Multilayer ceramic capacitor

Abstract

Provided is a multilayer ceramic capacitor capable of suppressing interlayer peeling. A laminated ceramic capacitor (1) is provided with a laminated body (2) having an inner layer section (11) including dielectric layers (14) and internal electrodes (15) that are alternately laminated. When a cross-section parallel to the lamination direction (T) and the longitudinal direction (L) and passing through a central portion of the laminated ceramic capacitor (1) in the width direction (W) is defined as a reference cross-section (S), the internal electrode (15) has an arc-shaped convex portion that forms a convex arc toward the adjacent dielectric layer (14) in the reference cross-section (S).

Description

Technical Field

[0001] The present utility model relates to a multilayer ceramic capacitor. Background Art

[0002] In the past, in multilayer ceramic capacitors, miniaturization and high capacitance have been required. Therefore, attempts have been made to thin and laminate dielectric layers and internal electrode layers. In addition, in multilayer ceramic capacitors, improvement in reliability has also been required.

[0003] For example, in the multilayer ceramic capacitor of Patent Document 1, a covering layer is disposed between layers of the external electrode. Thereby, improvement in moisture resistance reliability of the multilayer ceramic capacitor has been achieved.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2023 - 117364 Summary of the Utility Model

[0007] Problems to be Solved by the Utility Model

[0008] However, there is a problem that suppression of interlayer peeling inside the laminate is insufficient.

[0009] An object of the present utility model is to provide a multilayer ceramic capacitor capable of suppressing interlayer peeling.

[0010] Means for Solving the Problems

[0011] To solve the above problems, the multilayer ceramic capacitor of the present utility model includes: a laminate having an inner layer portion including alternately laminated dielectric layers and internal electrodes, a pair of outer layer portions disposed sandwiching the inner layer portion in the lamination direction, a pair of main surfaces facing each other in the lamination direction, a pair of side surfaces facing each other in a width direction orthogonal to the lamination direction, and a pair of end surfaces facing each other in a length direction orthogonal to the lamination direction and the width direction; and external electrodes disposed in pairs on at least any one of each of the side surfaces and each of the end surfaces, characterized in that when a cross-section parallel to the lamination direction and the length direction is set as an LT cross-section, in the LT cross-section view, the internal electrode has an arc-shaped convex portion that depicts a convex arc toward the adjacent dielectric layer side.

[0012] Effects of the Utility Model

[0013] According to the present utility model, it is possible to provide a multilayer ceramic capacitor capable of suppressing interlayer peeling. Brief Description of the Drawings

[0014] Figure 1It is a schematic perspective view of the multilayer ceramic capacitor 1 of the embodiment.

[0015] Figure 2 It is Figure 1 the II-II sectional view.

[0016] Figure 3 It is Figure 2 the enlarged view of part III.

[0017] Figure 4 It is Figure 2 the enlarged view of part IV.

[0018] Explanation of reference numerals

[0019] 1 Multilayer ceramic capacitor;

[0020] 2 Stacked body;

[0021] 3 External electrode;

[0022] 11 Inner layer part;

[0023] 12 Outer layer part;

[0024] 14 Dielectric layer;

[0025] 15 Internal electrode;

[0026] 21 Conductive particles;

[0027] 22 Arc-shaped convex part;

[0028] 23 Bulging part;

[0029] 25 Dielectric particles;

[0030] 26 Arc-shaped concave part;

[0031] 28 Interface;

[0032] A A pair of main surfaces;

[0033] B A pair of side surfaces;

[0034] C A pair of end surfaces;

[0035] r1 The radius of curvature of the arc of the arc-shaped convex part;

[0036] S Reference section (LT section). Detailed implementation mode

[0037] Hereinafter, the multilayer ceramic capacitor 1 of the embodiment of the present invention will be described with reference to the drawings.

[0038] (Multilayer ceramic capacitor 1)

[0039] AsFigure 1 As shown in the figure, the multilayer ceramic capacitor 1 has a substantially rectangular parallelepiped shape. The multilayer ceramic capacitor 1 includes a laminate 2 and a pair of external electrodes 3 provided at both ends of the laminate 2. The laminate 2 includes an inner layer portion 11 in which a dielectric layer 14 and an internal electrode 15 are laminated. The laminate 2 has a substantially rectangular parallelepiped shape and has six outer surfaces.

[0040] In this specification, the direction in which the dielectric layer 14 and the internal electrode 15 are laminated in the multilayer ceramic capacitor 1 is defined as the lamination direction T. The direction orthogonal to the lamination direction T and in which a pair of external electrodes 3 are arranged is defined as the length direction L. The direction orthogonal to both the length direction L and the lamination direction T is defined as the width direction W.

[0041] In addition, a cross-section parallel to the lamination direction T and the length direction L and passing through the central portion of the width direction W of the multilayer ceramic capacitor 1 is defined as a "reference cross-section S". It should be noted that Figure 2 the cross-section of shows the reference cross-section S. The reference cross-section S corresponds to an "LT cross-section".

