JPH01184968A - Manufacture of laminar piezoelectric element - Google Patents

Abstract

PURPOSE:To improve in productivity by a method wherein a laminate is built of piezoelectric material sheets and inner electrodes stacked up one upon another alternately, the laminate is subjected to sintering, the edge of every other inner electrode in one side of the laminate is subjected to electrolytic etching for the creation of a groove, and the groove is filled with an insulating material which serves as an insulating layer. CONSTITUTION:A green sheet is built of a calcinated piezoelectric material powder composed mainly of lead nickel-niobate and lead titanate, and an AgPd paste to be an inner electrode 2 is applied thereto by screen-printing. About fifty of such are stacked up and bonded into a laminate under a hot press. The laminate is so cut in the direction vertical to the sheets that all the ends of the inner electrodes 2 will be exposed in the sides of the laminate. The product is then subjected to sintering. A process follows wherein provisional outer electrodes 8, 8' are built for the construction of a laminar piezoelectric body 9 of a laminar capacitor type. An electrolytic etching process follows, wherein the end of every other layer attacked in the process is replaced with a groove, in a side wherein inner electrode 2 are exposed. Grooves are formed, similarly, in the other sides. An insulating paste is allowed to flow into the thusformed grooves. The laminar piezoelectric body 9 produced in this way is cut at the provisional outer electrodes 8, 8', which results in a laminar piezoelectric body 9' lacking outer electrodes. A conductive material is applied to insulating layers 3 in the laminar piezoelectric body 9' for the formation of outer electrodes 4.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing a laminated piezoelectric element.

(Prior art and its problems) A laminated piezoelectric body that utilizes displacement due to the piezoelectric inverse effect is produced by providing an electrode on a piezoelectric ceramic thin plate and laminating a large number of them by bonding, as shown in Japanese Patent Laid-Open No. 49-86816. It has a similar structure. As shown in Fig. 7, the two external electrodes (lead wires 6) arranged on the sides of the internal electrode 2 provided with the ceramic thin plate (piezoelectric material 1) It is connected. However, in the laminated piezoelectric body described above, the thickness of the ceramic thin plate is 0.
If the thickness is less than 15 mm, it will be industrially difficult to connect every other layer of internal electrodes 2, so the thickness of the ceramic thin plate should be 0.
, 5- or more. Therefore, the voltage required to drive the laminated body is several hundreds of volts or more, which is inconvenient.

Therefore, in recent years, with the aim of obtaining a multilayer piezoelectric displacement element that is compact and can be driven at low voltage by integral firing, a thickness of 0.03 to 0.5
An attempt was made to apply the technology of laminated capacitors, which is obtained by printing electrode paste on one side of a ceramic green sheet, laminating a large number of sheets using thermocompression bonding, and then firing them to form external electrodes.

It became possible to lower the driving voltage. However, in a multilayer capacitor type multilayer piezoelectric displacement element, as shown in Fig. 8, the area of each internal electrode 2 is smaller than the area of the piezoelectric material 10, so the distribution of internal strain generated by the application of an electric field becomes uneven, making it easy to break. There is a drawback.

To solve this problem, as shown in FIG. 9, if the area of each internal electrode 2 and the area of the layer of piezoelectric material 1 are made equal, the strain distribution inside the piezoelectric material becomes uniform.

Therefore, even when an electric field is repeatedly applied, no damage occurs. However, in this case, in order to connect the internal electrodes in parallel, the ends of each internal electrode must be connected every other layer. For example, as shown in FIG. 9, a method of printing a metal m right every other layer on the end of the internal electrode 2 and connecting them by wire bonding 6' (1960-72 As shown in Japanese Patent Laid-Open No. 58-196068, an insulating paste is printed and baked on every other layer of the inner electrode end to form an insulating layer, and then a conductive material layer (external electrode) is formed on top of the insulating paste. A method has been proposed.

However, in these methods, when changing the thickness of the piezoelectric material, it is necessary to change the printing screen for forming the electrode film and the insulating layer.

In addition, particularly when the interval between the internal electrodes is 0.3 cylinders or less, there is a problem in that printing positions tend to shift easily and the reliability of the parallel connection of the internal electrodes is insufficient.

In view of the above-mentioned problems, the present invention provides that the area of the internal electrode and the area of the piezoelectric material layer are substantially equal, there is no risk of destruction even when an electric field is repeatedly applied, and the space between the internal electrodes is small. The present invention also provides a method for efficiently connecting the ends of internal electrodes in parallel and manufacturing a multilayer piezoelectric element with high productivity.

(Means for Solving the Problems) The present invention integrates a plurality of piezoelectric materials and internal electrodes by alternately stacking and sintering them, and then forming temporary external electrodes on each of two opposing sides. , a step of insulating the laminated layers, a step of cutting the insulated laminated piezoelectric body near the temporary external electrode, and an external electrode connected to the internal electrode on the two insulated surfaces of the cut laminated piezoelectric body. In a method of manufacturing a laminated piezoelectric element, the area of the internal electrode surface and the area of the piezoelectric material surface are substantially equal.

One side of the exposed internal electrode of the laminated piezoelectric body is immersed in an electrolytic etching solution, and a voltage is applied to one temporary external electrode to perform electric field etching on the end of the internal electrode connected to the temporary external electrode. The end portions of the internal electrodes on one side surface are made into recesses every other layer. 9 Then, the end portions of the internal electrodes on the other side surface which are connected to the opposing temporary external electrodes are made into recesses every other layer.

The present invention relates to a method of manufacturing a laminated piezoelectric element in which the ends of internal electrodes are insulated by filling these recesses with an electrically insulating member and forming an insulating layer.

In the present invention, the piezoelectric material is not limited as long as it has an excellent electrostrictive effect, such as lead nickel niobate, lead titanate, lead zirconate, and mixtures thereof, and is formed into a thin plate.
One surface is coated with a conductive material, for example, silver-palladium, which will serve as an internal electrode, and thin plates are laminated, pressed, and sintered to obtain a material for a laminated piezoelectric element. In this case, thin plates are laminated on two opposing sides of the material so that the ends of the internal electrodes are exposed for each layer. Then, after cutting the other two sides perpendicular to the above two sides of the material in the stacking direction to expose the ends of all the internal electrode layers, the two sides where the ends of the internal electrodes are exposed every other layer. coated with conductive material.

It is baked to form a temporary external electrode and a laminated piezoelectric material.

Next, one side of the laminated piezoelectric body on which the ends of all the internal electrode layers are exposed is immersed in an electric field etching solution that corrodes the internal electrodes by applying a voltage, and a voltage is applied via the temporary electrode. An electric current is applied to corrode the ends of the internal electrodes connected to the external electrodes to form recesses in every other layer. The depth of the recess is preferably 50 to 500 μm. In the same way, a recess is formed on the surface where the end of all the layers of the other internal electrode is exposed, and then the recess is filled with an insulator, and then the surface on which the temporary electrode is formed is cut. , expose the ends of all layers of the internal electrodes on two sides perpendicular to the surface where the insulator is embedded (
(Discard the temporary external electrode).

Finally, external electrodes that are electrically connected to the internal electrodes are attached every other layer to the surface where the insulator is embedded, creating a laminated piezoelectric element in which the area of the internal electrode surface and the area of the piezoelectric material surface are substantially equal. Ru.

(Example) The present invention will be explained by way of one embodiment with reference to the drawings.

Embodiment FIG. 6 is a perspective view of a laminated piezoelectric element according to an embodiment of the present invention. In this laminated piezoelectric element, the layers of each piezoelectric material 1 are integrated by sintering via an internal electrode 2, and the internal electrode 2 has an insulating layer 3, 3' at every other layer at its end, and an external They are electrically connected in parallel by electrodes 4.

Next, a method for obtaining this laminated piezoelectric element will be explained.

First, to obtain a multilayer capacitor type multilayer piezoelectric material.

A trace amount of polyvinyl butyral as an organic binder, dioctyl phthalate as a plasticizer, and a mixed solvent of trichloroethane and ethyl alcohol as a solvent are added to the calcined powder of a piezoelectric material whose main components are lead nickel niobate and lead titanate. Mixing was performed in a ball mill for 24 hours to create a slurry. This slurry was then poured onto a polyester film.

Formed into a sheet using the doctor blade method, 280μ thick
A green sheet of m was prepared. After punching this green sheet into a size of 50 x 50 mm, as shown in FIG.
Ag: pd=-y: 3) was screen printed. 50 of these green sheets 13 are stacked with the directions changed by 180 degrees so that the ends of the internal electrodes 2 appear alternately on the opposing sides, and after being crimped and integrated using a heat press, the ends of the internal electrodes 2 are The side surface perpendicular to the exposed side surface was cut to a width of 5 g so that the end of all layers of the internal electrode was exposed. After firing this at 1130℃.

A conductive material was coated and baked on the side surfaces of the internal electrodes 2 where the end portions of every other layer were exposed to form temporary electrodes 8, 8', thereby obtaining a laminated piezoelectric body 9 of a laminated capacitor type.

(Figure 2).

Next, as shown in FIG. 3, one side of the multilayer capacitor type multilayer piezoelectric body 9 on which the end of the internal electrode 2 is exposed is subjected to electrolytic etching using an aqueous solution of potassium ferrocyanide and sodium cyanide in a bath 12. Immerse it in the liquid 10, submerge the graphite counter electrode plate 11 at the same time, connect it and one of the temporary electrodes 8 to the power source S, and apply 2.5 V DC to the electrode plate 11.
When electric field etching was performed for 0 minutes, the exposed end portions of the internal electrodes 2 were corroded every other layer, forming recesses of approximately 100 μm. Next, a concave portion was formed by electric field etching in the same manner on the other side surface of the laminated piezoelectric body where the end portions of all layers of internal electrodes were exposed. Next, an insulating paste (glass paste manufactured by Shoei Chemical Co., Ltd. 9317) was poured into these recesses.

At this time, wipe off the insulating paste adhering to the side surfaces of the laminated piezoelectric body other than the recessed parts, and dry the paste inside the recessed parts at 600°C.
After baking for 10 minutes, the inside of the laminated piezoelectric body 9 was baked as shown in FIG. Insulating layers 3 were formed every other layer at the ends of the internal electrodes on the surface where the ends of all the layers of &2 were exposed.

As shown in FIG. 4, the laminated piezoelectric body 9 produced in this way has a width of 5 mm near and between the temporary electrodes 8 and 8'.
By cutting at the position indicated by the dashed-dotted line in the figure, a laminated piezoelectric body 9' having no external electrodes as shown in FIG. 5 was obtained.

Further, as shown in FIG. 6, a conductive material is applied and baked so that the exposed end of the internal electrode 2 is connected to the surface of the laminated piezoelectric body 9' on which the insulating layer 3 is formed, and the external electrode 4 is formed. It was made into a laminated piezoelectric element.

(Effects of the Invention) According to the present invention, since the area of the internal electrode surface and the area of the piezoelectric material surface are substantially equal, the distribution of strain that occurs when an electric field is applied is uniform and reliable without the risk of destruction. A multilayer piezoelectric element with high properties can be obtained.

Furthermore, according to the present invention, the insulation of every other layer at the end of the internal electrode is performed by forming a recess by electric field etching and then filling the recess with an electrically insulating material. Even if the dimensions of the internal electrodes change, the insulation treatment at the ends of the internal electrodes can be performed extremely efficiently, making it possible to manufacture them with high reliability.

[Brief explanation of the drawing]

Figures 1 to 6 show the laminated mold pressure 1! which is an embodiment of the present invention!
These are diagrams explaining the manufacturing method of the element. Figure 1 shows the state in which internal electrodes are printed and laminated on the piezoelectric material, Figure 2 shows an overview of the laminated piezoelectric material, Figure 3 shows the electrolytic etching method, and Figure 4 shows the insulating layer. Overview of the laminated piezoelectric material formed. FIG. 5 shows a cut state of the laminated piezoelectric body of FIG. 4, FIG. 6 shows a completed laminated piezoelectric element, and FIGS. 7 to 9 are perspective views showing conventional laminated piezoelectric elements. Explanation of symbols 1... Piezoelectric material 2... Internal electrode 3.3'.
...Insulating layer 4...External electrode 5...Lead extraction part of internal electrode 6...Lead wire 7...Metal film 8.8'
...Temporary part electrode 9...Laminated piezoelectric body 10...Electric field etching liquid 11...Counter electrode plate 12...Hinoki 13.
・・Green Sheet/゛Representative Patent Attorney Kunihiko Wakabayashi;1);No a

Claims (1)

[Claims] 1. A process of obtaining a laminated capacitor-type laminated piezoelectric material by forming temporary external electrodes on each of the two opposing sides after integrating the piezoelectric material and internal electrodes by laminating and sintering a plurality of layers alternately; a step of insulating the ends of the internal electrodes exposed on the other both sides of the laminated piezoelectric body every other layer; a step of cutting the insulated laminated piezoelectric body near the temporary external electrode;
A multilayer piezoelectric element comprising the step of forming an external electrode to be connected to an internal electrode on two insulated surfaces of a cut multilayer piezoelectric material, and the area of the internal electrode surface is substantially equal to the area of the piezoelectric material surface. In the manufacturing method, one exposed side surface of the internal electrode of a laminated piezoelectric body is immersed in an electrolytic etching solution, and a voltage is applied to one temporary external electrode to remove the end of the internal electrode connected to the temporary external electrode. By electric field etching, the ends of the inner electrodes on one side surface are made into recesses every other layer, and then, in the same way, the end parts of the inner electrodes on the other side surface, which are connected to the opposing temporary external electrode, are made into recesses every other layer. A method for manufacturing a laminated piezoelectric element, characterized in that the end portions of the internal electrodes are insulated by filling these recesses with an electrically insulating member and forming an insulating layer.