JPS6214483A - Manufacture of electrostrictive effect element - Google Patents

Abstract

PURPOSE:To obtain an electrostrictive-effect element having high insulation characteristics and high reliability, by forming an insulation layer by means of the electrophoresis in which an internal electrode on which the insulation layer is required to be formed is used as a negative electrode while the other internal electrode requiring no insulation film is used as a positive plate. CONSTITUTION:In order to produce an electrostrictive material layered body 6 having a layered capacitor structure, an electrostrictive material 1 and internal electrodes 2 and 3 are layered and temporary external electrodes 4 and 5 are provided on two side faces of the layers. One of the exposed side faces of the layered body 6 is covered with adhesive tape, and the layered body 6 is dipped in a suspension 11 received in a container 12 and an insulation layer is formed by means of the electrophoresis. The layered body is then cut off along cutting lines in the vicinity of the temporary external electrodes and between them to obtain a layered body having no temporary external electrodes. An external electrode 15 is then applied and baked so that the exposed ends of the internal electrodes are connected with the face of the layered body having the insulation layer. Thus, an electrostrictive-effect element is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing an electrostrictive element having a multilayer capacitor structure that utilizes the longitudinal effect.

[Conventional technology]

An electrostrictive effect element having a multilayer capacitor structure is an excellent actuator that generates large distortion at low voltage. As shown in FIGS. 12a) and b)K, this element consists of an electrostrictive material 21 and internal electrodes 22 and 23 laminated with the electrostrictive material 21 sandwiched therebetween. 23 are two external electrodes 24 and 25 provided on opposite sides.
It has a structure in which each layer is electrically connected alternately at one end of the internal electrodes 22 and 23. Therefore, the internal electrode 22 connected to one external electrode 24 and the internal electrode 26 connected to the other external electrode 25 overlap at the center, but do not overlap near the inner and outer electrodes 24 and 25.

When a voltage is applied between the external electrodes 24 and 25 of such an electrostrictive effect element, the electric field strength basically increases only in the overlapped part 26 of the positive internal electrode and the negative internal electrode, and the electrostrictive effect in that part increases. Deformation of the material occurs. Since the non-overlapping portions 27 and 28 of the internal electrodes near the external electrodes have a weak electric field strength, they not only do not deform, but also serve to inhibit deformation of the entire element.

Therefore, with an element having such a structure, it is not possible to obtain the amount of strain specific to electrostrictive materials. Also,? When a tJt pressure is applied or a voltage is applied for a long period of time, there is a problem in that the element may be destroyed due to stress concentration occurring at the boundary between the deformed part and the non-deformed part.

In order to improve the above problem, all the ends of the internal electrodes 51 are exposed to the surface of the electrostrictive material 32, and electrically connected every -m with wires 55, as shown in FIGS. 13 a) and b). It is seen that the structure is such that electrode terminals 34 and 35 are attached to the wire 33. With this structure, the internal electrodes 31 overlap only in the overlapping portion 36, so that a uniform electric field is applied to the electrostrictive material 32 when voltage is applied, and stress concentration does not occur. Therefore, a large strain inherent to the material can be obtained, and the element is less likely to be destroyed due to deformation.

However, in order to apply a high electric field to an electrostrictive material, it is necessary to set the interval between internal electrodes to about 200 μm, so it is extremely difficult from an industrial perspective to connect internal electrodes every other layer using wires. Therefore, it is conceivable to insulate the ends of the internal electrodes exposed on the side surfaces in every other layer, and then connect the internal electrodes to the external electrodes in every other layer by forming external electrodes on the entire surface of the vaginal side surface. As such a method, for example, Japanese Unexamined Patent Publication No. 5
No. 9-175176, which has a multilayer capacitor structure in which electrostrictive materials and internal electrodes are alternately laminated, and two external electrodes connecting the internal electrodes every other layer are formed on the sides. Create. Next, a DC voltage is applied between one external electrode of the laminate and an electrode plate installed separately from the laminate, and the ends of the internal electrodes on one of the exposed surfaces of the internal electrodes are electrophoresed. An insulating layer is formed every other layer in the area and its vicinity. Next, a DC voltage is applied between the other external electrode and an electrode plate installed separately from the laminate, and the exposed surface of the other internal electrode that is not yet covered with the insulating layer is detected by electrophoresis. An insulating material is formed at and near the ends of the internal electrodes. Next, cut the laminate near the external electrode, and cut every other layer to the end of the internal electrode. There is a method of forming three edge materials and forming external electrodes on a round surface.

