JP5536310B2 - Multilayer piezoelectric element and method for manufacturing the same - Google Patents

Description

  The present invention relates to a piezoelectric element having a multilayer structure (multilayer piezoelectric element) used as an ultrasonic transducer, a piezoelectric actuator, or the like, and further relates to a method for manufacturing such a multilayer piezoelectric element.

  A piezoelectric body typified by a material having a lead-based perovskite structure such as PZT (lead zirconate titanate) produces a piezoelectric effect that expands and contracts when a voltage is applied. Piezoelectric elements having such properties are used in various applications such as ultrasonic transducers, piezoelectric actuators, and piezoelectric pumps.

  The structure of the piezoelectric element is basically a single-layer structure in which electrodes are formed on both sides of one piezoelectric body, but the miniaturization and integration of the piezoelectric element accompanying the recent development of MEMS (micro electro mechanical system) related equipment. As a result, stacked piezoelectric elements in which a plurality of piezoelectric bodies and a plurality of electrodes are alternately stacked are also used. In such a piezoelectric element, the capacitance of the entire piezoelectric element can be increased by connecting electrodes for applying an electric field to a plurality of piezoelectric layers in parallel. Even if it is made small, an increase in electrical impedance can be suppressed.

  11A and 11B are cross-sectional views for explaining a conventional method for manufacturing a multilayer piezoelectric element. As shown in FIG. 11A, a laminated structure is formed by alternately laminating three piezoelectric layers 10 and two internal electrodes 21 and 22. Further, a side insulating film 23 is formed at a predetermined position on the side surface of the laminated structure. Then, the side electrodes 24 and 25, the lower electrode 26, and the upper electrode 27 are formed by coating an electrode material around the laminated structure.

  Next, the side electrode 24 is separated from the lower electrode 26 and the side electrode 25 is separated from the upper electrode 27 by removing portions G and H shown in FIG. 11B using a dicing saw. Thereby, the short circuit between the lower electrode 26 and the upper electrode 27 is released, and an electric field can be applied to each of the three piezoelectric layers 10.

  By the way, when the frequency of the ultrasonic wave transmitted and received by the ultrasonic probe increases, it becomes necessary to reduce the thickness of the piezoelectric element. Accordingly, it is necessary to reduce the width of the side insulating film formed on the side surface of the laminated structure. As a method for forming an insulating film on the side surface of the laminated structure, an emulsion electrodeposition method, a photolithography method, a printing method, and a dispensing method are used, and these methods reduce the width of the insulating film. Whether or not it is possible to deal with is a problem.

  In the resin emulsion electrodeposition method, since the diameter of the emulsion particles is generally as large as about 50 μm or more, it is the limit to narrow the width of the insulating film to about 100 μm. A glass emulsion electrodeposition method has also been proposed. However, if glass, which is a hard material, is used as an insulating film, the electromechanical coupling coefficient k of the piezoelectric body is lowered. For example, in the 33 vibration mode, which is a vibration mode when a piezoelectric body subjected to polarization processing (polling processing) in the third direction (Z-axis direction) is vibrated by applying an electric field in the same third direction. When the electromechanical coupling coefficient k33 is compared, when k33 of the piezoelectric body is 0.74, k33 is about 0.68 or more when resin is used as the insulating film, but k33 is 0 when glass is used as the insulating film. It decreases to about 60 to 0.62.

  According to the photolithography method in which the resist film is exposed and patterned, it is possible to form a fine pattern on the order of submicron, but it is difficult to form a thick resist film to form an insulating film. Even if the film can be formed thick, the pattern becomes rough. Furthermore, in the photolithography method, the time required for each process is long, and in the development process, the piezoelectric element is immersed in an alkaline chemical solution or the resist material is baked at a high temperature. It is a problem.

