JPH0766468A - Method for manufacturing integrally fired laminated piezoelectric material - Google Patents

Abstract

(57) [Summary] [Structure] A plate-shaped molded body that becomes a piezoelectric ceramic by firing and an electrode material that becomes an internal electrode by firing are alternately laminated and integrated, and then this is fired and processed, and then the internal A raw material powder for producing a piezoelectric ceramic containing 0 to 5% by weight of an organic molding aid in a method for producing an integrally fired laminated piezoelectric material by performing insulation treatment of electrodes, connection of connecting electrodes, and connection of lead wires. An integrally fired laminated piezoelectric material characterized by laminating an electrode material having adhesiveness with a molded body formed by molding a sheet into a plate, or laminating an electrode material on the molded body via an adhesive layer. Body manufacturing method. [Effect] Since a large laminated piezoelectric ceramic can be produced with high yield and high mass productivity, it is possible to inexpensively and reliably manufacture a piezoelectric actuator as a mechanical component that requires a large generative force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integral firing type laminated piezoelectric body, particularly a large-sized laminated piezoelectric body, which is obtained by alternately laminating a plate-shaped molded body which becomes a piezoelectric ceramic by firing and an internal electrode material and then firing. The present invention relates to a method for manufacturing a large-sized laminated piezoelectric material having a generating force.

[0002]

2. Description of the Related Art An integrally fired laminated piezoelectric material is usually manufactured by a method similar to the method used in manufacturing a so-called laminated capacitor. Generally, first, a sheet-shaped molded body is manufactured by a doctor blade method or the like. For example,
A raw material powder of lead zirconate titanate (hereinafter abbreviated as PZT), which is a raw material of the piezoelectric ceramic, is used as an organic molding aid such as an organic binder, a plasticizer, and a dispersant.
A sheet-shaped molded product (green sheet) that is mixed with wt% and a solvent, cast on an organic film to a certain thickness, dried to remove the solvent, and then peeled off from the organic film.
To manufacture.

Then, a paste-like electrode material, which is an internal electrode made of Ag-Pd, for example, is printed on the obtained green sheet in a predetermined pattern, dried and cut into a desired size, and a plurality of sheets are laminated. Then, they are integrated by a heat press. At this time, the organic binder and the plasticizer in the green sheet react with each other by heating to develop adhesiveness, and further, the internal electrode layer and the green sheet layer are adhered to each other by applying pressure, whereby integration is performed. After this 1000-125
By firing at a temperature of 0 ° C., a laminated piezoelectric material in which internal electrode layers and piezoelectric ceramic layers are alternately laminated is obtained.

As the metal powder used for the paste-like electrode material for the internal electrode, Pt, Pd, Ag-Pd, etc. are prized because they have good heat resistance and do not react with the raw material powder of the piezoelectric ceramic. Has been done. As another method for manufacturing the integrally fired laminated piezoelectric material, a raw material powder of the piezoelectric ceramic is formed into a single sheet in advance, fired and processed to prepare a piezoelectric ceramic plate, and then the piezoelectric ceramic plate A method called a stacking method, in which a plurality of electrodes are formed and then laminated, or a plurality of piezoelectric ceramic plates and electrode materials are alternately laminated, is also commonly used.

For example, in Japanese Patent Laid-Open No. 63-65688, a raw material powder for piezoelectric ceramics is formed into a plate shape in advance and fired to form a piezoelectric ceramic plate, which is subjected to processing such as double-side polishing. Ag by screen printing
There is disclosed a method in which an electrode paste such as the above is applied and fired to form an electrode, the obtained piezoelectric ceramic plate is polarized, and then laminated with an insulating adhesive to obtain a laminated body. Further, Japanese Patent Laid-Open No. 59-135784 discloses a method of bonding together with a metal foil used as a take-out electrode, for example, a stainless steel foil having a thickness of 30 μm, without using an adhesive, and Japanese Laid-Open Patent Publication No. 2-114683 discloses a method for bonding electrodes. Various methods such as a method of applying a paste-like electrode material to be an internal electrode to an unattached piezoelectric ceramic plate, bonding the paste before the paste has dried, and then firing to obtain a laminate are disclosed. There is.

