に露出する。圧電素子本体２００に内部電極２１０が１つの場合には、圧電素子本体２００の一方の側面に露出する。内部電極２１０は、圧電素子本体２００の側面において第１外部電極３１０又は第２外部電極３２０と電気的に接続する。本実施の形態では、内部電極２１０は１つであり、第２外部電極３２０が形成されている圧電素子本体２００の側面に露出し、第２外部電極３２０と電気的に接続する。内部電極２１０は、圧電体層２０５を介して対向する他の内部電極２１０、又は、第１外部電極３１０或いは第２外部電極３２０であって圧電素子本体２００の主面に形成された部位と対向し、圧電効果による変位領域を形成する。このため内部電極２１０は、第１外部電極３１０と第２外部電極３２０が短絡しない範囲で大きく形成することが好ましい。内部電極２１０は、Ａｇ、Ｃｕ、Ｓｎ、Ａｕ、Ｎｉ，Ｆｅ、Ｐｄ、Ｐｔ等の金属やこれらの合金により形成される。本実施の形態ではＡｇ−Ｐｄ合金を用いた。 When a plurality of internal electrodes 210 are provided on the piezoelectric element body 200, the internal electrodes 210 are alternately exposed on different side surfaces of the piezoelectric element body 200. When the piezoelectric element body 200 has one internal electrode 210, the piezoelectric element body 200 is exposed on one side surface. The internal electrode 210 is electrically connected to the first external electrode 310 or the second external electrode 320 on the side surface of the piezoelectric element body 200. In the present embodiment, there is one internal electrode 210, which is exposed on the side surface of the piezoelectric element body 200 where the second external electrode 320 is formed, and is electrically connected to the second external electrode 320. The internal electrode 210 is opposed to another internal electrode 210 facing the piezoelectric layer 205, or the first external electrode 310 or the second external electrode 320 which is formed on the main surface of the piezoelectric element body 200. Then, a displacement region due to the piezoelectric effect is formed. For this reason, it is preferable that the internal electrode 210 be formed large so long as the first external electrode 310 and the second external electrode 320 are not short-circuited. The internal electrode 210 is made of a metal such as Ag, Cu, Sn, Au, Ni, Fe, Pd, Pt, or an alloy thereof. In this embodiment, an Ag—Pd alloy is used.

第１外部電極３１０は、圧電素子本体２００の一方の側面の全面に形成された側面部３１１と、振動板１０が付設されていない側の主面側に張り出した第１張出部３１２と、振動板１０が付設されている側の主面側に張り出した第２張出部３１３とを一体に形成してなる。本実施の形態では内部電極２１０が１つのみであるという関係上、側面部３１１は内部電極２１０とは接続されていない。第１張出部３１２及び第２張出部３１３は、圧電体層２０５を介して内部電極２１０と対向し、圧電効果による変位領域を形成する。このため、第１張出部３１２及び第２張出部３１３は、第２外部電極３２０と短絡しない範囲で大きく形成することが好ましい。また、第１張出部３１２及び第２張出部３１３は、内部電極２１０との関係で変位領域が厚み方向で一致すると好ましい。変位領域と非変位領域との界面又はその近傍における応力の発生を軽減し、クラックの発生などを防止するためである。本実施の形態では、第１張出部３１２及び第２張出部３１３を、同一形状とした。第１外部電極３１０は、Ａｇ、Ｃｕ、Ｓｎ、Ａｕ、Ｎｉ，Ｆｅ、Ｐｄ、Ｐｔ等の金属やこれらの合金により形成される。本実施の形態ではＡｇ−Ｐｄ合金を用いた。 The first external electrode 310 includes a side surface portion 311 formed on the entire surface of one side surface of the piezoelectric element body 200, a first overhang portion 312 overhanging on the main surface side where the diaphragm 10 is not provided, A second projecting portion 313 projecting to the main surface side where the diaphragm 10 is attached is integrally formed. In the present embodiment, side surface portion 311 is not connected to internal electrode 210 because there is only one internal electrode 210. The first overhang portion 312 and the second overhang portion 313 are opposed to the internal electrode 210 via the piezoelectric layer 205, and form a displacement region due to the piezoelectric effect. For this reason, it is preferable that the first overhanging portion 312 and the second overhanging portion 313 are formed large as long as they are not short-circuited with the second external electrode 320. In addition, it is preferable that the displacement region of the first overhanging portion 312 and the second overhanging portion 313 coincide with each other in the thickness direction in relation to the internal electrode 210. This is to reduce the occurrence of stress at the interface between the displacement region and the non-displacement region or in the vicinity thereof and to prevent the occurrence of cracks. In the present embodiment, the first projecting portion 312 and the second projecting portion 313 have the same shape. The first external electrode 310 is formed of a metal such as Ag, Cu, Sn, Au, Ni, Fe, Pd, or Pt, or an alloy thereof. In this embodiment, an Ag—Pd alloy is used.

