JP2010219464A - Laminated piezoelectric element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated piezoelectric element miniaturizing the element itself and improving reliability and performance. <P>SOLUTION: A through-hole conductor 6 in an element body 2 for electrically connecting a first external electrode 12, a first electrode 32 and a fourth electrode 52 to one another, a second through-hole conductor 8 in the element body 2 for electrically connecting a second external electrode 14, a second electrode 34 and a third electrode 54 to one another, and a ground through-hole conductor 7 in the element body 2 for electrically connecting a ground external electrode 13 and ground electrodes 43, 63 to one another are arranged at a longitudinal center position of the element body 2, and respectively arranged in the width direction of the element body 2. Thereby, reliability is improved by preventing reception of influence of the surrounding environment and relaxing stress acting on the respective through-hole conductors 6, 7, 8. By making the element body 2 easily deform, and thereby allowing displacement in drive to be increased, performance is improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a multilayer piezoelectric element.

  As the stacked piezoelectric element, a first piezoelectric element layer in which an upper electrode divided into two is formed, a second piezoelectric element layer in which an internal ground electrode is formed under the first piezoelectric element layer, and a second piezoelectric element An internal electrode having a symmetrical pattern with respect to the upper electrode formed on the first piezoelectric element layer with respect to the laminated surface is formed below the element layer, and the lower electrode is formed on the opposite side of the surface on which the internal electrode is formed. In order to electrically connect the piezoelectric body having the third piezoelectric element layer and the electrode patterns in the diagonal direction among the electrode patterns formed on the first piezoelectric element layer and the third piezoelectric element layer of the piezoelectric body. And a third side electrode for electrically connecting the internal ground electrode of the second piezoelectric element layer of the piezoelectric body and the lower electrode of the third piezoelectric element layer. Vibration generated from the electrode and piezoelectric body Which comprises a power transmission member for transmitting are known (e.g., see Patent Document 1).

JP 2007-275895 A

  However, the laminated piezoelectric element described above has side electrodes for electrically connecting the electrodes provided on the upper and lower parts of the piezoelectric element layer, so that it is in contact with other components when incorporated in an external device. Therefore, there is a problem in that the mounting area of the element increases due to the increase in the size of components. In addition, since the side electrodes connecting the electrodes are exposed to the outside of the element, there is a possibility of causing a problem in reliability due to the influence of the surrounding environment. Furthermore, since these side electrodes are in close contact with the outer surface of the piezoelectric element, the deformation of the piezoelectric element may be hindered, thereby reducing the performance. In particular, when the side electrode is a print-baked electrode, glass is contained in the adhesive, which greatly affects the deformation of the piezoelectric element.

  An object of the present invention is to provide a multilayer piezoelectric element capable of reducing the size of the element and improving the reliability and performance.

  The multilayer piezoelectric element according to the present invention is formed by laminating a plurality of piezoelectric layers, and is opposed to the rectangular parallelepiped element having the first and second main surfaces and the first and second main surfaces. And a first electrode including an electrode portion disposed on one end side from the center position in the longitudinal direction of the element body, and an electrode portion disposed on the other end side from the center position. A first internal electrode layer having a second electrode electrically insulated from the electrode, an electrode portion of the first electrode of the first internal electrode layer and an electrode of the second electrode with the piezoelectric layer sandwiched on the second main surface side A ground electrode layer having a ground electrode disposed in the element body so as to oppose the portion, and disposed in the element body so as to face the ground electrode layer with the piezoelectric layer sandwiched on the second main surface side, from the center position Is also arranged on the other end side with respect to the third electrode including the electrode portion arranged on one end side, and the center position A second internal electrode layer having a fourth electrode that is electrically insulated from the third electrode portion, and a first external electrode that is formed on the first main surface and is electrically insulated from each other, The external electrode layer having the second external electrode and the ground external electrode, and the first external electrode, the first electrode, and the fourth electrode are electrically connected to each other by extending in the thickness direction, which is the direction in which the piezoelectric layer is laminated in the element body. A first through-hole conductor connected to the second body, a second through-hole conductor extending in the thickness direction in the element body and electrically connecting the second external electrode, the second electrode, and the third electrode, and the element body in the thickness direction. A ground through-hole conductor that extends and electrically connects the ground external electrode and the ground electrodes, and the first through-hole conductor, the second through-hole conductor, and the ground through-hole conductor are disposed at the center position, That It is arranged in the width direction of the element body, characterized in that cause bending vibration in the thickness direction with produce longitudinal vibration in the longitudinal direction.

  In the laminated piezoelectric element according to the present invention, the first external electrode, the first through-hole conductor in the element body that electrically connects the first electrode and the fourth electrode, the second external electrode, the second electrode, and the third electrode The second through-hole conductor in the element that electrically connects the electrodes and the ground through-hole conductor in the element that electrically connects the ground external electrode and the ground electrodes are located at the center in the longitudinal direction of the element. They are arranged and arranged in the width direction of the element bodies. In this way, since the electrodes are electrically connected by the through-hole conductors formed in the element body, it is possible to design without considering contact with other parts and a side electrode is provided. Compared to the case, it is possible to reduce the size of the parts. In addition, since the through-hole conductor connecting the electrodes is provided inside the element body, it can be prevented from being influenced by the surrounding environment, and the reliability can be improved. Here, the first electrode and the fourth electrode having a diagonal positional relationship with respect to the center position in the longitudinal direction of the element body with the ground electrode interposed therebetween are electrically connected and the second electrode having the same positional relationship And the third electrode are electrically connected, so the laminated piezoelectric element generates longitudinal vibration in the longitudinal direction and bending vibration in the thickness direction with the center position of the element body as a node (position where no amplitude is generated in vibration) However, in the multilayer piezoelectric element according to the present invention, each through-hole conductor is formed at a central position as a node, so that stress acting on each through-hole conductor can be relieved and reliability can be improved. it can. Furthermore, the structure around the element body portion provided with the through-hole conductor is softened, but the structure around the element body center position is deformed by providing a plurality of through-hole conductors at the center position in the longitudinal direction of the element body. It becomes easy to do. As a result, the displacement during driving can be increased without increasing the internal stress acting on the element body, and the performance can be improved. As described above, the device can be miniaturized and the reliability and performance can be improved.

