JPH03155179A - Laminated displacement element - Google Patents

Abstract

PURPOSE:To improve mechanical strength of a terminal plate fully and prevent the tension from affecting an external electrode even if the tension operates on a lead member by introducing a pair of terminal plates which protrude from the side surface of a laminated body and which has an anchoring part which is formed so that it can be connected to the lead member electrically in electrically insulated state and by connecting the external electrode to the terminal plate electrically. CONSTITUTION:After a thin plate 1 with internal electrodes 2a and 2b is laminated alternately and are contact-bonded, it is fired and a laminated body 5 is formed. Then, a film 4 consisting of an insulating material and external electrodes 3a and 3b consisting of an conductive material are provided at every other layer of an end face of the internal electrodes 2a and 2b of the side surface of the laminated body 5. Each terminal plate 8a, 8b are formed in the plane contour which is nearly the same as the thin plate 1 by a conductive metal material. Then, an anchoring part 9 is allowed to protrude in one piece and is adhered to the upper and lower end faces of the laminated body 5 by an adhesive, etc. The terminal plates 8a and 8b are electrically connected to each external electrodes 3a and 3b through a solder 7, thus keeping the area between the terminal plates 8a and 8b to be electrically insulated.

Description

[Detailed description of the invention] (Industrial application field) The present invention is an actuator for an industrial robot.

This relates to electromechanical transducers used in ultrasonic motors, etc., and in particular improves laminated displacement elements that increase the amount of displacement by laminating multiple thin plates made of electromechanical transducer material via internal electrodes. It is related to.

[Conventional technology]

Conventionally, laminated displacement elements used for displacement elements used in positioning mechanisms of x-y stages, brakes, etc. are made by attaching electrodes to a thin plate made of piezoelectric ceramic material processed into a predetermined shape, and then polarizing it. 1. A method of bonding directly or via a thin metal using an organic adhesive is adopted. However, when stacking layers using adhesive as described above, depending on the usage conditions, the adhesive layer may absorb displacement due to vibration of the piezoelectric element, or the adhesive may deteriorate due to high temperature environment or long-term use. There are drawbacks.

For this reason, recently, multilayer piezoelectric elements having a multilayer chip capacitor structure have been put into practical use. That is, 1. For example, as described in Japanese Patent Publication No. 59-32040, a paste-like piezoelectric ceramic material obtained by adding a binder to raw material powder and kneading is formed into a thin plate of a predetermined thickness, and one side of this thin plate or A conductive material such as palladium is coated on both sides to form internal electrodes. A predetermined number of the above thin plates are laminated and pressed together, further processed into a predetermined shape, and then fired to form a ceramic, and external electrodes are formed on both sides of the laminate. The laminated piezoelectric element with the above structure has excellent adhesion between the thin plate made of piezoelectric ceramic material and the internal electrode, and has stable thermal properties, so it can be used satisfactorily even in high-temperature environments, and can be used for long periods of time. It has the advantage of extremely little deterioration over time.

FIG. 7 shows an example of the structure of the laminated piezoelectric element, which is so-called an alternating electrode type. In FIG. 7, a thin plate (■) is made of a piezoelectric ceramic material, and positive and negative internal electrodes 2a and 2b are alternately sandwiched and stacked to form a laminate 5. The internal electrodes 2a, 2b are each formed so that one end edge protrudes or is exposed to the outside, and are connected to external electrodes 3a, 3b each extending in the stacking direction, and a solder 7 is applied to the external electrodes 3a, 3b. The lead wire 6 is connected via.

With the above configuration, when positive and negative voltages are applied to the external electrodes 3a and 3b, an electric field is generated between the internal IIT electrodes 2a and 2b, and the thin plate 1 is elongated in the thickness direction due to the longitudinal effect of the piezoelectric ceramic material, causing displacement. arise.

Next, the one shown in FIG. 8 is an example of another laminated piezoelectric element, which is a so-called full-surface electrode type with improved piezoelectric displacement efficiency (for example, see Japanese Patent Application Laid-Open No. 196068/1983). ). In FIG. 8, the same parts are indicated by the same reference numerals as in FIG. 7, but the internal chambers Fi2a, 2b are formed so as to cover the entire surface of the thin plate 1, and the required number of sheets are laminated in the same manner as described above. Next, on one side of the laminate 5 formed as described above, coatings 4 made of an insulating material are provided on the edges of the internal electrodes 2a and 2b every other layer (for example, only on the internal electrodes 2b), and An external electrode 3a made of a conductive dielectric material is applied from above. On the other hand, on the other side of the laminate 5, a coating 4 is provided on the edge of the internal electrode (for example, 2a) not provided with the coating 4 in the same manner as described above, and an external electrode 3b is applied thereon. The effect of the above configuration is similar to that shown in FIG. 7 above.

