Multilayer ceramic capacitor

Abstract

The present invention provides a multilayer ceramic capacitor capable of suppressing energy loss in a high frequency region, exhibiting an ESL reduction effect, and minimizing internal structure defects.　The width-direction W dimension of a laminate 2 is greater than the length-direction L dimension of the laminate. A plurality of internal electrodes 15 have a plurality of internal electrode groups 16, each of which being a group consisting of internal electrodes 15 continuously adjacent in the lamination direction T and exposed to the same end face C. Each of the internal electrode groups 16 has an inside internal electrode 151, which is the internal electrode 15 closest to the central region in the lamination direction T of the laminate 2, and an inside internal electrode 151, which is the internal electrode 15 closest to the surface of the laminate 2. The inside internal electrode 151 of the internal electrode group 16 closest to the surface of the laminate 2 out of the plurality of internal electrode groups 16 has an inside curved part 151a, which is a part curved in a shape projecting toward the center part of the laminate 2 in the lamination direction T.

Description

Multilayer ceramic capacitors

[0001] The present invention relates to a multilayer ceramic capacitor.

[0002] Conventionally, there has been a multilayer ceramic capacitor that includes a laminate in which dielectric layers and internal electrodes are alternately stacked, and external electrodes provided on both end surfaces of the laminate. In recent years, multilayer ceramic capacitors with excellent high-frequency characteristics have been developed (see, for example, Patent Document 1).

[0003] The multilayer ceramic capacitor of Patent Document 1 has an internal electrode group composed of internal electrodes adjacent to each other in the stacking direction. This allows a high Q value to be obtained in the high frequency range. In a high frequency circuit using a multilayer ceramic capacitor with a high Q value, energy loss within the high frequency circuit is suppressed. Furthermore, in a multilayer ceramic capacitor whose width dimension is larger than its length dimension, the distance between external electrodes can be shortened and the width dimension of the external electrodes can be increased compared to a normal multilayer ceramic capacitor, thereby reducing ESL.

[0004] Japanese Patent Application Laid-Open No. 2012-9817

[0005] However, in the multilayer ceramic capacitor of Patent Document 1, it is difficult to ensure adhesion between the internal electrodes and the dielectric layers around the internal electrode group. As a result, internal structural defects such as cracks and delamination may occur between the internal electrodes and the dielectric layers. In particular, in a multilayer ceramic capacitor whose width dimension is larger than its length dimension, the gap area from the longitudinal end of the first internal electrode on the second end face side to the second end face and the gap area from the longitudinal end of the second internal electrode on the first end face side to the first end face tend to be large, which may make internal structural defects more likely to occur between the internal electrodes and the dielectric layers.

[0006] An object of the present invention is to provide a multilayer ceramic capacitor that can suppress energy loss in the high frequency range, has an effect of reducing ESL, and can suppress internal structural defects.

[0007] In order to achieve the above object, a multilayer ceramic capacitor according to the present invention comprises: an inner layer portion including a plurality of dielectric layers and a plurality of internal electrodes that are alternately stacked; a laminate having a pair of main surfaces that face each other in a stacking direction; a pair of side surfaces that face each other in a width direction that is a direction perpendicular to the stacking direction; and a pair of end faces that face each other in a length direction that is a direction perpendicular to the stacking direction and the width direction; and external electrodes that are arranged on the end faces and connected to the internal electrodes, wherein the dimension of the laminate in the width direction is greater than the dimension of the laminate in the length direction, and the plurality of internal electrodes are adjacent to each other continuously in the stacking direction and are arranged in the same direction. The laminate has a plurality of internal electrode groups, which are groups consisting of the internal electrodes exposed at one of the end faces, and each internal electrode group has an inner internal electrode, which is the internal electrode that is closest to the center of the stacking direction of the laminate among the internal electrodes that constitute the internal electrode group, and an outer internal electrode, which is the internal electrode that is closest to the surface of the laminate among the internal electrodes that constitute the internal electrode group, and the inner internal electrode of the internal electrode group that is closest to the surface of the laminate among the plurality of internal electrode groups has an inner curved portion that is curved in a shape that is convex toward the center of the stacking direction of the laminate.

[0008] According to the present invention, it is possible to provide a multilayer ceramic capacitor that can suppress energy loss in the high frequency range, has an effect of reducing ESL, and can suppress internal structural defects.

[0009] 2 is a schematic perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention, a cross-sectional view taken along line II-II in FIG. 1, a cross-sectional view taken along line III-III in FIG. 1, and an enlarged view of part IV in FIG.

[0010] A multilayer ceramic capacitor 1 according to an embodiment of the present invention will now be described with reference to FIGS.

[0011] (Multilayer Ceramic Capacitor 1) As shown in Fig. 1, the multilayer ceramic capacitor 1 is a multilayer ceramic capacitor with a so-called two-terminal structure. The multilayer ceramic capacitor 1 includes a laminate 2 and a pair of external electrodes 3. The laminate 2 is substantially rectangular and has six outer surfaces. The laminate 2 includes an inner layer portion 11 in which a dielectric layer 14 and an internal electrode 15 are stacked.

[0012] In this specification, the direction in which the dielectric layers 14 and the internal electrodes 15 are stacked in the multilayer ceramic capacitor 1 is referred to as the stacking direction T. One of the directions perpendicular to the stacking direction T is referred to as the length direction L. The direction perpendicular to both the length direction L and the stacking direction T is referred to as the width direction W.

[0013] Of the six outer surfaces of the laminate 2, a pair of outer surfaces on both sides in the stacking direction T are referred to as the first main surface AA and the second main surface AB, a pair of outer surfaces extending in the stacking direction T and on both sides in the width direction W are referred to as the first side surface BA and the second side surface BB, and a pair of outer surfaces extending in the stacking direction T and on both sides in the length direction L are referred to as the first end surface CA and the second end surface CB.

[0014] The first main surface AA and the second main surface AB may be collectively referred to as "main surfaces A." The first side surface BA and the second side surface BB may be collectively referred to as "side surfaces B." The first end surface CA and the second end surface CB may be collectively referred to as "end surfaces C."

[0015] A cross section parallel to the stacking direction T and the length direction L is referred to as an "LT cross section." The cross section of FIG. 2 is an LT cross section passing through the center of the multilayer ceramic capacitor 1 in the width direction W. A cross section parallel to the stacking direction T and the width direction W is referred to as a "WT cross section." The cross section of FIG. 3 is a WT cross section passing through the center of the multilayer ceramic capacitor 1 in the length direction L.

[0016] (Laminate 2) The laminate 2 has an inner layer portion 11 and a pair of outer layer portions 12 arranged on either side of the inner layer portion 11 in the stacking direction T. The portions where three outer surfaces of the laminate 2 intersect are referred to as "corners." The portions where two outer surfaces of the laminate 2 intersect are referred to as "ridge portions." The corners and ridge portions of the laminate 2 are preferably rounded.

