JPH0730163A - Laminated piezoelectric substance element - Google Patents

Abstract

PURPOSE:To provide a laminated piezoelectric substance element wherein the flatness of the surface and the rear surface on which electrodes are formed is excellent, when a laminated plezoelectric actuator is constituted by stacking and bonding a plurality of elements, the stability of their bonding is excellent, no destruction is caused by an external force and the laminated plezoelectric actuator of high reliability can be obtained. CONSTITUTION:At least one out of external electrodes 4a, 4b on the surface and the rear surface of a laminated body 3 by piezoelectric substance layers 1 and internal electrodes 2a, 2b is formed as a thin-film electrode. The thin-film electrodes 4a, 4b are extended up to side faces 3c, 34 on the laminated body 3, and they are set to direct continuity with external electrodes 4c, 4d formed on the side faces 3c, 34 on the laminated body 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated piezoelectric element, and more specifically, a laminated body in which an external electrode electrically connected to the internal electrode is provided outside a laminated body of a piezoelectric layer and an internal electrode. Type piezoelectric element.

[0002]

2. Description of the Related Art As a laminated piezoelectric actuator using a piezoelectric material, for example, as shown in FIG. 5, an internal electrode 52 having a partial electrode structure is provided between a plurality of piezoelectric material layers 51, and a piezoelectric material is provided. A laminate formed by arranging an external electrode 54 made of a thick film electrode so as to wrap around a laminated body 53 composed of a body layer 51 and an internal electrode 52 from the side surface from which the internal electrode 52 is drawn out to the upper and lower surfaces thereof. There is proposed a laminated piezoelectric actuator having a structure in which a plurality of type piezoelectric elements 55 are stacked via a metal plate 56, and a predetermined metal plate 56 is connected by a lead wire 57 and fixed by spring pressure or the like.

In the laminated piezoelectric element 55 constituting the above laminated piezoelectric actuator, the internal electrode 5 is used.
As shown in FIG. 6, 2 is alternately drawn to the opposite end so as to be electrically connected to the external electrode 54 (FIG. 5) on the opposite side every other layer.

In this laminated piezoelectric actuator, the metal plate 56 inserted between each laminated piezoelectric element 55 and the external formed so as to wrap around the upper and lower surfaces of each laminated piezoelectric element 55. There is an advantage that electrical connection between the internal electrode 52 and the metal plate 56 can be obtained only by making contact with the electrode 54.

[0005]

However, in the above-mentioned laminated piezoelectric actuator, the laminated piezoelectric element 55 is used.
External electrodes 54 are formed so as to wrap around from the side surface of the laminate 53 to the upper and lower surfaces (for example, by printing the thick film electrodes on the upper and lower surfaces and directly connecting to the thick film electrodes formed on the side surfaces). The external electrode 54 is formed by such a method as described above). Therefore, as shown in FIG. 7, a bump (bump) 5 is formed on the external electrode 54 made of a thick film electrode at a corner portion of the laminated body 53.
8 occurs, and the flatness of the upper and lower surfaces of the laminated piezoelectric element 55 is impaired. Therefore, when a plurality of laminated piezoelectric elements 55 are stacked with the metal plate 56 in between, the stacked state (connected and fixed state) becomes unstable, and the stacked piezoelectric elements 55 cannot be securely fixed, or as a laminated piezoelectric actuator. When used, there is a problem that destruction may occur due to external force.

The present invention solves the above-mentioned problems and is excellent in flatness of the upper and lower surfaces on which electrodes are formed,
When a multilayer piezoelectric actuator is constructed by stacking and bonding a plurality of layers, it is possible to obtain a highly reliable multilayer piezoelectric actuator that has excellent bonding stability and is not broken by external force. It is an object to provide a laminated piezoelectric element.

[0007]

In order to achieve the above object, a laminated piezoelectric element according to the present invention has a plurality of piezoelectric layers, internal electrodes arranged between the piezoelectric layers, and internal electrodes extended. A thin-film piezoelectric element having at least one of the external electrodes on the upper and lower surfaces of the laminate of the piezoelectric layer and the internal electrode, and a thin film electrode. In addition, the thin film electrode is made to wrap around to the side surface of the laminated body so that the thin film electrode is directly connected to the external electrode formed on the side surface of the laminated body.

The present invention is not limited to the case where both the upper and lower external electrodes are thin film electrodes, but includes the case where only one of the upper and lower external electrodes is a thin film electrode.

In the laminated piezoelectric element of the present invention, various thin film forming methods such as a sputtering method and a vapor deposition method can be applied as a method of forming the thin film electrodes on the upper and lower surfaces.

