Multilayer ceramic capacitor

Abstract

Provided is a multilayer ceramic capacitor that achieves a balance between an improvement in reliability and an improvement in temperature characteristics. In the multilayer ceramic capacitor, a dielectric layer contains at least Ti, and a region having a width-direction length of 800 nm and a lamination-direction length of 1 nm is divided into 800 cells in a width-direction and lamination-direction center portion of the dielectric layer by a cell having a width-direction length of 1 nm and a lamination-direction length of 1 nm. When a unit having a molar ratio of 5 mol% or more with respect to 100 mol of Ti is a high-concentration unit, the high-concentration unit is present in an amount of 75% or more but less than 100% from among 800 units in the region.

Description

Technical Field

[0001] The present invention relates to a laminated ceramic capacitor. Background Art

[0002] A multilayer ceramic capacitor is known that includes a laminated body in which a plurality of dielectric layers and internal electrode layers are alternately laminated, and an external electrode provided on a surface of the laminated body and electrically connected to the internal electrode layer led out to the surface of the laminated body.

[0003] In recent years, the use of multilayer ceramic capacitors has expanded, but at the same time, the use environment has become increasingly severe, and they are often used in high-temperature environments. In high-temperature environments, when a high electric field is applied, there is a problem that the insulation resistance decreases.

[0004] Patent Document 1 describes a laminated ceramic capacitor including a plurality of crystal grains having barium titanate as a main component and magnesium, manganese, and rare earth elements dissolved as oxides in a dielectric layer. As in the ceramic capacitor described in Patent Document 1, by providing the crystal grains included in the dielectric layer with a core-shell structure including a core portion and a shell portion surrounding the core portion, it is possible to suppress degradation of insulation resistance in a high temperature environment.

[0005] Prior Art Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2008-10530 Summary of the invention

[0008] Problem that the invention aims to solve

[0009] However, even the structure of the laminated ceramic capacitor including core-shell grains in the dielectric layer as described in Patent Document 1 cannot fully suppress the degradation of insulation resistance in a high temperature environment, and there is room for improvement. In addition, there is also a case where the improvement of reliability and the improvement of temperature characteristics are opposite.

[0010] Therefore, an object of the present invention is to provide a laminated ceramic capacitor that achieves a balance between improved reliability and improved temperature characteristics.

[0011] Technical solutions to solve problems

[0012] A multilayer ceramic capacitor comprises a stacked body in which a plurality of dielectric layers and internal electrode layers are alternately stacked, and an external electrode provided on a surface of the stacked body and electrically connected to the internal electrode layer led out to the surface of the stacked body, wherein the dielectric layer contains at least Ti, and in a center portion in a stacking direction and in a width direction perpendicular to the stacking direction of the dielectric layer, a region having a length of 800 nm in the width direction and a length of 1 nm in the stacking direction is divided into 800 cells, with a cell having a size of 1 nm in the width direction and a length of 1 nm in the stacking direction, and when a cell having a molar ratio of 5 mol % or more of rare earth relative to 100 mol of Ti is set as a high-concentration cell, the high-concentration cells account for 75% or more and less than 100% of the 800 cells in the region.

[0013] In addition, a multilayer ceramic capacitor comprises a stacked body in which a plurality of dielectric layers and internal electrode layers are alternately stacked, and an external electrode provided on a surface of the stacked body and electrically connected to the internal electrode layer led out to the surface of the stacked body, wherein the dielectric layer contains at least Ti, and in the center of the stacking direction and the width direction perpendicular to the stacking direction of the dielectric layer, a unit size is a unit having a length of 1 nm in the width direction and a length of 1 nm in the stacking direction, a region having a length of 800 nm in the width direction and a length of 800 nm in the stacking direction is divided into 800 units in the width direction and 800 units in the stacking direction, an arrangement of the units in the width direction is defined as a row, and an arrangement of the units in the stacking direction is defined as a column, a unit having a molar ratio of 5 mol % or more of a rare earth relative to 100 mol of Ti is defined as a high-concentration unit, and a row having 75% or more of the high-concentration units among 800 cells in the same row is defined as a high-concentration row, and the number of high-concentration rows among the 800 rows in the region is 9% or more and 43% or less.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to provide a multilayer ceramic capacitor that achieves a balance between improved reliability and improved temperature characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a perspective view of a multilayer ceramic capacitor of the present invention.

[0017] Figure 2 yes Figure 1 Line II cross-sectional view.

[0018] Figure 3 yes Figure 1 Sectional view along line II-II.

[0019] Figure 4 It is a diagram showing a method of dividing into units.

[0020] Figure 5 It is a diagram showing the distribution of high-concentration cells.

[0021] Figure 6 This is a diagram showing a method of counting the number of high-concentration cells.

[0022] Figure 7 is a diagram showing another distribution of high-concentration cells.

[0023] Figure 8 is a diagram showing another distribution of high-concentration cells.

[0024] Fig. 9 It is a graph showing the characteristics of a multilayer ceramic capacitor. DETAILED DESCRIPTION

[0025] Hereinafter, an example of an embodiment of the present invention will be described with reference to the accompanying drawings. In addition, the same reference numerals are attached to the same or corresponding parts in each drawing.

