Multilayer ceramic electronic component

Abstract

To provide a multilayer ceramic electronic component capable of suppressing a defect caused by stress concentration.SOLUTION: A multilayer ceramic capacitor 100 comprises: a capacitor region 15 in which an internal electrode 14 and a dielectric layer are laminated; a pair of cover dielectric layers 16 holding a laminate therebetween in a lamination direction; a pair of end faces in which the internal electrodes are alternately exposed; and a pair of side margin regions 18 holding the internal electrodes between side faces. The multilayer ceramic capacitor comprises an external electrode formed on the pair of end faces and consisting of a first metal layer 21a and a second metal layer. The first metal layer covers the pair of cover dielectric layers and a first portion 57a of the pair of side margin regions at the side of the internal electrode, does not cover the cover dielectric layer and a second portion 58a other than the first portion of the side margin region, is in contact with a part of the internal electrode and contains nickel or copper as a main component. The second metal layer covers the first metal layer, covers at least a portion in the second portion at the side of the first metal layer, and contains tin as a main component.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a multilayer ceramic electronic component. [Background technology]

[0002] In a multilayer ceramic electronic component such as a multilayer ceramic capacitor, it is known to provide an uncovered region in which an internal nickel electrode layer is not covered by an external nickel electrode layer, and to provide an external copper electrode layer in the uncovered region (e.g., Patent Document 1). A structure in which the external electrode does not cover the side surface of a side margin portion is also known (e.g., Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-14532 [Patent Document 2] JP 2017-195359 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a multilayer ceramic electronic component is mounted on a mounting board, if stress is concentrated at the ends where the external electrodes contact the element body, problems such as cracks in the element body or peeling of the external electrodes may occur.

[0005] The present invention has been made in consideration of the above-mentioned problems, and has an object to provide a multilayer ceramic electronic component that is capable of suppressing defects caused by stress concentration. [Means for solving the problem]

[0006] The present invention is a multilayer ceramic electronic component comprising: a laminate in which a plurality of internal electrodes and a plurality of dielectric layers are alternately stacked in a first direction; a pair of cover dielectric layers sandwiching the laminate in the first direction; and a pair of end faces in which the stacked internal electrodes are alternately exposed and opposed in a second direction, wherein the plurality of dielectric layers cover an element body having a pair of side margin regions sandwiching the plurality of internal electrodes in a third direction perpendicular to the first direction and the second direction, and each of the pair of end faces, and at least one external electrode covers, at the corresponding end face, a portion of the plurality of internal electrodes and a first portion of the pair of cover dielectric layers and the pair of side margin regions on the side of the plurality of internal electrodes, but does not cover a second portion other than the pair of cover dielectric layers and the pair of side margin regions other than the first portions, and is in contact with a portion of the plurality of internal electrodes, and comprises a first metal layer mainly composed of nickel or copper, and a second metal layer mainly composed of tin that covers the first metal layer and covers at least a portion of the second portion on the side of the first metal layer at the corresponding end face.

[0007] In the above configuration, the present invention is a multilayer ceramic electronic component comprising: a laminate in which a plurality of internal electrodes and a plurality of dielectric layers are alternately stacked in a first direction; a pair of cover dielectric layers sandwiching the laminate in the first direction; and a pair of end faces in which the stacked internal electrodes are alternately exposed and opposed in a second direction, wherein the plurality of dielectric layers cover an element body having a pair of side margin regions sandwiching the plurality of internal electrodes in a third direction perpendicular to the first direction and the second direction, and each of the pair of end faces, wherein at least one external electrode covers, at the corresponding end face, a portion of the plurality of internal electrodes and a first portion of the pair of cover dielectric layers and the pair of side margin regions facing the plurality of internal electrodes, but does not cover a second portion other than the pair of cover dielectric layers and the pair of side margin regions other than the first portions, and comprises a first metal layer in contact with a portion of the plurality of internal electrodes, and a pair of external electrodes covering the first metal layer, covering at least a portion of the second portion on the first metal layer side at the corresponding end face, and having a Young's modulus smaller than that of the first metal layer.

[0008] In the above configuration, the first metal layer may be mainly composed of nickel or copper, and the second metal layer may be mainly composed of tin.

[0009] In the above configuration, the area of ​​the first portion may be set to be 1 / 10 or more and 9 / 10 or less of the area of ​​the second portion.

[0010] In the above configuration, the at least one external electrode may be configured not to cover any surface of the element body other than the corresponding end surface.

[0011] In the above configuration, the second metal layer may be configured to cover up to the edge of the corresponding end face.

