JPH0366822B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method of manufacturing a laminated piezoelectric element used in a piezoelectric actuator, etc. More specifically, the present invention relates to a method of manufacturing a laminated piezoelectric element used in a piezoelectric actuator, etc. The present invention relates to a method for manufacturing a laminated piezoelectric element in which internal electrodes are exposed by removing provided insulators at predetermined positions to establish electrical connections between the internal electrodes.

[Prior Art] Piezoelectric actuators are used to perform minute displacements in manufacturing equipment for various electronic components such as semiconductors that require microfabrication, and in optical devices that require minute positioning.

There are two methods for manufacturing the laminated piezoelectric elements used in such piezoelectric actuators: one is to bond together a large number of sintered piezoelectric ceramic plates, and the other is to laminate unsintered sheets and then sinter them together. be.

The former lamination adhesion method, for example, as shown in FIG. After applying adhesive to each sheet of metal terminal plates 12 made by etching or the like to have the same dimensions, aligning the direction of the metal terminals 12a, and laminating tens to hundreds of them, the corresponding two sets of metal terminals 12a are bonded together.
This is a method of assembling the parts by connecting them with lead wires 14.

On the other hand, the latter integral sintering method is a method in which internal electrodes are printed on an unsintered sheet of piezoelectric ceramic, the sheets are laminated and pressure-bonded, integrally sintered, and external electrodes are formed after cutting to a predetermined size. For example, as shown in FIG. 3, internal electrodes 16 such as platinum are interposed between piezoelectric ceramic plates 10, and an insulating material 18 such as glass is coated on the side surfaces of every other layer of the internal electrodes, and external electrodes 20 is applied.

[Problems to be Solved by the Invention] However, the former method using lamination and adhesion is extremely cumbersome because piezoelectric ceramic plates of a predetermined shape and metal terminal plates must be laminated with their terminal directions aligned. It has the disadvantage that it is not suitable for mass production and cannot be lowered in price.

On the other hand, the latter method of integral sintering has the advantage that a large number of piezoelectric laminates can be cut out by one lamination, which saves the labor of lamination work. However, the sintering temperature of piezoelectric ceramics is as high as 1,200 to 1,300 degrees Celsius, and the composition of ceramics is a lead compound that is highly reactive, which means that the internal electrodes are limited to expensive precious metals such as platinum. Therefore, there is a drawback that the cost required for the electrode material increases. In addition, the platinum internal electrode must be formed over the entire surface of the interlayer to avoid non-uniform strain, and this has a structural defect that limits the ceramic solid phase reaction between the layers and reduces the adhesion strength.

It is an object of the present invention to eliminate the above-mentioned drawbacks of the prior art, to be able to use inexpensive materials for internal electrodes, to be able to cut out a large number of piezoelectric laminates by laminating them once, and to make it possible to cut out a large number of piezoelectric laminates by laminating them once. It is an object of the present invention to provide a method for manufacturing a laminated piezoelectric element, which greatly simplifies the manufacturing process including formation, and can ensure sufficiently high reliability in terms of mechanical strength and the like.

[Means for Solving the Problems] The present invention, which can achieve the above objects, basically adopts a method of laminating and bonding sintered piezoelectric ceramic plates, and forms external electrodes and The connection structure between the electrode and external electrode has been devised,
This is a method of manufacturing a laminated piezoelectric element that has been improved to be suitable for mass production.

That is, in the present invention, a large number of sintered piezoelectric ceramic plates each having a conductive layer formed on the surface thereof to serve as an internal electrode are laminated and bonded together with an adhesive. Usually, a piezoelectric laminate of a predetermined size is obtained by cutting out a block that is bonded and integrated using a large piezoelectric ceramic plate.

Next, the side surfaces of the obtained piezoelectric laminate are covered with an insulating material, and the insulating material corresponding to the internal electrodes on the first side surface is removed every other layer to expose the end surfaces of the internal electrodes, and the second side surface is covered with an insulating material. In this step, the insulating material at the portion corresponding to the internal electrode is removed every other layer while being shifted one layer from the first side surface to expose the end surface of the internal electrode. External electrodes are provided on each of the first and second side surfaces, and each internal electrode is connected to the external electrode on both side surfaces. In this way, a laminated piezoelectric element is manufactured.

[Function] Since the present invention is basically a method of laminating and bonding sintered piezoelectric ceramic plates, inexpensive materials such as silver and nickel can be used for the internal electrodes.
Furthermore, since the internal electrode lead-out structure has been devised, there is no need to sandwich metal terminal plates, and a large number of piezoelectric laminates can be obtained by cutting out a block of predetermined size from a block obtained by a single lamination operation.

In addition, the connection between the internal electrodes and the external electrodes is achieved by removing part of the insulating material provided on the sides of the piezoelectric laminate, instead of attaching an insulating material to a predetermined position of the piezoelectric laminate. Because it is an exposed structure, even if the thickness of the piezoelectric ceramic plate is extremely thin,
Further, even if the number of laminated sheets is extremely large, the work is easy, and the connection between the internal electrodes and the external electrodes can be easily performed.

