JP5558936B2 - Method for manufacturing laminated element and laminated element - Google Patents

Description

  The present invention relates to a method for manufacturing a laminated element including a laminated body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated.

  A multilayer ceramic capacitor (MLCC) or a multilayer piezoelectric element includes a multilayer body in which a plurality of ceramic layers and a plurality of internal electrode layers are alternately stacked, and a plurality of internal electrode layers in the multilayer body are provided on a side surface of the multilayer body. Since the electric field strength applied to the ceramic layer is larger than that of the non-laminated type under the same voltage conditions applied to the entire element, Under the same voltage condition, a larger capacitor capacity and strain displacement can be obtained, and under the same characteristic condition, a lower voltage can be driven.

  Electronic components such as various chip components, piezoelectric components, and sensor-related components that use these multilayer elements are required to have high integration, high density, high reliability, and high frequency. Is considered as one of the key technologies for the simultaneous firing process of ceramic green sheets and electrodes.

  In general, the simultaneous firing process of ceramic green sheets and electrodes is performed by dispersing ceramic powder into a binder and molding the ceramic powder by the doctor blade method, etc., and then pasting the electrode material in resin or organic solvent on the green sheet. A dielectric film with an electrode is produced by forming a pattern by a screen printing method or the like, and a plurality of them are laminated, and then each binder is removed and fired.

  As described above, the laminated co-firing process has a complicated process because the ceramic and the electrode material have a binder mixing step, a sheet molding step, and a binder removing step. In addition, the electrodes between each layer are aligned at the time of stacking, but high-reliability elements are required because high-accuracy alignment is required in consideration of misalignment due to the subsequent press process and side electrode formation process. It is difficult to manufacture with good yield.

  Various methods for aligning laminated sheets with high accuracy and highly reliable co-fired processes have been studied. For example, Patent Document 1 discloses a method for manufacturing a ceramic laminate that can be laminated with high accuracy by pressure bonding in the state where the pressure at the central portion is higher than the peripheral portion of the sheet during lamination. ing.

  Patent Document 2 discloses a method for forming a side electrode in a multilayer piezoelectric element by exposing one side surface of an internal electrode to apply a magnetic force and removing the stacked body moved by the magnetic force as a defective product. Has been.

JP 2009-246298 A JP 2009-176767 A

  In the method of Patent Document 1, although the positioning accuracy is improved, the process such as pressure control at the time of pressure bonding is rather complicated. Further, according to the method of Patent Document 2, the reliability of the final product is improved, but the laminated body cannot be manufactured with a high yield.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a multilayer element by a multilayer co-firing process capable of positioning with high accuracy by a simple process.
Another object of the present invention is to provide a laminated element that can be manufactured by a simple process and in which electrodes are aligned with high accuracy.

The method for manufacturing a laminated element of the present invention includes a laminated body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated, and a pair of external electrodes formed on a side surface of the laminated body, In the method for manufacturing a laminated element in which a plurality of internal electrode layers are alternately conducted with the pair of external electrodes,
Forming a dielectric layer on one surface of the metal electrode sheet to form a dielectric sheet with electrodes;
Using the two dielectric sheets with electrodes, the dielectric layers of the respective sheets are sandwiched in a folded state so that they are inside, and the two sheets are alternately overlapped, and each Forming a laminate in which a part of the electrodes becomes the pair of external electrodes;
The laminated body is pressed in a direction substantially parallel to the laminating direction and has a step of pressure-contacting the alternately laminated dielectric sheets with electrodes.

  The method for manufacturing a laminated element of the present invention can be suitably used when the dielectric layer is a piezoelectric layer.

The dielectric layer is preferably a composite layer in which ceramic powder is dispersed in a resin. In such a configuration, the dielectric layer can be formed by a coating method, and the pressure-contacting step is performed at a temperature equal to or higher than the glass transition temperature of the resin, whereby a laminated element with good adhesion is obtained. be able to.
The resin is preferably a resin having a relative dielectric constant of 15 or more, and a resin mainly composed of cyanoethylated pullulan. In the present specification, the “main component” is defined as a component having a content of 80% by mass or more.

