Multilayer ceramic capacitor

Abstract

Provided is a multilayer ceramic capacitor in which a decrease in high-temperature reliability is suppressed. In a laminated ceramic capacitor (1), a laminated body (2) has an effective layer width direction end portion (201) and an effective layer center portion (202), the laminated body (2) further has a rare earth segregation region (81) in which a rare earth element is segregated, and the amount of segregation of the rare earth element in the rare earth segregation region (81) existing in the effective layer width direction end portion (201) is greater than the amount of segregation of the rare earth element in the effective layer width direction end portion (201). The amount of segregation of a rare earth element in a rare earth segregation region (81) present in the effective layer center portion (202) is in the effective layer center portion (gt). The effective layer has a relationship between ends in the width direction.

Description

Technical Field

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

[0002] For example, the multilayer ceramic capacitor described in Patent Document 1 includes a capacitor body comprising a ceramic sintered body composed of a dielectric such as barium titanate. Internal electrode layers composed of precious metals such as silver or a silver-palladium alloy, or base metals such as nickel, are arranged within the capacitor body, sandwiching a ceramic layer serving as the dielectric layer. The internal electrode layers are alternately extended to one end face and the other end face of the capacitor body. The alternating internal electrode layers are electrically connected to external electrodes at different potentials.

[0003] The multilayer capacitor described in Patent Document 1 has internal electrode layers made of a metal material, and external electrodes made of multiple metal components, including the same metal as or alloyable with the internal electrode layers, and a glass component. The external electrodes are bonded to the wiring substrate via a conductive resin adhesive. The area of ​​the metal component relative to the cross-sectional area of ​​the external electrode ranges from 60% to 95%. As a result, the multilayer capacitor described in Patent Document 1 can be mounted on the wiring substrate at low cost and with high reliability without the use of solder.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-237137

[0007] Furthermore, conventional multilayer ceramic capacitors as described above have a problem in that their high-temperature reliability may be reduced. In particular, the reduction in high-temperature reliability may occur starting at the widthwise ends of the internal electrode layers. Summary of the Invention

[0008] Problems to be solved by the invention

[0009] Therefore, an object of the present invention is to provide a multilayer ceramic capacitor in which a decrease in high-temperature reliability is suppressed.

[0010] Technical solutions to solve problems

[0011] The multilayer ceramic capacitor of the present invention comprises: a laminated body including a plurality of laminated dielectric layers and a plurality of laminated internal electrode layers, the laminated body including a first main surface and a second main surface facing each other in a height direction, a first side surface and a second side surface facing each other in a width direction perpendicular to the height direction, and a first end surface and a second end surface facing each other in a length direction perpendicular to the height direction and the width direction, the laminated body including an effective layer portion and an outer layer portion, the effective layer portion being formed by alternately laminating the dielectric layers and the internal electrode layers, the outer layer portion being arranged so as to sandwich the effective layer portion from the first main surface side and the second main surface side; a first external electrode arranged on the first end surface; and a second external electrode arranged on the second end surface. , wherein the stacked body comprises: an end portion in the width direction of the effective layer, which is arranged at an end portion in the width direction of the effective layer portion; and a central portion of the effective layer, which is arranged at the central portion of the effective layer portion, and the stacked body further comprises a rare earth segregation region where rare earth elements are segregated, and in a cross section parallel to the width direction and the height direction, relative to the segregation amount of the rare earth elements in the rare earth segregation region in the end portion in the width direction of the effective layer, the segregation amount of the rare earth elements in the rare earth segregation region in the central portion of the effective layer is in the relationship of the central portion of the effective layer > the end portion in the width direction of the effective layer, and the dielectric material of the dielectric layer contains a material containing at least one of calcium, zirconium, and strontium and having a perovskite structure.

[0012] Effects of the Invention

[0013] According to the present invention, a multilayer ceramic capacitor can be provided in which a decrease in high-temperature reliability is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a perspective view of the appearance of a multilayer ceramic capacitor according to one embodiment of the present disclosure.

[0015] Figure 2 yes Figure 1 101-101 cross-sectional view.

[0016] Figure 3 yes Figure 2 102-102 cross-sectional view.

[0017] Figure 4 yes Figure 2 103-103 cross-sectional view.

[0018] Figure 5 yes Figure 2 104-104 cross-sectional view.

[0019] Figure 6A yes Figure 2 106-106 cross-sectional view.

[0020] Figure 6B yes Figure 2 105-105 cross-sectional view.

[0021] Figure 7A This is an electron microscope image of the end evaluation area.

[0022] Figure 7B This is an electron microscope image of the central evaluation area.

[0023] Figure 8A It is an FE-WDX image of the edge evaluation area, and is a diagram showing the segregation of rare earth elements.

[0024] Figure 8B It is an FE-WDX image of the central evaluation area, and is a diagram showing the segregation of rare earth elements.

[0025] Figure 9A It is an FE-WDX image of the edge evaluation area, and is a diagram showing the segregation of aluminum.

[0026] Figure 9B It is an FE-WDX image of the central evaluation area, and is a diagram showing the segregation of aluminum.

[0027] Figure 10 This is a table showing the evaluation results of Examples and Comparative Examples.

[0028] Description of Reference Numerals

[0029] 1: Multilayer ceramic capacitor;

[0030] 2: laminate;

[0031] 3: The first main surface;

[0032] 4: The second main side;

[0033] 5: 1st side;

[0034] 6: 2nd side;

[0035] 7: 1st end face;

[0036] 8: Second end face;

[0037] 10: inner layer;

[0038] 11: outer layer portion on the main surface side;

[0039] 12: outer layer portion on the first main surface side;

[0040] 13: outer layer portion on the second main surface side;

[0041] 14: effective layer;

[0042] 15: first side outer layer;

[0043] 16: lateral outer layer of the second side;

[0044] 17: first end surface side outer layer portion;

[0045] 18: outer layer portion on the second end surface side;

[0046] 20: dielectric layer;

[0047] 21: inner dielectric layer;

[0048] 22: outer dielectric layer;

[0049] 30: internal electrode layer;

[0050] 31: first internal electrode layer;

[0051] 32: second internal electrode layer;

[0052] 33: First opposing portion;

[0053] 34: second opposing portion;

[0054] 35: 1st lead-out section;

[0055] 36: 2nd lead-out section;

[0056] 40: external electrode;

[0057] 41: 1st external electrode;

[0058] 42: second external electrode;

[0059] 50: base electrode layer;

[0060] 51: first base electrode layer;

[0061] 52: second base electrode layer;

[0062] 71: first plating layer;

[0063] 72: second plating layer;

[0064] 73: first nickel plating layer;

[0065] 74: second nickel plating layer;

[0066] 75: first tin plating layer;

[0067] 76: second tin plating layer;

[0068] 81: rare earth segregation area;

[0069] 82: aluminum segregation area;

[0070] 111: end of the first side;

[0071] 112: end of the second side;

[0072] 201: end portion in the width direction of the effective layer;

[0073] 202: central part of the effective layer;

[0074] 211: end evaluation area;

[0075] 212: Central evaluation area;

[0076] 311: area where internal electrodes exist;

[0077] 312: internal electrode cut-off region;

[0078] 811: rare earth segregation area;

[0079] L: length direction;

[0080] T: height direction;

[0081] W: width direction. DETAILED DESCRIPTION

[0082] (Multilayer Ceramic Capacitors)

[0083] A multilayer ceramic capacitor 1 according to an embodiment of the present disclosure will be described with reference to the drawings. Figure 1 This is a perspective view of the appearance of a multilayer ceramic capacitor 1 according to one embodiment of the present disclosure. Figure 2 yes Figure 1 101-101 cross-sectional view. Figure 3 yes Figure 2 102-102 cross-sectional view. Figure 4 yes Figure 2 103-103 cross-sectional view. Figure 5 yes Figure 2 104-104 cross-sectional view.

