JP3006355B2 - Manufacturing method of laminated piezoelectric element - Google Patents

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

[0002]

2. Description of the Related Art As a laminated piezoelectric actuator using a piezoelectric material, for example, as shown in FIGS. The internal electrode 52 having the partial electrode structure is provided, and the laminated body 53 composed of the piezoelectric layer 51 and the internal electrode 52 is electrically connected to the internal electrode of the same polarity on the side surface from which the internal electrode 52 is drawn out (ie, There has been proposed a multilayer piezoelectric actuator having a structure in which a multilayer piezoelectric element 55 provided with external electrodes 54 (in which internal electrodes of the same polarity are connected in parallel) is housed in a case (not shown).

In the above-mentioned laminated piezoelectric element 55, the internal electrodes 52 are alternately alternately connected to the external electrodes 54 (FIG. 5) on the opposite side, as shown in FIG. It is pulled out to the opposite end.

The external electrodes 54 include the internal electrodes 5.
A thick-film electrode is used in consideration of the reliability of conduction with the second electrode.

By the way, the above-mentioned conventional laminated piezoelectric element 5
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 laminate 53, The upper end 54a and the lower end 54b of the external electrode 54 are connected so that the connection between the external electrode 54 and the uppermost and lowermost internal electrodes 52 drawn to the side surfaces of the external electrode 54 can be reliably performed.
However, the external electrodes 54 are formed so as to extend from the corners (edges) of the laminate 53 to the upper and lower surfaces thereof.

For this reason, the portions 54a and 54b of the external electrode 54 that extend to the upper and lower surfaces of the multilayer body 53 become obstacles when the multilayer piezoelectric element 55 is assembled in a case (not shown). There is a problem. Further, since the flatness of the upper and lower surfaces of the multilayer piezoelectric element 55 is impaired, for example,
When a multilayer piezoelectric actuator is formed by stacking a plurality of multilayer piezoelectric elements 55, the stacked (joined) state becomes unstable and cannot be reliably fixed or used as a multilayer piezoelectric actuator. In such a case, there is a problem that destruction is caused by an external force.

On the other hand, in order to solve the above-mentioned problem, the upper and lower surfaces of the laminate 53 are wrapped so that the laminate 5
3. External electrodes 54a and 54b extending to the upper and lower surfaces of 3
However, there is a problem that cracks or chips occur in the laminate 53 in the lapping process.

As shown in FIG. 5 (b), when the thickness (height) of the external electrodes 54a, 54b extending to the upper and lower surfaces is different on the left and right, the outer electrodes 54a, 54b are wrapped.
As shown in FIG. 7, the upper and lower surfaces of the stacked body 53 are inclined, and the shape of the stacked body 53 is not a rectangular parallelepiped. Therefore, there is a problem that predetermined characteristics cannot be obtained.

Therefore, as shown in FIG. 8, a piezoelectric portion (piezoelectric layer) 51a above the uppermost internal electrode 52a of the laminated body 53 and a piezoelectric portion 51b below the lowermost internal electrode 52b. (That is, dummy layers (piezoelectric layers) 51a and 51b having a large thickness and no internal electrodes are provided on the upper and lower surfaces) so that the external electrodes 54 There has been proposed a laminated piezoelectric element 55 that is prevented from wrapping around the lower surface.

However, in the laminated piezoelectric element 55 (FIG. 8), since the thickness of the dummy layers 51a and 51b is large, the element thickness (height) required to obtain a predetermined displacement is increased by that much. (High).

The present invention has been made to solve the above-mentioned problems, and it is possible to easily and surely prevent external electrodes from going around the upper and lower surfaces of a laminated body without providing a dummy layer or the like. It is an object of the present invention to provide a method of manufacturing a laminated piezoelectric element which can ensure the flatness of the piezoelectric element and does not need to particularly increase the element thickness or provide a lapping step.

[0012]

In order to achieve the above object, a method for manufacturing a laminated piezoelectric element according to the present invention comprises a plurality of piezoelectric layers, an internal electrode disposed between the piezoelectric layers, and an internal electrode. In a method for manufacturing a laminated piezoelectric element including an external electrode formed on a side surface from which an electrode is drawn, a material for forming an external electrode is repelled on upper and lower surfaces of a laminate of a piezoelectric layer and an internal electrode. In a state where the substance is applied, an external electrode forming material is attached to a side surface from which the internal electrode is drawn out to form an external electrode.