[0042] In the following description, one pair of outer surfaces provided on both sides in the lamination direction T among the six outer surfaces of the laminate 2 are defined as a first main surface AA and a second main surface AB, one pair of outer surfaces extending in the lamination direction T and provided on both sides in the width direction W are defined as a first side surface BA and a second side surface BB, and one pair of outer surfaces extending in the lamination direction T and provided on both sides in the length direction L are defined as a first end surface CA and a second end surface CB. When there is no need to specifically distinguish, the first main surface AA and the second main surface AB are sometimes collectively referred to as "each main surface A". The first side surface BA and the second side surface BB are sometimes collectively referred to as "each side surface B". The first end surface CA and the second end surface CB are sometimes collectively referred to as "each end surface C".

[0043] (Laminate 2)

[0044] The laminate 2 has an inner layer portion 11 and a pair of outer layer portions 12 arranged sandwiching the inner layer portion 11 in the lamination direction T. The laminate 2 as a whole has a substantially rectangular parallelepiped shape. The laminate 2 preferably has roundness at the corner portions and the ridge line portions. It should be noted that the corner portion is the part where three faces of the laminate intersect, and the ridge line portion is the part where two faces of the laminate intersect.

[0045] (Inner layer portion 11)

[0046] As Figure 2 shown, 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 laminated.

[0047] The dielectric layer 14 is formed of a dielectric ceramic mainly composed of BaTiO3, for example. The dielectric ceramic may also include Mn compounds, Fe compounds, Cr compounds, Co compounds, Ni compounds, etc. as sub-components.

[0048] The internal electrode 15 is formed of a metal material such as Ni, Cu, Ag, Pd, Ag-Pd alloy, Au, etc., for example. The internal electrode 15 has a first internal electrode 15A exposed only on the first end face CA and a second internal electrode 15B exposed only on the second end face CB.

[0049] The first internal electrode 15A and the second internal electrode 15B are alternately arranged. The portion of the first internal electrode 15A facing the adjacent second internal electrode 15B is defined as the first facing portion 15Aa. The portion of the second internal electrode 15B facing the adjacent first internal electrode 15A is defined as the second facing portion 15Ba.

[0050] It should be noted that, when there is no need for special distinction, the first internal electrode 15A and the second internal electrode 15B are sometimes collectively referred to as the "internal electrode 15". The first facing portion 15Aa and the second facing portion 15Ba are sometimes collectively referred to as the "facing portion 15a".

[0051] (Outer layer portion 12)

[0052] The outer layer portion 12 is made of the same material as the dielectric layer 14 of the inner layer portion 11. It should be noted that no internal electrode 15 is arranged in the outer layer portion 12.

[0053] (External electrode 3)

[0054] The external electrodes 3 are respectively arranged on each end face C. Either the first internal electrode 15A or the second internal electrode 15B is connected to each external electrode 3. The external electrodes 3 cover not only each end face C but also a part of each main face A and a part of each side face B.

[0055] The external electrode 3 includes a base electrode layer 31 formed in contact with the surface of the laminate 2, a first plating layer 32 arranged on the base electrode layer 31, and a second plating layer 33 arranged on the first plating layer 32.

[0056] The base electrode layer 31 is, for example, a baked layer including a conductive metal such as Cu (copper) and glass. The first plating layer 32 is, for example, a Ni (nickel) plating layer. The second plating layer 33 is, for example, a Sn (tin) plating layer.

[0057] Here, the internal electrode 15 has an arc-shaped convex portion 22 that depicts a convex arc toward the adjacent dielectric layer 14 side. Figure 3 is Figure 2The enlarged view of part III is an enlarged cross-sectional view based on a scanning electron microscope (SEM) photograph. Figure 4 is Figure 2 The enlarged view of part IV is an enlarged cross-sectional view based on an SEM photograph.

[0058] As Figure 3 shown, the arc-shaped convex portion 22 has an arc-shaped convex portion 22A and an arc-shaped convex portion 22B that depict a convex arc toward the first main surface AA side, and an arc-shaped convex portion 22C that depicts a convex arc toward the second main surface AB side. The arc-shaped convex portion 22A, the arc-shaped convex portion 22B, and the arc-shaped convex portion 22C are formed on the same internal electrode 15. This internal electrode 15 is sometimes referred to as "internal electrode 151". It should be noted that the internal electrode 151 is located in a region near the central portion in the stacking direction T of the inner layer portion 11.

[0059] The arc-shaped convex portion 22A and the arc-shaped convex portion 22B are formed on the surface of the internal electrode 151 on the first main surface AA side, and are arranged in sequence from the first end face CA side toward the second end face CB side.

[0060] The arc-shaped convex portion 22C is formed on the surface of the internal electrode 151 on the second main surface AB side. In the reference cross-section S, the positions in the length direction L of both ends of the length direction L of the arc-shaped convex portion 22A and the positions in the length direction L of both ends of the length direction L of the arc-shaped convex portion 22C are aligned respectively. In this case, the internal electrode 151 has an expansion portion 231, and the expansion portion 231 has the arc-shaped convex portion 22A and the arc-shaped convex portion 22C and expands in two directions in the stacking direction T. The outer shape of the expansion portion 231 in the reference cross-section S is substantially elliptical extending along the length direction L.

[0061] It should be noted that the situation of "the positions in the length direction L being aligned" mentioned in this specification means that the separation distance in the length direction L is equal to or less than the average particle diameter of the conductive particles 21 described later, and is not limited to the case where the positions in the length direction L are the same.