[0084] like Figure 1 As shown, the multilayer ceramic capacitor 1 is in a substantially rectangular parallelepiped shape. The multilayer ceramic capacitor 1 includes a multilayer body 2 having a substantially rectangular parallelepiped shape and a pair of external electrodes 40 disposed at both ends of the multilayer body 2 so as to be spaced apart from each other.

[0085] exist Figure 1 In FIG. 1 , arrow T indicates the height direction of the multilayer ceramic capacitor 1 and the multilayer body 2. The height direction T is also the thickness direction and the stacking direction of the multilayer ceramic capacitor 1 and the multilayer body 2. Figure 1 In FIG. 1 , arrow L indicates the longitudinal direction of the multilayer ceramic capacitor 1 and the multilayer body 2, which is perpendicular to the height direction T. Figure 1In FIG. 1 , arrow W indicates the width direction of the multilayer ceramic capacitor 1 and the laminate 2 , which is perpendicular to the height direction T and the length direction L. The pair of external electrodes 40 are respectively arranged at one end and the other end of the laminate 2 in the length direction L.

[0086] Figure 2 The section shown is called the LT section. Figure 3 The section shown is called the WT section. Figure 4 The cross-section shown and Figure 5 The section shown is called the LW section.

[0087] (Laminated body)

[0088] The two surfaces of the laminate 2 that are opposite to each other in the height direction T are referred to as the first main surface 3 and the second main surface 4. The two surfaces of the laminate that are opposite to each other in the length direction L that is perpendicular to the height direction T are referred to as the first end surface 7 and the second end surface 8. The two surfaces of the laminate 2 that are opposite to each other in the width direction W that is perpendicular to the height direction T and the length direction L are referred to as the first side surface 5 and the second side surface 6.

[0089] like Figure 1 As shown, the shape of the laminate 2 is a substantially rectangular parallelepiped. The length of the laminate 2 in the longitudinal direction L may not be longer than the length in the width direction W. The corners and ridges of the laminate 2 are preferably rounded. A corner is where three sides of the laminate intersect. A ridge is where two sides of the laminate intersect. Part or all of the surface of the laminate 2 may also have a concave-convex shape.

[0090] The size of the laminate 2 is not limited. The preferred length of the laminate 2 in the longitudinal direction L is 0.2 mm to 6 mm. The preferred length of the laminate 2 in the height direction T is 0.05 mm to 5 mm. The preferred length of the laminate 2 in the width direction W is 0.1 mm to 5 mm.

[0091] (Division in the height direction)

[0092] like Figure 2 as well as Figure 3 As shown, the laminate 2 is divided into an inner layer portion 10 and a main surface side outer layer portion 11 in the height direction T. The main surface side outer layer portion 11 includes a first main surface side outer layer portion 12 and a second main surface side outer layer portion 13. The first main surface side outer layer portion 12 and the second main surface side outer layer portion 13 are located so as to sandwich the inner layer portion 10 in the height direction T. In other words, the laminate 2 is divided into the first main surface side outer layer portion 12, the inner layer portion 10, and the second main surface side outer layer portion 13.

[0093] (Dielectric layer)

[0094] The inner layer portion 10 includes a plurality of dielectric layers 20 and a plurality of internal electrode layers 30 alternately stacked in the height direction T. The inner layer portion 10 includes the internal electrode layer 30 located closest to the first principal surface 3 in the height direction T to the internal electrode layer 30 located closest to the second principal surface 4. In the inner layer portion 10, the plurality of internal electrode layers 30 are arranged opposite each other with the dielectric layers 20 interposed therebetween. The inner layer portion 10 is the portion that generates electrostatic capacitance and essentially functions as a capacitor. The dielectric layers 20 included in the inner layer portion 10 are referred to as inner dielectric layers 21. The dielectric layers 20 included in the outer layer portion 12 on the first principal surface side and the dielectric layers 20 included in the outer layer portion 13 on the second principal surface side are referred to as outer dielectric layers 22.

[0095] The plurality of dielectric layers 20 are composed of a dielectric material. The dielectric material includes a material having a perovskite structure containing at least one of calcium, zirconium, and strontium. More specifically, the dielectric material is a temperature compensation dielectric material with a low rate of capacitance change due to temperature. The dielectric material contains at least one of calcium, zirconium, and strontium as a main component. For example, in the dielectric material, at least one of calcium and strontium constitutes the A site of the perovskite structure (ABO3), and at least one of zirconium, titanium, and hafnium constitutes the B site of the perovskite structure.

[0096] Specific examples of the main component of the dielectric material include dielectric ceramics containing calcium titanate, strontium titanate, titanium oxide, calcium zirconate, etc. The multilayer ceramic capacitor 1 of the present embodiment is a temperature compensation multilayer ceramic capacitor.

[0097] Dielectric materials are materials with additives added to these main components. Examples of additives include, in addition to the aforementioned hafnium, silicon, and calcium, oxides of rare earth elements such as manganese, magnesium, dysprosium, chromium, or vanadium, samarium, europium, gadolinium, terbium, holmium, erbium, thulium, ytterbium, and yttrium; oxides of cobalt, nickel, lithium, boron, sodium, potassium, and silicon; and glass. Among these, dysprosium and yttrium are particularly preferred rare earth elements.

[0098] The preferred thickness of dielectric layer 20 is 0.2 μm to 10 μm. The preferred number of laminated dielectric layers 20 is 15 to 1200. The number of dielectric layers 20 is the sum of the number of inner dielectric layers 21 and the number of outer dielectric layers 22.

[0099] (Internal electrode layer)

[0100] The plurality of internal electrode layers 30 include a plurality of first internal electrode layers 31 and a plurality of second internal electrode layers 32. The first internal electrode layers 31 and the second internal electrode layers 32 are alternately arranged in the height direction T with the dielectric layer 20 interposed therebetween. The first internal electrode layers 31 extend toward the first end surface 7, and the second internal electrode layers 32 extend toward the second end surface 8.

[0101] like Figure 4 As shown, the first internal electrode layer 31 is divided into a first opposing portion 33 and a first lead portion 35. The first opposing portion 33 is a portion that faces the second internal electrode layer 32 with the dielectric layer 20 interposed therebetween. The first lead portion 35 is a portion that extends from the first opposing portion 33 toward the first end surface 7. The first lead portion 35 is exposed at the first end surface 7.

[0102] like Figure 5 As shown, the second internal electrode layer 32 is divided into a second opposing portion 34 and a second lead portion 36. The second opposing portion 34 is a portion that faces the first internal electrode layer 31 with the dielectric layer 20 interposed therebetween. The second lead portion 36 is a portion that extends from the second opposing portion 34 toward the second end surface 8. The second lead portion 36 is exposed at the second end surface 8.

[0103] In the multilayer ceramic capacitor 1 , the first opposing portion 33 and the second opposing portion 34 face each other via the dielectric layer 20 , thereby forming capacitance. As a result, the multilayer ceramic capacitor 1 exhibits capacitor characteristics.

[0104] The shapes of the first opposing portion 33 and the second opposing portion 34 are not limited. Preferred shapes for the first opposing portion 33 and the second opposing portion 34 are rectangular. Similarly, the shapes of the first lead portion 35 and the second lead portion 36 are not limited. Preferred shapes for the first lead portion 35 and the second lead portion 36 are rectangular. In the aforementioned rectangular shape, the corners of the rectangle may be rounded. The corners of the rectangle may also be inclined.