As a method for molding the raw material powder of the piezoelectric ceramic into a single sheet, a green sheet formed into a sheet by a doctor blade method or the like is punched into a predetermined size, or a die press molding method or the like is used. it can. The obtained molded body is usually 1100 to 1300 ° C.
The piezoelectric ceramic plate can be manufactured by firing at a certain degree and performing mechanical processing such as double-side polishing.

The laminated body obtained by alternately laminating the piezoelectric ceramic layers and the internal electrode layers obtained as described above is such that the internal electrodes are positive electrodes and negative electrodes every other layer, that is, each piezoelectric ceramic layer. Insulation treatment and external electrode connection treatment are performed so that the layers are electrically connected in parallel, and polarization treatment is further performed to obtain a laminated piezoelectric body. As a method of insulating or connecting each internal electrode every other layer, usually, the internal electrodes exposed on the side surface of the laminate are coated with an insulator every other layer by, for example, a screen printing method, and the remaining internal electrodes are provided every other layer. A method of forming a conductive paste by screen printing is used to connect the layers. Also,
The polarization treatment is performed, for example, in an insulating oil at 70 to 100 ° C.
It is carried out by applying a DC voltage at 103 kv / mm for 5 to 15 minutes.

[0008]

When a monolithic laminated piezoelectric material is manufactured as described above, it is usually formed into a sheet by a doctor blade method or an extrusion method. Contains 10 to 20% by weight of an organic molding aid such as an organic binder and a plasticizer. For this reason, degreasing is difficult, and if it is long, it takes dozens of days, and the degreasing process is very long.In addition, when manufacturing a large laminated piezoelectric body that can generate large power, There was a big problem that the production yield was lowered due to cracks in the resin and the incomplete removal of the organic binder. Therefore, according to the conventional method, the size of the laminated piezoelectric material that can be manufactured with a good yield without causing such a problem is 10 × 1 in the cross-sectional area in the direction perpendicular to the laminating direction.
The limit was about 0 mm, and the length in the stacking direction was about 20 to 25 mm.

On the other hand, although the stacking method can manufacture a large-sized laminated piezoelectric material, since a large-sized single-piece piezoelectric ceramic plate is manufactured in advance and then laminated, the deformation caused during firing of the piezoelectric ceramic plate is prevented. Mechanical processing such as double-side polishing of the piezoelectric ceramic plate for improving so-called dimensional accuracy in order to improve the parallelism and flatness or to make the thickness of each piezoelectric ceramic plate to a predetermined thickness. However, there are major problems such as lack of mass productivity and increased cost.

[0010]

DISCLOSURE OF THE INVENTION As a result of intensive studies to solve the above problems, the present inventors have found that a binder or a plasticizer in a plate-shaped molded body which becomes a piezoelectric ceramic by firing. The content of the organic molding aid such as is 0 to 5% by weight, the plate-shaped molded body and the internal electrode material having adhesiveness are alternately laminated and integrated, and then baked to obtain the above-mentioned material. The inventors have found that the problems can be solved and arrived at the present invention.

That is, the gist of the present invention is to alternately laminate a plate-shaped molded body, which becomes a piezoelectric ceramic by firing, and an electrode material, which becomes an internal electrode by firing, for integration, and then fire the laminated body. In the method for producing an integrally fired laminated piezoelectric material by processing, processing, insulating treatment of internal electrodes, connection of connecting electrodes, and connection of lead wires, an organic molding aid is added to
A raw material powder for producing a piezoelectric ceramic containing 5% by weight is formed into a plate shape, and then the formed body and an internal electrode material having adhesiveness are alternately laminated and integrated, and then fired. The method of manufacturing an integrally fired laminated piezoelectric material described above.