(Problems to be Solved by the Invention) In the conventional laminated displacement element described above, the external type i3a,
3b and the lead wire 6, so-called dotting with a low melting point alloy such as solder 7 is often used. However, with this type of connection means, the connection strength of the solder 7 connection is not sufficient, so when the laminated displacement element is used in an application that generates large vibrations, such as in a vehicle, the vibration may cause the connection to be damaged. External electrodes 3a, 3b
There is a problem in that the laminated displacement element peels off from the substrate, causing malfunction of the integrated laminated displacement element. Also, the thickness of the thin plate l is, for example, 10
If it is formed to have a thickness of 0 μm, it may not be possible to secure enough space for the solder 7 to adhere, or the external electrodes i3a and 3b may be eaten away by the solder, or the coating 4 may be destroyed due to the strain suppressing effect of the solder 7, resulting in poor reliability. There is also a drawback that it reduces the Next, when applying and releasing a voltage to the laminate 5 via the lead wire 6 and the external electrodes 3a, 3b to cause the laminate 5 to expand or contract, stress acts on the external electrodes 3a, 3b. On the other hand, external electrode 3a,
The wire 3b is formed by applying or printing a silver paste, for example, and has a very thin thickness of only a few micrometers, and is easily cracked or broken due to the stress described above. If such a crack or disconnection occurs, there is a problem in that the laminate 5 cannot be expanded or contracted by a predetermined amount, resulting in malfunction of the laminate displacement element.

In order to solve the above-mentioned problems, the lead wires 6 are disposed over almost the entire length of the laminate 5 in the stacking direction, and the external electrodes 3a and 3b are electrically connected to the external electrodes 3a and 3b by, for example, solder, over almost the entire length in the stacking direction. A proposal has been made to connect them mechanically and mechanically (see Japanese Patent Laid-Open No. 63-92068).
. With such a configuration, the bonding area between the lead wire 6 and the external electric wires Fi 3a, 3b increases, so that the strength of the solder joint 9, for example, increases. Furthermore, since the joint portion extends over almost the entire length in the stacking direction, even if cracks or disconnections occur in the external electrodes 3a and 3b due to repeated expansion and contraction of the stacked body 5, all internal electrodes 2a and 2b
It is stated that there is an effect that an electrical connection state is always ensured between the lead wire 6 and the lead wire 6.

However, while the laminated displacement element having the above structure has the above effects, it also has the problem that the expansion and contraction function of the laminated body 5 is inhibited and/or cracks are generated in the laminated body 5. That is, the lead wire 6 is connected to the external electrode 3a,
If the entire length of the laminate 3b is connected by soldering or the like, the laminate 5 will be restrained by the lead wire 6, and displacement will be reduced. In addition, the external electrodes 3a and 3b, which should originally expand and contract in accordance with the expansion and contraction of the laminate 5, are made rigid, and the laminate 5 and/or the laminate 5 and the external electrode 3a are made rigid.
, 3b, which causes cranking or peeling, which impairs its function as a laminated displacement element.

Also, as shown in FIG. 9, the outermost thin plate 1a.

A laminated displacement element has also been proposed in which a conductive material 2c similar to the internal electrodes 2a and 2b is provided through and electrically connected to terminal electrodes 3c and 3d (Japanese Patent Laid-Open No. 63-1
(Refer to Publication No. 77480), according to the above proposal, there are problems when attaching the lead wires and external problems in the conventional leadless structure! There is a statement that it is possible to resolve the formation defect of the crosspiece.

However, in the above structure, it is necessary to form the conductive material 2c through the outermost thin plate 1a.
The production of the thin plate 1a becomes extremely complicated, and the conductive material 2c
There is a problem in that the reliability is low because the electrical connection between the internal electrodes 2a and 2b is unstable. Note that this type of laminated displacement element has a leadless structure, so when tension is applied to the lead wire 6 in FIGS. 7 and 8, the solder 7 and/or the external electrodes 3a, 3
There is also the problem that the anti-peeling effect of b is still insufficient.