  When the screen printing method is used, the precision of the plate is insufficient and the alignment of the screen is difficult. In forming an insulating film by the dispensing method, the lower limit of the width of the insulating film is mainly defined by the size of the dispensing nozzle. According to the combination of the inner diameter of a dispense nozzle currently on the market and the viscosity of the insulating material that can be applied, the limit of the width of the insulating film is about 90 μm to 100 μm. Although it is conceivable to use a high-viscosity insulating material, such an insulating material cannot be stably supplied from a dispensing nozzle having a small inner diameter.

  As a related technique, Patent Document 1 discloses a method for manufacturing a multilayer piezoelectric ceramic element capable of forming an insulating layer at a low temperature of 500 ° C. or lower. In this manufacturing method, insulation is performed so that the internal electrodes exposed on the side surfaces of the laminated body are laminated so that there are three or more piezoelectric ceramic layers and two or more internal electrodes become counter electrodes every other layer. A method of manufacturing a multilayer piezoelectric ceramic element having an external electrode thereon, characterized in that an insulating material is formed by applying a paste-like insulating material with a dispenser.

However, high frequency is desired in the ultrasonic probe, and it is necessary to create an ultrasonic probe that transmits and receives ultrasonic waves having a center frequency of 10 MHz to 15 MHz. In that case, the thickness of the piezoelectric element is 120 μm to 150 μm, and in the case of a laminated piezoelectric element having a two-layer or three-layer structure, the thickness of one layer is 40 μm to 75 μm. Therefore, it is becoming difficult to form an insulating film by a dispensing method.
JP 2004-79825 A (page 2-3, FIG. 3)

  Accordingly, in view of the above points, an object of the present invention is to accurately form a side insulating film even on a thin laminated structure in a laminated piezoelectric element used as an ultrasonic transducer, a piezoelectric actuator, or the like. .

In order to solve the above problems, a multilayer piezoelectric element according to one aspect of the present invention is (i) a multilayer structure in which a plurality of piezoelectric layers and at least one internal electrode are alternately stacked, The first side surface includes a first region and a second region adjacent to the first region and having a lower surface energy of the piezoelectric body than the first region, and an end portion of at least one internal electrode is A laminated structure located in the second region on any side surface; and (ii) at least a second region on the first side surface of the laminated structure, and includes a part of a cylinder or a curved surface And (iii) a first plane formed on one main surface of the laminated structure, and having at least one side surface insulating film that covers the end of at least one internal electrode in the second region. And (iv) a second flat surface formed on the other main surface of the laminated structure. (V) a first electrode or a second planar electrode continuously formed on the first side surface of the laminated structure, and an odd number of the first and second planar electrodes and at least one internal electrode. A first side electrode connected to the first electrode group as the second electrode, and (vi) a first and second planar electrode and at least one interior formed on the second side surface of the laminated structure And a second side electrode connected to a second electrode group that does not belong to the first electrode group.

In addition, a method for manufacturing a multilayer piezoelectric element according to one aspect of the present invention includes a step (a) of manufacturing a multilayer structure in which a plurality of piezoelectric layers and at least one internal electrode are alternately stacked, and a mask. Is used to change the surface energy of the piezoelectric body to at least a part of the first side surface of the multilayer structure so that at least the first side surface is adjacent to the first region and the first region. Separating the second region whose surface energy of the piezoelectric body is lower than that of the first region and setting the end of at least one internal electrode within the second region on either side surface ( b) and at least one side surface insulating film covering an end of at least one internal electrode in the second region of at least the first side surface of the laminated structure so as to have a shape including a part of a cylinder or a curved surface. In the second area A step (c) of selectively forming, a first planar electrode is formed on one main surface of the multilayer structure, and a second planar electrode is formed on the other main surface of the multilayer structure; A first side electrode connected to a first electrode group that is an odd-numbered electrode among the first and second planar electrodes and at least one internal electrode is provided on the first side surface of the structure. Alternatively, the first planar electrode may be formed continuously with the second planar electrode, and may not belong to the first electrode group among the first and second planar electrodes and at least one internal electrode on the second side surface of the stacked structure. ; and a (d) forming a second side electrode connected to the second electrode group.