[0105] The length of the first opposing portion 33 in the width direction W and the length of the first lead portion 35 in the width direction W may be the same. The length of the first opposing portion 33 in the width direction W and the length of the first lead portion 35 in the width direction W may be shorter. The length of the second opposing portion 34 in the width direction W and the length of the second lead portion 36 in the width direction W may be the same. The length of the second opposing portion 34 in the width direction W and the length of the second lead portion 36 in the width direction W may be shorter.

[0106] Examples of materials for the first and second internal electrode layers 31, 32 include metals such as nickel, copper, silver, palladium, and gold, and conductive materials such as alloys containing at least one of these metals. When alloys are used, examples of materials for the first and second internal electrode layers 31, 32 include alloys of silver and palladium.

[0107] The preferred thickness of each of the first internal electrode layer 31 and the second internal electrode layer 32 is 0.2 μm to 2.0 μm. The preferred total number of first internal electrode layers 31 and second internal electrode layers 32 is 15 to 1000.

[0108] (Main surface side outer layer)

[0109] like Figure 2 as well as Figure 3 As shown, the portion comprising the aggregate of the plurality of dielectric layers 20 located between the first principal surface 3 and the internal electrode layer 30 closest to the first principal surface 3 is referred to as the first principal surface-side outer layer portion 12. The first principal surface-side outer layer portion 12 is located on the first principal surface 3 side of the laminate 2. The portion comprising the aggregate of the plurality of dielectric layers 20 located between the second principal surface 4 and the internal electrode layer 30 closest to the second principal surface 4 is referred to as the second principal surface-side outer layer portion 13. The second principal surface-side outer layer portion 13 is located on the second principal surface 4 side of the laminate 2. The dielectric layers 20 used in both the first principal surface-side outer layer portion 12 and the second principal surface-side outer layer portion 13 can be the same dielectric layers as the dielectric layers 20 used in the inner layer portion 10. The material of the inner dielectric layer 21 and the material of the outer dielectric layer 22 can be the same.

[0110] (Effective layer)

[0111] The portion where the first opposing portion 33 of the first internal electrode layer 31 and the second opposing portion 34 of the second internal electrode layer 32 face each other is called the effective layer portion 14. The effective layer portion 14 is a portion where the dielectric layer 20 and the internal electrode layer 30 are alternately stacked. The effective layer portion 14 is a portion of the internal layer portion 10. Figure 4 as well as Figure 5 , the extent of the effective layer portion 14 in the width direction W and the length direction L is shown. The effective layer portion 14 is the portion of the inner layer portion 10 excluding the side spacing and the end spacing described later. The effective layer portion 14 is also referred to as a capacitance forming portion or a capacitor effective portion.

[0112] (Division in the width direction W)

[0113] The laminate 2 is divided into a first side outer layer portion 15, an effective layer portion 14, and a second side outer layer portion 16 in the width direction W. The first side outer layer portion 15 is a portion including the dielectric layer 20 located between the effective layer portion 14 and the first side 5. The second side outer layer portion 16 is a portion including the dielectric layer 20 located between the effective layer portion 14 and the second side 6. Figure 3 、 Figure 4 as well as Figure 5, the ranges of the first side outer layer portion 15, the effective layer portion 14, and the second side outer layer portion 16 in the width direction W are shown. The first side outer layer portion 15 and the second side outer layer portion 16 are referred to as W intervals or lateral intervals.

[0114] (Division in the length direction L)

[0115] The laminate 2 is divided into a first end face side outer layer portion 17, an effective layer portion 14, and a second end face side outer layer portion 18 in the longitudinal direction L. The first end face side outer layer portion 17 is a portion including the dielectric layer 20 and the first lead portion 35 located between the effective layer portion 14 and the first end face 7. The first end face side outer layer portion 17 is a collection of the portions of the multilayer dielectric layer 20 on the first end face 7 side and the multilayer first lead portion 35. The second end face side outer layer portion 18 is a portion including the dielectric layer 20 and the second lead portion 36 located between the effective layer portion 14 and the second end face 8. The second end face side outer layer portion 18 is a collection of the portions of the multilayer dielectric layer 20 on the second end face 8 side and the multilayer second lead portion 36. Figure 2 、 Figure 4 as well as Figure 5 , the ranges of the first end surface side outer layer portion 17, the effective layer portion 14, and the second end surface side outer layer portion 18 in the longitudinal direction L are shown. The first end surface side outer layer portion 17 and the second end surface side outer layer portion 18 are referred to as L intervals or end intervals.

[0116] (External electrode)

[0117] The external electrodes 40 include a first external electrode 41 and a second external electrode 42. The first external electrode 41 is disposed on the first end face 7 side of the stacked body 2. The second external electrode 42 is disposed on the second end face 8 side of the stacked body 2.

[0118] The first external electrode 41 and the second external electrode 42 have the same basic structure and have shapes that are substantially plane-symmetrical with respect to a WT cross section at the center in the longitudinal direction L of the multilayer ceramic capacitor 1 .

[0119] The first external electrode 41 is disposed on the first end surface 7. The first external electrode 41 contacts the first lead portion 35 of each of the plurality of first internal electrode layers 31 exposed on the first end surface 7. The first external electrode 41 is electrically connected to the plurality of first internal electrode layers 31. The first external electrode 41 may also be disposed on a portion of the first principal surface 3, a portion of the second principal surface 4, a portion of the first side surface 5, and a portion of the second side surface 6. In this embodiment, the first external electrode 41 is formed to extend from the first end surface 7 to a portion of the first principal surface 3, a portion of the second principal surface 4, a portion of the first side surface 5, and a portion of the second side surface 6.

[0120] The second external electrode 42 is disposed on the second end surface 8. The second external electrode 42 contacts the second lead portion 36 of each of the plurality of second internal electrode layers 32 exposed on the second end surface 8. The second external electrode 42 is electrically connected to the plurality of second internal electrode layers 32. The second external electrode 42 may also be disposed on a portion of the first principal surface 3, a portion of the second principal surface 4, a portion of the first side surface 5, and a portion of the second side surface 6. In this embodiment, the second external electrode 42 is formed so as to extend from the second end surface 8 to a portion of the first principal surface 3, a portion of the second principal surface 4, a portion of the first side surface 5, and a portion of the second side surface 6.

[0121] Within the laminate 2, the first opposing portion 33 of the first internal electrode layer 31 and the second opposing portion 34 of the second internal electrode layer 32 oppose each other via the dielectric layer 20, thereby forming a capacitor. Consequently, capacitor characteristics are exhibited between the first external electrode 41 connected to the first internal electrode layer 31 and the second external electrode 42 connected to the second internal electrode layer 32.

[0122] (Base electrode layer)

[0123] like Figure 2 、 Figure 4 as well as Figure 5 As shown, the first external electrode 41 includes a first foundation electrode layer 51 and a first plating layer 71. The first plating layer 71 is disposed on the first foundation electrode layer 51. The second external electrode 42 includes a second foundation electrode layer 52 and a second plating layer 72. The second plating layer 72 is disposed on the second foundation electrode layer 52.

[0124] The first foundation electrode layer 51 is disposed on the first end surface 7. The first foundation electrode layer 51 is in contact with the first lead portion 35 of each of the plurality of first internal electrode layers 31 exposed on the first end surface 7. The first foundation electrode layer 51 is formed so as to extend from the first end surface 7 to a portion of the first principal surface 3, a portion of the second principal surface 4, a portion of the first side surface 5, and a portion of the second side surface 6.

[0125] The second foundation electrode layer 52 is disposed on the second end surface 8. The second foundation electrode layer 52 is in contact with the second lead portion 36 of each of the plurality of second internal electrode layers 32 exposed on the second end surface 8. The second foundation electrode layer 52 is formed so as to extend from the second end surface 8 to a portion of the first principal surface 3, a portion of the second principal surface 4, a portion of the first side surface 5, and a portion of the second side surface 6.

[0126] The first base electrode layer 51 and the second base electrode layer 52 are sintered layers. The sintered layers preferably contain a metal component. In addition to the metal component, the sintered layers preferably also contain at least one of a glass component and a ceramic component. The metal component, for example, includes at least one selected from copper, nickel, silver, palladium, an alloy of silver and palladium, gold, etc. The glass component, for example, includes at least one selected from boron, silicon, barium, magnesium, aluminum, lithium, etc. The ceramic component can be the same type of ceramic material as the dielectric layer 20. The ceramic component can also be a different type of ceramic material from the dielectric layer 20. The ceramic component, for example, includes at least one selected from barium titanate, calcium titanate, a mixed crystal material in which a portion of the barium in barium titanate is replaced with calcium, strontium titanate, calcium zirconate, etc.

[0127] An example of a sintered layer is a layer formed by applying a conductive paste containing glass and metal to a laminate and sintering it. The sintered layer is formed by simultaneously sintering a pre-sintered laminated sheet containing multiple internal electrode layers and multiple dielectric layers, which is the raw material of the laminate, and the conductive paste applied to the laminated sheet. Alternatively, the sintered layer is formed by sintering the laminated sheet to obtain a laminate, and then applying a conductive paste to the laminate and sintering it. In the case where the conductive paste is sintered after the laminate is obtained, the sintered layer is preferably formed by sintering a conductive paste to which a ceramic material has been added instead of the glass component. When a conductive paste to which a ceramic material has been added is used, the added ceramic material is preferably a ceramic material of the same type as the dielectric layer. The sintered layer can also be multilayered.

[0128] As an example of a preferred thickness of the first foundation electrode layer 51 in the longitudinal direction L on the first end face 7 , the central portion in the height direction T and the width direction W of the first foundation electrode layer 51 is approximately 10 μm to 200 μm.

[0129] As an example of a preferred thickness of the second foundation electrode layer 52 in the longitudinal direction L on the second end surface 8 , the central portion in the height direction T and the width direction W of the second foundation electrode layer 52 is approximately 10 μm to 200 μm.

[0130] In the case where the first base electrode layer 51 is also provided on a portion of at least one of the first main surface 3 or the second main surface 4, as an example of a preferred thickness in the height direction T of the first base electrode layer 51 provided in the portion, the central portion in the length direction L and the width direction W of the first base electrode layer 51 provided in the portion is greater than 3 μm and less than 40 μm.

[0131] In the case where the first base electrode layer 51 is also provided on a portion of at least one surface of the first side surface 5 or the second side surface 6, as an example of a preferred thickness in the width direction W of the first base electrode layer 51 provided in the portion, the central portion in the length direction L and the height direction T of the first base electrode layer 51 provided in the portion is greater than 3 μm and less than 40 μm.

[0132] In the case where the second base electrode layer 52 is also provided on a portion of at least one of the first main surface 3 or the second main surface 4, as an example of a preferred thickness in the height direction T of the second base electrode layer 52 provided in the portion, the central portion in the length direction L and the width direction W of the second base electrode layer 52 provided in the portion is greater than 3 μm and less than 40 μm.

[0133] In the case where the second base electrode layer 52 is also provided on a portion of at least one surface of the first side surface 5 or the second side surface 6, as an example of a preferred thickness in the width direction W of the second base electrode layer 52 provided in the portion, the central portion in the length direction L and the height direction T of the second base electrode layer 52 provided in the portion is greater than 3 μm and less than 40 μm.

[0134] The first plating layer 71 is arranged to cover the first foundation electrode layer 51 . The second plating layer 72 is arranged to cover the second foundation electrode layer 52 .

[0135] The first plating layer 71 and the second plating layer 72 may include, for example, at least one selected from copper, nickel, tin, silver, palladium, an alloy of silver and palladium, gold, and the like. The first plating layer 71 and the second plating layer 72 may each be formed of multiple layers. A preferred structure of the first plating layer 71 and the second plating layer 72 is a two-layer structure in which a tin plating layer is formed on a nickel plating layer.

[0136] The first plating layer 71 is arranged to cover the first base electrode layer 51. In this embodiment, the first plating layer 71 includes a first nickel plating layer 73 and a first tin plating layer 75. The first tin plating layer 75 is located on the first nickel plating layer 73.

[0137] The second plating layer 72 is arranged to cover the second base electrode layer 52. In this embodiment, the second plating layer 72 includes a second nickel plating layer 74 and a second tin plating layer 76. The second tin plating layer 76 is located on the second nickel plating layer 74.

[0138] The nickel plating layer prevents the first and second base electrode layers 51 and 52 from being corroded by solder when mounting the multilayer ceramic capacitor 1. The tin plating layer improves the wettability of the solder when mounting the multilayer ceramic capacitor 1. The tin plating layer facilitates mounting the multilayer ceramic capacitor 1. The first nickel plating layer 73, the first tin plating layer 75, the second nickel plating layer 74, and the second tin plating layer 76 each preferably have a thickness of 2 μm or more and 10 μm or less.

[0139] The external electrode 40 may also include a conductive resin layer containing conductive particles and a thermosetting resin. When the external electrode 40 includes a conductive resin layer, the conductive resin layer may be arranged to cover the sintered layer. When the conductive resin layer is arranged to cover the sintered layer, the conductive resin layer is arranged between the sintered layer and the plated layer. The sintered layer corresponds to the first base electrode layer 51 and the second base electrode layer 52. The plated layer corresponds to the first plated layer 71 and the second plated layer 72. The conductive resin layer may completely cover the sintered layer. Alternatively, the conductive resin layer may cover a portion of the sintered layer.

[0140] A conductive resin layer composed of a thermosetting resin is more flexible than a conductive layer composed of a plated film or a fired product of a conductive paste. Therefore, when a multilayer ceramic capacitor is subjected to physical shock or shock caused by thermal cycling, the conductive resin layer functions as a buffer layer. Consequently, the conductive resin layer suppresses cracks in the multilayer ceramic capacitor.

[0141] Examples of metals that constitute the conductive particles include silver, copper, nickel, tin, bismuth, or alloys containing at least two of these metals. The conductive particles preferably contain silver. An example of conductive particles is silver metal powder. Silver has the lowest resistivity among metals. Silver is suitable for electrode materials. Silver is a precious metal. Silver is not easily oxidized. Silver has high weather resistance. For these reasons, silver metal powder is suitable as the conductive particles.

[0142] The conductive particles may also be metal powder coated with silver. When using conductive particles coated with silver, the metal powder is preferably copper, nickel, tin, bismuth, or an alloy thereof. To ensure the properties of silver while reducing the cost of the base metal, silver-coated metal powder is preferably used.

[0143] The conductive particles may also be copper or nickel particles subjected to an oxidation prevention treatment. Alternatively, the conductive particles may be metal powders coated with tin, nickel, or copper. When using metal powders coated with tin, nickel, or copper, the metal powders are preferably silver, copper, nickel, tin, bismuth, or alloy powders containing at least two of these metals.

[0144] The shape of the conductive particles is not limited. Examples of the conductive particle shape include spherical and flat shapes. It is preferable to use a mixture of spherical metal powder and flat metal powder.