[0017] The dimension of the laminate 2 in the width direction W is larger than the dimension of the laminate 2 in the length direction L. The dimension of the laminate 2 in the length direction L is, for example, 0.2 mm or more and 0.6 mm or less. The dimension of the laminate 2 in the width direction W is, for example, 0.4 mm or more and 1.0 mm or less. The dimension of the laminate 2 in the stacking direction T is, for example, 0.1 mm or more and 0.9 mm or less. The external dimensions of the multilayer ceramic capacitor 1 can be measured with a micrometer.

[0018] 2 and 3, the inner layer portion 11 has a plurality of dielectric layers 14 and a plurality of internal electrodes 15. The dielectric layers 14 and the internal electrodes 15 are alternately stacked.

[0019] The dielectric layer 14 is mainly composed of a ceramic material containing at least one of Ca, Sr, Zr, and Ti.

[0020] For example, the dielectric layer 14 is mainly composed of a ceramic material having a perovskite structure represented by the general formula ABO3 containing Ca and Zr. １－ｘ－ｙ , Sr ｘ , Ba ｙ ) m(Zr １－ｚ－α , Ti ｚ , Hf α ) O ３ where x is 0 or more and 1 or less, y is 0 or more and 0.4 or less, m is 1.0 or more and 1.1 or less, z is 0 or more and 0.2 or less, and α is 0 or more and 0.3 or less. The dielectric layer 14 is, for example, CaZrO3 (calcium zirconate). The ceramic material forming the dielectric layer 14 may contain all of Ca, Zr, and Ti as main components. For example, the dielectric layer 14 may be Ca(Zr0.9Ti0.1)O3, which is a material in which part of ZrO3 or Zr in CaZrO3 is substituted with Ti.

[0021] Furthermore, the dielectric layer 14 is not limited to a material whose main component is a ceramic material having a perovskite structure represented by the general formula ABO3 containing Ca and Zr. The dielectric layer 14 may be made of, for example, TiO2 (titanium oxide).

[0022] The dielectric layer 14 is preferably made of (Ca１－ｘ－ｙ , Sr ｘ , Ba ｙ ) m(Zr １－ｚ－α , Ti ｚ , Hf α ) O ３ where x is 0 or more and 1 or less, y is 0 or more and 0.4 or less, m is 1.0 or more and 1.1 or less, z is 0 or more and 0.2 or less, and α is 0 or more and 0.3 or less, or is TiO2.

[0023] Depending on the purpose, additives may be added to the ceramic material forming the dielectric layer 14. Examples of such additives include oxides of rare earth elements such as Mn, Mg, Dy, and Cr, or V, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb, and Y, or oxides of Co, Ni, Li, B, Na, K, and Si, or glass.

[0024] The thickness of the dielectric layer 14 (i.e., the dimension T in the stacking direction) can be observed by measuring the distance between two adjacent first internal electrodes 15A or the distance between two adjacent second internal electrodes 15B, and is, for example, 1 μm or more and 100 μm or less.

[0025] The internal electrode 15 is primarily composed of a conductive metal, such as at least one of Cu, Ni, Ag, Pd, an alloy of Ag and Pd, and Au. The term "main component" refers to a component that accounts for 50% by mass or more of the components constituting the internal electrode. These metals may be compounds containing these metal elements or alloys with other metals. The internal electrode 15 preferably contains Cu. The internal electrode 15 is formed by sintering a conductive paste containing a metal powder that serves as a conductor, an organic solvent, a binder, and a dispersant on the dielectric layer 14.

[0026] The total number of internal electrodes 15 is, for example, 4 to 100. The internal electrodes 15 are layered. The thickness per layer of the internal electrodes 15 (i.e., the dimension T in the stacking direction) is, for example, 0.5 μm to 3 μm, and preferably 1.2 μm to 2.4 μm. If the thickness of the internal electrodes 15 is less than 1.2 μm, the Q value may be too small. If the thickness of the internal electrodes 15 is greater than 2.4 μm, the interface between the internal electrodes 15 and the dielectric layers 14 may peel off during firing due to the difference in shrinkage between the internal electrodes 15 and the dielectric layers 14.

[0027] The internal electrode 15 includes a plurality of first internal electrodes 15A and a plurality of second internal electrodes 15B. The first internal electrodes 15A are exposed only at the first end face CA. The second internal electrodes 15B are exposed only at the second end face CB.

[0028] The multiple first internal electrodes 15A include multiple first internal electrode groups 16A, which are groups of first internal electrodes 15A that are continuously adjacent to each other in the stacking direction T and exposed to the same end face (more specifically, the first end face CA).

[0029] Each of the first internal electrode groups 16A is made up of a plurality of first internal electrodes 15A, and more specifically, two first internal electrodes 15A. In the first internal electrode groups 16A, a dielectric layer 14 is disposed between adjacent first internal electrodes 15A. The first internal electrode groups 16A include a first inner internal electrode 151A which is the first internal electrode 15A closest to the center of the laminate 2 in the stacking direction T of the laminate 2 among the first internal electrodes 15A constituting the first internal electrode group 16A, and a first outer internal electrode 152A which is the first internal electrode 15A closest to the surface of the laminate 2 among the first internal electrodes 15A constituting the first internal electrode group 16A.

[0030] The second internal electrodes 15B include a second internal electrode group 16B, which is a group of second internal electrodes 15B that are adjacent to each other in the stacking direction T and exposed to the same end face (more specifically, the second end face CB).

[0031] Each second internal electrode group 16B is made up of a plurality of second internal electrodes 15B, and more specifically, two second internal electrodes 15B. In each second internal electrode group 16B, a dielectric layer 14 is disposed between adjacent second internal electrodes 15B. Each second internal electrode group 16B has a second inner internal electrode 151B which is the second internal electrode 15B closest to the center of the laminate 2 in the stacking direction T of the laminate 2 among the second internal electrodes 15B constituting the second internal electrode group 16B, and a second outer internal electrode 152B which is the second internal electrode 15B closest to the surface of the laminate 2 among the second internal electrodes 15B constituting the second internal electrode group 16B.

[0032] The plurality of first internal electrode groups 16A and the plurality of second internal electrode groups 16B are alternately arranged in the stacking direction T. A dielectric layer 14 is arranged between adjacent first internal electrode groups 16A and second internal electrode groups 16B. A portion of the first internal electrode group 16A and a portion of the second internal electrode group 16B face each other in the stacking direction T.

