JPH03155176A - Manufacture of laminated piezoelectric element - Google Patents

Abstract

PURPOSE:To enable an end face of an internal electrode which is exposed at every other layer to be insulated onto the side surface of a piezoelectric body easily and without any need for accuracy, improve productivity, and reduce cost by laminating a piezoelectric material and an electrode plate alternately so that a protrusion of the electrode plate may be in opposite direction at every other layer, by covering the entire piezoelectric laminated layer with a thin-film sheet, and by heating this sheet closer to a softening point for adhesion onto the side surface of the laminated body. CONSTITUTION:A plurality of piezoelectric plates 1 consisting of a piezoelectric material and a plurality of metal electrodes 2 which are in the same shape and are equipped with a protrusion 2a for external lead-out are laminated to enable a laminated body 4 to be produced so that the protrusion 2a may protrude to the opposite side at every other layer. The outside of a protrusion which protrudes to both sides of this laminated body is covered with a thin-film sheet 5 made of an insulation material, thus covering the entire side surface of the laminated body. Then, the sheet 5 is heated closer to a softening point, thus enabling the sheet to be adhered to the side surface of the laminated body. Then, each conductive external electrode 7 is bridged to the outside of the protrusion 2a which is located at the same side of the laminated body 4 and each protrusion is sandwiched from the outside by this external electrode 7, thus enabling the external electrode to be joined to each protrusion electrically.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a laminated piezoelectric element, and in particular, it is possible to easily remove parts other than the protrusions of a metal electrode in which protrusions protrude on the same side in every other layer. The present invention relates to a method of manufacturing a laminated piezoelectric element that can be insulated.

[Conventional technology]

Piezoelectric elements with a multilayer capacitor structure are excellent actuators that generate large distortions at low voltages. For this reason,
Manufacturing equipment for various electronic components such as semiconductors that perform microfabrication,
This piezoelectric actuator is used in optical devices and the like that require minute positioning. In addition, a stacked piezoelectric actuator has been put into practical use, in which such piezoelectric elements and electrode plates are alternately stacked, and the electrodes located above and below each layer are connected to different voltage sources to increase the amount of strain generated. In recent years, laminated piezoelectric actuators have also come to be used as control parts for dot printer heads and the like.

By the way, in order to connect the electrodes of every other layer to the same power source as described above, the laminated piezoelectric actuator is connected to another power source located between two electrode plates (or electrode layers) connected to the same power source. It is necessary to insulate the ends of the electrode plates (or electrode layers) to prevent short circuits.

FIG. 11 shows a conventional insulation method disclosed in Japanese Utility Model Application Publication No. 64-39665. In the figure, 11 is a ceramic layer and 12 is an internal conductor layer, which are alternately laminated. No metal electrode plate is used in the laminated piezoelectric body of this example. The internal conductive layers 12 exposed on the two opposing sides are insulated by glass insulating layers 16 every other layer, and the external electrodes 17 are coated on both sides so that they do not come into contact with the insulated internal conductive layers 12. installed. Reference numeral 19 indicates a lead wire for connecting this external electrode 17 to a power source, and 18 indicates its solder portion. In addition, the side edges of the internal conductor layers (internal electrodes) are insulated in the same manner as this with synthetic resin every other layer, and then the external conductor layers (
JP-A-59-128 discloses a device with external electrodes formed thereon.
There is a disclosure in Japanese Patent Laid-Open No. 683, and an example is further disclosed in JP-A No. 61-23, in which the sides of the piezoelectric element are raised with glass frit and the exposed parts of the internal electrodes located in the grooves are filled every other layer with an insulating material.
This is shown in Japanese Patent No. 4579.

On the other hand, as an alternative method, a metal plate with a smaller pressure-receiving area than the piezoelectric element is sandwiched between the piezoelectric elements, and insulation is achieved by preventing the metal plate from being exposed on the side of the piezoelectric element except for the protrusion for external extraction. There are also some (for example, 1986)
-42791)).

[Problem to be solved by the invention]

However, the conventional method of sealing the exposed parts of the internal electrodes on the side surfaces of a multilayer piezoelectric element with an insulating material such as glass every other layer does not work, even if the internal electrodes are of the printed type as described above.
Even if it is a type in which metal plates are sandwiched, a complicated and highly accurate insulation process is required, which results in poor productivity and increased costs. Furthermore, the method of sandwiching a metal plate with a smaller pressure-receiving area than the piezoelectric element between the piezoelectric elements has the problem that stress is concentrated on the piezoelectric element near the outer periphery of the metal plate, causing fine cracks in the piezoelectric element.

