JPH04151884A - Multilayer piezoelectric device - Google Patents

Abstract

PURPOSE:To protect a lead wire from falling off and hence enhance reliability by forming a solder land which connects with each outside electrode on the surface of a specified piezoelectric ceramics and bonding said lead wire with the solder land. CONSTITUTION:A solder land 12 is formed on the surface of a piezoelectric ceramics 5a on the lower end and connected with outside electrodes 31 and 32 where lead wires 41 and 42 are bonded with the solder land 12. Since the piezoelectric ceramics 5a is bonded with each lead wire 41 and 42 by way of the solder land 12, the vibration of the lead wires 41 and 42 does not act on the outside electrodes 31 and 32 whose bonding force is weak. This construction makes it possible to protect the outside electrodes 31 and 32 on the connected parts of the lead wires from removal definitely and hence obtains a high reliability multilayer piezoelectric device.

Description

[Detailed Description of the Invention] [Summary] The purpose of this invention is to improve the reliability of a laminated piezoelectric element used as an actuator in a printer by preventing the lead wire connection portion from peeling off due to drive vibration when the piezoelectric element is used. A plurality of piezoelectric ceramics are laminated via internal electrodes to form a columnar body, and a pair of external electrodes are provided on the circumferential surface of the columnar body and alternately connected to each of the internal electrodes. In a multilayer piezoelectric element in which each of the external electrodes is connected to a lead wire, a solder land that connects to each of the external electrodes is formed on a predetermined surface of the piezoelectric ceramic, and the lead wire is connected to the solder land. The structure is such that they are joined directly or through solder.

[Industrial application field]

The present invention relates to a laminated piezoelectric element used as an actuator for a printer.

In recent years, there has been a growing need for ultra-high printing speeds for printers. To meet this demand, it is necessary to use an actuator that responds at high frequencies, and multilayer piezoelectric elements are promising.

On the other hand, printers are used in a wide range of applications, from business use to personal use, and are required to have sufficient reliability under the conditions of use. Therefore, it is an important issue to improve the reliability of printers by providing a laminated piezoelectric element that can achieve high reliability even under poor humidity conditions.

[Conventional technology]

FIG. 5 is a perspective view showing the structure of a conventional laminated piezoelectric element. In the figure, 2 is a columnar body, 33, 3° is an anode/cathode external electrode, 40, 4 □ is a Riet wire, and these constitute the laminated piezoelectric element 1.

The columnar body 2 is formed by laminating a plurality of piezoelectric ceramics 5 with internal electrodes 6 interposed therebetween.

The external electrodes 31, 3□ are formed on opposing circumferential surfaces of the columnar body 1 and are alternately connected to the internal electrodes 6.

These external electrodes 3I, 3□ are formed by screen printing and baking a conductive paste. Reference numeral 7 denotes an electrically insulating layer made of glass or the like that insulates the exposed portion of the internal electrode 6 to the circumferential surface of the columnar body that is not connected to each external electrode 3I, 3□.

The lead %H,,4□ has an external electrode 3. on the piezoelectric ceramic 5a at the lower end. ．． It is joined to 3□ by solder 82 and 8□.

[Problem to be solved by the invention]

In this way, in the conventional structure, the lead wires are directly soldered onto the external electrodes to join them. Therefore,
Due to the vibrations generated when pulse-driving the piezoelectric element,
The lead wire vibrates, and the bonded portion of the external electrode to the piezoelectric ceramic may peel off, making it difficult to obtain sufficient reliability.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer piezoelectric element that can improve reliability by preventing the lead wire connection portion from separating by .eta. due to drive vibration when the piezoelectric element is used.

[Means to solve the problem]

In order to achieve the above-mentioned object, in the present invention, a plurality of piezoelectric ceramics are laminated via internal electrodes to form a columnar body, and piezoelectric ceramics are formed on the circular surface of the columnar body alternately with the internal electrodes. In a laminated piezoelectric element comprising a pair of connected external electrodes, each of which is connected to a lead wire, a solder land connected to each of the external electrodes is formed on a predetermined surface of the piezoelectric ceramic. , the lead wire is connected to the solder land.

Further, a plurality of piezoelectric ceramics are laminated via internal electrodes to form a columnar body, and a pair of external electrodes are formed on the surface of the columnar body and alternately connected to each of the internal electrodes. In the laminated piezoelectric element in which each of the external electrodes is connected to a lead wire, a solder land that connects to each of the external electrodes is formed on a predetermined surface of the piezoelectric ceramic, and the lead wire is connected to the solder land. , the configuration is such that they are joined via solder.

