JPS62199076A - Manufacture of laminated type piezoelectric element - Google Patents

Abstract

PURPOSE:To simplify manufacturing processes and to improve the reliability of mechanical strength, by providing piezoelectric ceramic plates, in which inner electrodes are formed with non-electrode parts being made to remain, laminating and bonding many piezoelectric ceramic plates, cutting the ceramic plates so as to cut said non-electrode parts, providing outer electrodes at the cut-out recess parts of the non-electrode parts, and connecting the inner electrodes. CONSTITUTION:Inner electrodes 32 are formed in each piezoelectric ceramic plate 34 so that many non-electrode parts 30 remain at a specified pitch. The non-electrode parts are provided at positions, which are shifted on both upper and back surfaces. Many piezoelectric ceramic plate 34 are laminated and bonded. This laminated block is cut along broken lines so as to cut each non- electrode part 30 at two places. Thus piezoelectric laminated bodies 36 are prepared. A recess part 38 is formed by providing a notch in each non-electrode part. The end of an inner electrode is exposed to each recess part 38. As an outer electrode 40, a conductive bonding agent is applied on the recess parts 38. The inner electrodes 32 are connected with each other, and the laminated type piezoelectric element is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a laminated piezoelectric element used in a piezoelectric actuator, etc. A large number of sintered piezoelectric ceramic plates having internal electrodes of the same shape are laminated and integrated by adhesion, and then cut so that the electrodeless part spans two or more places, and then the electrodeless part is made slightly smaller than its size. The present invention relates to a method of manufacturing a laminated piezoelectric element in which cutout internal electrodes are alternately exposed and external electrodes are applied.

[Prior Art] Piezoelectric actuators and 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 is used, for example, as shown in FIG.
A metal terminal plate 12 (approximately 35 to 35 mm thick) is formed by baking an electrode layer of silver or the like on both sides of the sintered piezoelectric ceramic temporary IO (approximately I11), and etching it to approximately the same dimensions as the electrode layer.
50 μm) and apply adhesive to each sheet to attach the metal terminal 12.
This is a method of laminating and bonding several tens to hundreds of layers with the directions a aligned, and then connecting each two corresponding sets of metal terminals 12a with lead wires 14 for assembly.

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, laminated and crimped, integrally sintered, and external electrodes are formed after cutting to a predetermined size. As shown in FIG. 5, an internal electrode 16 such as platinum is interposed between the piezoelectric ceramic plates 10, and an insulating material 18 such as glass is disposed on the side surface of each internal electric bridge every other layer.
The structure is such that the external electrode 20 is coated and covered, and then the external electrode 20 is coated on top of that.

[Problems to be Solved by the Invention] However, the former method using lamination adhesion requires extremely complicated work because it requires piezoelectric ceramic plates of a predetermined shape and metal terminal plates to be laminated with their terminal directions aligned. The drawback is that it is difficult to mass produce and is difficult to reduce in price.

On the other hand, the latter integral sintering method has the advantage of being able to cut out a large number of piezoelectric laminates by laminating them once, thereby saving the labor of laminating work.

However, the sintering temperature of piezoelectric ceramic is 1200-1300
℃, and the ceramic composition is lead compound, which is highly reactive, and the internal electrodes are limited to expensive noble metals such as platinum, which means that the cost of electrode materials is high. In addition, the platinum internal electrode must be formed on the entire surface of the interlayer to avoid unrestrained strain, which has a structural defect that limits the ceramic solid phase reaction between the eyebrows and reduces the adhesion strength.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, to enable the use of inexpensive materials for internal electrodes, to cut out a large number of piezoelectric laminates by laminating them once, and to form external electrodes as well. It is an object of the present invention to provide a method for manufacturing a laminated piezoelectric element, which greatly simplifies the manufacturing process, 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 This is a method of manufacturing an AL-type piezoelectric element that has been improved to be suitable for mass production by devising the connection structure between i8i and external electrodes.