According to the present invention, to form a difference in surface energy of the piezoelectric body in at least a first side surface of the laminated structure, having a low surface energy area of the piezoelectric body, a shape including a part or a curved surface of a cylinder the By forming the side insulating film that covers the end portion of the internal electrode in the region, the side insulating film can be accurately formed even for the thin laminated structure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a perspective view showing a multilayer piezoelectric element according to the first embodiment of the present invention. This multilayer piezoelectric element includes a multilayer structure in which three piezoelectric layers 10, first internal electrodes 11 and second internal electrodes 12 are alternately stacked, and one side surface of the multilayer structure (in the drawing). A side insulating film 13a formed on the right side), a side insulating film 13b formed on the other side (left side in the figure) of the laminated structure, side electrodes 14 and 15, a lower electrode 16, an upper electrode 17, have. Although three piezoelectric layers 10 are shown in FIG. 1, the number of piezoelectric layers may be four or more. When there are five or more piezoelectric layers, the multilayer structure includes a plurality of first internal electrodes 11 and a plurality of second internal electrodes 12.

  As shown in FIG. 1, regions A and B having lower surface energy than adjacent regions are formed on both side surfaces of the piezoelectric layer 10 so that the right end portion of the internal electrode 11 is in the region A on the right side. The left end portion of the internal electrode 12 is located in the region B on the left side surface. This facilitates the formation of the side insulating films 13a and 13b, as will be described later. The side insulating film 13a covers the right end portion of the internal electrode 11 in the region A on the right side surface of the stacked structure, and the side insulating film 13b is the left end portion of the internal electrode 12 in the region B on the left side surface of the stacked structure. Is covered. Since each of the side surface insulating films 13a and 13b has a shape including a part of a cylinder or a curved surface, it is easy to form the side electrodes 14 and 15, and the side electrodes 14 and 15 are difficult to cut.

  Here, the side electrodes 14 and 15, the lower electrode 16, and the upper electrode 17 may be formed simultaneously or separately. In any case, the side electrode 14 is connected to the lower electrode 16 and the second internal electrode 12 which are odd-numbered electrodes, and is insulated from the first internal electrode 11 and the upper electrode 17 which are even-numbered electrodes. The The side electrode 15 is connected to the first internal electrode 11 and the upper electrode 17 which are even-numbered electrodes, and is insulated from the lower electrode 16 and the second internal electrode 12 which are odd-numbered electrodes. When a voltage is applied between the lower electrode 16 and the upper electrode 17, an electric field is applied to each of the three piezoelectric layers 10, and the stacked piezoelectric element expands and contracts as a whole due to the piezoelectric effect in each piezoelectric layer 10.

  The piezoelectric layer 10 has a thickness of about 40 μm to 50 μm, for example, and the long side of the bottom surface is about 3 mm to 4 mm, for example. The piezoelectric layer 10 is formed using a piezoelectric material such as PZT (lead zirconate titanate).

Each of the first and second internal electrodes 11 and 12 has a thickness of about 1 μm to 3 μm, for example, and may be formed of one type of material or a plurality of different materials. It may have a multilayer structure. In the former example, a metal material such as platinum (Pt) or silver palladium (Ag—Pd) is used. In the latter example, an adhesion layer formed to a thickness of about 50 nm using titanium oxide (TiO ₂ ) and a conductive layer formed to a thickness of about 3 μm using platinum (Pt). A two-layer structure is used.

The side insulating films 13a and 13b are formed of a highly insulating resin such as epoxy, silicone, urethane acrylate, or oxetane, for example. In such a resin, the Young's modulus, 1.3 × and ¹⁰ 9 ^Pa~2.0 × ¹⁰ 9 Pa, very small compared to glass. Therefore, when the piezoelectric layer 10 tries to expand and contract, the side insulating films 13a and 13b can also follow the expansion and contraction (displacement) of the piezoelectric layer 10. Therefore, the displacement of the piezoelectric layer 10 caused by the side insulating films 13a and 13b. There is almost no braking.