第２外部電極３２０は、圧電素子本体２００の他方の側面の全面に形成された側面部３２１と、振動板１０が付設されていない側の主面側に張り出した第１張出部３２２と、振動板１０が付設されている側の主面側に張り出した第２張出部３２３とを一体に形成してなる。側面部３２１は、内部電極２１０と電気的に接続している。第１張出部３２２及び第２張出部３２３は、圧電体層２０５を介して内部電極２１０と対向しているものの、該内部電極２１０と各張出部３２２，３２３とは電気的に接続しているので、両者間では圧電効果による変位領域は形成しない。このため、圧電効果という観点からは、第１張出部３２２及び第２張出部３２３の大きさは不問である。しかし、圧電素子本体２０１からの剥離を防止する等の観点から、第１外部電極３１０の大きさに影響を与えず、且つ、第１外部電極３１０と短絡しない範囲で大きく形成することが好ましい。第２外部電極３２０は、Ａｇ、Ｃｕ、Ｓｎ、Ａｕ、Ｎｉ，Ｆｅ、Ｐｄ、Ｐｔ等の金属やこれらの合金により形成される。本実施の形態ではＡｇ−Ｐｄ合金を用いた。 The second external electrode 320 includes a side surface portion 321 formed on the entire other side surface of the piezoelectric element body 200, a first extension portion 322 protruding to the main surface side on which the diaphragm 10 is not provided, A second projecting portion 323 projecting to the main surface side on which the diaphragm 10 is attached is integrally formed. The side surface portion 321 is electrically connected to the internal electrode 210. Although the first overhanging part 322 and the second overhanging part 323 face the internal electrode 210 through the piezoelectric layer 205, the internal electrode 210 and the overhanging parts 322 and 323 are electrically connected. Therefore, a displacement region due to the piezoelectric effect is not formed between the two. For this reason, the magnitude | size of the 1st overhang | projection part 322 and the 2nd overhang | projection part 323 is not ask | required from a viewpoint of a piezoelectric effect. However, from the standpoint of preventing peeling from the piezoelectric element body 201, it is preferable that the first external electrode 310 is formed large in a range that does not affect the size and does not short-circuit the first external electrode 310. The second external electrode 320 is made of a metal such as Ag, Cu, Sn, Au, Ni, Fe, Pd, or Pt, or an alloy thereof. In this embodiment, an Ag—Pd alloy is used.

圧電素子本体２００の一方の主面であって振動板１０が付設されていない側の主面には、第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２とが対向する領域に、第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２の何れか一方又は双方の一部を被覆する第１絶縁膜５０１が形成されている。本実施の形態では、第１絶縁膜５０１は第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２の双方の一部と、第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２の間隙を被覆している。 The first overhanging portion 312 of the first external electrode 310 and the first overhanging of the second external electrode 320 are formed on one main surface of the piezoelectric element body 200 where the diaphragm 10 is not attached. A first insulating film that covers a part of one or both of the first overhanging portion 312 of the first external electrode 310 and the first overhanging portion 322 of the second external electrode 320 in a region facing the portion 322; 501 is formed. In the present embodiment, the first insulating film 501 includes a part of both the first overhang portion 312 of the first external electrode 310 and the first overhang portion 322 of the second external electrode 320, and the first external electrode 310. The gap between the first overhang portion 312 and the first overhang portion 322 of the second external electrode 320 is covered.

圧電素子本体２００の他方の主面であって振動板１０が付設されている側の主面には、第１外部電極３１０の第２張出部３１３と第２外部電極３２０の第２張出部３２３の何れか一方又は双方の全面を被覆する第２絶縁膜５０２が形成されている。ここで、第２絶縁膜５０２は、第１外部電極３１０又は第２外部電極３２０の全面ではなく、振動板１０と対向している部位である第２張出部３１３又は３２３の何れか一方又は双方の全面に形成されるものであり、側面部３１１，３２１には形成されない点に留意されたい。本実施の形態では、第２外部電極３２０の第２張出部３２３の全面に第２絶縁膜５０２が形成されている。 The second overhanging portion 313 of the first external electrode 310 and the second overhanging of the second external electrode 320 are formed on the other main surface of the piezoelectric element body 200 on the side where the diaphragm 10 is attached. A second insulating film 502 that covers the entire surface of one or both of the portions 323 is formed. Here, the second insulating film 502 is not the entire surface of the first external electrode 310 or the second external electrode 320, but one of the second overhang portions 313 and 323 which are portions facing the diaphragm 10 or It should be noted that it is formed on the entire surface of both sides and is not formed on the side surface portions 311 and 321. In the present embodiment, the second insulating film 502 is formed on the entire surface of the second overhanging portion 323 of the second external electrode 320.