That is, the present invention uses a sintered piezoelectric ceramic plate on which internal electrodes are formed so as to leave a large number of non-electrode portions (portions where 111 poles are not applied) which are shifted from each other at a predetermined pitch on both the front and back surfaces. .

Then, a large number of piezoelectric ceramic plates are stacked so that the positions of their non-electrode portions match and face each other, and are bonded together with an adhesive to obtain a laminate block.

Next, the obtained laminate block is cut so that the non-electrode portions extend over at least two locations to produce a piezoelectric laminate. At the position of the non-electrode portion of this piezoelectric laminate, a notch recess is formed in the stacking direction, slightly smaller in size than the non-electrode portion.

An external electrode is provided in this recess to connect the exposed internal electrodes. 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, it is possible to use inexpensive materials such as silver and nickel while leaving the interior intact. Furthermore, since the internal electrode lead-out structure has been devised, there is no need to insert metal terminal plates, and a large number of piezoelectric laminates can be obtained by cutting out a block of predetermined dimensions from a block obtained by a single lamination operation.

To connect the internal electrodes and external electrodes, instead of attaching insulators to predetermined positions on the piezoelectric laminate, the internal electrodes are exposed every other layer by simply cutting out the sides of the piezoelectric laminate at predetermined positions. Since it is only necessary to attach external electrodes, the work is easy even if the thickness of the piezoelectric ceramic plate is extremely thin or even if the number of laminated sheets is extremely large.

[Example] FIG. 1 is a process explanatory diagram showing an example of the method of the present invention. First, as shown in the figure, a large number of sintered piezoelectric ceramic plates 34 on which internal electrodes 32 of a predetermined shape with a large number of non-electrode parts 30 are formed on the front and back surfaces are laminated and bonded together using an adhesive. Unify. As the piezoelectric ceramic plate 34, for example, one having dimensions of about 50a+s+ in length and width and about 0.2 ms in thickness is suitable.

The details of each piezoelectric ceramic plate 34 are shown in FIGS. 2 and 3. Internal electrodes 32 are formed on the piezoelectric ceramic temporary 34 so that a large number of non-electrode portions 30 of about 2.5+m+aφ remain at a predetermined pitch vertically and horizontally. Ru. The non-electrode portions 30 are provided at positions shifted from each other on both the front and back surfaces.

For example, if we look at the position of one non-electrode portion (indicated by 212+) of a certain piezoelectric ceramic plate 34a, the internal electrode 32 is formed so that the non-electrode portion 30a remains on the upper surface, and the internal electrode 32 is formed on the entire surface so that the non-electrode portion 30a remains on the lower surface. Internal electrode 32
is formed. Looking at the corresponding positions of the piezoelectric ceramic plate 34b immediately below it, internal electrodes 32 are formed on the entire upper surface thereof, and internal electrodes 32 are formed on the lower surface so that an electrodeless portion 30b remains. At the position Zz Zz, which is shifted by 1/2 pitch, the electrode pattern is exactly reversed.

The internal electrodes 32 can be easily formed, for example, by screen printing and baking silver paste. 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 since mass production technology has already been established, it is inexpensive and easy. It is possible to manufacture

For example, epoxy adhesive is screen printed on such piezoelectric ceramic plates 34, tens to hundreds of sheets are laminated, and the piezoelectric ceramic plates 34 are tightened and hardened in a vise. In order to simplify the drawing, only a relatively small number of piezoelectric ceramic plates are shown in FIG. 1, but in reality, a large number of piezoelectric ceramic plates are laminated as described above. This lamination bonding is carried out in such a way that the positions of the non-electrode parts are opposite and face each other. The height of the stacked blocks will be a constant value depending on the printing thickness of the adhesive, the pressure between the blocks, etc.

Next, this laminated block is cut out using a cutting machine using a diamond blade or the like at the positions indicated by the broken lines in FIG. , a piezoelectric laminate 36 as shown in FIG. 3B is manufactured.

