JP2010103977A - Vibrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibrator in which stripping of a laminated piezoelectric element from a supporting plate during fall of the vibrator is suppressed. <P>SOLUTION: A principal plane of a laminate 17 at the side of a supporting plate 14 and the supporting plate 14 are bonded by a bottom surface side adhesive layer 15a, an exposed surface of an external electrode 13b and the supporting plate 14 are bonded by a side surface side adhesive layer 15b, and a height (h) of the side surface side adhesive layer 15b from the supporting plate 14 is set to be equal to or more than a height of the principal plane of the laminate 17 at the side of the supporting plate 14 and to be less than or equal to a 1/2 thickness (t) of the laminate 17. Thus, it is made possible to resist to tensile stress between a laminated piezoelectric element 10, 16 and the supporting plate 14 that is generated at a moment of landing in a fall test, and the stripping of laminated piezoelectric element 10, 16 from the supporting plate 14 during fall of the vibrator is suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vibrating body, and more particularly to a vibrating body using a bimorph type or unimorph type laminated piezoelectric element used in a flat speaker device for a computer, a mobile phone or a small terminal device.

  A conventional multilayer piezoelectric element is formed by alternately laminating piezoelectric layers and internal electrode layers, and a pair of rectangular main surfaces formed in the direction of stacking the piezoelectric layers and the internal electrode layers in the length direction. It has a plate-like laminate having a pair of side surfaces drawn alternately, and an external electrode provided on the side of the laminate.

  As shown in FIG. 6, the conventional vibrating body is manufactured as a bimorph type or unimorph type vibrating body by bonding one main surface of the multilayer piezoelectric element as described above to a support plate using an adhesive. (For example, refer to Patent Document 1).

  As shown in FIG. 6A, the conventional vibrating body is configured by joining laminated piezoelectric elements 30 and 36 to the upper and lower surfaces of the support plate 34 using only the bottom surface side adhesive layer 35.

  That is, the stacked piezoelectric elements 30 and 36 are configured by stacking seven layers of piezoelectric bodies 31 and six layers of internal electrode layers 32 alternately, and having a surface electrode layer 33a on the upper and lower surfaces, and the stacked body. And a pair of external electrodes 33b respectively provided at both ends in the longitudinal direction. The stacked piezoelectric elements 30 and 36 are plate-shaped, and the upper and lower main surfaces are rectangular, and a pair of side surfaces in which the internal electrode layers 32 are alternately drawn are formed in the length direction of the stacked body. External electrodes 33b are respectively formed on the pair of side surfaces.

  The six internal electrode layers 32 and the two surface electrode layers 33a are alternately formed as electrode layers, and each of the pair of external electrodes 33b has three layers of internal electrode layers 32 and one layer on the side surface of the laminate. The surface electrode layer 33a is electrically connected.

  Usually, an adhesive is applied to the support plate 34, and the laminated piezoelectric elements 30 and 36 are pressed against the adhesive layer to join them. As shown in FIG. 6B, a wide adhesive layer is formed. Even if the laminated piezoelectric elements 30 and 36 are pressed against the adhesive layer and joined by the bottom side adhesive layer 35 and the side side adhesive layer 39, the side side adhesive located outside the laminated body. The height h of the layer 39 from the support plate 34 is lower than the main surface on the support plate 34 side of the laminate. In FIG. 6B, the bottom surface side adhesive layer 35 and the side surface side adhesive layer 39 are shown as separate bodies for convenience. However, in the case of the same material, they are integrated.

  Also, conventionally, a vibrating body in which unevenness is formed on the support plate and the bonding area between the laminated piezoelectric element and the support plate is increased by an adhesive, or a through hole is formed in the support plate, and the adhesive is placed in the through hole. In addition, a vibrating body is known in which the bonding strength between the laminated piezoelectric element and the support plate is improved (see Patent Document 2).

JP 2007-329431 A JP-A-8-293631

  In the vibrating body of Patent Document 1, one main surface of the laminated body is bonded to the support plate 34 only by the bottom adhesive layer 35. In such a vibrating body, the supporting plate of the laminated piezoelectric elements 30 and 36 is used. There was a problem that peeling from 34 tends to occur.

  That is, when the vibrating body falls on the floor or the like, the moment of arrival of the vibrating body causes the laminated piezoelectric element 36 located on the lower surface side of the support plate 34 to move in the direction of gravity corresponding to the weight of the laminated piezoelectric element 36. When a strong force is exerted and this force exceeds the bonding force by the bottom surface side adhesive layer 35, there is a problem that the laminated piezoelectric element 36 is easily peeled off from the support plate 34.

  Moreover, in patent document 2, an unevenness | corrugation or a through-hole is formed in a support plate, and only one main surface of a laminated body is joined to a support plate with an adhesive via an unevenness | corrugation and a through-hole, and the joining strength by a tension test However, there is a problem that the laminated piezoelectric element is still easily peeled off from the support plate due to an impact such as dropping of the vibrating body.