The multilayer element of the present invention includes a multilayer body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately stacked, and a pair of external electrodes formed on a side surface of the multilayer body, In the laminated element in which the electrode layer is alternately conducted with the pair of external electrodes,
The pair of external electrodes and the internal electrode layer connected to each external electrode are formed of a continuous metal layer.

  In the laminated element of the present invention, the continuous metal layer is preferably made of a metal foil. Moreover, it is preferable that the said continuous metal layer has aluminum as a main component.

  In the method for manufacturing a laminated element of the present invention, a metal sheet is used as an electrode layer, and two dielectric sheets with electrodes having a dielectric layer formed thereon are used, and the dielectric layers of each sheet are on the inside. A laminated element is manufactured by sandwiching two sheets in a state of being folded into two. In such a configuration, by a simple method of simply sandwiching the dielectric sheet with electrodes in a folded state, a highly accurate and reliable laminated co-firing process can be performed, and the side electrode forming step as a subsequent step is performed. It can be unnecessary. Therefore, according to the present invention, it is possible to very easily manufacture a laminated element with side electrodes in which internal electrodes are aligned with high accuracy.

Schematic sectional view showing the manufacturing process of the multilayer element according to the first embodiment of the present invention (No. 1) Schematic sectional view showing the manufacturing process of the multilayer element according to the first embodiment of the present invention (No. 2) Schematic sectional view showing the manufacturing process of the multilayer element according to the first embodiment of the present invention (No. 3) Schematic sectional view showing the manufacturing process of the multilayer element according to the first embodiment of the present invention (No. 4) Schematic sectional view showing the manufacturing process of the multilayer element according to the first embodiment of the present invention (No. 5) Schematic sectional view showing the manufacturing process of the multilayer element according to the first embodiment of the present invention (No. 6) Schematic sectional view showing the manufacturing process of the laminated element of the second embodiment according to the present invention (part 1) Schematic sectional view showing the manufacturing process of the laminated element of the second embodiment according to the present invention (part 2) Schematic sectional view showing the manufacturing process of the laminated element of the second embodiment according to the present invention (part 3) Schematic sectional view showing the manufacturing process of the laminated element of the second embodiment according to the present invention (part 4) Schematic sectional view showing the manufacturing process of the laminated element of the second embodiment according to the present invention (No. 5) Schematic sectional view showing the manufacturing process of the laminated element of the second embodiment according to the present invention (No. 6)

"Laminated element and manufacturing method thereof"
A multilayer element and a manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. 1A to 1F are schematic cross-sectional views showing the manufacturing process of the first manufacturing method of the multilayer piezoelectric element 1 (multilayer element 1), and FIGS. 2A to 2F show the multilayer piezoelectric element 1 (multilayer element 1). It is a schematic sectional drawing which shows the manufacturing process of the 2nd manufacturing method of). In order to facilitate visual recognition, the scale of each part is appropriately changed and shown.

  As shown in FIGS. 1F and 2F, the multilayer piezoelectric element 1 is formed on a side surface of a multilayer body in which a plurality of piezoelectric layers 22 and a plurality of internal electrode layers 21a are alternately stacked. The plurality of internal electrodes 21a and the pair of external electrodes 21b are configured such that the internal electrode layers 21a adjacent to each other in the stacking direction are opposed to the external electrodes 21b (external electrodes 21b on the left side in the drawing). And the external electrode 21b on the right side), and a pair of external electrodes 21b and the internal electrode layer 21a connected to each external electrode 21b are formed of a continuous metal layer 11. The two metal layers 11 are insulated from each other.