[0010]

In the laminated piezoelectric element of the present invention,
As a thin film electrode with a small thickness and excellent flatness is used as the external electrode on the bottom surface, the rise at the corners between the top / bottom surface and the side surface of the laminated body is increased by using the conventional thick film electrode. It is significantly smaller than that of the external electrodes, and it is possible to improve the flatness of the upper and lower surfaces after the external electrodes are formed. By wrapping around the upper and lower surfaces, it is possible to secure the flatness of the upper and lower surfaces even when the outer electrodes on the upper and lower surfaces are directly connected to the external electrodes formed on the side surfaces of the laminate.

[0011]

EXAMPLES The features of the present invention will be described below in more detail with reference to examples. FIG. 1 is a sectional view showing a laminated piezoelectric element according to an embodiment of the present invention. In the multi-layer piezoelectric element 5 of this embodiment, a plurality of piezoelectric layers (for example, piezoelectric layers made of lead zirconate titanate-based material) 1 and a plurality of piezoelectric layers 1 are provided, and every other layer. The laminated body 3 is formed of the internal electrodes 2a and 2b drawn out to the two side surfaces facing each other.

The two side surfaces 3c and 3d facing each other of the laminated body 3 are made of thick film electrodes which are electrically connected to the internal electrodes 2a and 2b of the same pole drawn out to the side surfaces 3c and 3d. Electrodes 4c and 4d are formed. further,
External electrodes 4a and 4b made of thin film electrodes are formed on the upper and lower surfaces 3a and 3b of the laminated body 3. Also on this
The external electrodes (thin film electrodes) 4a and 4b on the lower surface side are the laminated body 3
It is formed so as to wrap around to the side faces 3c, 3d via the corners of the, and is in direct conduction with the external electrodes 4c, 4d formed on the side faces 3c, 3d of the laminated body 3.

Next, a method of manufacturing the laminated piezoelectric element 5 of the above embodiment will be described. In manufacturing the laminated piezoelectric element 5, first, in order to manufacture a piezoelectric layer (green sheet), raw materials are weighed, pulverized, mixed with a binder, defoamed, and then molded into a sheet shape. Then, punch it into a predetermined shape. Then, the internal electrodes are printed on it.

Next, the piezoelectric layers (green sheets) are laminated and pressure-bonded, cut into a predetermined shape, and fired to obtain a laminated body. Then, after forming external electrodes (thick film electrodes) on the side surfaces of the obtained laminated body from which the internal electrodes are drawn out, the upper and lower surfaces of the laminated body are lapped to be flat.

Then, as shown in FIG. 2 (a), after the metal mask 6 having a predetermined shape is applied to the two corners of the laminate 3 at diagonal positions, for example, a vapor deposition method, a sputtering method, or the like. 2B, as shown in FIG. 2B, from the upper and lower surfaces 3a and 3b of the laminated body 3 to the side surfaces 3c, through the corners.
External electrodes 4a and 4b made of thin film electrodes are formed so as to wrap around to 3d. At this time, since the metal mask 6 is applied, it is possible to prevent the thin film electrode from adhering to an unnecessary portion during vapor deposition or sputtering. In this way, the upper and lower external electrodes 4a, 4b
By wrapping around the side surfaces 3c and 3d of the laminated body 3, the external electrodes 4a and 4b on the upper and lower surfaces are directly connected to the external electrodes 4c and 4d formed on the side surfaces of the laminated body 3. Then, by removing the metal mask 6, the laminated piezoelectric element 5 as shown in FIG. 1 can be obtained.

In the laminated piezoelectric element 5 thus formed, the outer electrodes 4a and 4b on the upper and lower surfaces are formed of thin film electrodes, so that the corners of the laminated body 3 are almost free of protrusions. (For example, when the conventional thick film electrode is used, the rise height reaches up to around 100 μm, whereas when the thin film electrode is used, the rise height is suppressed to about several μm. Therefore, the flatness of the upper and lower surfaces after the external electrodes 4a and 4b are formed can be remarkably improved as compared with the case of the conventional laminated piezoelectric element using the thick film electrode. In addition, since the upper and lower external electrodes 4a and 4b wrap around to the side surfaces 3c and 3d via the corners of the laminated body 3, the upper and lower external electrodes 4a and 4b are formed.
b is the external electrode 4 formed on the side surfaces 3c and 3d of the laminate 3.
Even when directly connected to c and 4d, the flatness of the upper and lower surfaces is not impaired. In the laminated piezoelectric element 5 of the above embodiment, the upper and lower external electrodes 4a and 4b are provided.
The external electrodes on the side surfaces can be made conductive with a resistance of 10Ω or less.