[0062] The dielectric layer 14 has an arc-shaped concave portion 26, and the arc-shaped concave portion 26 is recessed toward the inner side of the dielectric layer 14 to depict an arc.

[0063] The arc-shaped concave portion 26 has an arc-shaped concave portion 26A and an arc-shaped concave portion 26B that depict a concave arc toward the second main surface AB side, and an arc-shaped concave portion 26C that depicts a concave arc toward the first main surface AA side.

[0064] The arc-shaped concave portion 26A and the arc-shaped concave portion 26B are formed in the same dielectric layer 14, and are arranged in sequence from the first end face CA side toward the second end face CB side. This dielectric layer 14 is sometimes referred to as "dielectric layer 141". The dielectric layer 141 is adjacent to the first main surface AA side of the internal electrode 151.

[0065] The arcuate concave portion 26C is formed in the dielectric layer 14 adjacent to the second main surface AB side of the internal electrode 151, that is, the dielectric layer 142. It should be noted that the internal electrode 151 is sandwiched between the dielectric layer 141 and the dielectric layer 142.

[0066] The arcuate convex portion 22A enters the concave portion of the arcuate concave portion 26A. Specifically, the arcuate convex portion 22A forms an interface 28A in close contact with the arcuate concave portion 26A. The arcuate convex portion 22B enters the concave portion of the arcuate concave portion 26B. Specifically, the arcuate convex portion 22B forms an interface 28B in close contact with the arcuate concave portion 26B. The arcuate convex portion 22C enters the concave portion of the arcuate concave portion 26C. Specifically, the arcuate convex portion 22C forms an interface 28C in close contact with the arcuate concave portion 26C.

[0067] Thereby, the coupling force between the dielectric layer 14 and the internal electrode 15 can be improved, and the peeling between the dielectric layer 14 and the internal electrode 15 can be suppressed. It should be noted that in Figure 3 the interface 28A, the interface 28B, and the interface 28C are shown by imaginary lines.

[0068] In addition, when there is an arcuate convex portion 22 protruding in one direction in the stacking direction T and an arcuate convex portion 22 protruding in the other direction in the stacking direction T, and the portion expanding in both directions in the stacking direction T of the internal electrode 15 is defined as the expansion portion 23, the internal electrode 151 has an expansion portion 231 including the arcuate convex portion 22A protruding toward the first main surface AA side and the arcuate convex portion 22C protruding toward the second main surface AB side. The positions in the length direction L of the respective ends of the length direction L of the arcuate convex portion 22A and the respective ends of the length direction of the arcuate convex portion 22C are aligned. Thereby, the coupling force between the internal electrode 151 and the dielectric layers 14 on both sides of the internal electrode 151 in the stacking direction T can be improved, and thus, the peeling between the dielectric layer 14 and the internal electrode 15 can be appropriately suppressed.

[0069] It should be noted that in one internal electrode 15, it is preferable that a plurality of expansion portions 23 are continuously formed in the length direction L. Thereby, the peeling between the dielectric layer 14 and the internal electrode 15 can be more appropriately suppressed.

[0070] In addition, when adjacent internal electrodes 15 both have a plurality of expansion portions 23 continuously formed in the length direction L, it is preferable that the positions in the length direction L of the respective ends of the length direction L of the expansion portions 23 formed in one of the adjacent internal electrodes 15 are different from the positions in the length direction L of the respective ends of the length direction L of the expansion portions 23 formed in the other internal electrode 15. Thereby, the peeling between the dielectric layer 14 and the internal electrode 15 can be more appropriately suppressed.

[0071] It should be noted that in this specification, the case where "a plurality of arc-shaped convex portions are continuously formed" refers to either the case where the conductive particles (described later) at the end of the length direction L of one of the two adjacent arc-shaped convex portions in the length direction L are the same conductive particles as those at the end of the length direction L of the other arc-shaped convex portion, or the case where they are two adjacent conductive particles.

[0072] In the inner layer portion 11, the regions where the arc-shaped convex portions 22 and the arc-shaped concave portions 26 are located are not particularly limited.

[0073] For example, as Figure 4 shown, the arc-shaped convex portion 22 has an arc-shaped convex portion 22D that depicts a convex arc toward the second main surface AB side. The arc-shaped convex portion 22D is formed on the internal electrode 153, which is a different internal electrode 15 from the internal electrode 15 on which the arc-shaped convex portions 22A and 22B are formed. The internal electrode 153 is located in a region near the end of the first main surface AA side of the inner layer portion 11.

[0074] The arc-shaped concave portion 26 has an arc-shaped concave portion 26D that depicts a concave arc toward the first main surface AA side. The arc-shaped concave portion 26D is formed on the dielectric layer 144, which is a different dielectric layer 14 from the dielectric layer 14 on which the arc-shaped concave portions 26A, 26B, and 26C are formed. The dielectric layer 144 is adjacent to the second main surface AB side of the internal electrode 153.

[0075] The arc-shaped convex portion 22D enters the concave portion of the arc-shaped concave portion 26D. Specifically, the arc-shaped convex portion 22D and the arc-shaped concave portion 26D are formed in close contact to form an interface 28D. The interface 28D is shown by a phantom line in Figure 4 this figure.

[0076] It should be noted that the interfaces 28A, 28B, 28C, and 28D are sometimes collectively referred to as "interface 28".