  In the multilayer piezoelectric element according to the present invention, the first through-hole conductor, the second through-hole conductor, and the ground through-hole conductor formed in one piezoelectric layer are formed in adjacent piezoelectric layers in the thickness direction. It is preferable that the first through-hole conductor, the second through-hole conductor, and the ground through-hole conductor do not overlap with each other when viewed in the thickness direction. In this way, by arranging the through-hole conductors in a staggered arrangement in which the positions of the piezoelectric layers are shifted for each piezoelectric layer, stress concentration and poor connection can be reduced as compared with the case where they are provided at the same position when viewed from the thickness direction. it can.

  According to the present invention, it is possible to reduce the size of an element and improve reliability and performance.

1 is a perspective view of a multilayer piezoelectric element according to a first embodiment of the present invention. It is sectional drawing along the II-II line | wire shown in FIG. FIG. 2 is a developed perspective view of the multilayer piezoelectric element shown in FIG. 1. It is the figure which showed each vibration mode of a lamination type piezoelectric element. It is the figure which showed a mode that a laminated piezoelectric element drives a rotor. It is a flowchart which shows the manufacturing method of the lamination type piezoelectric element which concerns on this embodiment. It is a perspective view which shows the laminated body obtained by a lamination | stacking and press process. It is a figure which shows the magnitude | size of the displacement at the time of the drive of the laminated piezoelectric element which concerns on this embodiment, and the conventional laminated piezoelectric element. FIG. 4 is a developed perspective view of an element body of a multilayer piezoelectric element according to a second embodiment of the present invention, corresponding to FIG. 3. FIG. 4 is a developed perspective view of an element body of a multilayer piezoelectric element according to a third embodiment of the present invention, corresponding to FIG. 3. It is sectional drawing along the XI-XI line shown in FIG. FIG. 6 is a developed perspective view of an element body of a multilayer piezoelectric element according to a fourth embodiment of the present invention, corresponding to FIG. 3. It is a perspective view of the lamination type piezoelectric element concerning the modification of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

[First embodiment]
With reference to FIGS. 1-3, the structure of the multilayer piezoelectric element which concerns on 1st embodiment of this invention is demonstrated. FIG. 1 is a perspective view of a multilayer piezoelectric element 1 according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II shown in FIG. FIG. 3 is a developed perspective view of the multilayer piezoelectric element 1 shown in FIG. 2 and 3, a one-dot chain line CL is attached to the center in the longitudinal direction of the multilayer piezoelectric element. In FIG. 3, since the through hole is very small, it is omitted, and a through hole conductor is formed at a position where an alternate long and short dash line passes in the drawing.

  As shown in FIG. 1, the laminated piezoelectric element 1 has a function of moving a rotor 3 that is a driven body by being driven by being applied with an AC voltage. The laminated piezoelectric element 1 includes a rectangular parallelepiped element 2 formed by laminating and integrating a plurality of piezoelectric layers, and friction chips 4A and 4B that move in contact with the rotor 3. . The element body 2 of the multilayer piezoelectric element 1 includes a rectangular first main surface 2a that is an upper surface in FIG. 1 and a rectangular second main surface 2b that is a lower surface. In the following description, the long side direction of the first and second main surfaces 2a, 2b is the "longitudinal direction" of the element body 2, the short side direction is the "width direction" of the element body 2, and the first and second main surfaces. The direction in which 2a and 2b face each other, that is, the stacking direction in which the piezoelectric layers are stacked is referred to as the “thickness direction” of the element body 2. The element body 2 is set to have a longitudinal direction size of 1 to 20 mm, a width direction size of 1 to 10 mm, and a thickness direction size of about 0.2 to 5 mm.

  An external electrode layer 11 serving as an external electrode when another external device is mounted is formed at the longitudinal center position of the first main surface 2a of the element body 2. The external electrode layer 11 is arranged in the width direction at the center position in the longitudinal direction of the first main surface 2a, and the first external electrode 12, the ground external electrode 13, and the second external electrode that are electrically insulated from each other. 14. The first external electrode 12 is formed in a rectangular shape at one end in the width direction and connected to the voltage output terminal of the external device, and the ground external electrode 13 is formed in a rectangular shape at the center position in the width direction and externally connected. Connected to the ground terminal of the device, the second external electrode 14 is formed in a rectangular shape at the other end in the width direction and connected to the voltage output terminal of the external device. The first external electrode 12, the ground external electrode 13, and the second external electrode 14 are transferred at a predetermined temperature (for example, about 700 ° C.) after transferring an electrode paste mainly composed of Ag or the like to the first main surface 2a of the element body 2. It is formed by baking with electroplating and further electroplating. Ni / Au or the like can be used for electroplating.