  An object of this invention is to provide the vibrating body which can suppress peeling from the support plate of a lamination type piezoelectric element at the time of fall.

  The vibrating body of the present invention is formed by alternately laminating piezoelectric layers and internal electrode layers, and has a pair of rectangular main surfaces and a pair of side surfaces provided at both ends in the longitudinal direction of the main surfaces. A laminated piezoelectric element comprising: a plate-like laminate; and a pair of external electrodes provided on the pair of side surfaces of the laminate and electrically connected alternately to the internal electrode layers; A vibrating body comprising a support plate bonded to the main surface side of the piezoelectric element, the main surface on the support plate side of the laminate and the support plate are bonded with a bottom surface side adhesive layer, and The exposed surface of the external electrode and the support plate are joined by a side adhesive layer, and the height of the side adhesive layer from the support plate is from the support plate to the support of the laminate. It is not less than the height to the main surface on the plate side and not more than 1/2 of the thickness of the laminate.

  When the laminated piezoelectric element is bonded to the support plate using only the bottom surface side adhesive layer, the drop test results in the laminated piezoelectric element positioned in the falling direction of the support plate at the moment of landing according to the weight of the laminated piezoelectric element. When a strong force in the direction of gravity is applied and this force exceeds the bonding force of the bottom surface side adhesive layer, peeling from the support plate of the laminated piezoelectric element is likely to occur. By bonding the laminated piezoelectric element to the support plate not only by the agent layer but also by the side surface side adhesive layer whose height from the support plate is not less than the height of the main surface on the support plate side of the laminate, in other words, At the moment when the external electrode of the laminated piezoelectric element is firmly joined to the support plate by the side adhesive layer whose height from the support plate is equal to or higher than the height of the main surface of the laminate, and landing during the drop test Withstand the tensile stress generated between the laminated piezoelectric element and the support plate Can, it is possible to suppress separation from the support plate of the laminated piezoelectric element at the time of drop of the vibrator.

  Furthermore, since the height of the side adhesive layer from the support plate is ½ or less of the thickness of the multilayer piezoelectric element, peeling of the external electrode from the multilayer body can be effectively suppressed. That is, when the height of the side adhesive layer from the support plate is high, the multilayer piezoelectric element is firmly bonded to the support plate, and peeling of the multilayer piezoelectric element from the support plate in the drop test can be suppressed. On the other hand, the thermal expansion coefficient of the side adhesive layer is larger than that of the piezoelectric layer, the internal electrode layer, and the external electrode of the multilayer piezoelectric element. Tensile stress in the length direction of the main surface is generated between the side surface and the external electrode to which the side surface side adhesive layer is bonded, and it becomes easy to peel between them. When the vertical position is ½ or less of the thickness of the multilayer piezoelectric element, the tensile stress in the length direction between the side surface of the multilayer body and the external electrode can be reduced, and the external electrode is peeled from the multilayer body. Can be effectively suppressed.

  The vibrating body according to the present invention is characterized in that the number of stacked piezoelectric layers of the stacked piezoelectric element is 7 or more.

  In order to drive the multilayer piezoelectric element with high displacement and low voltage, it is conceivable to increase the number of piezoelectric layers, but if the number of piezoelectric layers is increased to 7 or more, the weight of the multilayer piezoelectric element increases. Since it becomes heavier and the support plate and the laminated piezoelectric element are easily peeled in a drop test, the present invention can be used particularly suitably.

  The vibrating body according to the present invention is characterized in that the support plate is made of a metal or an alloy, and a conductive layer for electrically connecting the external electrode and the support plate is formed on the upper surface of the side-surface adhesive layer. And

  According to the vibrating body of the present invention, when the conductor layer is formed on the upper surface of the side adhesive layer, the thermal expansion coefficient of the adhesive of the side adhesive layer and the metal component of the conductor layer is Since it is larger than the thermal expansion coefficient of the piezoelectric layer, a larger tensile stress is applied between the side surface of the laminate and the external electrode, so that the present invention can be used particularly suitably.

  The vibrating body according to the present invention is characterized in that the bottom-side adhesive layer has a thickness of 1 μm or more. When the thickness of the bottom surface side adhesive layer is 1 μm or more, the laminated piezoelectric element and the support plate can be more firmly bonded. Therefore, the laminated piezoelectric element can be used even when the diaphragm receives a drop impact or the like. Peeling between the element and the support plate can be suppressed.

  Moreover, the vibrating body according to the present invention is characterized in that the laminate is barrel processed. In such a vibrating body, for example, by putting a plate-like laminate into a container enclosing media and abrasive powder and rotating barrel processing, 12 sides (corner portions) of the laminate, and these sides 8 corners created by crossing three of them are all rounded and polished, for example, the corners of the laminate have an R surface of 60 μm or more, and from the bottom adhesive layer to the side adhesive The continuity of the adhesive layer over the layers becomes good, and peeling of the multilayer piezoelectric element from the support plate when the vibrating body is dropped can be further suppressed.

  Moreover, the vibrating body of the present invention is characterized in that the thickness of the laminate is 0.7 mm or less. In the case of such a thin laminated piezoelectric element, not only the tensile stress applied to the external electrode is large, but also the stress applied to the laminated piezoelectric element due to dropping or the like is large, so that the present invention can be used more suitably.

  The vibrating body of the present invention bonds the laminated piezoelectric element to the support plate not only by the bottom surface side adhesive layer but also by the side surface side adhesive layer whose height from the support plate is equal to or higher than the height of the main surface of the laminate. As a result, the external electrode of the multilayer piezoelectric element is firmly bonded to the support plate, and can withstand the tensile stress between the multilayer piezoelectric element and the support plate that occurs at the moment of landing of the drop test, and vibration It is possible to suppress peeling of the multilayer piezoelectric element from the support plate when the body falls, and the height of the side adhesive layer from the support plate is ½ or less of the thickness of the multilayer piezoelectric element. Further, peeling of the external electrode from the laminate can be effectively suppressed, and a highly reliable vibrator can be obtained.

It is sectional drawing of the bimorph type vibrating body of this invention. It is a top view of the bimorph type oscillating body of the present invention. It is sectional drawing of the vibrating body of this invention which has a conductor layer on the surface of a side surface side adhesive layer. It is sectional drawing which shows the other form of the bimorph type vibrating body of this invention. (A) is sectional drawing which expands and shows the laminated piezoelectric element of FIG. 4, (b) is a top view of (a). 1 shows a conventional bimorph type vibrator, (a) is a cross-sectional view, (b) is a cross-sectional view when an adhesive layer is widely formed, and a laminated piezoelectric element is pressed against and bonded to the adhesive layer. It is.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a bimorph type vibrator of the present invention, and FIG. 2 is a plan view. In FIG. 2, hatched lines are shown for easy understanding.

  As shown in FIGS. 1 and 2, the bimorph type vibrating body of the present invention is configured by bonding laminated piezoelectric elements 10 and 16 to the upper and lower surfaces of a support plate 14 with an adhesive. Note that the present invention is not limited to the bimorph type multilayer piezoelectric element, and the effect of the present invention can be obtained even with a unimorph type in which the multilayer piezoelectric element is joined to one side of the support plate. In FIG. 1, the thickness of the multilayer piezoelectric elements 10 and 16 is enlarged for easy understanding.

  The laminated piezoelectric elements 10 and 16 are formed by alternately laminating seven piezoelectric layers 11 having a thickness of 10 to 60 μm and six internal electrode layers 12 and having surface electrode layers 13a on the upper and lower surfaces. 17 and a pair of external electrodes 13b respectively provided at both ends in the longitudinal direction of the laminate 17.

  The laminated body 17 is plate-shaped, and the upper and lower main surfaces are rectangular, and the longitudinal direction x of the main surface of the laminated body 17 has a pair of side surfaces from which the internal electrode layers 12 are alternately drawn. Yes. The rectangular main surface of the laminated body 17 desirably has a width of 5 mm or less and a length of 10 mm or more. In such a multilayer piezoelectric element, in particular, the displacement in the length direction x of the main surface increases, and a tensile stress in the length direction x of the main surface is generated between the side surface of the multilayer body 17 and the external electrode 13b. Since it becomes easy, this invention can be used suitably. The present invention can be suitably used when the rectangular main surface of the laminate 17 has a width of 5 mm or less and a length of 17 mm or more.

  Further, when the number of stacked piezoelectric layers 11 of the stacked body 17 is 7 or more, the weight of the stacked piezoelectric elements 10 and 16 becomes heavy, and therefore the support plate 14 and the stacked piezoelectric element 10 are used in the drop test. , 16 can be easily peeled off, so that the present invention can be used more suitably.

  The internal electrode layer 12 preferably contains a metal component composed of silver and palladium and a material component constituting the piezoelectric layer 11. By including the material component constituting the piezoelectric layer 11 in the internal electrode layer 12, it is possible to reduce stress due to a difference in thermal expansion between the piezoelectric layer 11 and the internal electrode layer 12, and a stacked piezoelectric element that does not have stacking faults 10, 16 can be obtained. The internal electrode layer 12 is not particularly limited to a metal component composed of silver and palladium, and is not limited to a material component constituting the piezoelectric layer 11 as a ceramic component. It may be.

  The surface electrode layer 13a and the external electrode 13b desirably contain a glass component in the metal component made of silver. By containing a glass component, it is possible to obtain a strong adhesion between the piezoelectric layer 11 and the internal electrode layer 12 and the surface electrode layer 13a or the external electrode 13b.