The present invention solves the problem of the complicated and high-precision insulation process in the conventional laminated piezoelectric element, uses a metal plate with the same shape as the piezoelectric element as the internal electrode, and connects the external electrode to this metal plate. In a laminated piezoelectric body of the type that uses the protrusions provided, the end faces of internal electrodes exposed every other layer on the sides of the piezoelectric body can be insulated easily and without requiring precision, increasing productivity. It is an object of the present invention to provide a method for manufacturing a laminated piezoelectric element that can improve the manufacturing process and reduce costs.

[Means to solve the problem]

A method for manufacturing a laminated piezoelectric element of the present invention that achieves the above object includes a piezoelectric plate made of a piezoelectric material and a metal electrode having the same shape as the piezoelectric plate and having protrusions for external extraction, such that the protrusions are opposite to each other every other layer. a step of laminating a plurality of sheets so as to protrude to the side to form a laminate; and a step of wrapping the outside of the projections protruding on both sides of the laminate with a thin film sheet made of an insulating material to cover the entire side surface of the laminate. , heating the sheet to near its softening point to adhere the sheet to the side surface of the laminate;
a step of extending a conductive external electrode to the outside of each of the protrusions on the same side of the laminate, and sandwiching each protrusion from the outside with the external electrode to electrically connect the external electrode and each protrusion; It is characterized by becoming.

[Effect]

In the method for manufacturing a laminated piezoelectric element of the present invention, first, a piezoelectric laminate is produced by alternately laminating piezoelectric materials and electrode plates such that the protrusions of the electrode plates are oriented in opposite directions on every other layer. The entire piezoelectric laminate is then covered with a thin sheet of insulating material, which is heated to near its softening point and adheres to the side surfaces of the laminate. At this time, a thin film sheet with a very small thickness is attached to the protrusion of the electrode plate, or the protrusion is exposed by breaking through the thin film sheet. Thereafter, the protrusions on the same side are sandwiched between conductive external electrodes and electrically connected.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for manufacturing a laminated piezoelectric element of the present invention will be described in detail below with reference to the accompanying drawings.

When manufacturing piezoelectric laminates, lead zirconate titanate P
b(TixZr+-++)Oz (X = 0.4~
First, a slurry is prepared by adding a small amount of an organic binder to a piezoelectric material calcined powder whose main component is 0.6 (molar ratio is 0.6) and dispersing this in an organic solvent. This slurry is then applied onto a Mylar film to a thickness of 600 microns using a casting film forming apparatus used in the manufacture of ordinary multilayer ceramic capacitors and dried. Subsequently, this is peeled off from the film to produce a piezoelectric material green sheet.

This green sheet is cut into a predetermined size, for example, 30 mm in diameter.
A piezoelectric plate 1 of uniform dimensions as shown in FIG. 1 is made by cutting into a circular shape of mm. Furthermore, an internal electrode 2 having the same shape as this piezoelectric plate 1 is provided.
is formed using a metal plate. This internal electrode 2 is provided with a protrusion 2a for external extraction. Then, these piezoelectric plates 1 and internal electrodes 2 are alternately arranged in a predetermined number, for example, 4 so that the protrusions 2a of the internal electrodes 2 alternately protrude to the opposite side.
0 sheets are laminated, and shims 3 made of piezoelectric material are laminated on the top and bottom. The laminated piezoelectric plates 1 and internal electrodes 2 are integrated by heat pressing, and then the binder is scattered at 500°C to obtain a distance of 500 between the internal electrodes as shown in Fig. 2.
A micron piezoelectric laminate 4 is made.

Next, the piezoelectric laminate 4 is placed horizontally, and the protrusion 2 of the internal electrode 2 is
Turn one side of a upward. In this state, a thin film sheet 5 made of an insulating material, for example a synthetic resin, is approached from above. As shown in FIG. 3, the thin film sheet 5 is lightly restrained by the gripping member 6 until the thin film sheet 5 touches the protrusion 2a of the piezoelectric laminate 4. Thereafter, the thin film sheet 5 is released from the gripping member 6, and the piezoelectric laminate 4 is covered with the thin film sheet 5 without applying excessive force to the projections 2a of the internal electrodes 2.

The final end of the thin film sheet 5 is temporarily fixed to the side surface of the piezoelectric laminate 4 with an adhesive.

After this, the piezoelectric laminate 4 is turned over and the protrusion 2 on the opposite side is
Turn a upward. Then, in this state, the same thin film sheet 5 is approached from above. As shown in FIG. 4, the thin film sheet 5 is lightly restrained by the gripping member 6 until the thin film sheet 5 touches the protrusion 2a of the piezoelectric laminate 4.

Thereafter, the thin film sheet 5 is released from the gripping member 6, and the thin film sheet 5 is
is placed on the piezoelectric laminate 4. At the final end of the thin film sheet 5, the thin film sheet 5 is temporarily attached to the side surface of the piezoelectric laminate 4.
The overlapping parts are bonded using high-frequency seam welding, etc.

