Multilayer ceramic capacitor and method of manufacturing same

Abstract

The invention provides a multilayer ceramic capacitor and a method of manufacturing the same. The multilayer ceramic capacitor includes: a capacitor body including a dielectric layer and an inner electrode layer; and an external electrode disposed outside the capacitor body, in which the external electrode includes an electrode layer disposed directly on an end portion of the capacitor body in a length direction to be electrically connected to at least one of the inner electrode layers, the electrode layer including a conductive metal and a glass including cobalt (Co), and the amount of cobalt (Co) contained in the glass is 0.13 parts by weight to 0.64 parts by weight based on 100 parts by weight of the conductive metal.

Description

Technical Field

[0001] The present disclosure relates to a multilayer ceramic capacitor and a method for manufacturing the same. Background Art

[0002] As electronic components using ceramic materials, there are capacitors, inductors, piezoelectric elements, varistors, thermistors, etc. Among ceramic electronic components, multilayer ceramic capacitors (MLCCs) can be used in various electronic devices due to advantages such as small size, high capacitance, and easy installation.

[0003] For example, a multilayer ceramic capacitor can be used as a chip capacitor mounted on a board of several electronic products (such as imaging devices (e.g., liquid crystal displays (LCDs), plasma display panels (PDPs), etc.), computers, personal portable terminals, smartphones, etc.) for charging or discharging therefrom.

[0004] Recently, with the miniaturization of electronic products, miniaturization and ultra-high capacitance of multilayer ceramic capacitors have also been required. For this purpose, the following multilayer ceramic capacitors have been manufactured: including a dielectric layer and an internal electrode layer having a relatively reduced thickness to enable a structure in which a relatively large number of dielectric layers and internal electrode layers are stacked. Recently, as miniaturized and ultra-high capacitance multilayer ceramic capacitors have been used in fields requiring high levels of reliability (such as electric vehicles), high reliability is required. Summary of the Invention

[0005] The present disclosure attempts to provide a multilayer ceramic capacitor having excellent moisture-proof reliability and connectivity between an internal electrode and an external electrode.

[0006] The present disclosure provides a method for manufacturing a multilayer ceramic capacitor.

[0007] The present disclosure provides a multilayer ceramic capacitor, including: a capacitor body including a dielectric layer and an internal electrode layer; and an external electrode provided outside the capacitor body, the external electrode including an electrode layer directly provided on an end portion of the capacitor body in a length direction to be electrically connected to at least one internal electrode layer among the internal electrode layers, the electrode layer including a conductive metal and a glass containing cobalt (Co), wherein, based on 100 parts by weight of the conductive metal, the amount of cobalt (Co) contained in the glass is 0.13 parts by weight to 0.64 parts by weight.

[0008] Cobalt (Co) may be contained in a region near the interface, the region near the interface being defined as a region falling within a range of 5% to 15% of the total thickness of the external electrode in the length direction from the interface between the electrode layer of the external electrode and the internal electrode layer toward the electrode layer.

[0009] The glass may further contain iron (Fe).

[0010] Based on 100 parts by weight of the conductive metal, the amount of iron (Fe) contained in the glass may be 0.18 to 0.91 parts by weight.

[0011] Iron (Fe) may be contained in a region near the interface, and the region near the interface is defined as a region that falls within 5% to 15% of the total thickness of the outer electrode in the length direction along the direction toward the electrode layer from the interface between the electrode layer of the outer electrode and the inner electrode layer.

[0012] The glass may further contain lithium (Li), potassium (K), silicon (Si), aluminum (Al), nickel (Ni), silver (Ag), sodium (Na), barium (Ba), calcium (Ca), strontium (Sr), boron (B), zinc (Zn), tin (Sn), copper (Cu), indium (In), titanium (Ti), phosphorus (P), manganese (Mn), germanium (Ge), or a combination thereof.

[0013] In the glass, based on the total amount of the glass, the amount of lithium (Li) contained may be 5 wt% to 20 wt%, the amount of silicon (Si) contained may be 5 wt% to 20 wt%, the amount of aluminum (Al) contained may be 5 wt% to 15 wt%, the amount of nickel (Ni) contained may be 0.01 wt% to 20 wt%, the amount of silver (Ag) contained may be 0.01 wt% to 15 wt%, the amount of sodium (Na) contained may be 0.01 wt% to 25 wt%, the amount of barium (Ba) contained may be 15 wt% to 45 wt%, the amount of boron (B) contained may be 15 wt% to 25 wt%, the amount of zinc (Zn) contained may be 1 wt% to 15 wt%, the amount of tin (Sn) contained may be 0.01 wt% to 15 wt%, the amount of copper (Cu) contained may be 0.01 wt% to 15 wt%, the amount of indium (In) contained may be 0.01 wt% to 15 wt%, the amount of titanium (Ti) contained may be 0.01 wt% to 15 wt%, the amount of phosphorus (P) contained may be 0.01 wt% to 15 wt%, the amount of manganese (Mn) contained may be 0.01 wt% to 15 wt%, and the amount of germanium (Ge) contained may be 0.01 wt% to 15 wt%.

[0014] The amount of potassium (K) contained may be 5 wt% to 20 wt%, and / or the amount of calcium (Ca) contained may be 15 wt% to 45 wt%, and / or the amount of strontium (Sr) contained may be 15 wt% to 45 wt%.

[0015] Based on 100 parts by weight of the conductive metal, the amount of the glass contained in the electrode layer may be 1 to 40 parts by weight.

[0016] The average particle size D50 of the glass may be from 0.1 µm to 5 µm, and D50 refers to the size at 50% of the cumulative size distribution curve.

[0017] The conductive metal may include at least one of copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), and their alloys.

[0018] The conductive metal may include copper (Cu). Based on 100 parts by weight of the conductive metal, the amount of the glass contained in the electrode layer may be from 1 part by weight to 40 parts by weight, and the glass may further include at least one of lithium (Li), silicon (Si), aluminum (Al), nickel (Ni), silver (Ag), sodium (Na), barium (Ba), boron (B), zinc (Zn), tin (Sn), copper (Cu), indium (In), titanium (Ti), phosphorus (P), manganese (Mn), and germanium (Ge).

[0019] The present disclosure provides a method for manufacturing a multilayer ceramic capacitor, the method including: coating a paste of an electrode layer for forming an external electrode onto a surface of a capacitor body including a dielectric layer and an internal electrode layer, wherein the paste includes a conductive metal and a glass composition; and sintering the paste to form the electrode layer of the external electrode, wherein based on 100 parts by weight of the conductive metal, the amount of Co in cobalt oxide (CoO) contained in the glass composition is from 0.13 part by weight to 0.64 part by weight.

[0020] The sintering may be performed at a temperature of 400°C to 850°C.

[0021] The glass composition may further include an iron oxide, and the iron oxide may include FeO, Fe2O3, Fe3O4, or a combination thereof.

[0022] Based on 100 parts by weight of the conductive metal, the amount of Fe in the iron oxide contained in the glass composition may be from 0.18 part by weight to 0.91 part by weight.

[0023] The glass composition may further include at least one of lithium oxide (Li2O), potassium oxide (K2O), silicon dioxide (SiO2), aluminum oxide (Al2O3), nickel oxide (NiO), silver oxide (Ag2O), sodium oxide (Na2O), barium oxide (BaO), calcium oxide (CaO), strontium oxide (SrO), boron trioxide (B2O3), zinc oxide (ZnO), tin oxides (including SnO, SnO2, or a combination thereof), copper oxides (including Cu2O, CuO, or a combination thereof), indium trioxide (In2O3), titanium dioxide (TiO2), phosphorus pentoxide (P2O5), manganese oxides (including MnO, Mn2O, Mn2O3, Mn3O4, or a combination thereof), and germanium dioxide (GeO2).

[0024] In the glass composition, based on the total amount of the glass composition, the amount of Li in the included lithium oxide (Li2O) may be 5 wt% to 20 wt%, the amount of Si in the included silicon dioxide (SiO2) may be 5 wt% to 20 wt%, the amount of Al in the included aluminum oxide (Al2O3) may be 5 wt% to 15 wt%, the amount of Ni in the included nickel oxide (NiO) may be 0.01 wt% to 20 wt%, the amount of Ag in the included silver oxide (Ag2O) may be 0.01 wt% to 15 wt%, the amount of Na in the included sodium oxide (Na2O) may be 0.01 wt% to 25 wt%, the amount of Ba in the included barium oxide (BaO) may be 15 wt% to 45 wt%, the amount of B in the included boron trioxide (B2O3) may be 15 wt% to 25 wt%, the amount of Zn in the included zinc oxide (ZnO) may be 1 wt% to 15 wt%, the amount of Sn in the included tin oxides may be 0.01 wt% to 15 wt%, the amount of Cu in the included copper oxides may be 0.01 wt% to 15 wt%, the amount of In in the included indium trioxide (In2O3) may be 0.01 wt% to 15 wt%, the amount of Ti in the included titanium dioxide (TiO2) may be 0.01 wt% to 15 wt%, the amount of P in the included phosphorus pentoxide (P2O5) may be 0.01 wt% to 15 wt%, the amount of Mn in the included manganese oxides may be 0.01 wt% to 15 wt%, and the amount of Ge in the included germanium dioxide (GeO2) may be 0.01 wt% to 15 wt%.

