JPH04243173A - Electrostrictive effect element - Google Patents

Abstract

PURPOSE:To improve yield of element manufacturing steps and to improve reliability of the element by so forming outer electrodes formed on both upper and lower end faces of a multilayered sintered body as to be smaller than profiles of both upper and lower end faces of the sintered body. CONSTITUTION:30 electrostrictive sheets 1 on which inner electrodes 2 are not printed, 120 electrostrictive sheets on which the electrodes are printed, and further 30 electrostrictive sheets 1 on which the electrodes are not printed, are sequentially stacked, thermally pressed to be integrated, and sintered. After the sintered body is sliced in a rectangular state, glass insulators 3a, 3b are alternately formed on the electrodes 2 every other layers. The surface is covered with high temperature baking type paste, dried, and then baked to form outer electrodes 4a, 4b. Further, both the upper and lower end faces are also so covered with the same paste in an independent pattern inside from the profile of the end face of an element so as not to dispose the cut part on the pattern at the time of cutting, dried, and then baked to form outer electrodes 5a, 5b of the end faces.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostrictive element having a laminated structure, and more particularly to the structure of its external electrode.

0002

[Prior Art] A conventional electrostrictive effect element is disclosed in Japanese Patent Application Laid-Open No. 59-21
9972, it had the structure shown in FIG. That is, electrostrictive sheets 1 and internal electrodes 2 are alternately laminated, the internal electrodes 2 are alternately covered with glass insulators 3a and 3b on a pair of opposing sides, and external electrodes 4a and 4b (
A blind spot in the figure) was formed and connected to end surface external electrodes 5a and 5b formed on the entire upper and lower end surfaces, respectively.

0003

The conventional electrostrictive effect element described above is manufactured according to the process flowchart shown in FIG. That is, an internal electrode paste is applied to an electrostrictive ceramic sheet formed into a sheet, cut into a regular shape, laminated, pressed, and then sintered. The obtained sintered body is sliced into strips, a glass insulator and an external electrode are formed in this order, and then cut into a certain size to form an element. FIG. 5 shows a slice immediately before cutting into elements, and external electrodes are formed on the entire end face of the slice so that external electrodes on both the upper and lower end faces of the element are formed on the entire end face. Therefore, when this slice is cut into devices, a portion of the end surface external electrode on the cutting line is likely to peel off due to the impact during cutting, resulting in poor appearance and lower yield, as well as peeled off external electrode pieces and scraps. adheres to the cut surface, causing short circuits between internal electrodes and deteriorating the initial characteristics and reliability of the device. Furthermore, when elements are used by bonding each other or an element and a member, the tensile strength is determined by the adhesion strength between the external electrode and the ceramic, and there may be insufficient strength.

[0004] An object of the present invention is to provide an electrostrictive element that does not cause peeling defects of end face external electrodes, reduces short-circuit defects and initial defects, and improves reliability compared to conventional devices. It's about doing.

[0005]

[Means for Solving the Problems] The electrostrictive effect element of the present invention has internal electrode conductors exposed on a pair of opposing sides of a laminated sintered body in which sheet-like piezoelectric ceramic members and internal electrodes are alternately stacked. One end of the internal electrode conductor is alternately insulated by an insulator on the pair of side surfaces, and the other uninsulated end of the internal electrode conductor is connected to an external electrode provided for each of the side surfaces, In an electrostrictive effect element in which a pair of external electrodes are respectively connected to external electrodes formed on both upper and lower end surfaces of the laminated sintered body, the external electrodes formed on both upper and lower end surfaces of the laminated sintered body are connected to the It has the characteristic that it is formed smaller than the outer shape of both the upper and lower end surfaces of the laminated sintered body.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the present invention. 1 in the figure shows, for example, a powder of a piezoelectric material whose main component is lead zirconate titanate Pb(Ti,Zr)O3, a trace amount of an organic binder is added, and this is dispersed in an organic medium to form a slurry. This is an electrostrictive sheet formed to a thickness of about 130 μm by tape casting. Reference numeral 2 denotes an internal electrode formed on the electrostrictive sheet 1. A paste containing a 7:3 mixture of silver and palladium powder was deposited on the electrostrictive sheet 1 to a thickness of about 10 μm by screen printing.

Next, 30 electrostrictive sheets 1 on which internal electrodes 2 were not printed, 120 electrostrictive sheets on which the internal electrodes 2 were printed, and further 30 electrostrictive sheets on which no internal electrodes were printed were laminated in order.
00kg/cm2 and heat and press to integrate, approx.
Sintering was carried out at a temperature of 100° C. for 2 hours. After slicing this sintered body into strips, glass insulators 3a and 3b were formed every other layer on the internal electrodes 2 on the exposed surfaces of the internal electrodes so as to alternate on the front and back sides. A high-temperature firing type paste containing silver as the main component was formed on this surface by screen printing to a thickness of approximately 30 μm, and after drying,
After baking at ℃ for 10 minutes, external electrodes 4a and 4b (blind area in the figure)
was formed. Furthermore, the same paste was applied to both the upper and lower end surfaces in an independent pattern that was 0.2 mm inside the outer shape of the end surface of the element so that the cut portion would not overlap the pattern when cutting, and after drying, it was baked at 600°C for 10 minutes. , end surface external electrodes 5a and 5b (blind areas in the figure) were formed. Thereafter, the rectangular sintered body in which the glass insulator, external electrodes, and end surface external electrodes were formed was cut into small pieces to obtain the electrostrictive element 10.

FIG. 2 shows a second embodiment of the present invention. This embodiment differs from the first embodiment in that the end surface external electrodes 5a,
It was manufactured in the same manner as the first example except that the shape of 5b (blind spot in the figure) was formed on a semicircle. The device of this example is
Since the exposed area of the ceramic is larger than the element of the first embodiment, it has the characteristic that sufficient strength can be obtained when bonding with other elements or members.

In the devices manufactured according to the first and second embodiments, peeling defects of the end external electrodes, which conventionally occurred with a probability of 5%, did not occur at all. In addition, compared to conventional elements, short-circuit defects and initial defects are reduced, and reliability is improved.

0010

As explained above, the present invention has the effect of improving the yield of the device manufacturing process and improving the reliability of the device by forming the external electrode on the device end surface to be smaller than the outer diameter of the device end surface. There is. Furthermore, when an element is attached and used, it has the effect of improving tensile strength.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of the invention.

FIG. 2 is a perspective view of another embodiment of the invention.

FIG. 3 is a perspective view of an example of a conventional electrostrictive effect element.

FIG. 4 is a flowchart showing a manufacturing process of an electrostrictive element.

5 is a perspective view showing a state before cutting of a conventional electrostrictive effect element manufactured according to the flowchart of FIG. 4; FIG.

[Explanation of symbols]

1 Electrostrictive sheet 2 Internal electrode 3a, 3b Glass insulator 4a, 4b External electrode 5a, 5b End surface external electrode 10 Electrostrictive effect element

Claims (1)

[Claims] 1. One end of an internal electrode conductor exposed on a pair of opposing side surfaces of a laminated sintered body in which sheet-like piezoelectric ceramic members and internal electrodes are alternately stacked is alternately arranged on the pair of side surfaces. The other end of the internal electrode conductor that is insulated by an insulator is connected to an external electrode provided on each side surface, and the pair of external electrodes are connected to both upper and lower ends of the laminated sintered body. In an electrostrictive effect element connected to external electrodes formed on each surface, the external electrodes formed on both upper and lower end surfaces of the laminated sintered body are formed smaller than the outer diameter of both upper and lower end surfaces of the laminated sintered body. An electrostrictive effect element characterized by: