Piezoelectric ceramic laminate

Abstract

To provide a piezoelectric ceramic laminate capable of securing insulation while increasing an area of an internal electrode.SOLUTION: A piezoelectric ceramic laminate 10 includes a laminate body 20 in which a plurality of piezoelectric ceramic layers 50 and a plurality of plate-shaped internal electrodes 60 are alternately laminated. The multilayer body 20 has a hexahedral shape, and includes two bottom surfaces 25, 26 located at both ends in a stacking direction, a first side surface 21 and a second side surface 22 arranged back-to-back, and a third side surface 23 and a fourth side surface 24 arranged back-to-back. A first internal electrode 61 includes lead-out portions 61B connected to an external electrode 30. The lead-out portion 61B is exposed from the first side surface 21 of the laminate body 20. Side edge portions 61E, 61F of the first internal electrode 61 exposed from the third side surface 23 and the fourth side surface 24 are covered with an insulating coating portion 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to piezoelectric ceramic laminates. [Background technology]

[0002] The piezoelectric element disclosed in Patent Document 1 has a configuration in which piezoelectric layers and internal electrodes are alternately stacked. The internal electrodes have lead portions that are connected to external electrodes. All edges of the internal electrodes, except for the lead portions, are enclosed by the piezoelectric layers and are not exposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-12007 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for smaller piezoelectric elements. However, in the piezoelectric element of Patent Document 1, if the size is reduced without changing the dimensional ratio, the amount of recession of the internal electrodes (the distance from the outer edge of the internal electrodes to the outer surface of the piezoelectric element) can be maintained, but the area of ​​the internal electrodes will be reduced. On the other hand, if the amount of recession of the internal electrodes is reduced in accordance with the shrinkage ratio of the piezoelectric element, it may not be possible to ensure a sufficient amount of recession, and there is a risk that the insulation of the internal electrodes will not be ensured. The present disclosure has been made in view of the above-described circumstances, and aims to provide a piezoelectric ceramic laminate that can ensure insulation while increasing the area of ​​internal electrodes. The present disclosure can be realized in the following forms. [Means for solving the problem]

[0005] [1] A piezoelectric ceramic laminate having a laminate body in which a plurality of piezoelectric ceramic layers and a plurality of plate-shaped internal electrodes are alternately stacked, The laminated body has a hexahedral shape and includes two bottom surfaces located at both ends in the stacking direction, a first side surface and a second side surface arranged back to back, and a third side surface and a fourth side surface arranged back to back, Each of the internal electrodes has an extension portion connected to an external electrode, the lead portion of a first internal electrode that is at least a part of the plurality of internal electrodes is exposed from the first side surface of the laminated body, a side edge portion of the first internal electrode is exposed from the third side surface and / or the fourth side surface, The exposed side edge portions of the first internal electrodes are covered with an insulating coating portion.

[0006] In the piezoelectric ceramic laminate of [1], the side edge portions of the first internal electrodes are exposed from the third side surface and / or the fourth side surface, so that the area of ​​the first internal electrodes can be made larger than in a configuration in which they are not exposed. Furthermore, the exposed side edge portions of the first internal electrodes are covered with an insulating coating portion, so that the insulation of the side edge portions of the first internal electrodes can be ensured. Therefore, a piezoelectric ceramic laminate can be realized in which the area of ​​the internal electrodes can be increased while ensuring insulation.

[0007] [2] The lead portion of a second internal electrode, which is at least a part of the plurality of internal electrodes, is exposed from the second side surface of the laminated body, a side edge portion of the second internal electrode is exposed from the third side surface and / or the fourth side surface, The piezoelectric ceramic laminate according to [1], wherein the first internal electrodes and the second internal electrodes are alternately arranged in the stacking direction.

[0008] In the piezoelectric ceramic laminate of [2], the lead portions of the first internal electrodes can be concentrated on the first side surface of the laminate body, while the lead portions of the second internal electrodes can be concentrated on the second side surface of the laminate body. In addition, the areas of the first internal electrodes and the second internal electrodes can be increased while ensuring insulation.

[0009] [3] A piezoelectric ceramic laminate according to [1] or [2], wherein the lead portion is exposed from a region excluding the edge of the first side surface or a region excluding the edge of the second side surface.