  Friction tips 4 </ b> A and 4 </ b> B for moving the rotor 3 are attached to the second main surface 2 b of the element body 2. The friction tips 4A and 4B are made of cemented carbide, zirconia, or alumina, and are attached by cutting a cylindrical member into a semicircular cross section and bonding the cut surfaces to two portions of the second main surface 2b. ing. When the size of the element body 2 in the longitudinal direction is L, the friction tips 4A and 4B are semi-cylindrical in the width direction of the element body 2 at a position 1 / 3L from one end 2c in the longitudinal direction of the element body 2, respectively. Is attached so that the semi-cylinder extends in the width direction of the element body 2 at a position 1 / 3L from the other end 2d in the longitudinal direction of the element body 2 (see FIG. 2).

  As shown in FIGS. 2 and 3, rectangular plate-shaped piezoelectric layers 10, 20, 30, 40, 50, 60, 70 having piezoelectric characteristics (that is, deformed when energized), and relay electrode layers 21, a first internal electrode layer 31, a first ground electrode layer (ground electrode layer) 41, a second internal electrode layer 51, and a second ground electrode layer 61 are stacked. The relay electrode layer 21, the first internal electrode layer 31, the first ground electrode layer (ground electrode layer) 41, the second internal electrode layer 51, and the second ground electrode layer 61 are composed of the piezoelectric layers 10 and 20 in the element body 2. , 30, 40, 50, 60, 70 are arranged one by one along the stacking direction (that is, the thickness direction of the element body 2). At the time of manufacture, the external electrode layer 11 described above is formed on the upper surface of the piezoelectric layer 10 to be the first main surface 2a of the element body 2, and the relay electrode layer 21 is formed on the upper surface of the piezoelectric layer 20, The internal electrode layer 31 is formed on the upper surface of the piezoelectric layer 30, the first ground electrode layer 41 is formed on the upper surface of the piezoelectric layer 40, the second internal electrode layer 51 is formed on the upper surface of the piezoelectric layer 50, The two ground electrode layers 61 are formed on the upper surface of the piezoelectric layer 60. In the actual multilayer piezoelectric element 1, the plurality of piezoelectric layers 10, 20, 30, 40, 50, 60, 70 are integrated to such an extent that the boundary between them cannot be visually recognized.

  The piezoelectric layers 10, 20, 30, 40, 50, 60, 70 are made of, for example, a piezoelectric ceramic material mainly composed of PZT (lead zirconate titanate). Moreover, the thickness of the piezoelectric layers 10, 20, 30, 40, 50, 60, 70 is, for example, about 10 to 100 μm.

  The relay electrode layer 21 is arranged in the width direction at the center position in the longitudinal direction of the piezoelectric layer 20 and is electrically insulated from the first relay electrode 22, the ground relay electrode 23, and the second relay electrode 24. It is configured. The first relay electrode 22 is formed in a rectangular shape at one end in the width direction, the ground relay electrode 23 is formed in a rectangular shape extending in the width direction at the center position in the width direction, and the second relay electrode 24 is formed in the other direction in the width direction. It is formed in a rectangular shape on the end side.

  The first internal electrode layer 31 includes a first electrode 32, a ground relay electrode 33, and a second electrode 34 that are electrically insulated from each other. The ground relay electrode 33 is formed in a rectangular shape so as to overlap the upper ground relay electrode 23 when viewed from the thickness direction at the center position in the longitudinal direction. The first electrode 32 includes an electrode portion 32 a disposed on the one end 2 c side (that is, on the one end 30 c side of the piezoelectric layer 30) from the center position in the longitudinal direction of the element body 2, and a relay formed at the center position in the longitudinal direction. The electrode part 32b is provided. The electrode portion 32a is formed in a rectangular shape so as to cover substantially the entire region of the upper surface of the piezoelectric layer 30 on the one end 30c side of the ground relay electrode 33. The relay electrode part 32b is formed in a rectangular shape so as to protrude from the electrode part 32a to the center position in the longitudinal direction and to overlap the upper first relay electrode 22 as viewed from the thickness direction. The second electrode 34 includes an electrode portion 34a disposed on the other end 2d side (that is, the other end 30d side of the piezoelectric layer 30) with respect to the longitudinal center position of the element body 2, and a longitudinal center position. And a relay electrode portion 34b to be formed. The electrode portion 34a is formed in a rectangular shape so as to cover substantially the entire region of the upper surface of the piezoelectric layer 30 on the other end 30d side of the ground relay electrode 33. The relay electrode part 34b protrudes from the electrode part 34a to the center position in the longitudinal direction, and is formed in a rectangular shape so as to overlap the upper second relay electrode 24 when viewed from the thickness direction.

  The first ground electrode layer 41 includes a first relay electrode 42, a ground electrode 43, and a second relay electrode 44 that are electrically insulated from each other. The ground electrode 43 is formed in a substantially rectangular shape so as to cover substantially the entire upper surface of the piezoelectric layer 40. Specifically, the ground electrode 43 is formed so as to overlap all of the upper electrode part 32a, the electrode part 34a, and the ground relay electrodes 23 and 33 when viewed from the thickness direction, and at the center position in the longitudinal direction, Rectangular recesses are formed on both ends of the piezoelectric layer 40 in the width direction. A first relay electrode 42 and a second relay electrode 44 are formed in the recess, respectively, and the first relay electrode 42 is formed so as to overlap the relay electrode portion 32b and the first relay electrode 22 when viewed from the thickness direction. The second relay electrode 44 is formed so as to overlap the relay electrode portion 34 b and the second relay electrode 24.

