JPH0828539B2 - Electrostrictive effect element - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrostrictive effect element used in a piezoelectric actuator.

[Conventional technology]

A conventional method for manufacturing this type of electrostrictive effect element will be described.

First, an organic binder is mixed with a multi-component solid solution ceramic powder having a perovskite crystal structure to form a green sheet, and a silver electrode conductor layer is applied as a paste on the green sheet, and then dozens of layers (for example, 64 layers) are laminated. Be flexed. All the ends of the silver electrode conductor layer are exposed on the side surface of this flexible body, and in order to form a comb-shaped internal electrode, the ends of the silver electrode conductor layer are insulated on every other side by one layer. For the other side surface, the end portion of the silver electrode conductor layer on which the insulating layer is not formed is insulated. Then, the silver electrode conductor layers are alternately connected to form two interdigital internal electrodes. After the lead wire 5 is soldered to the laminate 1 having the electrostrictive effect thus obtained, the electrically insulating resin 3 is formed. In this way, the electrostrictive effect element as shown in FIG. 2 is obtained.

This electrostrictive effect element has a structure in which a moisture-proof resin is applied only to the side surface, not to the upper surface and the lower surface, and the interface between the side surface of the element and the resin is exposed on the surface. Therefore, moisture easily penetrates this interface and enters the element surface, and the element has a full-surface electrode structure, and the internal electrodes are exposed on the surface at intervals of several tens to 100 μm. There is a drawback that the withstand voltage of the element is significantly reduced due to the ingress of moisture as shown in (3), and when the entire surface is covered with resin to prevent the exposure of the interface between the side surface of the element and the resin, the elasticity of the resin causes However, the resin applied to the upper and lower surfaces absorbs the displacement of the element, and it is not possible to take out sufficient displacement. In order to prevent the interface between the side surface of the element and the resin from being exposed, as shown in FIG. 3, there is an electrostrictive effect element in which a thin metal plate 6 is fixed to the upper and lower end surfaces of the element instead of the resin.

[Problems to be Solved by the Invention]

The above-mentioned conventional electrostrictive effect element (FIG. 3) has the following drawbacks.

(1) There is a drop in displacement between the central portion and the peripheral portion of the element, and the thin metal plate fixed to the upper and lower end faces is deformed by this drop, and when repeatedly displaced, the thin metal plate peels off. , There is a drawback in life.

(2) Also, by fixing a thin metal plate to the end surface,
Although it has a structure that prevents the interface between the side surface and the resin from being exposed, it cannot be said to be sufficient because it can take only the thickness of the electrically insulating resin when viewed from the moisture penetration distance at the interface.

(3) Furthermore, since the lead wire is soldered directly to the element, a twisting or bending force is applied to the lead wire during handling, resulting in disconnection, or repair of a lead wire that has been disconnected. It has the drawback of being difficult.

[Means for solving the problem]

The electrostrictive effect element of the present invention is an electrostrictive effect element including a laminated body in which a piezoelectric ceramic member and an internal electrode conductor are alternately laminated, and a pair of lead terminals are provided on the external electrode conductor of the laminated body, In a state in which a part of the lead terminal is projected, the four side surfaces of the laminated body where the internal electrode conductor layers are exposed are coated with an electrically insulating resin. A cap-shaped thin metal plate is fixed to the end face.

[Action]

By forming a thin metal plate that adheres to the upper and lower end faces of the element into a cap shape, the thin metal plate adheres not only to the end faces but also to the side faces, so the thin metal plate peels off even when repeatedly displaced. Never. Further, regarding the distance of moisture ingress at the interface, a cap-like shape can provide a sufficient distance. In addition, when taking out the lead wire, instead of directly taking the lead wire from the element, take out from the element with the lead terminal and attach the lead wire to the lead terminal But it is easy to repair.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a vertical sectional view of a first embodiment of the electrostrictive effect element of the present invention.

The electrostrictive effect element according to the present embodiment includes a laminated body 1 in which a piezoelectric ceramic member and an internal electrode conductor are laminated, a pair of lead terminals 2 is provided on the external electrode conductor of the laminated body 1, and one of the lead terminals 2 is provided. With the projecting portion, the four side surfaces of the laminated body 1 where the internal electrode conductor layers are exposed are covered with the electrically insulating resin 3, and the upper and lower end surfaces of the electrostrictive effect element including the resin 3 are cap-shaped. The thin plate 4 is fixed.

Next, a method of assembling this electrostrictive effect element will be described.

After soldering the lead terminals 2 to the laminated body 1 produced by the same method as the conventional method, the laminated body 1 is attached to a resin casting jig, epoxy resin is injected, and 170 ° C-1
The resin 3 is cured under the condition of time to form the electrically insulating resin 3. Subsequently, the laminated body 1 on which the electrically insulating resin 3 is formed
Thickness 0.08mm with epoxy adhesive applied on the top and bottom edges
The cap-shaped stainless steel thin plate 4 is attached, and while being pressed by a jig, it is cured and adhered under the condition of 150 ° C.-30 minutes. By the above, the electrostrictive effect element shown in FIG. 1 is obtained.

 Next, a second embodiment will be described.

The second embodiment is different from the first embodiment in that the laminated body 1
A thin metal plate in the shape of a cap that adheres to the upper and lower end surfaces of the
The point is that a thin 0.08 mm phosphor bronze plate is used.

In the present embodiment, phosphor bronze is used as the cap-shaped thin metal plate, but when the plate thickness is the same, phosphor bronze has a smaller spring constant than stainless steel, so that the difference in displacement is large. In that case, there are advantages.

〔The invention's effect〕

As described above, the present invention has a cap-shaped thin metal plate that is fixed to the upper and lower end surfaces of the electrostrictive effect element containing the electrically insulating resin, so that the thin metal plate is not only the end surface of the element, Since it is also fixed to the side surface, when repeatedly displaced, the metal thin plate peeled off after repeated displacement of 100,000 times or more. Peeling did not occur, and as a result of the increased moisture penetration distance at the interface, the DC moisture resistance load life was 2500 to 3000 hours in the past, but 4000 hours or more, sufficient reliability was obtained, When the wire was directly soldered to the element, there were many failures that could not be repaired due to breakage of the lead, but by using the lead terminal, even if the lead wire is broken, it is possible to repair it.
It has the effect of improving the yield.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of a first embodiment of an electrostrictive effect element of the present invention, and FIGS. 2 and 3 are vertical sectional views showing a conventional electrostrictive element. 1 ... Laminated body, 2 ... Lead terminal, 3 ... Electrically insulating resin, 4 ... Cap-shaped stainless steel thin plate.

Claims (1)

[Claims] 1. An electrostrictive effect element including a laminated body in which a piezoelectric ceramic member and an internal electrode conductor are alternately laminated, wherein a pair of external electrode conductors are provided on side surfaces of the laminated body along a laminating direction. A lead terminal is provided, the entire side surface except the upper and lower end surfaces of the laminate is covered with an electrically insulating resin, and a part of the lead terminal is projected from the resin, and a cap-shaped thin metal plate is further provided on the laminate. An electrostrictive effect element, characterized in that the cap-shaped thin metal plate is fixed to the upper and lower end faces and is also fixed to the resin so as to cover a region near the upper and lower end faces of the resin.