The present invention will be described in detail below. In the present invention, the organic molding aid means a binder, a plasticizer, a dispersant, a release agent and the like. The raw material powder of the piezoelectric ceramic is not particularly limited as long as it becomes a piezoelectric ceramic by firing. As a method for forming a raw material powder for producing a piezoelectric ceramic containing 0 to 5% by weight of an organic forming aid into a plate shape, a die pressing method capable of easily forming the raw material powder into a plate shape is used. Although preferable, it is not particularly limited as long as it is a method capable of stably obtaining a plate-shaped molded body.

In the present invention, the content of the organic molding aid in the raw material powder for producing the piezoelectric ceramic is 0 to 5% by weight, preferably 0 to 3% by weight. The content of the organic molding aid is preferably as small as possible, and if it exceeds 5% by weight, degreasing becomes very difficult, which is not preferable. When molding into a plate shape by the die pressing method, add 0% of organic molding aid.
A slurry prepared by mixing raw material powder for producing a piezoelectric ceramic containing 5 to 5% by weight with water is granulated using a spray dryer or the like and used as a raw material. The obtained granular raw material is filled in a crown shape, and usually 500 to 2000 kgf / cm ²
Uniaxial press molding is performed with the molding pressure of.

However, such a low-binder amount molded body is usually laminated and integrated because the molded body has a small adhesiveness even when pressure and heat are applied when laminating and integrating. Is difficult. In the present invention, in order to laminate and integrate a predetermined number of electrode materials each of which serves as an internal electrode by firing with the molded body, the electrode material serving as an internal electrode is used as an adhesive agent for integration. That is, the present invention is characterized by using an internal electrode material having adhesiveness as the internal electrode material. Adhesiveness in this case is sufficient strength when handling the laminate before firing. Anything can be used.

As a method of laminating and integrating, for example, an electrode paste obtained by kneading a metal powder to be an internal electrode after firing, a binder, a plasticizer, a dispersant, a solvent and the like is molded as described above. It is applied on a plate-shaped molded body that becomes a piezoelectric ceramic by firing, and a predetermined number of layers are stacked before the paste dries, that is, before it dries and hardens, and the solvent in the electrode paste is pressed and heated. It is possible to obtain a dry integrated laminate by removing volatile components such as.
Examples of the method of applying the electrode paste onto the plate-shaped molded body include a screen printing method, a brush coating method, and a spray atomizing method.

As the metal powder used for the paste-like electrode material to be the internal electrode, Pt, Pd, Ag-Pd, etc. are preferable. In addition, an electrode sheet having adhesiveness that is formed into a sheet shape in advance is prepared, and the plate-shaped formed body that becomes the piezoelectric ceramic by firing and the electrode sheet are alternately laminated, and then pressurized and heated. A dry, integrated laminate can be obtained. In this case, as the electrode sheet having adhesiveness, there may be used an electrode sheet which itself does not have adhesiveness at room temperature, but exhibits adhesiveness by heating, or an electrode sheet having an adhesive layer formed on one side or both sides. Further, it is also possible to use a plate-shaped molded body that becomes a piezoelectric ceramic by firing and has an adhesive layer formed on one side or both sides.

As a method for producing an electrode sheet, for example, a metal powder for an electrode material to be an internal electrode, a binder,
A plasticizer, a dispersant and a solvent are kneaded into a slurry,
After that, 1 on the organic film by the doctor blade method, etc.
Examples include a method of molding to a thickness of 0 to 30 μm, drying, peeling from the organic film, and punching into a predetermined shape. Also,
A release layer is formed on an organic film that serves as a base film, and a metal powder for an electrode material that serves as an internal electrode is formed thereon,
A paste-like mixture obtained by kneading a binder, a plasticizer, a dispersant, a solvent, etc. is printed and applied in a predetermined pattern by a screen printing method or the like to form a transfer material, which is then heated, laser, water or the like from the base film. A peeling method can also be used. When this transfer method is used, the composition of the material is changed when it is formed on the base film, and the transfer material is formed so as to be peeling layer / adhesive layer / electrode material layer / adhesive layer, and adhered to the transfer material itself. It may have a product.

