JP2006303349A - Method for manufacturing piezoelectric ceramic lamination element and piezoelectric ceramic lamination actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a piezoelectric ceramic lamination element and a piezoelectric ceramic lamination actuator, wherein a thin layer of a piezoelectric ceramic can be accomplished for low voltage driving, and a low-cost base metal internal electrode can be used. <P>SOLUTION: A laminated body is formed by laminating piezoelectric ceramics 11 and internal electrodes 12 alternately, and a ceramic insulator 14 is provided on a side face of this laminated body for insulating ends of the internal electrodes 12 every layer so as to constitute an opposing electrode. An external electrode 15 is connected to the internal electrode 12 which remains exposed to the side face, and the ceramic insulator 14 is formed through a resist coating and exposure process to the side face by an aerosol deposition method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a piezoelectric ceramic multilayer element and a piezoelectric ceramic multilayer actuator, and is used for, for example, a precision positioning device such as an optical device used for automobile injection and semiconductor manufacturing equipment, and a valve driving element of a mass flow controller. The present invention relates to a piezoelectric ceramic laminated actuator, and in recent years, a piezoelectric microactuator used for a micro robot, a small portable device, or the like.

  Conventionally, as a piezoelectric ceramic multilayer element, a piezoelectric ceramic multilayer actuator in which piezoelectric ceramics and internal electrodes are alternately laminated is known. 3A is a perspective view of a conventional piezoelectric ceramic multilayer actuator element, FIG. 3B is a longitudinal sectional view taken along the line B-B, and FIG. 3C is a view showing a joint between an internal electrode and an external electrode. It is a schematic cross section which expands and shows. In this actuator, the piezoelectric ceramics 11 and the internal electrodes 12 are alternately laminated to form a laminated body 13, which is insulated with glass so as to form a counter electrode structure every other layer on both side surfaces with respect to the lamination direction. The insulating glass 24 is configured such that glass particles charged in water are electrophoresed to an end face electrode having a charge opposite to that of glass, and selectively adhered to every other layer, and then baked in the atmosphere. To form. An external electrode 15 is formed on the side surface of the element insulated by glass, and a lead wire 16 is further fixed by solder 17 on the external electrode.

  By the way, in recent years, the miniaturization, low profile, and low voltage of devices have progressed, and the demand for miniaturization, low profile, and low voltage drive has been remarkably increased also in the piezoelectric ceramic laminated actuator. In order to drive at a low voltage, it is necessary to shorten the distance between the electrodes in order to obtain the electric field strength necessary for driving. That is, it is necessary to reduce the thickness of the piezoelectric ceramic.

  In the prior art, for example, Patent Document 1 proposes to make the particle size of glass used in the glass migration process when forming glass insulation fine, but the distance between the electrodes is limited to 100 μm at the maximum. It is. However, in order to meet the recent demands for downsizing and low-voltage driving of devices, it is necessary to further reduce the thickness.

JP 60-86881 A

  Thus, in order to drive the piezoelectric ceramic multilayer actuator at a low voltage, it is necessary to reduce the ceramic thickness in order to increase the electric field strength. In the above conventional actuator manufacturing method, the glass baked when forming the glass insulation spreads, making it difficult to insulate every other layer. Therefore, there is a limit to thinning the ceramic layer in the conventional manufacturing method. Therefore, there is a limit to low voltage driving, and improvement of the manufacturing method is required.

  Further, expensive palladium is used as the internal electrode material, and there is a problem that the amount of palladium to be used increases with the recent thinning of the piezoelectric ceramic and the increase in the number of laminated layers, and the manufacturing cost increases. For this reason, attempts have been made to use a base metal for the internal electrode. However, since the glass insulation is baked in the air, the internal electrode is oxidized and the resistance of the electrode is increased.

  That is, an object of the present invention is to provide a method of manufacturing a piezoelectric ceramic multilayer element and a piezoelectric ceramic multilayer actuator that can be driven thinly and can use an inexpensive base metal internal electrode because displacement driving is performed at a low voltage. There is.