  As the side electrodes 14 and 15, the lower electrode 16, and the upper electrode 17, for example, an electrode of one kind of material selected from gold (Au), platinum (Pt), titanium (Ti), etc., chromium An electrode having a two-layer structure of (Cr) and gold (Au) or an electrode having a three-layer structure of nickel (Ni), titanium (Ti), and platinum (Pt) is used.

  Next, a laminated piezoelectric element according to the second embodiment of the present invention will be described. In the second embodiment, a case where two piezoelectric layers are formed will be described. Other points are the same as in the first embodiment.

  FIG. 2 is a perspective view showing a multilayer piezoelectric element according to the second embodiment of the present invention. The multilayer piezoelectric element includes a multilayer structure in which two piezoelectric layers 10 and internal electrodes 11 are alternately stacked, and a side insulating film formed on one side surface (left side in the figure) of the multilayer structure. 13, side electrodes 18 and 19, a lower electrode 16, and an upper electrode 17.

  As shown in FIG. 2, a region C having a surface energy lower than that of the adjacent region is formed on one side surface (left side in the drawing) of the laminated structure, so that the left end portion of the internal electrode 11 is a region on the left side surface. It is located in C. This facilitates the formation of the side surface insulating film 13 as will be described later. The side insulating film 13 covers the left end portion of the internal electrode 11 in the region C on the left side surface of the laminated structure. Since the side insulating film 13 has a shape including a part of a cylinder or a curved surface, it is easy to form the side electrodes 18 and 19 and the side electrodes 18 and 19 are not easily cut.

  Here, the side electrode 18, the lower electrode 16, and the upper electrode 17 may be formed simultaneously or separately. In any case, the side electrode 18 is connected to the lower electrode 16 and the upper electrode 17 which are odd-numbered electrodes, and is insulated from the internal electrode 11 which is an even-numbered electrode. The side electrode 19 is connected to the internal electrode 11 that is an even-numbered electrode, and is insulated from the lower electrode 16 and the upper electrode 17 that are odd-numbered electrodes. When a voltage is applied between the lower electrode 16 and the side electrode 19, an electric field is applied to each of the two piezoelectric layers 10, and the multilayer piezoelectric element expands and contracts as a whole due to the piezoelectric effect in each piezoelectric layer 10.

Next, a method for manufacturing a multilayer piezoelectric element according to the third embodiment of the present invention will be described.
3A to 3G are views for explaining a method for manufacturing a multilayer piezoelectric element according to the third embodiment of the present invention. Here, as in the first embodiment, a case of manufacturing a laminated piezoelectric element having three piezoelectric layers will be described.

  First, as shown in FIG. 3A, a laminated structure is manufactured by laminating three piezoelectric layers 10, a first internal electrode 11 and a second internal electrode 12. The first internal electrodes 11 and the second internal electrodes 12 are alternately stacked with the piezoelectric layers 10 interposed therebetween. The thicknesses of the lower, middle, and upper piezoelectric layers 10 are, for example, about 40 μm, 50 μm, and 40 μm, respectively, and the long side of the bottom surface is, for example, about 3 mm to 4 mm.

  This laminated structure may be produced, for example, using a green sheet method, or may be produced by laminating a bulk material of a piezoelectric body on which internal electrodes are formed, or a powdery material may be used as a lower layer. Alternatively, an aerosol deposition (AD) method may be used in which the material is deposited by spraying at a high speed. The AD method is a film forming method that has recently attracted attention as a method for forming a ceramic film.