[Problem that the invention seeks to solve]

However, in the electrophoresis method described above in which a DC voltage is applied between one external electrode of the laminate and an electrode plate installed separately from the laminate, the internal A thin layer of insulating material may adhere to the ends of the internal electrodes other than the ends of the electrodes, resulting in poor electrical continuity between the internal electrodes and the external electrodes in the electrostrictive effect element manufactured in this way. There is a problem that sometimes happens.

The present invention is intended to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing an electrostrictive element that has good insulation properties, has no electrical conduction defects between internal electrodes and external electrodes, and is highly reliable. This is the purpose.

The inner electrodes are alternately stacked, and the inner electrodes are alternately connected layer by layer to two outer electrodes provided on the sides of the laminate at one end of the inner electrodes, and the ends of the inner electrodes are connected to the outer electrodes. A step of manufacturing a laminate having a multilayer capacitor structure exposed on two side surfaces that are not provided, and exposing the two internal electrodes by an electrophoresis method in which a DC voltage is applied between the two external electrodes of the laminate. a step of forming an insulating layer every other layer at and in the vicinity of the end of the internal electrode on one of the surfaces; a step of forming an insulating layer every other layer at the end of the internal electrode and in the vicinity thereof; a step of cutting the laminate on which the laminate is formed near the cylinder external polarization, and a step of forming an external X pole so as to connect an internal electrode to the surface of the cut laminate on which the insulating layer is formed. It is characterized by

The electrostrictive material that can be used in the present invention is not particularly limited, but for example, p b Il+ =03-1'bZrU,
Pb (Mr115 Nb2/3
) (J,,Pb(Y'I/S Nb215) 0
3, Pb(Mn 115 Sb2/3 ) 03 or pb(Co115 Nb2/3 ) 03 are added. A green sheet is created using this electrostrictive material by a doctor blade method, a drawing method, or the like. An internal electrode material is formed on this green sheet by screen printing or the like, laminated, and then sintered. Platinum, palladium, or the like can be used for this internal electrode material.

An insulating layer is formed at the end of the internal electrode exposed on the side surface of the laminate by electrophoresis, and the insulating material for this insulating layer is zinc borosilicate crystalline glass powder or lead borosilicate crystalline glass powder. Can be mentioned. The thickness of the insulating layer to be formed is determined by the required withstand voltage and the insulation properties of the insulating material. For example, when insulating by depositing zinc borosilicate crystalline glass powder as an insulating layer by electrophoresis and baking it, a polarization voltage of about 500 μm is required when the thickness of the laminated electrostrictive material is about 100 μm. The withstand voltage is required to be about 1000 V, which is twice the polarization voltage, and the thickness of the deposited layer of the insulating glass powder that satisfies this withstand voltage is about 50 μm.

[For production]

Electrostrictive materials and internal electrodes are alternately laminated, and the internal electrodes are connected to two external electrodes provided on the sides of the laminated body,
Then, a laminate having a multilayer capacitor structure in which the ends of the internal electrodes are exposed on two side surfaces where no external electrodes are provided is manufactured, and a DC voltage is applied between the two external electrodes of the laminate. Since the insulating material is electrophoresed on the exposed surface of one of the internal electrodes, the charged particles of the insulating material are transferred to one of the internal electrodes connected to the two external electrodes, which has the opposite polarity to the particles. It is attracted to a part of the edge and precipitates in the vicinity of the edge. On the other end of the internal electrode, which has the same polarity as the particles, the particles are repelled because they have the same polarity, so they are not deposited at all. In this way, the internal electrodes are connected alternately to the two external electrodes, layer by layer.
Insulating layers are formed every other layer on the exposed surface of one of the internal electrodes at the ends of the internal electrodes and in the vicinity thereof.

Historically, when electrophoresis is performed by changing the surface on which the insulating layer is formed and reversing the polarity of the DC voltage applied to the two external electrodes, an insulating layer forms at the end of the internal electrode where no insulating layer is formed and in the vicinity. can be formed.

By cutting the laminate in which an insulating layer is formed at the end of every other internal electrode near both external electrodes and removing the part where the internal electrodes do not overlap, it is possible to obtain a laminate without any part where the internal electrodes do not overlap. can.

By forming external electrodes entirely on the two side surfaces of the laminate on which the insulating layers are formed, the insulating layers are alternately formed layer by layer at the ends of the internal electrodes on the two side surfaces, so that the internal electrodes can be Each layer can be alternately connected to two external electrodes. [Example] The present invention will be described by way of an example with reference to the drawings.

Example First, as shown in FIG.
We will explain the manufacturing method of a strained material laminate B with a multilayer capacitor structure in which temporary external electrodes 4.5 are laminated and temporary external electrodes 4.5 are formed on two sides.
1'ix Zr1- x ) (J3 (However, ! =
A slurry was prepared by adding a small amount of an organic binder such as polyvinyl butyral to an electrostrictive material calcined powder whose main component was 0.40 to 0.60), and dispersing this in an organic solvent such as ethanol. Next, this slurry was coated onto a polyester film to a thickness of several hundred micrometers using a casting film forming apparatus used in the production of conventional multilayer ceramic capacitors, and dried.