第１及び第２絶縁膜５０１，５０２としては、高硬度且つ均一性が良好なものが好ましい。これは、特に振動体１０との接着面に形成される第２絶縁膜５０２について顕著である。すなわち、第２絶縁膜５０２として樹脂のような柔らかい材質を用いると圧電体の変位をロスしてしまい、振動源としての効果を最大限発揮できなくなるためであるとともに、第２絶縁膜５０２が均一な膜でないと、素子に局部的な応力を発生させることとなり、素子を壊してしまうおそれがあるためである。 As the first and second insulating films 501 and 502, those having high hardness and good uniformity are preferable. This is particularly noticeable for the second insulating film 502 formed on the adhesive surface with the vibrating body 10. That is, if a soft material such as resin is used as the second insulating film 502, the displacement of the piezoelectric body is lost, and the effect as a vibration source cannot be exhibited to the maximum, and the second insulating film 502 is uniform. If the film is not a proper film, local stress is generated in the element, which may break the element.

そこで第１及び第２絶縁膜５０１，５０２としては、Ａｌ_２Ｏ_３やＳｉＯ_２、ＳｎＯ_２基膜であるＳｎＯ_２−ＩｎＯ_２−ＺｎＯ−ＳｉＯ_２など、各種絶縁性の酸化膜を用いる。本実施の形態では、（４４．２）ＳｎＯ_２−ＩｎＯ_２−ＺｎＯ−ＳｉＯ_２膜を用いた。当該材料を選択するに至った理由について説明する。 Therefore as the first and second insulating films 501 and 502, such _{as Al} 2 _{O 3} and _SnO _₂ -InO 2 -ZnO-SiO 2 is _SiO 2, SnO ₂ group film, using various insulating oxide film. In this embodiment, a (44.2) SnO ₂ —InO ₂ —ZnO—SiO ₂ film is used. The reason why the material has been selected will be described.

この（４４．２）ＳｎＯ_２−ＩｎＯ_２−ＺｎＯ−ＳｉＯ_２膜は、元来光ディスクの保護膜としての用途が一般的であり、絶縁性としての用途は一般的ではない。他方、ＳｉＯ_２は絶縁膜としての用途が知られているが、材質が不導体である。本実施の形態では、後述するように第１及び第２絶縁膜５０１，５０２をＤＣスパッタリングにより形成することを想定している。しかし、ＳｉＯ_２はＤＣスパッタができず、プラズマＣＶＤやＲＦスパッタを用いた膜生成となるために生成速度が非常に遅く、量産向きではない。また、ＩＴＯのように導電性を持たせることで、ＤＣスパッタとすることで膜の生成速度を向上できるが、これでは絶縁の用途から外れる。ターゲット材は導電性とし、反応性スパッタとして酸素量を増加させることで、ＤＣスパッタの膜生成速度と絶縁性を両立できるのが、この材料である。ここで、ターゲット材は導電性であるのに、できた膜が絶縁性であることがポイントとなる。これは、スパッタ時の酸素の量を最適とすることで、具現できている。また、ＩｎをＺｎで置き換えることで、ＩＴＯよりも安価にできている。スパッタ法で生成させるメリットとして、膜の密着性、均一性、ピンホールレスといった特徴があり、これらも圧電素子にとっては高効果となる。 This (44.2) SnO ₂ —InO ₂ —ZnO—SiO ₂ film is generally used as a protective film for optical discs, and is not generally used as an insulating material. On the other hand, SiO ₂ is known to be used as an insulating film, but is made of a non-conductive material. In the present embodiment, it is assumed that the first and second insulating films 501 and 502 are formed by DC sputtering as will be described later. However, SiO ₂ cannot be DC-sputtered, and the film is formed using plasma CVD or RF sputtering. Therefore, the production speed is very slow and not suitable for mass production. Further, by providing conductivity like ITO, the film formation rate can be improved by using DC sputtering, but this is not suitable for insulation. The target material is conductive, and by increasing the amount of oxygen as reactive sputtering, it is this material that can achieve both the film formation rate of DC sputtering and insulation. Here, although the target material is conductive, the point is that the formed film is insulative. This can be realized by optimizing the amount of oxygen during sputtering. Moreover, it is made cheaper than ITO by replacing In with Zn. Advantages generated by the sputtering method include characteristics such as film adhesion, uniformity, and pinholelessness, which are also highly effective for piezoelectric elements.