[For production]

Since the piezoelectric ceramic and the lead wire are bonded via the solder land, the vibration of the lead wire does not affect the external electrode, which has a weak bonding force, and there is no peeling of the external electrode at the lead wire connection portion. Particularly, when the lead wires are joined onto the solder land via solder, the workability of soldering the lead wires is improved.

[Example] The present invention will be described in detail below with reference to FIGS. 1 to 4.

A first embodiment is shown in FIGS. 1 and 2.

FIG. 1 is a perspective view showing the structure of the laminated piezoelectric element 11 of this example, and in the figure, 12 is a solder land (a land portion of a solder layer).
It is. Note that the same reference numerals are used for members similar to those in the past.

The solder land 12 has external electrodes 3. ．． 3°, and the lead wires 4° and 4° are joined to the solder land 12. Figure 2 shows the solder land 12.
The details of the formation portion are illustrated for the external electrode 3I side. The solder land 12 is formed using, for example, Cerasorza manufactured by Asahi Glass and one containing Ag.

In this way, the piezoelectric ceramic 5a and each lead wire 4°,
4□ is connected via the solder land 12, so
The vibration of the lead wires 42, 4□ is caused by the external electrode 3I, which has a weak bonding force.
, 3□, and there is no peeling of the external electrode at the lead wire connection portion. Therefore, a highly reliable multilayer piezoelectric element can be obtained.

FIG. 3 shows a second embodiment.

FIG. 3 is a perspective view showing the structure of the laminated piezoelectric element 21 of this example. In the figure, 22 is a solder land, and 23 is a solder such as a cored solder.

The solder land 22 is on the surface of the piezoelectric ceramic 5a,
It is formed to be connected to the external electrodes 33, 3□, and the solder 22 is formed on the solder land 22. The lead wires 48, 4° are connected to the solder land 22 through the solder 23.
is joined to.

In the case of this example, in addition to the same effect as the previous example, there is also an effect that the workability of lead wire soldering is improved.

FIG. 4 shows a third embodiment.

FIG. 4 is an explanatory diagram of the main part structure of the laminated piezoelectric element 31 of this example, in which the external electrode 3 (and the external electrode 3°) extends a little to the piezoelectric ceramic 5a. The solder land 32 formed on the surface of the piezoelectric ceramic 5a is connected to the external electrode 3.
．． (and the external electrode 3□), and the solder 33 is formed on the solder land 32. Lead wire 41 (and lead wire 4□) is joined to solder land 32 via solder 33.

In this example as well, the same effects as in the second example can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, there is no peeling of the external electrode at the lead wire connection portion due to drive vibration when the piezoelectric element is used, and a highly reliable multilayer piezoelectric element can be obtained.

Further, by adopting a double structure in which solder is formed on the solder land and connecting the lead wire to the solder land via the solder, the workability of lead wire soldering can be improved.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the structure of a laminated piezoelectric element according to the first embodiment of the present invention, FIG. 2 is a detailed view of the main part of FIG. 1, and FIG. FIG. 4 is a perspective view showing the structure of a multilayer piezoelectric element, FIG. 4 is an explanatory diagram of the main part structure of a multilayer piezoelectric element according to the third embodiment of the present invention, and FIG. 5 is a perspective view showing the structure of a conventional multilayer piezoelectric element. In the figure, 2 is a columnar body, 30,3□ is an external electrode, 41.4□ is a lead wire, 5.5a is a piezoelectric ceramic, is an internal electrode, 1.21.31 is a laminated piezoelectric element, 2 .22.32 is solder land, 3.33 is solder.

Claims (2)

[Claims] (1) A plurality of piezoelectric ceramics are laminated via internal electrodes to form a columnar body, and a pair of external electrodes are provided on the circumferential surface of the columnar body and alternately connected to each of the internal electrodes. In the laminated piezoelectric element in which each of the external electrodes is connected to a lead wire, a solder land connected to each of the external electrodes is formed on a predetermined surface of the piezoelectric ceramic, and the lead wire is connected to the solder land. A multilayer piezoelectric element characterized by bonding. (2) A plurality of piezoelectric ceramics are laminated via internal electrodes to form a columnar body, and a pair of external electrodes are provided on the circumferential surface of the columnar body and alternately connected to each of the internal electrodes. In the laminated piezoelectric element in which each of the external electrodes is connected to a lead wire, a solder land that connects to each of the external electrodes is formed on a predetermined surface of the piezoelectric ceramic, and the lead is connected to the solder land. A laminated piezoelectric element characterized by wires bonded via solder.