  Next, as illustrated in FIG. 3B, by using a mask, UV light (ultraviolet light) is irradiated to a partial region on each side surface of the stacked structure, thereby reducing the surface energy in that region. Thereby, as shown to FIG. 3C, the area | region A and B whose surface energy is lower than an adjacent area | region, and an adjacent area | region are isolate | separated. Since the wettability is improved in the regions A and B, the difference in surface tension between the regions A and B and the adjacent region increases, and the liquid resin applied to the regions A and B spreads to the adjacent region. It becomes difficult. Accordingly, a narrow side insulating film can be easily formed.

  Next, as shown in FIG. 3D, the resin 20 in a liquid state is applied to the regions A and B on the side surface of the laminated structure using a dispenser. As the resin 20, for example, a photocurable (including ultraviolet curable) synthetic resin or a thermosetting synthetic resin can be used. The liquid resin 20 discharged from the dispense nozzle of the dispenser is distributed along a region having a low surface energy (a region having a low surface tension) due to an edge effect in which the surface tension changes at the boundary between a plurality of regions having different surface energies. To do. Therefore, the dispensing operation becomes very easy. Normally, when the surface energy is uniform, when a side insulating film having a uniform thickness is to be formed, the trajectory through which the dispense nozzle passes and the main surface of the laminated structure must be substantially parallel. On the other hand, according to the present embodiment, since the boundary between the plurality of regions having different surface energies finally determines the width of the side insulating film, the height and parallel adjustment of the dispense nozzle can be made easier than before.

  Thereafter, the resin 20 in the liquid state is irradiated with light or heat is applied to cure the resin, and as shown in FIG. 3E, in the side regions A and B of the laminated structure, the side insulating film 13a and 13b is formed. Side insulating film 13a covers the end of internal electrode 11 on one side, and side insulating film 13b covers the end of internal electrode 12 on the other side.

  Next, as shown in FIG. 3F, an electrode material (conductive) is formed on the first and second main surfaces and the first and second side surfaces of the multilayer structure by, for example, physical vapor deposition such as sputtering. Material) 30 is coated. Here, the formation of the electrode material 30 may be performed continuously on the two main surfaces and the two side surfaces, or may be performed separately. In addition, the electrode material is not formed on the front surface and the back surface of the laminated structure.

  Next, as shown in FIG. 3G, notches E and F reaching the piezoelectric layer 10 are provided in a part of the laminated structure in which the electrode material is formed. As a result, the remaining electrode material forms an electrode (side electrode 15 and upper electrode 17) that is connected to the first internal electrode 11 and insulated from the second internal electrode 12, and the second internal electrode. The electrodes (side electrode 14 and lower electrode 16) connected to 12 and insulated from the first internal electrode 11 are formed.

  Next, a method for manufacturing a multilayer piezoelectric element according to the fourth embodiment of the present invention will be described. In the method for manufacturing a multilayer piezoelectric element according to the fourth embodiment, only the surface treatment process is different from that of the third embodiment (FIG. 3B), and the other points are the same as those of the third embodiment. .

  FIG. 4 is a view for explaining a method for manufacturing a multilayer piezoelectric element according to the fourth embodiment of the present invention. As shown in FIG. 4, a mask such as a resist mask is formed on the side surface of the stacked structure so as to cover a region other than a partial region. By subjecting the multilayer piezoelectric element to plasma treatment in this state, plasma surface treatment is performed only on a part of the region, and the surface energy in that region is reduced. Thereby, the area | region where surface energy is lower than an adjacent area | region, and an adjacent area | region are isolate | separated. Since the wettability is improved in the region where the surface energy is lower than that of the adjacent region, the difference in surface tension between the region and the adjacent region becomes large, and the liquid resin applied to the region becomes adjacent to the adjacent region. It becomes difficult to spread. Accordingly, a narrow side insulating film can be easily formed.

  FIG. 5 is a diagram illustrating an example of a plasma processing apparatus. Here, an atmospheric pressure plasma cleaning apparatus will be described as an example of the plasma processing apparatus. An atmospheric pressure plasma cleaning device is a device that generates a glow discharge state that usually occurs only under vacuum under atmospheric pressure by a special technique, and cleans the object to be processed with ions or electrons generated by the glow discharge state. It activates the surface of the treated body.