[0145] The conductive particles contained in the conductive resin layer mainly play a role in ensuring the electrical conductivity of the conductive resin layer. The plurality of conductive particles are in contact with each other, thereby forming a current path inside the conductive resin layer.

[0146] Examples of the resin constituting the conductive resin layer may include at least one selected from various well-known thermosetting resins such as epoxy resin, phenolic resin, urethane resin, silicone resin, and polyimide resin. Among these, epoxy resin is particularly suitable. Epoxy resin has excellent heat resistance, moisture resistance, and adhesion. The resin of the conductive resin layer preferably contains a curing agent together with the thermosetting resin. When epoxy resin is used as the base resin, the curing agent for the epoxy resin may also be various well-known compounds such as phenols, amines, acid anhydrides, imidazoles, active esters, and amide-imides.

[0147] The conductive resin layer may be formed of a plurality of layers. The thickness of the thickest portion of the conductive resin layer is preferably 10 μm to 150 μm.

[0148] The above is the basic structure of the multilayer ceramic capacitor 1. The preferred length of the multilayer ceramic capacitor 1, including the laminate 2 and the external electrodes 40, in the longitudinal direction L is 0.2 mm to 6 mm. The preferred length of the multilayer ceramic capacitor 1 in the height direction T is 0.05 mm to 5 mm. The preferred length of the multilayer ceramic capacitor 1 in the width direction W is 0.1 mm to 5 mm.

[0149] (Segregation of rare earth elements)

[0150] In the multilayer ceramic capacitor 1 of the present embodiment, the segregation of the rare earth elements is not uniform within the laminate 2. Figure 6A as well as Figure 6B etc. for explanation. Figure 6A yes Figure 2 106-106 cross-sectional view. Figure 6B yes Figure 2 105-105 cross-sectional view.

[0151] (Effective layer width direction end portion and effective layer center portion)

[0152] like Figure 6A as well as Figure 6B As shown, the laminate 2 has an effective layer width direction end portion 201 and an effective layer center portion 202. The so-called effective layer width direction end portion 201 is as shown in FIG. Figure 6AAs shown, it refers to the portion near the end 111 of the first side surface 5 of the effective layer portion 14 and the portion near the end 112 of the second side surface 6 of the effective layer portion 14 in the WT cross section. On the other hand, the so-called effective layer central portion 202 is as shown in FIG. Figure 6B The reference numeral WT indicates the center portion of the effective layer portion 14 in the width direction W in the WT cross section.

[0153] (Effective layer width direction end)

[0154] First, refer to Figure 6A Next, the effective layer width direction end portion 201 will be described. The effective layer width direction end portion 201 is a portion of the effective layer portion 14 surrounded by the lines 251 and 252 and a portion of the effective layer portion 14 surrounded by the lines 253 and 254.

[0155] Line 251 is located at end 111 on the first side surface 5 side of effective layer portion 14. Line 252 is a line displaced 20 μm in parallel from line 251 toward second side surface 6. In other words, the distance between lines 251 and 252 (i.e., distance 221) is 20 μm.

[0156] Line 254 is located at end 112 on the second side face 6 side of effective layer portion 14. Line 253 is parallelly displaced 20 μm from line 254 toward first side face 5. In other words, the distance between line 253 and line 254 is 20 μm.

[0157] As described above, the effective layer width direction end portions 201 are portions of the effective layer portion 14 extending from respective ends in the width direction W of the effective layer portion 14 to 20 μm inward of the effective layer portion 14 .

[0158] The above description is made with reference to a cross section of the effective layer portion 14. The effective layer width direction end portion 201 is located at the same position as the effective layer portion 14 in the longitudinal direction L. Figure 6A The positions shown are identical positions consecutively.

[0159] (Center of the effective layer)

[0160] Next, refer to Figure 6B Next, we will describe the effective layer center portion 202. Effective layer center portion 202 is the portion of effective layer portion 14 surrounded by lines 271 and 272. Lines 271 and 272 extend from the center of effective layer portion 14 in width direction W, with a distance of 20 μm between them. In other words, distance 231 between lines 271 and 272 is 20 μm.

[0161] As described above, the effective layer center portion 202 is a portion having a width of 20 μm at the center portion in the width direction W of the effective layer portion 14 .

[0162] The above description is made with reference to a cross section of the effective layer portion 14. The effective layer central portion 202 is located at the same position as the effective layer portion 14 in the longitudinal direction L. Figure 6B The positions shown are identical positions consecutively.

[0163] (Rare earth segregation area)

[0164] In the multilayer ceramic capacitor 1 of the present embodiment, the laminate 2 has a rare earth segregation region. The rare earth segregation region refers to a region where rare earth elements are segregated.

[0165] Furthermore, in the multilayer ceramic capacitor 1 of the present embodiment, in the WT cross section, the segregation amount of the rare earth element in the rare earth segregation region in the effective layer width direction end portion 201 is in the relationship of the effective layer center portion 202 > the effective layer width direction end portion 201. Figure 7A 、 Figure 7B 、 Figure 8A as well as Figure 8B Provide explanation.

[0166] (Evaluation area at the end and evaluation area at the center)

[0167] First, the evaluation areas in the effective layer width direction end portion 201 and the effective layer center portion 202 are described. The so-called evaluation area refers to the measurement range when measuring the characteristics of the effective layer width direction end portion 201 and the effective layer center portion 202, such as the segregation amount of rare earth elements. The evaluation area of ​​the effective layer width direction end portion 201 is set as the end evaluation area 211. The evaluation area of ​​the effective layer center portion 202 is set as the center portion evaluation area 212. Figure 6A as well as Figure 6B As shown, the end evaluation region 211 and the central evaluation region 212 are square in shape. The length of one side of the square is 20 μm. The position of the end evaluation region 211 and the central evaluation region 212 in the height direction T is the center position of the effective layer portion 14 in the height direction T.

[0168] Figure 7A This is an electron microscope image of the end evaluation region 211 . Figure 7B This is an electron microscope image of the central evaluation region 212 . Figure 8A This is a field emission wavelength dispersive X-ray spectrometry (FE-WDX: Field Emission-Wavelength-dispersive X-ray Spectrometry) image of the end evaluation region 211 . Figure 8BThis is the FE-WDX image of the central evaluation area 212 . Figure 8A as well as Figure 8B The segregation of rare earth elements is shown. Figure 7A The image and Figure 8A The image shown is an image of the same position of the WT cross section as the object. Figure 7B The image and Figure 8B The images shown are images taken at the same position of the WT cross section.

[0169] exist Figure 8A as well as Figure 8B The white part in the figure is the rare earth segregation area 81. Figure 8A In the end evaluation area 211 shown, although rare earth segregation areas 81 can be seen, their number is small. Figure 8B In the central evaluation area 212 shown, it can be observed that Figure 8A The end evaluation region 211 shown is a rare earth segregation region 81 with many parts.

[0170] In addition, Figure 8B In the central evaluation area 212 shown, Figure 8A Compared with the end evaluation area 211 shown, a large rare earth segregation area 81 is easily observed. Figure 8A In the end evaluation region 211 shown in FIG. 8 , the rare earth segregation region 811 indicated by the arrow 811 is a rare earth segregation region 81 having a relatively large area. Figure 8B In the central evaluation area 212 shown in FIG. 8 , as shown by arrows 812 and 813, Figure 8A Compared to the end evaluation region 211 shown, more relatively large rare earth segregation regions 811 are observed. Specifically, the rare earth element segregation amount in the rare earth segregation region 81 located in the effective layer width direction end 201 in the WT cross section near the boundary between the L interval and the effective layer portion 14 is greater than the rare earth element segregation amount in the rare earth segregation region 81 located in the effective layer center portion 202 in the WT cross section at the center in the longitudinal direction L. The region near the boundary between the L interval and the effective layer portion 14 refers to the portion near the end of the effective layer portion 14 on the first end face 7 side and the portion near the end of the effective layer portion 14 on the second end face 8 side in the LT cross section.