  External electrodes 13b are provided at both ends in the length direction x of the laminate 17 so as to cover from the side surface of the laminate 17 to the ends in the length direction x of the upper and lower main surfaces. In the multilayer piezoelectric elements 10 and 16, six internal electrode layers 12 and two surface electrode layers 13 a are alternately formed as electrode layers, and the pair of external electrodes 13 b are provided on the side surfaces facing the multilayer body 17. Three internal electrode layers 12 and three surface electrode layers 13a are electrically connected.

  In the vibrating body of the present invention, the main surface of the laminate 17 on the support plate 14 side and the support plate 14 are joined by the bottom surface side adhesive layer 15a, and a part of the exposed surface of the external electrode 13b and the support plate 14 are joined. Are joined by the side adhesive layer 15b. In other words, the side adhesive layer 15b is attached to the exposed surface of the external electrode 13b, and is also attached to the surface of the support plate 14 so that the skirt is widened. The side surface side adhesive layer 15b has a height h equal to or higher than the height of the main surface on the support plate 14 side of the laminate 17, and the height h of the side surface side adhesive layer 15b from the support plate 14 is equal to the laminate body. 17 or less of the thickness t of 17.

  In the present invention, not only the bottom surface side adhesive layer 15a but also the side surface side adhesive layer 15b whose height h from the support plate 14 is higher than the height of the main surface on the support plate 14 side of the laminate 17 is used for the drop test. A shear stress generated between the exposed surface of the external electrode 13b and the side adhesive layer 15b is generated with respect to the tensile stress generated between the laminated piezoelectric elements 10 and 16 and the support plate 14 generated at the time of landing. It can withstand and resist the peeling of the laminated piezoelectric elements 10 and 16 from the support plate 14.

  On the other hand, when the height h of the side adhesive layer 15b is lower than the height of the main surface of the laminated body 17, the gap between the laminated piezoelectric elements 10 and 16 and the support plate 14 that occurs at the time of landing in the drop test. The tensile stress of the laminated piezoelectric elements 10 and 16 from the support plate 14 can hardly be prevented.

  Further, when the height h of the side adhesive layer 15b from the support plate 14 is larger than ½ of the thickness t of the laminate 17, the multilayer piezoelectric elements 10 and 16, the support plate 14 and the side adhesive layer. Due to the difference in the thermal expansion coefficient of 15b, in a reliability test such as a temperature cycle or a high temperature and high humidity leaving test, the joint between the internal electrode layer 12 and the external electrode 13b of the laminate 17 is peeled off, and electrical connection cannot be obtained. The laminated piezoelectric elements 10 and 16 are not displaced and the vibrating body does not vibrate. However, as in the present invention, the height h of the side adhesive layer 15b from the support plate 14 is set to the laminated body. When the thickness t is equal to or less than ½ of the thickness t of 17, the peeling of the external electrode 13b from the side surface of the multilayer body 17 can be suppressed, and the internal electrode layer 12 and the external electrode 13b of the multilayer body 17 can be reliably bonded. Maintain a secure connection.

  The side adhesive layer 15b is continuous with the bottom adhesive layer 15a, and in the present invention, the adhesive layer between the portions of the pair of external electrodes 13b protruding toward the support plate 14 is used as the bottom adhesive layer 15a. In more detail, the adhesive layer positioned between the side surfaces of the laminate 17 is defined as the bottom surface side adhesive layer 15a, and the adhesive layer positioned outside the side surface layer is defined as the side surface side adhesive layer 15b.

  Further, in order to increase the bonding strength between the multilayer piezoelectric elements 10 and 16 and the support plate 14, the thickness of the bottom surface side adhesive layer 15a between the multilayer piezoelectric elements 10 and 16 and the support plate 14 is set to 1 μm or more. ing. Thus, when the thickness of the bottom surface side adhesive layer 15a is 1 μm or more, since the thermal expansion coefficient of the adhesive is large, it is particularly long between the laminate 17 and the external electrode 13b due to a temperature change cycle. Since the tensile / compressive stress in the length direction x is generated and the external electrode 13b is easily peeled off, the present invention can be used more suitably.

  In addition, a width-direction side adhesive layer 18 is also formed on the side surfaces in the width direction of the multilayer piezoelectric elements 10 and 16, and the height of the width-direction side adhesive layer 18 from the support plate 14 is also set to the laminate 17. The height of the main surface on the support plate 14 side is equal to or greater than 1/2 of the thickness t of the laminate 17. As a result, the side surfaces in the width direction of the multilayer piezoelectric elements 10 and 16 are also firmly bonded.

  As the adhesive for forming the bottom surface side adhesive layer 15a and the side surface side adhesive layer 15b, known ones such as epoxy resins, silicon resins, polyester resins and the like can be used. As a method for curing the resin used for the adhesive, the vibrating body can be produced by using any of thermosetting, photocuring, anaerobic curing, and the like.

  In the vibrating body of the present invention, the external electrode 13b is electrically connected to the electrode pattern formed on the insulating support plate 14 or the conductive support plate 14 itself, and a voltage is applied between the external electrodes 13b to form a laminated type. The piezoelectric element is driven. In addition, a voltage is applied to the multilayer piezoelectric element 10 and the multilayer piezoelectric element 16 so as to be displaced to the same side with respect to the support plate 14. Thereby, the bimorph type vibrator as shown in FIGS. 1 and 2 vibrates greatly.