[0025] The amount of K in the included potassium oxide (K2O) may be 5 wt% to 20 wt%, and / or the amount of Ca in the included calcium oxide (CaO) may be 15 wt% to 45 wt%, and / or the amount of Sr in the included strontium oxide (SrO) may be 15 wt% to 45 wt%.

[0026] In the paste, based on 100 parts by weight of the conductive metal, the amount of the glass composition contained may be 1 part by weight to 40 parts by weight.

[0027] The conductive metal may include at least one of copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), and their alloys.

[0028] The conductive metal may include copper (Cu). In the paste, based on 100 parts by weight of the conductive metal, the amount of the glass composition contained may be 1 part by weight to 40 parts by weight, and the glass composition may further include at least one of lithium oxide (Li2O), silicon dioxide (SiO2), aluminum oxide (Al2O3), nickel oxide (NiO), silver oxide (Ag2O), sodium oxide (Na2O), barium oxide (BaO), boron oxide (B2O3), zinc oxide (ZnO), tin oxides (including SnO, SnO2, or a combination thereof), copper oxides (including Cu2O, CuO, or a combination thereof), indium oxide (In2O3), titanium dioxide (TiO2), phosphorus pentoxide (P2O5), manganese oxides (including MnO, Mn2O, Mn2O3, Mn3O4, or a combination thereof), and germanium dioxide (GeO2).

[0029] The multilayer ceramic capacitor according to the embodiment includes an outer electrode having excellent connectivity with the inner electrode layer, thereby improving moisture-proof reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a perspective view showing a multilayer ceramic capacitor according to an embodiment.

[0031] Figure 2 is along Figure 1 A cross-sectional view of the multilayer ceramic capacitor taken along line I-I' in

[0032] Figure 3 is along Figure 1 A cross-sectional view of the multilayer ceramic capacitor taken along line II-II' in

[0033] Figure 4 is an SEM analysis image showing the inner electrode layer and the outer electrode of the multilayer ceramic capacitor according to Example 1.

[0034] Figure 5 is an SEM analysis image showing the inner electrode layer and the outer electrode of the multilayer ceramic capacitor according to Comparative Example 1.

[0035] Figure 6It is a diagram showing the capacitance of the multilayer ceramic capacitors according to Example 1 and Comparative Example 1. Detailed Description

[0036] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings, in which embodiments of the present disclosure are shown. The drawings and the description are considered to be illustrative rather than restrictive in nature. Throughout the specification, the same reference numerals denote the same elements. In the drawings, some of the constituent elements are enlarged, omitted, or schematically shown, and the dimensions of each constituent element do not fully reflect the actual dimensions.

[0037] The drawings are only intended to facilitate the understanding of the exemplary embodiments disclosed in this specification, and it will be understood that the technical ideas disclosed herein are not limited by the drawings, and include all variations, equivalents, or alternatives within the scope of the ideas and technologies of the present disclosure.

[0038] Although terms such as "first", "second", etc. are used to explain various constituent elements, these constituent elements are not limited by these terms. These terms are only used to distinguish one constituent element from another.

[0039] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it may be directly on the other element, or there may also be an intermediate element. In contrast, when an element is referred to as being "directly on" another element, there is no intermediate element. Additionally, when an element is referred to as being "on" or "above" a reference element, it may be located "above" or "below" the reference element, and does not necessarily mean being located "on" or "above" the reference element in the direction opposite to the direction of gravity.

[0040] Throughout the specification, the term "comprises" or "has" is intended to specify the presence of the stated features, quantities, steps, operations, constituent elements, components, and / or combinations thereof, but does not exclude the presence or addition of one or more other features, quantities, steps, operations, constituent elements, components, and / or combinations thereof. Therefore, unless explicitly described to the contrary, the term "comprises" and variations such as "includes" or "has" will be understood to imply the inclusion of the stated elements but not the exclusion of any other elements.

[0041] In addition, the phrase "in a plane" means observing the target portion from a position above the object (e.g., from the top), and the phrase "in a cross-section" means observing a cross-section of the object obtained by vertically cutting the target portion from the side.

[0042] Throughout the specification, the term "connected" can not only mean that two or more constituent elements are directly connected, but also that two or more constituent elements are indirectly connected through another constituent element, two or more constituent elements are physically and electrically connected, or two or more constituent elements are denoted by different names but are united by position or function.

[0043] Hereinafter, reference will be made to Figures 1 to 3 describe a multilayer ceramic capacitor according to an embodiment.

[0044] Figure 1 is a perspective view showing a multilayer ceramic capacitor according to an embodiment, Figure 2 is along Figure 1 The sectional view of the multilayer ceramic capacitor taken along line I-I' of Figure 3 is along Figure 1 The sectional view of the multilayer ceramic capacitor taken along line II-II' in

[0045] Figures 1 to 3 The L-axis direction, W-axis direction, and T-axis direction shown in are the length direction, width direction, and thickness direction of the capacitor body 110, respectively. Here, the thickness direction (T-axis direction) can be the direction perpendicular to the wide surface (main surface) of the sheet-like component, and can be used, for example, as the same concept as the stacking direction of the stacked dielectric layers 111. The length direction (L-axis direction) can be the direction extending parallel to the wide surface (main surface) of the sheet-like component, and can be substantially perpendicular to the thickness direction (T-axis direction). For example, the length direction (L-axis direction) can be the direction in which the first external electrode 131 and the second external electrode 132 face each other. The width direction (W-axis direction) can be the direction extending parallel to the wide surface (main surface) of the sheet-like component, and can be substantially perpendicular to the thickness direction (T-axis direction) and the length direction (L-axis direction). The length of the sheet-like component in the length direction (L-axis direction) can be greater than the width in the width direction (W-axis direction).

[0046] Refer to Figures 1 to 3 , the multilayer ceramic capacitor 100 according to an embodiment includes a capacitor body 110 and external electrodes 131 and 132 provided outside the capacitor body 110. The external electrodes 131 and 132 can include a first external electrode 131 and a second external electrode 132 provided at opposite ends of the capacitor body 110 in the length direction (L-axis direction).

[0047] Capacitor body For example, the capacitor body 110 can have a substantially hexahedral shape.

[0048] For convenience of describing the embodiments, two surfaces of the capacitor body 110 that are opposite to each other in the thickness direction (T-axis direction) are referred to as a first surface and a second surface, two surfaces that are connected to the first surface and the second surface and are opposite to each other in the length direction (L-axis direction) are referred to as a third surface and a fourth surface, and two surfaces that are connected to the first surface and the second surface, connected to the third surface and the fourth surface, and are opposite to each other in the width direction (W-axis direction) are referred to as a fifth surface and a sixth surface.

[0049] For example, the first surface as the lower surface may be the mounting surface. In addition, the first surface to the sixth surface may be flat, but the embodiments are not limited thereto. For example, the first surface to the sixth surface may be curved surfaces having a convex central portion, and the edges serving as the boundaries of each surface may be rounded.

[0050] The shape and size of the capacitor body 110 and the number of stacked dielectric layers 111 are not limited to the shape and size of the capacitor body and the number of stacked dielectric layers shown in the drawings of the embodiments.

[0051] The capacitor body 110 includes a plurality of dielectric layers 111 and a plurality of inner electrode layers (or “inner electrodes”) 121 and 122. Specifically, the capacitor body 110 includes a plurality of dielectric layers 111 and a first inner electrode 121 and a second inner electrode 122 that are alternately arranged in the thickness direction (T-axis direction) with the dielectric layer 111 interposed therebetween.

[0052] At this time, adjacent dielectric layers 111 of the capacitor body 110 may be integrated to such an extent that it is difficult to inspect the boundary between them without using a scanning electron microscope (SEM).

[0053] The capacitor body 110 may include an effective region. The effective region is a portion that contributes to forming the capacitance of the multilayer ceramic capacitor 100. For example, the effective region may be a region where the first inner electrode 121 and the second inner electrode 122 stacked along the thickness direction (T-axis direction) overlap.