[0010] In the piezoelectric ceramic laminate of [3], when the lead portions are exposed from a region excluding the edge of the first side face, the area exposed from the first side face can be made smaller than when the lead portions are also exposed from the edge of the first side face. This makes it easier to ensure the insulation of the first internal electrode. Similarly, when the lead portions are exposed from a region excluding the edge of the second side face, the area exposed from the second side face can be made smaller than when the lead portions are also exposed from the edge of the second side face. This makes it easier to ensure the insulation of the second internal electrode. [Effects of the Invention]

[0011] The present disclosure can provide a piezoelectric ceramic laminate that can ensure insulation while increasing the area of ​​the internal electrodes. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a piezoelectric ceramic laminate according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an exploded perspective view of a piezoelectric ceramic laminate. [Figure 3] FIG. [Figure 4] FIG. 2 is a plan view of a driving layer having first internal electrodes. [Figure 5] FIG. 10 is a plan view of a driving layer having second internal electrodes. [Figure 6] 1 is a flowchart showing a method for manufacturing a piezoelectric ceramic laminate. DETAILED DESCRIPTION OF THE INVENTION

[0013] First Embodiment The present disclosure will be described in detail below. A piezoelectric ceramic laminate according to a first embodiment will be described with reference to FIGS. 1 to 6. In the following description, with regard to the front-to-back direction, the F direction in FIGS. 1 to 3 is defined as the front. With regard to the up-down direction, the H direction in FIGS. 1 to 3 is defined as the up. With regard to the left-to-right direction, the L direction in FIGS. 1 to 3 is defined as the left.

[0014] 1. Piezoelectric ceramic laminate 10 1 and 2 show an example of a piezoelectric ceramic laminate 10 according to this embodiment. As shown in Fig. 2, the piezoelectric ceramic laminate 10 includes a laminate body 20, a pair of external electrodes 30, and a pair of insulating coating portions 40 (insulating coating layers).

[0015] 2. Laminated body 20 3, the multilayer body 20 has a plurality of piezoelectric ceramic layers 50 and a plurality of plate-shaped internal electrodes 60. In the multilayer body 20, the piezoelectric ceramic layers 50 and the internal electrodes 60 are alternately stacked.

[0016] In the multilayer body 20, a piezoelectric ceramic layer 50 and an internal electrode 60 are stacked together and referred to as a drive layer 71. In the multilayer body 20, a piezoelectric ceramic layer 50 that is not provided with an internal electrode 60 is referred to as a non-drive layer 72. FIG. 3 shows a configuration in which a plurality of stacked drive layers 71 are sandwiched between a pair of non-drive layers 72.

[0017] As shown in FIG. 2, the laminated body 20 has a hexahedral shape. The laminated body 20 has, for example, a rectangular parallelepiped shape that is long in the front-to-rear direction. The laminated body 20 has a first side surface 21, a second side surface 22, a third side surface 23, a fourth side surface 24, and two bottom surfaces (an upper bottom surface 25 and a lower bottom surface 26). The first side surface 21 and the second side surface 22 are arranged back-to-back in the front-to-rear direction. The third side surface 23 and the fourth side surface 24 are arranged back-to-back in the left-to-right direction. The upper bottom surface 25 and the lower bottom surface 26 are located at both ends (upper end and lower end) in the stacking direction (vertical direction).

[0018] 3. Piezoelectric ceramic layer 50 The piezoelectric ceramic layer 50 includes a main phase formed of a crystalline phase (first crystalline phase) made of, for example, an alkali niobate perovskite oxide having piezoelectric properties, and a subphase. The piezoelectric ceramic layer 50 does not include, for example, lead (Pb). The subphase preferably includes a crystalline phase (second crystalline phase) made of a metal oxide. Hereinafter, the first crystalline phase will also be referred to as the "main phase," and a crystalline phase other than the main phase will also be referred to as the "subphase."

[0019] 3-1. Main phase A preferred example of the alkali niobate perovskite oxide is one represented by the following composition formula (formula (1)). (K a Na b Li c M1 d ) e (M2 f )O g …(1) Here, the element M1 is one or more of calcium (Ca), strontium (Sr), and barium (Ba). The element M2 is one or more of niobium (Nb), tantalum (Ta), titanium (Ti), zirconium (Zr), and hafnium (Hf), including at least niobium (Nb). That is, the element M2 is one or more of niobium (Nb), titanium (Ti), zirconium (Zr), and hafnium (Hf). The value of g is any value that can maintain the perovskite crystal structure. That is, the amount of O atoms is set to be sufficient to maintain the perovskite crystal structure.