  As shown in FIG. 3, the support plate 14 is made of a metal or an alloy, and a conductor layer 55 is formed on the upper surface of the side adhesive layer 15b to connect the one external electrode 13b and the support plate 14. ing. Thus, when the conductor layer 55 is formed on the upper surface of the side adhesive layer 15b, the thermal expansion coefficient of the adhesive of the side adhesive layer 15b and the metal of the conductor layer 55 is the same as that of the stacked piezoelectric elements 10 and 16. Since it is larger than the thermal expansion coefficient, a larger tensile stress is applied between the internal electrode layer 12 and the external electrode layer 13b of the multilayer piezoelectric elements 10 and 16, so that the present invention can be used more suitably.

  Next, the manufacturing method of the vibrating body of this invention is demonstrated.

  First, a binder, a dispersant, a plasticizer, and a solvent are kneaded with the piezoelectric material powder to prepare a slurry. As the piezoelectric material, any of lead-based and non-lead-based materials can be used.

  Next, the obtained slurry can be formed into a sheet shape to obtain a green sheet, and an internal electrode pattern is formed by printing an internal electrode paste on the green sheet, and a green sheet on which this electrode pattern is formed is desired Are laminated, and only the green sheet is laminated on the uppermost layer to produce a laminated molded body.

  Next, the laminated body 17 can be obtained by degreasing and firing the laminated molded body. The laminated body 17 processes the outer peripheral part as necessary, prints the paste of the surface electrode layer 13a on both main surfaces of the laminated body 17 in the lamination direction, and continues the length direction of the laminated body 17 The laminated piezoelectric elements 10 and 16 can be obtained by printing the paste of the external electrode 13b on both sides of x and baking the electrode at a predetermined temperature.

  Next, in order to impart piezoelectricity to the multilayer piezoelectric elements 10 and 16, a DC voltage is applied through the surface electrode layer 13a or the external electrode 13b to polarize the multilayer piezoelectric elements 10 and 16.

  Next, an adhesive is applied to the support plate 14, the laminated piezoelectric elements 10 and 16 are pressed onto the support plate 14, and then the height of the side adhesive layer is increased in order to increase the height of the external electrode 13 b. The adhesive can be overcoated on the side adhesive layer of the exposed surface with a brush or the like, and then the adhesive can be cured by irradiation with heat or ultraviolet rays to obtain the vibrator of the present invention.

  FIG. 4 shows another embodiment of the vibrating body of the present invention. In this vibrating body, the difference from FIG. 1 is that the laminated body 17 is manufactured by barrel processing as shown in FIG. It is.

  That is, the laminated body 17 has a plate shape, the upper and lower main surfaces are formed into a pseudo-rectangular shape whose outer peripheral portion is polished, and the internal electrode layers 12 are alternately drawn in the length direction x of the main surface of the laminated body 17. A pair of side surfaces.

  The laminated body 17 is, for example, 12 sides (corner portions) formed by the two main surfaces and the four side surfaces of the laminated body 17 by putting them in a container enclosing a medium and abrasive powder and carrying out a rotating barrel process. In addition, the eight corners formed by intersecting three of these sides are all rounded and polished, for example, the corners of the laminate 17 have an R surface (curvature radius) of 60 μm or more. The radius of curvature of the corner of the laminate 17 is desirably 80 μm or more.

  By subjecting the multilayer body to barrel processing, surface electrodes 13a are formed on both main surfaces of the multilayer body 17, and the external electrode 13b is formed on the side surface where the internal electrode layer 12 is exposed. The external electrode 13b and the surface electrode layer 13a can be reliably formed. That is, when the laminated body 17 is not barrel-processed, it is necessary to form an external electrode or a surface electrode layer at the corner formed by the main surface and the side surface, and the application amount of the electrode paste is reduced at the corner. However, in the present invention, the 12 sides and the 8 corners formed by the intersection of these 3 sides are all rounded, so that the rounded portions A large amount of electrode paste can be applied to the external electrode 13b, and the connection between the external electrode 13b and the surface electrode 13a can be reliably performed.

  The size of the R surface varies depending on the diameter of the medium used, the average particle size of the abrasive, and the processing time. For example, when the polishing time is 10 hours, the average particle diameter of the abrasive is fixed to 8 μm, and the media diameter is 4 mm and 2 mm, the radius of curvature of the corner ( The radius of the corner portion was 85 μm when a medium having a diameter of 2 mm was used. When the media diameter was 4 mm, the average particle size of the abrasive was fixed at 8 μm, and the polishing time was 5 Hr and 15 Hr, the corner radiuses were 100 μm and 140 μm, respectively. When the media diameter was 2 mm and the time was 5 hours, the corner radius was 60 μm.