[0054] In addition, the capacitor body 110 may further include a covering region and a side edge region.

[0055] The covering region is an edge portion in the thickness direction and may be respectively located on the upper surface and the lower surface of the effective region in the thickness direction (T-axis direction). The covering region may be a single dielectric layer or two or more dielectric layers respectively stacked on the upper surface and the lower surface of the effective region.

[0056] The side edge regions are edge portions in the width direction and can be respectively located on two side surfaces (the fifth surface and the sixth surface close to the capacitor body 110) of the active region in the width direction (W-axis direction). The side edge regions can be formed by the following method: when applying the conductive paste for the inner electrodes onto the surface of the green dielectric sheet, the conductive paste is applied only to a part of the surface of the green dielectric sheet, and the conductive paste is not applied to both sides of the surface of the green dielectric sheet in the width direction (W-axis direction), and then the green dielectric sheets are stacked and fired.

[0057] The covering region and the side edge regions are used to prevent damage to the first inner electrode 121 and the second inner electrode 122 caused by physical stress and / or chemical stress.

[0058] The dielectric layer 111 includes a barium titanate-based compound as a main component.

[0059] The barium titanate-based compound is a dielectric matrix material, has a high dielectric constant, and contributes to forming the capacitance of the multilayer ceramic capacitor 100.

[0060] The barium titanate-based compound may include, for example, BaTiO3, Ba(Ti, Zr)O3, Ba(Ti, Sn)O3, (Ba, Ca)TiO3, (Ba, Ca)(Ti, Zr)O3, (Ba, Ca)(Ti, Sn)O3, (Ba, Sr)TiO3, (Ba, Sr)(Ti, Zr)O3, (Ba, Sr)(Ti, Sn)O3, or a combination thereof.

[0061] The dielectric layer 111 may further include secondary components. The secondary components may include, for example, manganese (Mn), chromium (Cr), silicon (Si), aluminum (Al), magnesium (Mg), tin (Sn), antimony (Sb), germanium (Ge), gallium (Ga), indium (In), barium (Ba), lanthanum (La), yttrium (Y), actinium (Ac), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), vanadium (V), or a combination thereof.

[0062] The average thickness of the dielectric layer 111 (the average length in the T-axis direction) can be from 2.0 µm to 8.0 µm, for example, from 2.4 µm to 7.8 µm. When the average thickness of the dielectric layer 111 is within the above range, the reliability of the multilayer ceramic capacitor is excellent. The average thickness of the dielectric layer 111 can be obtained by measuring the thickness of the dielectric layer 111 at 10 points spaced at a predetermined interval from a reference point that is the center point of the dielectric layer 111 in the length direction (L-axis direction) or the width direction (W-axis direction) in a scanning electron microscope (SEM) image of a cross-sectional sample and calculating the arithmetic mean. The interval between two adjacent points among the 10 points can be adjusted according to the scale of the SEM image. For example, it can be from 1 µm to 100 µm, from 1 µm to 50 µm, or from 1 µm to 10 µm. At this time, all 10 points must be entirely within the dielectric layer 111. If all 10 points are not entirely within the dielectric layer 111, the position of the reference point can be changed, or the interval between two adjacent points among the 10 points can be adjusted.

[0063] The inner electrode layers 121 and 122 (i.e., the first inner electrode 121 and the second inner electrode 122) are electrodes with different polarities, which are alternately arranged opposite to each other along the T-axis direction, and the dielectric layer 111 is interposed therebetween, and one end of the first inner electrode 121 and one end of the second inner electrode 122 can be exposed through the third surface and the fourth surface of the capacitor body 110, respectively.

[0064] The first inner electrode 121 and the second inner electrode 122 can be electrically insulated from each other through the interposed dielectric layer 111.

[0065] The ends of the first inner electrode 121 and the second inner electrode 122 alternately exposed through the third surface and the fourth surface of the capacitor body 110 can be connected and electrically connected to the first outer electrode 131 and the second outer electrode 132, respectively.

[0066] The first inner electrode 121 and the second inner electrode 122 can include a conductive metal, for example, metals such as Ni, Cu, Ag, Pd, Au or their alloys (such as Ag-Pd alloy).

[0067] In addition, the first inner electrode 121 and the second inner electrode 122 can include dielectric particles having the same composition as the ceramic material included in the dielectric layer 111.

[0068] The first inner electrode 121 and the second inner electrode 122 can be formed using a conductive paste including a conductive metal. The printing method of the conductive paste can be a screen printing method or a gravure printing method.

[0069] The average thickness of the first internal electrode 121 and the second internal electrode 122 may be from 0.1 µm to 2 µm. The average thickness of the first internal electrode 121 and the second internal electrode 122 can be measured by SEM images. Here, since the method for measuring the average thickness of the first internal electrode 121 and the second internal electrode 122 is the same as the method for measuring the average thickness of the dielectric layer 111 described above, its description will be omitted.

[0070] The capacitor body 110 can be formed by firing a stacked structure in which a plurality of dielectric layers 111 and a plurality of internal electrode layers 121 and 122 are stacked.

[0071] External electrode Refer to Figure 2 , different-polarity voltages are applied to the first external electrode 131 and the second external electrode 132, and they can be electrically connected to the exposed portions of the first internal electrode 121 and the second internal electrode 122, respectively.

[0072] According to the above configuration, when a predetermined voltage is applied to the first external electrode 131 and the second external electrode 132, charges accumulate between the opposing first internal electrode 121 and second internal electrode 122. At this time, the capacitance of the multilayer ceramic capacitor 100 is proportional to the overlapping area of the first internal electrode 121 and the second internal electrode 122 stacked along the T-axis direction in the effective region.

[0073] The first external electrode 131 may include a first connection portion provided on the third surface of the capacitor body 110 to connect to the first internal electrode 121, and a first band portion provided at the corner where the third surface of the capacitor body 110 intersects the first surface, the second surface, the fifth surface, and the sixth surface. The second external electrode 132 may include a second connection portion provided on the fourth surface of the capacitor body 110 to connect to the second internal electrode 122, and a second band portion provided at the corner where the fourth surface of the capacitor body 110 intersects the first surface, the second surface, the fifth surface, and the sixth surface.

[0074] The first band portion may extend from the first connection portion to a part of the first surface and a part of the second surface of the capacitor body 110, and may also extend from the first connection portion to a part of the fifth surface and a part of the sixth surface of the capacitor body 110. The second band portion may extend from the second connection portion to a part of the first surface and a part of the second surface of the capacitor body 110, and may also extend from the first connection portion to a part of the fifth surface and a part of the sixth surface of the capacitor body 110. The first band portion and the second band portion can be used to improve the adhesion strength between the first external electrode 131 and the second external electrode 132 and the capacitor body 110, respectively.

[0075] The outer electrodes 131 and 132 include electrode layers 10 and 20 provided at the ends of the capacitor body 110 in the longitudinal direction (L-axis direction) for electrical connection to the inner electrodes 121 and 122. Specifically, the first outer electrode 131 includes a first electrode layer 10 directly provided at one end of the capacitor body 110 in the longitudinal direction (L-axis direction) for electrical connection to the first inner electrode 121. In addition, the second outer electrode 132 includes a second electrode layer 20 directly provided at the other end of the capacitor body 110 in the longitudinal direction (L-axis direction) for electrical connection to the second inner electrode 122.

[0076] The electrode layers 10 and 20 may include a conductive metal and glass.

[0077] The conductive metal may include at least one of copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), and their alloys. Among these materials, the conductive metal may include, for example, copper (Cu) or a copper (Cu) alloy.

[0078] The conductive metal may be in the form of powder. In addition, the conductive metal may have a spherical shape or a flake shape. The size (D50) of the spherical conductive metal may be from 0.1 µm to 5 µm, for example, from 0.5 µm to 3 µm. The major axis size of the flake-shaped conductive metal may be from 1 µm to 20 µm, for example, from 5 µm to 15 µm. The size (D50) of the conductive metal can be obtained by measuring the major axis sizes of at least 100 conductive metal particles in a scanning electron microscope (SEM) image of a cross-sectional sample and creating a size distribution cumulative curve. D50 refers to the size at 50% of the size distribution cumulative curve.

[0079] The glass may include cobalt (Co).