[0026] <Outline of Multilayer Ceramic Capacitors>

[0027] based on Figure 1 The outline of the appearance of the multilayer ceramic capacitor 1 will be described. Figure 1 1 is a perspective view showing a multilayer ceramic capacitor 1 according to the present embodiment.

[0028] The multilayer ceramic capacitor 1 includes a multilayer body 2 and external electrodes 20. The external electrodes 20 include a first external electrode 20a and a second external electrode 20b.

[0029] <Definition of direction>

[0030] exist Figures 1 to 8 , an L direction, a W direction, and a T direction are shown. The L direction is a length direction L of the multilayer ceramic capacitor 1. The W direction is a width direction W of the multilayer ceramic capacitor 1. The T direction is a stacking direction T of the multilayer ceramic capacitor 1.

[0031] thus, Figure 2 The section shown is called the LT section. Figure 3 The section shown is called the WT section.

[0032] The length direction L, the width direction W, and the stacking direction T do not necessarily need to be orthogonal to each other. The length direction L, the width direction W, and the stacking direction T may be intersecting to each other.

[0033] <Outer Shape of Laminated Body>

[0034] like Figure 1 As shown, the stacked body 2 has a substantially rectangular parallelepiped shape.

[0035] The laminate has two main surfaces M, two end surfaces E, and two side surfaces S. The main surfaces M are surfaces facing each other in the lamination direction T. The end surfaces E are surfaces facing each other in the longitudinal direction L. The side surfaces S are surfaces facing each other in the width direction W.

[0036] The two main surfaces M are referred to as a first main surface M1 and a second main surface M2. The two end surfaces E are referred to as a first end surface E1 and a second end surface E2. The two side surfaces S are referred to as a first side surface S1 and a second side surface S2.

[0037] It is preferable that the ridges and corners of the laminate 2 are rounded. The ridges are the portions where two surfaces of the laminate 2 intersect. The corners are the portions where three surfaces of the laminate 2 intersect.

[0038] <Size of laminated body>

[0039] The size of the laminate 2 is not particularly limited. As an example, the length of the longitudinal direction L of the laminate 2 can be set to be greater than 0.05 mm and less than 1.00 mm. The length of the stacking direction T of the laminate 2 can be set to be greater than 0.10 mm and less than 0.50 mm. The length of the width direction W of the laminate 2 can be set to be greater than 0.10 mm and less than 0.50 mm.

[0040] The length of each part of the laminate 2 can be measured with a micrometer or an optical microscope. In addition, the length in the longitudinal direction L does not necessarily need to be longer than the length in the width direction W.

[0041] <Internal structure of laminate>

[0042] based on Figure 2 , the internal structure of the stacked body 2 is described. Figure 2 yes Figure 1 FIG. 1 is a cross-sectional view of the multilayer ceramic capacitor taken along line II shown in FIG.

[0043] The laminate 2 includes a plurality of dielectric layers 4 and a plurality of internal electrode layers 10. The plurality of dielectric layers 4 and the plurality of internal electrode layers 10 are laminated in a lamination direction T with respect to each other.

[0044] <Inner layer and outer layer>

[0045] The laminate 2 has an inner layer portion IL and an outer layer portion OL in the lamination direction T. The outer layer portion OL includes a first outer layer portion OL1 and a second outer layer portion OL2. The first outer layer portion OL1 and the second outer layer portion OL2 are arranged in the lamination direction T so as to sandwich the inner layer portion IL.

[0046] The inner layer portion IL includes a part of the plurality of dielectric layers 4 and the plurality of internal electrode layers 10. In the inner layer portion IL, the plurality of internal electrode layers 10 are arranged to face each other with the dielectric layer 4 interposed therebetween.

[0047] The inner layer portion IL is a portion that forms electrostatic capacitance and substantially functions as a capacitor. Therefore, the inner layer portion IL is also referred to as an effective portion.

[0048] The first outer layer portion OL1 is arranged on the first main surface M1 side of the laminate 2. The second outer layer portion OL2 is arranged on the second main surface M2 side of the laminate 2.

[0049] Specifically, the first outer layer portion OL1 is disposed between the internal electrode layer 10 closest to the first main surface M1 and the second outer layer portion OL2 is disposed between the internal electrode layer 10 closest to the second main surface M2 and the second main surface M2.

[0050] The first outer layer portion OL1 and the second outer layer portion OL2 do not include the internal electrode layer 10. The first outer layer portion OL1 and the second outer layer portion OL2 include the remaining dielectric layers 4 among the plurality of dielectric layers 4 except the dielectric layers 4 used for the inner layer portion IL.

[0051] The first outer layer portion OL1 and the second outer layer portion OL2 function as protective layers for the inner layer portion IL.

[0052] <Dielectric Layer>

[0053] The dielectric layer 4 includes an outer dielectric layer 5 and an inner dielectric layer 6 .

[0054] <Outer Dielectric Layer>

[0055] The outer dielectric layer 5 is a dielectric layer 4 constituting the first outer layer portion OL1 and the second outer layer portion OL2 among the dielectric layers 4. The outer dielectric layer 5 is arranged between the first main surface M1 and the internal electrode layer 10 closest to the first main surface M1, and between the second main surface M2 and the internal electrode layer 10 closest to the second main surface M2.