  The second internal electrode layer 51 includes a third electrode 54, a ground relay electrode 53, and a fourth electrode 52 that are electrically insulated from each other. The ground relay electrode 53 is formed in a rectangular shape so as to overlap the upper ground relay electrodes 23 and 33 when viewed from the thickness direction at the center position in the longitudinal direction. The third electrode 54 includes an electrode portion 54a disposed on the one end 2c side (that is, the one end 50c side of the piezoelectric layer 50) from the center position in the longitudinal direction of the element body 2, and a relay formed at the center position in the longitudinal direction. The electrode part 54b is provided. The electrode portion 54a is formed in a rectangular shape so as to cover substantially the entire area of the upper surface of the piezoelectric layer 50 on the one end 50c side of the ground relay electrode 53, so that the upper electrode portion 32a and the ground electrode are seen from the thickness direction. It is formed so as to overlap a part of 43. The relay electrode portion 54b is formed in a rectangular shape so as to protrude from the electrode portion 54a to the center position in the longitudinal direction and overlap the upper second relay electrodes 24 and 44 and the relay electrode portion 34b as viewed from the thickness direction. Further, the fourth electrode 52 includes an electrode portion 52a disposed on the other end 2d side (that is, the other end 50d side of the piezoelectric layer 50) with respect to the longitudinal center position of the element body 2, and a longitudinal center position. And a relay electrode portion 52b to be formed. The electrode portion 52a is formed in a rectangular shape so as to cover substantially the entire area of the upper surface of the piezoelectric layer 50 on the other end 50d side of the ground relay electrode 53, whereby the upper electrode portion 34a and the ground are seen from the thickness direction. It is formed so as to overlap a part of the electrode 43. The relay electrode portion 52b is formed in a rectangular shape so as to protrude from the electrode portion 52a to the center position in the longitudinal direction and overlap the upper first relay electrodes 22 and 42 and the relay electrode portion 32b as viewed from the thickness direction.

  The second ground electrode layer 61 includes a first relay electrode 62, a ground electrode 63, and a second relay electrode 64 that are electrically insulated from each other. The ground electrode 63 is formed in a substantially rectangular shape so as to cover substantially the entire upper surface of the piezoelectric layer 60. Specifically, the ground electrode 63 is formed so as to overlap all of the upper electrode portions 32a and 52a, the electrode portions 34a and 54a, and the ground relay electrodes 23, 33, and 53 as viewed in the thickness direction, and the longitudinal direction. At the center position in the direction, rectangular recesses are formed on both ends in the width direction of the piezoelectric layer 60. A first relay electrode 62 and a second relay electrode 64 are formed in the recesses, respectively. When viewed from the thickness direction, the first relay electrode 62 is connected to the relay electrode portions 32b and 52b and the first relay electrodes 22 and 42. The second relay electrode 64 is formed so as to overlap the relay electrode portions 34 b and 54 b and the second relay electrodes 24 and 44.

  In the first relay electrodes 22, 42, 62, the relay electrode portions 32 b, 52 b and the piezoelectric layers 10, 20, 30, 40, 50, 60, 70, through holes (through holes penetrating in the thickness direction) (Not shown) is formed, and the first through-hole conductor 6 is formed. Thus, the first external electrode 12, the first relay electrode 22, the first electrode 32, the first relay electrode 42, the fourth electrode 52, and the first relay electrode 62 are electrically connected to each other. Further, the center position in the longitudinal direction of the ground relay electrodes 23, 33, 53 and the ground electrodes 43, 63 and the corresponding positions in the piezoelectric layers 10, 20, 30, 40, 50, 60, 70 are in the thickness direction. A penetrating through hole (not shown) is formed, and a ground through hole conductor 7 is formed. As a result, the ground external electrode 13, the ground relay electrode 23, the ground relay electrode 33, the ground electrode 43, the ground relay electrode 53, and the ground electrode 63 are electrically connected to each other. Further, in the second relay electrodes 24, 44, 64, the relay electrode portions 34 b, 54 b and the piezoelectric layers 10, 20, 30, 40, 50, 60, 70, through positions penetrating in the thickness direction A hole (not shown) is formed, and a second through-hole conductor 8 is formed. Accordingly, the second external electrode 14, the second relay electrode 24, the second electrode 34, the second relay electrode 44, the third electrode 54, and the second relay electrode 64 are electrically connected to each other. Accordingly, the first through-hole conductor 6, the ground through-hole conductor 7, and the second through-hole conductor 8 are arranged at the center position in the longitudinal direction of the element body 2 and are arranged in the width direction of the element body 2, respectively. It becomes the composition which becomes. These through-hole conductors include a conductive material. The conductive material contained in each through-hole conductor may be made of one or more metals selected from the group consisting of Pd, Ag, Cu, W, Mo, Sn and Ni, or an alloy containing one or more of the above metals. preferable. The diameter of each through-hole conductor is, for example, about 20 to 100 μm.

  The element body 2 composed of the electrode layers and the piezoelectric layer is composed of thickness adjusting layers LY1, LY2 and a drive layer LY3 that vibrates the element body 2. The drive layer LY3 includes a first internal electrode layer 31, a piezoelectric layer 30, a first ground electrode layer 41, a piezoelectric layer 40, a second internal electrode layer 51, a piezoelectric layer 50, and a second ground electrode layer 61. ing. The thickness adjusting layer LY1 includes the piezoelectric layer 10, the relay electrode layer 21, and the piezoelectric layer 20. The thickness adjusting layer LY2 includes a piezoelectric layer 60 and a piezoelectric layer 70. The thickness adjusting layers LY1 and LY2 can adjust the frequency of vibration by polishing the piezoelectric element and adjusting the thickness at the time of manufacture. Further, since the thickness adjustment layers LY1 and LY2 have substantially the same thickness, the thickness adjustment layer LY1, the drive layer LY3, and the thickness adjustment layer LY2 are symmetrical in the thickness direction.