[0033] A capacitance occurs between the first internal electrode group 16A and the second internal electrode group 16B. One first internal electrode group 16A can be regarded as one first internal electrode 15A having a large thickness. One second internal electrode group 16B can be regarded as one second internal electrode 15B having a large thickness. Therefore, it is possible to obtain the same effect as when the thickness of one internal electrode 15 is increased, and it is possible to reduce the equivalent series resistance (ESR). As a result, a multilayer ceramic capacitor 1 with low loss can be obtained.

[0034] The first internal electrode group 16A and the second internal electrode group 16B may be collectively referred to as the "internal electrode group 16." The first internal internal electrode 151A and the second internal internal electrode 151B may be collectively referred to as the "internal internal electrode 151." The first external internal electrode 152A and the second external internal electrode 152B may be collectively referred to as the "external internal electrode 152."

[0035] (Auxiliary Electrode 21) The inner layer portion 11 also includes a plurality of auxiliary electrodes 21 provided at intervals in the length direction L from the internal electrodes 15, for example.

[0036] The auxiliary electrode 21, like the internal electrode 15, is made of an appropriate conductive material such as a metal such as Cu, Ni, Ag, Pd, or Au, or an alloy containing at least one of these metals, such as an Ag-Pd alloy.

[0037] The auxiliary electrode 21 includes a plurality of first auxiliary electrodes 21A and a plurality of second auxiliary electrodes 21B.

[0038] The first auxiliary electrode 21A is provided at a distance from the second internal electrode 15B in the longitudinal direction L. The first auxiliary electrode 21A is exposed at the first end face CA. The first auxiliary electrode 21A is connected to the first external electrode 3A. The first auxiliary electrode 21A and the first internal electrode 15A face each other in the stacking direction T.

[0039] The plurality of first auxiliary electrodes 21A includes a plurality of first auxiliary electrode groups 22A, which are groups of first auxiliary electrodes 21A adjacent to each other in the stacking direction T.

[0040] Each first auxiliary electrode group 22A is made up of a plurality of first auxiliary electrodes 21A, more specifically, two first auxiliary electrodes 21A. The first auxiliary electrode group 22A is provided at a distance from the second internal electrode group 16B in the longitudinal direction L. In each first auxiliary electrode group 22A, a dielectric layer 14 is disposed between adjacent first auxiliary electrodes 22A of the first auxiliary electrode group 22A.

[0041] The second auxiliary electrode 21B is provided at a distance from the first internal electrode 15A in the longitudinal direction L. The second auxiliary electrode 21B is exposed at the second end face CB. The second auxiliary electrode 21B is connected to the second external electrode 3B. The second auxiliary electrode 21B and the second internal electrode 15B face each other in the stacking direction T.

[0042] The plurality of second auxiliary electrodes 21B includes a plurality of second auxiliary electrode groups 22B, which are groups of second auxiliary electrodes 21B adjacent to each other in the stacking direction T.

[0043] Each second auxiliary electrode group 22B is made up of a plurality of second auxiliary electrodes 21B, more specifically, two second auxiliary electrodes 21B. The second auxiliary electrode group 22B is provided at a distance from the first internal electrode group 16A in the longitudinal direction L. In the second auxiliary electrode group 22B, a dielectric layer 14 is disposed between adjacent second auxiliary electrodes 22B of the second auxiliary electrode group 22B.

[0044] The first auxiliary electrode group 22A and the second auxiliary electrode group 22B may be collectively referred to as the "auxiliary electrode group 22."

[0045] (Outer Layer Portion 12) The outer layer portion 12 is formed of the same material as the dielectric layer 14 of the inner layer portion 11. Note that no inner electrode 15 is disposed in the outer layer portion 12.

[0046] (External electrode 3) The external electrode 3 is disposed on the end face C and connected to the internal electrode 15. The external electrode 3 includes a first external electrode 3A disposed on the first end face CA and connected to the first internal electrode 15A, and a second external electrode 3B disposed on the second end face CB and connected to the second internal electrode 15B. The first external electrode 3A covers not only the first end face CA but also part of the main face A and part of the side face B. The second external electrode 3B covers not only the second end face CB but also part of the main face A and part of the side face B.

[0047] As described above, the dimension of the laminate 2 in the width direction W is greater than the dimension of the laminate 2 in the length direction L. The multilayer ceramic capacitor 1 is a so-called LW-reversed multilayer ceramic capacitor. By making the multilayer ceramic capacitor 1 an LW-reversed multilayer ceramic capacitor, the distance between the external electrodes 3 can be shortened and the dimension of the external electrodes 3 in the width direction W can be increased compared to a normal multilayer ceramic capacitor, thereby reducing the ESL.

[0048] The external electrodes 3 each include a base electrode layer 31 disposed on the surface of the laminate 2 and a plating layer 32 disposed on the base electrode layer 31 .

[0049] The base electrode layer 31 is mainly composed of a conductive metal, and contains, for example, Cu, Ni, Ag, Pd, Au, an Ag-Pd alloy, or the like. The base electrode layer 31 preferably contains Cu. The base electrode layer 31 is, for example, a baked layer containing a conductive metal and glass. The maximum thickness of the base electrode layer 31 is 5 μm or more and 50 μm or less. The main component of the base electrode layer refers to a component that accounts for 50 mass % or more of the components that make up the base electrode layer.

[0050] The plating layer 32 is made of, for example, one metal selected from the group consisting of Cu, Ni, Ag, Pd, Au, and Sn, or an alloy containing such a metal. The plating layer 32 includes, for example, a first plating layer 321 disposed on the base electrode layer 31 and a second plating layer 322 disposed on the first plating layer 321.

[0051] The first plating layer 321 is, for example, a Ni plating layer. The second plating layer 322 is, for example, a Sn (tin) plating layer. The plating layer 32 may have a single-layer structure. The thickness of each plating layer 32 is preferably 0.5 μm or more and 10 μm or less.

[0052] Here, of the multiple internal electrode groups 16, the inner internal electrode 151 of the internal electrode group 16 closest to the surface of the laminate 2 has an inner curved portion 151a that is a portion curved in a shape that is convex toward the center of the stacking direction T. For example, of the multiple first internal electrode groups 16A, the first inner internal electrode 151A of the first internal electrode group 16A closest to the first principal surface AA has a first inner curved portion 151Aa that is a portion curved in a shape that is convex toward the center of the stacking direction T of the laminate 2.

[0053] The inner curved portion is defined as a curved portion of the inner internal electrode, the shortest distance between the vertex of the curved portion and a virtual line (referred to as a "first virtual line L1") connecting the ends of the inner internal electrode in the length direction L is 0.1 μm or more. The first virtual line L1 is a virtual line having its origin at a portion of the length direction end of the inner internal electrode closest to the center in the stacking direction.

[0054] The first inner curved portion 151Aa has, for example, a substantially V-shape or a substantially U-shape that protrudes toward the center of the stacking direction T of the stack 2.