  As shown in FIG. 5, the atmospheric pressure plasma cleaning apparatus generates a discharge gas by mixing a gas cylinder 41 for supplying an argon gas, a gas cylinder 42 for supplying an oxygen gas, and argon gas and oxygen gas. A gas mixing / control unit 43 for controlling the flow rate of the gas, a reactor 44 to which a discharge gas is supplied, a power source unit 45 for applying a high-frequency voltage to the reactor 44, and an object to be processed (multilayer piezoelectric element) are placed. And an XY table 46. The gas mixing / control unit 43 includes mass flow controllers 43a and 43b for measuring and controlling the flow rates of argon gas and oxygen gas, and a mixer 43c for mixing argon gas and oxygen gas.

  The argon gas whose flow rate is controlled by the mass flow controller 43 a and the oxygen gas whose flow rate is controlled by the mass flow controller 43 b are mixed in the mixer 43 c, and the generated discharge gas is supplied to the reactor 44. In the reactor 44, when a high frequency voltage is applied between the two electrodes, a discharge is generated in the discharge gas, and a plasma jet is generated. By this plasma jet, the object to be processed can be cleaned and the surface of the object to be processed can be activated.

  Next, a method for manufacturing a multilayer piezoelectric element according to the fifth and sixth embodiments of the present invention will be described. In the multilayer piezoelectric element manufacturing method according to the fifth and sixth embodiments, only the surface treatment process is different from that of the third embodiment (FIG. 3B), and other points are different from those of the third embodiment. It is the same.

  FIG. 6 is a diagram for explaining a method for manufacturing a multilayer piezoelectric element according to the fifth embodiment of the present invention. In the fifth embodiment, the surface energy in the adjacent region is increased by forming a fine structure in the adjacent region of the partial region on the side surface of the laminated structure. Thereby, the adjacent region where the surface energy is increased is separated from the region where the surface energy is lower than the adjacent region.

  As shown in FIG. 6, a structure (pillar structure) in which fine protrusions are regularly arranged is provided in a region adjacent to the region A on the side surface of the laminated structure. When liquid is dropped on the surface provided with the pillar structure, the liquid is repelled and does not wet the surface. This is because the liquid is difficult to come into contact with the surface due to minute protrusions on the surface, and is water repellency based on the same principle as the phenomenon in which the lotus leaf repels water (the lotus leaf phenomenon). As a result, the difference in surface tension between the region A and the adjacent region becomes large, and the liquid resin applied to the region A hardly spreads to the adjacent region. Accordingly, a narrow side insulating film can be easily formed.

  FIG. 7 is a view for explaining the method for manufacturing the multilayer piezoelectric element according to the sixth embodiment of the present invention. In the sixth embodiment, a fine structure finer than that shown in FIG. 6 is formed in a part of the side surface of the laminated structure having a rough surface, so that the surface energy in that region is reduced. Thereby, the area | region where surface energy is lower than an adjacent area | region, and an adjacent area | region are isolate | separated.

  As shown in FIG. 7, a structure (pillar structure) in which fine protrusions are regularly arranged is provided in the region A on the side surface of the multilayer structure. Since this pillar structure is finer than the rough surface in the adjacent region, the liquid resin applied to the region A is difficult to spread in the adjacent region. Accordingly, a narrow side insulating film can be easily formed.

  Next, a method for manufacturing a multilayer piezoelectric element according to the seventh and eighth embodiments of the present invention will be described. In the multilayer piezoelectric element manufacturing method according to the seventh and eighth embodiments, only the surface treatment process is different from that of the third embodiment (FIG. 3B), and other points are different from those of the third embodiment. It is the same.