[0171] As described above, in the multilayer ceramic capacitor 1 of the present embodiment, in the WT cross section, relative to the segregation amount of rare earth elements in the rare earth segregation region 81 existing in the end portion 201 in the width direction of the effective layer, the segregation amount of rare earth elements in the rare earth segregation region 81 existing in the central portion 202 of the effective layer is in the relationship of effective layer central portion 202 > effective layer width direction end portion 201.

[0172] The above equation means that the amount of rare earth element segregation in the rare earth segregation region 81 at the effective layer widthwise end portion 201 is less than the amount of rare earth element segregation in the rare earth segregation region 81 at the effective layer center portion 202. By maintaining the above relationship between the rare earth segregation regions 81 at the effective layer widthwise end portion 201 and the effective layer center portion 202, the reliability of the multilayer ceramic capacitor 1 of this embodiment can be improved. This will be explained below.

[0173] Assume that the atomic concentration of rare earth elements contained in the effective layer width direction end portions 201 is equal to the atomic concentration of rare earth elements contained in the effective layer center portion 202. Generally speaking, the reliability of the effective layer width direction end portions 201 tends to decrease compared to the reliability of the effective layer center portion 202. In the multilayer ceramic capacitor 1 of this embodiment, the amount of rare earth element segregation in the effective layer width direction end portions 201 is less than the amount of rare earth element segregation in the effective layer center portion 202. A smaller amount of rare earth element segregation means a larger amount of rare earth elements solid-dissolved in the dielectric layer 20. As such, in the multilayer ceramic capacitor 1 of this embodiment, a larger amount of rare earth elements solid-dissolved in the dielectric layer 20 is achieved in the effective layer width direction end portions 201. Therefore, the reliability of the effective layer width direction end portions 201 can be improved.

[0174] Furthermore, in the multilayer ceramic capacitor 1 of this embodiment, the segregation of the rare earth element in the effective layer center portion 202 is relatively high. In other words, the segregation of the rare earth element in the dielectric layer 20 is relatively low. Therefore, the temperature characteristics of the multilayer ceramic capacitor 1 can be maintained.

[0175] As described above, the multilayer ceramic capacitor 1 of the present embodiment can improve high-temperature reliability while maintaining temperature characteristics.

[0176] (Segregation of rare earth elements)

[0177] Here, the ratio of the segregation amount of rare earth elements in the effective layer center portion 202 to the segregation amount of rare earth elements in the effective layer widthwise end portions 201 is preferably 2 to 4 times. The above configuration can further improve high-temperature reliability.

[0178] When the ratio is less than 2 times, the effect of improving high-temperature reliability is reduced.

[0179] On the other hand, when the ratio is greater than 4 times, the dielectric material becomes difficult to sinter, and the growth of the dielectric particles is suppressed. As a result, the dielectric constant of the dielectric layer 20 decreases, and the capacitance of the multilayer ceramic capacitor 1 decreases.

[0180] Furthermore, if the segregation amount of the rare earth element exceeds a predetermined value and increases, high-temperature reliability will decrease instead.

[0181] The ratio of the segregation amount of the rare earth element in the effective layer central portion 202 to the segregation amount in the effective layer width direction end portions 201 is more preferably 3 times.

[0182] (Aluminum segregation area)

[0183] The multilayer ceramic capacitor 1 of this embodiment has an aluminum segregation region 82 in the laminate 2. The aluminum segregation region 82 refers to a region where aluminum is segregated in the laminate 2. In the multilayer ceramic capacitor 1 of this embodiment, the aluminum segregation region 82 exists at the widthwise end portions 201 of the effective layer and does not exist in the central portion 202 of the effective layer. Figure 9A as well as Figure 9B Provide explanation.

[0184] Figure 9A It is the FE-WDX image of the edge evaluation area 211 . Figure 9B This is the FE-WDX image of the central evaluation area 212 . Figure 9A as well as Figure 9B The segregation of aluminum is shown. Figure 7A The image and Figure 9A The image shown is an image of the same position of the WT cross section as the object. Figure 7B The image and Figure 9B The image shown is an image of the same position of the WT cross section as the object. Figure 9A The white portion in the middle is the aluminum segregation region 82 .

[0185] In the end evaluation area 211, as Figure 9A As shown by arrows 821 and 822, there are multiple aluminum segregation regions 82. In contrast, in the central evaluation region 212, as shown in FIG. Figure 9B As shown, there is no aluminum segregation region 82 .

[0186] Effective layer widthwise end portions 201 are portions where dielectric layer 20 is likely to become thinner and where high-temperature reliability is likely to decline. In the multilayer ceramic capacitor 1 of this embodiment, aluminum selectively segregates at effective layer widthwise end portions 201. Consequently, the high-temperature reliability of the multilayer ceramic capacitor 1 is improved.

[0187] (Internal electrode presence area and internal electrode cutoff area)

[0188] In the multilayer ceramic capacitor 1 of this embodiment, as Figure 7A as well as Figure 7B As shown, the internal electrode layer 30 includes an internal electrode existing region 311 and an internal electrode cutoff region 312 . Furthermore, the aluminum segregation region 82 exists in the internal electrode cutoff region 312 in the end evaluation region 211 .

[0189] The internal electrode existing region 311 refers to a region where the internal electrode layer 30 exists continuously in the width direction W in the WT cross section. The internal electrode interrupted region 312 refers to a region where the internal electrode layer 30 is interrupted in the width direction W in the WT cross section. In the internal electrode interrupted region 312, the material constituting the internal electrode layer 30 does not exist. In the internal electrode interrupted region 312, the material constituting the internal electrode layer 30 is missing.

[0190] In the multilayer ceramic capacitor 1 of the present embodiment, the aluminum segregation region 82 exists in the internal electrode dividing region 312 in the end evaluation region 211. With this structure, the effect of improving high-temperature reliability can be further obtained.

[0191] In the multilayer ceramic capacitor 1 of this embodiment, aluminum segregates in the missing portions of the internal electrode layer 30 at the effective layer widthwise end portions 201. Specifically, the missing portions of the internal electrode layer 30 are filled with aluminum segregation regions 82. This prevents the electric field from concentrating in the missing portions of the internal electrode layer 30, where the electric field would otherwise be concentrated. Consequently, the reliability of the multilayer ceramic capacitor 1 can be improved. Furthermore, aluminum typically segregates in the form of aluminum oxide.

[0192] (Definition and determination method of rare earth segregation)

[0193] Rare earth element segregation can be defined using counts per second (cps), which is the number of X-ray photons per unit time obtained by WDX. Specifically, based on FE-WDX element mapping, the number of cells with a rare earth element count of 20 cps or more is defined as the rare earth element segregation.

[0194] The specific measurement method is as follows.

[0195] The periphery of the measurement sample is impregnated with epoxy resin and then cured.

[0196] The measurement sample including the epoxy resin is polished in a direction in which a cross section parallel to the width direction W and the height direction T can be observed.

[0197] Only the first end surface side outer layer portion 17 or the second end surface side outer layer portion 18 (ie, the L interval) is mirror-polished. Thus, the cross section of the end in the longitudinal direction L of the effective layer portion 14 is exposed. Figure 2 106-106 sectional view (ie, Figure 6A ) shows the cross section.