The present invention solves the problems existing in the above-mentioned prior art, can prevent malfunctions due to cracks or disconnections in the external electrode, can sufficiently secure a predetermined displacement, and can improve the strength of the connection portion of the lead member. The present invention aims to provide a laminated displacement element.

[Means for Solving the Problems] In order to achieve the above object, first of all, in the first invention, a thin plate made of an electromechanical conversion material and an internal electrode made of a conductive material are formed to have substantially the same planar contour and contact area. In a laminated displacement element, a laminated body is formed by alternately laminating a plurality of these, and a pair of external electrodes to be connected to the internal electrodes every other layer is provided on the side surface of the laminated body.

A pair of terminal boards having a locking part that protrudes from the side surface of the laminate and is formed to be electrically connectable to the lead member are interposed in an electrically insulated state, and the external electrode and the terminal board are electrically connected. Connecting. A technical method was adopted.

Next, in the second invention, a unit laminate is formed by alternately laminating a plurality of thin plates made of an electromechanical conversion material and internal electrodes made of a conductive material, which are formed to have substantially the same planar outline and contact area. In a laminated displacement element, a plurality of layers are further laminated to form a multi-layer body, and a pair of external electrodes to be connected to the internal electrodes every other layer are provided on the side surfaces of the multi-layer body.

A pair of terminal plates having locking portions protruding from the side surfaces of the unit laminates and formed to be electrically connectable to the lead members are interposed between the unit laminates in an electrically insulated state, and
Electrically connect the external electrode and the terminal board. A technical method was adopted.

In both of the above inventions, the terminal plate can be formed of a metal material.

Alternatively, a pair of terminal plates may be formed by fixing a coating made of a conductive material to the surface of a substrate made of an insulating material in an electrically insulating state.

Furthermore, a structure may be adopted in which a divided portion made of an insulating material is provided in the intermediate portion of the terminal board.

[For production]

With the above configuration, the mechanical strength of the terminal board can be sufficiently improved, and even if tension is applied to the lead member, it can be prevented from being applied to the external electrode, resulting in accidents caused by peeling of the external electrode. It can be expected to have the effect of preventing this from occurring.

〔Example〕

FIG. 1 is a side view schematically showing an embodiment of the present invention,
Identical parts are designated by the same reference numerals as in FIGS. 7 and 8 above. In FIG. 1, first, for example, Pb (Zr, Ti)
PVB as an organic binder, BPBG as a plasticizer, and trichlene as an organic solvent are respectively added to the powder and mixed, and the mixed material is formed into a sheet-like thin plate 1 having a thickness of 1100 a by a doctor blade method. Next, a silver-palladium paste forming internal electrodes 2a, 2b is screen printed over the entire surface of this thin plate 1. For example, 100 thin plates 1 having internal electrodes 2a and 2b formed as described above are alternately stacked and pressure bonded.

Cut into a predetermined size and shape to form a laminate, 1050-1
The laminate 5 is formed by firing at 200° C. for 1 to 5 hours.

Next, on the side surface of this laminate 5, a coating 4 made of an insulating material is provided on every other layer at the edges of the internal electrodes 2a, 2b.

External electrodes 3a and 3b made of a conductive material are provided. Next, terminal plates 8a and 8b are each made of a conductive metal material such as copper or brass, and are formed to have approximately the same planar outline as the thin plate 1, and have locking portions 9 integrally projected. 5
It is fixed to the upper and lower end surfaces of the board with adhesive or other means. Note that the terminal plates 8a and 8b are electrically connected to the external electrodes 3a and 3b via solder 7, respectively. Therefore, the terminal plates 8a and 8b are maintained in an electrically insulated state.

FIG. 2(a) is a perspective view showing the terminal plates 8a and 8b in FIG. 1. In FIG. 2(a), for example, a hole 10 is provided in the locking portion 9 which is provided to protrude to the right.

With the above configuration, the lead wires are inserted into the holes 10 provided in the locking portions 9 of the terminal plates 8a and 8b, twisted and fixed as shown in FIG. The wire 6 and the terminal plates 8a, 8b can be firmly fixed. In this state, if a voltage is applied between the lead wires 6, 6, the stacked body 5 can be driven to expand and contract in the vertical direction. In this case, the terminal plate 8a.

8b can be formed to have a wall thickness of 0.05 to 3 mm, for example, and thus has high mechanical strength.

The adhesion force with the lead wire 6 is also sufficiently large. Therefore, even if unexpected tension is applied to the lead wire 6, it can be sufficiently resisted, and there is no possibility that the external electrodes 3a, 3b will peel off.