As the metal powder used for the electrode sheet to be the internal electrode, Pt, Pd, Ag-Pd and the like are preferable as in the case of the pasty electrode material. Further, as a binder used for the electrode sheet, when the electrode sheet itself is to have adhesiveness, an appropriate amount of a plasticizer is added to the thermoplastic resin so that it does not have adhesiveness at room temperature, but softens with heating. What develops adhesiveness is preferable. For example, a butyral resin or an acrylic acid-based resin can be used as the thermoplastic resin, and a phthalate ester-based resin or the like can be used as the plasticizer.

It is preferable that the content of the organic component such as the binder contained in the paste-like electrode material and the electrode sheet is as small as the content of the organic component in the piezoelectric ceramic, but in the laminate before firing. The thickness of the internal electrode is usually about 10
Since it is as thin as about μm and can be easily degreased during firing, it has little influence on degreasing failure and is not particularly limited.

[0020]

[Function] By making the content of the organic component such as the binder in the piezoelectric ceramics extremely small, degreasing becomes easy and not only the degreasing process can be shortened significantly, but also
It becomes possible to manufacture a large-sized laminated piezoelectric material with a good yield. In addition, mechanical processing such as double-sided polishing of single-wafers, which is required in the stacking method, is not required, resulting in effects such as excellent mass productivity and reduction in manufacturing cost.

[0021]

EXAMPLES The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Example 1 As a piezoelectric raw material powder, a complex oxide powder having a PZT diameter (average particle diameter 0.8 μm) was used, and as a binder, polyvinyl alcohol (hereinafter referred to as “polyvinyl alcohol”) was added so that the weight ratio after drying was 0.8% by weight. PVA), 0.2% by weight of dispersant and 0.2% by weight of release agent, that is, 1.2% by weight of the total amount of organic molding aids.
These raw material powders were dispersed in water as a dispersion medium using a ball mill, and the resulting slurry was used to prepare granules having an average particle size of about 50 μm using a spray dryer.
The obtained granules are filled in a metal mold having a diameter of 20 mm,
Uniaxial pressure molding was carried out at a molding pressure of 2 t / cm ² to obtain a thickness of 0.
A plurality of two types of plate-shaped molded bodies having a size of 6 mm and a thickness of 2.4 mm were manufactured.

Next, as shown in FIG. 2, a Pt powder and an organic bond were formed on one surface of each of the obtained molded body 8 having a thickness of 0.6 mm and the molded body 8 ′ having a thickness of 2.4 mm by a screen printing method. A Pt paste (ML-3822 made by Shoei Kagaku Co., Ltd.) composed of an agent and a solvent is applied, and before the Pt paste is dried, a molded body 8'having a thickness of 2.4 mm is used as the first layer from the second layer. Molded body 8 having a thickness of 0.6 mm up to the 59th layer, molded body 8 ′ having a thickness of 2.4 mm for the 60th layer
(Pt paste was not applied to the 60th layer molded body 8 ′) was sequentially laminated to obtain a laminated body. P used here
The t paste has adhesiveness before being dried, but if it is dried, the adhesiveness becomes small. Therefore, it is necessary to stack the Pt paste before it is dried.

Further, the obtained laminated body is inserted into a mold having an inner diameter substantially the same as the outer diameter of the laminated body, and a pressure of about 200 kg / cm ² is applied in the laminating direction at 150 ° C.
Was heated and dried for 15 minutes to remove the solvent in the Pt paste, and the layers were integrated. The resulting integrated laminate is 6
After the temperature was raised to 00 ° C. at 1 ° C./min and held for 4 hours, the temperature was further raised to 1240 ° C. at 10 ° C./min and held for 84 hours to obtain a laminated sintered body. The obtained laminated sintered body is
A piezoelectric ceramic layer having a thickness of 2 mm is provided on the upper and lower sides, and a piezoelectric ceramic layer having a thickness of 0.5 mm and Pt layers having a thickness of 0.005 to 0.01 mm, which are internal electrodes, are alternately stacked in the center. There is.