The present invention can be suitably used when the thickness of the laminate 17 is 0.7 mm or less, particularly 0.55 mm or less. In the case of such a thin plate-shaped laminated piezoelectric element, not only the tensile stress applied to the external electrode is large, but also the stress applied to the element due to dropping or the like is large, so that the present invention can be used more suitably. When the area of the main surface of the laminated body 17 is 50 mm ² or more, the strength of the laminated body 17 is lowered and easily damaged, and therefore the present invention can be used more suitably. In addition, the area of the main surface of the laminated body 17 is represented by the product of the width defined by the distance between a pair of opposing side surfaces and the length defined by the distance between the other pair of side surfaces.

  The damage is caused by the generation of stress exceeding the strength of the porcelain. A PZT thin plate with low porcelain strength is considered to be easily damaged when barreled, and conventionally barrel processing has not been adopted. On the other hand, the multilayer piezoelectric element breaks due to a crack when it is dropped and may peel off from the support plate. However, the occurrence of cracking that causes cracking is constant in mass production. In addition, since it occurred at any of the 12 sides (corner portions) and the 8 corner portions where the surfaces of the laminate intersect, the laminated piezoelectric element can be removed in advance by removing all the parts that may cause grain loss. It is possible to suppress cracks and to prevent breakage.

In the barrel processing of ceramics, zirconia balls having high hardness are usually used as media. In the present invention, soft glass beads are used as media, and Al ₂ O ₃ is used as polishing powder. In addition, in order to increase the destructive force when colliding with the ceramic element, the media diameter and the particle size distribution of the abrasive powder employ a glass bead having a diameter of 2 mm or more, and the abrasive powder having an average particle diameter of 15.5 μm or less is used. In this way, a laminated piezoelectric element with rounded corners can be easily manufactured.

  Then, the laminated piezoelectric element 10 in which the surface electrode 13a and the external electrode 13b are formed on the laminated body 17 whose corners are rounded and polished is used as a bottom surface side adhesive layer 15a and a side surface side adhesive layer 15b as shown in FIG. As shown in FIG. 4, from the bottom surface side adhesive layer 15a to the side surface side adhesive layer 15b, the surface electrode 13a and the external electrode 13b are smoothly formed on the laminate 17. The continuity of the adhesive layer becomes favorable, and the peeling of the laminated piezoelectric elements 10 and 16 from the support plate 14 when the vibrating body is dropped can be further suppressed.

  A slurry was prepared by kneading a piezoelectric powder containing lead zirconate titanate (PZT) in which a part of Zr was substituted with Sb, a binder, a dispersant, a plasticizer, and a solvent by ball mill mixing for 24 hours. .

  Using the obtained slurry, a green sheet having a thickness of about 50 μm was prepared by a doctor blade method. An electrode paste containing Ag and Pd as an electrode material is applied to the green sheet in a predetermined shape by screen printing, and 6 or 12 layers of the green sheet coated with the electrode paste are laminated, and the uppermost layer is an electrode paste. A green sheet not coated with one layer was stacked and pressed to produce two types of laminated molded bodies having different numbers of layers. These laminated molded bodies were degreased in the air at 500 ° C. for 1 hour, and then fired in the air at 1100 ° C. for 3 hours to obtain a laminated sintered body.

  Next, both end portions in the length direction x of the obtained laminate 17 are cut by dicing, the tips of the internal electrode layers 12 are exposed on the side surfaces of the laminate, and electrode layers are formed on both main surfaces of the laminate 17. In order to form, an electrode paste containing Ag and glass as an electrode material is applied to the main surface of the laminate by screen printing, and then Ag and glass are contained as external electrode materials at both ends in the length direction x. The electrode paste to be applied was applied by a dip method and baked in the air at 700 ° C. for 10 minutes to produce the multilayer piezoelectric elements 10 and 16.

  The dimensions of the main surface of the produced laminate 17 were 3.5 mm wide and 26 mm long, the piezoelectric layer 11 was 40 μm thick, and the internal electrode layer 12 was 3 μm thick.

  Next, between the internal electrode layers 12 through the surface electrodes 13a of the multilayer piezoelectric elements 10 and 16, and between the internal electrode layer 12 and the surface electrode 13a, the multilayer piezoelectric elements 10 and 16 having seven layers and thirteen piezoelectric layers 11 are provided. Both were polarized by applying a voltage of 100 V for 2 minutes.

  Next, a support plate 14 of 42 alloy (made of alloy) having a thickness of 0.2 mm was prepared, an adhesive made of a thermosetting epoxy resin was applied to both main surfaces of the support plate 14, and the adhesive was applied. The laminated piezoelectric elements 10 and 16 are pressed against the plate 14, and further, the adhesive is repeatedly applied to the side adhesive layer on the exposed surface of the external electrode 13 b with a brush or the like, and bonded in air at 120 ° C. for 1 hour. The agent was cured, a conductor layer 55 was formed on the surface of the side adhesive layer, and the external electrode 13b and the support plate 14 were electrically joined to produce a bimorph type vibrator as shown in FIG. On the other hand, the application area of the adhesive is narrowed, the laminated piezoelectric elements 10 and 16 are pressed against this part, and the main surface of the laminated body is joined only by the bottom adhesive layer, and the comparison as shown in FIG. Example samples were prepared.