[0012] In the above configuration, the second metal layer may be configured not to cover a third portion that is at least a part of a periphery of the corresponding end face.

[0013] In the above configuration, the width of the third portion may be equal to or less than half the width of the second portion.

[0014] In the above configuration, each of the pair of external electrodes may include the first metal layer and the second metal layer. Effect of the Invention

[0015] According to the present invention, it is possible to provide a multilayer ceramic electronic component capable of suppressing defects caused by stress concentration. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along line BB in FIG. [Figure 4] FIG. 4 is a view of the first surface of FIG. 1 seen through the external electrodes. [Diagram 5] FIG. 5 is a view of the second surface of FIG. 1 seen through the external electrodes. [Figure 6] FIG. 6 is a cross-sectional view of the multilayer ceramic capacitor of Comparative Example 1, which corresponds to the cross section AA in FIG. [Figure 7] FIG. 7 is a cross-sectional view of the multilayer ceramic capacitor of Comparative Example 2, which corresponds to the cross section AA in FIG. [Figure 8] 8(a) and 8(b) are diagrams showing the multilayer ceramic capacitors of Comparative Examples 1 and 2 mounted on a mounting board, and FIG. 8(c) is a diagram showing the multilayer ceramic capacitor of the embodiment mounted on a mounting board. [Figure 9] FIG. 9 is a view of the first surface of the multilayer ceramic capacitor of Comparative Example 3, seen through the external electrodes. [Figure 10] FIG. 10 is a flowchart showing an example of a manufacturing process for a multilayer ceramic capacitor. [Figure 11] 11(a) to 11(c) are cross-sectional views showing a method for manufacturing the multilayer ceramic capacitor according to the embodiment. [Figure 12] 12(a) to 12(c) are cross-sectional views showing a method for manufacturing the multilayer ceramic capacitor according to the embodiment. [Figure 13] 13(a) to 13(d) are cross-sectional views showing various examples of external electrodes in the embodiment. [Figure 14] FIG. 14 is a view of the first surface of FIG. 13(b) seen through the external electrodes. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, with reference to the drawings, an embodiment will be described taking a multilayer ceramic capacitor as an example of a multilayer ceramic electronic component.

[0018] (Embodiment) Fig. 1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor 100 according to an embodiment. Fig. 2 is a cross-sectional view taken along line AA in Fig. 1. Fig. 3 is a cross-sectional view taken along line BB in Fig. 1. Fig. 4 is a view of the first surface in Fig. 1 seen through the external electrodes. Fig. 5 is a view of the second surface in Fig. 1 seen through the external electrodes. In Figs. 4 and 5, the regions where metal layers 21a and 21b are provided are indicated by thick dotted lines.

[0019] 1 to 5, the Z direction (first direction) is the stacking direction in which the dielectric layers 14 and the internal electrodes 12a and 12b are stacked, and is the direction in which the fifth surface 55 and the sixth surface 56 of the element body 10 face each other. The X direction (second direction) is the length direction of the element body 10, and is the direction in which the first surface 51 and the second surface 52 of the element body 10 face each other. The Y direction (third direction) is the width direction of the internal electrodes 12a and 12b, and is the direction in which the third surface 53 and the fourth surface 54 of the element body 10 face each other. The X direction, the Y direction, and the Z direction are perpendicular to each other.

[0020] The multilayer ceramic capacitor 100 comprises an element body 10 having a substantially rectangular parallelepiped shape, and external electrodes 20a and 20b.

[0021] The element body 10 has a plurality of dielectric layers 14, a plurality of internal electrodes 12a and 12b, and a cover dielectric layer 16. The plurality of internal electrodes 12a and the plurality of internal electrodes 12b are alternately stacked in the Z direction. One of the plurality of dielectric layers 14 is provided between one of the plurality of internal electrodes 12a and one of the plurality of internal electrodes 12b. The outermost layers in the stacking direction (Z direction) of the laminate 40 in which the dielectric layers 14 and the internal electrodes 12a and 12b are stacked are the internal electrodes 12a and 12b, and a pair of cover dielectric layers 16 are provided to sandwich the laminate 40 in the Z direction of the laminate 40. The region where the internal electrodes 12a and 12b face each other across the dielectric layer 14 is the capacitance region 15. The regions sandwiching the capacitance region 15 in the X direction of the element body 10 in FIG. 2 are a pair of end margin regions 42. The regions sandwiching the capacitance region 15 in the Y direction in FIGS. 3 to 5 are a pair of side margin regions 18.