FIG. 5 shows a cross section of the piezoelectric laminate 4 produced by the process described above. It should be noted that the number of stacked piezoelectric plates 1 in FIG. 5 is much smaller than the actual number of stacked plates for illustrative purposes. The thin film sheet 5 is stretched over the side surface of the piezoelectric laminate 4 like a tent by the protrusions 2a of the internal electrodes 2.

In this state, the thin film sheet 5 is heated to near its softening point so that the force applied to the thin film sheet 5 is almost zero. This heating temperature is generally about 100-odd degrees Celsius. Note that at this time, the piezoelectric laminate 4 side may be heated. Furthermore, if the metal parts, that is, the internal electrodes 2 and the protrusions 2a, are heated intensively by high-frequency heating, the effect will be noticeable.

The thin film sheet 5 softened by heating gradually adheres to the surface of the piezoelectric laminate 4. At this time, the protrusion 2a of the internal electrode 2
The thin film sheet 5, which was held by the The projections 2a are exposed to the outside of the thin film sheet 5.

After this, thin plate-shaped external electrodes 7 made of stainless steel material are placed on the outside of the protrusions 2a, and both sides of the protrusions 2a of the external electrodes 7 are pressed with strong force, and the external electrodes 7 are used to protrude the protrusions. 2a are sandwiched as shown in FIG. At this time, the thin film sheet 5 covering the protrusion 2a is pushed away by the external electrode 7, so the external electrode 7 and the protrusion 2a come into contact with each other.
When sandwiching the protrusion 2a between the external electrodes 7, if the thin film sheet 5 near the sandwiched protrusion 2a is melted while heating with high frequency, the bonding between the protrusion 2a and the external electrode 7 will be more reliable. . Furthermore, if the external electrode 7 is made of a strong material and provided with a sharp protrusion 7a as shown in FIG. The bonding becomes reliable. Then, the sandwiched external electrode 7 is spot-welded by resistance heating to electrically connect the external electrode 7 and the protrusion 2a.

FIG. 10 shows the overall structure of a piezoelectric laminate 4 manufactured by the method for manufacturing a laminated piezoelectric element as described above.

The external electrode 7, which connects the protrusion 2a of the internal electrode 2, is then connected to a different power source via a lead wire 8. As can be seen from this figure, since almost the entire outer surface of the piezoelectric laminate 4 is covered with the two thin film sheets 5, the vicinity of the base of the protrusion 2a of the internal electrode 2 is reliably insulated. Therefore, the two external electrodes 7 do not come into contact with the ends of the internal electrodes 2 having opposite polarities, and there is no risk of short circuit.

[Effects of the Invention] As explained above, according to the method of manufacturing a laminated piezoelectric element of the present invention, a metal plate having the same shape as the piezoelectric element is used as the internal electrode, and the connection with the external electrode is made by using this metal plate. In a laminated piezoelectric body of the type that uses the protrusions provided, the end faces of internal electrodes exposed every other layer on the sides of the piezoelectric body can be insulated easily and without requiring precision, increasing productivity. This has the effect of improving performance and reducing costs.

[Brief explanation of the drawing]

1 to 9 are diagrams showing the steps of the method for manufacturing a laminated piezoelectric element of the present invention. FIG. 1 is a manufacturing process diagram of a piezoelectric laminate, and FIGS. Figure 5 is a cross-sectional view of the piezoelectric laminate covered with the thin film sheet, and Figures 6, 7, and 7 are the parts showing the state of the thin film sheet when heated from the state shown in Figure 5. Cross-sectional view, Figures 8 and 9
10 is a side view showing the overall structure of a laminated piezoelectric element manufactured by the manufacturing method of the present invention,
FIG. 11 is a perspective view showing a conventional method of insulating internal electrodes. DESCRIPTION OF SYMBOLS 1... Piezoelectric plate, 2... Internal electrode, 2a... Protrusion,
3...Shim, 4...Piezoelectric laminate, 5...Thin film sheet, 7...External electrode, 8...Lead wire.

Claims (1)

[Claims] A plurality of piezoelectric plates made of a piezoelectric material and metal electrodes having the same shape and having protrusions for external extraction are stacked so that the protrusions protrude every other layer to the opposite side. forming a laminate; wrapping the outside of the projections protruding on both sides of the laminate with a thin film sheet made of an insulating material to cover the entire side surface of the laminate; heating the sheet to near its softening point; The step of attaching the sheet to the side surface of the laminate, and extending conductive external electrodes to the outside of the protrusions on the same side of the laminate, sandwiching each protrusion from the outside with the external electrodes to connect the protrusions to the outside. 1. A method for manufacturing a laminated piezoelectric element, comprising the steps of electrically bonding an electrode and each protrusion; and manufacturing a laminated piezoelectric element.