Next, FIGS. 2(b) and 2(c) are perspective views showing modified examples of the terminal plates 8a and 8b in FIG. 2(a), respectively. First, the second
In the case shown in FIG. 8(b), an insulating member 8c is fixed to one surface of terminal plates 8a and 8b. Also, Figure 2 (C
) shows an insulating member 9 also on one surface of the locking part 9.
c is fixed.

When the terminal plates 8a and 8b formed as described above are fixed to the laminate 5 shown in FIG.
Or, if it is formed so that the insulating members 8c and 9c appear,
Electrical insulation from other members adjacent to the top and bottom of the laminate 5 is provided by 61.
can be maintained.

Note that insulating members 8c and 9 are attached to the terminal plates 8a and 8b as described above.
Instead of fixing c, PZTAL, O, ZrO
A conductive member (for example, 8a in 2nd [m(C) , 8b) may be formed.

3(a) to 3(d) are plan views showing other modifications of the terminal plates 8a and 8b in FIG. 2(a), respectively.

As shown in FIGS. 3(a) and 3(b), the planar contour shape of the hole 10 provided in the locking portion 9 may be semicircular or U-shaped. Further, as shown in FIG. 3(C)(d), the locking portion 9 may be formed so as to lack the aforementioned hole.

Note that the effect is the same even if the locking part 9 is made to protrude from one side of the laminate 5 instead of from both sides as shown in FIG. As shown in FIG. 3(d), it is convenient to provide the locking portions 9 close to the corners of the terminal plates 8a, 8b.

FIGS. 4(a), 4(b), and 4(c) are perspective views showing still other modified examples of the terminal plate. Figure 4 (a) (b) (
In C), the terminal board 11 has a divided part 11c made of an insulating material in the middle part, and has a pair of terminal parts 11a,
11b in an insulated state. Note that the terminal portions 11a and 11b correspond to the terminal plates 8a8b in FIGS. 1 to 3 above.

The terminal board 11 having the above structure is fixed to either the upper or lower end surface of the laminate 5 shown in FIG. If the lead wire 6 is fixed to the terminal, it can be operated in the same manner as that shown in FIG. 1, and the same effect can be expected.

FIGS. 5(a) and 5(b) are sectional views showing modified examples of the terminal plate and the pond, respectively, and the same parts are shown in FIGS. 4(a) and 5(b).
) The one shown in FIG. 5(a), which is designated by the same reference numeral as (C), has terminal portions 11a and 11b adhered to both the front and back surfaces of a divided portion 11c made of an insulating material. Next, the fifth
The one shown in Fig. Φ) has terminal parts 11a and 11b made of a thin film of a conductive material fixed to both the front and back surfaces of one divided part 11c. Terminal parts 11a and llb made of such thin films
As a means for forming this, methods such as vapor deposition, svantalization, plating, and paste application can be applied. Note that in order to approximate the thermal expansion coefficients of the terminal portions 11a and 11b and the divided portion 11c, one divided portion 11c is made of, for example, PZT or ZrOx.
, Alz03, or other insulating material.

The effect of the above configuration is as shown in Fig. 4 (a) [Yes]) (C).
It is similar to that shown in .

FIG. 6 is a perspective view schematically showing another embodiment of the present invention, and the same parts are designated by the same reference numerals as in FIG. 1.

In FIG. 6, 5a is a multi-laminate, which is formed by laminating four laminates 5 (hereinafter referred to as unit laminates) shown in FIG. 1. Note that the terminal plates 8a and 8b are sandwiched between the unit laminates 5.5 and electrically connected to the external electrodes 3a and 3b, respectively.

With the above configuration, by applying a voltage between the lead wires 6 and 6, the multi-layer body 5a can be driven to expand and contract in the stacking direction. In this case, the terminal plate 8a8b is the unit laminate 5,
For example, the joints with the lead wires 6 can be overlaid with solder (not shown) in the same manner as shown in FIG. can be formed into a large size. Therefore, even if an unexpected tension is applied to the lead wire 6, as in the case shown in FIG. can.

In this embodiment, an example of a full-surface electrode type has been described, but it is naturally applicable to an alternating electrode type. In addition, the planar projection shape of the thin plate and the internal electrodes may be a square, a circle, an ellipse, or other geometric shapes other than a rectangle. In the above embodiment, an example was described in which screen printing was used as a means of forming the internal electrodes and external electrodes, but the method is not limited to this, and the same effect can be achieved by other methods such as plating vapor deposition or coating. be. Furthermore, in the embodiments described above, the electromechanical conversion material is a piezoelectric material.