  The produced bimorph type vibrator was measured for electric capacity with an impedance analyzer and listed in Table 2. In addition, the produced bimorph type vibrator was subjected to a temperature cycle test in which a temperature cycle of −40 ° C. to 85 ° C. and a holding time of 30 minutes at each temperature was performed 100 times, and the capacitance decreased by 5% or more from the initial value. The results are shown in Table 2, with the number of defects / number of tests as the defect rate.

  Furthermore, the produced bimorph type vibrator was subjected to a high-temperature and high-humidity standing test for 1000 hours in an atmosphere at a temperature of 60 ° C. and a humidity of 90%. It is shown in Table 2 as the defect rate by the number of defects / number of tests.

  Further, the bonding strength between the support plate of the vibrating body and the laminated piezoelectric element was confirmed by a drop test. The test condition was that one end of the support plate of the vibrating body was fixed to a mounting member, this mounting member was fixed to a 100 g drop test jig, and dropped freely from a drop height of 100 cm to a drop point made of marble three times in total. The vibrating body is observed with a 40 × microscope, and peeling occurs between the multilayer piezoelectric element and the support plate, or cracks in the multilayer piezoelectric element are regarded as defective. Rate.

  From Tables 1 and 2, the bottom side adhesive layer and the side adhesive whose height from the support plate is not less than the height of the main surface on the support plate side of the laminate and not more than 1/2 of the thickness of the laminate. In the sample of the present invention in which the laminated piezoelectric element was bonded to the support plate in layers, the defect rate was low in the temperature cycle test, the high temperature and high humidity leaving test and the drop impact test, and good results were obtained.

  On the other hand, sample No. 1 in which the laminated piezoelectric element and the support plate were joined only by the bottom surface side adhesive layer. 1 (7-layer product), sample no. 9 (13-layer product) has a high defect rate in the temperature cycle test, the high-temperature and high-humidity test and the drop impact test, and the height of the side adhesive layer from the support plate is 1/2 of the thickness of the laminate. Sample no. 4, 5 (7-layer product), sample No. 12 and 13 (13-layer products), it can be seen that the defect rate increases as the height of the side surface side adhesive layer increases.

The laminate produced in Example 1 was barrel processed. The dimensions of the main surface of the laminate 17 are 3.5 mm in width and 26 mm in length, the main surface area is 91 mm ² , and the dimensions of the main surface of the laminate 17 are changed. A laminate 17 having a surface area was produced. The thickness of the laminate 17 is shown in Table 3.

  For barrel processing, a 3 L polyethylene pot was used, and a glass ball having a diameter of 2 mm was used as a medium. As an abrasive powder, an alumina abrasive (WA) having an average particle size of 8 μm is used. A pot is filled with media, a laminate 17, an abrasive, and pure water as a solvent, and mixed for 6 to 40 hours. processed. In addition, as a sample which is not barrel processed, the sample Nos. 6-8 are shown in Tables 3 and 4. 17, 19, and 21.

  After the barrel processing of the laminate 17, the attached abrasive was removed by running water ultrasonic cleaning. The radius of eight sides (corner portions) formed by both main surfaces and the four side surfaces of the laminate 17 was measured, and the average of these was listed in Table 3 as the corner radius. Earl was obtained by measuring the corner with a three-dimensional shape measuring instrument (measurement scope: manufactured by Nissho Precision Optical Co., Ltd.). In addition, the control of Earl was adjusted by barrel processing time.

  In order to form surface electrode layers on both main surfaces of the laminate 17, an electrode paste containing Ag and glass as an electrode material is applied to the main surface of the laminate by screen printing, and then both ends in the length direction x. An electrode paste containing Ag and glass as an external electrode material is applied to the part by a dip method and baked in the atmosphere at 700 ° C. for 10 minutes, and the surface electrode layer and the external electrode are superimposed on the R surface of the laminate. Multilayer piezoelectric elements 10 and 16 as shown in FIG.

  In addition, for the laminated piezoelectric elements 10 and 16 subjected to barrel processing, the electrode thickness of the external electrode on the side surface of the laminate and the electrode thickness at the corner of the laminate (the thickness of the external electrode, the thickness of the surface electrode, or the external The thickness of the overlapping portion of the electrode and the surface electrode) was observed in a cross-section, and the electrode thickness at the corner of the laminate was 1/2 or more of the thickness of the external electrode on the side surface of the laminate, and had a sufficient thickness. In addition, the electrode thickness at the corner of the laminated body subjected to barrel processing was sufficient, and the electrical connectivity between the surface electrode layer and the external electrode was good.