[0022] The internal electrodes 12a and 12b are alternately exposed on the first surface 51 and the second surface 52. The internal electrode 12a is exposed, but the internal electrode 12b is not exposed, on the first surface 51. The internal electrode 12b is exposed, but the internal electrode 12a is not exposed, on the second surface 52. That is, the internal electrodes 12a and 12b are connected to the first surface 51 and the second surface 52 which are different from each other.

[0023] As shown in Fig. 2, Fig. 4 and Fig. 5, the external electrode 20a (and 20b) (a pair of external electrodes) includes a metal layer 21a (and 21b) (first metal layer) and a metal layer 22a (and 22b) (second metal layer). On the first surface 51 (and the second surface 52), the portion of the cover dielectric layer 16 and the side margin region 18 surrounding the internal electrode 12a (and 12b) on the internal electrode 12a (and 12b) side is a portion 57a ​​(and 57b) (first portion), and the portion of the cover dielectric layer 16 and the side margin region 18 other than the portion 57a ​​(and 57b) is a portion 58a (and 58b) (second portion). The metal layer 21a (and 21b) contacts the internal electrode 12a (and 12b), covers and contacts the portion 57a ​​(and 57b), and does not cover the portion 58a (and 58b).

[0024] Metal layer 22a (and 22b) covers metal layer 21a (and 21b) and covers and contacts portion 58a (and 58b) on first surface 51 (and second surface 52). Metal layer 22a (and 22b) is not provided on third surface 53 and fourth surface 54.

[0025] The size of the multilayer ceramic capacitor 100 is, for example, 0.25 mm in length (length in X direction), 0.125 mm in width (width in Y direction), and 0.125 mm in height (height in Z direction), or 0.4 mm in length, 0.2 mm in width, and 0.2 mm in height, or 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height, or 1.0 mm in length, 0.5 mm in width, and 0.5 mm in height, or 3.2 mm in length, 1.6 mm in width, and 1.6 mm in height, or 4.5 mm in length, 3.2 mm in width, and 2.5 mm in height, but is not limited to these sizes.

[0026] The width of the side margin region 18 in the Y direction is, for example, 10 μm to 30 μm. The length of the end margin region 42 in the X direction is, for example, 10 μm to 50 μm.

[0027] The internal electrodes 12a and 12b are mainly composed of base metals such as nickel (Ni), copper (Cu), and tin (Sn). The internal electrodes 12a and 12b may be made of precious metals such as platinum (Pt), palladium (Pd), silver (Ag), and gold (Au), or alloys containing these metals. The thickness of the internal electrodes 12a and 12b is, for example, 0.1 μm or more and 1 μm or less.

[0028] The dielectric layer 14 has a main phase made of a ceramic material having a perovskite structure represented by the general formula ABO3. 3-αFor example, the ceramic materials include barium titanate (BaTiO3), calcium zirconate (CaZrO3), calcium titanate (CaTiO3), strontium titanate (SrTiO3), magnesium titanate (MgTiO3), and BaTiO3, which forms a perovskite structure. 1-x-y Ca x Sr y Ti 1-z Zr z O3 (0≦x≦1, 0≦y≦1, 0≦z≦1), etc. 1-x-y Ca x Sr y Ti 1-z Zr z O3 is barium strontium titanate, barium calcium titanate, barium zirconate, barium titanate zirconate, calcium titanate zirconate, barium calcium titanate zirconate, etc. For example, the main component ceramic is contained in the dielectric layer 14 at 90 atomic % or more. The thickness of the dielectric layer 14 is, for example, 2 μm or more and 5 μm or less.

[0029] An additive may be added to the dielectric layer 14. Examples of additives to the dielectric layer 14 include oxides of zirconium (Zr), hafnium (Hf), magnesium (Mg), manganese (Mn), molybdenum (Mo), vanadium (V), chromium (Cr), rare earth elements (yttrium (Y), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), and ytterbium (Yb)), oxides containing cobalt (Co), nickel (Ni), lithium (Li), boron (B), sodium (Na), potassium (K), or silicon (Si), or glasses containing cobalt, nickel, lithium, boron, sodium, potassium, or silicon.

[0030] The composition of the main ceramic of the cover dielectric layer 16 may be the same as or different from the main ceramic of the dielectric layer 14. The side margin region 18 may be a side dielectric layer different from the dielectric layer 14. In this case, the composition of the main ceramic of the side dielectric layer may be the same as or different from the main ceramic of the dielectric layer 14.