[0055] Of the multiple first internal electrode groups 16A, the first outer internal electrode 152A of the internal electrode group 16 closest to the surface of the laminate 2 has, for example, a first outer curved portion 152Aa that is a portion curved in a shape that is convex toward the center of the stacking direction T. The first outer curved portion 152Aa and the first inner curved portion 151Aa overlap in the stacking direction T.

[0056] The region of the inner layer portion 11 extending in the stacking direction T between the internal electrode 15 exposed at one end face C and the auxiliary electrode 21 located between the internal electrode 15 and the other end face C is referred to as the "extended region 25." The portion of the internal electrode 15 exposed at the other end face C that is located in the extended region 25 has an apex of the inner curved portion 151a. For example, the region of the inner layer portion 11 extending in the stacking direction T between the second internal electrode 15B and the first auxiliary electrode 21A located between the second internal electrode 15B and the first end face CA is referred to as the "first extended region 25A." The portion of the first inner internal electrode 151A that is located in the first extended region 25A has an apex of the first inner curved portion 151Aa. However, it is sufficient that the apex of the first inner curved portion 151Aa is located in the first extended region 25A, and a portion of the first inner curved portion 151Aa does not have to be located in the first extended region 25A. The "vertex of the inner curved portion" refers to the portion of the inner curved portion that is closest to the center of the laminate in the stacking direction.

[0057] Of the multiple internal electrode groups 16, in the internal electrode group 16 closest to the surface of the laminate 2, the magnitude of curvature of the inner curved portion 151a is larger than the magnitude of curvature of the outer internal electrode 152. For example, as shown in Fig. 4, the magnitude of curvature of the first inner curved portion 151Aa (referred to as "TI") is larger than the magnitude of curvature of the first outer internal electrode 152A (referred to as "TO").

[0058] The magnitude of the curvature of the inner curved portion is the shortest distance between the apex of the curved portion of the inner internal electrode and the first virtual line L1.

[0059] The magnitude of curvature of the outer internal electrode is the shortest distance between the second virtual line L2 and the intersection of the outer internal electrode and the third virtual line L3, where the second virtual line L2 is an imaginary line connecting the respective ends of the outer internal electrode in the length direction L, and the third virtual line L3 is an imaginary line extending the line segment connecting the first virtual line L1 and the vertex of the inner internal electrode over the shortest distance. The second virtual line L2 is an imaginary line that originates from a portion of the length direction end of the outer internal electrode that is closest to the center in the stacking direction. The outer internal electrode does not have to be curved.

[0060] The magnitude of the curvature of the inside internal electrode 151 is preferably 0.5 μm or more and 3 μm or less. For example, the magnitude of the curvature of the first inside internal electrode 151A is preferably 0.5 μm or more and 3 μm or less.

[0061] The auxiliary electrodes 21 are located on the extensions of the internal electrodes 15. For example, the first auxiliary electrode 21A is located on the extensions of the second internal electrode 15B. The end of the first auxiliary electrode 21A on the second internal electrode 15B side and the end of the second internal electrode 15B on the first auxiliary electrode 21A side face each other in the longitudinal direction L.

[0062] The "extension line of the internal electrode" is a virtual straight line connecting the center of one end in the stacking direction T of the internal electrode and the center of the other end in the stacking direction T of the internal electrode.

[0063] Furthermore, among the plurality of second internal electrode groups 16B, the second inner internal electrode 151B of the second internal electrode group 16B closest to the second main surface AB has a second inner curved portion 151Ba that is a portion curved in a shape that is convex toward the center of the stacking direction T of the laminate 2. The second inner curved portion 151Ba has, for example, a substantially V-shape or a substantially U-shape that is convex toward the center of the stacking direction T of the laminate 2.

[0064] Of the plurality of second internal electrode groups 16B, the second outer internal electrode 152B of the second internal electrode group 16B closest to the surface of the laminate 2 has, for example, a second outer curved portion 152Ba that is a portion curved in a shape that is convex toward the center of the stacking direction T. The second outer curved portion 152Ba and the second inner curved portion 151Ba overlap in the stacking direction T.

[0065] A region of the inner layer portion 11 extending in the stacking direction T from the region between the first internal electrode 15A and the second auxiliary electrode 21B located between the first internal electrode 15A and the second end face CB is referred to as a "second extension region 25B." A portion of the second inner internal electrode 151B located in the second extension region 25B has an apex of a second inner curved portion 151Ba. However, it is sufficient that the apex of the second inner curved portion 151Ba is located in the second extension region 25B, and a portion of the second inner curved portion 151Ba does not have to be located in the second extension region 25B.

[0066] The degree of curvature of the second inner curved portion 151Ba is greater than the degree of curvature of the second outer curved portion 152Ba.

[0067] The magnitude of the curvature of the second inner internal electrode 151B is preferably 0.5 μm or more and 3 μm or less.

[0068] The second auxiliary electrode 21B is present on an extension of the first internal electrode 15A.

[0069] The first internal electrode group 16A and the second internal electrode group 16B may be collectively referred to as the "internal electrode group 16." The first internal internal electrode 151A and the second internal internal electrode 151B may be collectively referred to as the "internal internal electrode 151." The first internal curved portion 151Aa and the second internal curved portion 151Ba may be collectively referred to as the "internal curved portion 151a." The first external internal electrode 152A and the second external internal electrode 152B may be collectively referred to as the "external internal electrode 152." The first external curved portion 152Aa and the second external curved portion 152Ba may be collectively referred to as the "external curved portion 152a." The first extension region 25A and the second extension region 25B may be collectively referred to as the "extension region 25."

[0070] (Method for Manufacturing Multilayer Ceramic Capacitor 1) Next, a method for manufacturing the multilayer ceramic capacitor 1 according to the embodiment will be described.

[0071] (Printing Process) First, a dielectric sheet, a conductive paste for the internal electrodes, and a conductive paste for the auxiliary electrodes are prepared. The dielectric sheet, the conductive paste for the internal electrodes, and the conductive paste for the auxiliary electrodes each contain a binder and a solvent. The binder and solvent may be, for example, publicly known materials. The conductive paste for the internal electrodes and the conductive paste for the auxiliary electrodes each contain a metal powder. Note that the components contained in the conductive paste for the internal electrodes and the components contained in the conductive paste for the auxiliary electrodes may be different from each other.

[0072] Next, the conductive paste for the internal electrodes and the conductive paste for the auxiliary electrodes are printed in a predetermined pattern on the dielectric sheet by, for example, screen printing or gravure printing. The conductive paste for the internal electrodes and the conductive paste for the auxiliary electrodes are printed at intervals in the length direction L. This results in a dielectric sheet for the inner layer portion on which the conductive paste for the internal electrodes and the conductive paste for the auxiliary electrodes are printed.