[0077] The internal electrode 15 has a plurality of conductive particles 21.

[0078] The number of conductive particles 21 arranged in the stacking direction T in one internal electrode 15 is defined as the number of the first longitudinal rows. Regarding the number of the first longitudinal rows, for example, in the SEM photograph of the reference cross-section S (described in detail later), one internal electrode 15 is divided into six equal parts along the length direction L, and the number of the first longitudinal rows is measured at the five boundaries of the six equal parts, and the number of the first longitudinal rows is the average value thereof. It should be noted that the number of the first longitudinal rows corresponds to the "number of longitudinal rows" mentioned in the claims.

[0079] The number of the first vertical rows is preferably 3 or more, more preferably 4 or more. Thus, the coverage rate of the internal electrode 15 with respect to the dielectric layer 14 can be increased.

[0080] The surface of the arc-shaped convex portion 22 is formed by arranging conductive particles 21 in a number equal to or more than the number of the first vertical rows of the internal electrode 15 in which the arc-shaped convex portion 22 is formed so as to depict an arc. Thus, a smooth arc-shaped convex portion can be formed, and accordingly, delamination between layers can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0081] The surface of the arc-shaped convex portion 22 is preferably formed by arranging 5 or more conductive particles so as to depict an arc, and more preferably formed by arranging 5 or more and 15 or less conductive particles so as to depict an arc. Thus, a smooth arc-shaped convex portion 22 can be formed, and accordingly, delamination between layers can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0082] The dimension of the arc-shaped convex portion 22 in the length direction L is larger than the dimension of the internal electrode 15 in the stacking direction T in which the arc-shaped convex portion 22 is formed. Thus, a smooth arc-shaped convex portion can be formed, and accordingly, delamination between layers can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0083] In the reference cross-section S1, a straight line parallel to the length direction L passing through the end portion of the arc-shaped convex portion 22 located on the side opposite to the protruding direction of the arc-shaped convex portion 22 among the two end portions in the length direction L of the arc-shaped convex portion 22 is defined as the first reference line.

[0084] Regarding the "dimension of the arc-shaped convex portion 22 in the length direction L", two points having the same position in the length direction L of each end portion of the arc-shaped convex portion 22 on the first reference line in the reference cross-section S are taken, and the "dimension of the arc-shaped convex portion 22 in the length direction L" is the separation distance between the two points.

[0085] Regarding the dimension of the internal electrode 15 in the stacking direction T, for example, in the SEM photograph of the reference cross-section S (described in detail later), one internal electrode 15 is divided into six equal parts along the length direction L, and the dimensions of the internal electrode 15 in the stacking direction T are measured at the five boundaries of the divided regions, and the dimension of the internal electrode 15 in the stacking direction T is the average value thereof.

[0086] The dimension of the arc-shaped convex portion 22 in the stacking direction T is larger than the average particle diameter of the conductive particles 21 in the internal electrode 15 in which the arc-shaped convex portion 22 is formed. Thus, delamination between layers can be more appropriately suppressed.

[0087] The average particle diameter of the conductive particles 21 is preferably 0.1 μm or more and 0.3 μm or less.

[0088] The "dimension in the stacking direction T of the arcuate convex portion 22" is the separation distance in the stacking direction T between the most protruding portion of the surface of the arcuate convex portion 22 in the stacking direction T and the first reference line in the reference cross-section S.

[0089] In addition, the "average particle diameter" as described in this specification is the median diameter in the area particle size distribution, and is the area equivalent diameter at which the cumulative value in the cumulative distribution of the area equivalent diameters of a plurality of particles becomes 50%. In other words, the average particle diameter is the area equivalent diameter at which, when a plurality of particles are divided into two based on a certain area equivalent diameter, the number of particles larger than the reference and the number of particles smaller than the reference become the same number.

[0090] The radius of curvature of the arc of the arcuate convex portion 22 (sometimes referred to as "radius of curvature r1") is preferably 1 μm or more and 3 μm or less. The radius of curvature of the arc of the arcuate convex portion 22 is preferably 1 time or more and 5 times or less the dimension in the stacking direction T of the internal electrode 15 on which the arcuate convex portion 22 is formed. Thereby, interlayer peeling can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed. It should be noted that the radius of curvature r1 of the arcuate convex portion 22 can be obtained as the radius of curvature of a circle passing through both end portions in the length direction L of the arcuate convex portion 22 and the point on the surface of the arcuate convex portion 22 that protrudes most toward the adjacent dielectric layer 14 side.

[0091] In addition, the dielectric layer 14 includes a plurality of dielectric particles 25.

[0092] The number of dielectric particles 25 arranged in the stacking direction T in the portion of one dielectric layer 14 sandwiched by the adjacent opposing portions 15a is defined as the second longitudinal row number. Regarding the second longitudinal row number, for example, in a scanning electron microscope (SEM) photograph of the reference cross-section S (described in detail later), the portion of one dielectric layer 14 sandwiched by the adjacent opposing portions 15a is equally divided into six in the length direction L, and at the five boundaries of the equally divided regions, the number of dielectric particles 25 arranged in the stacking direction T is measured respectively, and the second longitudinal row number is the average value thereof.

[0093] The surface of the arcuate concave portion 26 is formed by arranging dielectric particles 25 in an amount of more than half of the second longitudinal row number of the dielectric layer 14 in which the arcuate concave portion 26 is formed so as to depict an arc. Thereby, a smooth arcuate concave portion 26 can be formed, and thus, interlayer peeling can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed. The second longitudinal row number is preferably 4 or more, and more preferably 5 or more.

[0094] The surface of the arc-shaped recess 26 is preferably formed by arranging five or more dielectric particles 25 to depict an arc, and more preferably formed by arranging five or more and fifteen or less dielectric particles 25 to depict an arc. Thereby, a smooth arc-shaped recess 26 can be formed, and thus, delamination between layers can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0095] The dimension of the arc-shaped recess 26 in the length direction L is larger than half of the dimension of the dielectric layer 14 in the stacking direction T in which the arc-shaped recess 26 is formed. Thereby, a smooth arc-shaped recess 26 can be formed, and thus, delamination between layers can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0096] It should be noted that in the reference cross-section S1, a straight line that passes through the end portion of the arc-shaped recess 26 in the length direction L that is more located on the side opposite to the recess direction of the arc-shaped recess 26 and extends parallel to the length direction L is defined as the second reference line.

[0097] Regarding the "dimension of the arc-shaped recess 26 in the length direction L", two points on the second reference line in the reference cross-section S where the positions of the end portions of the arc-shaped recess 26 in the length direction L are the same as the position of the length direction L are taken, and the "dimension of the arc-shaped recess 26 in the length direction L" is the separation distance between these two points.

[0098] In addition, regarding the dimension of the dielectric layer 14 in the stacking direction T, for example, in the SEM photograph of the reference cross-section S (described in detail later), a part of the dielectric layer 14 sandwiched between the adjacent opposing portions 15a is equally divided into six parts in the length direction L, and the dimensions of the dielectric layer 14 in the stacking direction T are measured at the five boundaries of the equally divided region, and the dimension of the dielectric layer 14 in the stacking direction T is the average value thereof.

[0099] The dimension of the arc-shaped recess 26 in the stacking direction T is larger than the average particle diameter of the dielectric particles 25 in the dielectric layer 14 in which the arc-shaped recess 26 is formed. Thereby, delamination between layers can be more appropriately suppressed.

[0100] The average particle diameter of the dielectric particles 25 is preferably 0.1 μm or more and 0.3 μm or less.

[0101] The radius of curvature of the arc of the arcuate recess 26 (sometimes referred to as "radius of curvature r2") is preferably 1 μm or more and 3 μm or less. The radius of curvature r2 of the arc of the arcuate recess 26 is preferably 1 / 2 times or more and 2.5 times or less the dimension in the stacking direction T of the dielectric layer 14 in which the arcuate recess 26 is formed. Thereby, interlayer peeling can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed. Note that the radius of curvature r2 of the arcuate recess 26 can be obtained as the radius of curvature of a circle passing through both end portions in the length direction L of the arcuate recess 26 and the point on the surface of the arcuate recess 26 that is most recessed toward the inside of the dielectric layer 14.

[0102] In Figure 3 , the radius of curvature of the arc of the arcuate convex portion 22A is denoted as the radius of curvature r1A, and the radius of curvature of the arc of the arcuate recess 26A is denoted as the radius of curvature r2A. The radius of curvature r1A and the radius of curvature r2A are substantially the same. Similarly, the radius of curvature of the arc of the arcuate convex portion 22B is denoted as the radius of curvature r1B, and the radius of curvature of the arc of the arcuate recess 26B is denoted as the radius of curvature r2B. The radius of curvature r1B and the radius of curvature r2B are substantially the same. In Figure 4 as well, the radius of curvature of the arc of the arcuate convex portion 22D is denoted as the radius of curvature r1D, and the radius of curvature of the arc of the arcuate recess 26D is denoted as the radius of curvature r2D. The radius of curvature r1D and the radius of curvature r2D are substantially the same. Note that, for convenience, illustration of the radius of curvature of the arc of the arcuate convex portion 22C and the radius of curvature of the arc of the arcuate recess 26C is omitted.

[0103] (Measurement method)

[0104] Next, the measurement method for each value will be described.

[0105] First, the multilayer ceramic capacitor 1 is polished to the central position in the width direction W. Thereby, the reference cross section S is exposed.

[0106] Next, the reference cross section S is observed with a microscope to measure each value. The dimension in the stacking direction T of the internal electrode 15, the dimension in the length direction L of the arcuate convex portion 22, the dimension in the stacking direction and the radius of curvature, the number of the first longitudinal rows, the dimension in the length direction L of the arcuate recess 26, the dimension in the stacking direction and the radius of curvature, and the number of the second longitudinal rows can be measured by observing the reference cross section S in a scanning electron microscope (SEM) photograph.

[0107] The average particle diameters of the conductive particles 21 and the dielectric particles 25 can be obtained by taking an SEM photograph of the reference cross section S at a magnification of 10,000 times and using image processing software. In the SEM photograph, the SEM photograph can be binarized with a prescribed threshold value and only the crystal grains can be extracted, and their particle diameters (equivalent circle diameters of areas) can be evaluated.

[0108] (Manufacturing method of multilayer ceramic capacitor 1)

[0109] Next, the manufacturing method of the two-layer multilayer ceramic capacitor 1 of the embodiment will be described.

