JPH0831631B2 - Electrostrictive effect element - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrostrictive effect element having a laminated structure.

[Prior Art] Conventionally, this type of electrostrictive effect element has a structure as shown in FIG. That is, for example, a sheet formed by adding a trace amount of an organic binder to powder of an electrostrictive material containing lead zirconate titanate as a main component, dispersing this in an organic solvent to form a slurry, and forming a film by a tape casting method. Alternatively, a thin plate (hereinafter abbreviated as an electrostrictive sheet) 1 is formed, and a conductor paste containing a mixture of silver powder and palladium powder as a main component is applied to one surface of the electrostrictive substrate 1 by screen printing or the like. The formed internal electrode conductor (hereinafter abbreviated as an internal electrode) 2 is formed, and a plurality of these are laminated to form a laminated body, and the insulator 3a is formed on the internal electrode 2 exposed on the side surface thereof every other layer. Then, the first external electrode 4a is formed from above. On the other hand, on the side surface opposite to the side surface, the insulator 3b is selectively formed on the exposed portion of the internal electrode 2 where the insulator was not previously formed, and the second external electrode 4b is formed thereon. Then, the lead wires 5a, 5b were connected to the external electrodes 4a, 4b on both side surfaces by solders 6a, 6b.

Further, as shown in FIG. 5, there is also a structure in which an electrostrictive sheet 1 which does not have one or more layers of internal electrodes attached thereto is inserted in the portions located under the solders 6a and 6b.

These conventional electrostrictive effect elements pass through the internal electrodes 2 when a voltage is applied between the external terminals A and B of the voltage supply unit (not shown) through the lead wires 5a and 5b and the external electrodes 4a and 4b. Then, a voltage is applied to both ends of all the electrostrictive sheets 1, and strain is generated in the X direction shown in the figure as the entire device.

[Problems to be Solved by the Invention] In the above-described conventional electrostrictive effect element, when the electrostrictive sheet 1 is thinned to, for example, 250 μm or less, a sufficient space for depositing the solders 6a and 6b cannot be taken. Solder 6a, 6b
Is applied on the insulators 3a, 3b and gives thermal stress, or the solder suppresses distortion, so that the insulator is easily broken when the element is driven, which is a major drawback in reliability. The electrostrictive effect element having the structure shown in FIG. 5 for ensuring the above is apt to be damaged by the insulators 3a and 3b or the element itself due to the non-uniform internal stress distribution generated by the electrostriction. After all, there is a defect in reliability.

[Means for Solving the Problems] The electrostrictive effect element of the present invention includes a laminated sintered body in which sheet-shaped piezoelectric ceramic members and internal electrode conductors are alternately laminated, and the pair of opposed laminated sintered bodies are opposed to each other. One end surface of the internal electrode conductor exposed on the side surface of the internal electrode conductor is alternately insulated on the pair of side surfaces by an insulator, and the other end portion of the internal electrode conductor which is not insulated is provided on each side surface of the external electrode. In the electrostrictive effect element in which the lead wire is connected to the external electrode, the internal electrode conductor provided in the region of the external electrode to which the lead wire is connected has an end portion led to the outside. Formed by cutting out,
Of the plurality of ends of the internal electrode conductor in the region, the end that is to be in contact with the external electrode is electrically connected to the external electrode outside the cutout and should not be in contact with the external electrode. The end portion of the inner electrode conductor is electrically insulated by the insulator except for the cutout portion facing the outer electrode.

[Operation] By providing a conductor deficient portion at a part of the inner electrode conductor end portion, a sufficient space for soldering can be provided at an arbitrary location, and the nonuniformity of internal stress distribution caused by electric strain can be minimized. Since this can be suppressed, the electrostrictive effect element has a structure that does not destroy the insulator and the element itself.

Example Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of an embodiment of the electrostrictive effect element of the present invention,
2 is a perspective view of the laminated body 10 of FIG. 1 cut along the internal electrode 2X portion, and FIG. 3 (a) is an internal electrode in which a square defect is provided in the central portion of the opposing side surfaces of the internal electrode. FIG. 2 is a perspective view showing 2X and electrostrictive sheet 1X.

The laminated sintered body 10 of the electrostrictive effect element according to this embodiment has a rectangular shape at a desired number of electrostrictive sheets 1 and lead wires 5a and 5b to be soldered, as shown in FIG. 3 (a). Is a prismatic shape obtained by laminating three electrostrictive sheets 1X to which internal electrodes 2X having a pattern having a defect portion are laminated, integrated by thermal pressing, and sintered at a temperature of about 1100 ° C. for about 2 hours. .