Next, this dried slurry was peeled off from the film to obtain an electrostrictive material green sheet. Some of the green sheets were also screen printed with platinum paste as internal electrodes. Several dozen of these green sheets were stacked, pressed into one piece using a hot press, and then fired at 1250°C. This is cut so that the internal electrodes are exposed alternately on the two opposing sides, coated with temporary external electrodes, and then cut near the sides different from the above two sides.
Laminated body 6 with exposed internal electrodes 2.5 as shown in FIG.
I got it. In FIG. 1, 7 indicates the electrostrictive material of the protective film portion, and 1 indicates the electrostrictive material that causes strain. Internal electrode 2゜5
are connected to temporary external electrodes 4 and 5, respectively.

Next, an insulating layer is formed on the electrostrictive material laminate 6 thus obtained by electrophoresis.

First, 10 t of zinc borosilicate crystal glass powder, which is an insulating material to be attached, 500 ml of ethanol, and 0 iodine.
．． 52 was mixed for 1 hour with a starter.

After mixing, the mixture was allowed to stand for 3 minutes, and the precipitate was removed to prepare a suspension. In this suspension, iodine acts as an electrolyte and the glass powder particles are positively charged.

One side of the electrostrictive material laminate 6 on which the internal electrodes 2 and 3 are exposed is covered with adhesive tape so as not to get wet with the suspension, and the temporary electrode 4 is connected to the negative terminal 8 and the other temporary electrode 5 is connected to the positive terminal. Connected to 9. Then, the negative terminal 8 and the positive terminal 9 were connected to a DC power source 10, and the laminated body 6 was submerged in a container 12 filled with the suspension 11. While the suspension 11 was stirred by the starter 13, a voltage of 20 V was applied to the outer IT poles 4 and 5 of the laminate 6. The above operation was repeated by changing the voltage application time from 10 seconds to 100 seconds.

In this way, a laminate with an insulating layer formed thereon was obtained. A cross-sectional view of the main parts of the obtained laminate is shown in FIG. The insulating layer 14 made of glass powder was formed only on the exposed end of the internal electrode 4 electrically connected to the negative terminal 8 and on the surface of the electrostrictive material in the vicinity thereof.

FIG. 4 shows a graph showing the relationship between Km pneumophoresis time and the thickness of the deposited insulating layer. When insulating by depositing an insulating glass powder layer by electrophoresis and baking it, when the thickness of the laminated electrostrictive material is about 1008°C, the polarization voltage of K is required to be about 5oov, so the withstand voltage of the insulating layer is is required to be twice as high as 1000V, and the thickness of the electrophoretic deposited layer of insulating glass required to satisfy this withstand voltage is 50 μm. Therefore, as can be seen from the graph in FIG. 4, the electrophoresis time for forming the insulating layer may be about 50 seconds or more. In this example, electrophoresis was performed for up to 100 seconds, but the exposed end of the internal electrode that should be electrically conductive was exposed to the inside 1! Since the pole was connected to the positive terminal, no insulating layer was formed and no resistance value of 0.1Ω or more was measured.

Next, on the laminate on which the insulating layer was formed by electrophoresis for 50 seconds, the surface on which the insulating layer was formed was changed, the polarity of the applied DC voltage was reversed, and the insulating layer was again formed by electrophoresis.

The laminate on which the insulating layer was formed in this way was cut along the cutting line 15 near the temporary external electrode 4.5 and between them as shown in FIG. An a-bulk without temporary external electrodes as shown in FIG. 7 was obtained.

Next, as shown in FIG. 8, the external electrode 1 is connected so that the exposed end of the internal electrode is connected to the surface on which the insulating layer of one laminate is formed.
5 was applied and baked on from a trap.

The nine electrostrictive effect elements manufactured as described above were able to apply a predetermined voltage without loss.

Comparative Example Adhesive tape was applied to the exposed surface of the internal electrode of an electrostrictive material laminate 6 having temporary external electrodes 4 and 5 obtained in the same manner as in Example, and one temporary external electrode 4 was connected to a DC power source 10. Connected the negative terminal. Next, the container 12 is filled with the suspension 11 prepared in the same manner as in Example 1, and the laminate 61 is
The stainless steel plate anode 17 connected to the DC power source 10 is placed in front 1c of the exposed surface of the internal electrode of the laminate.
It was placed at rn. 20 between the temporary external electrode 4 and the anode 17 while stirring the suspension 11 with the star 215.
Electrophoresis was performed by applying a voltage of V. ? The operation described in E was repeated by changing the time for applying pressure a from 10 seconds to 100 seconds. FIG. 10 shows a cross-sectional view of the main parts of the laminate subjected to electrophoresis for 50 seconds. An insulating layer 14 with a thickness of about 60 μm was formed on the exposed end of the pole 4 with the interior 1 electrically connected to the negative terminal 8 .

