Multilayer ceramic capacitor and method for manufacturing the same

Abstract

This invention provides a multilayer ceramic capacitor with improved reliability and structural stability, as well as a method for manufacturing the same. [Solution] A multilayer ceramic capacitor according to an example of the present disclosure has a capacitor body including a plurality of dielectric layers and a plurality of internal electrodes stacked in the third direction, a third and fourth surface facing the second direction and connecting the first and second surfaces, a fifth and sixth surface facing the third direction and connecting the first and second surfaces, an external electrode located outside the capacitor body, and a margin coating layer located on the third and fourth surfaces and containing a barium titanate compound and Nb, wherein the Nb content in the margin coating layer is 0.5 moles to 1 mole per 100 moles of Ti contained in the margin coating layer.

Description

Technical Field

[0001] The disclosure of the present application 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, or thermistors. Among such ceramic electronic components, a multilayer ceramic capacitor (MLCC) can be used in various electronic devices due to its advantages of being small in size, having a guaranteed high capacitance, and being easy to mount.

[0003] For example, a multilayer ceramic capacitor can be used as a chip-shaped capacitor mounted on a substrate of various electronic products such as video devices such as a liquid crystal display (LCD), a plasma display panel (PDP), an organic light-emitting diode (OLED), a computer, a personal mobile terminal, and a smartphone to charge or discharge electricity.

[0004] Recently, due to the miniaturization of electronic products, multilayer ceramic capacitors are also required to be ultra-small and have an ultra-high capacitance. For this purpose, multilayer ceramic capacitors having a structure in which the thicknesses of the dielectric layer and the internal electrode layer are reduced and more dielectric layers and internal electrode layers are laminated have been manufactured. Such ultra-small and ultra-high-capacitance multilayer ceramic capacitors are recently used in fields that require a high level of reliability such as electric vehicles, and thus are in a situation where high stability and high reliability that meet this requirement are required.

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to one aspect of this disclosure, it is possible to provide a multilayer ceramic capacitor with improved reliability and structural stability.

[0006] According to another aspect of this disclosure, a method for manufacturing a multilayer ceramic capacitor with improved reliability and structural stability can be provided.

[0007] However, the problems that the embodiments of the present invention aim to solve are not limited to those described above, and can be broadly extended within the scope of the technical ideas contained in this disclosure. [Means for solving the problem]

[0008] According to one embodiment of the present disclosure, a multilayer ceramic capacitor is provided, comprising a capacitor body having a plurality of dielectric layers and a plurality of internal electrodes stacked in the third direction, having a first surface and a second surface facing each other in a first direction, a third surface and a fourth surface facing each other in a second direction and connecting the first surface and the second surface, and a fifth surface and a sixth surface facing each other in a third direction and connecting the first surface and the second surface; an external electrode located outside the capacitor body; and a margin coating layer located on the third surface and the fourth surface and containing a barium titanate compound and Nb. The Nb content in the margin coating layer is 0.5 moles to 1 mole per 100 moles of Ti contained in the margin coating layer.

[0009] The maximum length of the margin coating layer in the second direction may be greater than 0 μm and less than or equal to 20 μm.

[0010] The Nb contained in the margin coating layer may be derived from a polyvinyl butyral (PVB)-Nb composite.

[0011] The external electrodes are arranged on the first surface and the second surface.

[0012] The margin coating layer may come into contact with the dielectric layer or the internal electrode.

[0013] The margin coating layer may be exposed to the outside.

[0014] In another embodiment of the method for manufacturing a multilayer ceramic capacitor, dielectric green sheets having a conductive paste layer on their surface are stacked in a third direction to form a dielectric green sheet laminate, the dielectric green sheet laminate is cut in the third direction to form a precapacitor body with one end of the conductive paste layer exposed, the precapacitor body is fired to form a capacitor body including a plurality of dielectric layers and a plurality of internal electrodes stacked in the third direction, a margin slurry containing a polyvinyl butyral (PVB)-Nb composite is applied to a margin sheet, the margin sheet and margin slurry are positioned on the capacitor body such that the margin slurry covers one exposed end of the internal electrode, and the margin slurry and margin sheet are fired to form a margin coating layer. The Nb content in the margin coating layer is 0.5 to 1 mole per 100 moles of Ti contained in the margin coating layer.

[0015] The PVB-Nb complex may include a compound in which PVB and Nb are linked through chemical bonds.

[0016] The PVB-Nb composite may include polymers containing repeating units derived from PVB, repeating units derived from polyvinyl alcohol (PVA), and repeating units derived from polyvinyl acetate (PVAc).

[0017] The PVB-Nb complex can be formed by immersing a PVB source and an Nb source in a solvent, mixing them, and drying them.

[0018] The PVB source can include a polymer containing a repeating unit derived from PVB, a repeating unit derived from PVA, and a repeating unit derived from PVAc.

[0019] The polymer of the PVB source can further include a repeating unit containing a carboxyl group at the end.

[0020] The Nb ions contained in the Nb source bind to the carboxyl group to form the PVB-Nb complex.

[0021] The Nb source can include niobium ethoxide.

[0022] The margin slurry can further include a barium titanate-based compound.