  In the drive layer LY3, the piezoelectric layer 30 sandwiched between the first internal electrode layer 31 and the first ground electrode layer 41, and the piezoelectric layer sandwiched between the first ground electrode layer 41 and the second internal electrode layer 51. 40, and the piezoelectric layer 50 sandwiched between the second internal electrode layer 51 and the second ground electrode layer 61 are each subjected to polarization treatment. In the polarization process, the first internal electrode layer 31 is polarized toward the first ground electrode layer 41, and the second internal electrode layer 51 is polarized toward the first ground electrode layer 41.

  Next, the operation of the multilayer piezoelectric element 1 will be described with reference to FIGS. FIG. 4 is a diagram showing each vibration mode of the multilayer piezoelectric element 1. FIG. 5 is a diagram showing a state in which the laminated piezoelectric element 1 drives the rotor 3. The multilayer piezoelectric element 1 has two resonance modes when driven. Specifically, a longitudinal vibration mode that vibrates in the longitudinal direction of the element body 2 as shown in FIG. It vibrates by superposing bending vibration modes in the thickness direction of the element body 2 as shown in 4 (b). The resonance frequency of the longitudinal vibration mode and the resonance frequency of the bending vibration mode are matched by polishing the thickness adjusting layers LY1 and LY2 (see FIG. 2) of the element body 2. FIG. 5 shows a state in which the longitudinal vibration mode and the bending vibration mode are overlapped. The active portion A1 including the first electrode 32, the ground electrode 43, and the piezoelectric layer 30, and the fourth electrode 52 are shown. When the active portion A4 composed of the ground electrode 43, the ground electrode 63, the piezoelectric layer 40, and the piezoelectric layer 50 is driven, the friction tip 4B moves the rotor 3 as shown in FIG. On the other hand, the active portion A2 composed of the second electrode 34, the ground electrode 43, and the piezoelectric layer 30, and the third electrode 54, the ground electrode 43, the ground electrode 63, the piezoelectric layer 40, and the piezoelectric layer 50 are configured. When the active part A3 to be driven is driven, the friction tip 4A moves the rotor 3 as shown in FIG. Further, when the first external electrode 12 and the second external electrode 14 are driven by applying a voltage whose phase is shifted by 90 degrees, elliptical motions whose phases are shifted by 180 degrees are generated in the friction tips 4A and 4B, respectively, and the rotor is alternately rotated. The frictional force acts on 3 and the rotor 3 can be moved.

  2 and 5, the vibration described above has a node (vibration) between a longitudinal center position of the element body 2, a position 1/6 L from one end 2 c, and a position 1/6 L from the other end 2 d. ), One end 2c, the other end 2d, a position 1 / 3L from one end 2c (that is, a position where the friction tip 4A is attached), and a position 1 / 3L from the other end 2d ( That is, the position at which the friction tip 4B is attached) is defined as a position where the maximum amplitude is generated.

  Next, a method for manufacturing the multilayer piezoelectric element 1 according to this embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a method for manufacturing the multilayer piezoelectric element 1 according to this embodiment. As shown in FIG. 6, the manufacturing process of the multilayer piezoelectric element 1 starts from the coating process S1. In this coating process S1, a piezoelectric material, which is a material of the piezoelectric layers 10 to 70, a solvent and a binder are mixed to form a coating. Next, sheeting process S2 is performed. In the sheet forming step S2, the paint formed in S1 on the pet film is formed into a sheet per piezoelectric layer.

  When the sheet forming step S2 is completed, a through hole forming step S3 is performed. In the through hole forming step S3, through holes are formed at predetermined positions where the through hole conductors 6, 7, and 8 are to be formed later. After the through hole is formed in the sheet, an internal electrode printing step S4 is performed. In this step, the respective electrode patterns and through-hole conductor patterns are printed on the upper surfaces of the piezoelectric layers 10 to 70 before cutting. At this time, for each of the piezoelectric layers 10 to 70, the external electrode layer 11, the relay electrode layer 21, the first internal electrode layer 31, the first ground electrode layer 41, the second internal electrode layer 51, and the second ground electrode layer 61 and patterns of through-hole conductors 6, 7, and 8 are formed. When the electrode pattern is formed, the stacking / pressing step S5 is performed. In this step, the piezoelectric layers 10, 20, 30, 40, 50, 60, and 70 before cutting are stacked in this order from the top and pressed. As a result, a laminate 80 as shown in FIG. 7 is obtained. After pressing, a binder removal / firing step S6 is performed. In this step, the laminate 80 is subjected to binder removal processing and firing processing.

  After firing the laminate 80, a polishing step S7 is performed. In the polishing step S7, the resonance of the longitudinal vibration mode and the resonance frequency of the bending vibration mode are matched by polishing the thickness adjusting layers LY1 and LY2. Specifically, the piezoelectric layer 10 or the piezoelectric layer 70 is polished. After polishing, a surface electrode printing step S8 is performed. In this step, the first external electrode 12 for electrically connecting the through-hole conductors 6, 7, 8 formed on the piezoelectric layer 10 and exposed on the upper surface of the piezoelectric layer 10 to an external circuit, the ground A pattern of the external electrode 13 and the second external electrode 14 is printed and printed on the upper surface of the piezoelectric layer 10. Next, a polarization step S9 is performed. In this polarization step S9, a polarization process is performed in order to make the polarities of the piezoelectric materials uniform. Thereafter, an individual product cutting step S <b> 10 for cutting the laminated body 80 for each element body 2 is performed.

  The individually cut element bodies 2 are put into a barrel polishing machine, and a barrel polishing step S11 is performed. After polishing, a chip bonding step S12 is performed in which the friction chips 4A and 4B are bonded to the second main surface 2b of the element body 2. Finally, an electrical property inspection step S13 and an appearance inspection step S14 for inspecting electrical properties are performed, and the manufacturing process shown in FIG. 6 is completed.