The outer circumference of the obtained laminated sintered body was adjusted to 16 mm by using a centerless grinder, and the internal electrodes were exposed on the side surfaces. In order to connect the internal electrodes to each other in parallel, as shown in FIG. 1, an insulating glass paste is applied by screen printing to a part of the exposed end faces of the odd-numbered internal electrode layers 1, and then, Insulating glass paste is applied by screen printing to a part of the exposed end surface of the even-numbered internal electrode layers 1 ', and the temperature is 800 ° C after drying.
It was baked for 15 minutes to form an insulating layer 2. Next, in order to connect the odd-numbered internal electrodes and the even-numbered internal electrode layers, an Ag paste was similarly applied by screen printing as the connecting electrodes 4, dried, and baked at 600 ° C. for 15 minutes. Furthermore, after soldering the lead wires 6,
A direct current voltage of 1000 V was applied at 5 ° C. for 5 minutes to carry out polarization treatment to obtain a laminated piezoelectric material 5.

Example 2 Using the same plate-shaped molded bodies 8 and 8'as used in Example 1, internal electrodes were formed as follows and laminated and integrated. First, Pt powder (particle size 2 to 5 μm) 16 as a raw material
5.7 g (94.0% by weight), polyvinyl butyral resin as an organic binder (Sekisui Chemical Co., Ltd. BL-
1) 4.8 g (2.7% by weight), 4.2 g (2.4% by weight) of dibutylphthalic acid as a plasticizer and 1.7 of a dispersant.
g (1.0% by weight) and ethyl cellosolve 1 as a solvent
6.7 g of each was weighed, mixed and dispersed by a ball mill to obtain an electrode slurry. Then, the obtained electrode slurry was applied onto a polyethylene terephthalate (PET) film by a doctor blade method to give a dry thickness of about 20 μm.
It was coated so as to have a thickness of m, dried and then peeled from the PET film to form a sheet. Further, it was punched into a size of 20 mm in diameter to obtain a sheet for internal electrodes.

Then, as shown in FIG. 3, the obtained internal electrode sheet 9 and the plate-shaped molded bodies 8 and 8'similar to those used in Example 1 are alternately laminated to form a laminated body. Obtained. The obtained laminated body was inserted into a mold having an inner diameter approximately the same as the outer diameter of the laminated body, and heated at 150 ° C. for 15 minutes while being pressurized with a load of about 200 kg / cm ² in the laminating direction. Layered and integrated. Further, in the same manner as in Example 1, firing, processing, insulation treatment of internal electrodes, connection of connecting electrodes, and soldering of lead wires were performed to obtain a laminated piezoelectric material.

Example 3 Using the same plate-shaped moldings 8 and 8'as used in Example 1, internal electrodes were formed as follows. First, FIG.
As shown in the above, the second embodiment was applied onto the slide paper 10 for transfer printing, which was coated with the water-soluble adhesive as the release layer 11.
20m in diameter using the same electrode slurry as used in
A plurality of screens having a size of m were screen-printed and dried to obtain a transfer sheet 13 on which the internal electrode sheet 12 was formed. Then, the obtained transfer sheet is moistened with water and peeled off from the slide paper 10 which is a mount to peel off the internal electrode sheet 12.
Got The obtained sheet 12 for internal electrodes was attached to one surface of a plate-shaped molded body 8 or 8 ′ similar to that used in Example 1. Hereinafter, in the same manner as in Example 1, lamination, integration, firing,
Processing, insulation treatment of internal electrodes, connection of connecting electrodes, and soldering of lead wires were performed to obtain a laminated piezoelectric material.

Example 4 Using the same plate-shaped moldings 8 and 8'as used in Example 1, internal electrodes were formed as follows. First, FIG.
As shown in FIG. 5, a wax having a melting point of 60 to 70 ° C. is applied to the release layer 15 to a thickness of about 1 μm and a P thickness of 10 μm is applied.
The ET film was used as the base film 14, and the same electrode slurry as that used in Example 3 was used thereon, and the diameter of 2
A thermal transfer sheet 1 having a sheet 16 for internal electrodes formed by screen-printing a plurality of sheets in a size of 0 mm and drying.
Got 7.