[0031] The metal layers 21a and 21b of the external electrodes 20a and 20b are mainly composed of a metal such as copper, nickel, aluminum (Al), or zinc (Zn), or an alloy of two or more of these metals (for example, an alloy of copper and nickel), and contain a glass component for densifying the metal layers 21a and 21b. When the metal layers 21a and 21b are fired, they contain a ceramic such as a co-material for controlling the sinterability of the metal layers 21a and 21b. The glass component is an oxide of barium (Ba), strontium (Sr), calcium (Ca), zinc, aluminum, silicon, boron, or the like. The co-material is, for example, a ceramic component mainly composed of the same material as the main component of the dielectric layer 14.

[0032] The metal layers 22a and 22b of the external electrodes 20a and 20b are mainly composed of tin etc. The metal layers 22a and 22b are softer than the metal layers 21a and 21b, that is, the Young's modulus of the metal layers 22a and 22b is smaller than the Young's modulus of the metal layers 21a and 21b.

[0033] 6 is a cross-sectional view of the multilayer ceramic capacitor of Comparative Example 1, corresponding to the cross section AA in FIG. 1. As shown in FIG. 6, in the multilayer ceramic capacitor 110 of Comparative Example 1, the external electrode 20a is provided on the first surface 51 and the ends of the third surface 53, the fourth surface 54, the fifth surface 55, and the sixth surface 56. The external electrode 20b is provided on the second surface 52 and the ends of the third surface 53, the fourth surface 54, the fifth surface 55, and the sixth surface 56. The metal layers 22a and 22b are provided on the metal layers 21a and 21b. The metal layers 22a and 22b are not provided in contact with the first surface 51 and the second surface 52, respectively.

[0034] Fig. 7 is a cross-sectional view of the multilayer ceramic capacitor of Comparative Example 2, corresponding to the cross section AA in Fig. 1. As shown in Fig. 7, in the multilayer ceramic capacitor 112 of Comparative Example 2, the external electrodes 20a and 20b are provided on the first surface 51 and the second surface 52, respectively, and are not provided on the third surface 53, the fourth surface 54, the fifth surface 55, and the sixth surface 56. The metal layers 21a and 21b are provided on the entire surfaces of the first surface 51 and the second surface 52, and the metal layers 22a and 22b are not provided in contact with the first surface 51 and the second surface 52 on the outer sides of the metal layers 21a and 21b.

[0035] 8(a) and 8(b) are diagrams showing the laminated ceramic capacitors of Comparative Examples 1 and 2 mounted on a mounting board, and FIG. 8(c) is a diagram showing the laminated ceramic capacitor of the embodiment mounted on a mounting board. As shown in FIG. 8(a), the laminated ceramic capacitor 110 of Comparative Example 1 is mounted on a land 31 on a mounting board 30. The external electrodes 20a and 20b and the land 31 are joined by a joining material 32 such as solder. When thermal stress caused by the difference in linear expansion coefficient between the mounting board 30 and the element body 10 is applied to the element body 10, the stress is concentrated at a portion 60 at the end of the external electrodes 20a and 20b on the fifth surface 55. This may cause a crack 62 to occur in the element body 10.

[0036] 8(b), in the multilayer ceramic capacitor 112 of Comparative Example 2, the external electrodes 20a and 20b are not provided on the fifth surface 55, so that stress concentration on the fifth surface 55 of the element body 10 can be suppressed. However, points 64 at the ends where the external electrodes 20a and 20b contact the first surface 51 are ends of the metal layers 21a and 21b. Because the metal layers 21a and 21b are made of a hard metal, if stress concentrates on point 64, there is a possibility that the metal layers 21a and 21b will peel off from the element body 10.

[0037] 8(c), in the multilayer ceramic capacitor 100, the metal layers 22a and 22b cover portions 58a and 58b of the first surface 51 and the second surface 52 that are not covered by the metal layers 21a and 21b. The metal layers 22a and 22b are softer than the metal layers 21a and 21b. Therefore, even if stress is concentrated at point 64, the metal layers 22a and 22b are less likely to peel off from the element body 10 than the multilayer ceramic capacitor 112 of Comparative Example 2. Since stress is less likely to concentrate at point 66 at the ends of the metal layers 21a and 21b than at point 64, the metal layers 21a and 21b are less likely to peel off from the element body 10.