[0020] The typical composition of alkali niobate perovskite oxides is (K, Na, Li, Ca, Ba) e (Nb,Ti,Zr)O hand has K, Na, and Nb as its main metal components. Because this alkali niobate perovskite oxide has K, Na, and Nb as its main metal components, materials composed of alkali niobate perovskite oxide are also called "KNN" or "KNN material," and the crystalline phase composed of alkali niobate perovskite oxide is also called "KNN phase." Furthermore, materials composed of alkali niobate perovskite oxides whose main metal components are K, Na, Li, Nb, and Ca are also called "KNLNC" or "KNLNC material," and the crystalline phase composed of such materials is also called "KNLNC phase."

[0021] 3-2.Vice Minister The subphase preferably includes a crystalline phase (second crystalline phase) made of one or more metal oxides selected from the following (a) to (e): (A) A-Ti-BO compound (element A is an alkali metal, and element B is at least one of Nb and Ta) (a) M3-Ti-O spinel compounds (element M is a monovalent to pentavalent metal) (U) A2B6O 13 Compounds (element A is a monovalent metal, element B is a divalent to hexavalent metal) (E) A3B5O 15 Compounds (element A is a monovalent or divalent metal, element B is a divalent or pentavalent metal) (E) Single metal oxides consisting of metal elements selected from magnesium (Mg), nickel (Ni), cobalt (Co), iron (Fe), manganese (Mn), chromium (Cr), zirconium (Zr), titanium (Ti), silver (Ag), zinc (Zn), scandium (Sc), and bismuth (Bi).

[0022] The A-Ti-BO compound is a compound containing a composite oxide of element A (potassium (K), rubidium (Rb), cesium (Cs), etc.), titanium (Ti), and element B. In the present disclosure, the A-Ti-BO compound may be one in which element A is an alkali metal, element B is at least one of Nb and Ta, and the contents of element A, element B, and Ti are all non-zero.

[0023] The A-Ti-BO compound is preferably one represented by the following composition formula (2). A 1-x1 Ti 1-x1 B 1+x1 O5…(2) Here, the element B is at least one of niobium (Nb) and tantalum (Ta), and x1 is an arbitrary value. Specific compounds according to the above composition formula include KTiNbO5, K 0.90 Ti 0.90 Nb 1.10 O5,K 0.85 Ti 0.85 Nb 1.15 O5,RbTiNbO5,Rb 0.90 Ti 0.90 Nb 1.10 O5,Rb 0.85 Ti 0.85 Nb 1.15 O5,CsTiNbO5,Cs 0.90 Ti 0.90 Nb 1.10 O5, KTiTaO5, CsTiTaO5, etc. can be used.

[0024] Among A-Ti-BO compounds, those whose main metal components are niobium (Nb), titanium (Ti), and potassium (K) are also called "NTK materials," and their crystalline phase (secondary crystalline phase) is also called "NTK phase."

[0025] As the A-Ti-BO compound, the above-mentioned A 1-x1 Ti 1-x1 B 1+x1 In addition to the compound represented by O5, the compound represented by A1Ti3B1O9 is also available.

[0026] The M3-Ti-O based spinel compound is preferably one represented by the following composition formula: M3 x2 TiO y2 …(4) Here, element M3 is a monovalent to tetravalent metal element, and is at least one of lithium (Li), magnesium (Mg), aluminum (Al), scandium (Sc), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), gallium (Ga), yttrium (Y), zirconium (Zr), tin (Sn), antimony (Sb), silicon (Si), and hafnium (Hf). When lithium (Li) is included as element M3, it is preferable that one or more metal elements other than lithium (Li) be included together with lithium (Li) so that the second crystal phase forms a spinel compound. The coefficients x2 and y2 are relative values ​​when the Ti content is defined as 1. To form a spinel compound, coefficient x2 preferably satisfies 0.5≦x≦5.0. Furthermore, coefficient y2 can be any value that forms a spinel compound, but typically satisfies 2≦y2≦8. The second crystal phase, which is composed of a spinel compound, stabilizes the structure of the first crystal phase, thereby providing a piezoelectric ceramic layer 50 with excellent piezoelectric properties. From the viewpoint of piezoelectric properties, it is preferable to use a second crystal phase represented by the composition formula M32TiO4 or (M4,M5)TiO4, which contains two divalent metal elements M3. Here, elements M4 and M5 are two different metal elements contained in element M3.