<First manufacturing method>
As shown in FIG. 1A to FIG. 1F, the laminated piezoelectric element 1 (laminated element 1) has a metal electrode sheet 11 (FIG. 1A), and a piezoelectric layer (dielectric material) on one surface of the metal electrode sheet 11. Layer) 12 to form a piezoelectric sheet with electrode (dielectric sheet with electrode) 10 (FIG. 1B), and using two piezoelectric sheets with electrode 10, the piezoelectric of each sheet 10 The body layer 12 is sandwiched in a folded state so as to be inward to form a laminate in which the two sheets 10 are alternately overlapped and a part of each electrode sheet 11 becomes a pair of external electrodes 21b. And a step of pressing the laminated body in the laminating direction and press-contacting the electrode-attached piezoelectric sheets 11 alternately stacked.

  In the first manufacturing method, first, two sheets 10 are folded in substantially half (FIG. 1C), and sandwiched so that the openings of the folded sheets 10 overlap (FIG. 1D) to form a laminate. After that, pressure is applied in the stacking direction (FIG. 1E) to manufacture the stacked piezoelectric element 1.

First, the metal electrode sheet 11 is prepared (FIG. 1A).
The main component of the metal electrode sheet 11 is not particularly limited, and examples thereof include metals such as Al, Pt, Pd, Au, Ag, Ni, and Cu, or alloys thereof. Moreover, the thickness of the metal electrode sheet 11 will not be restrict | limited especially if it is the thickness which does not produce mixing of a crack and a fracture | rupture by bending. Since the metal has ductility, a suitable thickness varies depending on its constituent elements, but in consideration of handleability, it is preferably about several μm to 100 μm, and more preferably a metal foil of 10 μm or more. Al foil is most preferable in terms of easy availability, low cost, and handling.

  If the metal electrode sheet 11 is too thin to handle easily when the piezoelectric layer 12 is formed, a carrier film is bonded to the surface of the metal electrode sheet 11 opposite to the film forming surface of the piezoelectric layer 12. It is preferable. Since the carrier film reinforces the thinness of the metal electrode sheet 11 and is peeled off during the bending process, the carrier film has rigidity that makes it easy to handle and is easy to peel off. There must be something. As such a carrier film, a resin film having a film thickness of several tens of μm and a pressure sensitive adhesive that can be easily peeled off due to UV irradiation is preferable. For example, a commercially available UV sheet (Furukawa Electric Co., Ltd.) Company UV sheet: UC-110M-120) is preferred.

  Next, the piezoelectric layer 12 is formed on the metal electrode sheet 11 to form the electrode-attached piezoelectric sheet 11 (FIG. 1B).

  The thickness of the piezoelectric layer 12 needs to be a thickness that does not cause cracks or breakage when bent in a subsequent process. Since the upper limit of the thickness varies depending on the material of the piezoelectric layer 12, it is preferable to design appropriately according to the required piezoelectric performance and the material.

  The constituent material of the piezoelectric layer 12 is not particularly limited, and is an inorganic film containing a perovskite type oxide, a tungsten bronze type oxide, a bismuth layered oxide, etc., and any one type or two or more types of oxides exhibiting piezoelectricity. It may be a film in which such an inorganic oxide is dispersed in a resin binder, or a polymer film having piezoelectricity.

  Perovskite oxides exhibiting piezoelectricity include lead titanate, lead zirconate titanate (PZT), lead zirconate, lead lanthanum titanate, lead lanthanum zirconate titanate, lead zirconate titanate magnesium niobate, and nickel niobium Lead-containing compounds such as lead zirconate titanate, and non-lead-containing compounds such as barium titanate, potassium niobate, and bismuth sodium titanate.

  The method for forming the piezoelectric layer 12 is not particularly limited, and can be appropriately selected according to the constituent material of the piezoelectric layer 12. When the piezoelectric layer 12 is an inorganic film, a sputtering method, a PLD method, an aerosol deposition method, a vapor phase growth method, or a liquid phase method such as a sol-gel method may be used. When the piezoelectric layer 12 is an inorganic film, it becomes a layer with poor flexibility, and thus the thickness that does not break in the bending step is relatively thin (for example, 0.1 μm to 5 μm). However, in the case of an inorganic film, the characteristics of the oxide having piezoelectricity can be utilized as they are, so that the layer thickness may be relatively thin.