振動板１０は、４２アロイ，ステンレス鋼等の導電性材料、又は、液晶ポリマー，ＰＥＴ等の絶縁性材料で構成される。本実施の形態では、導電性材料である４２アロイを用いた。接着材２０は、圧電素子１００の主面の少なくとも一部に塗布される。接着材２０としては、各種一般的な物を用いることができるが、本実施の形態では、嫌気性ＵＶ硬化型接着剤を用いた。接着材２０は１０〜３０（μｍ）程度の厚さで塗布された後に加圧され、第１外部電極３１０が振動板１０と電気的に接続される。一方、第２外部電極３２０は第２絶縁膜５０２により振動板１０とは絶縁されている。 The diaphragm 10 is made of a conductive material such as 42 alloy or stainless steel, or an insulating material such as liquid crystal polymer or PET. In this embodiment, 42 alloy which is a conductive material is used. The adhesive 20 is applied to at least a part of the main surface of the piezoelectric element 100. Various common materials can be used as the adhesive 20, but an anaerobic UV curable adhesive is used in the present embodiment. The adhesive 20 is applied with a thickness of about 10 to 30 (μm) and then pressurized, and the first external electrode 310 is electrically connected to the diaphragm 10. On the other hand, the second external electrode 320 is insulated from the diaphragm 10 by the second insulating film 502.

次に、本実施の形態に係る圧電素子１００の製造方法について説明する。まず、圧電体層２０５に対応するセラミック圧電材料と、圧電素子本体２００の内層である内部電極２１０に対応する所定パターンの電極材料とを積層して積層体を得る。次に、この積層体を焼成する。次に、焼成した積層体を部品単位に裁断する。これにより内部電極２１０が側面に露出する。次に、スパッタリングなどの薄膜法により、第１外部電極３１０及び第２外部電極３２０を形成する。次に、ＤＣスパッタリングにより、第１及び第２絶縁膜５０１，５０２を形成する。最後に、分極処理を行うことで圧電素子１００が得られる。 Next, a method for manufacturing the piezoelectric element 100 according to the present embodiment will be described. First, a ceramic piezoelectric material corresponding to the piezoelectric layer 205 and an electrode material having a predetermined pattern corresponding to the internal electrode 210 which is the inner layer of the piezoelectric element body 200 are laminated to obtain a laminated body. Next, this laminate is fired. Next, the fired laminate is cut into parts. Thereby, the internal electrode 210 is exposed to the side surface. Next, the first external electrode 310 and the second external electrode 320 are formed by a thin film method such as sputtering. Next, first and second insulating films 501 and 502 are formed by DC sputtering. Finally, the piezoelectric element 100 is obtained by performing polarization treatment.

このように本実施の形態に係る圧電素子１００によれば、圧電素子本体２００の一方の主面に形成された第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２をリード線の半田付け箇所として用いることができる。これにより実装密度及び実装自由度が向上する。ここで第１外部電極３１０の第１張出部３１２の露出領域と第２外部電極３２０の第１張出部３２２の露出領域との間隔は第１絶縁膜５０１により十分に確保されている。これにより両電極の短絡を防止することができ、リード線等の実装容易性も向上する。なお、第１外部電極３１０は振動板１０と導通している。このため、リード線等を第１外部電極３１０ではなく振動板１０に接続するようにしてもよい。 As described above, according to the piezoelectric element 100 according to the present embodiment, the first overhanging portion 312 of the first external electrode 310 and the first of the second external electrode 320 formed on one main surface of the piezoelectric element body 200. The overhanging portion 322 can be used as a soldering portion of the lead wire. This improves the mounting density and the degree of freedom of mounting. Here, a distance between the exposed region of the first overhanging portion 312 of the first external electrode 310 and the exposed region of the first overhanging portion 322 of the second external electrode 320 is sufficiently secured by the first insulating film 501. Thereby, a short circuit of both electrodes can be prevented, and the ease of mounting of lead wires and the like is improved. The first external electrode 310 is electrically connected to the diaphragm 10. For this reason, a lead wire or the like may be connected to the diaphragm 10 instead of the first external electrode 310.

また本実施の形態に係る圧電素子１００では、圧電素子本体２００の他方の主面に形成された第１外部電極３１０の第２張出部３１３と第２外部電極３２０の第２張出部３２３の何れか一方又は双方の全面に第２絶縁膜５０２が形成されるので、電極間が振動板１０により短絡することを防止できる。すなわち、圧電素子１００の取付先である振動板１０や接着材２０が導電性を有しているか否かを気にする必要がないので、使い勝手が向上する。 In the piezoelectric element 100 according to the present embodiment, the second overhang 313 of the first external electrode 310 and the second overhang 323 of the second external electrode 320 formed on the other main surface of the piezoelectric element body 200. Since the second insulating film 502 is formed on the entire surface of one or both of the electrodes, it is possible to prevent the electrodes from being short-circuited by the diaphragm 10. That is, since it is not necessary to worry about whether the diaphragm 10 or the adhesive 20 to which the piezoelectric element 100 is attached has conductivity, the usability is improved.