[0056] <Inner Dielectric Layer>

[0057] The inner dielectric layer 6 is a dielectric layer 4 that is located between the internal electrode layers 10 and constitutes the inner layer portion IL together with the internal electrode layers 10 .

[0058] The inner dielectric layer 6 is arranged between a first internal electrode layer 10 a and a second internal electrode layer 10 b described below.

[0059] <Number of Dielectric Layers>

[0060] The number of dielectric layers 4 stacked in the stacked body 2 can be, for example, 10 or more and 2000 or less.

[0061] <Thickness of Dielectric Layer>

[0062] The thickness of the outer dielectric layer 5 among the dielectric layers 4 can be set to, for example, 10 μm or more and 100 μm or less. The thickness of the inner dielectric layer 6 can be set to, for example, 0.8 μm or more and 3.0 μm or less.

[0063] <Material for Dielectric Layer>

[0064] The material of the dielectric layer 4 can be made of, for example, BaTiO 3 , CaTiO 3 , SrTiO 3、 Dielectric ceramics such as CaZrO3 or TiO2.

[0065] The material of the dielectric layer 4 may be a material obtained by adding a Mn compound, an Fe compound, a Cr compound, a Co compound, a Ni compound, etc., in an amount smaller than the main component, to the above-mentioned dielectric ceramic.

[0066] <Internal Electrode Layer>

[0067] The internal electrode layer 10 includes a first internal electrode layer 10a and a second internal electrode layer 10b. The first internal electrode layer 10a is an internal electrode layer 10 connected to the first external electrode 20a. The second internal electrode layer 10b is an internal electrode layer 10 connected to the second external electrode 20b.

[0068] The first internal electrode layer 10a extends from the first end surface E1 toward the second end surface E2. The second internal electrode layer 10b extends from the second end surface E2 toward the first end surface E1.

[0069] <Opposing portion and lead portion>

[0070] The first internal electrode layer 10 a and the second internal electrode layer 10 b each have a counter electrode portion 11 and a lead electrode portion 12 .

[0071] The counter electrode portion 11 is a portion of the internal electrode layer 10 where the first internal electrode layer 10 a and the second internal electrode layer 10 b face each other in the stacking direction T. The lead electrode portion 12 is a portion of the internal electrode layer 10 that is led out from the counter electrode portion 11 to the end surface E1 or the end surface E2 of the stacked body 2 .

[0072] The counter electrode portion 11 of the first internal electrode layer 10a is referred to as a first counter electrode portion 11a, and the lead electrode portion 12 of the first internal electrode layer 10a is referred to as a first lead electrode portion 12a. The first lead electrode portion 12a is a portion extending from the first counter electrode portion 11a to the first end surface E1 of the laminate 2.

[0073] Similarly, the counter electrode portion 11 of the second internal electrode layer 10b is referred to as the second counter electrode portion 11b, and the lead electrode portion 12 of the second internal electrode layer 10b is referred to as the second lead electrode portion 12b. The second lead electrode portion 12b is a portion extending from the second counter electrode portion 11b to the second end surface E2 of the laminate 2.

[0074] <Number of Internal Electrode Layers>

[0075] The number of the internal electrode layers 10 can be, for example, not less than 10 and not more than 1000. The number of the internal electrode layers 10 includes the number of the first internal electrode layers 10a and the second internal electrode layers 10b.

[0076] <Thickness of Internal Electrode Layer>

[0077] The thickness of the internal electrode layer 10 can be set to, for example, 0.3 μm or more and 0.4 μm or less.

[0078] <Material of Internal Electrode Layer>

[0079] The material of the internal electrode layer 10 can be, for example, metals such as Ni, Cu, Ag, Pd, and Au, alloys of Ni and Cu, alloys of Ag and Pd, etc. In addition, the material of the internal electrode layer 10 may include dielectric particles of the same composition as the ceramic included in the dielectric layer 4 .

[0080] Sn may be disposed at the interface between the internal electrode layer 10 and the dielectric layer 4. The Sn may be in a layered form or may be dispersed.

[0081] Sn may be dissolved in the internal electrode layer 10 side or in the dielectric particles in the dielectric layer 4 side.

[0082] <Electrode Opposing Section>

[0083] The division of the laminate 2 in the longitudinal direction L will be described.

[0084] The laminated body 2 has an electrode facing portion LF and an end gap portion EG in the longitudinal direction L. The end gap portion EG includes a first end gap portion EG1 and a second end gap portion EG2.

[0085] The electrode facing portion LF is a portion where the first internal electrode layer 10 a and the second internal electrode layer 10 b face each other in the stacking direction T. That is, the electrode facing portion LF is a portion where the first counter electrode portion 11 a and the second counter electrode portion 11 b face each other in the stacking direction T.

[0086] The electrode facing portion LF is located at the center portion in the longitudinal direction L of the stacked body 2 .

[0087] The electrode facing portion LF is a portion that forms electrostatic capacitance and substantially functions as a capacitor. Therefore, the electrode facing portion LF is also called an effective portion.

[0088] <End Gap>

[0089] The end gap portion EG is a portion where the first internal electrode layer 10 a and the second internal electrode layer 10 b do not face each other in the stacking direction T.