[0198] The mirror polishing is further advanced until the multilayer ceramic capacitor 1 reaches its center in the longitudinal direction L. This exposes the cross section of the center portion of the effective layer portion 14 in the longitudinal direction L. Figure 2 105-105 sectional view (ie, Figure 6B ) shows the cross section.

[0199] The surface of each exposed cross section was coated with gold at 30 mA for 60 seconds.

[0200] Element mapping was performed using FE-WDX (device name: EPMA-8050G (product name)).

[0201] The observation area for elemental mapping is the end evaluation region 211 of the effective layer width direction end 201 in the cross section of the effective layer portion polished only at intervals L in the longitudinal direction L. On the other hand, the observation area for elemental mapping is the central evaluation region 212 of the effective layer central portion 202 in the cross section polished to the central position in the longitudinal direction L of the multilayer ceramic capacitor 1.

[0202] The observation conditions were set to 3300x magnification, 15kV acceleration voltage, 240×240 pix image size, 45ms / pix integration time, and 50nA beam current. The number of counts (unit: cps) for each rare earth element was digitized. At this time, cells with a value of 20 cps or more were defined as segregation, and the number of such cells was counted in both the end evaluation region 211 and the central evaluation region 212. The region defined as segregation was the segregation region. The number of counts in the end evaluation region 211 was set as P. W The number of counts in the central evaluation area 212 is set to P C The field of view for measurement was set to 20 μm×20 μm.

[0203] Aluminum segregation was also evaluated in the same manner.

[0204] Material of the measurement sample

[0205] The dielectric material is a ceramic material having a perovskite structure containing barium, strontium, zirconium, titanium, hafnium, and calcium. Furthermore, silicon and dysprosium, a rare earth element, are added to the ceramic material.

[0206] (Examples and Comparative Examples)

[0207] Reference Figure 10 Examples and comparative examples will be described. Figure 10 is a diagram showing evaluation results of examples and comparative examples. Figure 10 The count P in the end evaluation area 211 is W The count number P in the central evaluation area 212 is expressed as C The ratio is set to "1" (except for Comparative Example 1 in which no segregation region was observed).

[0208] According to the manufacturing method described below, samples with varying segregation amounts were produced in batches, with manufacturing conditions adjusted to provide the samples for Examples 1 to 8 and Comparative Examples 1 and 2. The samples within each batch were produced under the same manufacturing conditions. For each of the Examples and Comparative Examples, three samples (n = 3) were taken from the same batch to measure segregation amounts, five samples (n = 5) were used to evaluate temperature characteristics, and 40 samples (n = 40) were prepared for high-temperature load reliability evaluation. Segregation amount measurements and temperature characteristics evaluations were performed using the average values ​​of the measurement and evaluation results.

[0209] <Temperature Characteristics>

[0210] The capacitance was measured at -55°C, 25°C, and 125°C, after 5 minutes had passed since the specified temperature was reached. The temperature coefficient α was calculated using the following formula, assuming the capacitance value at 25°C (reference temperature T1) was C1 and the capacitance value at each measured temperature T2 was C2.

[0211] α=(C2-C1) / {C1(T2-T1)}×10 6

[0212] Samples whose temperature coefficient α was within the range of 0±30 [ppm / °C] were rated as "○", and samples whose temperature coefficient α was outside the range of 0±30 [ppm / °C] but within the range of 0±60 [ppm / °C] were rated as "△". Calculations were performed on five samples each of the Examples and Comparative Examples, and the average value was used for the evaluation.

[0213] <High temperature load test>

[0214] A high-temperature load test of each sample was carried out based on the HALT test method. In more detail, each sample was set in a special fixture as a single unit and placed in a high-temperature tank at a temperature of 150 [°C], and a DC current of 120% of the rated voltage was applied between a pair of external electrodes, and this state was maintained for 100 hours. Then, the samples that did not fail in the test were judged as "◎", the samples that failed in the test and had 1 to 3 failures in the test were judged as "○", and the samples that had more than 4 failures in the test were judged as "×". In addition, 40 samples of each embodiment and comparative example were tested.

[0215] High-temperature load reliability cannot be achieved when the segregation amount of the rare earth element in the rare earth segregation region does not satisfy the following order: effective layer center > effective layer width direction ends, as shown in Comparative Examples 1 and 2. Comparative Example 1 is an example in which no rare earth element is added.

[0216] Furthermore, as shown in Examples 8 to 10, the presence of aluminum segregation regions at the widthwise ends of the effective layer further improved high-temperature load reliability. Furthermore, in Examples 4 and 5, the ratio of the rare earth element segregation in the center of the effective layer relative to the widthwise ends exceeded five times. Therefore, it is speculated that the solid solution of rare earth elements was promoted at the widthwise ends of the effective layer, resulting in a decrease in temperature characteristics. The ratio of the rare earth element segregation in the center of the effective layer relative to the widthwise ends of the effective layer is preferably 2 times or more and 5 times or less, and more preferably 2 times or more and 4 times or less.

[0217] (Method for Manufacturing Multilayer Ceramic Capacitors)

[0218] A method for manufacturing a multilayer ceramic capacitor will be described. Note that the method for manufacturing a multilayer ceramic capacitor is not limited to the following method.

[0219] A dielectric sheet for dielectric layer 20 and a conductive paste for internal electrode layer 30 are prepared. Both the dielectric sheet for dielectric layer 20 and the conductive paste for internal electrode layer 30 contain a binder and a solvent. The binder and solvent may be known binders and solvents. An example of a paste made of a conductive material is one in which an organic binder and an organic solvent are added to metal powder.

[0220] Conductive paste for the internal electrode layer 30 is printed on the dielectric sheet using a printing plate designed to form the shape of the internal electrode layer 30. Examples of printing methods include screen printing and gravure printing. This prepares a dielectric sheet with a pattern for the first internal electrode layer 31 and a dielectric sheet with a pattern for the second internal electrode layer 32.

[0221] A predetermined number of dielectric sheets without a pattern of the internal electrode layer 30 printed thereon are stacked to form a portion that will become the first principal surface side outer layer portion 12 on the first principal surface 3 side. Dielectric sheets with a pattern of the first internal electrode layer 31 printed thereon and dielectric sheets with a pattern of the second internal electrode layer 32 printed thereon are then alternately stacked thereon to form a portion that will become the inner layer portion 10. A predetermined number of dielectric sheets without a pattern of the internal electrode layer 30 printed thereon are then stacked to form a portion that will become the second principal surface side outer layer portion 13 on the second principal surface 4 side. This results in a laminated sheet.

[0222] When preparing the dielectric sheet, using ABO3 as the main component of a dielectric material having a perovskite structure (A represents the element at the A site of the perovskite structure. B represents the element at the B site of the perovskite structure), the rare earth element is prepared so that the rare earth element content is between 0.5 mol% and 2.5 mol% when the element at the B site is set to 100 mol%. Furthermore, the rare earth element is dysprosium. This makes it easier to achieve a ratio of the segregation of rare earth elements in the rare earth segregation region 81 in the effective layer center 202 to that in the effective layer width direction end portion 201, relative to the segregation of rare earth elements in the rare earth segregation region 81 in the effective layer width direction end portion 201.

[0223] Furthermore, when preparing the dielectric sheet, 0.02 mol % to 1.0 mol % of aluminum oxide is added to the dielectric material to facilitate the presence of aluminum segregation regions at the widthwise ends of the effective layer.

[0224] Next, the laminated sheets are pressed in the height direction by isostatic pressing or the like, thereby producing a laminated block.

[0225] Next, the stacked block is cut into pieces of a predetermined size to obtain a plurality of stacked small pieces. The stacked small pieces may then be polished by barrel polishing or the like to round off the corners and ridges.