  Next, functions and effects of the multilayer piezoelectric element 1 configured as described above will be described.

  In the multilayer piezoelectric element 1 according to the present embodiment, the first through-hole conductor 6 in the element body 2 that electrically connects the first external electrode 12, the first electrode 32, and the fourth electrode 52, and the second external electrode The second through-hole conductor 8 in the element body 2 that electrically connects the electrode 14, the second electrode 34, and the third electrode 54, and the element that electrically connects the ground external electrode 13 and the ground electrodes 43, 63 to each other. The ground through-hole conductors 7 in the body 2 are arranged at the center position in the longitudinal direction of the element body 2 and are arranged in the width direction of the element body 2. As described above, since the electrodes are electrically connected by the through-hole conductors 6, 7, and 8 formed in the element body 2, it is possible to design without considering contact with other components. In addition, the size of the component can be reduced as compared with the case where the side electrodes are provided as in the conventional multilayer piezoelectric element. In addition, since the through-hole conductors 6, 7, and 8 that connect the electrodes are provided inside the element body 2, it is possible to prevent the influence of the surrounding environment, thereby improving the reliability. it can. In addition, when there are side electrodes on the outside, a step of forming the side electrodes for each element body after forming the laminate 80 and cutting each element body at the time of manufacture is added. By providing the through-hole conductors 6, 7, and 8 in the body 2, it is possible to omit the side electrode forming step after cutting the multilayer body 80.

  Here, as described above, the first electrode 32 and the fourth electrode 52 forming a diagonal positional relationship with respect to the center position in the longitudinal direction of the element body 2 with the ground electrode 43 interposed therebetween are electrically connected. Since the second electrode 34 and the third electrode 54 having the same positional relationship are electrically connected, the laminated piezoelectric element 1 has a longitudinal position with the center position of the element body 2 (the position of the center line CL) as a node. Although longitudinal vibration and bending vibration in the thickness direction are generated, the through-hole conductors 6, 7, and 8 are formed at the center position as a node in the multilayer piezoelectric element 1 according to the present embodiment. The stress acting on 6, 7, and 8 can be relaxed, and the reliability can be improved. Further, the structure around the element body portion provided with the through-hole conductor is softened, but by providing a plurality of through-hole conductors 6, 7, 8 at the center position in the longitudinal direction of the element body 2, the structure near the center position of the element body 2 is provided. The structure becomes soft and easily deformed. Specifically, as shown in FIG. 8, as compared to the displacement of the conventional multilayer piezoelectric element P in which the through-hole conductor is not formed at the center position in the longitudinal direction (indicated by displacement DP2 in the figure), The displacement (indicated by the displacement DP1 in the figure) of the multilayer piezoelectric element 1 of the present embodiment is increased. As a result, the displacement during driving can be increased without increasing the internal stress acting on the element body 2, and the performance can be improved. As described above, the multilayer piezoelectric element 1 can be miniaturized and the reliability and performance can be improved.

[Second Embodiment]
FIG. 9 is a developed perspective view of the element body 102 of the multilayer piezoelectric element according to the second embodiment of the present invention, and corresponds to FIG. The multilayer piezoelectric element according to the second embodiment of the present invention is different from the multilayer piezoelectric element 1 according to the first embodiment in that it differs from the external electrode layer 11 formed on the upper surface of the piezoelectric layer 10 of the element body 2. This is the point that the patterned external electrode layer 111 is formed.

  Specifically, as shown in FIG. 9, the external electrode layer 111 of the multilayer piezoelectric element according to the second embodiment includes a first external electrode 112, a ground external electrode 113, and a second external electrode 114. Has been. The ground external electrode 113 is formed in a rectangular shape at the center position in the longitudinal direction of the element body 102 (that is, the piezoelectric layer 10) and in the center position in the width direction. The first external electrode 112 is drawn out from the one end 10c of the piezoelectric layer 10 in a rectangular shape at a position that is 1/6 of the entire length in the longitudinal direction, and is drawn out in a substantially L shape from the connection electrode portion 112a. The relay electrode portion 112b is provided. The end portion of the relay electrode portion 112b extends to the center position in the longitudinal direction of the piezoelectric layer 10 so as to be adjacent to the ground external electrode 113 in the width direction. The relay electrode portion 112b is electrically connected to the first through-hole conductor 6, and the connection electrode portion 112a is connected to a voltage output terminal of an external device. The second external electrode 114 includes a connection electrode portion 114a formed in a rectangular shape at a position 1/6 of the entire length in the longitudinal direction from the other end 10d of the piezoelectric layer 10, and a substantially L-shape from the connection electrode portion 114a. The relay electrode portion 114b is drawn out. The end portion of the relay electrode portion 114b extends to the center position in the longitudinal direction of the piezoelectric layer 10 so as to be adjacent to the ground external electrode 113 in the width direction. The relay electrode portion 114b is electrically connected to the second through-hole conductor 8, and the connection electrode portion 114a is connected to a voltage output terminal of an external device.

  According to the multilayered piezoelectric element according to the second embodiment, of the first external electrode 112 and the second external electrode 114, the connection electrode portions 112a and 114a to which the terminals of the external device are connected are vibrated during vibration. It is formed at the position of 1/6 of the entire length in the longitudinal direction from the end of the element body 102 to be a node. Therefore, it is possible to prevent the multilayer electronic element from being detached from the terminal of the external device by vibration, and to improve the reliability of the component.