[0038] 9 is a view of the first surface of the multilayer ceramic capacitor of Comparative Example 3, seen through the external electrode. The region where the metal layer 21a is provided is indicated by a thick dashed line. As shown in FIG. 9, in the multilayer ceramic capacitor 114 of Comparative Example 3, the metal layer 21a does not cover a region 70 at the end of the internal electrode 12a in the Y direction. As a result, the metal layer 22a contacts the internal electrode 12a in the region 70. When the contact resistance between the metal layer 22a and the internal electrode 12a is high, the contact resistance between the external electrode 20a and the internal electrode 12a also becomes high.

[0039] 4 and 5, in the multilayer ceramic capacitor 100 of the embodiment, the metal layers 21a and 21b are in contact with the internal electrodes 12a and 12b and cover the portions 57a and 57b, thereby making it possible to reduce the contact resistance between the external electrode 20a and the internal electrode 12a.

[0040] (Manufacturing method of multilayer ceramic capacitors) The following describes a method for manufacturing the multilayer ceramic capacitor 100. Fig. 10 is a flow chart showing an example of a manufacturing process for the multilayer ceramic capacitor.

[0041] (Green sheet molding process) First, a green sheet is formed (step S10). In step S10, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer are added to a dielectric material obtained by adding various additive compounds (such as sintering aids) to ceramic powder, and then wet-mixed. The obtained slurry is used to coat a green sheet on a substrate, for example, by a die coater method or a doctor blade method, and then dried. The substrate is, for example, a PET (polyethylene terephthalate) film.

[0042] (Internal electrode printing process) Next, the internal electrodes are printed on the green sheet (step S12). In step S12, a metal conductive paste for forming the internal electrodes containing an organic binder is printed on the green sheet on the base material, for example, by gravure printing. As a result, a plurality of internal electrode patterns corresponding to the internal electrodes 12a and 12b are formed on the green sheet at intervals. Ceramic particles are added to the metal conductive paste as a co-material. The main component of the ceramic particles is not particularly limited, but is preferably the same as the main ceramic component of the dielectric layer 14.

[0043] (Crimping process) Next, the green sheets are stacked and compressed (step S14). In step S14, a laminate sheet is formed by stacking green sheets on which internal electrode patterns that become the internal electrodes 12a and 12b are printed. Green sheets corresponding to the cover dielectric layers 16 are stacked on both end faces in the stacking direction of the laminate sheet. Next, the laminate sheet is pressed to compress the multiple green sheets together. As a compression means, for example, a hydrostatic press is used. Next, the laminate sheet is cut in the stacking direction along predetermined cut lines with a cutting blade to form multiple element bodies 10.

[0044] (Firing process) Next, element body 10 is fired (step S16). In step S16, element body 10 is subjected to a binder removal process in a nitrogen gas atmosphere at 250°C to 500°C, and then fired in a reducing atmosphere at 1300°C to 1400°C for about an hour. This sinters the particles in element body 10 and side dielectric layers 18a and 18b.

[0045] (First metal layer formation process) Next, metal layers 21a and 21b are formed (step S18). Step S18 will be described below with reference to Figs. 11(a) to 12(b).

[0046] 11(a) to 12(c) are cross-sectional views showing a method for manufacturing a multilayer ceramic capacitor according to an embodiment. As shown in FIG. 11(a), a metal sheet 28 is placed on a flat elastic body 24. The metal sheet 28 is placed so as to cover a first surface 51. A tape 26 is attached onto a second surface 52 of the element body 10.

[0047] 11(b), the tape 26 is pressed downward (-X direction) by a pressing device (not shown). As a result, the first surface 51 of the element body 10 is pressed against the surface of the metal sheet 28. At this time, the pressed portion of the metal sheet 28 is recessed by the pressure from the element body 10, and the elastic body 24 below the element body 10 is also recessed. The recessed portion of the metal sheet 28 is pressed against the first surface 51 of the element body 10 by the restoring force from the elastic body 24. As a result, a part of the metal sheet 28 is attached to the first surface 51. At this time, the metal sheet 28 is attached along the corners of the element body 10 at both ends of the first surface 51 in the stacking direction (Z direction). Thereafter, when the pressing force of the element body 10 increases, a shear force is generated between the attached portion of the metal sheet 28 and the other portion, so that the attached portion and the other portion are separated from each other.

[0048] 11(c), the tape 26 is moved upward (in the +X direction) by a pressing device (not shown). This causes the element body 10 to move away from the elastic body 24. At this time, the cut-off portion of the metal sheet 28 is attached to the first surface 51 of the element body 10.

[0049] 11(a) to 11(c), a metal sheet 28 is attached to the second surface 52 of the element body 10. As shown in Fig. 12(a), the metal sheet 28 is attached to the entire surfaces of the first surface 51 and the second surface 52.