[0110] First, a green sheet for lamination in which a ceramic slurry is formed into a sheet shape is prepared. A pattern of the internal electrode 15 is printed on the green sheet using a conductive paste. Thus, a green sheet for lamination is obtained. At this time, by further increasing the viscosity of the conductive paste, unevenness can be easily formed on the surface of the internal electrode 15. By adjusting the coating amount of the conductive paste, the dimension in the lamination direction T of the internal electrode 15 can be adjusted.

[0111] The green sheets for lamination are laminated such that the internal electrode patterns are offset by half a pitch in the length direction L between adjacent raw material sheets. On both sides in the lamination direction T of the laminated green sheets for lamination, green sheets for outer layer portions 12 that become the outer layer portions are laminated respectively. The green sheets for outer layer portions are thermocompression-bonded to the green sheets for lamination. Thus, a mother block is obtained.

[0112] The mother block is divided along a cutting line corresponding to the size of the laminate. Thus, a plurality of laminated chips are obtained. It should be noted that the laminated chips preferably have roundness at the corners and ridges by barrel polishing.

[0113] The laminated chips are heated in a nitrogen atmosphere at a prescribed firing temperature for a prescribed time. Thus, the ceramic material and metal material contained in the laminated chips are fired to obtain a laminate 2. At the time of sintering, particles grow in the dielectric layer 14 and the internal electrode 15. Thus, dielectric particles 25 and conductive particles 21 are formed.

[0114] At the time of sintering, preferably within the range where the laminate 2 is sufficiently densified, the firing temperature is set lower and the heating time is set shorter. Thus, melting of the conductive particles 21 and the dielectric particles 25 can be suppressed, and therefore, a decrease in the number of the conductive particles 21 and the dielectric particles 25 can be suppressed.

[0115] In addition, it is preferable to add sub-components containing elements such as silicon (Si) and magnesium (Mg) to the dielectric raw materials constituting the green sheets for lamination and the green sheets for outer layer portions for lamination. For example, Si acts as a grain growth promoter, and Mg acts as a grain growth inhibitor. Therefore, by adjusting the types and addition amounts of the elements added as sub-components to the dielectric raw materials, the particle diameter of the dielectric particles 25 can be adjusted.

[0116] External electrodes 3 are formed on the respective end faces C of the laminate 2. First, a base electrode layer 31 is formed. The base electrode layer 31 is formed so as to cover not only the end face C but also a part of the main face A and the end face C side of the side face B. The base electrode layer 31 is formed, for example, by applying a conductive paste containing a conductive metal and glass to the respective end faces C of the laminate 2 and firing it. A first plating layer 32 is formed on the base electrode layer 31. A second plating layer 33 is formed on the first plating layer 32. The first plating layer 32 and the second plating layer 33 are formed, for example, by an electrolytic plating method.

[0117] Through the above, the multilayer ceramic capacitor 1 is obtained.

[0118] (Effects of the Embodiment)

[0119] According to the present embodiment, the following effects can be obtained.

[0120] According to the present embodiment, in the reference cross-section S, the internal electrode 15 has an arcuate convex portion 22 that depicts a convex arc toward the adjacent dielectric layer 14 side.

[0121] Thereby, the coupling force between the dielectric layer 14 and the internal electrode 15 can be improved, and the peeling between the dielectric layer 14 and the internal electrode 15 can be suppressed.

[0122] According to the present embodiment, the dielectric layer 14 has an arcuate concave portion 26 that is recessed toward the inside of the dielectric layer 14 and depicts an arc, and the arcuate concave portion 26 and the arcuate convex portion 22 of the internal electrode 15 are in close contact to form an interface 28.

[0123] Thereby, interlayer peeling can be more appropriately suppressed.

[0124] According to the present embodiment, the internal electrode 15 has a plurality of conductive particles 21, and the dielectric layer 14 has a plurality of dielectric particles 25.

[0125] Thereby, the arcuate convex portion 22 and the arcuate concave portion 26 can be appropriately formed.

[0126] According to the present embodiment, the number of the first vertical rows is three or more.

[0127] Thereby, the coverage rate of the internal electrode 15 with respect to the dielectric layer 14 can be improved.

[0128] According to the present embodiment, the surface of the arcuate convex portion 22 is preferably formed by arranging conductive particles 21 in a number equal to or more than the number of the first vertical rows of the internal electrode 15 having the arcuate convex portion 22 so as to depict an arc.

[0129] Thereby, a smooth arcuate convex portion 22 can be formed, and thus, interlayer peeling can be suppressed and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0130] According to the present embodiment, the surface of the arc-shaped convex portion 22 is preferably formed by arranging five or more conductive particles 21 to depict an arc.

[0131] Thereby, a smooth arc-shaped convex portion 22 can be formed, and thus, delamination between layers can be suppressed, and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0132] According to the present embodiment, the dimension of the arc-shaped convex portion 22 in the length direction L is preferably larger than the dimension of the internal electrode 15 in the stacking direction T where the arc-shaped convex portion 22 is formed.

[0133] Thereby, a smooth arc-shaped convex portion 22 can be formed, and thus, delamination between layers can be suppressed, and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0134] According to the present embodiment, the dimension of the arc-shaped convex portion 22 in the stacking direction T is preferably larger than the average particle diameter of the conductive particles 21 in the internal electrode 15 where the arc-shaped convex portion 22 is formed.

