JPH0722664A - Manufacture of lamination type piezoelectric element - Google Patents

Abstract

PURPOSE:To readily and surely prevent an outside electrode from creeping in upper/lower surfaces of a lamination body without providing a dummy layer, etc., and to ensure flatness of upper/lower surfaces without enlarging an element thickness especially and providing a lapping process. CONSTITUTION:A substance 12 which repels a material for an outside electrode formation is applied to upper/lower surfaces 3a, 3b of a lamination body 3 of a piezoelectric layer 1 and inside electrodes 2a, 2b. In the state, materials 14a, 14b for outside electrode formation are attached to side surfaces 3c, 3d wherein inside electrodes 2a, 2b are extracted. An outside electrode is thereby formed.

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 particularly, to a side surface of a laminated body of a piezoelectric layer and an internal electrode, the external electrode being electrically connected to the internal electrode arranged between the piezoelectric layers. The present invention relates to a method for manufacturing a laminated piezoelectric element that is disposed in the.

[0002]

2. Description of the Related Art As a laminated piezoelectric actuator using a piezoelectric material, for example, as shown in FIGS. 5A and 5B, a plurality of piezoelectric material layers 51 are formed between a plurality of piezoelectric material layers 51. An internal electrode 52 having a partial electrode structure is provided, and a side surface of the laminated body 53 including the piezoelectric layer 51 and the internal electrode 52 from which the internal electrode 52 is drawn out is electrically connected to the internal electrode of the same pole (that is, There has been proposed a laminated piezoelectric actuator having a structure in which a laminated piezoelectric element 55 having an external electrode 54 in which internal electrodes of the same pole are connected in parallel is disposed in a case (not shown).

In the above-described laminated piezoelectric element 55, the internal electrodes 52 are alternately arranged so as to be electrically connected to the external electrodes 54 (FIG. 5) on the opposite side surface every other layer, as shown in FIG. It is pulled out to the opposite end.

As the external electrode 54, the internal electrode 5 is used.
The thick film electrode is used in consideration of the certainty of conduction with 2.

By the way, the above conventional laminated piezoelectric element 5 is used.
In FIG. 5, since the thickness of the piezoelectric layer 51 is usually as thin as 200 μm or less, as shown in FIGS. 5A and 5B, when the external electrode 54 is attached to the side surface of the laminated body 53, the laminated body 53 is formed. The upper and lower end portions 54a and 54b of the outer electrode 54 can be reliably connected to the upper and lowermost inner electrodes 52 and outer electrodes 54 that are drawn to the side surfaces of the outer electrode 54.
However, the external electrode 54 is formed so as to wrap around from the corner portion (edge portion) of the laminated body 53 to the upper and lower surfaces thereof.

Therefore, the portions 54a and 54b of the external electrode 54 that extend around the upper and lower surfaces of the laminated body 53 become obstacles when the laminated piezoelectric element 55 is incorporated in a case (not shown). There is a problem. Further, since the flatness of the upper and lower surfaces of the laminated piezoelectric element 55 is impaired, for example,
When a multilayer piezoelectric actuator is constructed by stacking a plurality of multilayer piezoelectric elements 55, the stacked (bonded) state becomes unstable and cannot be reliably fixed, or the multilayer piezoelectric actuator is used as a multilayer piezoelectric actuator. In this case, there is a problem that destruction may occur due to external force.

On the other hand, in order to solve the above problems, by laminating the upper and lower surfaces of the laminated body 53, the laminated body 5
External electrodes 54a, 54b that have wrapped around to the upper and lower surfaces of No. 3
However, there is a problem in that the laminate 53 is cracked or chipped during the lapping process.

Further, as shown in FIG. 5B, when the thicknesses (heights) of the external electrodes 54a and 54b that wrap around the upper and lower surfaces are different from each other on the left and right sides, by wrapping them,
Since the upper and lower surfaces of the laminated body 53 are inclined as shown in FIG. 7 and the shape of the laminated body 53 is not a rectangular parallelepiped, there is a problem that predetermined characteristics cannot be obtained.

Therefore, as shown in FIG. 8, the piezoelectric body portion (piezoelectric layer) 51a above the uppermost internal electrode 52a of the laminated body 53 and the piezoelectric body portion 51b below the lowermost internal electrode 52b. By increasing the thickness (that is, by providing dummy layers (piezoelectric layers) 51a and 51b having a large thickness and having no internal electrodes on the upper and lower surfaces) of the external electrode 54 on the laminated body 53. There has been proposed a laminated piezoelectric element 55 which is adapted to prevent it from wrapping around on the lower surface.