[Third embodiment]
FIG. 10 is an exploded perspective view of the element body 202 of the multilayer piezoelectric element according to the third embodiment of the present invention, and corresponds to FIG. 11 is a cross-sectional view taken along line XI-XI shown in FIG. The multilayer piezoelectric element according to the third embodiment of the present invention is different from the multilayer piezoelectric element 1 according to the first embodiment in that it differs from the external electrode layer 11 formed on the upper surface of the piezoelectric layer 10 of the element body 2. The pattern is that the external electrode layer 211 of the pattern is formed, and a plurality of through-hole conductors are formed for one electrode, and the formation positions of the through-hole conductors are shifted for each piezoelectric layer.

  As shown in FIG. 10, the external electrode layer 211 of the multilayer piezoelectric element according to the third embodiment includes a first external electrode 212, a ground external electrode 213, and a second external electrode 214. The first external electrode 212 is formed in a rectangular shape on one end side in the width direction and connected to the voltage output terminal of the external device, and the second external electrode 214 is formed in a rectangular shape on the other end side in the width direction. At the same time, it is connected to the voltage output terminal of the external device. The ground external electrode 213 is formed in a substantially I shape so as to extend in the longitudinal direction so as to pass between the first external electrode 212 and the second external electrode 214 at the center position in the width direction. That is, the ground external electrode 213 includes a rectangular contact portion 213a and a contact portion 213b at both ends in the longitudinal direction, and a connection portion 213c that connects the contact portions 213a and 213b. The first relay electrode 222, the ground relay electrode 223, and the second relay electrode 224 of the relay electrode layer 221 formed on the piezoelectric layer 20 are formed in the same shape and are equally spaced in the width direction of the element body 202. It is arranged. Accordingly, the shapes of the first relay electrodes 42 and 62, the relay electrode portions 32b and 52b, the second relay electrodes 44 and 64, and the relay electrode portions 34b and 54b are wider than those in the first embodiment. The shapes of the center positions in the longitudinal direction of the ground relay electrodes 33 and 53 and the ground electrodes 43 and 63 are narrower than those in the first embodiment.

  According to the multilayer piezoelectric element according to the third embodiment, the ground external electrode 213 has a shape extending in the longitudinal direction of the element body 202. Therefore, if the contact part 213a or the contact part 213b is used as a probe contact part in the polarization process at the time of manufacture, the probe connection point of the first external electrode 212 or the second external electrode 214 and the probe connection point of the ground external electrode 213 are used. The distance between can be increased. As a result, the reliability of contact of the probe during polarization can be improved, and the element can be miniaturized.

  Further, in the multilayer piezoelectric element according to the third embodiment, as shown in FIG. 11, four first through-hole conductors 206 </ b> A in which the first external electrode 212 and the first relay electrode 222 are provided on the piezoelectric layer 10. Is electrically connected. Four first through-hole conductors 206B to 206F are also formed on the piezoelectric layers 20 to 60 (206C is not shown). The first through-hole conductor 206B formed in the piezoelectric layer 20 adjacent to the piezoelectric layer 10 in the thickness direction is arranged in the width direction of the element body 202 so as not to overlap the first through-hole conductor 206A when viewed from the thickness direction. They are offset. As described above, the first through-hole conductors 206A to 206F have a staggered arrangement in which the positions in the width direction are shifted for each piezoelectric layer. The ground external electrode 213 and the ground relay electrode 223 are electrically connected by four ground through-hole conductors 207A provided on the piezoelectric layer 10. Four ground through-hole conductors 207B to 207F are also formed on the piezoelectric layers 20 to 60 (207C is not shown). The ground through-hole conductor 207B formed in the piezoelectric layer 20 adjacent to the piezoelectric layer 10 in the thickness direction is shifted in the width direction of the element body 202 so as not to overlap the ground through-hole conductor 207A when viewed from the thickness direction. Has been placed. Thus, the ground through-hole conductors 207A to 207F are arranged in a staggered arrangement in which the positions in the width direction are shifted for each piezoelectric layer. The second external electrode 214 and the second relay electrode 224 are electrically connected by four second through-hole conductors 208 </ b> A provided on the piezoelectric layer 10. Four second through-hole conductors 208B to 208F are also formed on the piezoelectric layers 20 to 60, respectively (208C is not shown). The second through-hole conductor 208B formed in the piezoelectric layer 20 adjacent to the piezoelectric layer 10 in the thickness direction is arranged in the width direction of the element body 202 so as not to overlap the second through-hole conductor 208A when viewed from the thickness direction. They are offset. As described above, the second through-hole conductors 208A to 208F are in a staggered arrangement in which the positions in the width direction are shifted for each piezoelectric layer. In the present embodiment, a through hole is formed only in each piezoelectric layer, and no through hole is formed in each electrode.

  As described above, in the multilayer piezoelectric element according to the third embodiment, when the through-hole conductors are arranged in the same position as viewed from the thickness direction by shifting the positions of the through-hole conductors for each piezoelectric layer. Compared to the above, stress concentration and poor connection can be reduced.

[Fourth embodiment]
FIG. 12 is a developed perspective view of the element body 302 of the multilayer piezoelectric element according to the fourth embodiment of the present invention, and corresponds to FIG. The multilayer piezoelectric element according to the fourth embodiment of the present invention is different from the multilayer piezoelectric element according to the third embodiment in that the pattern is different from that of the external electrode layer 211 formed on the upper surface of the piezoelectric layer 10 of the element body 2. The external electrode layer 311 is formed.