Further, since the upper and lower surfaces of the laminated piezoelectric element 5 are flat, as shown in FIG. 3, a plurality of laminated piezoelectric elements 5 are stacked with the metal plate 7 interposed therebetween, and spring pressure or the like is applied. When the laminated piezoelectric actuator is formed by fixing with a mechanical force, the laminated piezoelectric elements 5 can be stably stacked, so that the laminated piezoelectric actuator has excellent bonding stability and high reliability. Can be obtained.

Further, as shown in FIG. 4, the internal electrodes 2a and 2b and the external electrodes 4c and 4 which are drawn out to different side surfaces from the upper and lower surfaces to the side surfaces of the laminated piezoelectric element 5.
Two external electrodes 14a, 15a and 1 which are electrically connected via d
4b and 15b are formed, the external electrodes 14a and 14b, and 15a and 15b facing each other on the joint surface are directly connected, and each laminated piezoelectric element 5 is adhered with an adhesive 8 to form a laminated piezoelectric actuator. With this structure, it is unnecessary to dispose a metal plate or to connect an external electrode formed on the side surface by soldering a lead wire, and a structure and a manufacturing method of the laminated piezoelectric actuator. Can be simplified.

The present invention is not limited to the above-mentioned embodiment, but the kind and composition of the material forming the piezoelectric layer, the specific shape and the number of laminated layers of the piezoelectric layer, the internal electrode and the external electrode. With regard to the constituent materials of (1), the method of forming an external electrode (thin film electrode), and the like, various applications and modifications can be made within the scope of the invention.

[0020]

As described above, in the laminated piezoelectric element of the present invention, at least one of the external electrodes on the upper and lower surfaces of the laminate of the piezoelectric layer and the internal electrode is a thin film electrode, and the thin film electrode is By wrapping around to the side surface of the laminated body, it is possible to directly conduct electricity to the external electrodes formed on the side surface of the laminated body, so that it is possible to suppress the occurrence of swelling on the external electrodes on the upper and lower surfaces, It is possible to obtain a laminated piezoelectric element having excellent flatness of the upper and lower surfaces.

When a plurality of laminated piezoelectric elements according to the present invention are stacked to form a laminated piezoelectric actuator, the stacking (coupling and fixing) is excellent in stability and there is no destruction by external force. It is possible to obtain a highly reliable laminated piezoelectric actuator.

[Brief description of drawings]

FIG. 1 is a sectional view showing a laminated piezoelectric element according to an embodiment of the present invention.

2A and 2B are diagrams showing a method for manufacturing a laminated piezoelectric element according to an embodiment of the present invention, FIG. 2A is a sectional view showing a state before forming upper and lower external electrodes, and FIG. FIG. 4 is a cross-sectional view showing a state after forming upper and lower external electrodes.

FIG. 3 is a cross-sectional view showing a main part of a laminated piezoelectric actuator configured by stacking laminated piezoelectric elements according to an embodiment of the present invention.

FIG. 4 is a sectional view showing a main part of another laminated piezoelectric actuator configured by stacking laminated piezoelectric elements according to an embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a conventional laminated piezoelectric actuator.

FIG. 6 is an exploded perspective view showing a pattern of internal electrodes of a laminated piezoelectric element that constitutes a conventional laminated piezoelectric actuator.

FIG. 7 is a cross-sectional view showing a main part of a laminated piezoelectric element that constitutes a conventional laminated piezoelectric actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric layer 2a, 2b Internal electrode 3 Laminated body 3a, 3b Upper and lower surfaces of laminated body 3c, 3d Side surface of laminated body 4a, 4b External electrode on upper and lower surfaces 4c, 4d External electrode on side surface 5 Laminated piezoelectric element 6 Metal mask 7 Metal plate 8 Adhesive

Claims (1)

[Claims] 1. A laminated piezoelectric body comprising a plurality of piezoelectric layers, internal electrodes arranged between the piezoelectric layers, side surfaces from which the internal electrodes are drawn out, and external electrodes formed on the upper and lower surfaces. In the body element, at least one of the external electrodes on the upper and lower surfaces of the laminated body of the piezoelectric layer and the internal electrode is used as a thin film electrode, and the thin film electrode is wrapped around to the side surface of the laminated body so that A laminated piezoelectric element characterized in that it is electrically connected to an external electrode formed on the substrate.