JPS60154581A - Laminated piezoelectric body and manufacture thereof - Google Patents

Abstract

PURPOSE:To eliminate the possibility of breakdown against the repeated application of an electric field by forming an insulating layer at the end section of an internal electrode so that the area of the internal electrode and the crosssectional area of a piezoelectric layer substantially equalize. CONSTITUTION:Each piezoelectric body layer 7 is coupled integrally by sintering through internal electrodes 8 in a laminated piezoelectric body 6. The end sections of the electrodes 8 have insulating layers 9 at every other layer, and the electrodes 8 are connected electrically in parallel by external electrodes 10. The piezoelectric body 6 takes a prismatic shape of 2mm.X3mm.X9mm., and the piezoelectric layers 7 in approximately 180mum thickness are laminated by fifty layers through the electrodes 8. The layer 9 is formed on the side surface of a rectangle of 2mm.X9mm. of the piezoelectric body 6 as a layer in 100mum depth X 100mum width. In the piezoelectric body 6 constituted in this manner, the areas of the electrodes 8 and the crosssectional areas of the layers 7 substantially equalize. Accordingly, the distribution of strain generated on the application of an electric field is made uniform, and the piezoelectric body, in which there is no possibility of breakdown and which has high reliability, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laminated piezoelectric material and a method for manufacturing the same.

Background technology and its problems In order to obtain a monolithically fired laminated piezoelectric material that is compact and can be driven at low voltage, attempts have been made to apply a manufacturing technology for laminated capacitors that does not use adhesives, called the green sheet lamination method. ing. With this manufacturing technology, it is possible to easily reduce the distance between internal electrodes, which is considered to be a minimum of about 500 μm in laminated piezoelectric materials using adhesives, for example, 50 to 50 μm.
The thickness can be set to 0 μm, and as a result, the driving voltage can be lowered. However, in a multilayer capacitor type multilayer piezoelectric material, the area of each internal electrode 1 is smaller than the cross-sectional area of the piezoelectric material layer 2a of the piezoelectric material 2, as shown in FIG. becomes uneven,
The disadvantage is that it is easily destroyed.

In order to eliminate this drawback, as shown in FIG. 2, if the area of each internal electrode 6 and the cross-sectional area of the piezoelectric layer 4a of the piezoelectric body 4 are made equal, the strain distribution inside the piezoelectric body 4 becomes uniform, and therefore Although no damage occurs even when an electric field is repeatedly applied, in this case, in order to connect the can internal electrodes in parallel, it is necessary to insulate the ends of each internal electrode 6 every other layer. This insulation treatment is extremely difficult when the distance between internal electrodes is as small as, for example, 50 to 600 μffl.

Purpose of the Invention In view of the above-mentioned points, the present invention provides a laminated piezoelectric material in which the area of the internal electrode and the cross-sectional area of the piezoelectric material layer are substantially equal, and there is no risk of destruction due to repeated application of an electric field. It is.

The present invention further provides the advantage that even when the distance between internal electrodes is small,
The present invention provides a method for efficiently insulating the ends of internal electrodes and manufacturing a laminated piezoelectric body with high productivity.

Summary of the Invention The laminated piezoelectric body of the present invention consists of an element in which a plurality of piezoelectric layers are integrated by sintering through internal electrodes, and an external electrode, with the ends of the internal electrodes being spaced apart on both sides of the element. In a laminated piezoelectric body that is insulated and has internal electrodes electrically connected in parallel by external electrodes, the end of the internal electrode has an insulating layer on both sides of the element, and this insulating layer is The size is such that the cross-sectional area of the piezoelectric layer is substantially equal to the cross-sectional area of the piezoelectric layer. In this laminated piezoelectric body, since the area of the internal electrode and the cross-sectional area of the piezoelectric layer are substantially equal, the distribution of strain inside the piezoelectric body that occurs when an electric field is applied is uniform, which is different from that in the case of a laminated ceramic capacitor type piezoelectric body. 1 can be achieved by solving the problem of destruction, and high reliability can be obtained.

In addition, the method of the present invention includes a step of preparing an element of a predetermined size in which a plurality of piezoelectric layers are integrated by sintering through internal electrodes, and a step of preparing an element of a predetermined size in which a plurality of piezoelectric layers are integrated by sintering through internal electrodes, and a step of preparing an element of a predetermined size in which a plurality of piezoelectric layers are integrated by sintering through internal electrodes, The process includes a step of insulating the piezoelectric layer, and a step of soaking external electrodes on both sides and surfaces of the element to make electrical parallel connections between the internal electrodes. In a method of manufacturing a laminated piezoelectric material having substantially the same area, grooves are formed in every other layer at the ends of internal electrodes exposed on both sides of the element, an insulator is buried in the grooves, and an insulating layer is formed by baking. This consists of insulating the ends of the internal electrodes.

In the method of the present invention, the dimensions of the groove at the end of the internal electrode vary depending on the dimensions of the intended laminated piezoelectric body, but the blade thickness is 50 mm.
Preferably, it is formed to a depth of 50 to 150 μm using a cutter of ~100 μm, such as an automatic cutting machine.

Next, embodiments of the present invention will be described with reference to the drawings.

Example 1 FIG. 3 is a perspective view of a laminated piezoelectric body according to this example. In this laminated piezoelectric material 6, each piezoelectric material layer 7 has each internal electrode 8.
They are joined together by sintering. Internal electrode 8
has an insulating layer 9 every other layer at its end, and external electrodes 10
are electrically connected in parallel.