  Specifically, as shown in FIG. 12, the external electrode layer 311 of the multilayer piezoelectric element according to the fourth embodiment includes a first external electrode 312, a ground external electrode 313, and a second external electrode 314. Has been. The first external electrode 312 is formed in a U-shape that opens toward the inner periphery on one end side in the width direction and is connected to the voltage output terminal of the external device, and the second external electrode 314 is the other end in the width direction. It is formed in a U-shape that opens toward the inner periphery on the side, and is connected to the voltage output terminal of the external device. The ground external electrode 313 is formed in a rectangular shape at the center in the width direction. The first external electrode 312 protrudes toward the inner peripheral side of the piezoelectric layer 10 at both ends of the connecting portion 312c and the connecting portion 312c extending toward both ends in the longitudinal direction at the center position in the longitudinal direction of the element body 302. Rectangular contact portions 312a and 312b are provided. The second external electrode 314 has a connection portion 314c extending toward both ends in the longitudinal direction at the center position in the longitudinal direction of the element body 302, and toward the inner peripheral side of the piezoelectric layer 10 at both ends of the connection portion 314c. A protruding rectangular contact portion 314a, 314b is provided.

  According to the multilayer piezoelectric element according to the fourth embodiment, the first external electrode 312 and the second external electrode 314 have a shape extending in the longitudinal direction of the element body 202. Therefore, if the contact portions 312a and 314a or the contact portions 312b and 314b are used as the probe contact portions in the polarization process at the time of manufacture, the probe connection point of the first external electrode 312 or the second external electrode 314 and the ground external electrode 313 are used. The distance between the probe connection points can be increased. As a result, the reliability of contact of the probe during polarization can be improved, and the element can be miniaturized.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not necessarily limited to embodiment mentioned above, A various change is possible in the range which does not deviate from the summary.

  For example, in the above-described embodiment, the semi-cylindrical friction tip is attached to the second main surface side of the element body. However, instead of this, a cylindrical friction tip may be attached. Alternatively, a groove having a semicircular cross section may be formed on the second main surface side, and a cylindrical friction tip may be embedded therein, and only a semicircle portion of the friction tip may protrude from the element body. Furthermore, as shown in FIG. 13 (a), the friction tip 4C may be attached to the end face in the longitudinal direction, or as shown in FIG. 13 (b), a cylindrical friction tip 4D may be attached. Alternatively, a cylindrical friction tip may be filled by forming a semicircular groove in the end face in the longitudinal direction of the element body.

  In the example shown in FIG. 11, the through-hole conductors between the electrodes are arranged in a staggered arrangement, but a plurality of linear through-hole conductors shown in the first embodiment can be formed in the width direction with respect to each electrode. Good.

  DESCRIPTION OF SYMBOLS 1 ... Laminated piezoelectric element 2,102,202,302 ... Element body, 2a ... 1st main surface, 2b ... 2nd main surface, 2c ... One end, 2d ... Other end, 6,206A-206F ... First through Hall conductor, 7, 207A to 207F ... ground through hole, 8,208A to 208F ... second through hole conductor, 10, 20, 30, 40, 50, 60, 70 ... piezoelectric layer, 11, 111, 211, 311 ... external electrode layer, 12, 112, 212, 312 ... first external electrode, 13, 113, 213, 313 ... ground external electrode, 14, 114, 214, 314 ... second external electrode, 31 ... first internal electrode layer 32 ... 1st electrode, 32a ... Electrode part, 34 ... 2nd electrode, 34a ... Electrode part, 41 ... 1st ground electrode layer (ground electrode layer), 43 ... Ground electrode, 51 ... 2nd internal electrode layer, 52 ... fourth electrode, 2a ... electrode portion, 54 ... third electrode, 54a ... electrode portion.

Claims (2)

A rectangular parallelepiped element formed by laminating a plurality of piezoelectric layers and having first and second main surfaces;
A first electrode including an electrode portion disposed in the element body so as to oppose the first and second main surfaces and disposed on one end side of a center position in a longitudinal direction of the element body; and from the center position And a first internal electrode layer including a second electrode that is electrically insulated from the first electrode and includes an electrode portion disposed on the other end side,
Arranged in the element body so as to face the electrode part of the first electrode and the electrode part of the second electrode of the first internal electrode layer across the piezoelectric layer on the second main surface side. A ground electrode layer having a ground electrode;
A third electrode including an electrode portion disposed in the element body so as to face the ground electrode layer across the piezoelectric layer on the second main surface side, and disposed on the one end side with respect to the central position; And a second internal electrode layer including a fourth electrode that is electrically insulated from the third electrode portion and includes an electrode portion disposed on the other end side than the center position,
An external electrode layer formed on the first main surface, each having an electrically insulated first external electrode, a second external electrode, and a ground external electrode;
A first through-hole conductor that extends in the thickness direction, which is a direction in which the piezoelectric layers are laminated, in the element body and electrically connects the first external electrode, the first electrode, and the fourth electrode;
A second through-hole conductor that extends in the thickness direction in the element body and electrically connects the second external electrode, the second electrode, and the third electrode;
A ground through-hole conductor extending in the thickness direction in the element body and electrically connecting the ground external electrode and the ground electrodes;
The first through-hole conductor, the second through-hole conductor, and the ground through-hole conductor are arranged at the center position and are arranged in the width direction of the element body,
A multilayer piezoelectric element characterized by causing longitudinal vibration in the longitudinal direction and bending vibration in the thickness direction.   The first through-hole conductor, the second through-hole conductor, and the ground through-hole conductor formed in one piezoelectric layer are the first through-hole formed in the piezoelectric layer adjacent in the thickness direction. 2. The multilayer piezoelectric element according to claim 1, wherein the laminated piezoelectric element does not overlap with the conductor, the second through-hole conductor, and the ground through-hole conductor as viewed from the thickness direction.

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