[0135] Thereby, delamination between layers can be more appropriately suppressed.

[0136] According to the present embodiment, the radius of curvature r1 of the arc of the arc-shaped convex portion 22 is preferably 1 μm or more and 3 μm or less.

[0137] Thereby, delamination between layers can be suppressed, and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0138] According to the present embodiment, the radius of curvature r1 of the arc of the arc-shaped convex portion 22 is preferably 2 times or more and 5 times or less the dimension of the internal electrode 15 in the stacking direction T where the arc-shaped convex portion 22 is formed.

[0139] Thereby, delamination between layers can be suppressed, and the occurrence of local electrolytic concentration and stress concentration can be suppressed.

[0140] According to the present embodiment, the internal electrode 151 has an expansion portion 231 that expands in two directions in the stacking direction T. The expansion portion 231 has an arc-shaped convex portion 22A that protrudes toward the first main surface AA side and an arc-shaped convex portion 22C that protrudes toward the second main surface AB side. The positions of the respective end portions in the length direction L of the arc-shaped convex portion 22A and the respective end portions in the length direction of the arc-shaped convex portion 22C are aligned in the length direction L.

[0141] Thereby, the coupling force between the internal electrode 151 and the dielectric layers 14 located on both sides of the internal electrode 151 in the stacking direction T can be improved, and thus, the peeling between the dielectric layer 14 and the internal electrode 15 can be appropriately suppressed.

[0142] It should be noted that in one internal electrode 15, it is preferable to continuously form a plurality of expansion portions 23 in the length direction L.

[0143] Accordingly, peeling between the dielectric layer 14 and the internal electrode 15 can be more appropriately suppressed.

[0144] In addition, in the case where the adjacent internal electrodes 15 each have a plurality of bulging portions 23 formed continuously in the length direction L, it is preferable that the positions in the length direction L of the respective end portions in the length direction L of the bulging portions 23 formed in one of the adjacent internal electrodes 15 and the positions in the length direction L of the respective end portions in the length direction L of the bulging portions 23 formed in the other internal electrode 15 are different from each other.

[0145] Accordingly, peeling between the dielectric layer 14 and the internal electrode 15 can be more appropriately suppressed.

[0146] As described above, the embodiments of the present invention have been described, but the present invention is not limited to the above embodiments, and various changes and modifications can be made.

[0147] According to the above embodiment, the LT cross-section is a cross-section (reference cross-section S) parallel to the stacking direction T and the length direction L and passing through the central portion in the width direction W of the stacked ceramic capacitor 1, but it may not necessarily be a cross-section passing through the central portion in the width direction W of the stacked ceramic capacitor 1. The LT cross-section only needs to be a cross-section parallel to the stacking direction T and the length direction L of the stacked ceramic capacitor, and the position in the width direction W is not particularly limited.

[0148] In addition, the present invention includes the following combinations.

[0149] <1> A stacked ceramic capacitor, comprising: a stacked body having an inner layer portion including alternately stacked dielectric layers and internal electrodes, a pair of outer layer portions disposed sandwiching the inner layer portion in the stacking direction, a pair of main surfaces facing each other in the stacking direction, a pair of side surfaces facing each other in a width direction orthogonal to the stacking direction, and a pair of end surfaces facing each other in a length direction orthogonal to the stacking direction and the width direction; and external electrodes disposed in pairs on at least any one of the respective side surfaces and the respective end surfaces, wherein when a cross-section parallel to the stacking direction and the length direction is defined as an LT cross-section, in the LT cross-section view, the internal electrode has an arcuate convex portion that depicts a convex arc toward the adjacent dielectric layer side.

[0150] <2> In the stacked ceramic capacitor described in <1>, the dielectric layer has an arcuate concave portion that is recessed toward the inside of the dielectric layer to depict an arc, and an interface is formed in close contact between the arcuate concave portion and the arcuate convex portion of the internal electrode.

[0151] <3> In the stacked ceramic capacitor described in <1> or <2>, the internal electrode has a plurality of conductive particles, and the dielectric layer has a plurality of dielectric particles.

[0152] <4>In the multilayer ceramic capacitor described in <3>, when the number of the conductive particles arranged in the stacking direction in one of the internal electrodes is defined as the number of vertical rows, the number of vertical rows is 3 or more.

[0153] <5>In the multilayer ceramic capacitor described in <3> or <4>, when the number of the conductive particles arranged in the stacking direction in one of the internal electrodes is defined as the number of vertical rows, the surface of the arc-shaped convex portion is formed by arranging the conductive particles in a number equal to or more than the number of vertical rows of the internal electrode on which the arc-shaped convex portion is formed to depict an arc.

[0154] <6>In the multilayer ceramic capacitor described in any one of <3> to <5>, the surface of the arc-shaped convex portion is formed by arranging 5 or more of the conductive particles to depict an arc.

[0155] <7>In the multilayer ceramic capacitor described in any one of <1> to <6>, the dimension in the length direction of the arc-shaped convex portion is larger than the dimension in the stacking direction of the internal electrode on which the arc-shaped convex portion is formed.