  In an aspect in which the piezoelectric layer 12 is a piezoelectric layer formed by dispersing the inorganic oxide in a resin binder, the ceramic powder that has already been fired at a high temperature may be dispersed in the resin binder. preferable. In such an embodiment, the resin binder is not particularly limited, but in the multilayer element manufacturing method of the present embodiment, since the resin binder does not need to be removed, a high dielectric resin having a relative dielectric constant of 15 or more. It is preferable that a high voltage can be applied.

  A high dielectric resin having a relative dielectric constant of 15 or more is mainly composed of polysaccharides such as cellulose and pullulan, and hydroxyl groups such as polyvinyl alcohol and polyhydroxyethyl methacrylate which are cyanoethylated (preferably cyanoethylation rate of 60% or more). Resins are preferred. Such a polymer is preferable because of the large polarization of the cyano group, having a very high relative dielectric constant, good heat resistance, colorless and transparent, high dielectric properties, and high adhesion based on a polar structure.

  In the embodiment using the resin binder, the two electrode-attached piezoelectric sheets 10 are pressed in the post-process in a direction substantially parallel to the laminating direction, but the pressure is pressed in a state where the resin binder is soft. However, since adhesiveness becomes favorable, it is preferable. In order to press the resin binder in a soft state, it is preferably in a heated atmosphere at the time of pressing, and is preferably pressed at a temperature equal to or higher than the glass transition temperature of the resin (hot press). Of the binders described above, cyanoethylated pullulan (for example, cyanoresin CR-S (cyanoethylation rate 90%) manufactured by Shin-Etsu Chemical Co., Ltd.) has a glass transition temperature of around 90 ° C. and is hot pressed by heating at about 100 ° C. Is easy to handle and is particularly preferable.

  Also in the embodiment using the resin binder, the film thickness of the piezoelectric layer 12 needs to be a thickness that does not cause a crack due to bending in the subsequent process. However, since the binder is excellent in flexibility, it is rather at the time of bending. In consideration of the thickness of the metal electrode sheet that is the base, it may be designed appropriately according to the required performance and the size of the element. Suitable thickness of the piezoelectric layer 12 is, for example, 5 μm to 100 μm, and preferably several tens of μm. Even if a microcrack or the like is generated in the piezoelectric layer 12 by bending, it is considered that the influence is small because distortion is easily relaxed in the above-described hot press mode.

  In the embodiment using the resin binder, the film formation method of the piezoelectric layer 12 is not particularly limited, but it is preferable to form the film by a coating method. In the film formation by the coating method, the preparation method of the coating liquid is not particularly limited, but the resin binder is dissolved in the solvent at a concentration that allows the ceramic powder to be dispersed well and the film formability is good. An example is a method of kneading ceramic powder. The method for kneading the ceramic powder is not particularly limited, but it can be kneaded using a centrifuge or the like.

  Next, the prepared coating solution is coated on the electrode sheet 11 and then dried to remove the solvent, thereby obtaining the piezoelectric layer 12. The coating method of the coating solution is not particularly limited, but a film forming method using a coating machine such as a film applicator is preferable.

Two piezoelectric sheets with electrodes are produced as described above.
Next, each electrode-attached piezoelectric sheet 10 is folded so that the piezoelectric layer 12 is on the inside (FIG. 1C), and the two electrode-attached piezoelectric sheets 10 are folded together as shown in FIG. 1D. A laminated body is formed by sandwiching, and as shown in FIG. 1E, pressure is applied in a direction substantially parallel to the laminating direction (in the direction of the arrow in the figure) to press the two electrode-attached piezoelectric sheets 10 together to form a laminated type. The piezoelectric element 1 is obtained (FIG. 1F).

  As already described, in the embodiment using a resin binder as the piezoelectric layer 12, it is preferable to heat to a temperature equal to or higher than the glass transition temperature of the resin binder at the time of pressurization and / or after pressure contact. It is preferable that the resin binder has a temperature equal to or higher than the glass transition temperature because the resin 12 can be fused and the adhesiveness between the two electrode-attached piezoelectric sheets 10 can be improved.