[0080] During the manufacturing process of the capacitor body 110, particularly during the firing process of a dielectric green sheet laminate in which a dielectric layer 111 made of a barium titanate-based compound and inner electrodes 121 and 122 made of nickel (Ni) are alternately laminated, the firing is carried out under relatively mild reducing conditions to prevent deterioration of the characteristics of the dielectric green sheet laminate. In the capacitor body 110 formed after the firing is completed, at the ends of the inner electrodes 121 and 122 made of nickel (Ni), the nickel (Ni) is oxidized to nickel oxide (NiO). According to an embodiment, when a cobalt (Co) component is included in the electrode layers 10 and 20 of the outer electrodes 131 and 132, during the heat treatment of the sintering process when manufacturing the outer electrodes, the reduction behavior of nickel oxide (NiO) at the interface where the outer electrodes 131 and 132 are in contact with the inner electrodes 121 and 122 can be promoted, that is, the reaction of reducing nickel oxide (NiO) can be promoted. Therefore, when the electrode layers 10 and 20 include Cu, a Cu-Ni alloy can be formed and the connectivity between the outer electrode and the inner electrode layer can be improved. In addition, the formation of the Cu-Ni alloy improves the connectivity between the outer electrode and the inner electrode layer, thereby improving the capacitance distribution characteristics and reducing the equivalent series resistance (ESR) value. Therefore, the moisture-proof reliability of the multilayer ceramic capacitor can be improved.

[0081] In the electrode layers 10 and 20, based on 100 parts by weight of the conductive metal, the amount of cobalt (Co) included as a glass component can be 0.13 parts by weight to 0.64 parts by weight, for example, 0.133 parts by weight to 0.636 parts by weight. When the cobalt (Co) included as a glass component in the electrode layers 10 and 20 is within the above content range, during the heat treatment of the firing process, the reduction behavior of nickel oxide (NiO) can be promoted at the interface where the outer electrodes 131 and 132 are in contact with the inner electrodes 121 and 122, which can enhance the formation of the Cu-Ni alloy. Therefore, the connectivity between the outer electrode and the inner electrode layer is improved, thereby ensuring that the multilayer ceramic capacitor has excellent moisture-proof reliability.

[0082] For example, cobalt (Co) may be present in a region within the electrode layers 10 and 20 near the interface between the electrode layers 10 and 20 and the inner electrode layers 121 and 122, that is, in the region R near the interface. Specifically, the region R near the interface can be defined as a region that falls within the range of 5% to 15% of the total thickness of the outer electrodes 131 and 132 in the length direction (L-axis direction) along the direction towards the electrode layers 10 and 20 from the interface between the electrode layers 10 and 20 of the outer electrodes 131 and 132 and the inner electrode layers 121 and 122.

[0083] When cobalt (Co) is mainly included in the region R near the interface, the reduction reaction of nickel oxide (NiO) on the surfaces where the outer electrodes 131 and 132 are in contact with the inner electrode layers 121 and 122 is promoted, thereby promoting the formation of the Cu-Ni alloy. Therefore, the connectivity between the outer electrode and the inner electrode layer can be improved.

[0084] The glass may also include iron (Fe). If the glass includes both cobalt (Co) and iron (Fe), the reduction reaction of nickel oxide (NiO) can be promoted during firing. Therefore, it can contribute to the formation of the Cu-Ni alloy and improve the connectivity between the outer electrode and the inner electrode layer.

[0085] In the electrode layers 10 and 20, based on 100 parts by weight of the conductive metal, the amount of iron (Fe) included as a glass component may be 0.18 parts by weight to 0.91 parts by weight, for example, 0.189 parts by weight to 0.905 parts by weight. When the iron (Fe) included as a glass component in the electrode layers 10 and 20 is within the above content range, it is easy to form the Cu-Ni alloy after sintering and during the formation of the outer electrode, so the connectivity between the outer electrode and the inner electrode layer can be improved.

[0086] For example, iron (Fe) may be present in the regions within the electrode layers 10 and 20 near the interface between the electrode layers 10 and 20 and the inner electrode layers 121 and 122, that is, in the region R near the interface defined above. When iron (Fe) is mainly included in the region R near the interface, the reduction reaction of nickel oxide (NiO) is promoted, thus contributing to the formation of the Cu-Ni alloy. Therefore, the connectivity between the outer electrode and the inner electrode layer can be improved.

[0087] In addition to cobalt (Co) and iron (Fe), the glass may also include lithium (Li), potassium (K), silicon (Si), aluminum (Al), nickel (Ni), silver (Ag), sodium (Na), barium (Ba), calcium (Ca), strontium (Sr), boron (B), zinc (Zn), tin (Sn), copper (Cu), indium (In), titanium (Ti), phosphorus (P), manganese (Mn), germanium (Ge), or a combination thereof.

[0088] Next, the amounts of the respective elements contained in the glass in the electrode layers 10 and 20 will be described. Based on the total amount of the glass, the amount of lithium (Li) contained can be 5 wt% to 20 wt%, for example, 7 wt% to 17 wt%. Based on the total amount of the glass, the amount of potassium (K) contained can be 5 wt% to 20 wt%, for example, 7 wt% to 17 wt%. Based on the total amount of the glass, the amount of silicon (Si) contained can be 5 wt% to 20 wt%, for example, 7 wt% to 17 wt%. Based on the total amount of the glass, the amount of aluminum (Al) contained can be 5 wt% to 15 wt%, for example, 7 wt% to 13 wt%. Based on the total amount of the glass, the amount of nickel (Ni) contained can be 0.01 wt% to 20 wt%, for example, 0.1 wt% to 15 wt%. Based on the total amount of the glass, the amount of silver (Ag) contained can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass, the amount of sodium (Na) contained can be 0.01 wt% to 25 wt%, for example, 0.1 wt% to 20 wt%. Based on the total amount of the glass, the amount of barium (Ba) contained can be 15 wt% to 45 wt%, for example, 20 wt% to 40 wt%. Based on the total amount of the glass, the amount of calcium (Ca) contained can be 15 wt% to 45 wt%, for example, 20 wt% to 40 wt%. Based on the total amount of the glass, the amount of strontium (Sr) contained can be 15 wt% to 45 wt%, for example, 20 wt% to 40 wt%. Based on the total amount of the glass, the amount of boron (B) contained can be 15 wt% to 25 wt%, for example, 17 wt% to 23 wt%. Based on the total amount of the glass, the amount of zinc (Zn) contained can be 1 wt% to 15 wt%, for example, 3 wt% to 13 wt%. Based on the total amount of the glass, the amount of tin (Sn) contained can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass, the amount of copper (Cu) contained can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass, the amount of indium (In) contained can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass, the amount of titanium (Ti) contained can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass, the amount of phosphorus (P) contained can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass, the amount of manganese (Mn) contained can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass, the amount of germanium (Ge) contained can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%.When the above components included as glass components are within the above content ranges, it can contribute to the formation of a Cu-Ni alloy after sintering and during the formation of the outer electrode, thereby improving the connectivity between the outer electrode and the inner electrode layer.

[0089] The above-mentioned glass components included in the electrode layers 10 and 20 can be confirmed by scanning electron microscope (SEM) analysis and electron probe microanalyzer (EPMA) mapping. Even if not described in the present disclosure, other methods and / or other tools understood by those of ordinary skill in the art can be used.

[0090] The SEM analysis can be carried out by the following method. After horizontally placing the multilayer ceramic capacitor 100, the surrounding area of the multilayer ceramic capacitor 100 is fixed with epoxy resin and polished with a polishing machine, so that a cross-sectional sample with a cross-section in the L-T direction can be obtained, which allows the observation of the capacitor body 110 and the outer electrodes 131 and 132. Then the obtained cross-sectional sample can be measured using a scanning electron microscope (SEM). For example, under the conditions of 5 keV and 300 pA, using TESCAN SOLARIS X, SEM analysis is carried out in an area of about 55 µm × 50 µm, so that the inner electrodes 121 and 122 and the outer electrodes 131 and 132 of the multilayer ceramic capacitor 100 can be seen.

[0091] In addition, the electron probe microanalyzer (EPMA) mapping can be carried out by the following method. First, a cross-sectional sample can be obtained from the multilayer ceramic capacitor 100 by the above method. By performing electron probe microanalyzer (EPMA) analysis on the obtained cross-sectional sample, the mapping of each element present in the electrode layer of the outer electrode and the content of each element can be confirmed.

[0092] Through EPMA analysis, it can be seen that cobalt (Co) and iron (Fe) components are observed within the glass matrix. Thus, it can be seen that cobalt (Co) and iron (Fe) exist as glass components in the electrode layers 10 and 20.

[0093] In the electrode layers 10 and 20, based on 100 parts by weight of the conductive metal, the amount of the glass included can be 1 part by weight to 40 parts by weight, for example, 5 parts by weight to 35 parts by weight. When the glass components included are within the above content ranges, a Cu-Ni alloy is formed after sintering, thereby improving the connectivity between the outer electrode and the inner electrode layer.