また、圧電素子本体２００の一方の主面に形成された第１外部電極３１０の第１張出部３１２は、第２外部電極３２０の第１張出部３２２との間隔を確保するために形成面積を小さくしているわけではないので、変位領域を十分に確保することができる。さらに、第１外部電極３１０の第１張出部３１２と内部電極３２０による変位領域と、他方の主面に形成された第１外部電極３１０の第２張出部３１３と内部電極３２０による変位領域とは厚み方向で一致している。これにより、変位領域と非変位領域との界面又はその近傍での応力の発生を軽減できるので、クラックの発生などを防止できる。 In addition, the first overhanging portion 312 of the first external electrode 310 formed on one main surface of the piezoelectric element body 200 is formed in order to ensure a distance from the first overhanging portion 322 of the second external electrode 320. Since the area is not reduced, a sufficient displacement region can be secured. Further, the displacement region by the first overhanging portion 312 and the internal electrode 320 of the first external electrode 310, and the displacement region by the second overhanging portion 313 of the first external electrode 310 and the internal electrode 320 formed on the other main surface. And match in the thickness direction. Thereby, since the generation of stress at the interface between the displacement region and the non-displacement region or in the vicinity thereof can be reduced, the generation of cracks and the like can be prevented.

なお、上記実施の形態では、第１絶縁膜５０１は第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２の双方の一部を被覆しているが、何れか一方の一部のみを被覆するように構成してもよい。 In the above embodiment, the first insulating film 501 covers a part of both the first overhanging portion 312 of the first external electrode 310 and the first overhanging portion 322 of the second external electrode 320. Alternatively, only a part of either one may be covered.

同様に、上記実施の形態では、第２絶縁膜５０２は第２外部電極３２０の第２張出部３２３の全面のみを被覆しているが、第１外部電極３１０の第２張出部３１３の全面のみを被覆してもよいし、第１外部電極３１０の第２張出部３１３及び第２外部電極３２０の第２張出部３２３の双方の全面を被覆してもよい。前者の場合、第２外部電極３２０と振動板１０が電気的に接続されるので、第２外部電極３２０ではなく振動板１０をリード線等の接続位置とすることができる。また、上記実施の形態では、第２絶縁膜５０２は第２外部電極３２０の第２張出部３２３の全面のみを被覆し、振動板１０を圧電素子本体１００に加圧接着することにより、第１外部電極１００と振動板１０とを導通状態にしているが、接着材２０の厚みや材料等を適宜選択することにより第１外部電極１００と振動板１０とを絶縁状態としてもよい。このような変形例は、前述したような、第１外部電極３１０の第２張出部３１３の全面を第２絶縁膜５０２で被覆した場合にも同様である。 Similarly, in the above embodiment, the second insulating film 502 covers only the entire surface of the second overhanging portion 323 of the second external electrode 320, but the second overhanging portion 313 of the first external electrode 310 is covered. Only the entire surface may be covered, or the entire surface of both the second overhanging portion 313 of the first external electrode 310 and the second overhanging portion 323 of the second external electrode 320 may be covered. In the former case, since the second external electrode 320 and the diaphragm 10 are electrically connected, it is possible to use the diaphragm 10 instead of the second external electrode 320 as a connection position such as a lead wire. In the above embodiment, the second insulating film 502 covers only the entire surface of the second overhanging portion 323 of the second external electrode 320, and the diaphragm 10 is pressure-bonded to the piezoelectric element body 100, whereby the first 1 The external electrode 100 and the diaphragm 10 are in a conductive state, but the first external electrode 100 and the diaphragm 10 may be in an insulated state by appropriately selecting the thickness and material of the adhesive 20. Such a modification is the same when the entire surface of the second overhanging portion 313 of the first external electrode 310 is covered with the second insulating film 502 as described above.

また、上記実施の形態では、振動板１０の一方の主面に１つの圧電素子１００を付設したユニモルフ型の圧電素子について説明したが、図２に示すように、振動板１０の両面に上記の圧電素子１００を付設してバイモルフ型の圧電素子を構成するようにしてもよい。なおこの場合、上下の素子で分極の特性が異なる点に留意されたい。 In the above embodiment, a unimorph type piezoelectric element in which one piezoelectric element 100 is attached to one main surface of the diaphragm 10 has been described. However, as shown in FIG. A bimorph piezoelectric element may be configured by attaching the piezoelectric element 100. In this case, it should be noted that polarization characteristics differ between the upper and lower elements.

（第２の実施の形態）
本発明の一実施の形態に係る圧電素子について図面を参照して説明する。図３は圧電素子の断面図である。なお同図は、本発明の特徴を明瞭にすべく模式的に記載したものであり、必ずしも実物とは寸法比等が一致しない点に留意されたい。 (Second Embodiment)
A piezoelectric element according to an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a sectional view of the piezoelectric element. It should be noted that this figure is schematically described in order to clarify the features of the present invention, and the dimensional ratio and the like do not necessarily match those of the actual product.

本実施の形態に係る圧電素子が第１の実施の形態と異なる点は、圧電素子本体２００の層構造及び外部電極の構造にある。具体的には、第１の実施の形態では圧電体層２０５が偶数（２つ）の層構造であったが、本実施の形態では圧電体層２０５が奇数（３つ）の層構造になっている点が異なり、これに伴い外部電極の構造も異なる。その他の点については第１の実施の形態と同様なので、ここでは相違点のみを説明する。 The piezoelectric element according to the present embodiment is different from the first embodiment in the layer structure of the piezoelectric element body 200 and the structure of the external electrode. Specifically, in the first embodiment, the piezoelectric layer 205 has an even (two) layer structure, but in the present embodiment, the piezoelectric layer 205 has an odd (three) layer structure. The structure of the external electrode is also different. Since the other points are the same as those of the first embodiment, only the differences will be described here.

本実施の形態に係る圧電素子１０１の圧電素子本体２０１は、図３に示すように、複数（本実施の形態では３つ）の圧電体層２０５と、２つの内部電極２１１，２１２とを積層してなる。 As shown in FIG. 3, the piezoelectric element body 201 of the piezoelectric element 101 according to the present embodiment is formed by laminating a plurality of (three in the present embodiment) piezoelectric layers 205 and two internal electrodes 211 and 212. Do it.

内部電極２１１，２１２は、交互に圧電素子本体２００の異なる側面に露出する。具体的には、一方の内部電極２１１は、圧電素子本体２００の一方の側面に露出し、第２外部電極３２０に電気的に接続する。他方の内部電極２１２は、圧電素子本体２００の他方の側面に露出し、第１外部電極３１０に電気的に接続する。一方の内部電極２１１は、圧電体層２０５を介して対向する他の内部電極２１２、及び、第１外部電極３１０であって圧電素子本体２００の主面に形成された部位と対向し、圧電効果による変位領域を形成する。他方の内部電極２１２は、圧電体層２０５を介して対向する他の内部電極２１１、及び、第２外部電極３２０であって圧電素子本体２００の他方の主面に形成された部位と対向し、圧電効果による変位領域を形成する。 The internal electrodes 211 and 212 are alternately exposed on different side surfaces of the piezoelectric element body 200. Specifically, one internal electrode 211 is exposed on one side surface of the piezoelectric element body 200 and is electrically connected to the second external electrode 320. The other internal electrode 212 is exposed on the other side surface of the piezoelectric element body 200 and is electrically connected to the first external electrode 310. One internal electrode 211 opposes the other internal electrode 212 and the first external electrode 310 that are opposed to each other through the piezoelectric layer 205 and is formed on the main surface of the piezoelectric element body 200, and the piezoelectric effect. A displacement region is formed by. The other internal electrode 212 opposes the other internal electrode 211 that opposes the piezoelectric layer 205, and the second external electrode 320 that is a part formed on the other main surface of the piezoelectric element body 200, A displacement region due to the piezoelectric effect is formed.

第１外部電極３１０は、圧電素子本体２００の一方の側面の全面に形成された側面部３１１と、振動板１０が付設されていない側の主面側に張り出した第１張出部３１２と、振動板１０が付設されている側の主面側に張り出した第２張出部３１３とを一体に形成してなる。側面部３１１は内部電極２１２と接続している。第１張出部３１２は、圧電体層２０５を介して内部電極２１１と対向し、圧電効果による変位領域を形成する。このため、第１張出部３１２は、第２外部電極３２０と短絡しない範囲で大きく形成することが好ましい。一方、第２張出部３１３は、圧電体層２０５を介して内部電極２１２と対向しているものの、該内部電極２１２と第２張出部３１３とは電気的に接続しているので、両者間では圧電効果による変位領域は形成しない。このため、圧電効果という観点からは、第２張出部３１３の大きさは不問である。しかし、圧電素子本体２０１からの剥離を防止する等の観点から、第２外部電極３２０の大きさに影響を与えず、且つ、第２外部電極３２０と短絡しない範囲で大きく形成することが好ましい。 The first external electrode 310 includes a side surface portion 311 formed on the entire surface of one side surface of the piezoelectric element body 200, a first overhang portion 312 overhanging on the main surface side where the diaphragm 10 is not provided, A second projecting portion 313 projecting to the main surface side where the diaphragm 10 is attached is integrally formed. The side surface portion 311 is connected to the internal electrode 212. The first overhang portion 312 faces the internal electrode 211 via the piezoelectric layer 205 and forms a displacement region due to the piezoelectric effect. For this reason, it is preferable that the first overhang portion 312 is formed to be large as long as the second external electrode 320 is not short-circuited. On the other hand, although the second overhanging portion 313 is opposed to the internal electrode 212 through the piezoelectric layer 205, the internal electrode 212 and the second overhanging portion 313 are electrically connected. A displacement region due to the piezoelectric effect is not formed between them. For this reason, the magnitude | size of the 2nd overhang | projection part 313 is not ask | required from a viewpoint of a piezoelectric effect. However, from the viewpoint of preventing peeling from the piezoelectric element body 201, it is preferable that the second external electrode 320 is not greatly affected and is formed large in a range not short-circuited with the second external electrode 320.