  In the method for manufacturing a piezoelectric ceramic multilayer element according to the present invention, piezoelectric ceramic layers and internal electrode layers are alternately stacked, the end portions of the internal electrode layers are exposed on the outer side surface of the laminate, and the end portions are formed every other layer. In the method of manufacturing a piezoelectric ceramic multilayer element having a plurality of ceramic insulators to be insulated and having external electrodes for connecting the non-insulated ends, the step of forming the ceramic insulator includes the end portions of the internal electrode layers. A step of forming a resist layer by coating a photosensitive resist or applying a dry sheet resist to the entire outer surface of the exposed external side surface, and the resist so that every other end of the internal electrode layer is masked. An insulating ceramic film is formed by an aerosol deposition method on the outer side surface where the internal electrode layer is exposed every other layer, in which a layer is exposed to light and partly removed with a developer. And having degree and, a step of peeling all the remaining resist layer.

The insulating ceramic layer is composed of a ceramic mainly composed of lead zirconate titanate (Pb (Zr, Ti) O ₃ ), alumina (Al ₂ O ₃ ), zirconia oxide (ZrO ₂ ), and barium titanate (BaTiO ₃ ). It is good to consist of either.

  In addition, the piezoelectric ceramic multilayer actuator of the present invention is formed using a piezoelectric ceramic multilayer element obtained by the method for manufacturing a piezoelectric ceramic multilayer element.

  Conventionally, since insulation between different electrodes was made by glass electrophoresis by electrophoresis and baking, it was difficult to produce a thickness of 100 μm or less when the thinning of the ceramic was promoted. Then, insulation is possible up to 15 μm.

  Further, according to the present invention, since there is no baking step in the air when forming the glass insulation, the internal electrode can be formed using not only a conventional Ag / Pd material but also an inexpensive base metal, and an inexpensive piezoelectric ceramic multilayer element. Can be provided. Further, when Ag is not used as the internal electrode material, it is possible to prevent the deterioration of insulation due to migration. Furthermore, conventionally, it has been necessary to take into consideration the penetration and wettability of the ceramic during glass baking. However, since the present invention can form a ceramic at room temperature, it also has the effect of suppressing quality variations.

  The above-mentioned aerosol deposition method is a ceramic film-forming method in which aerosolized fine powder collides and solidifies at a subsonic speed with a gas through a nozzle on a work set in a vacuum chamber. It has the feature that can be formed.

At that time, the ceramic material for insulation may be a ceramic mainly composed of lead zirconate titanate Pb (Zr, Ti) O ₃ that can be formed by an aerosol deposition method, or alumina Al ₂ O ₃ , zirconia oxide ZrO. _2. Insulating ceramics such as barium titanate BaTiO ₃ may be used.

  According to the method for manufacturing a laminated piezoelectric ceramic element of the present invention, the piezoelectric ceramic layer can be made thin even when the internal electrode has a full-surface electrode structure as in the prior art, and low voltage driving is possible. In addition, by using a reduction-resistant material for the piezoelectric ceramic, it is possible to use a base metal material for the internal electrodes, and the manufacturing cost can be reduced. Furthermore, it is possible not to use Ag as the electrode material, and it is possible to provide a piezoelectric ceramic laminated actuator excellent in reliability in which migration is unlikely to occur.

  FIG. 1 shows a piezoelectric ceramic multilayer element according to an embodiment of the present invention. FIG. 1 (a) is a perspective view, and FIG. 1 (b) is a longitudinal section along the line AA in FIG. 1 (a). FIG. 1C is a schematic cross-sectional view showing an enlarged joint portion between the internal electrode and the external electrode.