[0027] It is particularly preferable that the piezoelectric ceramic layer 50 contains two or more metal elements as the element M3. In this specification, a spinel compound containing two or more metal elements as the element M3 is also referred to as a "composite spinel compound." When the second crystal phase contains a composite spinel compound, the properties of the piezoelectric ceramic layer 50 can be improved.

[0028] As specific examples of the second crystal phase, the following various spinel compounds can be used. Examples of spinel compounds containing Li LiAlTiO4,LiCrTiO4,LiFeTiO4,LiGaTiO4,LiMnTiO4,LiYTiO4,LiScTiO4,LiCo 0.5Ti 1.5 O4, LiMg 0.5 Ti 1.5 O4, LiMn 0.5 Ti 1.5 O4,LiZn 0.5 Ti 1.5 O4,Li 1.33 (Zr,Ti) 1.67 O4 Examples of spinel compounds containing Co o2TiO4,CoZnTiO4,CoMgTiO4,CoNiTiO4,CoFeTiO4,CoMnTiO4 Examples of spinel compounds containing Zn Zn2TiO4,ZnMgTiO4,ZnNiTiO4,ZnFeTiO4,ZnMnTiO4 Examples of spinel compounds containing Mg Mg2TiO4,MgNiTiO4,MgFeTiO4,MgMnTiO4 Examples of spinel compounds containing Ni Ni2TiO4,NiFeTiO4,NiMnTiO4,Ni 1.5 FeTi 0.5 O4,Ni2(Ti,Zr)O4 Examples of Fe-containing spinel compounds Fe2TiO4,FeMnTiO4,Mn 1.5 FeTi 0.5 O4 Examples of spinel compounds containing Mn Mn2TiO4

[0029] A2B6O 13 In the compound, the element A preferably contains at least one of Li (lithium), Na (sodium), and K (potassium), and the element B preferably contains at least one of Co (cobalt), Fe (iron), Mg (magnesium), Ni (nickel), Zr (zirconium), Mn (manganese), Al (aluminum), Nb (niobium), Ta (tantalum), W (tungsten), and Ti (titanium).

[0030] A3B5O 15As the compound, a compound in which the element A (monovalent or divalent metal) is at least one of Ba, Ca, Sr, Na, K, and Li, and the element B (divalent or pentavalent metal) is at least one of Nb, Ta, Ti, Mn, Fe, Ni, Co, Zn, and Zr can be used. Specifically, for example, (Ba,Na,K)3(Nb,Fe)5O 15 ,(Ba,Na,K)3(Nb,Ni,Fe)5O 15 ,(Ba,Na,K)3(Nb,Co,Ni)5O 15 ,(Ba,Na,K)3(Nb,Zn)5O 15 ,(Ba,Na,K)3(Nb,Mn)5O 15 ,(Ba,Na,K)3(Nb,Fe,Zn,Co)5O 15 etc. can be used.

[0031] The subphase may contain a metal oxide other than the above metal oxides (A) to (E). When the subphase contains a metal oxide other than the above metal oxides (A) to (E), the volume ratio of the above metal oxides (A) to (E) to the total volume of the subphase (100%) is preferably greater than 50%, more preferably 70% or more, and even more preferably 80% or more.

[0032] 4. Internal electrode 60 The internal electrodes 60 are plate-shaped. The internal electrodes 60 are made of platinum (Pt), silver (Ag), palladium (Pd), or the like. As shown in Fig. 3, the multiple internal electrodes 60 include multiple first internal electrodes 61 and multiple second internal electrodes 62. The first internal electrodes 61 and the second internal electrodes 62 are alternately arranged in the stacking direction.

[0033] 4-1. First internal electrode 61 As shown in FIGS. 3 and 4, the first internal electrode 61 has an electrode body 61A and an extension portion 61B. The electrode body 61A is a rectangular plate. The left-right width of the electrode body 61A is approximately the same as the left-right width of the piezoelectric ceramic layer 50. As shown in FIG. 4, the electrode body 61A has a front edge portion 61C, a rear edge portion 61D, and side edge portions 61E and 61F. The side edge portion 61E is the right edge portion. The side edge portion 61F is the left edge portion.

[0034] The lead portion 61B is connected to the front external electrode 30. The lead portion 61B protrudes forward from the center portion in the left-right direction of the front edge portion 61C of the electrode body 61A. The lead portion 61B is in the shape of a square plate.

[0035] 4-2. Detailed structure of the first internal electrode 61 As shown in FIG. 2, the lead portion 61B of the first internal electrode 61 is exposed from the first side surface 21 of the laminate body 20. The lead portion 61B is exposed from a region (central portion 21B) excluding the edge portion 21A of the first side surface 21. The edge portion 21A of the first side surface 21 is an annular portion that follows the outer periphery of the first side surface 21. The central portion 21B is a portion of the first side surface 21 that is surrounded by the edge portion 21A.

[0036] A rear edge portion 61D (see FIG. 4) of the first internal electrode 61 is not exposed from the second side surface 22 of the laminate body 20. The rear edge portion 61D of the first internal electrode 61 is located forward and away from the second side surface 22 of the laminate body 20 by a predetermined distance (for example, the same distance as the width of the lead portion 61B in the front-rear direction).

[0037] As shown in Fig. 2, a right side edge 61E of the first internal electrode 61 is exposed from the third side surface 23. The side edge 61E is exposed from a region (central portion 23B) excluding the edge portion 23A of the third side surface 23. The edge portion 23A of the third side surface 23 is an annular portion that follows the outer periphery of the third side surface 23. The central portion 23B is a portion of the third side surface 23 that is surrounded by the edge portion 23A.

[0038] A left side edge 61F (see FIGS. 3 and 4) of the first internal electrode 61 is exposed from the fourth side surface 24. The side edge 61E is exposed from a region (a central portion having the same configuration as the central portion 23B of the third side surface 23) excluding the edge portion of the fourth side surface 24 (an edge portion having the same configuration as the edge portion 23A of the third side surface 23).

[0039] 4-3.Second internal electrode 62 As shown in FIGS. 3 and 5, the second internal electrode 62 has an electrode body 62A and an extension portion 62B. The electrode body 62A is a rectangular plate. The left-right width of the electrode body 62A is approximately the same as the left-right width of the piezoelectric ceramic layer 50. As shown in FIG. 5, the electrode body 62A has a rear edge portion 62C, a front edge portion 62D, and side edges 62E and 62F. The side edge portion 62E is the right edge portion. The side edge portion 62F is the left edge portion.

[0040] The lead portion 62B is connected to the rear external electrode 30. The lead portion 62B protrudes rearward from the center portion in the left-right direction of the rear edge portion 62C of the electrode body 62A. The lead portion 62B is in the shape of a square plate.

[0041] 4-4. Detailed structure of the second internal electrode 62 The lead portion 62B (see FIGS. 3 and 5) of the second internal electrode 62 is exposed from the second side surface 22 of the laminated body 20. The lead portion 62B is exposed from a region (a central portion having the same configuration as the central portion 21B of the first side surface 21) excluding the edge portion of the second side surface 22 (an edge portion having the same configuration as the edge portion 21A of the first side surface 21).

[0042] A front edge portion 62D (see FIG. 5) of the second internal electrode 62 is not exposed from the first side surface 21 of the laminated body 20. More specifically, the front edge portion 62D of the second internal electrode 62 is located rearward from the first side surface 21 of the laminated body 20 by a predetermined distance (for example, the same distance as the width of the lead portion 62B in the front-rear direction).

[0043] 2, a right side edge 62E of the second internal electrode 62 is exposed from the third side surface 23. The side edge 62E is exposed from a region (central portion 23B) of the third side surface 23 excluding the edge portion 23A.

[0044] A left side edge 62F (see FIGS. 3 and 5) of the second internal electrode 62 is exposed from the fourth side surface 24. The side edge 62E is exposed from a region (a central portion having the same configuration as the central portion 23B of the third side surface 23) excluding the edge portion of the fourth side surface 24 (an edge portion having the same configuration as the edge portion 23A of the third side surface 23).

[0045] 5.External electrode 30 As shown in FIGS. 1 and 2, the external electrodes 30 are disposed on the first side surface 21 and the second side surface 22 of the laminated body 20. The external electrodes 30 are rectangular plate-shaped. For example, the size of the external electrodes 30 is slightly smaller than the entire surfaces of the first side surface 21 and the second side surface 22. The material of the external electrodes 30 is, for example, a conductive metal such as copper (Cu), silver (Ag), platinum (Pt), or palladium (Pd).

[0046] The external electrode 30 disposed on the first side surface 21 of the laminated body 20 is in contact with the lead portion 61B of the first internal electrode 61 and is electrically connected to the lead portion 61B.

[0047] The external electrode 30 disposed on the second side surface 22 of the laminated body 20 is in contact with the lead portion 62B of the second internal electrode 62 and is electrically connected to the lead portion 62B.

[0048] 6. Insulating coating part 40 As shown in Figures 1 and 2, the insulating coating portion 40 is arranged on the third side surface 23 and the fourth side surface 24 of the laminated body 20. The insulating coating portion 40 covers the entire surfaces of the third side surface 23 and the fourth side surface 24 of the laminated body 20. The insulating coating portion 40 is in the shape of a square plate. The plate surface of the insulating coating portion 40 has the same size as the third side surface 23 and the fourth side surface 24. The material of the insulating coating portion 40 is not particularly limited as long as it exhibits sufficient insulation properties, and is, for example, a resist (such as an ultraviolet-curable solder resist).

[0049] The insulating covering portion 40 disposed on the third side surface 23 of the laminated body 20 covers a right side edge portion 61E of the exposed first internal electrode 61 and a right side edge portion 62E of the exposed second internal electrode 62. The insulating covering portion 40 disposed on the third side surface 23 of the laminated body 20 contacts the right side edge portion 61E of the exposed first internal electrode 61 and the right side edge portion 62E of the exposed second internal electrode 62 from the right side.

[0050] The insulating covering portion 40 disposed on the fourth side surface 24 of the laminated body 20 covers the left side edge portion 61F of the exposed first internal electrode 61 and the left side edge portion 62F of the exposed second internal electrode 62. The insulating covering portion 40 disposed on the fourth side surface 24 of the laminated body 20 contacts the left side edge portion 61F of the exposed first internal electrode 61 and the left side edge portion 62F of the exposed second internal electrode 62 from the left side.

[0051] 7. Manufacturing method of piezoelectric ceramic laminate 10 6 is a flowchart showing a method for manufacturing the piezoelectric ceramic laminate 10 of the present disclosure. In step T110, first, as raw materials for the first crystal phase (main phase), necessary materials are selected from K2CO3 powder, Na2CO3 powder, Li2CO3 powder, CaCO3 powder, SrCO3 powder, BaCO3 powder, Nb2O5 powder, Ta2O5 powder, TiO2 powder, ZrO2 powder, HfO2 powder, MgO powder, Fe2O3 powder, CoO powder, ZnO powder, etc., and weighed out according to the values ​​of the coefficients a, b, c, d, e, f, and g in the composition formula (1) of the main phase. As raw materials for the second crystal phase (subphase), necessary materials are selected from TiO2 powder, Li2CO3 powder, Na2CO3 powder, K2CO3 powder, Co3O4 powder, Fe2O3 powder, MgO powder, NiO powder, ZrO2 powder, MnO2 powder, Al2O3 powder, Nb2O5 powder, Ta2O5 powder, WO3 powder, etc., and weighed out according to the value of coefficient x1 in the composition formula (2) of the subphase. The weighed raw materials for the main phase and subphase are mixed to obtain a mixed powder.

[0052] In step T120, the mixed powder obtained in step T110 is calcined in an air atmosphere at 600°C to 1200°C for 1 hour to 10 hours to produce a calcined powder. The relationship between the subphase ratio (wt%) during mixing in step T110 and the subphase ratio (volume%) in the finally obtained piezoelectric ceramic layer 50 can be empirically determined in advance.

[0053] In step T130, the calcined powder obtained in step T120, a binder, and a solvent are wet mixed and formed into a green sheet of a predetermined thickness by a casting sheet molding.

[0054] In step T140, the green sheet obtained in step T130 is punched out to a size of 150 mm square, and internal electrodes are printed using silver (Ag) paste, silver (Ag) / palladium (Pd) paste, or platinum (Pt) paste to obtain a driving layer. Here, some of the punched green sheets without internal electrodes printed on them (referred to as non-driving layers) are also prepared.

