JPH0324074B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing a laminated piezoelectric element used in a piezoelectric actuator, etc., and more specifically, to a method for manufacturing a laminated piezoelectric element used in a piezoelectric actuator, etc. A large number of sintered piezoelectric ceramic plates are bonded together, the holes are cut into pieces at two or more places, and the internal electrodes are exposed in the recesses. The present invention relates to a method of manufacturing a laminated piezoelectric element that is electrically connected.

[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.

Methods for manufacturing laminated piezoelectric elements used in such piezoelectric actuators include a method of bonding together a large number of sintered piezoelectric ceramic plates;
There is a method of laminating unsintered sheets and then sintering them together.

The former lamination adhesion method, for example, as shown in Fig.
A metal terminal plate 1 is made by forming an electrode layer using baked silver or the like on both the front and back sides of a sintered piezoelectric ceramic plate 10 (approximately 1 mm) in size, and etching it to approximately the same size.
2 (approximately 35 to 50 μm thick) are applied with adhesive one by one, the directions of the metal terminals 12a are aligned, and tens to hundreds of layers are bonded together, and then two corresponding sets of metal terminals 12a are bonded.
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. 5, 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 internal electrode layer, and then The configuration is such that the external electrode 20 is applied from scratch.

[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. The drawback is that it is difficult to mass produce and is difficult to reduce 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 1200 to 1300°C, and the composition of ceramics is a lead compound that is highly reactive, so internal electrodes are limited to expensive noble 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 This is a manufacturing method for a laminated piezoelectric element that has been improved to be suitable for mass production by devising a connection structure between electrodes and external electrodes.

That is, the present invention provides a sintered piezoelectric ceramic having a structure in which a large number of holes are bored at a predetermined pitch, and an internal electrode is formed on one side of each hole to reach the edge of the hole and leave the edge of the hole on the other side. A board is used. A large number of piezoelectric ceramic plates are then laminated so that the hole positions match and the same electrode shapes face each other, and the plates are bonded together with an adhesive to obtain a laminate block.

Next, the obtained laminate block is cut so that the holes are divided into at least two places to produce a piezoelectric laminate. Therefore, in this piezoelectric laminate, two or more recesses formed by dividing holes appear in the stacking direction.

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, 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.

The connection between internal electrodes and external electrodes is also achieved by using external electrodes to connect internal electrodes exposed every other layer to recesses formed on the sides of the piezoelectric laminate, rather than attaching insulators to predetermined positions on the piezoelectric laminate. Since it is only necessary to connect the piezoelectric ceramic plates, the work is easy even if the thickness of the piezoelectric ceramic plate is extremely thin or even if the number of laminated plates 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 Figure A, a large number of holes 3
A large number of sintered piezoelectric ceramic plates 34 having internal electrodes 32 of a predetermined shape formed on their surfaces are laminated and bonded together using an adhesive. For example, the piezoelectric ceramic plate 34 has a thickness of 50 mm in length and width.
A size of about 0.2 mm is suitable.

Details of each piezoelectric ceramic plate 34 are shown in FIGS. 2 and 3. The piezoelectric ceramic plate 34 has a diameter of 2 mm.
A large number of holes 30 of the same size are drilled at a predetermined pitch in the vertical and horizontal directions. Then, the internal electrode 32 is formed so as to reach the edge of the hole on one side but leave the edge of the hole on the other side.

For example, regarding one hole 30a in a certain piezoelectric ceramic plate 34a, an internal electrode 32 is formed on the upper surface of the hole 30a until it reaches the edge of the hole, and an internal electrode 32 is formed on the lower surface of the hole 30a so as to leave the edge of the hole. Looking at the corresponding hole 30b of the anti-electroceramic plate 34b immediately below, an internal electrode 32 is formed on the upper surface so as to leave the edge of the hole, and an internal electrode 32 is formed on the lower surface up to the edge of the hole. Each piezoelectric ceramic plate has internal electrode patterns arranged alternately in a grid pattern for each hole, leaving a hole edge.

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

Note that the holes 30 may be formed in the piezoelectric ceramic plate 34 before sintering or after sintering. When the holes are formed after sintering, they may be formed before or after the internal electrodes are formed.