[0090] Specifically, a portion where the first internal electrode layer 10a is arranged but the second internal electrode layer 10b is not arranged in the stacking direction T is a first end gap EG1. Similarly, a portion where the second internal electrode layer 10b is arranged but the first internal electrode layer 10a is not arranged is a second end gap EG2.

[0091] The first end gap EG1 corresponds to a portion where the first extraction electrode portion 12 a is arranged, and the second end gap EG2 corresponds to a portion where the second extraction electrode portion 12 b is arranged.

[0092] The first end gap EG1 functions as an extraction electrode of the first internal electrode layer 10a to the first end surface E1, and the second end gap EG2 functions as an extraction electrode of the second internal electrode layer 10b to the second end surface E2.

[0093] The end gap portion EG is a division in the length direction L, and therefore is also referred to as an L gap.

[0094] The length of the end gap portion EG in the longitudinal direction L can be set to, for example, 5 μm or more and 30 μm or less.

[0095] <External Electrode>

[0096] The external electrodes include a first external electrode 20 a and a second external electrode 20 b .

[0097] <First External Electrode>

[0098] The first external electrode 20a is an external electrode disposed on the first end surface E1 of the stacked body 2. The first external electrode 20a is electrically connected to the first internal electrode layer 10a.

[0099] <Second External Electrode>

[0100] The second external electrode 20b is an external electrode disposed on the second end surface E2 of the stacked body 2. The second external electrode 20b is electrically connected to the second internal electrode layer 10b.

[0101] <External electrodes on each surface>

[0102] The external electrode 20 extends from the end surface E to a portion of the two main surfaces M and a portion of the two side surfaces S.

[0103] The portion of the external electrode 20 disposed on the end surface E is referred to as the end surface external electrode 25 . The portion of the external electrode 20 disposed on a part of the main surface M is referred to as the main surface external electrode 26 . The portion of the external electrode 20 disposed on a part of the side surface S is referred to as the side surface external electrode 27 .

[0104] Specifically, a portion of the first external electrode 20a disposed on the first end surface E1 is set as a first end surface external electrode 25a. A portion of the first external electrode 20a disposed on a portion of the first principal surface M1 or a portion of the second principal surface M2 is set as a first principal surface external electrode 26a. A portion of the first external electrode 20a disposed on a portion of the first side surface S1 or a portion of the second side surface S2 is set as a first side surface external electrode 27a.

[0105] In addition, as with the first external electrode 20, the portion of the second external electrode 20b disposed on the second end surface E2 is set as the second end surface external electrode 25b. The portion of the second external electrode 20b disposed on a portion of the first main surface M1 or a portion of the second main surface M2 is set as the second main surface external electrode 26b. The portion of the second external electrode 20b disposed on a portion of the first side surface S1 or a portion of the second side surface S2 is set as the second side surface external electrode 27b.

[0106] <Layer Structure of External Electrode>

[0107] based on Figure 2 The layer structure of the external electrode 20 will be described.

[0108] The external electrode 20 includes three layers: a base electrode layer 21 , an inner plating layer 23 , and an outer plating layer 24 . These layers are arranged in the order of the base electrode layer 21 , the inner plating layer 23 , and the outer plating layer 24 from the end surface E of the laminate 2 .

[0109] Specifically, the first external electrode 20a includes a first base electrode layer 21a, a first inner plating layer 23a, and a first outer plating layer 24a. Similarly, the second external electrode 20b includes a second base electrode layer 21b, a second inner plating layer 23b, and a second outer plating layer 24b.

[0110] In the description of the external electrode 20 , a direction away from the end surface E of the stacked body 2 may be referred to as upward.

[0111] <Base Electrode Layer>

[0112] The first foundation electrode layer 21a is disposed on and covers the first end surface E1 of the laminate 2. The first foundation electrode layer 21a may extend from the first end surface E1 to a portion of the first principal surface M1, a portion of the second principal surface M2, a portion of the first side surface S1, and a portion of the second side surface S2.

[0113] Similarly, the second foundation electrode layer 21b is arranged on the second end face E2 of the stacked body 2 to cover the second end face E2. The second foundation electrode layer 21b may extend from the second end face E2 to a portion of the second main face M1, a portion of the second main face M2, a portion of the first side face S1, and a portion of the second side face S2.

[0114] <Fired layer>

[0115] The base electrode layer 21 can be a fired layer containing metal and glass.

[0116] The fired layer is a layer formed by applying a conductive paste containing metal and glass to a laminate by a dipping method and firing the paste. The fired layer may be a plurality of layers.

[0117] The metal contained in the sintered layer includes Cu as a main component. In addition, as the metal, for example, at least one selected from metals such as Ni, Ag, Pd or Au, or alloys such as Ag-Pd alloys may be included as a main component, or a component other than the main component may be included.

[0118] Examples of the glass contained in the fired layer include a glass component containing at least one selected from B, Si, Ba, Mg, Al, Li, etc. As a specific example, borosilicate glass can be used.

[0119] Furthermore, the base electrode layer 21 may be a conductive resin layer containing conductive particles and a thermosetting resin. The conductive resin layer may be formed on the above-mentioned fired layer, or may be formed directly on the laminate without forming a fired layer.

[0120] The conductive resin layer is a layer formed by applying a conductive paste containing conductive particles and a thermosetting resin to a laminate by a coating method and then firing the paste.