  As shown in FIG. 1, the piezoelectric ceramic multilayer element is formed of ceramics with the end portions of the internal electrodes 12 disposed on the side surfaces of a laminate formed by alternately laminating a plurality of piezoelectric ceramics 11 and internal electrodes 12 having the same area. An external electrode 15 composed of a conductive material mainly composed of silver and glass frit is bonded to the end portion of the internal electrode 12 which is covered with the insulator 14 and is not covered with the insulator, and the lead wire 16 is soldered to the external electrode 15 with the solder 17. The connection is fixed and configured.

The piezoelectric ceramic is made of a piezoelectric ceramic material mainly composed of lead zirconate titanate Pb (Zr, Ti) O ₃ (PZT). This piezoelectric ceramic desirably has a high piezoelectric strain constant d ₃₃ indicating its piezoelectric characteristics. An internal electrode 12 is laminated between the piezoelectric ceramics 11. The internal electrode 12 may be formed of a base metal in addition to Ag / Pd, which is a noble metal, if the piezoelectric ceramic 11 is given reduction resistance. Is possible. As the base metal, there are Cu, Ni, Cu / Ni alloys, etc., and Cu is particularly desirable because it is not easily oxidized during firing. In the conventional method, glass is used for insulation between different electrodes, but in the present invention, an insulating ceramic is used. The insulation formation by the ceramic of the present invention is performed by an aerosol deposition method.

  A predetermined voltage is applied to each piezoelectric ceramic 11 to cause the piezoelectric ceramic 11 to be displaced by an inverse piezoelectric effect. Conventionally, the thickness of the piezoelectric ceramic, that is, the distance between the internal electrodes has been 250 to 100 μm, but 100 to 15 μm is desired in view of the recent demand for low voltage driving. In addition, in order to obtain a larger displacement amount by applying a voltage to the piezoelectric ceramic laminated actuator, a method of increasing the number of laminated layers is used. By adopting the thin piezoelectric ceramic thickness as described above, the piezoelectric ceramic laminated actuator can be reduced in size. Therefore, the piezoelectric ceramic multilayer element according to the present invention can be sufficiently used.

  The external electrode 15 may be made of a conductive metal such as Ag, Ni, Cu, Au, Al, or an alloy thereof, but the external electrode 15 is mainly made of the same metal or the same alloy as the internal electrode. It is desirable to make it an ingredient. A lead wire 16 is connected and fixed to the external electrode 15 by solder 17, and the lead wire 16 serves to connect the external electrode 15 to an external voltage supply unit.

  A method for manufacturing a piezoelectric ceramic multilayer element according to the present invention will be described. First, calcined powder of piezoelectric ceramics such as PZT, binder made of acrylic or butyral organic resin, organic solvent such as MFG (methylpropylene glycol), BC (butyl carbitol) and DOP (dioctyl phthalate) BPBG (butyl phthalyl glycolate) and other plasticizers are mixed and dispersed to prepare a slurry, and the slurry becomes a piezoelectric ceramic 11 by a sheet molding method such as a known doctor blade method or calendar roll method. Make a green sheet.

  Next, for example, a binder, a plasticizer, and the like are added to and mixed with Ag / Pd powder to prepare a conductive paste, and this is printed on the upper surface of each green sheet to a thickness of 1 to 5 μm by screen printing. And while laminating a plurality of green sheets with conductive paste printed on the upper surface, laminating a plurality of green sheets with no conductive paste printed on the upper and lower surfaces of this laminate, and integrating them by hot press, The laminate is produced by firing at 1000 ° C. in an air atmosphere after performing a binder removal heat treatment by selecting a temperature between 400 and 500 ° C. according to the type of binder.

  FIG. 2 shows a process of insulating the internal electrodes of the sintered laminate every other layer. Moreover, the partial enlarged view was attached to each figure of each figure of FIG.2 (c)-FIG.2 (g). First, the laminated body 31 baked as shown in FIG. 2A is sliced into a predetermined size as shown in FIG. 2B along the cutting line 39, and sliced as shown in FIG. 2C. A resist coating 33 or a sheet resist is attached to the side surface of the laminated body 32 to form a resist film 33. Thereafter, every other exposed internal electrode layer is masked and exposed. Next, the resist in the exposed portion is removed, the internal electrodes are exposed every other layer as shown in FIG. 2 (d), and the ceramic film is aerosolized from the nozzle 34 by the aerosol deposition method as shown in FIG. 2 (e). The insulating ceramic film 35 is formed by ejecting the fine powder. Thereafter, the resist is completely peeled off, and the internal electrodes are insulated by the ceramic film every other layer as shown in FIG. The same process is applied to the side surface facing this side surface, and every other layer is insulated with ceramic so as to form a counter electrode structure. After that, as shown in FIG. 2G, an Ag external electrode paste containing a glass frit on the surface insulated with ceramic is formed by a screen printing method, dried and baked to form an external electrode 36. After forming the external electrode 36, the multilayer ceramic piezoelectric element of the present invention is manufactured by cutting into individual sizes and connecting lead wires with solder. In addition, the power supply for voltage application is connected, and polarization treatment is performed to obtain the multilayer ceramic piezoelectric actuator of the present invention.

Next, examples of the present invention will be further described. Piezoelectric ceramics calcined powder of 50 wt%, acrylic strain constant d ₃₃ = 850 pm / V, composition of 50 Pb (Ni, Nb) O ₃ -15PbZrO ₃ -35PbTiO ₃ and an average particle size of 0.7 μm Mix and disperse in a homogenizer with a composition of 5 wt% resin binder, 38 wt% methylpropylene glycol (MFG) as solvent, 10 wt% butyl carbitol (BC), and 2 wt% dioctyl phthalate (DOP) as plasticizer A slurry was prepared, and the slurry was adjusted to a thickness of 25 μm by a doctor blade method to prepare a ceramic green sheet.

Next, kneading was carried out with three rolls so that the composition had an average particle size of 0.5 μm, Ag / Pd = 80/20 powder 60 wt%, ethyl cellulose 4 wt% as binder, and terpineol 36 wt% as solvent. The screen mesh was formed by adjusting the various printing conditions using a 400 mesh mesh with a solid pattern of 2 μm thickness target by the screen printing method on the upper surface of the green sheet. Then, 200 green sheets on which Ag / Pd paste was printed were laminated, and 10 layers of green sheets on which no conductive paste was printed were laminated on the upper and lower surfaces of the laminate, and 70 ° C., 50 kgf It was integrated with a hot press under the conditions of / cm ² and 30 minutes. This laminate was debindered at 450 ° C. in an air atmosphere, and then fired at 1000 ° C. in an air atmosphere. The thickness of the internal electrode was 1.5 μm, the thickness of the piezoelectric ceramic was 20 μm, the piezoelectric ceramic, and the internal electrode A laminate having 200 layers was obtained.

  Then, the laminated body sintered by the wire saw was made into the slice body of thickness 2mm perpendicular | vertical with respect to the lamination direction. A resist was coated on the surface of the sliced laminated body where the internal electrodes were exposed to form a resist film. Then, exposure processing and resist removal were performed with a plate that can mask every other layer on the exposed end portion of the internal electrode, and masking processing was performed on every other layer. Subsequently, a PZT powder having an average particle size of 0.5 μm was prepared, and was coated with a ceramic to a thickness of 5 μm so as to form a film over the entire surface by an aerosol deposition method on the exposed uncovered internal electrode end. Thereafter, all of the adhering resist was removed, and a structure in which internal electrodes were insulated every other layer was produced. Further, the same treatment was applied to the opposing surfaces, and the internal electrodes were insulated every other layer with ceramic so that the internal electrodes formed a counter electrode structure.