For example, epoxy adhesive is screen printed on such piezoelectric ceramic plates 34, several tens to hundreds of sheets are laminated, and the piezoelectric ceramic plates 34 are tightened and cured 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 will be laminated as described above. This lamination bonding is performed using a guide pin so that the hole positions match and the electrodes of the same shape face each other. The height of the stacked blocks becomes a constant value depending on the printing thickness of the adhesive, the sandwiching pressure, etc.

Next, this laminated block is cut into a shape using a cutting machine using a diamond blade or the like at the position shown by the broken line in FIG. Then, a piezoelectric laminate 36 as shown in FIG. 1B is manufactured.

The resulting piezoelectric laminate 36 has recesses 38 formed by dividing the holes at two locations on both sides. In this recess 38, the internal electrode portion that is formed to reach the hole edge is exposed, but the internal electrode portion that remains at the hole edge is not exposed. Therefore, each stacked internal electrode has 2
The recesses 38 are exposed alternately.

Finally, as shown in Figure C, a conductive adhesive is applied as external electrodes 40 to both recesses 38 of the piezoelectric laminate 36 to obtain a laminate piezoelectric element.

The polarization of each piezoelectric ceramic plate 34 is basically carried out when the plate is alone, but in some cases it may be carried out after the piezoelectric ceramic plates 34 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, they can also be formed with nickel plating or the like. The shape of the holes formed in the piezoelectric ceramic plate and the internal electrode pattern can be changed as appropriate. In the above embodiment, an internal electrode pattern is provided in which hole edges are left in a lattice pattern, but a pattern in which hole edges are left in every other row may be repeated. Furthermore, the cutting position of the laminated block can be changed depending on the pattern of the internal electrodes formed. It is not necessary to cut out a cross at the hole location. In other words, it is also possible to have a structure in which the recesses are not located at the corners of the piezoelectric laminate but appear at the center of the side surface.

[Effects of the Invention] As described above, the present invention involves laminating and bonding sintered piezoelectric ceramic plates in which a large number of holes are arranged to form internal electrodes of a predetermined shape, and then cutting the holes into pieces so as to divide the holes into two or more places. Since the internal electrode is exposed in the recessed part and the external electrode is applied for connection, there is no need to sandwich a metal terminal plate, etc., and a simple method of laminating and cutting using a large piezoelectric ceramic plate can be used. This has the advantage that a large number of piezoelectric laminates can be obtained at once. The holes formed in the piezoelectric ceramic plate can also be used for positioning during the formation of internal electrodes and lamination bonding, improving workability and manufacturing accuracy.

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, inexpensive electrode materials can be used for the internal electrodes, so many of the above-mentioned Combined with the fact that it can be cut into pieces, it has the effect of being extremely inexpensive to manufacture.

Furthermore, the interconnection of each internal electrode is extremely easy as it can be completed by simply attaching conductive material to the recess, and the external electrodes can be attached sufficiently thickly without protruding, allowing for connection without causing any problems when incorporating into equipment. It has excellent effects such as improving the reliability of the piezoelectric ceramic plate and being able to cope with even thinner piezoelectric ceramic plates.

[Brief explanation of drawings]

1A to 1C 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. 3 is a cross-sectional view thereof. , FIG. 4, and FIG. 5 are explanatory diagrams of the prior art, respectively. 30... Hole, 32... Internal electrode, 34... Sintered piezoelectric ceramic plate, 36... Piezoelectric laminate, 3
8... recess, 40... external electrode.

Claims (1)

[Claims] 1. A piezoelectric ceramic plate with a large number of holes drilled at a predetermined pitch and internal electrodes formed on each hole so that one side reaches the hole edge and the other side leaves the hole edge is used. In addition, a large number of piezoelectric laminates are produced by laminating a large number of piezoelectric laminates so that the same electrode patterns face each other and bonding them together with an adhesive, and then cutting the holes so as to divide them into at least two or more places, so that the holes are divided. 1. A method for manufacturing a multilayer piezoelectric element, comprising: providing an external electrode in a recess formed in the process, and connecting exposed internal electrodes.