[0050] 12(b), barrel polishing is performed. As a result, the outer portion of the metal sheet 28 is polished, and the metal sheet 28 at the peripheral portions 58a and 58b of the first surface 51 and the second surface 52 is removed, forming the metal layers 21a and 21b. At this time, the corners of the element body 10 may be polished and rounded. By selecting the conditions for barrel polishing, the metal sheet 28 can be polished more than the element body 10.

[0051] (Second metal layer formation process) Next, metal layers 22a and 22b are formed (step S20). Step S20 will be described below with reference to FIG.

[0052] As shown in FIG. 12(c), the surfaces of the metal layers 21a and 21b are plated to form the metal layers 22a and 22b on the surfaces of the metal layers 21a and 21b. By appropriately selecting plating conditions, the metal layers 22a and 22b can be formed on the end faces of the metal layers 21a and 21b, so that the metal layers 22a and 22b in contact with the portions 58a and 58b can be formed. By appropriately selecting the plating time, the metal layers 22a and 22b can cover the entire surfaces of the portions 58a and 58b. After forming a thin seed layer on the surfaces of the metal layers 21a and 21b and the portions 58a and 58b by electroless plating or sputtering, the metal layers 22a and 22b may be formed on the surfaces of the seed layers by plating.

[0053] The metal layers 21a and 22a form an external electrode 20a, and the metal layers 21b and 22b form an external electrode 20b.

[0054] (Another example of an external electrode formation process) Prior to the firing step of the element body 10 in step S16 in FIG. 10, paste is applied to the first surface 51 and the second surface 52 as the metal sheet 28 as shown in FIG. 12(a). Then, firing is performed in step S16 in FIG. 10. As shown in FIG. 12(b), the metal sheet 28 shrinks, and portions 58a and 58b that are not covered by the metal layers 21a and 21b are formed on the periphery of the first surface 51 and the second surface 52. Then, as shown in FIG. 12(c), the metal layers 22a and 22b are formed. The external electrodes 20a and 20b may be formed in this manner. The method of forming the external electrodes 20a and 20b is not limited to the above method.

[0055] (Example of external electrodes) 13(a) to 13(d) are cross-sectional views showing various examples of external electrodes in the embodiment. As shown in FIG. 13(a), the metal layer 22a (and 22b) may cover the entire portion 58a (and portion 58b).

[0056] Fig. 14 is a view of the first surface of Fig. 13(b) seen through the external electrode. The areas covered by the metal layers 21a and 22a are indicated by thick dotted lines. As shown in Fig. 13(b) and Fig. 14, the metal layer 22a (and 22b) may cover the inner part of the portion 58a (and portion 58b) and not cover the outer portion 59a. Even in this case, the soft metal layer 22a (and 22b) and the element body 10 contact each other at the end portion 64 of the external electrode 20a (and 20b) where the most stress is concentrated, so that peeling of the metal layer 22a (and 22b) from the element body 10 can be suppressed.

[0057] 13(c), a metal layer 23a may be provided between the metal layer 22a (and 22b) and the metal layer 21a (and 21b). It is sufficient that the outermost metal layers 22a and 22b of the external electrode 20a (and 20b) are softer than the metal layers 21a and 21b in contact with the internal electrodes 12a (and 12b).

[0058] As shown in FIG. 13(d), the metal layer 22a (and 22b) may cover the ends of the fifth surface 55 and the sixth surface 56. In this case, too, the soft metal layer 22a (and 22b) and the element body 10 are in contact at a location 60 of the end of the external electrode 20a (and 20b) where stress is most concentrated, so that peeling of the metal layer 22a (and 22b) from the element body 10 can be suppressed. Also, the occurrence of cracks 62 as shown in FIG. 8(a) can be suppressed. Moreover, because a location 64 of the end of the metal layer 21a (and 21b) is not provided at a corner of the element body 10, stress concentration at the location 64 can be suppressed.

[0059] 13(a) to 13(d), the internal electrode 12a (and 12b) is mainly composed of nickel, for example. The metal layer 21a (and 21b) is mainly composed of nickel or copper, for example. The metal layer 22a (and 22b) is mainly composed of tin, for example. The metal layer 23a is provided as a diffusion barrier layer and is mainly composed of nickel, for example, when the metal layer 21a (and 21b) is mainly composed of copper and the metal layer 22a (and 22b) is mainly composed of tin.