However, in this laminated piezoelectric element 55 (FIG. 8), since the dummy layers 51a and 51b are thick, the element thickness (height) required to obtain a predetermined displacement is correspondingly thick. There is a problem of (higher).

The present invention solves the above-mentioned problems, and easily and reliably prevents external electrodes from wrapping around the upper and lower surfaces of a laminate without providing dummy layers or the like. It is an object of the present invention to provide a method for manufacturing a laminated piezoelectric element, which is capable of ensuring the flatness of the element, and does not require a particularly large element thickness or a lapping step.

[0012]

In order to achieve the above-mentioned object, a method of manufacturing a laminated piezoelectric element according to the present invention comprises a plurality of piezoelectric layers, internal electrodes arranged between the piezoelectric layers, and internal layers. In a method of manufacturing a laminated piezoelectric element including an external electrode formed on a side surface from which an electrode is drawn out, a material for forming an external electrode is repelled on upper and lower surfaces of a laminated body of a piezoelectric layer and an internal electrode. The external electrode may be formed by attaching a material for forming an external electrode to a side surface from which the internal electrode is drawn out in a state where the substance is applied.

As the substance repelling the external electrode forming material, for example, a silicone resin can be used. Further, as the substance that repels the external electrode forming material, it is preferable to use a substance capable of burning off at least most of it by heat treatment.

[0014]

Since the substance repelling the external electrode forming material is applied to the upper and lower surfaces of the laminate, the external electrode forming material is applied to the side surface of the laminate by, for example, a method of applying a conductive paste or a dipping method. When the material is attached, the external electrode forming material does not wrap around to the upper and lower surfaces of the laminate. Therefore, it is possible to easily and reliably manufacture a laminated piezoelectric element in which the external electrodes are formed only on the side surfaces and the upper and lower surfaces are flat, without providing a dummy layer or a lapping step. become able to.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1, 2 and 3 are views showing a method of manufacturing a laminated piezoelectric element according to an embodiment of the present invention, and FIG. 4 is a method of manufacturing a laminated piezoelectric element according to an embodiment of the present invention. It is a figure which shows the laminated type piezoelectric element manufactured.

First, the laminated piezoelectric element 5 (FIG. 4) manufactured by the method of this embodiment will be described. The laminated piezoelectric element 5 includes a plurality of laminated piezoelectric layers (eg, piezoelectric layers made of lead zirconate titanate-based material) 1
And internal electrodes 2a, 2b which are arranged between a plurality of piezoelectric layers 1 and are drawn out to two side surfaces facing each other every other layer.
And a laminated body 3 including the piezoelectric layer 1 and the internal electrodes 2a and 2b
Two external electrodes 4 that are electrically connected to the internal electrodes 2a and 2b of the same pole that are drawn out to the two side surfaces 3c and 3d that face each other.
a and 4b, and upper and lower surfaces 3 thereof
a and 3b are formed flat. The external electrode 4
Thick film electrodes are used as a and 4b in consideration of certainty of conduction with the internal electrodes 2a and 2b.

Next, a method of manufacturing the above-mentioned laminated piezoelectric element 5 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 the sheet. It is formed into a shape and punched into a predetermined shape. Then, the internal electrodes are printed on it.

Then, the piezoelectric layers on which the internal electrodes are printed are laminated and pressure-bonded, degreased, and then main firing is performed to obtain a firing unit (laminate unit).

Next, as shown in FIG. 1, the firing unit 1
Silicone resin 12 is applied to the upper and lower surfaces of 1 and cut into a predetermined shape (that is, the shape of the laminated piezoelectric element) to obtain a laminated body 3 as shown in FIG.

Then, as shown in FIG. 3, external electrode forming materials 14a and 14b are attached to the side surfaces 3c and 3d of the laminate 3 by, for example, a method of applying a conductive paste or a method such as dipping. At this time, since the silicone resin 12 is applied to the upper and lower surfaces 3a and 3b of the laminated body 3, the external electrode forming materials 14a and 14b are repelled by the silicone resin 12 and the upper and lower surfaces 3 of the laminated body 3.
It does not go around to a and 3b.

Next, the external electrode forming materials 14a, 14
The laminated body 3 to which b is attached has a predetermined temperature (for example, 300 ° C.).
The external electrode forming material 14 is heat-treated at the above temperature).
a and 14b are baked together with the silicone resin 12
By burning away the side surface 3 as shown in FIG.
External electrodes 4a and 4b are formed only on c and 3d, and a laminated piezoelectric element 5 having flat upper and lower surfaces 3a and 3b can be obtained.