[0121] The thickness of each of the base electrode layers 21 as the fired layer or the conductive resin layer is not particularly limited, and may be 1 μm or more and 10 μm or less.

[0122] Alternatively, the base electrode layer 21 may be a thin film layer having a thickness of 1 μm or less formed by a thin film forming method such as sputtering or vapor deposition and in which metal particles are deposited.

[0123] <Inner plating>

[0124] The inner plating layer 23 is disposed on the base electrode layer 21 and covers at least a portion of the base electrode layer 21. The inner plating layer 23 includes at least one selected from metals such as Cu, Ni, Ag, Pd, and Au, and alloys such as Ag-Pd alloy.

[0125] <Surface coating>

[0126] The outer plating layer 24 is disposed on the inner plating layer 23 and covers at least a portion of the inner plating layer 23. The outer plating layer 24 includes a metal such as Sn.

[0127] The inner plating layer 23 is preferably a Ni plating layer, and the outer plating layer 24 is preferably a Sn plating layer.

[0128] The Ni plating layer can prevent the base electrode layer from being corroded by the solder when the ceramic electronic components are mounted. The Sn plating layer can improve the wettability of the solder when the ceramic electronic components are mounted, making the mounting easier. By setting the outer surface plating layer 24 as the Sn plating layer, the wettability of the solder to the external electrode 20 can be improved.

[0129] <Other structures of external electrodes>

[0130] The external electrode 20 can be a plated layer that is directly provided on the laminate 2 and directly connected to the internal electrode layer 10. In addition, a catalyst may be provided on the laminate 2 as a pre-treatment of the plating.

[0131] The plating layer preferably includes a first plating layer and a second plating layer provided on the first plating layer.

[0132] The first plating layer and the second plating layer are preferably plating including one metal selected from the group consisting of Cu, Ni, Sn, Pb, Au, Ag, Pd, Bi, and Zn, or an alloy containing the metal, for example.

[0133] For example, when Ni is used as the internal electrode layer 10 , it is preferable to use Cu having good bonding properties with Ni as the first plating layer.

[0134] In addition, as the second plating layer, Sn or Au having good solder wettability is preferably used. On the other hand, as the first plating layer, Ni having solder barrier properties is preferably used.

[0135] The second plating layer is formed as needed. Therefore, the external electrode 20 may be composed of only the first plating layer.

[0136] In addition, the second plating layer may be provided as the outermost layer of the plating layer, or another plating layer may be provided on the second plating layer.

[0137] Furthermore, the metal ratio per unit volume of the plating layer is preferably 99 volume % or more.

[0138] Furthermore, the plating layer may be a plating layer in which grains have grown along the stacking direction T, and may also be in a columnar shape.

[0139] <Internal structure of laminate (WT cross section)>

[0140] based on Figure 3 The internal structure of the stacked body 2 , particularly the internal structure viewed from the second end surface E2 , will be described. Figure 3 yes Figure 1 FIG. 1 is a cross-sectional view of the multilayer ceramic capacitor taken along line II-II shown in FIG.

[0141] The laminate 2 has an electrode facing portion WF where the internal electrode layers 10 face each other and side gap portions SG in the width direction W. The side gap portions SG include first side gap portions SG1 and second side gap portions SG2. The first side gap portions SG1 and the second side gap portions SG2 are arranged to sandwich the electrode facing portion WF.

[0142] The first side gap SG1 is located between the electrode opposing portion WF and the first side surface S1 , and the second side gap SG2 is located between the electrode opposing portion WF and the second side surface S2 .

[0143] Specifically, the first side gap SG1 is located between the end of the internal electrode layer 10 on the first side face S1 and the first side face S1 , and the second side gap SG2 is located between the end of the internal electrode layer 10 on the second side face S2 and the second side face S2 .

[0144] The first side gap portion SG1 and the second side gap portion SG2 do not include the internal electrode layer 10 , and include only the dielectric layer 4 .

[0145] The first side gap portion SG1 and the second side gap portion SG2 function as a protective layer for the internal electrode layer 10 .

[0146] The side gap portion SG is a partition in the width direction W, and therefore is also called a W gap.

[0147] The length of the side gap portion SG in the width direction W can be set to, for example, 1 / 10 of the length of the stacked body 2 in the width direction W or to 5 μm or more and 30 μm or less.

[0148] <Size of Multilayer Ceramic Capacitors>

[0149] The length L of the entire multilayer ceramic capacitor 1 including the laminate 2 and the external electrode 20 can be set to, for example, 0.2 mm or more and 2.0 mm or less. The length T of the entire multilayer ceramic capacitor 1 in the stacking direction can be set to, for example, 0.1 mm or more and 1.2 mm or less. The length W of the entire multilayer ceramic capacitor 1 in the width direction can be set to, for example, 0.1 mm or more and 1.2 mm or less.

[0150] In addition, in the present embodiment, the multilayer ceramic capacitor 1 is a two-terminal capacitor. The multilayer ceramic capacitor 1 is not limited to a two-terminal capacitor, and can be a multi-terminal capacitor of three or more terminals.

[0151] <Distribution of rare earth elements>

[0152] The distribution of rare earth elements in dielectric layer 4 will be described.