第２外部電極３２０は、圧電素子本体２００の他方の側面の全面に形成された側面部３２１と、振動板１０が付設されていない側の主面側に張り出した第１張出部３２２と、振動板１０が付設されている側の主面側に張り出した第２張出部３２３とを一体に形成してなる。側面部３２１は内部電極２１１と接続している。第２張出部３２３は、圧電体層２０５を介して内部電極２１２と対向し、圧電効果による変位領域を形成する。このため、第２張出部３２３は、第１外部電極３１０と短絡しない範囲で大きく形成することが好ましい。一方、第１張出部３２２は、内部電極２１１と圧電体層２０５を介して対向しているものの、該内部電極２１１と第１張出部３２２とは電気的に接続しているので、両者間では圧電効果による変位領域は形成しない。このため、圧電効果という観点からは、第１張出部３２２の大きさは不問である。しかし、圧電素子本体２０１からの剥離を防止する等の観点から、第１外部電極３１０の大きさに影響を与えず、且つ、第１外部電極３１０と短絡しない範囲で大きく形成することが好ましい。 The second external electrode 320 includes a side surface portion 321 formed on the entire other side surface of the piezoelectric element body 200, a first extension portion 322 protruding to the main surface side on which the diaphragm 10 is not provided, A second projecting portion 323 projecting to the main surface side on which the diaphragm 10 is attached is integrally formed. The side surface portion 321 is connected to the internal electrode 211. The second overhang portion 323 faces the internal electrode 212 through the piezoelectric layer 205 and forms a displacement region due to the piezoelectric effect. For this reason, it is preferable to form the 2nd overhang | projection part 323 large in the range which does not short-circuit with the 1st external electrode 310. FIG. On the other hand, although the first overhanging portion 322 is opposed to the internal electrode 211 via the piezoelectric layer 205, the internal electrode 211 and the first overhanging portion 322 are electrically connected. A displacement region due to the piezoelectric effect is not formed between them. For this reason, the magnitude | size of the 1st overhang | projection part 322 is not ask | required from a viewpoint of a piezoelectric effect. However, from the standpoint of preventing peeling from the piezoelectric element body 201, it is preferable that the first external electrode 310 is formed large in a range that does not affect the size and does not short-circuit the first external electrode 310.

本実施の形態に係る圧電素子１００では、第１外部電極３１０の第１張出部３１２と内部電極２１１との間、内部電極２１１と内部電極２１２との間、内部電極２１２と第２外部電極３２０の第２張出部３２３との間は、圧電効果による変位領域となる。ここで各変位領域は、厚み方向に一致するように各部の寸法が規定されている。 In the piezoelectric element 100 according to the present embodiment, between the first projecting portion 312 and the internal electrode 211 of the first external electrode 310, between the internal electrode 211 and the internal electrode 212, and between the internal electrode 212 and the second external electrode. Between the second overhanging portions 323 of 320 is a displacement region due to the piezoelectric effect. Here, the dimension of each part is prescribed | regulated so that each displacement area may correspond to the thickness direction.

圧電素子本体２０１の一方の主面であって振動板１０が付設されていない側の主面には、第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２とが対向する領域に、第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２の何れか一方又は双方の一部を被覆する第１絶縁膜５０１が形成されている。本実施の形態では、第１絶縁膜５０１は第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２の双方の一部と、第１外部電極３１０の第１張出部３１２と第２外部電極３２０の第１張出部３２２の間隙を被覆している。 The first overhanging portion 312 of the first external electrode 310 and the first overhanging of the second external electrode 320 are formed on one main surface of the piezoelectric element body 201 that is not provided with the diaphragm 10. A first insulating film that covers a part of one or both of the first overhanging portion 312 of the first external electrode 310 and the first overhanging portion 322 of the second external electrode 320 in a region facing the portion 322; 501 is formed. In the present embodiment, the first insulating film 501 includes a part of both the first overhang portion 312 of the first external electrode 310 and the first overhang portion 322 of the second external electrode 320, and the first external electrode 310. The gap between the first overhang portion 312 and the first overhang portion 322 of the second external electrode 320 is covered.