Internal electrodes 2, 2X exposed on the first side surface of the laminated sintered body 10
Insulators 3a such as glass are formed on every other layer, and the internal electrodes 2 exposed on the second side surface facing the first side surface,
Of 2X, an insulator 3b such as glass is formed on the internal electrode that is not insulated on the first side surface. An external electrode 4a coated with a conductive paste containing silver powder as a main component is formed on the first side surface. In the figure, a blind spot is formed so that it cannot be seen, but a similar external electrode 4b is also formed on the second side surface. Lead wires 5a and 5b connected by solder 6 are provided on the external electrodes 4a and 4b and at positions where the electrodes are not exposed by the internal electrodes 2X.

The electrostrictive effect element of the present embodiment is the external electrodes 4a, 4b from the external terminals of the voltage supply unit (not shown) via the lead wires 5a, 5b.
When a voltage is applied between the internal electrodes 2a and 2b, a voltage is applied to both ends of all the electrostrictive sheets 1 and distortion occurs in the X direction of the arrow as a whole of the element.

FIG. 3 (b) shows an internal electrode 2Y having a semicircular defect portion.
FIG. 3 is a perspective view of an electrostrictive sheet 1Y having This internal electrode 2Y
Is the internal electrode 2X with the square defect described above.
Similarly used in the present invention.

Next, an experiment conducted on the electrostrictive effect element of the present invention having a width and depth of 10 mm and a height of 20 mm and the results thereof will be described. In addition to the conventional element shown in FIG. 4, the elements shown in the above-mentioned two embodiments each having five levels (reference numerals A to J), respectively.
I prepared 20 pieces. The five levels are shown in Table 1, and the area of the electrodeless pattern is changed.

These devices were driven for 2 billion times with a pulse voltage of 150 V and 1 KHz, and examined for defects. Table 2 shows the number of defectives and defective points.

As can be seen from Table 2, in any of the examples, the levels A and B, that is, the length of the side facing the side surface is 3 mm.
In the following cases, the occurrence rates of both glass breakage and device breakage are smaller than those of conventional devices. The area of the electrodeless pattern is limited by the element cross-sectional area and the soldering area, but it is preferably about 1/20 of the cross-sectional area. Further, the element breakdown was less likely to occur in the semicircular pattern shown in the later-described examples than in the rectangular pattern shown in the first-mentioned examples.

EFFECTS OF THE INVENTION As described above, according to the present invention, the internal electrode is formed at an arbitrary position of the electrostrictive effect element so that a part of the internal electrode conductor is not exposed on the side surface of the element. Is sufficient, and it is possible to prevent the breakdown of the insulating material due to the effect of suppressing the thermal stress at the time of solder formation and the distortion of the solder, which has a great effect on the miniaturization of the element and the improvement of reliability.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the electrostrictive effect element of the present invention, and FIG. 2 is a perspective view showing the external electrodes and insulators of FIG. 1 removed.
FIGS. 3 (a) and 3 (b) are perspective views cut along the YZ plane, showing perspective views of internal electrode conductors used in the examples of the present invention, and FIGS. It is sectional drawing which shows the example of a strain effect element. 1 ... Electrostrictive sheet, 1X, 1Y ... Electrostrictive sheet (with defect internal electrode) 2 ... Internal electrode, 2X, 2Y ... Internal electrode (with defect) 3a, 3b ... Insulator, 4a, 4b ... External electrode, 5a, 5b ... Lead wire, 6a, 6b ... Solder, 10 ... Layered sintered body, A, B
...... External terminal.

Claims (1)

[Claims] 1. A laminated sintered body, in which a sheet-shaped piezoelectric ceramic member and an internal electrode conductor are alternately laminated, wherein one end face of the internal electrode conductor exposed on a pair of opposing side surfaces of the laminated sintered body is the above-mentioned. The pair of side surfaces are alternately insulated by an insulator, and the other end of the internal electrode conductor that is not insulated is connected to an external electrode provided on each of the side surfaces, and a lead wire is connected to the external electrode. In the electrostrictive effect element, the internal electrode conductor provided in a region to which the lead wire of the external electrode is connected is formed by cutting out an end portion led out to the outside, and the internal electrode conductor in the region is formed. Of the plurality of end portions of the inner electrode conductor, the end portion of which is to be in contact with the external electrode, is electrically connected to the outer electrode outside the cutout portion, and is not to be in contact with the outer electrode. Is electrically insulated by the insulator except the cutout portion facing the external electrode.