[0153] The multilayer ceramic capacitor 1 of the present embodiment is characterized by the distribution of rare earth elements in the dielectric layer 4 .

[0154] For example, in the dielectric layer 4 containing BaTiO 3 , when a high temperature / high electric field load is applied to the ceramic grain boundary, oxygen vacancies migrate and the insulation resistance deteriorates.

[0155] Here, by dissolving rare earths such as Re in BaTiO3, the movement of oxygen vacancies is suppressed. Furthermore, the more regions in which rare earths are dissolved in the electric field direction, the more the movement of oxygen vacancies is suppressed, and the higher the reliability becomes.

[0156] In the multilayer ceramic capacitor 1 of this embodiment, rare earth is uniformly dissolved in the electrolysis direction at a high concentration. Specifically, by forming a region uniformly dissolved in the rare earth in the electric field direction, that is, the stacking direction T, the movement of oxygen vacancies is inhibited, thereby improving reliability.

[0157] Below, refer to the attached Figure 1 While explaining.

[0158] Figure 4 WT is a cross-sectional view of the inner dielectric layer 6 .

[0159] Figure 4 The region shown is a region having a length of 800 nm in the width direction W and a length of 800 nm in the stacking direction T in the central portion of the inner dielectric layer 6 in the width direction W and the central portion of the stacking direction T. Hereinafter, a given region in the central portion of the width direction W and the central portion of the stacking direction T of the inner dielectric layer 6 is sometimes referred to as an evaluation region.

[0160] Figure 4The lattice shown is a lattice having a length of 1 nm in the width direction W and a length of 1 nm in the stacking direction T. One of these lattices corresponds to one unit.

[0161] Furthermore, the arrangement of cells extending in the width direction W is referred to as a row, and the arrangement of cells extending in the stacking direction T is referred to as a column.

[0162] Figure 4 The area shown is divided into 800 rows by 800 columns, for a total of 640,000 cells.

[0163] <High Concentration Unit and Low Concentration Unit>

[0164] Figure 4 The unit H in represents a high concentration unit, Figure 4 The unit L in represents a low concentration unit.

[0165] Here, the high concentration unit refers to a unit in which the molar ratio of the rare earth to 100 moles of Ti in the unit is 5 mol% or more, while the low concentration unit refers to a unit in which the molar ratio of the rare earth to 100 moles of Ti in the unit is less than 5 mol%.

[0166] In addition, as a rare earth element, for example, it can be set to at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y.

[0167] In the multilayer ceramic capacitor 1 of the present embodiment, 600 or more and less than 800 high-concentration cells exist among 800 cells continuous in the width direction W. That is, among the cells in a row, 75% or more and less than 100% are high-concentration cells.

[0168] Thereby, the reliability in the electrolysis direction, in other words, in the stacking direction T, is improved.

[0169] On the other hand, if the ratio of the high-concentration cells H is too high, the temperature characteristics deteriorate. In the multilayer ceramic capacitor 1 of the present embodiment, the low-concentration cells L and the high-concentration cells H coexist.

[0170] Therefore, it is possible to provide a laminated ceramic capacitor that achieves a balance between improved reliability and improved temperature characteristics.

[0171] The dielectric layer 4 includes a plurality of dielectric particles. The dielectric particles are barium titanate-based ceramics such as perovskite compounds containing Ba and Ti, and are ceramic layers containing perovskite compounds containing Ba and Ti and rare earths. Here, in a high-concentration unit containing a given amount or more of rare earths, the rare earths are easily dissolved in barium titanate, etc. In the portion where the rare earths are dissolved, the movement of oxygen vacancies is easily suppressed.

[0172] Here, if a given ratio or more of high-concentration cells exist in the width direction W or in other words, in the row direction orthogonal to the electrolysis direction, the movement of oxygen vacancies can be effectively suppressed. As a result, the reliability of the multilayer ceramic capacitor 1 can be improved.

[0173] based on Figure 5 as well as Figure 6 Let's explain it in detail.

[0174] Figure 5 This is a diagram showing the distribution of the high-concentration region H in 800 nm×800 nm in the aforementioned evaluation region.

[0175] Figure 5 501 shows the distribution of the molar ratio of rare earth elements in the cell based on TEM (Transmission Electron Microscope)-EDX (Energy Dispersive X-ray Spectroscopy).

[0176] Figure 5 502 is a diagram showing the distribution of the molar ratio of the rare earth of each unit by binarization. In the binarization, the unit having a molar ratio of the rare earth of 5 mol% or more relative to the molar ratio of Ti100 is set as a high-concentration unit H, and the unit having a molar ratio of the rare earth of less than 5 mol% relative to the molar ratio of Ti100 is set as a low-concentration unit L.

[0177] Figure 5 503 is a diagram showing the proportion of the high-concentration cells H in each row.

[0178] like Figure 5 As shown, by binarizing the analysis results by TEM-EDX, the ratio of the high-concentration cells H in each row can be obtained.

[0179] based on Figure 6 , a method for obtaining the ratio of the high-concentration cells H in each row will be described in detail.

[0180] Figure 6 The 601 is with Figure 5 502 similarly shows a graph showing the distribution of the molar ratio of the rare earth element in each unit after being binarized.

[0181] Figure 6 The 602 is Figure 6 The four sides of 601 are surrounded by R after enlargement.

[0182] As mentioned above, the evaluation area was divided into 1 nm × 1 nm units. Then, the analysis based on TEM-EDX and the binarization of the results were performed for each unit. Figure 6 As shown in 602, the binarized result is output as a mosaic type with a unit of 1 nm.

[0183] Then, for each row, by summing up the number of high-concentration cells H, Figure 5 The ratio of high-concentration cells H in each row as shown in 503.

[0184] In addition, similarly, how the proportion of the high-concentration cells H is distributed in the stacking direction T can be determined.

[0185] exist Figure 5 In the example shown, there is a row in which the ratio of the high-concentration cells H is 75% or more and less than 100% in the row direction.

[0186] Figure 7 as well as Figure 8 It is the corresponding one among other multilayer ceramic capacitors Figure 5 .

[0187] Figure 7 The ratio of high concentration unit H is shown Figure 5 The multilayer ceramic capacitor 1 shown is a high example. In addition, Figure 8 The ratio of high concentration unit H is shown Figure 5 The multilayer ceramic capacitor 1 shown is an example of a low-profile.

[0188] exist Figure 7 In the stacked ceramic capacitors shown in Figure 7 As shown in 702, Figure 5 Compared with 502, the proportion of high-concentration unit H becomes higher. Figure 7 As shown in 703, in all rows in the stacking direction T, the proportion of the high-concentration cells H is greater than 75%.

[0189] On the other hand, Figure 8 In the stacked ceramic capacitors shown in Figure 8 As shown in 802, Figure 5 Compared with 502, the proportion of high-concentration unit H becomes lower. Figure 8 As shown in 803, there is no row in which the proportion of high-concentration units H is greater than 75%.

[0190] <Distribution in stacking direction>

[0191] Next, the distribution of the high-concentration cells H in the column direction, that is, in the stacking direction T will be described.

[0192] Here, a row in which 75% or more of the 800 cells in the same row have high-concentration cells is defined as a high-concentration row.

[0193] The high-density lines preferably account for 9% or more and 43% or less of the total number of lines included in the evaluation region. When the total number of lines is 800, the high-density lines preferably account for 72 or more and 344 or less.

[0194] The presence of high-concentration cells H at a predetermined ratio or more can improve the reliability of the multilayer ceramic capacitor 1 .

[0195] However, if the ratio of the high-concentration unit H is too high, the temperature characteristics will deteriorate.

[0196] Therefore, by setting the ratio of high-density lines to 9% or more and 43% or less of the total number of 800 lines included in the evaluation region, it is possible to improve reliability while suppressing a decrease in temperature characteristics.

[0197] In the previously shown Figure 5 In the stacked ceramic capacitors, such as Figure 5 As shown in 503, 281 rows out of 800 rows are high-density rows. The proportion of high-density rows is 35%.

[0198] Therefore, in Figure 5 In the multilayer ceramic capacitor shown, it is possible to improve reliability while suppressing a decrease in temperature characteristics.

[0199] On the other hand, Figure 7 In the stacked ceramic capacitors shown in Figure 7 As shown in 703, all 800 rows become high-density rows. Figure 7 The temperature characteristics of the multilayer ceramic capacitors shown are not as good as those of Figure 5 of stacked ceramic capacitors.

[0200] <Low concentration unit>

[0201] Next, the ratio of the low-concentration unit L will be described.

[0202] As described above, the low-concentration unit L is a unit having a rare earth molar ratio of less than 5 mol% relative to Ti 100 mol. The number of the low-concentration units L is preferably 71% or less relative to the total number of units in the evaluation region.

[0203] If the ratio of the low-concentration cells L exceeds a given range, reliability cannot be guaranteed. If the area occupied by the low-concentration cells L increases, an escape path for electrons may be formed in the electric field direction. Therefore, reliability cannot be guaranteed.

[0204] <Features>

[0205] Next, based on Fig. 9 The characteristics of the embodiment of the present invention and the comparative example are shown. Fig. 9 It is a table showing characteristics and the like of Examples and Comparative Examples of the present invention.

[0206] in addition, Fig. 9 The ratio of high-concentration regions in one row is the ratio of high-concentration cells in the cells in one row. For example, if 200 cells out of 800 cells in one row are high-concentration cells, the ratio of high-concentration regions in one row is 25%.

[0207] MTTF refers to the mean time to failure (mean time to failure).

[0208] The high-density area ratio refers to the ratio of high-density rows among 800 rows, when a row in which 75% or more of the 800 cells belonging to the same row are high-density rows. For example, when there are 200 high-density rows among 800 rows, the high-density area ratio is 25%.

[0209] The low-concentration area ratio refers to the ratio of low-concentration cells to all cells in the evaluation area. For example, if there are 320,000 low-concentration cells among 640,000 cells of 800 rows×800 columns, the low-concentration area ratio is 50%.

[0210] <mttf>

[0211] like Fig. 9 As shown, in Examples 1 to 6, where the proportion of the high-concentration region in one row is 75% or more and less than 100%, excellent MTTF is shown compared to Comparative Examples 2 and 3, where the proportion of the high-concentration region in one row is less than 75%. In addition, Comparative Example 1, where the proportion of the high-concentration region in one row is 100%, has a good MTTF, but poor temperature characteristics of the relative dielectric constant.