In the multilayer piezoelectric element 1, as shown in FIG. 1F, a part of the electrode sheet 11 corresponding to a fold of the folded piezoelectric sheet 10 with electrode forms a side electrode 21 b, and the remaining part of the electrode sheet 11 is formed. A plurality of internal electrodes 21a are formed. In addition, the piezoelectric layers 12 sandwiched in a bent state become a plurality of piezoelectric layers 22.
The multilayer piezoelectric element 1 can be manufactured as described above.

  In the manufacturing method of the multilayer piezoelectric element 1 (multilayer element 1) of the present embodiment, the piezoelectric layers (dielectric layers) 12 of the respective piezoelectric sheets with electrodes (dielectric sheets with electrodes) 10 are on the inner side. The laminated piezoelectric element 1 is manufactured by sandwiching the two sheets 10 in a folded state. In such a configuration, it is possible to perform a highly accurate and reliable laminated co-firing process by a simple method of simply sandwiching the electrode-attached piezoelectric sheet 10 in a folded state, and a side electrode forming step which is a subsequent step Can be made unnecessary. Therefore, according to the present invention, the multilayer piezoelectric element 1 with side electrodes in which the internal electrodes are aligned with high accuracy can be manufactured very easily.

<Second production method>
The second manufacturing method of the multilayer piezoelectric element 1 will be described with reference to FIGS. 2A to 2F, but the manufacturing process of the piezoelectric sheet with electrode 10 shown in FIGS. 2A and 2B is the first manufacturing method. Since it is the same as that, description is abbreviate | omitted.

  In the first manufacturing method, the two piezoelectric sheet with electrodes 10 are folded and then sandwiched to form a laminated body. However, in the second manufacturing method, first, as shown in FIG. The electrode-attached piezoelectric sheet 10 is overlaid so that the electrode sheets 11 and the piezoelectric layers 12 are alternated, and then the electrode sheet 11 is folded so as to be the uppermost layer and the lowermost layer to form a laminate. (FIG. 2D). By folding in this way and applying pressure in a direction substantially parallel to the laminating direction (in the direction of the arrow in the figure) in the same manner as in the first manufacturing method (FIG. 2E), the two piezoelectric sheet with electrodes 10 are brought into pressure contact with each other. As in the first manufacturing method, a part of the electrode sheet 11 corresponding to the fold mountain of the folded piezoelectric sheet 10 with electrode forms the side electrode 21b, and the remaining part of the electrode sheet 11 forms the plurality of internal electrodes 21a. The piezoelectric layers 12 configured and sandwiched in a bent state become a plurality of piezoelectric layers 22 (FIG. 2F).

  Since the second manufacturing method is the same as the first manufacturing method except that the formation process of the laminate is different, the aspect and manufacturing conditions of each preferable component are the same as those of the first manufacturing method, and the effects thereof. Is obtained in the same manner as in the first manufacturing method.

  In the above embodiment, the case where the multilayer element is a multilayer piezoelectric element has been described, but the dielectric layer is not limited to a piezoelectric body.

(Design changes)
The present invention is not limited to the above-described embodiment, and the design can be changed as appropriate without departing from the spirit of the present invention.

Examples and comparative examples according to the present invention will be described.
Example 1
<Pretreatment of electrode sheet>
Prepare 10 sheets of aluminum sheet (aluminum foil) with a thickness of 10 μm, and two sheets with a 90 μm thickness of UV sheet (UV sheet manufactured by Furukawa Electric Co., Ltd .: UC-110M-120) attached as a carrier film. did.

<Preparation of coating solution>
First, cyanoresin CR-S manufactured by Shin-Etsu Chemical Co., Ltd. was prepared, mixed in a dimethylformamide (DMF) solvent at a ratio of 30 wt.%, And dissolved for half a day to prepare a binder solution. Next, lead zirconate titanate (PZT) powder was put into the binder solution, and the mixed solution was kneaded at 2000 rpm for 20 minutes using a centrifuge to prepare a coating solution.