[0073] As the dielectric sheet for the outer layer portion, a dielectric sheet on which no internal electrode pattern or auxiliary electrode pattern is printed is prepared. Note that the components contained in the dielectric sheet for the inner layer portion and the components contained in the dielectric sheet for the outer layer portion may be different from each other.

[0074] (Laminating Process) Next, the dielectric sheets for the inner layer portions are laminated. When laminating the dielectric sheets for the inner layer portions, a plurality of dielectric sheets on which a conductive paste to become the first internal electrodes and a conductive paste to become the second auxiliary electrodes are printed are laminated in succession, and then a plurality of dielectric sheets on which a conductive paste to become the second internal electrodes and a conductive paste to become the first auxiliary electrodes are printed are laminated in succession. This is repeatedly performed. In this way, the first internal electrode group 16A, the second internal electrode group 16B, the first auxiliary electrode group 22A, and the second auxiliary electrode group 22B are formed.

[0075] Here, the dielectric sheets for the inner layer portions are stacked while being pressed in the stacking direction. The dielectric sheets for the inner layer portions may be pressed when one sheet is stacked, or when multiple sheets are stacked. When the dielectric sheets are pressed, the pressure applied to the portion of the internal electrode to be curved is set to be greater than the pressure applied to other portions. Therefore, the portion of the conductive paste for the internal electrode located in the extension region is curved so as to be convex toward the center of the stacking direction T of the laminate. This forms a curve in the conductive paste for the internal electrode that becomes the inner curved portion 151a. The magnitude of the curve of the inner curved portion 151a can be adjusted by adjusting the magnitude of the pressure applied during pressing.

[0076] When the auxiliary electrode 21 is provided in the inner layer portion 11, the pressed conductive paste for the internal electrode deforms to penetrate into the region between the conductive paste for the internal electrode and the conductive paste for the auxiliary electrode, making it possible to suitably form the inner curved portion 151a without significantly varying the pressure applied to each portion of the conductive paste. Therefore, providing the auxiliary electrode 21 in the inner layer portion 11 makes it possible to easily form the inner curved portion 151a in the internal electrode 15. It also makes it easier to form the inner curved portion 151a in an appropriate position (i.e., the portion located in the extension region 25). However, even if the auxiliary electrode 21 is not provided in the inner layer portion 11, the inner curved portion 151a can be formed in the inner internal electrode 151 by applying a stronger pressure to the desired portion of the conductive paste for the internal electrode compared to other portions during pressing.

[0077] In addition, the outer curved portion 152a is formed, for example, when a dielectric sheet on which a conductive paste that becomes the outer internal electrode 152 is printed is stacked, and the conductive paste and the dielectric sheet are curved along the curvature of the inner curved portion 151a.

[0078] The dielectric sheet constituting the portion of the inner layer portion 11 closer to the first principal surface AA and the dielectric sheet constituting the portion of the inner layer portion 11 closer to the second principal surface AB are, for example, laminated separately and then combined. As a result, it is possible to form a curve that is convex toward the center of the laminate 2 in the stacking direction T in both the inner internal electrode 151 located in the portion of the laminate 2 closer to the first principal surface AA and the inner internal electrode 151 located in the portion of the laminate 2 closer to the second principal surface AB.

[0079] Next, dielectric sheets for outer layers are laminated on both sides of the laminated dielectric sheets for inner layers in the lamination direction. The dielectric sheets for outer layers are thermocompression bonded to the laminated dielectric sheets for inner layers. This results in a mother block. The mother block is pressed in the lamination direction using a means such as a hydrostatic press.

[0080] Each outer layer portion 12 may be formed by laminating a plurality of dielectric sheets, or may be formed by a single dielectric sheet.

[0081] (Mother Block Cutting Process) Next, the mother block is cut along cutting lines corresponding to the dimensions of the laminate 2. The mother block is cut, for example, in the length direction L and the width direction W. This results in multiple rectangular blocks (referred to as "laminated chips"). It is preferable that the corners and ridges of the laminated chips are rounded, for example, by barrel polishing.

[0082] (Laminate Firing Process) Next, the laminated chip is heated at a predetermined firing temperature in a nitrogen atmosphere for a predetermined time. This results in the laminate 2. When the internal electrodes 15 contain Cu as a primary component, Cu has relatively excellent oxidation resistance, so the atmosphere used when co-firing the dielectric layer 14 and the internal electrodes 15 can be set to a more oxidizing side. This suppresses the reduction of Ca(Zr, Ti)O3-based compounds. When perovskite-type compounds such as Ca(Zr, Ti)O3-based compounds are reduced, they may exhibit semiconductor properties and may not exhibit good dielectric properties. However, this suppresses such defects.

[0083] (Base electrode layer forming process) Next, a base electrode layer 31 is formed on each end face C of the laminate 2. A conductive paste containing glass and metal is applied onto the laminate 2. Each base electrode layer 31 is formed, for example, so as to cover each end face C, a portion of each main face A, and a portion of each side face B. However, this is not limited to this, and each base electrode layer 31 may be disposed only on each end face C.

[0084] (Base Electrode Layer Baking Process) Next, the laminate 2 on which the base electrode layer 31 has been formed is heated in a nitrogen atmosphere at a predetermined baking temperature for a predetermined time. This bakes the base electrode layer 31 onto the laminate 2. The laminate baking process and the base electrode layer baking process may be performed simultaneously after the base electrode layer material has been placed on the laminate chip. Furthermore, when the base electrode layer 31 contains Cu as a main component, the baking atmosphere can be set to be more oxidizing. This can prevent the Ca(Zr,Ti)O3-based compound from being reduced.

[0085] (Plating Process) Next, the plating layer 32 is formed on the base electrode layer 31. First, the first plating layer 321 is formed on the base electrode layer 31. Next, the second plating layer 322 is formed on the first plating layer 321. The first plating layer 321 is formed by, for example, Ni plating. The second plating layer 322 is formed by, for example, Sn plating. The first plating layer 321 and the second plating layer 322 are formed sequentially by, for example, electrolytic plating.

[0086] As a result of the above, the multilayer ceramic capacitor 1 shown in FIG. 1 is obtained.

[0087] <Experimental Examples> Examples and Comparative Examples will be described below: Experimental methods and experimental results will be described below.

[0088] 1. Manufacturing of Multilayer Ceramic Capacitors Multilayer ceramic capacitors having the same structure as the above-described multilayer ceramic capacitor 1 (the structure shown in FIGS. 1 to 4) were manufactured as samples for experimental examples and comparative examples. The manufacturing method for the sample multilayer ceramic capacitors was the manufacturing method according to the embodiment described above. The comparative example was Comparative Example 1. The experimental examples were Experimental Examples 1 to 7. For each experimental example and comparative example, 10,000 sample multilayer ceramic capacitors were manufactured.