  FIG. 8 is a view for explaining the method for manufacturing the multilayer piezoelectric element according to the seventh embodiment of the present invention. In the seventh embodiment, by using a blast mask and applying sand blasting to a partial region on the side surface of the laminated structure by spraying fine particles with a weak spray pressure, the surface energy in that region is reduced. . Thereby, the area | region where surface energy is lower than an adjacent area | region, and an adjacent area | region are isolate | separated.

  The sand blasting device has a blasting device main body for supplying particles at a set pressure, and a nozzle for spraying the particles to the object to be processed (laminated piezoelectric element). In the present embodiment, sandblasting is performed at a pressure of 0.15 MPa to 0.20 MPa using particles having a particle size of several μm or less.

  FIG. 9 is a view for explaining the method for manufacturing the multilayer piezoelectric element according to the eighth embodiment of the present invention. In 8th Embodiment, the surface energy in an adjacent area | region raises by spraying a coarse particle with the strong spraying pressure to the adjacent area | region of the one part area | region in the side surface of a laminated structure, and performing a sandblasting process. Thereby, the adjacent region where the surface energy is increased is separated from the region where the surface energy is lower than the adjacent region. In the present embodiment, sand blasting is performed at a pressure of 0.20 MPa or more using particles having a particle size of 10 μm or more.

  According to the above embodiment, it becomes easy to form a side insulating film accurately even for a thin laminated structure. Therefore, the application range of the multilayer piezoelectric element is expanded, and for example, it is possible to laminate the piezoelectric body in an ultrasonic probe for a high frequency (10 MHz or more), which has been difficult in the past. Further, by utilizing the difference in surface tension between a plurality of regions having different surface energies, a side insulating film that is thicker than the conventional one can be formed even if the width is narrow, so that dielectric breakdown hardly occurs. Therefore, it is possible to drive at a high voltage in an ultrasonic transducer, a piezoelectric actuator, etc., and to increase the amplitude (displacement amount). Further, in the laminated structure, even when the internal electrode is wavy without being parallel to the main surface of the piezoelectric layer, the side insulating film can be prevented from protruding.

  FIG. 10 is a diagram comparing the shapes of the laminated structure and the side insulating film in the present invention and the conventional example. FIG. 10A is a side view and a cross-sectional view of the laminated structure and the side insulating film in the present invention. Since a difference in surface energy is formed on the side surface of the laminated structure, the side insulating film 13b is It is formed only in the region whose surface energy is lower than that of the adjacent region. Therefore, even if the internal electrodes 11 and 12 are wavy without being parallel to the main surface of the piezoelectric layer 10, the side insulating film 13b reliably covers the end of the internal electrode 12, while the side insulating film 13b A distance from the end of the internal electrode 11 is ensured. The accuracy of each part can be sufficiently secured by the accuracy (3 μm to 5 μm) of a processing machine such as a dicing saw.

  FIG. 10B is a side view and a cross-sectional view of the laminated structure and the side insulating film in the conventional example. If the side insulating film 23 reliably covers the end of the internal electrode 22, the distance between the side insulating film 23 and the end of the internal electrode 21 cannot be secured, and the side insulating film 23 becomes the end of the internal electrode 21. May be covered.

  The present invention can be used in a piezoelectric element (laminated piezoelectric element) having a laminated structure used as an ultrasonic transducer, a piezoelectric actuator, or the like.

1 is a perspective view showing a multilayer piezoelectric element according to a first embodiment of the present invention. It is a perspective view which shows the lamination type piezoelectric element which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 4th Embodiment of this invention. It is a figure which shows the example of a plasma processing apparatus. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 5th Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 6th Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 7th Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the laminated piezoelectric element which concerns on the 8th Embodiment of this invention. It is a figure which compares and shows the shape of the laminated structure and side surface insulating film in this invention and a prior art example. It is sectional drawing for demonstrating the manufacturing method of the conventional multilayer piezoelectric element. It is sectional drawing for demonstrating the manufacturing method of the conventional multilayer piezoelectric element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Piezoelectric layer 11 1st internal electrode 12 2nd internal electrode 13a, 13b Side surface insulating film 14, 15, 18, 19 Side surface electrode 16 Lower electrode 17 Upper electrode 20 Liquid state resin 30 Electrode material 41, 42 Gas cylinder 43 Gas mixing / control unit 43a, 43b Mass flow controller 43c Mixer 44 Reactor 45 Power supply unit 46 XY table AC Areas where surface energy is lower than adjacent areas E, F Notch