[Example] FIG. 1 is a process explanatory diagram showing an example of the method of the present invention. First, as shown in FIG. 1A, a large number of sintered piezoelectric ceramic plates 30 each having a conductive layer formed on its surface to serve as an internal electrode 32 are laminated and bonded together with an adhesive. A prototype experiment was conducted using a piezoelectric ceramic plate 30 having dimensions of approximately 50 mm in length, 40 mm in width, and 0.2 mm in thickness. A conductive layer is formed on only one side of the piezoelectric ceramic plates 30 located on the top and bottom surfaces, and on the entire front and back surfaces of the other piezoelectric ceramic plates. This conductive layer can be easily formed by baking silver, for example.
The process of forming silver electrodes on a piezoelectric ceramic plate of this size is similar to the process conventionally used to manufacture elements such as piezoelectric buzzers, and mass production technology has already been established, so it can be manufactured at low cost. Is possible.

For example, epoxy adhesive is screen printed on such piezoelectric ceramic plates 30, several tens to hundreds of sheets are laminated, and the piezoelectric ceramic plates 30 are tightened and cured in a vise. In order to simplify the drawing, only seven piezoelectric ceramic plates are shown in FIG. 1, but in reality, a large number of piezoelectric ceramic plates will be laminated as described above. The height of the stacked blocks becomes a constant value depending on the printing thickness of the adhesive, the sandwiching pressure, etc. This is cut out at the position indicated by the broken line using a cutter using a diamond blade or the like to obtain a piezoelectric laminate 34 as shown in FIG. The dimensions of the piezoelectric laminate 34 are, for example, 5 mm in length and 4 mm in width.
That's about it. The internal electrodes 32 of each layer are exposed on four sides.

Next, as shown in FIG.
A glass plate 36 of about 0.1 mm is adhered with an epoxy adhesive, and the remaining two sides are simply covered with the same epoxy adhesive. Then, using a diamond blade having a thickness of 0.1 mm, cuts 38 with a depth of 150 μm are made at the locations corresponding to the internal electrodes of the glass plate 36 at intervals of 0.4 mm, as shown in FIG. In this case, cutouts 38 are formed every other layer at the locations corresponding to the internal electrodes of the glass plate 36 on one side (left side in the drawing) to expose the end surfaces of the internal electrodes 32, and the opposite side (on the right side in the drawing) is As for the glass plate 36 on the side surface, the internal electrode dimensions are shifted one more distance from the left side surface, and cuts 38 are provided in every other layer to expose the end surfaces of the internal electrodes 32.

Finally, conductive adhesive 40 is used as an external electrode.
is formed on each glass plate 36 by a method such as brush painting or dip coating so as to connect the exposed internal electrodes to obtain a laminated piezoelectric element (see E in the same figure).

The polarization of each piezoelectric ceramic plate 30 is basically carried out when the plate is alone, but in some cases it may be carried out after the piezoelectric ceramic plates 30 are laminated and bonded.

Although a preferred embodiment of the present invention has been described above in detail, the present invention is not limited to only such a configuration. Although the internal electrodes are baked with silver in the above embodiment, it is also possible to form a conductive layer with nickel plating or the like. In some cases, the insulator provided on the side surface of the piezoelectric laminate may be only a resin coating without using a glass plate or the like.
Further, the removal of the insulating material to expose the internal electrodes can be carried out not only by mechanically forming grooves but also by photo-etching or the like.

[Effects of the Invention] As described above, the present invention is configured such that sintered piezoelectric ceramic plates are laminated and bonded, and a part of the insulating material formed on the side surface is removed to expose the internal electrodes and connect them to the external electrodes. This eliminates the need for metal terminal plates, etc.
By laminating and adhering large piezoelectric ceramic plates and cutting them out, it is possible to obtain a large number of piezoelectric laminates at once, which allows for mass production.

Furthermore, since the present invention uses a bonding method using adhesive, the use of a strong structural adhesive increases mechanical strength and improves reliability.Furthermore, inexpensive electrode materials can be used for the internal electrodes. Coupled with the fact that it can be cut out, it has the effect of being extremely inexpensive to manufacture.

[Brief explanation of drawings]

FIGS. 1A to 1E are process explanatory diagrams showing one embodiment of the method for manufacturing a laminated piezoelectric element according to the present invention, and FIGS. 2 and 3 are explanatory diagrams of the prior art, respectively. 30... Sintered piezoelectric ceramic plate, 32...
Internal electrode, 34... Piezoelectric laminate, 36... Glass plate, 38... Notch, 40... External electrode.

Claims (1)

[Claims] 1 A large number of piezoelectric ceramic plates each having a conductive layer formed on the surface thereof to serve as an internal electrode are laminated and bonded together with an adhesive, and the side surfaces of the obtained piezoelectric laminate are covered with an insulating material, and the first side surface is insulated. The portions corresponding to the internal electrodes of the object are removed every other layer to expose the end faces of the internal electrodes, and the portions corresponding to the internal electrodes of the insulator on the second side are shifted one layer from the first side and removed every other layer. A method for manufacturing a laminated piezoelectric element, characterized in that the end surfaces of the internal electrodes are exposed, external electrodes are provided on each of the first and second side surfaces, and the internal electrodes are connected on each side surface.