圧電素子本体２０１の他方の主面であって振動板１０が付設されている側の主面には、第１外部電極３１０の第２張出部３１３と第２外部電極３２０の第２張出部３２３の何れか一方又は双方の全面を被覆する第２絶縁膜５０２が形成されている。本実施の形態では、第２外部電極３２０の第２張出部３２３の全面に第２絶縁膜５０２が形成されている。 On the other main surface of the piezoelectric element body 201 on the side where the diaphragm 10 is attached, the second overhanging portion 313 of the first external electrode 310 and the second overhanging of the second external electrode 320 are provided. A second insulating film 502 that covers the entire surface of one or both of the portions 323 is formed. In the present embodiment, the second insulating film 502 is formed on the entire surface of the second overhanging portion 323 of the second external electrode 320.

本実施の形態に係る圧電素子１０１によれば、第１の実施の形態と同様の作用・効果を得ることができる。なお、本実施の形態に対しても第１の実施の形態と同様の変形例を適用できる。例えば、本実施の形態では、振動板１０の一方の主面に１つの圧電素子１０１を付設したユニモルフ型の圧電素子について説明したが、図４に示すように、振動板１０の両面に上記の圧電素子１０１を付設してバイモルフ型の圧電素子を構成するようにしてもよい。なおこの場合、上下の素子で分極の特性が異なる点に留意されたい。 According to the piezoelectric element 101 according to the present embodiment, it is possible to obtain the same operations and effects as those of the first embodiment. Note that the same modification as in the first embodiment can be applied to the present embodiment. For example, in the present embodiment, a unimorph type piezoelectric element in which one piezoelectric element 101 is provided on one main surface of the diaphragm 10 has been described. However, as shown in FIG. A piezoelectric element 101 may be attached to form a bimorph type piezoelectric element. In this case, it should be noted that polarization characteristics differ between the upper and lower elements.

以上本発明の実施の形態について詳述したが、本発明はこれに限定されるものではない。例えば上記第１の実施の形態では圧電体層２０５が２つ、第２の実施の形態では圧電体層２０５が３つのものを例示したが、さらに圧電体層２０５の層数を増やしても本発明を適用できる。 Although the embodiment of the present invention has been described in detail above, the present invention is not limited to this. For example, in the first embodiment, two piezoelectric layers 205 are exemplified, and in the second embodiment, three piezoelectric layers 205 are exemplified. However, even if the number of piezoelectric layers 205 is further increased, the number of piezoelectric layers 205 is increased. The invention can be applied.

１００，１０１…圧電素子、２００，２０１…圧電素子本体、２０５…圧電体層、２１０，２１１，２１２…内部電極、３１０…第１外部電極、３１１…側面部、３１２…第１張出部、３１３…第２張出部、３２０…第２外部電極、３２１…側面部、３２２…第１張出部、３２３…第２張出部、５０１…第１絶縁膜、５０２…第２絶縁膜、１０…振動板、２０…接着剤 DESCRIPTION OF SYMBOLS 100,101 ... Piezoelectric element, 200, 201 ... Piezoelectric element body, 205 ... Piezoelectric layer, 210, 211, 212 ... Internal electrode, 310 ... First external electrode, 311 ... Side face part, 312 ... First overhang part, 313: 2nd overhanging part, 320 ... 2nd external electrode, 321 ... side surface part, 322 ... 1st overhanging part, 323 ... 2nd overhanging part, 501 ... 1st insulating film, 502 ... 2nd insulating film, 10 ... diaphragm, 20 ... adhesive

Claims

A piezoelectric element body formed by laminating a piezoelectric layer and one or a plurality of internal electrodes, a first external electrode formed from one side surface of the piezoelectric element body to the main surface, and the other side surface of the piezoelectric element body A piezoelectric element electrically connected to one of the first external electrode and the second external electrode on the side surface of the piezoelectric element body.
An insulating film is formed on the main surface of the piezoelectric element body so as to cover at least a part of one or both of the first external electrode and the second external electrode in a region opposite to the first external electrode and the second external electrode. A characteristic piezoelectric element.

A diaphragm attached to one main surface of the piezoelectric element body,
The piezoelectric element according to claim 1, wherein the insulating film is formed on the other main surface of the piezoelectric element body.

A diaphragm attached to one main surface of the piezoelectric element body,
2. The piezoelectric element according to claim 1, wherein the insulating film is formed so as to cover the entire surface of one or both of the first external electrode and the second external electrode on the one main surface of the piezoelectric element body. .

A diaphragm attached to one main surface of the piezoelectric element body,
The insulating film is formed on both main surfaces of the piezoelectric element body, and one main surface of the piezoelectric element body is formed so as to cover the entire surface of one or both of the first external electrode and the second external electrode. The piezoelectric element according to claim 1, wherein: