JPH0294484A - Laminated piezoelectric element - Google Patents

Abstract

PURPOSE:To connect the inner electrodes efficiently without fail by a method wherein notch parts disconnecting from outer electrodes are provided in different positions in every layer on the projections or recessions of the inner electrodes while outer electrodes connecting to the inner electrodes are provided in every layer on the projections or recessions of a laminated body. CONSTITUTION:A binding agent and a solvent are added to a calcined powder of piezoelectric material to make a slurry which is fed to a polyester film to form green sheets by doctorblading process. After punching the projections out of the sheets 1, one side of each projection is printed with Ag-Pd paste the inner electrode to leave notch parts 3a, 3b not coated with the paint. Next, fifty green sheets 1 in different printed patterns are alternately heaped with the projections put in order to be formed into one body by pressure fixing process using a thermal press and then the organic binding agent contained in the laminated body is added thereto to be scattered and further baked. Finally, the whole surface is coated with conductive paste 4, 4' to connect the inner electrodes 2 exposed to the projections in every other layer on the sides of the laminated body so that the positive and negative electrodes may be formed by seizing.

Description

[Detailed description of the invention] (Industrial application field) Is the present invention a laminated type pressure? ! ! Regarding the structure of the element.

(Traditional technology) The 9F* layered pressure "fIL element utilizes displacement due to the piezoelectric inverse effect, as shown in Japanese Patent Application Laid-open No. 49-86818, by providing electrodes on a piezoelectric ceramic thin plate and making a large number of them. It has an adhesive laminated structure.As shown in Fig. 6, a piezoelectric ceramic thin plate 1 is provided with an inner part 1Efi2, and two outer electrodes (lead wires 6) arranged on the sides thereof are connected to the inner electrode 2. Every other layer is connected by an extended lead wire outlet 5.

(Problem to be Solved by the Invention) However, in the laminate eζ, if the thickness of the pressed ceramic thin plate 1 is set to 0.5 mm or less, the inner electrode 2
Since it is industrially difficult to connect every other layer, the thickness of the piezoelectric ceramic thin plate has been limited to 0.5 mm or more.

Therefore, the voltage required to drive the laminate is several hundreds of volts or more, which is inconvenient.

Therefore, in recent years, in order to obtain a monolithically fired laminated piezoelectric element that is compact and can be driven at a low voltage, a thickness of 0.03 to 0.5 a has been developed.
After printing the Kl polar paste on one side of the ceramic green sheet of m, many sheets of this were thermo-compressed and then fired.
Furthermore, attempts were made to apply the technology of multilayer capacitors obtained by forming external electrodes, and it became possible to lower the driving voltage. However, the multilayer capacitor type multilayer pressure '1jt
As shown in FIG. 7, the element consists of two opposing 9 (9) (11) faces of a stacked body of piezoelectric ceramic thin plates 1, since the two positive and negative internal electrodes 2 do not overlap near the nucleus side.
The part is piezoelectrically inactive and does not displace even in °C when a 1f field is applied, thus clamping the displacement of the piezoelectrically active part.

As a result, there was a drawback that the displacement r# of the element itself was small.

To solve this problem, as shown in FIG.

If the area of each internal electrode 2 and the area of the layer of the piezoelectric ceramic thin plate 1 are made the same, the amount of displacement of the piezoelectric element will increase because there will be no pressure-inactive part inside the inverter. If the pressure Ir1. Ceramic thin plate iVi number lO
Since the thickness is as thin as ~100 μm, it becomes difficult to industrially connect the poles of each internal layer every other layer. That is, 1. For example, as shown in Japanese Unexamined Patent Application Publication No. 58-196068, an insulating paste is printed on the end of the internal electrode.
It is fired to form an insulating layer.

One possible method is to form a conductive material layer (external electrode) on top of it, but in this case, there is a problem that the reliability of the parallel connection of the internal electrodes becomes insufficient even if there is a slight positional deviation of several tens of micrometers. . I cut it.

Even if the parallel connection of internal electrodes is successfully made.

There is a problem in that stress concentration occurs between the laminated portion that is displaced by the application of an electric field and the external electrode that is not displaced, and that the external electrode is broken due to the reciprocal application of the electric field.

In view of the above-mentioned problems, the present invention makes it possible to reliably and efficiently connect every other layer of internal electrodes even when the interval between internal electrodes is small, and also provides 1! It is an object of the present invention to provide an element whose displacement amount is large when a field is applied.

(Means for Solving the Problems) The present invention provides a method in which a plurality of piezoelectric ceramic thin plates are sintered and integrally fixed to each other through internal electrodes having substantially the same shape as the piezoelectric ceramic thin plates. In a jet type piezoelectric element having a pair of positive and negative external electrodes connected to electrodes alternately every other layer, the laminate has a convex part or a concave part at one place on the fl11 surface, and the convex part or four parts are Piezoelectric ceramic thin plate and internal electrode (convex part provided on the outer periphery of the
'F layer is good, and every other convex part or four parts of the internal electrode is provided with a notch insulating from the external electrode at the position of the V crystal, and -J! The present invention relates to a laminated piezoelectric element having a pair of external electrodes connected to an internal electrode every 7 times.

For the present invention, the materials of the FET 1f ceramic thin ball are nickel lead niobate, lead titanate, and lead zirconate.

There is no restriction on the mixture as long as it has an excellent isoelectrostrictive effect. A laminate consisting of a piezoelectric ceramic thin plate and an internal 'p+t pole is torn in the following manner: 1). Said pressure '1! ! A green sheet is prepared using a known slurry containing the material by a doctor blade method or the like, and the green sheet is struck once so that the convex portions 3 are submerged as shown in FIG. 2, for example.
Is one side of this green sheet coated with conductor paint such as silver-palladium? n :l L? 'The internal electrode 2 is formed as shown in J. In this case, as shown in Fig. 3 (a) and (b) K, the same number of sheets are prepared with the parts (notches) 3a and 3b where the conductive paint is not applied, and after drying, the same number of sheets are prepared. It is fired to form an fRNi body as shown in FIG.

Next, for example, a four-layer paste is applied as shown in 4.4' on both sides of the convex portion 3, and positive and negative external electrodes connected to the internal electrodes are formed every other layer.

To make a laminate having four parts, a green notebook is punched out, for example, as shown in FIG. 4, and cutout parts 7a and 7b where the conductor ends and #+2 are not painted are formed.

Thereafter, these thin plates are laminated, thermocompressed, dried, and fired.

Although the shape of the piezoelectric ceramic thin plate is rectangular in the one shown in FIG. 2, it is not limited to this, and may be circular, oval, or the like. It is better for jJ to be thinner, but there is no particular limit.

(Example) Next, the present invention will be explained with reference to embodiments.

Figure 1 shows an example of the present invention.+FI layer type pressure? It is a perspective view of Jiang Songzi. In this embodiment, each piezoelectric ceramic thin plate 1 and each internal electrode 2 are integrated by sintering,
Each internal one electrode is alternately connected in parallel to positive and negative external electrodes at the convex portion of the laminate (1111 plane).

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

First, 9. Finely divided polyvinyl butyral as an organic binder, dioctyl phthalate as a plasticizer, and a mixed solvent of trichloroethane and ethanol as a solvent were added and mixed in a ball mill for 24 hours to prepare a slurry.

Next, this slurry was poured onto a polyester film and 7-t molded using a doctor blade method.

A green sheet with a thickness of 220 μm was produced. This green sheet, k, is punched into a shape of 10 mm square with one protrusion 3 having a width of 2 mm and a length of 2 - on the outer periphery as shown in Fig. 2.
g-Pd paste (Ag, Pd-7:3) in Figure 3fa
Screen printing was performed with the patterns shown in + and (bl). Fifty green sheets with different printing patterns were stacked alternately with the convex portions 3 aligned, and after being pressed and integrated using a hot press, the organic material in the laminate was The binder was dispersed by heating and then fired by heating to 1130°C.

Conductive paste (manufactured by Shoei Chemical Co., Ltd.) was used to connect the internal electrodes 2 exposed in every other layer of the piezoelectric ceramic thin plate shown in FIG. 1 to the side convex portions of the laminate after firing.

Silver paste H4170) was applied and baked as shown in 4.4' in FIG. 1, and positive and negative external electrodes were formed to form a laminated piezoelectric element. The displacement characteristics of this element are shown in FIG. 5 together with an example of a conventional multilayer capacitor structure shown in FIG. Fruit from Figure 5! It is shown that the displacement amount with respect to the voltage is smaller than that of the conventional case in the row A.

(Effects of the Invention) According to the present invention, even if the thickness of the piezoelectric ceramic thin plate is thin and the interval between internal electrodes is small, connection between every other internal layer can be performed reliably and efficiently. However, the amount of displacement of the laminated piezoelectric element can be increased even at a voltage lower than that of the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway view of a laminated piezoelectric element according to an embodiment of the present invention. Figure 1 is a plan view of the green sheet punched out during the manufacture of the laminated mold pressure element. Figures 3 and 4 are plan views illustrating the state of formation of the internal electricity, and Figure 5 is the voltage and voltage. Graph showing the relationship with the amount of displacement, No. 6
7 and 8 are perspective views of conventional laminated piezoelectric elements. Fig. 1 (b) 3... Convex portion 4... Lead > It paste 5... Lead wire extension part 6... Lead wire P7.
・・Notch part 11・・7” J-Rule-1-￥
15 Oral agent Patent attorney Kunihiko Wakabayashi Jr. (Hisashi) (b) I

Claims (1)

[Claims] 1. A pair of positive and negative external electrodes are connected to the side surface of a laminate in which a plurality of piezoelectric ceramic thin plates are sintered and integrated via internal electrodes having substantially the same shape as the piezoelectric ceramic thin plates, and are connected to the internal electrodes alternately every other layer. In the laminated piezoelectric element, the laminated body has a convex portion or a concave portion at one location on the outer periphery of the side surface, and the convex portion or the concave portion is a convex portion or a concave portion provided on the outer periphery of the piezoelectric ceramic thin plate and the internal electrode. It is a stack of concave parts, and the convex part or concave part of the internal electrode is provided with a notch insulating from the external electrode at a different position on every other layer, and the convex part or concave part of the laminate is connected to the internal electrode every other layer. A laminated piezoelectric element equipped with a pair of external electrodes.