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

[0014]

The material for repelling the material for forming an external electrode is applied to the upper and lower surfaces of the laminate. Therefore, the material for forming the external electrode is coated on the side surface of the laminate by, for example, applying a conductive paste or dipping. In this case, the material for forming an external electrode does not reach the upper and lower surfaces of the laminate. Therefore, it is not necessary to provide a dummy layer or a lapping step, and it is possible to easily and reliably manufacture a laminated piezoelectric element in which external electrodes are formed only on the side surfaces and the upper and lower surfaces are flat. become able to.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1, 2 and 3 show a method of manufacturing a laminated piezoelectric element according to an embodiment of the present invention. FIG. 4 shows a method of manufacturing a laminated piezoelectric element according to an embodiment of the present invention. FIG. 3 is a view showing a laminated piezoelectric element that has been 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 (for example, a piezoelectric layer made of a lead zirconate titanate-based material) 1
And internal electrodes 2a, 2b disposed between the plurality of piezoelectric layers 1 and drawn out to two side surfaces facing each other.
And a laminate 3 composed of 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 polarity that are drawn out to the two opposing side surfaces 3c and 3d.
a, 4b, and upper and lower surfaces 3
a and 3b are formed flat. The external electrode 4
Thick film electrodes are used as a and 4b in consideration of the reliability 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), the raw materials are weighed, pulverized, mixed with a binder, defoamed, and then removed from the sheet. It is formed into a shape and punched into a predetermined shape. Then the internal electrodes are printed on this.

Then, the piezoelectric layers on which the internal electrodes are printed are laminated and press-bonded, degreased, and then main-baked to obtain a fired unit (laminated unit).

Next, as shown in FIG.
After applying the silicone resin 12 to the upper and lower surfaces of the piezoelectric element 1, the laminate is 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, the external electrode forming materials 14a and 14b are adhered to the side surfaces 3c and 3d of the laminate 3 by, for example, a method of applying a conductive paste or dipping. At this time, since the silicone resin 12 is applied to the upper and lower surfaces 3a and 3b of the laminate 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 laminate 3 are formed.
It does not go to a and 3b.

Next, the external electrode forming materials 14a, 14
b at a predetermined temperature (for example, 300 ° C.).
Heat at the above temperature) to form the external electrode forming material 14.
a and 14b, and the silicone resin 12
Of 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 attached to the upper and lower surfaces) that may hinder the incorporation into the case. It becomes possible to incorporate reliably,
It is possible to manufacture a highly reliable laminated piezoelectric actuator having predetermined characteristics.

Further, since the multilayer piezoelectric element manufactured by the method of manufacturing a multilayer piezoelectric element of the present invention has excellent flatness of the upper and lower surfaces, a plurality of multilayer piezoelectric elements are stacked and stacked. When configuring a piezoelectric actuator,
It is possible to obtain a highly reliable laminated piezoelectric actuator which is excellent in stacking (joining) stability, does not break due to external force, and is highly reliable.

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

The present invention is not limited to the above-described embodiment in other respects. The type and composition of the material constituting the piezoelectric layer, the specific shape of the piezoelectric layer, the lamination method, and the internal Various applications and modifications can be made to the constituent materials of the electrodes and the external electrodes and the method of forming the same within the scope of the invention.

[0027]

As described above, according to the method of manufacturing a laminated piezoelectric element of the present invention, a material for repelling a material for forming an external electrode is applied to the upper and lower surfaces of a laminate of a piezoelectric layer and an internal electrode. In this state, the external electrodes are formed by attaching an external electrode forming material to the side surfaces from which the internal electrodes are drawn, so that the upper and lower surfaces of the laminate are not provided without providing a dummy layer or the like. Thus, it is possible to easily and reliably manufacture a laminated piezoelectric element having 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. It is possible to prevent cracks and chips from occurring in the process and the like.

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

[Brief description of the drawings]

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

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

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, (b) is a sectional view.

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

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

FIG. 8 shows a thick dummy layer (piezoelectric layer) on the upper and lower surfaces.
FIG. 4 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 / lower surface of laminated body 3c, 3d Laminated body side 4a, 4b External electrode 5 Laminated piezoelectric element 11 Firing unit 12 Silicone resin 14a, 14b External electrode Forming material

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 41/22 H01L 41/083

Claims (1)

(57) [Claims] 1. A method of manufacturing a laminated piezoelectric element comprising: a plurality of piezoelectric layers; internal electrodes disposed between the piezoelectric layers; and external electrodes formed on side surfaces from which the internal electrodes are drawn. In a state where a substance repelling an external electrode forming material is applied to the upper and lower surfaces of a laminate of a piezoelectric layer and an internal electrode, an external electrode forming material is attached to a side surface from which the internal electrode is drawn. Forming a multi-layer piezoelectric element by forming an external electrode.