  Next, 50 wt% of Ag powder having an average particle diameter of 5 μm, 5 wt% of amorphous borosilicate glass powder having a softening point of 600 ° C. having an average particle diameter of 5 μm as a main component, and ethyl cellulose as a binder. A silver glass conductive paste was prepared by mixing in a three roll mill so that 5 wt% and terpineol as a solvent would be 40 wt%, and all the internal electrodes exposed on the surface of the laminate on which the ceramic insulation was formed Printing was performed to a thickness of 10 μm by screen printing so as to be connected, and baking was performed at an air atmosphere of 800 ° C. to form external electrodes. And in order to make it an individual actuator, it cut | disconnected so that it might become an element of 2 mm width with a wire saw, and obtained the piezoelectric ceramic laminated layer element whose shape is 2 mm x 2 mm x 4.6 mm. Thereafter, lead wires were connected to the external electrodes by soldering, and polarization treatment was performed by applying 50 V for 15 minutes to the positive and negative external electrodes via the lead wires, thereby producing a multilayer ceramic piezoelectric actuator.

As a result of applying a DC voltage of 10 V to the obtained multilayer piezoelectric actuator, a displacement amount as designed value of 1.5 μm was obtained in the lamination direction. Further, the insulation resistance value was 8.0 × 10 ⁸ Ω, and sufficient insulation properties could be secured.

1A and 1B show a piezoelectric ceramic multilayer element according to an embodiment of the present invention, in which FIG. 1A is a perspective view, FIG. 1B is a longitudinal sectional view along the line AA, and FIG. Sectional drawing which shows the junction part of an electrode and an external electrode. FIG. 2 (a) shows a process of slicing a laminated body, FIG. 2 (b) is a diagram of a sliced laminated body, showing a process of insulating every other layer of internal electrodes of the laminated body according to the present invention. FIG. 2C is a diagram of a process of forming a resist film on a sliced laminate, FIG. 2D is a diagram of a process of exposing internal electrodes every other layer, and FIG. 2E is a ceramic film. FIG. 2 (f) is a diagram showing a process of forming by the aero deposition method, FIG. 2 (f) is a diagram showing a state in which the internal electrodes are insulated by a ceramic film every other layer, and FIG. The figure which shows the state cut | disconnected in. FIG. 3A shows a conventional piezoelectric ceramic multilayer actuator element, FIG. 3B is a perspective view thereof, FIG. 3B is a longitudinal sectional view taken along the line BB, and FIG. 3C is an internal electrode and an external electrode. The schematic cross section which expands and shows a junction part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Piezoelectric ceramic 12 Internal electrode 13 Laminated body 14 Ceramic insulator 15 External electrode 16 Lead wire 17 Solder 24 Insulating glass 31 Sintered laminated body 32 Sliced laminated body 33 Resist film 34 Nozzle 35 Insulating ceramic film 36 External electrode 39 Cutting line

Claims (3)

  Piezoelectric ceramic layers and internal electrode layers are alternately laminated, and the end portions of the internal electrode layers are exposed on the outer side surface of the laminate, and have a plurality of ceramic insulators that insulate the end portions every other layer. In the method of manufacturing a piezoelectric ceramic multilayer element having external electrodes that connect the end portions that have not been formed, the process of forming the ceramic insulator is performed by applying a photosensitive resist to the entire outer side surface where the end portions of the internal electrode layers are exposed. Forming a resist layer by coating or applying a dry sheet resist, and subjecting the resist layer to an exposure process so as to mask every other end of the internal electrode layer, and partially using a developer. A step of removing, a step of forming an insulating ceramic film by an aerosol deposition method on the outer side surface where the internal electrode layer is exposed every other layer, and a step of removing all remaining resist layers Method of manufacturing a piezoelectric ceramic multilayer element characterized by having a. The insulating ceramic layer is composed of a ceramic mainly composed of lead zirconate titanate (Pb (Zr, Ti) O ₃ ), alumina (Al ₂ O ₃ ), zirconia oxide (ZrO ₂ ), and barium titanate (BaTiO ₃ ). The method for manufacturing a piezoelectric ceramic multilayer element according to claim 1, comprising:   3. A piezoelectric ceramic multilayer actuator, wherein an actuator is formed using the piezoelectric ceramic multilayer element obtained by the method for manufacturing a piezoelectric ceramic multilayer element according to claim 1.

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