[0089] In each of the experimental examples and comparative examples, the dimensions of the multilayer ceramic capacitor were L×W×T=0.3 mm×0.6 mm×0.18 mm.

[0090] The magnitude of curvature of the internal electrodes differed between the experimental examples and the comparative examples. The magnitude of curvature of the internal electrodes for each experimental example was adjusted by adjusting the lamination pressure during the lamination process. In the case of the comparative example sample, the lamination pressure during the lamination process was constant at each location of the internal electrodes.

[0091] The magnitude of curvature of the curved portion of the internal electrode for each experimental example and comparative example is as shown in Table 1. The magnitude of curvature of the inner curved portion is sometimes referred to as "TI", and the magnitude of curvature of the outer internal electrode is sometimes referred to as "TO".

[0092] 2. Evaluation Next, the produced samples were measured and evaluated according to the following methods: Measurements were made of the withstand voltage, the degree of curvature of the internal electrodes, and the rate of occurrence of defects in the internal structure.

[0093] <Withstand Voltage> Withstand voltage measurement (DC-BDV test) was carried out under conditions of a voltage rise rate of 100 V / sec and a detection current of 10 mA, and the withstand voltage of each sample was measured.

[0094] For each example and comparative example, 20 samples were randomly selected from 10,000 samples and the withstand voltage was measured. The average of the obtained withstand voltages was taken as the withstand voltage for each example and comparative example.

[0095] For samples to be measured for withstand voltage, other measurements were carried out after the withstand voltage measurement was carried out.

[0096] <Degree of Curvature of Internal Electrode> The degree of curvature of the inner curved portion and the degree of curvature of the outer internal electrode in the internal electrode group closest to the surface of the laminate were measured.

[0097] The LT cross section passing through the center of the multilayer ceramic capacitor in the width direction W was exposed by polishing and observed with an optical microscope. For the internal electrode group closest to the surface of the laminate, the magnitude of curvature of the inner curved portion and the magnitude of curvature of the outer internal electrode were measured according to the definitions described in the description of the above embodiment.

[0098] For each example and comparative example, the magnitude of curvature of the inner curved portion and the magnitude of curvature of the outer internal electrode were measured for 10,000 samples. The average value of the obtained magnitude of curvature of the inner curved portion was used as the magnitude of curvature of the inner curved portion for each example and comparative example. The average value of the obtained magnitude of curvature of the outer internal electrode was used as the magnitude of curvature of the outer internal electrode for each example and comparative example.

[0099] Further, for each example and comparative example, the value obtained by dividing the magnitude of curvature of the inner curved portion by the magnitude of curvature of the outer internal electrode (sometimes referred to as "TI / TO") was calculated.

[0100] <Internal structural defect occurrence rate> An LT cross section passing through the center of the width direction W of the multilayer ceramic capacitor was observed with an optical microscope. The presence or absence of interlayer peeling between the internal electrode group closest to the surface of the laminate and the dielectric layer adjacent to the internal electrode group, and the presence or absence of cracking in the dielectric layer adjacent to the internal electrode group were observed. Samples in which at least either interlayer peeling or cracking was observed were determined to be samples in which internal structural defects had occurred.

[0101] For each of the examples and comparative examples, the number of samples in which internal structural defects occurred was counted for 10,000 samples. The number of samples in which internal structural defects occurred among the 10,000 samples was defined as the "internal structural defect occurrence rate."

[0102] <Determination of Pass / Fail> A determination of pass / fail was carried out for each of the examples and comparative examples.

[0103] When the internal structure defect occurrence rate was 0 / 10000 and the withstand voltage was 800 V or more, the result was judged as "good."

[0104] When the evaluation result was not good, if the internal structural defect occurrence rate was less than 10 / 10000 and the withstand voltage was 800 V or more, the evaluation result was determined to be "generally good."

[0105] When the internal structural defect occurrence rate was 10 / 10,000 or more, the result was judged as "poor."

[0106] 3. Measurement Results Table 1 shows the TI (μm), TO (μm), TI / TO, internal structure defect occurrence rate, withstand voltage (V), and evaluation results for Comparative Example 1 and Experimental Examples 1 to 7.

[0107]

[0108] In Comparative Example 1, the TI was 0.05 μm. In Comparative Example 1, the internal structure defect occurrence rate was 10 / 10,000, and the evaluation result was poor. However, in Comparative Example 1, the withstand voltage was 852 V, which was a good result.

[0109] In Experimental Examples 1 to 7, the TI was 0.1 μm or more and 6 μm or less. In Experimental Examples 1 to 7, the internal structure defect rate was 3 / 10,000 or less, which was a good result. In particular, in Experimental Examples 2 to 7, the internal structure defect rate was 0 / 10,000, which was an even better result.

[0110] In Experimental Examples 2 to 7, the TI / TO was 8.3 or more and 42.9 or less. In the samples of Experimental Examples 2 to 7, the inner internal electrode was relatively greatly curved, and the outer internal electrode was barely curved. It is believed that the relatively greatly curved inner electrode improved the adhesion between the dielectric layer and the inner internal electrode. It is believed that the barely curved outer internal electrode prevented a decrease in the adhesion between the outer internal electrode and the outer layer. It is believed that these factors effectively prevented the occurrence of internal structural defects.

[0111] In Experimental Example 7, TI was 6 μm. In Experimental Example 7, the internal structure defect occurrence rate was 0 / 10,000, which was a good result. However, in Experimental Example 7, the withstand voltage was 793 V, which was a slightly lower value compared to the results of Experimental Examples 1 to 6. In Experimental Example 7, it is thought that the TI became too large, which resulted in the thickness of the dielectric in the vicinity of the curved portion of the inside internal electrode becoming too thin, resulting in a decrease in withstand voltage.

[0112] From the above, as shown by the results of Experimental Examples 2 to 6, it was confirmed that by setting TI to 0.5 μm or more and 3 μm or less, it is possible to suitably suppress the occurrence of internal structural defects and maintain the withstand voltage within a good range. It was also confirmed that by setting TI to 0.5 μm or more and 3 μm or less, a multilayer ceramic capacitor with excellent reliability can be obtained. Furthermore, it was confirmed that by setting TI / TO to 8.3 or more and 28.6 or less, it is possible to more reliably suitably suppress the occurrence of internal structural defects and maintain the withstand voltage within a good range.

[0113] (Effects of the Embodiment) According to the present embodiment, the following effects can be obtained.