  Next, polarization was performed by applying a voltage of 100 V for 2 minutes between the internal electrode layers 12 and between the internal electrode layers 12 and the surface electrodes 13a through the surface electrodes 13a of the multilayer piezoelectric elements 10 and 16.

  Next, a support plate 14 of 42 alloy (made of alloy) having a thickness of 0.2 mm was prepared, an adhesive made of a thermosetting epoxy resin was applied to both main surfaces of the support plate 14, and the adhesive was applied. The laminated piezoelectric elements 10 and 16 are pressed against the plate 14, and further, the adhesive is repeatedly applied to the side adhesive layer on the exposed surface of the external electrode 13 b with a brush or the like, and bonded in air at 120 ° C. for 1 hour. The adhesive was cured, a conductor layer 55 was formed on the surface of the side adhesive layer, and the external electrode 13b and the support plate 14 were electrically joined to produce a bimorph type vibrator as shown in FIG. . The height h of the side adhesive layer and the thickness of the bottom adhesive layer were measured and listed in Table 3. The height h of the side adhesive layer is the height from the support plate, and is described as a ratio to the thickness t of the laminate.

  The electrostatic capacity of these bimorph type vibrators was measured with an impedance analyzer and listed in Table 4. About the produced bimorph type | mold vibrator, the temperature cycle test and the high temperature, high humidity leaving test were done like Example 1, and the defect rate was described in Table 4.

  Further, the bonding strength between the support plate of the vibrating body and the laminated piezoelectric element was confirmed by a drop test. The test condition was that one end of the support plate of the vibrating body was fixed to a mounting member, this mounting member was fixed to a 100 g drop test jig, and dropped freely from a drop height of 100 cm to a drop point made of marble three times in total. The vibrating body is observed with a 40 × microscope, and peeling occurs between the multilayer piezoelectric element and the support plate, or cracks in the multilayer piezoelectric element are regarded as defective. It was set as a rate and it described in Table 4. Further, a drop test similar to the above was performed except that the drop height was 150 cm, and the results are shown in the column of the advanced drop test in Table 4.

  After the high drop test, the defective vibrating body was observed with a 40 × microscope. As a result, almost no cracks were observed in the multilayer piezoelectric element in the barrel-processed sample, and peeling occurred between the multilayer piezoelectric element and the support plate. In most cases, defects occur and become defective. On the other hand, in the samples that were not barrel-processed, cracks occurred in the multilayer piezoelectric elements of most samples.

  From these Tables 3 and 4, when the laminated body is barrel processed, the continuity of the adhesive layer from the bottom surface side adhesive layer to the side surface side adhesive layer becomes good as shown in FIG. It can be seen that peeling of the laminated piezoelectric element from the support plate at the time can be further suppressed. Furthermore, it can be seen that by performing barrel processing, the grain breakage in the multilayer piezoelectric element can be suppressed, the generation of cracks can be suppressed, and the defect rate in the advanced drop test can be reduced.

DESCRIPTION OF SYMBOLS 10, 16 ... Laminated piezoelectric element 11 ... Piezoelectric layer 12 ... Internal electrode layer 13a ... Surface electrode layer 13b ... External electrode 14 ... Support plate 15a ... Bottom side adhesion Adhesive layer 15b ... Side-side adhesive layer x ... Main surface length direction h ... Side-side adhesive layer height t from support plate ... Laminate thickness

Claims (7)

  Piezoelectric layers and internal electrode layers are alternately laminated, and a plate-like laminate having a pair of rectangular main surfaces and a pair of side surfaces provided at both ends in the longitudinal direction of the main surfaces; A laminated piezoelectric element comprising a pair of external electrodes provided on the pair of side surfaces of the laminated body and alternately electrically connected to the internal electrode layers; and the main surface side of the laminated piezoelectric element includes: A vibrating body comprising a bonded support plate, wherein the main surface on the support plate side of the laminate and the support plate are bonded with a bottom surface side adhesive layer, and the exposed surface of the external electrode and the A support plate is joined with a side adhesive layer, and the height of the side adhesive layer from the support plate is from the support plate to the main surface of the laminate on the support plate side. A vibrator having a height of not less than 1/2 and not more than 1/2 of the thickness of the laminate.   The vibrator according to claim 1, wherein the number of stacked piezoelectric layers of the stacked piezoelectric element is 7 or more.   The said support plate consists of a metal or an alloy, and the conductor layer for electrically connecting the said external electrode and the said support plate is formed in the upper surface of the said side surface side adhesive bond layer. The vibrator described in 1.   The vibrating body according to any one of claims 1 to 3, wherein the bottom surface side adhesive layer has a thickness of 1 µm or more.   The vibrating body according to claim 1, wherein the laminated body is barrel processed.   6. The vibrating body according to claim 1, wherein a corner portion of the laminated body has an R surface of 60 μm or more.   The vibrating body according to any one of claims 1 to 6, wherein the thickness of the laminated body is 0.7 mm or less.

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