Claims (7)

A laminated structure in which a plurality of piezoelectric layers and at least one internal electrode are alternately laminated, and at least on a first side surface, adjacent to the first region and the first region, from the first region A second region having a low surface energy of the piezoelectric body, and the laminated structure in which an end of the at least one internal electrode is located in the second region on any side surface;
The laminated structure is selectively formed in at least a second region of the first side surface and has a shape including a part of a cylinder or a curved surface, and an end of the at least one internal electrode in the second region At least one side insulating film covering
A first planar electrode formed on one main surface of the multilayer structure;
A second planar electrode formed on the other main surface of the multilayer structure;
An odd-numbered electrode among the first and second planar electrodes and the at least one internal electrode formed continuously with the first or second planar electrode on the first side surface of the multilayer structure. A first side electrode connected to the first electrode group,
Formed on the second side surface of the multilayer structure and connected to a second electrode group that does not belong to the first electrode group among the first and second planar electrodes and the at least one internal electrode. A second side electrode;
A laminated piezoelectric element comprising: A step (a) of producing a laminated structure in which a plurality of piezoelectric layers and at least one internal electrode are alternately laminated;
Using a mask, at least a part of the first side surface of the multilayer structure is subjected to a process of changing the surface energy of the piezoelectric body, so that at least the first region and the first region are formed on the first side surface. A state in which the second region having a lower surface energy of the piezoelectric body than the first region is adjacently separated, and an end portion of the at least one internal electrode is located in the second region on any side surface; Step (b) to perform,
At least one side surface insulating film that covers an end portion of the at least one internal electrode in the second region of at least the first side surface of the multilayer structure has a shape including a part of a cylinder or a curved surface. A step (c) of selectively forming in the second region;
On the first side surface of the multilayer structure, a first planar electrode is formed on one main surface of the multilayer structure, a second planar electrode is formed on the other main surface of the multilayer structure, and In addition, a first side electrode connected to a first electrode group that is an odd-numbered electrode among the first and second planar electrodes and the at least one internal electrode is defined as the first or second plane. A second electrode that is formed continuously with an electrode and does not belong to the first electrode group among the first and second planar electrodes and the at least one internal electrode on the second side surface of the multilayer structure; (d) forming a second side electrode connected to the electrode group,
A method for manufacturing a laminated piezoelectric element comprising: The step (b) includes lowering the surface energy of the piezoelectric body in the second region by irradiating at least the second region of the first side surface of the multilayer structure with ultraviolet rays. A method for manufacturing a laminated piezoelectric element of the above. The step (b) includes reducing the surface energy of the piezoelectric body in the second region by performing plasma surface treatment on at least the second region of the first side surface of the multilayer structure. The manufacturing method of the lamination type piezoelectric element of description. The step (b) increases the surface energy of the piezoelectric body in the first region by forming a microstructure in at least the first region or the second region of the first side surface of the multilayer structure; or The method for manufacturing a multilayer piezoelectric element according to claim 2, comprising reducing the surface energy of the piezoelectric body in the second region. The step (b) reduces the surface energy of the piezoelectric body in the second region by sandblasting at least the second region or the first region of the first side surface of the multilayer structure; or The method for manufacturing a multilayer piezoelectric element according to claim 2, comprising raising the surface energy of the piezoelectric body in the first region. Step (c) uses a dispenser to apply a resin in a liquid state to at least a second region of at least a first side of the laminated structure, and then cures the resin to provide at least one side insulation. The method for manufacturing a multilayer piezoelectric element according to claim 2, comprising forming a film.

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