The obtained thermal transfer sheet 17 was overlaid on the same plate-shaped molded body as used in Example 1 to perform thermal transfer,
The sheet 16 for internal electrodes was transferred and formed on one surface of the plate-shaped molded body. Thereafter, in the same manner as in Example 1, lamination, integration, firing, processing, insulation treatment of internal electrodes, connection of connecting electrodes, and soldering of lead wires were performed to obtain a laminated piezoelectric body.

[0031]

According to the present invention, a large laminated piezoelectric body can be produced with a good yield and mass productivity, so that a piezoelectric actuator as a mechanical component requiring a large force can be manufactured inexpensively and reliably. Can be done and is very useful industrially.

[Brief description of drawings]

FIG. 1 is a schematic view showing the structure of a laminated piezoelectric body.

FIG. 2 is a schematic diagram showing a stacking and integrating method of Example 1.

FIG. 3 is a schematic diagram showing a stacking and integrating method according to a second embodiment.

FIG. 4 is a schematic diagram showing a transfer sheet of Example 3.

FIG. 5 is a schematic diagram showing a thermal transfer sheet of Example 4.

[Explanation of symbols]

 1, 1'Internal electrode layer 2 Insulating layer 3 Piezoelectric ceramic layer 4 Contact electrode 5 Laminated piezoelectric body 6 Lead wire 7 Electrode paste 8,8 'Plate-shaped molded body 9 Sheet for internal electrode 10 Slide paper for transfer printing 11 , 15 Release layer 12, 16 Internal electrode sheet 13 Transfer sheet 14 Base film 17 Thermal transfer sheet

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[Procedure amendment]

[Submission date] August 25, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

That is, the gist of the present invention is that a plate-shaped molded body which becomes a piezoelectric ceramic by firing and an electrode material which becomes an internal electrode by firing are alternately laminated and integrated, and then fired and processed. In the method for producing an integrally fired laminated piezoelectric material by performing insulation treatment of internal electrodes, connection of connecting electrodes, and connection of lead wires, an organic molding aid is added to
5% by weight of the raw material powder for producing a piezoelectric ceramic is molded into a plate, and an electrode material having adhesiveness with this is laminated, or the electrode material is bonded to the molded body via an adhesive layer. And a method for manufacturing an integrally fired laminated piezoelectric material, which is characterized by laminating.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Aihara 1060 Narita, Odawara, Kanagawa Kasei Optonix Co., Ltd.

Claims (5)

[Claims] 1. A plate-shaped molded body that becomes a piezoelectric ceramic by firing and an electrode material that becomes an internal electrode by firing are alternately laminated to be integrated, and then the laminated body is fired, processed, and In a method for producing an integrally fired laminated piezoelectric material by insulation treatment, connection of connecting electrodes, and connection of lead wires, a raw material powder for producing a piezoelectric ceramic containing 0 to 5% by weight of an organic molding aid is produced. A method for producing an integrally fired laminated piezoelectric material, which comprises: forming into a shape, and then alternately laminating the formed body and an internal electrode material having adhesiveness to perform integration, and then firing. 2. A monolithic laminated piezoelectric body according to claim 1, wherein a plate-shaped molded body obtained by press molding a powder for producing a piezoelectric ceramic containing 0 to 5% by weight of an organic molding aid is used. Law. 3. A plate-like material obtained by applying a paste-like electrode material, which becomes an internal electrode by firing, to a plate-like molded body, and applying the paste-like electrode material before the paste-like electrode material is dried and cured. The method for producing an integrally fired laminated piezoelectric body according to claim 1, wherein a plurality of the molded bodies of (1) are laminated and dried under pressure. 4. The method for producing an integrally fired laminated piezoelectric material according to claim 1, wherein an electrode material which has been formed into a sheet in advance is used as an electrode material which becomes an internal electrode by firing. 5. The method for producing an integrally fired laminated piezoelectric material according to claim 1, wherein an electrode material which becomes an internal electrode by firing is formed on one surface of a plate-shaped molded body by a transfer method.