[0156] <8>In the multilayer ceramic capacitor described in any one of <3> to <7>, the dimension in the stacking direction of the arc-shaped convex portion is larger than the average particle diameter of the conductive particles in the internal electrode on which the arc-shaped convex portion is formed.

[0157] <9>In the multilayer ceramic capacitor described in any one of <1> to <8>, the radius of curvature of the arc of the arc-shaped convex portion is 1 μm or more and 3 μm or less.

[0158] <10>In the multilayer ceramic capacitor described in any one of <1> to <9>, the radius of curvature of the arc of the arc-shaped convex portion is 1 times or more and 5 times or less the dimension in the stacking direction of the internal electrode on which the arc-shaped convex portion is formed.

[0159] <11>In the multilayer ceramic capacitor described in any one of <1> to <10>, the internal electrode has an expansion portion that expands in two directions in the stacking direction, the expansion portion has the arc-shaped convex portion that protrudes in one direction in the stacking direction and the arc-shaped convex portion that protrudes in the other direction in the stacking direction, and the positions in the length direction of both ends in the length direction of one of the arc-shaped convex portions constituting the expansion portion are aligned with the positions in the length direction of both ends in the length direction of the other arc-shaped convex portion.

[0160] <12>In the multilayer ceramic capacitor described in <11>, a plurality of the expansion portions are continuously formed in the length direction.

[0161] <13>In the multilayer ceramic capacitor described in <12>, the positions in the length direction of the respective ends in the length direction of the swelling portion formed in one of the adjacent internal electrodes and the positions in the length direction of the respective ends in the length direction of the swelling portion formed in the other internal electrode are different from each other.

Claims

1. A multilayer ceramic capacitor comprising: A laminate having an inner layer portion including alternately stacked dielectric layers and internal electrodes, a pair of outer layer portions sandwiching the inner layer portion in a stacking direction, a pair of main surfaces opposing each other in the stacking direction, a pair of side surfaces opposing each other in a width direction orthogonal to the stacking direction, and a pair of end surfaces opposing each other in a length direction orthogonal to the stacking direction and the width direction; and external electrodes arranged in pairs on at least one of the side faces and the end faces, It is characterized in that When a cross section parallel to the stacking direction and the longitudinal direction is defined as an LT cross section, In the LT cross-sectional view, the internal electrode has an arc-shaped convex portion that describes a convex arc toward the adjacent dielectric layer side.

2. The multilayer ceramic capacitor according to claim 1, wherein: The dielectric layer has an arc-shaped recessed portion that is recessed toward the inner side of the dielectric layer to describe an arc, The arc-shaped concave portion and the arc-shaped convex portion of the internal electrode form an interface in close contact with each other.

3. The multilayer ceramic capacitor according to claim 1 or 2, wherein: The internal electrode has a plurality of conductive particles. The dielectric layer has a plurality of dielectric particles.

4. The multilayer ceramic capacitor according to claim 3, wherein: When the number of the conductive particles arranged in the stacking direction in one of the internal electrodes is defined as the number of vertical rows, The number of the vertical rows is 3 or more.

5. The multilayer ceramic capacitor according to claim 3, wherein: When the number of the conductive particles arranged in the stacking direction in one of the internal electrodes is defined as the number of vertical rows, The surface of the arc-shaped protrusion is formed by arranging the conductive particles in a number equal to or greater than the number of the vertical rows of the internal electrodes forming the arc-shaped protrusion so as to describe an arc.

6. The multilayer ceramic capacitor according to claim 3, wherein: The surface of the arc-shaped protrusion is formed by arranging five or more of the conductive particles to form an arc.

7. The multilayer ceramic capacitor according to claim 1 or 2, wherein: The dimension of the arc-shaped protrusion in the longitudinal direction is larger than the dimension of the internal electrode in the stacking direction on which the arc-shaped protrusion is formed.

8. The multilayer ceramic capacitor according to claim 3, wherein: The dimension of the arc-shaped protrusion in the stacking direction is larger than the average particle diameter of the conductive particles in the internal electrode in which the arc-shaped protrusion is formed.

9. The multilayer ceramic capacitor according to claim 1 or 2, wherein: The arc of the arc-shaped convex portion has a curvature radius of 1 μm or more and 3 μm or less.

10. The multilayer ceramic capacitor according to claim 1 or 2, wherein: The radius of curvature of the arc of the arc-shaped convex portion is not less than 1 time and not more than 5 times the dimension in the stacking direction of the internal electrode on which the arc-shaped convex portion is formed.

11. The multilayer ceramic capacitor according to claim 1 or 2, wherein: The internal electrode has a bulging portion bulging in both directions of the stacking direction, The expansion portion includes the arc-shaped convex portion convex in one direction of the stacking direction and the arc-shaped convex portion convex in the other direction of the stacking direction, The positions of both ends in the longitudinal direction of one of the arcuate convex portions constituting the expansion portion and both ends in the longitudinal direction of the other arcuate convex portion are aligned with each other.

12. The multilayer ceramic capacitor according to claim 11, wherein: A plurality of the expansion portions are continuously formed in the longitudinal direction.

13. The multilayer ceramic capacitor according to claim 12, wherein: The positions in the longitudinal direction of each end portion of the expansion portion formed in one of the adjacent internal electrodes and each end portion of the expansion portion formed in the longitudinal direction of the other internal electrode are different from each other.

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