This laminated piezoelectric body 6 has a prismatic shape of 2 m x 3 m x 9 m, and 50 piezoelectric layers 8 having a thickness of about 180 μm are laminated with internal electrodes 8 interposed therebetween. Insulating layer 9 consists of 2 pieces of piezoelectric material 6 x 9
It is formed as a 100 μm deep x 100 μm wide layer on the rectangular side of the fin.

In the laminated piezoelectric body 6 configured in this way, the area of the internal electrode 8 and the cross-sectional area of the piezoelectric layer 7 are substantially equal.

Example 2 An example of the method for manufacturing the laminated piezoelectric body described in Example 1 will be described with reference to FIG.

PbO,985Bin,01 (Zno+o42Nio
,12s Nbo, us)Tio0g2Zr(1,,o
To 100 parts by weight of a calcined powder of PZT piezoelectric material having the composition of
Part by weight, 0.5 sorbitan sesquiolate as dispersant
Parts by weight and 10 parts by weight of trichlorethylene and 15 parts by weight of ethyl alcohol were added as a solvent and mixed in a ball mill for 24 hours to prepare a resin.

Next, this resin was poured onto a polyester film, formed into a sheet using a doctor blade, and air-dried to produce a green sheet with a thickness of 250 μm.

Next, 50 circular sheets with a diameter of 20 mvt were punched out from this green sheet, and palladium paste was printed on one side of each circular sheet for internal electrodes.

Stacking these circular sheets, 1000kg/am2
The pressure was applied to integrate the parts, and then the pressure was removed.

Next, this integrated laminate was heated to 700°C at a temperature increase rate of 40°C/11 in an oxygen atmosphere and held at this temperature for 10 hours to decompose and remove the organic binder, sizing agent, and dispersant. After that, it was further heated and held at 1200°C for 6 hours to form a sintered body.

Next, cut this sintered body into 2w+mx3msx9am
A prismatic sintered body element 11 was obtained (No. 418).

Each layer of this element 11 has a blade thickness of 100 mm at the end of the internal electrode 16 exposed on the PZT ceramic layer 129 (rectangular surface).
Every other layer was cut using a μ automatic cutting machine to form grooves 14 with a depth of 100 μm (FIG. 4B).

Next, insulator paste (Dupont 9) is applied to this groove 14.
950 glass paste) was poured. At this time, groove 1
The insulating paste adhering to the side surfaces of the elements other than No. 4 was completely wiped off. After drying the insulating paste in the groove 14, 850
Baking was performed at .degree. C. for 10 minutes to form insulating layers 15 every other layer on both sides of the element 11 (FIG. 4C).

Next, silver paste was printed for external electrodes on both sides of the element including the insulating layer 15, and baked at 700° C. for 10 minutes to form external electrodes 16 to obtain a laminated piezoelectric body 17 (Fig. 4D). ).

After poling was performed by applying a DC voltage with an electric field strength of 12 kV/c11L to the laminated piezoelectric body 17 at 50° C. for 60 minutes, a DC voltage of 100 V was applied, and as a result, the displacement in the height direction was 4 μ.

Effects of the Invention As described above, according to the present invention, an insulating layer is provided at the end of the internal electrode so that the area of the internal electrode and the cross-sectional area of the piezoelectric layer are substantially equal. The body has a uniform distribution of strain that occurs when an electric field is applied, and is highly reliable with no risk of destruction.

Furthermore, according to the present invention, the insulating layer is formed by forming a groove at the end of the internal electrode and burying an insulator in this groove, so the groove can be formed using a cutter with a thin blade. Therefore, even when the distance between the internal electrodes is small, the insulation treatment of the end portions of the internal electrodes can be performed extremely efficiently, and it is possible to manufacture a laminated piezoelectric body with high productivity.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views showing a conventional example, FIG. 6 is a partially cutaway perspective view showing an embodiment of the laminated piezoelectric material of the present invention, and FIG.
The figure shows an embodiment of the method for manufacturing a laminated piezoelectric body according to the present invention. In addition, in the symbols used in the drawings, 6.........Laminated piezoelectric material 7...
・・・・・・・・・・・・Piezoelectric layer 8 ・・・・・・
・・・・・・・・・Internal electrode 9 ・・・・・・・・・・・・
...Insulating layer 10...External electrode 11...Sintered element 1
2・・・・・・・・・・・・・・・PZT ceramic layer 13・・・・・・・・・・・・・・・Internal electrode 14・
・・・・・・・・・・・・・・・Groove 15・・・・・・・・・
. . . Insulating layer 16 . . . External electrode 17 . . . Laminated piezoelectric material. Agent Katsu I Ueya Yoshio Tsuneko αQ

Claims (1)

[Claims] 1. Consisting of an element in which a plurality of piezoelectric layers are integrated by sintering through internal electrodes, and an external electrode, the ends of the internal electrodes are insulated every other layer on both sides of the element. has been,
In a laminated piezoelectric body in which internal electrodes are electrically connected in parallel by external electrodes, the end portion of the internal electrodes has an insulating layer on both sides of the element, and this insulating layer has the area of the internal electrode and the cross-sectional area of the piezoelectric layer. 1. A laminated piezoelectric material having a size such that the values are substantially equal. 2. A step of preparing an element of a predetermined size in which a plurality of piezoelectric layers are integrated by sintering via internal electrodes, and a step of further applying the piezoelectric layer to the end portions of the internal electrodes exposed on both sides of the element. In this method of manufacturing a laminated piezoelectric material in which the area of the internal electrode and the cross-sectional area of the piezoelectric material layer are substantially equal, grooves are formed every other layer at the ends of the internal electrodes exposed on both sides of the element, and an insulating layer is formed in the grooves. 1. A method of manufacturing a laminated piezoelectric material, which comprises insulating the ends of internal electrodes by embedding a piezoelectric material and forming an insulating layer by baking.