[0226] Next, the stacked small pieces are fired. This firing produces a stacked body. The preferred firing temperature is 900° C. or higher and 1400° C. or lower. The firing temperature can be varied depending on the materials of the dielectric and internal electrode layers.

[0227] Here, during the sintering process, the gas volume is adjusted during the maximum temperature hold so that the oxygen partial pressure at the end of the maximum temperature hold is higher than the oxygen partial pressure at the start of the maximum temperature hold. This makes it easier to achieve a ratio of the segregation of rare earth elements in the rare earth segregation region 81 in the effective layer center 202 relative to the segregation of rare earth elements in the rare earth segregation region 81 in the effective layer widthwise end 201. Furthermore, it is easier to achieve an aluminum segregation region in the effective layer widthwise end.

[0228] A conductive paste, which will become the base electrode layer 50, is applied to both end surfaces of the laminate 2. In this embodiment, the base electrode layer 50 is a sintered layer. The sintered layer can be formed by applying a conductive paste containing a glass component and a metal to the laminate 2 by a method such as dipping, followed by sintering. The sintering temperature is preferably between 700°C and 900°C.

[0229] Alternatively, the pre-fired laminated pieces and the conductive paste applied to the laminated pieces may be fired simultaneously. In this case, the sintered layer is preferably formed by sintering a conductive paste to which a ceramic material has been added in place of the glass component. In this case, the added ceramic material is preferably the same type as that used for dielectric layer 20. In this case, the conductive paste is applied to the pre-fired laminated pieces, and the laminated pieces and the conductive paste applied to the laminated pieces are sintered simultaneously to form a laminate 2 having a sintered layer formed thereon.

[0230] Then, a plating layer is formed on the surface of the base electrode layer 50 consisting of a sintered layer. In the present embodiment, a first plating layer 71 is formed on the surface of the first base electrode layer 51. A second plating layer 72 is formed on the surface of the second base electrode layer 52. In the present embodiment, a nickel plating layer and a tin plating layer are formed as plating layers. When performing the plating process, either electrolytic plating or electroless plating can be adopted. However, with respect to electroless plating, in order to increase the plating deposition speed, it is necessary to perform pretreatment using a catalyst, etc., and therefore there is a disadvantage of complicating the process. Therefore, electrolytic plating is generally preferred. The nickel plating layer and the tin plating layer are formed sequentially, for example, by drum plating.

[0231] When a conductive resin layer is provided, it can also be configured to cover the sintered layer. When a conductive resin layer is provided, a conductive resin paste containing a thermosetting resin and a metal component is applied to the sintered layer and then heat-treated at a temperature of 250 to 550°C or higher. This heat-cures the thermosetting resin to form the conductive resin layer. The heat treatment atmosphere is preferably an N2 atmosphere. To prevent scattering of the resin and oxidation of the various metal components, the oxygen concentration is preferably below 100 ppm.

[0232] According to the above-described manufacturing steps, the multilayer ceramic capacitor 1 can be manufactured.

[0233] <1>

[0234] A stacked ceramic capacitor having:

[0235] A laminate comprising a plurality of laminated dielectric layers and a plurality of laminated internal electrode layers, the laminate comprising a first principal surface and a second principal surface opposing each other in a height direction, a first side surface and a second side surface opposing each other in a width direction perpendicular to the height direction, and a first end surface and a second end surface opposing each other in a length direction perpendicular to the height direction and the width direction, the laminate comprising an effective layer portion and an outer layer portion, the effective layer portion being formed by alternately laminating the dielectric layers and the internal electrode layers, the outer layer portion being arranged so as to sandwich the effective layer portion from the first principal surface side and the second principal surface side;

[0236] a first external electrode disposed on the first end surface; and

[0237] a second external electrode disposed on the second end surface;

[0238] in,

[0239] The laminated body has:

[0240] An effective layer width direction end portion, which is disposed at an end portion in the width direction of the effective layer portion; and

[0241] The effective layer central portion is arranged in the central portion of the effective layer portion,

[0242] The stacked body further has a rare earth segregation region where rare earth elements are segregated.

[0243] In a cross section parallel to the width and height directions,

[0244] With respect to the segregation amount of the rare earth elements in the rare earth segregation region existing at the ends in the width direction of the effective layer, the segregation amount of the rare earth elements in the rare earth segregation region existing in the central portion of the effective layer is in the relationship of effective layer central portion > effective layer width direction ends,

[0245] The dielectric material of the dielectric layer includes a material containing barium, strontium, zirconium, titanium, and hafnium and having a perovskite structure.

[0246] <2>

[0247] according to <1> The multilayer ceramic capacitor, wherein

[0248] A ratio of a segregation amount of the rare earth element in the center portion of the effective layer to that in the widthwise end portions of the effective layer is 2 times or more and 4 times or less.

[0249] <3>

[0250] according to <1> or <2> The multilayer ceramic capacitor, wherein

[0251] The laminate further comprises an aluminum segregation region where aluminum is segregated.

[0252] The aluminum segregation region exists at the widthwise end portions of the effective layer and does not exist in the central portion of the effective layer.

[0253] <4>

[0254] according to <3> The multilayer ceramic capacitor, wherein

[0255] The internal electrode layer has an internal electrode existing region and an internal electrode cutting region.

[0256] The aluminum segregation region exists in the internal electrode dividing region.

[0257] The present invention is not limited to the configuration of the above embodiment, and can be applied with appropriate modifications within the scope of the present invention. Combinations of two or more of the preferred configurations described in the above embodiment also constitute the present invention.

Claims

1. A multilayer ceramic capacitor comprising: A laminate comprising a plurality of laminated dielectric layers and a plurality of laminated internal electrode layers, the laminate comprising a first principal surface and a second principal surface opposing each other in a height direction, a first side surface and a second side surface opposing each other in a width direction perpendicular to the height direction, and a first end surface and a second end surface opposing each other in a length direction perpendicular to the height direction and the width direction, the laminate comprising an effective layer portion and an outer layer portion, the effective layer portion being formed by alternately laminating the dielectric layers and the internal electrode layers, the outer layer portion being arranged so as to sandwich the effective layer portion from the first principal surface side and the second principal surface side; a first external electrode disposed on the first end surface; and a second external electrode disposed on the second end surface; in, The laminated body has: An effective layer width direction end portion, which is disposed at an end portion in the width direction of the effective layer portion; and The effective layer central portion is arranged in the central portion of the effective layer portion, The stacked body further has a rare earth segregation region where rare earth elements are segregated. In a cross section parallel to the width and height directions, With respect to the segregation amount of the rare earth elements in the rare earth segregation region existing at the ends in the width direction of the effective layer, the segregation amount of the rare earth elements in the rare earth segregation region existing in the central portion of the effective layer is in the relationship of effective layer central portion > effective layer width direction ends, The dielectric material of the dielectric layer includes a material containing at least one of calcium, zirconium, and strontium and having a perovskite structure.

2. The multilayer ceramic capacitor according to claim 1, wherein A ratio of a segregation amount of the rare earth element in the center portion of the effective layer to that in the widthwise end portions of the effective layer is 2 times or more and 4 times or less.

3. The multilayer ceramic capacitor according to claim 1 or claim 2, wherein: The laminate further comprises an aluminum segregation region where aluminum is segregated. The aluminum segregation region exists at the widthwise end portions of the effective layer and does not exist in the central portion of the effective layer.

4. The multilayer ceramic capacitor according to claim 3, wherein The internal electrode layer has an internal electrode existing region and an internal electrode cutting region. The aluminum segregation region exists in the internal electrode dividing region.

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