[0094] The glass may be in particulate form. The size of the glass (specifically, the average particle diameter D50) may be from 0.1 µm to 5 µm, for example, from 0.5 µm to 3 µm. If the size of the glass is within the above range, a Cu-Ni alloy is formed after sintering, thereby improving the connectivity between the outer electrode and the inner electrode layer. The average particle diameter (D50) of the glass can be obtained by measuring the maximum major axis size of at least 100 glass particles in a scanning electron microscope (SEM) image of a cross-sectional sample and creating a cumulative size distribution curve. Even if not described in the present disclosure, other methods and / or other tools understood by those of ordinary skill in the art may be used. D50 refers to the size at 50% of the cumulative size distribution curve.

[0095] The above-mentioned electrode layers 10 and 20 may be sintered metal layers of the outer electrode.

[0096] The outer electrodes 131 and 132 may further include a conductive resin layer (not shown) provided on the electrode layers 10 and 20.

[0097] The conductive resin layer extends to the first and second surfaces and / or the fifth and sixth surfaces of the capacitor body 110, and the length of the region (e.g., the belt portion) where the conductive resin layer extends and is provided on the first and second surfaces and / or the fifth and sixth surfaces of the capacitor body 110 may be greater than the length of the region (e.g., the belt portion) where the electrode layers 10 and 20 extend and are provided on the first and second surfaces and / or the fifth and sixth surfaces of the capacitor body 110. That is, the conductive resin layer is formed on the electrode layers 10 and 20 and may be formed to completely cover the electrode layers 10 and 20.

[0098] The conductive resin layer includes a resin and a conductive metal.

[0099] The resin included in the conductive resin layer may be implemented by a material having adhesiveness and shock-absorbing properties and capable of forming a paste when mixed with conductive metal powder, but is not limited thereto. For example, the resin may include a phenolic resin, an acrylic resin, a silicone resin, an epoxy resin, or a polyimide resin.

[0100] The conductive metal included in the conductive resin layer is used to electrically connect the inner electrode layer 121 or 122 and the electrode layer 10 or 20 to the plating layers 30 or 40 described below.

[0101] The conductive metal included in the conductive resin layer may have a spherical shape, a flake shape, or a combination thereof. That is, the conductive metal may be formed only in the form of flakes, only in the form of spheres, or in a mixed form of flakes and spheres.

[0102] Here, the spherical shape may also include a shape that is not a perfect spherical shape. For example, a shape with a ratio of the length of the major axis to the length of the minor axis (major axis / minor axis) of 1.45 or less. The flake shape refers to a flat and elongated shape and is not particularly limited. However, for example, the ratio of the length of the major axis to the length of the minor axis (major axis / minor axis) may be 1.95 or more.

[0103] The outer electrodes 131 and 132 may also include plating layers 30 and 40 provided to cover the conductive resin layer.

[0104] Specifically, the plating layers 30 and 40 may include a first plating layer 30 provided on the first electrode layer 10 and a second plating layer 40 provided on the second electrode layer 20.

[0105] The plating layers 30 and 40 may include individual nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), or lead (Pb) or their alloys. For example, the plating layer may be a nickel (Ni) plating layer or a tin (Sn) plating layer, may be in a form where a nickel (Ni) plating layer and a tin (Sn) plating layer are stacked in sequence, or may be in a form where a tin (Sn) plating layer, a nickel (Ni) plating layer, and a tin (Sn) plating layer are stacked in sequence. In addition, the plating layer may include multiple nickel (Ni) plating layers and / or multiple tin (Sn) plating layers.

[0106] The plating layer can improve the mountability of the multilayer ceramic capacitor 100 to the substrate, structural reliability, durability against the outside, heat resistance, and equivalent series resistance (ESR).

[0107] Hereinafter, a method for manufacturing the multilayer ceramic capacitor 100 according to an embodiment will be described.

[0108] The multilayer ceramic capacitor 100 according to an embodiment can be manufactured by coating a paste including a conductive metal and a glass composition for forming an electrode layer onto the surface of a capacitor body 110 (including a dielectric layer 111 and inner electrode layers 121 and 122), and sintering the paste for forming the electrode layer to form electrode layers 10 and 20 of the outer electrodes 131 and 132.

[0109] First, a method for manufacturing the capacitor body 110 will be described.

[0110] The capacitor body 110 can be manufactured by preparing a dielectric green sheet using a dielectric slurry and forming a conductive paste layer on the surface of the dielectric green sheet, preparing a dielectric green sheet laminate by stacking the dielectric green sheets having the conductive paste layer formed thereon, and firing the dielectric green sheet laminate.

[0111] The dielectric slurry can be prepared by mixing a barium titanate-based compound as a main component powder and selectively mixing an auxiliary component powder.

[0112] The barium titanate-based compound is the same as described above.

[0113] The sub-component powder may include, for example, manganese (Mn), chromium (Cr), silicon (Si), aluminum (Al), magnesium (Mg), tin (Sn), antimony (Sb), germanium (Ge), gallium (Ga), indium (In), barium (Ba), lanthanum (La), yttrium (Y), actinium (Ac), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), vanadium (V), or a combination thereof, but is not limited thereto. Based on 100 mole parts of the main-component powder of the barium titanate-based compound, the amount of each sub-component powder included may be 0.01 mole part to 5 mole parts.

[0114] The sub-component powder may be used in the form of an oxide or salt compound including various metals, or may be used in the form of a sol dispersed in an organic solvent.

[0115] In addition, the dielectric paste may be prepared by further mixing a solvent and additives such as a dispersant, a binder, a plasticizer, a lubricant, and an antistatic agent.

[0116] The barium titanate-based compound as the main-component powder may be mixed using a wet ball mill or a stirring mill, and optionally the sub-component powder may be mixed. When using zirconia balls in the wet ball mill, a plurality of zirconia balls having a diameter of 0.1 mm to 10 mm may be used for wet mixing for 8 hours to 48 hours (for example, 10 hours to 24 hours).

[0117] The prepared dielectric paste is formed into a dielectric layer after sintering.

[0118] As a method of forming the prepared dielectric paste into a sheet, a tape forming method such as a doctor blade method or a casting roll method may be used, a roll coater using a head discharge method may be used, for example, and a dielectric green sheet may be obtained by subsequently drying the formed body.

[0119] To form a conductive paste layer that becomes an internal electrode after firing, a conductive paste may be prepared by mixing a conductive powder (made of a conductive metal or their alloy), a binder, and a solvent. In addition, if necessary, barium titanate powder may be mixed together as a co-material. During the firing process, the co-material may function to inhibit the sintering of the conductive powder. The conductive paste layer is formed by coating the conductive paste in a predetermined pattern on the surface of the dielectric green sheet using various printing methods such as a screen printing method or a transfer method.

[0120] The conductive powder may include nickel (Ni) or a nickel (Ni) alloy.

[0121] Next, a multilayer dielectric green sheet having an inner electrode pattern is formed by stacking, and then a dielectric green sheet laminate is prepared by pressing the multilayer dielectric green sheet in the stacking direction. At this time, dielectric green sheets without an inner electrode pattern can be stacked such that the dielectric green sheets without an inner electrode pattern are respectively located on the upper surface and the lower surface of the dielectric green sheet laminate in the stacking direction.

[0122] Optionally, a step of cutting the prepared dielectric green sheet laminate into a predetermined size by cutting or the like may be performed.

[0123] Furthermore, if necessary, the dielectric green sheet laminate can be cured and dried to remove a plasticizer or the like, and after curing and drying, the dielectric green sheet laminate can be barrel-polished using a horizontal centrifugal drum machine or the like. During barrel polishing, the dielectric green sheet laminate is placed in a drum container together with a medium and a polishing liquid, and a rotational motion or vibration is applied to the drum container, whereby unnecessary portions such as burrs generated during cutting can be polished. Furthermore, after barrel polishing, the dielectric green sheet laminate can be cleaned with a cleaning solution such as water and dried.

[0124] Subsequently, after the adhesive removal treatment and firing of the dielectric green sheet laminate, a capacitor body can be manufactured.

[0125] The conditions of the adhesive removal treatment can be appropriately adjusted according to the composition of the dielectric layer or the inner electrode layer. For example, the rate of temperature increase during the adhesive removal treatment can be 5°C / hour to 300°C / hour, the treatment temperature can be 180°C to 400°C, and the temperature holding time can be 0.5 hour to 24 hours. The atmosphere during the adhesive removal treatment can be air or a reducing atmosphere.

[0126] The conditions of the firing treatment can be appropriately adjusted according to the main component composition of the dielectric layer or the main component composition of the inner electrode. For example, firing can be performed at a temperature of 1100°C to 1400°C, for example, at a temperature of 1200°C to 1350°C. Furthermore, firing can be performed for 0.5 hour to 8 hours, for example, 1 hour to 3 hours. Furthermore, firing can be performed in a reducing atmosphere, for example, in a humid mixed gas of nitrogen and hydrogen. When the inner electrode includes nickel (Ni) or a nickel (Ni) alloy, the oxygen partial pressure in the firing atmosphere can be 1.0×10 -14 MPa to 1.0×10 -10 MPa.

[0127] After the firing process, annealing may be performed as needed. Annealing is a process of re-oxidizing the dielectric layer, and if firing is performed in a reducing atmosphere, annealing can be carried out. The conditions of the annealing process can also be appropriately adjusted according to the composition of the dielectric layer. For example, the annealing temperature can be from 950 °C to 1150 °C, the time can be from 0 hours to 20 hours, and the rate of temperature increase can be from 50 °C / hour to 500 °C / hour. The annealing atmosphere can be a humidified nitrogen (N2) atmosphere, and the oxygen partial pressure can be 1.0×10 -9 MPa to 1.0×10 -5 MPa.

[0128] In the adhesive removal process, firing process, or annealing process, for example, a wetting agent can be used to humidify nitrogen or a mixed gas. In this case, the wetting agent temperature can be from 5 °C to 75 °C. The adhesive removal process, firing process, and annealing process can be carried out sequentially or independently.

[0129] Optionally, surface treatments such as sandblasting, laser irradiation, barrel polishing, etc. can be performed on the third and fourth surfaces of the manufactured capacitor body 110. By performing such surface treatments, the ends of the first inner electrode and the second inner electrode can be respectively exposed to the third and fourth surfaces, thereby improving the electrical connection between the first outer electrode and the first inner electrode and between the second outer electrode and the second inner electrode, and an alloy portion can be easily formed.

[0130] Hereinafter, a method for manufacturing the outer electrodes 131 and 132 will be described.

[0131] The outer electrodes 131 and 132 can be manufactured by coating a paste for forming an electrode layer on the surface of the manufactured capacitor body 110 and sintering to form the electrode layers 10 and 20.

[0132] The paste for forming an electrode layer may include a conductive metal and a glass composition.

[0133] The conductive metal may include at least one of copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), and their alloys. Among these materials, the conductive metal may include, for example, copper (Cu) or a copper (Cu) alloy.

[0134] The glass composition may include cobalt oxide (CoO).

[0135] In the paste for forming an electrode layer, based on 100 parts by weight of the conductive metal, the amount of Co in the included cobalt oxide (CoO) can be from 0.13 parts by weight to 0.64 parts by weight, for example, from 0.133 parts by weight to 0.636 parts by weight.

[0136] The glass composition may further include iron oxides. The iron oxides may include FeO, Fe2O3, Fe3O4, or a combination thereof.

[0137] In the paste for forming the electrode layer, based on 100 parts by weight of the conductive metal, the amount of Fe in the included iron oxides may be 0.18 parts by weight to 0.91 parts by weight, for example, 0.189 parts by weight to 0.905 parts by weight.

[0138] In addition to cobalt oxide (CoO) and iron oxides, the glass composition may further include at least one of lithium oxide (Li2O), potassium oxide (K2O), silicon dioxide (SiO2), aluminum oxide (Al2O3), nickel oxide (NiO), silver oxide (Ag2O), sodium oxide (Na2O), barium oxide (BaO), calcium oxide (CaO), strontium oxide (SrO), boron oxide (B2O3), zinc oxide (ZnO), tin oxides (including SnO, SnO2, or a combination thereof), copper oxides (including Cu2O, CuO, or a combination thereof), indium oxide (In2O3), titanium dioxide (TiO2), phosphorus pentoxide (P2O5), manganese oxides (including MnO, Mn2O, Mn2O3, Mn3O4, or a combination thereof), and germanium dioxide (GeO2).

[0139] Based on the total amount of the glass composition, the amount of Li in the included lithium oxide (Li2O) can be 5 wt% to 20 wt%, for example, 7 wt% to 17 wt%. Based on the total amount of the glass composition, the amount of K in the included potassium oxide (K2O) can be 5 wt% to 20 wt%, for example, 7 wt% to 17 wt%. Based on the total amount of the glass composition, the amount of Si in the included silicon dioxide (SiO2) can be 5 wt% to 20 wt%, for example, 7 wt% to 17 wt%. Based on the total amount of the glass composition, the amount of Al in the included aluminum oxide (Al2O3) can be 5 wt% to 15 wt%, for example, 7 wt% to 13 wt%. Based on the total amount of the glass composition, the amount of Ni in the included nickel oxide (NiO) can be 0.01 wt% to 20 wt%, for example, 0.1 wt% to 15 wt%. Based on the total amount of the glass composition, the amount of Ag in the included silver oxide (Ag2O) can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass composition, the amount of Na in the included sodium oxide (Na2O) can be 0.01 wt% to 25 wt%, for example, 0.1 wt% to 20 wt%. Based on the total amount of the glass composition, the amount of Ba in the included barium oxide (BaO) can be 15 wt% to 45 wt%, for example, 20 wt% to 40 wt%. Based on the total amount of the glass composition, the amount of Ca in the included calcium oxide (CaO) can be 15 wt% to 45 wt%, for example, 20 wt% to 40 wt%. Based on the total amount of the glass composition, the amount of Sr in the included strontium oxide (SrO) can be 15 wt% to 45 wt%, for example, 20 wt% to 40 wt%. Based on the total amount of the glass composition, the amount of B in the included boron trioxide (B2O3) can be 15 wt% to 25 wt%, for example, 17 wt% to 23 wt%. Based on the total amount of the glass composition, the amount of Zn in the included zinc oxide (ZnO) can be 1 wt% to 15 wt%, for example, 3 wt% to 13 wt%. Based on the total amount of the glass composition, the amount of Sn in the included tin oxide can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass composition, the amount of Cu in the included copper oxide can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass composition, the amount of In in the included indium trioxide (In2O3) can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass composition, the amount of Ti in the included titanium dioxide (TiO2) can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%.Based on the total amount of the glass composition, the amount of P in the contained phosphorus pentoxide (P2O5) can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass composition, the amount of Mn in the contained manganese oxide can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%. Based on the total amount of the glass composition, the amount of Ge in the contained germanium dioxide (GeO2) can be 0.01 wt% to 15 wt%, for example, 0.1 wt% to 10 wt%.

[0140] The glass can be prepared by the following method: mixing the components of the glass composition, heat-treating at a specific temperature or higher, quenching, and then atomizing, or using gas, liquid, spray pyrolysis method.

[0141] In the paste for forming the electrode layer, based on 100 parts by weight of the conductive metal, the amount of the contained glass composition can be 1 part by weight to 40 parts by weight, for example, 5 parts by weight to 35 parts by weight.

[0142] The paste for forming the electrode layer may further include a binder, a solvent, a dispersant, a plasticizer, an oxide powder, etc.

[0143] The binder can be, for example, ethyl cellulose, acrylic acid, butyraldehyde, etc., and the solvent can be, for example, an organic solvent (such as an alcohol (e.g., terpineol, butyl carbitol), methyl ethyl ketone, acetone, toluene, etc.) or an aqueous solvent.

[0144] The method of coating the paste for forming the electrode layer on the outer surface of the capacitor body 110 may include an impregnation method, various printing methods (such as a screen printing method), a coating method using a dispenser, etc., and a spraying method using a sprayer. The paste for forming the electrode layer can be coated on at least one of the third surface and the fourth surface of the capacitor body 110, and optionally coated on a part of the first surface, the second surface, the fifth surface, and / or the sixth surface where the belt portions for forming the first outer electrode and the second outer electrode are to be formed.

[0145] Sintering can be carried out at a temperature of 400°C to 850°C. When sintering is carried out within the above temperature range, nickel oxide (NiO) can be easily reduced to form a Cu-Ni alloy. The formation of the Cu-Ni alloy not only improves the connectivity between the outer electrode and the inner electrode layer, but also improves the capacitance distribution and reduces the equivalent series resistance (ESR).

[0146] Next, the paste for forming the conductive resin layer can be selectively coated on the outer surfaces of the capacitor body 110 where the electrode layers 10 and 20 are formed, and then cured to form the conductive resin layer.