The laminated piezoelectric element 5 manufactured by the method of the above embodiment has no portions (such as external electrodes adhered to the upper and lower surfaces) which may be an obstacle when incorporated in the case. It will be possible to reliably incorporate,
It is possible to manufacture a highly reliable multilayer piezoelectric actuator having predetermined characteristics.

Further, since the laminated piezoelectric element manufactured by the method for manufacturing a laminated piezoelectric element of the present invention is excellent in flatness of the upper and lower surfaces, a plurality of laminated piezoelectric elements are stacked and laminated. Type piezoelectric actuator,
It is possible to obtain a laminated piezoelectric actuator that has excellent stacking (bonding) stability, is not broken by an external force, and has high reliability.

In the above embodiments, the case where the silicone resin is used as the material for repelling the external electrode forming material has been described. This silicone resin is a substance (resin) that can be suitably used as a substance that repels a normal external electrode forming material, but the substance that repels the external electrode forming material is not necessarily limited to the silicone resin. Instead, it is possible to use various other substances in consideration of the type of external electrode forming material. As the material for repelling the external electrode forming material, it is preferable to use a material capable of burning off at least most of it by heat treatment, such as the above-mentioned silicone resin.

The present invention is not limited to the above-mentioned embodiments in other respects, and the kind and composition of the material forming the piezoelectric layer, the specific shape of the piezoelectric layer, the laminating method, the internal structure, etc. Various applications and modifications can be made within the scope of the invention with respect to the constituent materials of the electrodes and the external electrodes and the forming method thereof.

[0027]

As described above, according to the method of manufacturing a laminated piezoelectric element of the present invention, a substance repelling the external electrode forming material is applied to the upper and lower surfaces of the laminated body of the piezoelectric layer and the internal electrode. In this state, the external electrodes are formed by adhering the external electrode forming material to the side surfaces from which the internal electrodes are drawn out, so that the upper and lower surfaces of the laminated body can be formed without providing dummy layers or the like. It is possible to easily and reliably manufacture the laminated piezoelectric element having the flat upper and lower surfaces by preventing the external electrodes from wrapping around.

Further, according to the method of manufacturing a laminated piezoelectric element of the present invention, it is not necessary to provide a lapping step or the like for flattening the upper and lower surfaces, and the manufacturing step is simplified and the lapping is performed. It is possible to prevent the occurrence of cracks and chips during the process.

Further, since the laminated piezoelectric element manufactured by the manufacturing method of the present invention is not provided with a dummy layer or the like, the element thickness (height) can be reduced accordingly.

[Brief description of drawings]

FIG. 1 is a perspective view showing a state in which a silicone resin is applied to the upper and lower surfaces of a firing unit formed in one step of a method of manufacturing a laminated piezoelectric element according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a laminated body in which a silicone resin is applied to the upper and lower surfaces, which is formed in one step of the method for manufacturing a laminated piezoelectric element according to the embodiment of the present invention.

FIG. 3 is a side view of a laminated body in which a substance (silicone resin) that repels an external electrode forming material is applied to the upper and lower surfaces in one step of the method for manufacturing a laminated piezoelectric element according to an embodiment of the present invention. It is sectional drawing which shows the state which the external electrode formation material was made to adhere.

FIG. 4 is a cross-sectional view showing a laminated piezoelectric element manufactured by a method for manufacturing a laminated piezoelectric element according to an embodiment of the present invention.

FIG. 5 is a view showing a conventional laminated piezoelectric element,
(A) is a perspective view and (b) is a sectional view.

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

FIG. 7 is a cross-sectional view showing a conventional laminated piezoelectric element whose upper and lower surfaces are wrapped.

FIG. 8 is a dummy layer (piezoelectric layer) having a large thickness on the upper and lower surfaces.
FIG. 10 is a cross-sectional view showing a conventional laminated piezoelectric element provided with.

[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 5 Laminated piezoelectric element 11 Firing unit 12 Silicone resin 14a, 14b External electrode Forming material

Claims (1)

[Claims] 1. A method for manufacturing a laminated piezoelectric element, comprising: a plurality of piezoelectric layers; internal electrodes arranged between the piezoelectric layers; and external electrodes formed on side surfaces from which the internal electrodes are drawn out. In a state where a substance repelling the external electrode forming material is applied to the upper and lower surfaces of the laminated body of the piezoelectric layer and the internal electrode, the external electrode forming material is attached to the side surface from which the internal electrode is drawn out. A method for manufacturing a laminated piezoelectric element, which comprises forming external electrodes by using