Since the Curie temperature is lower than room temperature, there is no need for single polarization.
Also regarding electrostrictive materials which have characteristics such as large displacement and small hysteresis.

Exactly the same effect as above can be expected. Examples of such electrostrictive materials include 9.

CPbo, q+h Lao, o*a>CZro, bs
Tio, 5s) o,, tq Os + (Pbo
, ss Sro, +5) (Zro, s+ Tto, 3n
Zno,owsNi@,. 375 Nha, +11
) 03° (Pbo, ss Sro, +5) (Zro, s
o Tio, +o Zno, osNio,. 5NbO,
l. )0; etc. can be used. In addition, for the multi-layered body as shown in FIG. 6, FIG.
It goes without saying that the terminal board shown in Figure (a) can be applied.

(Effect of the invention) Since the present invention has the structure and operation as described above,
The following effects can be achieved.

(1) Sufficient space for fixing the lead member can be secured, and accidents such as solder erosion of external electrodes can be completely eliminated.

(2) Because the connection between the terminal board and the lead member is reliable, 1
Peeling of the lead member and disconnection can be avoided.

(3) Even if unexpected tension is applied to the lead member, the mechanical strength of the terminal board itself and the connection part with the lead member is sufficiently high, so there will be no accident of peeling of the external electrode. .

[Brief explanation of the drawing]

FIG. 1 is a side view schematically showing an embodiment of the present invention. FIG. 2(a) is a perspective view showing the terminal plate in FIG. 1. 2(b) and 2(C) are perspective views showing modified examples of the terminal board in FIG. 2(a), and FIG. 4(a) (bl) (C) are perspective views showing still other modified examples of the terminal board, and FIGS. 5(a) and 5(b) are plan views showing other modified examples of the terminal board. Furthermore, FIG. 6 is a cross-sectional view showing another modification, FIG. 6 is a perspective view schematically showing another embodiment of the present invention, and FIGS. 7 to 9 each schematically show an example of a conventional laminated displacement element. 3a, 3b: external electrodes, 6: lead wires, 8a, 8b, 11
: Terminal board, 9: Locking part. 7th (21 Akira O

Claims (8)

[Claims] (1) A laminate is formed by alternately stacking a plurality of thin plates made of an electromechanical transducer material and internal electrodes made of a conductive material, which are formed to have approximately the same planar contour and contact area, and the side surfaces of this laminate are In a laminated displacement element comprising a pair of external electrodes to be connected to the internal electrodes every other layer. A pair of terminal boards having a locking part that protrudes from the side surface of the laminate and is formed to be electrically connectable to the lead member are interposed in an electrically insulated state, and the external electrode and the terminal board are electrically connected. A laminated displacement element characterized by being connected. (2) Claim (1) in which the terminal plate is formed of a metal material
The laminated displacement element described above. (3) A laminated displacement element according to claim (1), wherein a pair of terminal plates are formed by fixing a coating made of a conductive material to the surface of a substrate made of an insulating material in an electrically insulating state. (4) The laminated displacement element according to claim (2), wherein a dividing portion made of an insulating material is provided in the intermediate portion of the terminal plate. (5) Further laminating a plurality of unit laminates formed by alternately laminating a plurality of thin plates made of an electromechanical conversion material and internal electrodes made of a conductive material, which are formed to have substantially the same planar outline and contact area. In a laminated displacement element formed of a multi-layered body and provided with a pair of external electrodes to be connected to the internal electrodes every other layer on the side surfaces of this multi-layered body, a portion of the unit laminated body is provided between the unit laminated bodies. A pair of terminal plates having locking portions protruding from the sides and formed so as to be electrically connectable to the lead member are interposed in an electrically insulated state, and
A laminated displacement element characterized by electrically connecting an external electrode and a terminal plate. (6) Claim (5) in which the terminal plate is formed of a metal material.
The laminated displacement element described above. (7) The laminated displacement element according to claim (5), wherein a pair of terminal plates are formed by fixing a coating made of a conductive material to the surface of a substrate made of an insulating material in an electrically insulating state. (8) The laminated displacement element according to claim (5), wherein a dividing portion made of an insulating material is provided in the intermediate portion of the terminal plate.