[0147] The paste for forming the conductive resin layer may include a resin and a conductive metal, and optionally includes a non-conductive filler. Since the descriptions of the conductive metal and the resin are the same as those above, the repeated descriptions will be omitted. In addition, the paste for forming the conductive resin layer optionally includes an adhesive, a solvent, a dispersant, a plasticizer, an oxide powder, etc. The adhesive may be, for example, ethyl cellulose, acrylic acid, butyraldehyde, etc., and the solvent may be an organic solvent (such as an alcohol (e.g., terpineol, butyl carbitol), methyl ethyl ketone, acetone, toluene) or an aqueous solvent.

[0148] For example, the conductive resin layer can be formed by dipping the capacitor body 110 in the paste for forming the conductive resin layer and then curing it, or by printing the paste for forming the conductive resin layer on the surface of the capacitor body 110 by a screen printing method or a gravure printing method, or by coating the paste for forming the conductive resin layer on the surface of the capacitor body 110 and then curing it.

[0149] Next, the plating layers 30 and 40 can be formed on the outer side of the conductive resin layer.

[0150] For example, the plating layer can be formed by a plating method, a sputtering method, or an electroplating (electrodeposition) method.

[0151] The above embodiments will be described in more detail by the following examples. However, the following examples are for illustrative purposes only and do not limit the scope of the appended claims.

[0152] (Manufacture of multilayer ceramic capacitor) Examples 1 to 13 and Comparative Examples 1 to 13 A dielectric green sheet laminate (width × length × height = 3.2 mm × 2.5 mm × 2.5 mm) was prepared as follows: A dielectric green sheet was prepared using barium titanate (BaTiO3) as the main component powder, and then a conductive paste layer containing nickel (Ni) was printed on the surface of the dielectric green sheet, and the dielectric green sheets formed with the conductive paste layer were stacked and pressed. Under the condition of 400 °C or lower, the binder removal treatment was carried out in a nitrogen atmosphere, and then the dielectric green sheet laminate was sintered at a sintering temperature of 1300 °C or lower and a hydrogen concentration of 1.0% H2 or lower to manufacture a capacitor body.

[0153] The paste for forming the electrode layer (based on 100 parts by weight of copper (Cu), including 10 parts by weight of a glass composition and 8 parts by weight of an acrylic binder) was coated on the surface of the capacitor body. Here, in the case of Examples 1 to 13 and Comparative Examples 11 to 13, the glass composition was composed of cobalt oxide (CoO) and iron oxide (FeO x)(and is composed of additional components of the composition shown in Table 1 below. In the case of Comparative Examples 1 to 10, the glass composition is composed only of the additional components of the composition having Table 1 (the values therein represent the wt% of elements other than the oxygen element in the additional components).

[0154] Subsequently, as shown in Table 2 below, an electrode layer of the external electrode is formed by sintering at a temperature of 400°C to 850°C. Next, a multilayer ceramic capacitor is manufactured by a process such as plating.

[0155] (Table 1) The unit is wt%.

[0156] (Table 2) Based on 100 parts by weight of Cu, it represents the content of Co in CoO and Fe in FeO x in it.

[0157] Evaluation 1: EPMA analysis Electron probe microanalyzer (EPMA) analysis was performed on the multilayer ceramic capacitors in Examples 1 to 13 and Comparative Examples 1 to 13, and the results are shown in Tables 3 and 4 below.

[0158] The EPMA analysis was performed as follows. After each of the multilayer ceramic capacitors in Examples 1 to 13 and Comparative Examples 1 to 13 was placed horizontally, the surrounding area of the multilayer ceramic capacitor was fixed with epoxy resin and polished with a polishing machine, thereby obtaining a cross-sectional sample having a cross-section in the L-T direction, which allowed observation of the capacitor body and the external electrode. Electron probe microanalyzer (EPMA) analysis was performed on the obtained cross-sectional sample. As a result of the measurement, the mapping and content of each element present in the electrode layer of the external electrode were confirmed.

[0159] (Table 3) Based on 100 parts by weight of Cu, it represents the content of Co and Fe.

[0160] (Table 4) The unit is wt%.

[0161] Referring to Tables 3 and 4 above, it can be seen that in Examples 1 to 13, cobalt (Co) as a glass component contained in the electrode layer of the external electrode is within an appropriate content range.

[0162] Evaluation 2: SEM analysis The multilayer ceramic capacitors in Example 1 and Comparative Example 1 were subjected to scanning electron microscope (SEM) analysis, and the results are shown in Figure 4 and Figure 5 .

[0163] The SEM analysis was performed as follows. After each of the multilayer ceramic capacitors in Example 1 and Comparative Example 1 was placed horizontally, the surrounding area of the multilayer ceramic capacitor was fixed with epoxy resin and polished with a polishing machine to obtain a cross-sectional sample having a cross-section in the L-T direction, which allowed observation of the capacitor body and the external electrodes. Then, the obtained cross-sectional sample could be measured using a scanning electron microscope (SEM). For example, under the conditions of 5 keV and 300 pA, SEM analysis was performed using a TESCAN SOLARIS X in an area of approximately 55 µm × 50 µm, so that the internal electrode layer and the external electrodes of the multilayer ceramic capacitor could be seen.

[0164] Figure 4 is an SEM analysis image showing the internal electrode layer and the external electrodes of the multilayer ceramic capacitor according to Example 1, Figure 5 is an SEM analysis image showing the internal electrode layer and the external electrodes of the multilayer ceramic capacitor according to Comparative Example 1.

[0165] Referring to Figure 4 and Figure 5 , it can be seen that in the case of Example 1 in which the electrode layer of the external electrode includes cobalt (Co) as a glass component, Example 1 includes a structure having excellent connectivity between the internal electrode layer and the external electrodes. On the other hand, in Comparative Example 1 that does not include cobalt (Co), it can be seen that Comparative Example 1 includes a structure having deteriorated connectivity between the internal electrode layer and the external electrodes.

[0166] Evaluation 3: Capacitance, ESR, and moisture resistance reliability A strict evaluation of the capacitance, equivalent series resistance (ESR), and moisture resistance of the multilayer ceramic capacitors in Examples 1 to 13 and Comparative Examples 1 to 13 was measured, and the results are shown in Table 5 below and Figure 6 .

[0167] The capacitance was measured under the conditions of 1 kHz and 0.5 V. Based on the measurement results, for 1000 products, products having a capacitance of 6.8 μF or greater were determined to be of good quality. If the ratio of products of good quality among every 1000 products was less than 70%, it was marked as X. If the ratio of products of good quality among every 1000 products was greater than or equal to 70% and less than 80%, it was marked as △. If the ratio of products of good quality among every 1000 products was greater than or equal to 80% and less than 90%, it was marked as ○. If the ratio of products of good quality among every 1000 products was greater than or equal to 90%, it was marked as ◎.

[0168] The equivalent series resistance (ESR) is measured under the condition of 1 MHz. Based on the measurement results, for 1000 products, products with an ESR of 100 mΩ or less are determined to be of good quality. If the ratio of products of good quality among every 1000 products is less than 97%, it is marked as X. If the ratio of products of good quality among every 1000 products is greater than or equal to 97% and less than 98%, it is marked as △. If the ratio of products of good quality among every 1000 products is greater than or equal to 98% and less than 99%, it is marked as ○. If the ratio of products of good quality among every 1000 products is greater than or equal to 99%, it is marked as ◎.

[0169] The moisture resistance is strictly evaluated using an ESPEC (PR-3J, 8585) device under the conditions of 95°C, 95% relative humidity (R.H.), and 20 hours. During the analysis process, when the IR (insulation resistance) is 10 5 or less, it is defined as a failure, and it is determined based on the mean time to failure (MTTF) for 20000 products. If the mean time to failure is less than or equal to 48 hours, it is marked as X. If the mean time to failure is greater than 48 hours but less than or equal to 216 hours, it is marked as △. If the mean time to failure is greater than 216 hours but less than or equal to 1024 hours, it is marked as ○. If the mean time to failure is greater than 1024 hours, it is marked as ◎.

[0170] (Table 5) The contents of Co and Fe are expressed based on 100 parts by weight of Cu.

[0171] Referring to Table 5, it can be seen that in Examples 1 to 13 in which the electrode layer of the external electrode includes cobalt (Co) within a predetermined content range as a glass component, the capacitance, ESR, and moisture resistance reliability are all excellent. On the contrary, in Comparative Examples 1 to 10 in which cobalt (Co) is not included in the electrode layer of the external electrode and in Comparative Examples 11 to 13 in which cobalt (Co) exceeds the predetermined content range, it can be seen that the capacitance, ESR, and moisture resistance reliability deteriorate.

[0172] Figure 6 is a graph showing the capacitance of the multilayer ceramic capacitor according to Example 1 and Comparative Example 1.