[0055] In step T150, the driving layers and non-driving layers obtained in step T140 are stacked in a predetermined number and order, and pressure-laminated at 40°C to 80°C and a pressure of 5MPa to 100MPa. The stack is then cut into small pieces.

[0056] In step T160, the small pieces obtained in step T150 are degreased in an air atmosphere at a holding temperature of 500°C to 800°C for a holding time of 2 hours to 100 hours.

[0057] In step T170, the degreased small pieces obtained in step T160 are fired in an air atmosphere at 900°C to 1400°C for 1 hour to 100 hours to obtain a fired body.

[0058] In step T180, the four sides of the rectangular sintered body obtained in step T170 are diced to reduce its dimensions and expose the internal electrodes. The sintered body is then processed to the required dimensional accuracy. For example, the top and bottom surfaces of the sintered body (both end surfaces in the stacking direction) are polished to adjust the thickness and achieve parallelism.

[0059] In step T190, a pair of side electrodes (external electrodes) is printed on the fired body, and the fired body is baked at 600°C to 800°C.

[0060] In step T200, the surfaces (four side surfaces) of the fired body baked in step T190 other than the upper and lower bottom surfaces are insulated to form insulating coating portions. In step T210, the fired body with the pair of side electrodes attached is subjected to a polarization treatment.

[0061] The above-described manufacturing method is an example, and various other steps and processing conditions can be used to manufacture the piezoelectric ceramic laminate 10.

[0062] 8. Application Examples of the Piezoelectric Ceramic Laminate 10 The piezoelectric ceramic laminate 10 can be widely used for actuators, oscillations, vibration detection, pressure detection, piezoelectric devices, etc. For example, it can be used in various devices such as actuators for mass flow controllers, piezoelectric motors, piezoelectric filters, piezoelectric transformers, piezoelectric ultrasonic transducers, piezoelectric gyro sensors, and knock sensors.

[0063] 9. Effects of this embodiment In the piezoelectric ceramic laminate 10 of the first embodiment, the right side edge 61E of the first internal electrode 61 is exposed from the third side surface 23, and the left side edge 61F is exposed from the fourth side surface 24, so that the area of ​​the first internal electrode 61 can be made larger than in a configuration in which they are not exposed. Furthermore, the exposed side edges 61E, 61F of the first internal electrode 61 are covered with the insulating cover 40, so that insulation of the side edges 61E, 61F of the first internal electrode 61 can be ensured. Therefore, it is possible to realize a piezoelectric ceramic laminate 10 in which insulation can be ensured while the area of ​​the internal electrode 60 (first internal electrode 61) is increased.

[0064] In the piezoelectric ceramic laminate 10 of the first embodiment, the lead portion 62B of the second internal electrode 62 is exposed from the second side surface 22 of the laminate body 20. A right side edge portion 62E of the second internal electrode 62 is exposed from the third side surface 23, and a left side edge portion 62F is exposed from the fourth side surface 24. The first internal electrodes 61 and the second internal electrodes 62 are arranged alternately in the stacking direction (vertical direction). With this configuration, the lead portions 61B of the first internal electrodes 61 can be concentrated on the first side surface 21 side of the laminate body 20, while the lead portions 62B of the second internal electrodes 62 can be concentrated on the second side surface 22 side of the laminate body 20. Furthermore, the area of ​​each of the first internal electrodes 61 and the second internal electrodes 62 can be increased while ensuring insulation.

[0065] For example, when the piezoelectric ceramic laminate 10 is used for an actuator, the internal electrodes 60 (first internal electrode 61, second internal electrode 62) are exposed from the third side surface 23 and the fourth side surface 24, so that the area of ​​the internal electrodes 60 can be increased, and the active region (region overlapping with the internal electrodes 60 in the stacking direction) in the laminate body 20 can be made large. Therefore, the displacement portion in the laminate body 20 can be made large.

[0066] On the third side surface 23, the first internal electrode 61 (specifically, the right side edge 61E) and the second internal electrode 62 (specifically, the right side edge 62E) are covered with the insulating coating 40, thereby insulating the first internal electrode 61 and the second internal electrode 62. Therefore, it is possible to prevent a leakage current from flowing between the first internal electrode 61 and the second internal electrode 62 on the third side surface 23. Similarly, on the fourth side surface 24, the first internal electrode 61 (specifically, the left side edge 61F) and the second internal electrode 62 (specifically, the left side edge 62F) are covered with the insulating coating 40, thereby insulating the first internal electrode 61 and the second internal electrode 62. Therefore, it is possible to prevent a leakage current from flowing between the first internal electrode 61 and the second internal electrode 62 on the fourth side surface 24.

