JPH0786654A - Laminated electric / strain conversion element, laminated ceramic actuator and manufacturing method thereof - Google Patents

Abstract

(57) [Abstract] [Purpose] By enabling chemical bonding between the insulating coating resin and the ceramics, the adhesive strength is high, voids are less likely to occur, and short circuits and creeping discharges are reliably prevented. [Structure] A plurality of ceramic piezoelectric bodies 1 having electrodes 2 and 2'formed on the front and back surfaces are laminated and bonded via an external electrode 3 to manufacture a laminated body. After immersing this laminate in a solution of a silane coupling agent in ethanol,
Dry in a dryer. Thereafter, the entire surface of this laminate is coated with the insulating coating resin 10. Every other external electrode 3 projecting outward from the resin 10 is connected with lead wires 4 and 5 so as to have the same potential, and thus the laminated electric / strain conversion element 11 is configured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated electric / strain conversion element that expands and contracts according to an applied voltage, a laminated ceramic actuator and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, in precision positioning devices such as optical or magnetic disk heads, various optical devices, precision machine tools, etc., for example, Japanese Patent Laid-Open No. 63-136581 "Layered Piezoelectric Body", Japanese Patent Publication No. 63-17354. As disclosed in the publication “Electrostrictive effect element” and the like, a large number of piezoelectric elements are formed by stacking, and the piezoelectric elements are expanded and contracted according to an applied voltage to be used as a micro-driving actuator. There is.

FIG. 2 is a cross-sectional view showing the basic structure of such a laminated electric / strain conversion element. A plurality of thin-film ceramic piezoelectric bodies (ceramic elements) having electrodes 2 and 2'on the front and back surfaces are formed. ) 1 is laminated and adhered via external electrodes 3 made of a copper metal plate or the like, and every other external electrode 3 is connected to a power source via lead wires 4 and 5 so as to have the same electric potential, and thereby each ceramic Piezoelectric bodies 1 are electrically connected in parallel to form a laminated electric / strain conversion element 6, and a high voltage (eg, 1 KV / mm or more) is applied to this to generate strain in each ceramic piezoelectric body 1. On the contrary, when an external force is applied to cause deformation, an electric charge is generated on the surface of the piezoelectric body in proportion to the external force to generate a voltage. This property is called piezoelectric. In FIG. 2, 7 is an insulator.

[0004]

In such a laminated type electric / strain conversion element, when a large displacement is applied to a ceramic material composed of a piezoelectric element or an electrostrictive element, a large displacement of 1 KV / mm or more is applied to both ends of the element. It is necessary to apply an electric field, and if water or conductive dust adheres to the side surface of the ceramic material to which the large electric field is applied, there is a problem that short-circuiting or creeping discharge easily occurs and the reliability is significantly reduced.
That is, normally, silver, nickel, etc. are used as the electrode film of the ceramic material, but if there is a little moisture,
On the side surface of the material to which an electric field is applied, metal ions are generated from the positive electrode, which are electrically attracted to receive electrons at the negative electrode to deposit metal. This phenomenon is called migration. When the migration occurs, the distance between the electrodes becomes shorter and the insulating property deteriorates. As a result, short circuits and creeping discharges easily occur. In addition, if there is a void in the portion where migration has occurred, short circuit and creeping discharge are particularly likely to occur.

Therefore, as a countermeasure, for example, a method of covering with an insulating resin or grease or the like to prevent the ingress of moisture from the outside, a gap between the ceramic piezoelectric elements and a viscous insulating material on the side surfaces of the ceramic piezoelectric elements. (Japanese Patent Application Laid-Open No. 63-136581), the insulating material is applied to the end faces of the internal electrodes on one side surface of the laminated chip every other layer, and then the conductive material to be the one electrode is formed. Then, on the other side, a method of forming a conductive substance to be the other electrode from the one side where the insulating substance is not applied on the one side face is coated with the insulating substance on every other end face of the internal electrode plate (the above-mentioned special feature). Kosho 63-173
No. 54) is proposed and implemented.

However, the above-mentioned method has a drawback that the interface between the resin, which is an organic substance, and the ceramic, which is an inorganic substance, is difficult to chemically bond, so that the adhesive strength is weak and voids are easily formed. On the other hand, all of the above methods have a problem that a high positioning accuracy is required and the work is troublesome because it is necessary to partially coat and form the insulating material on the side surface of the thin piezoelectric element.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to make it possible to chemically bond an insulating coating resin and ceramics to improve the adhesive strength. It is an object of the present invention to provide a laminated electric / strain conversion element, a laminated ceramic actuator, and a method for manufacturing the same, which are large and are less likely to cause voids and can reliably prevent short-circuiting and creeping discharge.

[0008]

In order to achieve the above object, a laminated electric / strain conversion element according to the first invention comprises a plurality of piezoelectric or electrostrictive materials having electrodes formed on the front and back surfaces. Multi-layer type with ceramic materials laminated and bonded
In the strain conversion element, the outer surface of the ceramic material is subjected to silane coupling treatment and coated with an insulating coating resin. A laminated ceramic actuator according to the second invention uses the laminated electric / strain conversion element according to the first invention. A method of manufacturing a laminated electric / strain conversion element according to a third aspect of the present invention includes a step of laminating and bonding a plurality of ceramic materials made of a piezoelectric material or an electrostrictive material having electrodes formed on the front and back surfaces, and the laminating and bonding. And a step of subjecting the outer surface of the ceramic material to a silane coupling treatment, and a step of coating the outer surface of the ceramic material with an insulating coating resin after the silane coupling treatment.