The obtained piezoelectric laminate 36 has electrodeless portions at two locations on both sides. At the center of this electrode-free part, a cutout is made in the stacking direction slightly smaller than the size of the non-electrode part (see C in the same figure). For example 2.
Cut the 5 mmφ non-electrode portion with a diamond blade shaped to 0.7 mmH. In the recess 38 thus formed, the end portion of the internal electrode formed entirely (without leaving any non-electrode portion) is exposed, but the end portion of the internal electrode with the non-electrode portion remaining is not exposed. Therefore, the stacked internal electrodes are exposed alternately at the two recesses 38.

Finally, as shown in the figure, such a piezoelectric laminate 36
A conductive adhesive is applied as an external electrode 40 to both recesses 38 to obtain a laminated piezoelectric element.

The polarization of each piezoelectric ceramic plate 34 is basically performed when the plate is alone, but in some cases it may be performed after lamination and bonding.

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, they can also be formed with nickel plating or the like.

The shape and dimensions of the non-electrode portion formed on the piezoelectric ceramic plate,
The arrangement etc. can be changed as appropriate. The cutting position of the laminated block can also be changed depending on the pattern of the internal electrodes formed. It is not necessary to cut out the cross shape at the position of the electrodeless part, that is, the structure can be such that the electrodeless part is not located at the corner of the piezoelectric carcass but appears at the center of the side surface.

[Effects of the Invention] As described above, the present invention comprises laminating and bonding sintered piezoelectric ceramic plates each having an internal electrode of a predetermined shape in which a large number of non-electrode portions are arranged so that the non-electrode portions span two or more locations. After shredding, slight notches are made in the stacking direction at the positions of the non-electrode parts to expose internal electrodes alternately and apply external electrodes, so there is no need to insert metal terminal plates, etc.
This method has the advantage that a large number of piezoelectric laminates can be obtained at the same time by a simple method of lamination bonding and cutting using large piezoelectric ceramic plates.

Furthermore, since the present invention uses an adhesive-based integration method, the use of a strong structural adhesive increases mechanical strength and improves reliability.Furthermore, it is possible to use inexpensive electrode materials for the internal electrodes. Coupled with the fact that it can be cut out, it has the effect of being able to be manufactured at a low cost.

Furthermore, the interconnection of each internal electrode is extremely easy, as it can be completed by simply machining grooves and attaching conductive material to the recesses formed thereby, and has excellent effects such as being able to cope with even thinner piezoelectric ceramic plates. There is.

[Brief explanation of drawings]

1A to 1D are process explanatory diagrams showing one embodiment of the method for manufacturing a laminated piezoelectric element according to the present invention, FIG. 2 is an explanatory diagram showing the structure of a piezoelectric ceramic plate, and FIG. The sectional view, FIG. 4, and FIG. 5 are explanatory diagrams of the prior art, respectively. 30... Non-electrode portion, 32... Internal electrode, 34...
・Sintered piezoelectric ceramic plate, 36... piezoelectric laminate,
38... Concave portion, 40... External electrode. Patent applicant: Fuji Electrochemical Co., Ltd. Agent: Minoru Shigeru B
CD 5t j4 3'+ 55
3 623440Figure 3Figure 4Figure 5

Claims (1)

[Claims] 1. A large number of piezoelectric ceramic plates on which internal electrodes are formed so as to leave a large number of non-electrode parts that are offset from each other on the front and back sides at a predetermined pitch are stacked together with adhesive so that the positions of the non-electrode parts match and face each other. A piezoelectric laminate is produced by bonding and integrating, and then cutting so that the non-electrode portion covers at least two or more locations.The non-electrode portion is cut out slightly smaller than its size, and the external A method for manufacturing a multilayer piezoelectric element, characterized by providing electrodes and connecting exposed internal electrodes.