[0114] According to the above embodiment, the multilayer ceramic capacitor 1 includes a laminate 2 and a pair of external electrodes 3 arranged on each end face C of the laminate 2 and connected to the internal electrodes 15, the dimension of the laminate 2 in the width direction W being greater than the dimension of the laminate in the length direction L. The multiple internal electrodes 15 include multiple internal electrode groups 16, which are groups of internal electrodes 15 adjacent to each other in the stacking direction T and exposed at the same end face C, and each internal electrode group 16 includes an inner internal electrode 151, which is the internal electrode 15 closest to the center of the laminate 2 in the stacking direction T, among the internal electrodes 15 constituting the internal electrode group 16, and an outer internal electrode, which is the internal electrode closest to the surface of the laminate 2, among the internal electrodes 15 constituting the internal electrode group 16. Of the multiple internal electrode groups 16, the inner internal electrode 151 of the internal electrode group 16 closest to the surface of the laminate 2 has an inner curved portion 151a, which is a portion curved in a shape convex toward the center of the laminate 2 in the stacking direction T.

[0115] With this configuration, the multilayer ceramic capacitor 1 is a so-called LW-reversed multilayer ceramic capacitor, which makes it possible to reduce the ESL of the multilayer ceramic capacitor 1. Furthermore, the LW-reversed multilayer ceramic capacitor 1 can effectively reduce the ESL even in the high frequency range.

[0116] Furthermore, since one internal electrode group 16 is composed of a plurality of internal electrodes 15, it is possible to obtain the same effect as when one internal electrode is made thicker. This makes it possible to reduce the ESR of the internal electrodes 15. In the high frequency range, by reducing the ESR of the internal electrodes 15, it is possible to suitably reduce the ESR of the multilayer ceramic capacitor 1. Therefore, it is possible to suitably reduce the ESR of the multilayer ceramic capacitor 1 in the high frequency range.

[0117] Furthermore, in the periphery of the internal electrode group 16 near the surface of the laminate 2, a step is likely to occur due to the influence of the thickness of the internal electrodes 15, which tends to reduce the adhesion between the dielectric layer 14 and the internal internal electrode 151. However, since the internal internal electrode 151 has the inner curved portion 151a, an anchor effect can be generated between the internal internal electrode 151 and the dielectric layer 14. This can improve the adhesion between the internal internal electrode 151 and the dielectric layer 14. This can suppress the occurrence of cracks, delamination, etc. in the periphery of the internal electrode group 16.

[0118] Therefore, it is possible to provide a multilayer ceramic capacitor 1 that can suppress energy loss in the high frequency range, achieve the effect of reducing ESL, and suppress internal structural defects.

[0119] According to the above embodiment, the inner layer portion 11 includes an auxiliary electrode 21 spaced apart from the internal electrode 15 in the longitudinal direction L, and if the region of the inner layer portion 11 between the internal electrode 15 exposed at one end face C and the auxiliary electrode 21 located between the internal electrode 15 and the other end face C is defined as an extended region in the stacking direction T, then the apex of the inner curved portion 151a is provided in the portion of the inner internal electrode 151 exposed at the other end face C that is located in the extended region 25.

[0120] According to this configuration, the auxiliary electrode 21 is provided in the inner layer portion 11, thereby increasing the proportion of metal in the laminate 2. The toughness of the metal is higher than the toughness of the dielectric layer 14. This improves the mechanical strength of the laminate 2, thereby suppressing the occurrence of cracks in the laminate 2.

[0121] In the extension region 25, the adhesion between the internal electrode 15 and the dielectric layer 14 is weaker than in the portion where the internal electrode groups 16 face each other and in the portion where the internal electrode groups 16 face the auxiliary electrode 21. However, with this configuration, by arranging the inner curved portion 151a in the extension region 25, the adhesion between the inner internal electrode 151 and the dielectric layer 14 can be further improved. This makes it possible to more suitably suppress internal structural defects.

[0122] During pressing in the lamination process, it is possible to suppress curvature of the portion of the internal electrode 15 that faces the auxiliary electrode 21 in the lamination direction T. This makes it possible to suppress curvature near the end of the internal electrode 15 in the length direction L, making it easier to bend the internal electrode 15 into a substantially V-shape or a substantially U-shape.

[0123] According to the above embodiment, in the internal electrode group 16 closest to the surface of the laminate 2 among the multiple internal electrode groups 16, the degree of curvature of the inner curved portion 151a is greater than the degree of curvature of the outer internal electrode 152.

[0124] According to this configuration, by curving the inner internal electrode 151 more greatly, the adhesive strength between the inner internal electrode 151 and the dielectric layer can be improved. Also, if the outer curved portion 152a is curved more greatly toward the center of the laminate 2, the adhesive strength between the outer curved portion 152a and the outer layer portion 12 may be reduced, but this can be prevented. As a result, internal structural defects can be more effectively prevented.

[0125] According to the above embodiment, the degree of curvature of the inner curved portion 151a is 0.5 μm or more and 3 μm or less.

[0126] With this configuration, it is possible to sufficiently suppress energy loss in the high frequency range while suppressing peeling at the interface between the internal electrode 15 and the dielectric layer 14 due to the difference in shrinkage between the internal electrode 15 and the dielectric layer 14 during firing.

[0127] According to the above embodiment, the auxiliary electrode 21 is located on the extension of the internal electrode 15 .

[0128] According to this configuration, an increase in the dimension T of the laminate 2 in the lamination direction due to the thickness of the auxiliary electrode 21 can be suppressed, and therefore the laminated ceramic capacitor 1 can be easily formed thin.

[0129] According to the above embodiment, the internal electrode 15 contains Cu, and the external electrode 3 has the base electrode layer 31 disposed on the surface of the laminate 2, and the base electrode layer 31 contains Cu.

[0130] According to this configuration, Cu has low electrical resistance and low conductor loss due to the conductor, so that the loss of the multilayer ceramic capacitor can be reduced.

[0131] According to the above embodiment, the dielectric layer 14 is made of (Ca １－ｘ－ｙ , Sr ｘ , Ba ｙ ) m(Zr １－ｚ－α , Ti ｚ , Hf α ) O ３ where x is 0 or more and 1 or less, y is 0 or more and 0.4 or less, m is 1.0 or more and 1.1 or less, z is 0 or more and 0.2 or less, and α is 0 or more and 0.3 or less, or is TiO2.

[0132] With this configuration, a multilayer ceramic capacitor with a small temperature coefficient of capacitance and small loss can be obtained.

[0133] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various changes and modifications are possible.

[0134] In the above embodiment, one internal electrode group 16 is composed of two internal electrodes 15, but one internal electrode group may be composed of three or more internal electrodes.

[0135] In the above embodiment, the first outer internal electrode 152A is provided with the first outer curved portion 152Aa, and the second outer internal electrode 152B is provided with the second outer curved portion 152Ba, but the first outer curved portion 152Aa and the second outer curved portion 152Ba are not essential components. In order to prevent a decrease in adhesion between the outer internal electrode and the outer layer portion, it is preferable that the outer internal electrode not be curved toward the center of the stacking direction of the laminate.