<Deposition of piezoelectric layer>
Using an applicator, a coating solution is applied to the surface of two prepared electrodes with a carrier film so as to have an average film thickness of 100 μm, and then naturally dried to obtain a piezoelectric layer having an average film thickness of 40 μm. The carrier film was peeled off by irradiating with UV light (wavelength 350 to 360 nm) for 5 minutes from the carrier film side to obtain two piezoelectric sheets with electrodes.

<Formation of laminate>
The piezoelectric sheet with electrodes is folded in half and then sandwiched, hot pressed for 5 minutes at about 100 ° C and 100 MPa using a press molding machine (Mini Test Press 10 manufactured by Toyo Seiki Co., Ltd.), then naturally cooled and laminated. A type piezoelectric element was obtained. When the interface between the electrode layer and the piezoelectric layer of the obtained multilayer piezoelectric element was confirmed by an electron microscope, the smoothness was good in both the upper and lower sides, and no voids or the like were found inside the piezoelectric layer.

  The multilayer element of the present invention is preferably used for a multilayer actuator, an ink jet recording head, a magnetic recording / reproducing head, a MEMS (Micro Electro-Mechanical Systems) device, a micro pump, a piezoelectric actuator mounted on an ultrasonic probe, and the like. it can.

1. Multilayer piezoelectric element (multilayer element)
10 Piezoelectric sheet with electrode (dielectric sheet with electrode)
11 Metal electrode sheet 12, 22 Piezoelectric layer (dielectric layer)
21a Internal electrode layer 21b External electrode

Claims (11)

A laminated body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated; and a pair of external electrodes formed on a side surface of the laminated body, wherein the plurality of internal electrode layers are the pair of external electrodes. In the manufacturing method of the laminated element alternately conducted with the external electrode,
Forming a dielectric layer on one surface of the metal electrode sheet to form a dielectric sheet with electrodes;
Using the two dielectric sheets with electrodes, the dielectric layers of the respective sheets are sandwiched and folded so as to be inside, and the two sheets are alternately overlapped, and each Forming a laminate in which one electrode is the pair of external electrodes;
Becomes sequentially have a step of pressing the electrode with dielectric sheets between which the laminate is pressurized in the stacking direction and a direction substantially parallel overlapping said alternately,
The method for producing a laminated element, wherein the dielectric layer is a composite layer in which ceramic powder is dispersed in a resin .   The method for manufacturing a multilayer element according to claim 1, wherein the dielectric layer is a piezoelectric layer. Wherein the pressure to process, manufacturing method of a multilayer element according to claim 1 or 2 any one which comprises carrying out at glass transition temperature above a temperature of the resin. The method for manufacturing a laminated element according to any one of claims 1 to 3 , wherein the resin is a resin having a relative dielectric constant of 15 or more. The method for producing a laminated element according to claim 4 , wherein the resin is a resin mainly composed of cyanoethylated pullulan. Method for manufacturing a laminated element of claims 1 to 5 or 1, wherein said forming a film by a coating method the dielectric layer. A laminated body in which a plurality of dielectric layers and a plurality of internal electrode layers are alternately laminated; and a pair of external electrodes formed on a side surface of the laminated body, wherein the plurality of internal electrode layers are the pair of external electrodes. In laminated elements that are alternately conducted with external electrodes,
Wherein a pair of the external electrodes, Ri Do from each said internal electrode layer and a metal layer which is continuous, which is electrically connected to the external electrodes,
The multilayer element, wherein the dielectric layer is a composite layer in which ceramic powder is dispersed in a resin .   The multilayer element according to claim 7, wherein the continuous metal layer is made of a metal foil. The laminated element according to claim 7 , wherein the continuous metal layer contains aluminum as a main component. The laminated element according to any one of claims 7 to 9 , wherein the resin is a resin having a relative dielectric constant of 15 or more. The laminated element according to claim 10 , wherein the resin is a resin mainly composed of cyanoethylated pullulan.

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