[0009]

In the present invention, the silane coupling treatment can connect the interface between the ceramic material, which is an inorganic material, and the insulating coating resin, which is an organic material, by a chemical bond. Therefore, the adhesive strength is high, and the generation of voids that cause a short circuit or a creeping discharge is prevented. The silane coupling treatment may be carried out by immersing the laminated type electrical / strain conversion element in a silane coupling agent dissolved in a suitable solvent for a required time, drying after the immersion, and then coating the insulating coating agent by a usual treatment. The insulating coating resin prevents adhesion of water, conductive dust, and the like.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a laminated electric / strain conversion element according to the present invention. In addition, in FIG.
Components that are the same as those in FIG. Further, the thickness and size of each part in the drawing are exaggerated for ease of understanding, and are different from actual dimensions. In this embodiment, a plurality of thin-film ceramic piezoelectric bodies 1 made of lead zirconate titanate-based piezoelectric material and having electrodes 2 and 2 ′ formed on the front and back surfaces are used as an external electrode 3 made of a copper metal plate or the like. Then, the laminate is immersed in a solution in which a silane coupling agent is dissolved in ethanol, and then dried in a drier at 120 ° C. Then, the entire surface of the laminate is covered with an acrylic resin or the like. Insulating coating resin 10 is coated with a resin having a thickness of 0.5 mm by a normal process to obtain a resin 1
The laminated type electric / strain conversion element 11 is manufactured by connecting every other external electrode 3 protruding from 0 to the same potential so as to have the same potential. Then, the laminated electric / strain conversion element 11 having such a configuration is expanded and contracted by applying a high voltage between the electrodes 2 and 2 ′ of each ceramic piezoelectric body 1 connected to a power source, and the movable part of the device is moved. Used as a micro-actuated multilayer ceramic actuator. Reference numeral 12 is an outer surface portion of each ceramic piezoelectric body 1 that has been subjected to the silane coupling treatment.

When the outer surface of the ceramic piezoelectric body 1 is subjected to the silane coupling treatment as described above, the interface between the ceramic piezoelectric body 1 which is an inorganic substance and the insulating coating resin 10 which is an organic substance can be chemically bonded. Therefore, as compared with the case where the insulating coating resin is simply coated without performing the silane coupling treatment, the adhesive strength is high and the generation of voids can be prevented.

The laminated electric / strain conversion element 11 having the above structure was placed in a constant temperature oven to set an atmosphere of 90% at 40 ° C. In addition, this element 11 is 1300 V / mm
The electric field was applied and the time until discharge was measured. As a comparative example, it is listed in Table 1 together with the results of the laminated electric / strain conversion element not subjected to the silane coupling treatment.

[0013]

[Table 1]

As is apparent from Table 1, the laminated type electrical / strain conversion element 1 according to the present invention which has been subjected to the silane coupling treatment.
It can be seen that in No. 1, the time until discharge is longer than that in the case without treatment.

In the above embodiment, the external electrode 3 is formed of a metal plate made of copper, but the invention is not limited to this. Silver paste is applied and fired along the side surface of the ceramic piezoelectric body 1 to form the external electrode. It may be

[0016]

As described above, in the laminated electric / strain conversion element according to the present invention, the outer surface of the ceramic material is coated with the insulating coating resin after the silane coupling treatment,
The element and the resin can be chemically bonded to each other, and the adhesive strength can be increased. Further, due to the chemical bonding, no void is generated, short circuit and creeping discharge can be prevented, and the reliability and durability of the device can be improved. Also,
In the silane coupling treatment, the element may be dipped in a silane coupling liquid for a required time and then dried. Therefore, the work is simple and the troublesome positioning work is not required, and the productivity can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a laminated electric / strain conversion element according to the present invention.

FIG. 2 is a cross-sectional view showing the basic structure of a conventional laminated electric / strain conversion element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic piezoelectric body 2, 2'internal electrode 3 External electrode 4 Lead wire 5 Lead wire 6 Laminated electric / strain conversion element 10 Insulation coating resin 11 Laminated electric / strain conversion element 12 Silane-coupling treated outer surface

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kenichi Muramatsu 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (3)

[Claims] 1. A laminated electric / strain conversion element in which a plurality of ceramic materials made of a piezoelectric material or an electrostrictive material having electrodes formed on the front and back surfaces are laminated and adhered, and the outer surface of the ceramic material is a silane coupling treatment. A laminated type electric / strain conversion element characterized by being coated with an insulating coating resin. 2. A multilayer ceramic actuator using the multilayer electric / strain conversion element according to claim 1. 3. A step of laminating and adhering a plurality of ceramic materials made of a piezoelectric material or an electrostrictive material having electrodes formed on the front and back surfaces, and a silane coupling treatment on the outer surfaces of the laminated and adhering ceramic materials. A method of manufacturing a laminated electric / strain conversion element, comprising: a step of coating the outer surface of the ceramic material with an insulating coating resin after a silane coupling treatment.