[0136] In the above embodiment, the first inner internal electrode 151A has the first inner curved portion 151Aa, and the second inner internal electrode 151B has the second inner curved portion 151Ba, but it is sufficient if at least one of the first inner internal electrode 151A and the second inner internal electrode 151B has an inner curved portion. However, if both the first inner internal electrode 151A and the second inner internal electrode 151B have an inner curved portion, the above-mentioned effects can be more suitably obtained.

[0137] The present invention also includes the following combinations:

[0138] <1> A laminate having an inner layer portion including a plurality of alternately stacked dielectric layers and a plurality of inner electrodes, a pair of main surfaces facing each other in a stacking direction, a pair of side surfaces facing each other in a width direction which is a direction perpendicular to the stacking direction, and a pair of end surfaces facing each other in a length direction which is a direction perpendicular to the stacking direction and the width direction, and an outer electrode arranged on the end surface and connected to the inner electrode, wherein the dimension of the laminate in the width direction is larger than the dimension of the laminate in the length direction, and the plurality of inner electrodes are adjacent to each other in the stacking direction and are connected to the inner electrode exposed on the same end surface. a plurality of internal electrode groups each including an inner internal electrode that is the internal electrode closest to a center of the laminate in the stacking direction among the internal electrodes constituting the internal electrode group, and an outer internal electrode that is the internal electrode closest to a surface of the laminate among the internal electrodes constituting the internal electrode group, and the inner internal electrode of the internal electrode group closest to the surface of the laminate among the plurality of internal electrode groups has an inner curved portion that is a portion curved in a shape that is convex toward the center of the laminate in the stacking direction.

[0139] <2> The multilayer ceramic capacitor according to <1>, wherein the inner layer portion includes an auxiliary electrode provided at a distance from the internal electrode in the length direction, and when a region of the inner layer portion between the internal electrode exposed at one of the end faces and the auxiliary electrode located between the internal electrode and the other end face is defined as an extended region in the stacking direction, a vertex of the inner curved portion is provided in a portion of the inner internal electrode exposed at the other end face located in the extended region.

[0140] <3> The multilayer ceramic capacitor according to <1> or <2>, wherein, in the internal electrode group closest to the surface of the laminate among the plurality of internal electrode groups, the magnitude of curvature of the inner curved portion is larger than the magnitude of curvature of the outer internal electrode.

[0141] <4> The multilayer ceramic capacitor according to any one of <1> to <3>, wherein the magnitude of the curvature of the inner curved portion is 0.5 μm or more and 3 μm or less.

[0142] <5> The multilayer ceramic capacitor according to any one of <2> to <4>, wherein the auxiliary electrodes are present on extensions of the internal electrodes.

[0143] <6> The multilayer ceramic capacitor according to any one of <1> to <5>, wherein the internal electrodes contain Cu, and the external electrodes have a base electrode layer disposed on a surface of the laminate, and the base electrode layer contains Cu.

[0144] <7> The dielectric layer is made of (Ca １－ｘ－ｙ , Sr ｘ , Ba ｙ ) m(Zr １－ｚ－α , Ti ｚ , Hf α ) O ３ wherein x is 0 or more and 1 or less, y is 0 or more and 0.4 or less, m is 1.0 or more and 1.1 or less, z is 0 or more and 0.2 or less, and α is 0 or more and 0.3 or less, or is TiO2.

[0145] REFERENCE SIGNS LIST 1 Multilayer ceramic capacitor 2 Laminate 3 External electrode 14 Dielectric layer 15 Internal electrode 16 Internal electrode group 21 Auxiliary electrode 25 Extension region 31 Base electrode layer 151 Internal internal electrode 151a Internal curved portion 152 External internal electrode A Pair of main surfaces B Pair of side surfaces C Pair of end surfaces

Claims

1. A laminate having an inner layer portion including a plurality of alternately stacked dielectric layers and a plurality of internal electrodes, a pair of main surfaces opposing each other in the stacking direction, a pair of side surfaces opposing each other in the width direction which is a direction perpendicular to the stacking direction, and a pair of end faces opposing each other in the length direction which is a direction perpendicular to the stacking direction and the width direction; and external electrodes arranged on the end faces and connected to the internal electrodes, wherein the width direction dimension of the laminate is greater than the length direction dimension of the laminate, and the plurality of internal electrodes have a plurality of internal electrode groups which are groups consisting of internal electrodes that are adjacent to each other in the stacking direction and exposed on the same end face, and each internal electrode group has an inner internal electrode which is the internal electrode closest to the center of the laminate in the stacking direction among the internal electrodes constituting the internal electrode group, and an outer internal electrode which is the internal electrode closest to the surface of the laminate among the internal electrodes constituting the internal electrode group, a multilayer ceramic capacitor, wherein, among the plurality of internal electrode groups, the inner internal electrode of the internal electrode group closest to the surface of the laminate has an inner curved portion that is curved in a shape that is convex toward a center portion of the laminate in the stacking direction.

2. The multilayer ceramic capacitor according to claim 1, wherein the inner layer portion includes an auxiliary electrode spaced apart from the inner electrode in the longitudinal direction, and when a region of the inner layer portion between the inner electrode exposed at one end face and the auxiliary electrode located between the inner electrode and the other end face is defined as an extended region in the stacking direction, the apex of the inner curved portion is provided in a portion of the inner inner electrode exposed at the other end face that is located in the extended region.

3. A multilayer ceramic capacitor according to claim 1 or 2, wherein, in the internal electrode group closest to the surface of the laminate among the plurality of internal electrode groups, the magnitude of curvature of the inner curved portion is greater than the magnitude of curvature of the outer internal electrode.

4. A multilayer ceramic capacitor according to any one of claims 1 to 3, wherein the magnitude of the curvature of the inner curved portion is 0.5 μm or more and 3 μm or less.

5. A multilayer ceramic capacitor according to any one of claims 2 to 4, wherein the auxiliary electrodes are present on the extensions of the internal electrodes.

6. The multilayer ceramic capacitor according to any one of claims 1 to 5, wherein the internal electrodes contain Cu, the external electrodes have a base electrode layer disposed on the surface of the laminate, and the base electrode layer contains Cu.

7. The dielectric layer is (Ca １－ｘ－ｙ , Sr ｘ , Ba ｙ ) m(Zr １－ｚ－α , Ti ｚ , Hf α ) O ３ wherein x is 0 or more and 1 or less, y is 0 or more and 0.4 or less, m is 1.0 or more and 1.1 or less, z is 0 or more and 0.2 or less, and α is 0 or more and 0.3 or less, or is TiO2.

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