However, an insulating layer 14 with a thickness of about 6 μm was also formed at the end of the other internal electrode 5 that required conduction. FIG. 11 shows a graph showing the relationship between electrophoresis time and the thickness of the deposited insulating layer. As can be seen from this graph, when the electrophoresis time was 20 seconds or more, an insulating layer was also formed on the internal electrodes 5 which required conduction.

Next, the above operation was repeated by changing the surface on which the insulating layer was formed and replacing the temporary external electrode 4 connected to the negative terminal with the other temporary electrode 5.

The laminate thus obtained was cut in the same manner as in the examples to remove the temporary external electrodes, and external electrodes were formed in the same manner as in the examples.

Since the electrostrictive effect element obtained as described above has an insulating layer formed at the end of the internal electrode where conduction is required, a resistance of several Ω occurred when conduction was established.

Furthermore, in some cases, there is a possibility that no voltage will be applied to the element.

〔Effect of the invention〕

As described above, in the method of the present invention, the internal electrode that requires the formation of an insulating layer is used as the negative electrode, and the internal electrode that does not require the formation of an insulating layer is used as the positive electrode, and the insulating layer is formed by electrophoresis. It is possible to form an insulating layer only on the internal electrodes that require the formation of an insulating layer, without forming any insulating layer on the internal electrodes that do not require the formation of a layer. There is no need for electrical continuity with external electrodes, and a highly reliable electrostrictive effect element can be manufactured.

Furthermore, since the internal electrodes of the laminate themselves are used as both poles for electrophoresis, there is no need for counter electrodes required for normal electrophoresis, simplifying the apparatus.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an electrostrictive material laminate according to an embodiment of the present invention, FIG. 2 is a sectional view of an electrophoresis device according to an embodiment of the present invention, and FIG. 6 is an insulation diagram of an embodiment of the present invention. FIG. 4 is a graph showing the relationship between the electrophoresis time and the thickness of the precipitated insulating layer in an embodiment of the present invention, and FIG. 6 is a perspective view of a laminate cut out from the laminate shown in FIG. 5; FIG. 7 is an enlarged view of the main parts of FIG. 6; FIG. 8 is a perspective view of an electrostrictive effect element according to an embodiment of the present invention, FIG. 9 is a cross-sectional view of an electrophoretic device according to a comparative example, and FIG. 10 is an electrostrictive material laminate with an insulating layer formed as a comparative example. Figure 11 is a graph showing the relationship between the electrophoresis time and the thickness of the precipitated insulating layer in a comparative example; @Figure 12 a] is a side view of a conventional multilayer capacitor type electrostrictive element; Figure 12 b) is a top view of Fig. 12q), Fig. 16a
) shows a side view of the conventional laminated electrostrictive element, and FIG. 13b) shows a top view of FIG. 13a). In the figure, 1.7, 21.32... Electrostrictive material 2.5, 22, 25.5'I... Internal electrode 4.5...
-Temporary external electrode 6...Laminated body 8...Minus terminal 9...Positive terminal 10...DC IT source
11... Suspension 12... Container 15 River stirrer 14... Insulating layer 16.24.25... External electrode 17... Anode 33... Wire patent Applicant Toyota Motor Corporation ( and 1 other person) Figure 8 Figure 9 Figure 10 □ C) C) Ω -q Folded earth insulation layer thickness 2 μm

Claims (1)

[Claims] Electrostrictive materials and internal electrodes are alternately laminated, the internal electrodes are alternately connected layer by layer at one end of the internal electrodes to two external electrodes provided on the side surfaces of the laminate, and manufacturing a laminate having a multilayer capacitor structure in which the ends of the internal electrodes are exposed on two side surfaces where no external electrodes are provided; and applying a DC voltage between the two external electrodes of the laminate. forming an insulating layer every other layer at the end of the internal electrode and its vicinity on one of the two exposed surfaces of the internal electrode by electrophoresis, and reversing the polarity of the applied DC voltage. ,
A step of changing the exposed surface of the internal electrode forming the insulating layer to the other surface and forming an insulating layer every other layer at the end of the internal electrode and its vicinity in the same manner as described above; An electrostrictive effect element comprising the steps of cutting near the external electrode, and forming the external electrode on the surface of the cut laminate on which the insulating layer is formed so as to connect the external electrode to the internal electrode. Production method.