[0060] As described above, in the embodiment, as shown in FIG. 2 and FIG. 4, the metal layer 21a (and 21b) covers the portion 57a ​​(and 57b) but does not cover the portion 58a (and 58b). The metal layer 22a (and 22b) has a Young's modulus smaller than that of the metal layer 21a (and 21b), covers the metal layer 21a (and 21b), and covers at least the portion of the portion 58a (and 58b) on the metal layer 21a (and 21b) side on the first surface 51 (and the second surface 52). This makes it possible to suppress defects such as cracks in the element body 10 or peeling of the external electrodes 20a and 20b, as shown in FIG. 8(c). From the viewpoint of suppressing defects, the Young's modulus of the metal layer 22a (and 22b) is preferably 3 / 4 or less, more preferably 1 / 2 or less, of the Young's modulus of the metal layer 21a (and 21b). The metal layers 21a and 21b are in contact with the entire internal electrodes 12a and 12b, respectively, exposed on the first surface 51 and the second surface 52. This makes it possible to reduce the contact resistance between the external electrodes 20a and 20b and the internal electrodes 12a and 12b.

[0061] Soft metals have low Young's modulus. The Young's modulus of nickel, copper and tin are 204 GPa, 130 GPa and 41 GPa, respectively. Therefore, the metal layers 21a and 21b are mainly composed of nickel or copper, and the metal layers 22a and 22b are mainly composed of tin. The metal layers 21a and 21b may contain co-materials in nickel or copper. The metal layers 22a and 22b may be solders mainly composed of tin, such as tin-silver-copper solder or tin-silver solder. Here, the term "main component" means that other elements or compounds may be intentionally or unintentionally added, and the content is, for example, 50 atomic % or more, 80 atomic % or more, or 90 atomic % or more.

[0062] As shown in Fig. 13(d), the metal layers 22a and 22b of the external electrodes 20a and 20b may cover the ends of the third surface 53, the fourth surface 54, the fifth surface 55 and the sixth surface 56. However, this would increase the size of the multilayer ceramic capacitor. Therefore, as shown in Figs. 13(a) to 13(c), the external electrodes 20a (and 20b) do not cover any surfaces of the element body 10 other than the first surface 51 (and the second surface 52). This allows the multilayer ceramic capacitor to be made smaller.

[0063] As shown in FIG. 13(a), the metal layer 22a (and 22b) may cover the edge of the first surface 51 (and the second surface 52), or as shown in FIG. 13(b), the metal layer 22a (and 22b) may not cover at least a portion 59a (third portion) of the periphery of the first surface 51 (and the second surface 52).

[0064] 4 and 5, if the areas of the portions 58a and 58b are too large, there is a possibility that the internal electrodes 12a and 12b may be exposed from the metal layers 21a and 21b when the alignment between the metal layers 21a and 21b and the internal electrodes 12a and 12b is misaligned. From this viewpoint, the area of ​​the portion 58a is preferably 9 / 10 or less, and more preferably 4 / 5 or less, of the total area of ​​the portions 57a and 58a. The area of ​​the portion 58b is preferably 9 / 10 or less, and more preferably 4 / 5 or less, of the total area of ​​the portions 57b and 58b.

[0065] If the areas of portions 58a and 58b are too small, point 66 (see FIG. 8(c)) at the ends of metal layers 21a and 21b will be close to point 64 at the ends of first surface 51 and second surface 52, causing greater stress concentration at point 66 and possibly causing metal layers 21a and 21b to peel off from element body 10. From this perspective, the area of ​​portion 58a is preferably at least 1 / 10, and more preferably at least 1 / 5, of the total area of ​​portions 57a and 58a. The area of ​​portion 58b is preferably at least 1 / 10, and more preferably at least 1 / 5, of the total area of ​​portions 57b and 58b.

[0066] 4 and 5, the width in the Y direction of the portions 57a and 57b in the side margin region 18 is L1b, the width in the Y direction of the portions 58a and 58b is L2b, and the width in the Y direction of the side margin region 18 is L3b. The width in the Z direction of the portions 57a and 57b in the cover dielectric layer 16 is L1a, the width in the Z direction of the portions 58a and 58b is L2a, and the width in the Z direction of the cover dielectric layer 16 is L3a.

[0067] From the viewpoint of preventing the internal electrodes 12a (and 12b) from being exposed from the metal layers 21a (and 21b), the width L1a (and L1b) is preferably 1 / 10 or more, and more preferably 1 / 5 or more, of the width L3a (and L3b). From the viewpoint of preventing the metal layers 21a (and 21b) from peeling off, the width L1a (and L1b) is preferably 9 / 10 or less, and more preferably 4 / 5 or less, of the width L3a (and L3b).