[0173] Referring to Figure 6 , it can be seen that compared with Comparative Example 1 that does not contain cobalt (Co), the capacitance distribution characteristics of Example 1 in which cobalt (Co) is included as a glass component in the electrode layer of the external electrode are improved.

[0174] Although the present disclosure has been described in connection with presently considered to be practical embodiments, it will be understood that the present disclosure is not limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A multilayer ceramic capacitor comprising: a capacitor body including a dielectric layer and an inner electrode layer; as well as An external electrode, disposed outside the capacitor body, The external electrode includes an electrode layer directly disposed on an end portion of the capacitor body in a length direction to be electrically connected to at least one of the internal electrode layers, The electrode layer includes a conductive metal and glass containing Co, Wherein, based on 100 parts by weight of the conductive metal, the amount of Co contained in the glass is 0.13 parts by weight to 0.64 parts by weight.

2. The multilayer ceramic capacitor according to claim 1, wherein Co is included in a region near the interface, which is defined as a region falling within a range of 5% to 15% of a total thickness of the outer electrode in the length direction from an interface between the electrode layer of the outer electrode and the inner electrode layer in a direction toward the electrode layer.

3. The multilayer ceramic capacitor according to claim 1, wherein The glass further contains Fe.

4. The multilayer ceramic capacitor according to claim 3, wherein: The glass may include Fe in an amount of 0.18 to 0.91 parts by weight based on 100 parts by weight of the conductive metal.

5. The multilayer ceramic capacitor according to claim 3, wherein: Fe is contained in a region near the interface, which is defined as a region falling within a range of 5% to 15% of the total thickness of the outer electrode in the length direction from the interface between the electrode layer of the outer electrode and the inner electrode layer in a direction toward the electrode layer.

6. The multilayer ceramic capacitor according to claim 1, wherein The glass also includes Li, K, Si, Al, Ni, Ag, Na, Ba, Ca, Sr, B, Zn, Sn, Cu, In, Ti, P, Mn, Ge or a combination thereof.

7. The multilayer ceramic capacitor according to claim 6, wherein: In the glass, based on the total amount of the glass, The amount of Li contained is 5wt% to 20wt%, The amount of Si contained is 5wt% to 20wt%, The amount of Al contained is 5wt% to 15wt%, The amount of Ni contained is 0.01wt% to 20wt%, The amount of Ag contained is 0.01wt% to 15wt%, The amount of Na contained is 0.01wt% to 25wt%, The amount of Ba contained is 15wt% to 45wt%, The amount of B included is 15wt% to 25wt%, The amount of Zn contained is 1 wt % to 15 wt %, The amount of Sn contained is 0.01wt% to 15wt%, The amount of Cu contained is 0.01wt% to 15wt%, The amount of In contained is 0.01wt% to 15wt%, The amount of Ti contained is 0.01wt% to 15wt%, The amount of P contained is 0.01wt% to 15wt%, The amount of Mn contained is 0.01wt% to 15wt%, And Ge is included in an amount of 0.01 wt % to 15 wt %.

8. The multilayer ceramic capacitor according to claim 7, wherein: K is included in an amount of 5 wt % to 20 wt %, and / or Ca is included in an amount of 15 wt % to 45 wt %, and / or Sr is included in an amount of 15 wt % to 45 wt %.

9. The multilayer ceramic capacitor according to claim 1, wherein: The glass may be included in the electrode layer in an amount of 1 to 40 parts by weight based on 100 parts by weight of the conductive metal.

10. The multilayer ceramic capacitor according to claim 1, wherein The average particle size D50 of the glass is 0.1µm to 5µm, where D50 refers to a size at 50% of a cumulative curve of size distribution.

11. The multilayer ceramic capacitor according to claim 1, wherein The conductive metal includes at least one of Cu, Ni, Ag, Pd, Au, Pt, Sn, W, Ti, Pb and alloys thereof.

12. The multilayer ceramic capacitor according to claim 3, wherein: The conductive metal comprises Cu, The amount of the glass contained in the electrode layer is 1 to 40 parts by weight based on 100 parts by weight of the conductive metal, and The glass also includes at least one of Li, Si, Al, Ni, Ag, Na, Ba, B, Zn, Sn, Cu, In, Ti, P, Mn and Ge.

13. A method of manufacturing a multilayer ceramic capacitor, comprising: applying a paste for forming an electrode layer of an outer electrode to a surface on a capacitor body including a dielectric layer and an inner electrode layer, wherein the paste includes a conductive metal and a glass composition; and sintering the paste to form the electrode layer of the external electrode, Wherein, based on 100 parts by weight of the conductive metal, the glass composition includes Co in CoO in an amount of 0.13 parts by weight to 0.64 parts by weight.

14. The method for manufacturing a multilayer ceramic capacitor according to claim 13, wherein: The sintering is performed at a temperature of 400°C to 850°C.

15. The method for manufacturing a multilayer ceramic capacitor according to claim 13, wherein: The glass composition further comprises iron oxide, And the iron oxide includes FeO, Fe2O3, Fe3O4 or a combination thereof.

16. The method for manufacturing a multilayer ceramic capacitor according to claim 15, wherein: The amount of Fe in the iron oxide included in the glass composition is 0.18 parts by weight to 0.91 parts by weight based on 100 parts by weight of the conductive metal.

17. The method for manufacturing a multilayer ceramic capacitor according to claim 13, wherein: The glass composition also includes at least one of Li2O, K2O, SiO2, Al2O3, NiO, Ag2O, Na2O, BaO, CaO, SrO, B2O3, ZnO, tin oxide, copper oxide, In2O3, TiO2, P2O5, manganese oxide and GeO2, the tin oxide includes SnO, SnO2 or a combination thereof, the copper oxide includes Cu2O, CuO or a combination thereof, and the manganese oxide includes MnO, Mn2O, Mn2O3, Mn3O4 or a combination thereof.

18. The method for manufacturing a multilayer ceramic capacitor according to claim 17, wherein: In the glass composition, based on the total amount of the glass composition, The amount of Li in the Li2O contained is 5wt% to 20wt%, The amount of Si in the SiO2 contained is 5wt% to 20wt%, The amount of Al in the Al2O3 contained is 5wt% to 15wt%, The amount of Ni in the NiO included is 0.01wt% to 20wt%, The amount of Ag in the Ag2O contained is 0.01wt% to 15wt%, The amount of Na in the Na2O contained is 0.01wt% to 25wt%, The amount of Ba in the BaO contained is 15 wt % to 45 wt %, The amount of B in the contained B2O3 is 15wt% to 25wt%, The amount of Zn in the ZnO included is 1 wt % to 15 wt %, The amount of Sn in the tin oxide contained is 0.01wt% to 15wt%, The amount of Cu in the copper oxide contained is 0.01wt% to 15wt%, The amount of In contained in In2O3 is 0.01wt% to 15wt%, The amount of Ti in the TiO2 contained is 0.01wt% to 15wt%, The amount of P in the P2O5 contained is 0.01wt% to 15wt%, The amount of Mn in the manganese oxide contained is 0.01wt% to 15wt%, And the amount of Ge in the contained GeO2 is 0.01wt% to 15wt%.

19. The method for manufacturing a multilayer ceramic capacitor according to claim 18, wherein: K2O is included in an amount of K of 5 wt% to 20 wt%, and / or CaO is included in an amount of Ca of 15 wt% to 45 wt%, and / or SrO is included in an amount of Sr of 15 wt% to 45 wt%.

20. The method for manufacturing a multilayer ceramic capacitor according to claim 13, wherein: In the paste, the glass composition is included in an amount of 1 part by weight to 40 parts by weight based on 100 parts by weight of the conductive metal.

21. The method for manufacturing a multilayer ceramic capacitor according to claim 13, wherein: The conductive metal includes at least one of Cu, Ni, Ag, Pd, Au, Pt, Sn, W, Ti, Pb and alloys thereof.

22. The method for manufacturing a multilayer ceramic capacitor according to claim 16, wherein: The conductive metal comprises Cu, In the paste, the glass composition is included in an amount of 1 to 40 parts by weight based on 100 parts by weight of the conductive metal, and The glass composition also includes at least one of Li2O, SiO2, Al2O3, NiO, Ag2O, Na2O, BaO, B2O3, ZnO, tin oxide, copper oxide, In2O3, TiO2, P2O5, manganese oxide and GeO2, the tin oxide includes SnO, SnO2 or a combination thereof, the copper oxide includes Cu2O, CuO or a combination thereof, and the manganese oxide includes MnO, Mn2O, Mn2O3, Mn3O4 or a combination thereof.

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