[0067] In the piezoelectric ceramic laminate 10 of the first embodiment, the lead portions 61B of the first internal electrodes 61 are exposed from a region (central portion 21B) excluding the edge portions 21A of the first side surfaces 21, and the range exposed from the first side surfaces 21 can be made smaller than in a configuration in which the lead portions 61B are also exposed from the edge portions 21A of the first side surfaces 21. This makes it easier to ensure the insulation of the first internal electrodes 61.

[0068] Similarly, the drawn portion 62B of the second internal electrode 62 is exposed from a region excluding the edge of the second side face 22, and the range exposed from the second side face 22 can be made smaller than in a configuration in which the drawn portion 62B is exposed from the edge of the second side face 22 as well. This makes it easier to ensure the insulation of the second internal electrode 62.

[0069] <Other Examples> The present invention is not limited to the embodiments described above and illustrated in the drawings, and the following embodiments are also included within the technical scope of the present invention.

[0070] (1) In the first embodiment, the side edge portions 61E, 61F on both the left and right sides of the first internal electrode 61 are exposed from the third side surface 23 and the fourth side surface 24, respectively. However, a configuration in which only one of the side edge portions 61E, 61F is exposed may also be used. In this case, the insulating coating portion 40 does not need to be provided on the third side surface 23 or the fourth side surface 24 where the first internal electrode 61 is not exposed.

[0071] (2) In the first embodiment, the third side surface 23 and the fourth side surface 24 of the laminated body 20 are covered with the insulating coating portion 40, but at least one of the first side surface 21 and the second side surface 22 may also be covered with the insulating coating portion 40 via the external electrode 30.

[0072] (3) In the first embodiment, the laminated body 20 has a rectangular parallelepiped shape that is long in the front-rear direction, but it may have other shapes such as a cube.

[0073] (4) In the first embodiment, the piezoelectric ceramic layer 50 does not contain lead (Pb), but may contain lead (Pb). [Explanation of symbols]

[0074] 10: Piezoelectric ceramic laminate 20: Laminated body 21: First side 21A: Edge 21B: Central part 22: Second side 23: Third aspect 23A: Edge 23B: Central part 24: Fourth aspect 25: Upper base (bottom) 26: Bottom surface (bottom surface) 30: External electrode 40: Insulation coating 50: Piezoelectric ceramic layer 60: Internal electrode 61: 1st internal electrode 61A: Electrode body 61B: Drawer section 61C: Leading edge 61D: Trailing edge 61E, 61F: Side edges 62: Second internal electrode 62A: Electrode body 62B: Drawer section 62C: Trailing edge 62D: Leading edge 62E,62F: Side edge 71: Driving Layer 72: Non-driven layer

Claims

1. A piezoelectric ceramic laminate including a laminate body in which a plurality of piezoelectric ceramic layers and a plurality of plate-shaped internal electrodes are alternately stacked, The laminated body has a hexahedral shape and includes two bottom surfaces located at both ends in the stacking direction, a first side surface and a second side surface arranged back to back, and a third side surface and a fourth side surface arranged back to back, Each of the internal electrodes has an extension portion connected to an external electrode, the lead portion of a first internal electrode that is at least a part of the plurality of internal electrodes is exposed from the first side surface of the laminated body, a side edge portion of the first internal electrode is exposed from the third side surface and / or the fourth side surface, The exposed side edge portions of the first internal electrodes are covered with an insulating coating portion.

2. the lead portion of a second internal electrode that is at least a part of the plurality of internal electrodes is exposed from the second side surface of the laminated body, a side edge portion of the second internal electrode is exposed from the third side surface and / or the fourth side surface, The piezoelectric ceramic laminate according to claim 1 , wherein the first internal electrodes and the second internal electrodes are alternately arranged in the stacking direction.

3. 3. The piezoelectric ceramic laminate according to claim 1, wherein the lead portion is exposed from a region excluding an edge of the first side surface or a region excluding an edge of the second side surface.

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