[0068] 14, if widths L4a and L4b where metal layer 22a is not provided are large, stress is concentrated at the ends of metal layer 21a, and metal layer 21a is likely to peel off from element body 10. From this viewpoint, widths L4a and L4b are preferably equal to or less than ½, and more preferably equal to or less than ⅓ of widths L2a and L2b, respectively. The same is true for second surface 52.

[0069] An example has been described in which both of the pair of external electrodes 20a and 20b include the first metal layers 21a and 21b and the second metal layers 22a and 22b. At least one of the external electrodes 20a and 20b may include the metal layers 21a and 21b and the metal layers 22a and 22b on at least one of the corresponding fifth surface 55 and sixth surface 56.

[0070] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0071] 10 Base 12a, 12b internal electrode 14 Dielectric layer 15 capacity area 16 Cover dielectric layer 18 Side Margin Area 20a, 20b external electrode 21a, 21b, 22a, 22b metal layer 28 Metal Sheet 40 Laminate 42 End Margin Area 51 Page 1 52 2nd page 53 Page 3 54 Page 4 55 Page 5 56 Page 6 57a, 57b, 58a, 58b, 59a parts

Claims

1. an element body including a laminate in which a plurality of internal electrodes and a plurality of dielectric layers are alternately laminated in a first direction, a pair of cover dielectric layers sandwiching the laminate in the first direction, and a pair of end faces at which the plurality of laminated internal electrodes are alternately exposed and which face each other in a second direction; a pair of external electrodes covering the pair of end faces, respectively, wherein at least one of the external electrodes covers, on the corresponding end face, a portion of the plurality of internal electrodes and a first portion of the pair of cover dielectric layers on the side of the plurality of internal electrodes, but does not cover a second portion of the pair of cover dielectric layers other than the first portion, and is in contact with a portion of the plurality of internal electrodes, the first metal layer containing nickel or copper as a main component; and a second metal layer covering the first metal layer and covering at least a portion of the second portion on the corresponding end face that is on the side of the first metal layer, the second metal layer containing tin as a main component; A multilayer ceramic electronic component comprising:

2. an element body including a laminate in which a plurality of internal electrodes and a plurality of dielectric layers are alternately laminated in a first direction, a pair of cover dielectric layers sandwiching the laminate in the first direction, and a pair of end faces at which the plurality of laminated internal electrodes are alternately exposed and which face each other in a second direction; a pair of external electrodes covering the pair of end faces, respectively, wherein at least one of the external electrodes covers, at the corresponding end face, a portion of the plurality of internal electrodes and a first portion of the pair of cover dielectric layers on the side of the plurality of internal electrodes, but does not cover a second portion of the pair of cover dielectric layers other than the first portion, and is in contact with a portion of the plurality of internal electrodes; and a second metal layer covering the first metal layer and covering at least a portion of the second portion on the corresponding end face on the side of the first metal layer, and having a Young's modulus smaller than that of the first metal layer; A multilayer ceramic electronic component comprising:

3. the first metal layer is mainly composed of nickel or copper, 3. The multilayer ceramic electronic component according to claim 2, wherein the second metal layer contains tin as a main component.

4. 4. The multilayer ceramic electronic component according to claim 1, wherein the area of ​​the first portion is 1 / 10 or more and 9 / 10 or less of the area of ​​the second portion.

5. 4. The multilayer ceramic electronic component according to claim 1, wherein the at least one external electrode does not cover any surface of the element body other than the corresponding end face.

6. The multilayer ceramic electronic component according to claim 5 , wherein the second metal layer covers the corresponding end face up to the edge thereof.

7. The multilayer ceramic electronic component according to claim 5 , wherein the second metal layer does not cover a third portion of at least a part of the periphery of the corresponding end face.

8. 8. The multilayer ceramic electronic component according to claim 7, wherein the width of the third portion is equal to or less than half the width of the second portion.

9. The multilayer ceramic electronic component according to claim 1 , wherein each of the pair of external electrodes includes the first metal layer and the second metal layer.

10. A multilayer ceramic electronic component described in any one of claims 1 to 3, wherein at least one of the external electrodes further comprises a third metal layer between the first metal layer and the second metal layer.

11. The element body has a pair of opposing surfaces that face each other in the first direction, The multilayer ceramic electronic component according to claim 1 , wherein the second metal layer covers an end portion of at least one of the pair of opposing surfaces.

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