[0212] Likewise, in Examples 1 to 6 in which the high-concentration region ratio is 9% or more and 43% or less, the MTTF is good as described above.

[0213] In addition, the temperature characteristics were good in Examples 1 to 6, in which the low concentration region ratio was 71% or less. In addition, the other characteristics of Comparative Example 1, in which the low concentration region ratio was 0%, were out of the preferred range.

[0214] <Measurement method>

[0215] The sample for TEM-EDX described above can be prepared by cross-polishing the laminate 2 in the central portion in the longitudinal direction L to expose the surface in the width direction W and the stacking direction T. Then, the central portion of the cross section is photographed at 800 nm×800 nm.

[0216] <Measurement method of dielectric constant>

[0217] Next, a method for measuring the dielectric constant will be described.

[0218] A voltage of 1 kHz and 0.8 kV / mm was applied to measure the electrostatic capacitance, and then the dielectric constant was calculated according to the following formula.

[0219]

[0220] In addition, Cap is the dielectric constant, εr is the relative dielectric constant of the sample, ε0 is the dielectric constant of a vacuum, S is the area of ​​the electrode, and d is the thickness of the dielectric layer.

[0221] <Method for Manufacturing Multilayer Ceramic Capacitor>

[0222] As a general flow of the manufacturing process, the multilayer ceramic capacitor 1 of the present embodiment can be manufactured by the same method as the conventional multilayer ceramic capacitor 1 .

[0223] Furthermore, in order to realize a desired distribution of rare earth elements in dielectric layer 4 , for example, the following method can be used.

[0224] That is, when manufacturing the stacked block, the distribution of rare earths in the plane of the stacked dielectric sheets is adjusted. Also, when stacking the dielectric sheets, the distribution of rare earths in the stacked dielectric sheets is adjusted so that the distribution of rare earths in the stacking direction becomes a desired distribution.

[0225] Thereby, the rare earth elements can be distributed in the width direction W, the length direction L, and the stacking direction T in a desired form.

[0226] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Various changes and deformation|transformation are possible.

[0227] Description of Reference Numerals

[0228] 1 Multilayer Ceramic Capacitors

[0229] 2 Laminated body

[0230] 4 Dielectric layer

[0231] 5 Outer dielectric layer

[0232] 6 Inner dielectric layer

[0233] 10 Internal electrode layer

[0234] 11 Counter electrode part

[0235] 12 Lead-out electrode

[0236] 20 External electrodes

[0237] 21. Base electrode layer

[0238] 23 Inner plating

[0239] 24 Surface coating

[0240] 25 End surface external electrode

[0241] 26 Main surface external electrode

[0242] 27 Side external electrode

[0243] IL Inner layer

[0244] OL Outer layer

[0245] LF Electrode Opposition

[0246] EG End gap

[0247] WF Electrode facing part

[0248] SG Side clearance

[0249] M Main surface

[0250] E end face

[0251] S side

[0252] T stacking direction

[0253] L Length direction

[0254] W Width direction.< / mttf>

Claims

1. A laminated ceramic capacitor, characterized in that: have: a laminated body in which a plurality of dielectric layers and internal electrode layers are alternately laminated; and an external electrode disposed on the surface of the stack and electrically connected to the internal electrode layer led out to the surface of the stack, The dielectric layer contains at least Ti, In the center of the dielectric layer in the stacking direction and in the width direction perpendicular to the stacking direction, the region with a width length of 800 nm and a stacking direction length of 1 nm is divided into 800 units, with one unit having a length of 1 nm in the width direction and a length of 1 nm in the stacking direction. When a cell having a rare earth molar ratio of 5 mol % or more to 100 mol of Ti is defined as a high-concentration cell, the high-concentration cells account for 75% or more and less than 100% of the 800 cells in the region.

2. A laminated ceramic capacitor, characterized in that: have: a laminated body in which a plurality of dielectric layers and internal electrode layers are alternately laminated; and an external electrode disposed on the surface of the stack and electrically connected to the internal electrode layer led out to the surface of the stack, The dielectric layer contains at least Ti, In the center of the dielectric layer in the stacking direction and in the width direction orthogonal to the stacking direction, a unit size is a unit with a length of 1 nm in the width direction and a length of 1 nm in the stacking direction, and a region with a length of 800 nm in the width direction and a length of 800 nm in the stacking direction is divided into 800 units in the width direction and 800 units in the stacking direction, The arrangement of cells in the width direction is called rows, and the arrangement of cells in the stacking direction is called columns. The unit in which the molar ratio of the rare earth to 100 moles of Ti is 5 mol% or more is defined as a high-concentration unit. When a row in which 75% or more of the 800 cells in the same row have high-density cells is defined as a high-density row, Among the 800 rows in the region, the high-concentration rows account for 9% or more and 43% or less.

3. The multilayer ceramic capacitor according to claim 2, wherein: When a unit in which the molar ratio of the rare earth to 100 moles of Ti is less than 5 mol % is used as a low-concentration unit, The number of the low-concentration cells is less than 71% of the total number of cells in the region.

4. The multilayer ceramic capacitor according to any one of claims 1 to 3, wherein The dielectric layer has a thickness of 0.8 μm or more and 3.0 μm or less.

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