[0023] The capacitor body has a first surface and a second surface facing each other in a first direction, a third surface and a fourth surface facing each other in a second direction and connecting the first surface and the second surface, and a fifth surface and a sixth surface facing each other in a third direction and connecting the first surface and the second surface. The margin coating layer is located on the third surface and the fourth surface, and the maximum length of the margin coating layer in the second direction may exceed 0 μm and be 20 μm or less.

Advantages of the Invention

[0024] According to an example of the present disclosure, the density and moisture resistance reliability of the margin coating layer can be improved, and the connectivity between the margin coating layer and the capacitor body can be improved.

[0025] According to an example of the present disclosure, by separately arranging the margin coating layer from the capacitor body, deformation of the internal electrodes can be suppressed, and the reliability and stability of the multilayer ceramic capacitor can be improved.

Brief Description of the Drawings

[0026] [Figure 1]This is a perspective view showing an example of a multilayer ceramic capacitor. [Figure 2] This is a cross-sectional view of a multilayer ceramic capacitor cut along the line I-I' in Figure 1. [Figure 3] This is a cross-sectional view of a multilayer ceramic capacitor cut along the line II-II' in Figure 1. [Figure 4] This is a flowchart illustrating a manufacturing method for a multilayer ceramic capacitor, using one example. [Figure 5] This is a cross-sectional view illustrating an example of a method for manufacturing a multilayer ceramic capacitor. [Figure 6] This is a cross-sectional view illustrating an example of a method for manufacturing a multilayer ceramic capacitor. [Figure 7] This is a cross-sectional view illustrating an example of a method for manufacturing a multilayer ceramic capacitor. [Figure 8] This is a cross-sectional view illustrating an example of a method for manufacturing a multilayer ceramic capacitor. [Figure 9] This is an analysis image of a multilayer ceramic capacitor according to Example 1, obtained using a scanning electron microscopy-microstructure image database and analysis system (SEM-MiDAS). [Figure 10] This is an optical microscope image of a multilayer ceramic capacitor according to Comparative Example 1. [Figure 11] This is an SEM-MiDAS analysis image of a multilayer ceramic capacitor according to Example 1. [Figure 12] This is an SEM-MiDAS analysis image of a multilayer ceramic capacitor according to Comparative Example 1. [Figure 13] This graph shows the results of the moisture resistance reliability evaluation of the multilayer ceramic capacitor according to Example 1. [Figure 14] This graph shows the results of the moisture resistance reliability evaluation of a multilayer ceramic capacitor using Comparative Example 1. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described in detail below with reference to the attached drawings so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. In order to clearly illustrate the present invention, unnecessary parts have been omitted from the drawings, and the same or similar components are denoted by the same reference numerals throughout the specification. Furthermore, some components in the attached drawings are exaggerated, omitted, or shown conceptually, and the size of each component does not fully reflect its actual size.

[0028] The accompanying drawings are provided solely to facilitate understanding of the embodiments disclosed herein, and it should be understood that the accompanying drawings do not limit the technical ideas disclosed herein and include all modifications, equivalents, or substitutions that fall within the concept and scope of the invention.

[0029] Terms including ordinal numbers, such as "first," "second," etc., are used to describe a variety of components, but the components are not limited by such terms. The terms are used solely for the purpose of distinguishing one component from another.

[0030] Furthermore, when a part such as a layer, membrane, region, or plate is said to be "on top of" or "above" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when a part is said to be "directly above" another part, it means that there is no other part in between. Also, being "on top of" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "on top of" or "above" the opposite side of gravity.

[0031] Throughout the specification, terms such as “includes” or “have” are intended to indicate the presence of features, figures, stages, operations, components, parts, or combinations thereof described in the specification, and should be understood not to preemptively exclude the presence or possibility of adding one or more other features, figures, stages, operations, components, parts, or combinations thereof. Therefore, when a part “includes” a component, this means that it may include other components rather than excluding them, unless otherwise stated.

[0032] Furthermore, throughout the specification, "on a plane" refers to the view of the subject from above, and "on a cross-section" refers to the view of a cross-section obtained by cutting the subject perpendicularly, viewed from the side.

[0033] Furthermore, throughout the specification, the term "connected" does not only mean that two or more components are directly connected, but can also mean that two or more components are indirectly connected through other components, that they are not only physically connected but also electrically connected, or that they are a single unit despite being referred to by different names depending on their location or function.

[0034] In the following, a multilayer ceramic capacitor according to an example of this disclosure will be described with reference to Figures 1 to 3.

[0035] Figure 1 is a conceptual perspective view showing an example of a multilayer ceramic capacitor. Figure 2 is a conceptual cross-sectional view of the multilayer ceramic capacitor cut along the line I-I' in Figure 1. Figure 3 is a conceptual cross-sectional view of the multilayer ceramic capacitor cut along the line II-II' in Figure 1.

[0036] Referring to Figures 1 to 3, the multilayer ceramic capacitor 100 may include a capacitor body 110 comprising a dielectric layer 111 and internal electrodes 121, 122, and external electrodes 131, 132 positioned outside the capacitor body 110. The external electrodes 131, 132 may include a first external electrode 131 and a second external electrode 132 positioned at opposite ends of the capacitor body 110 in the longitudinal direction (L-axis direction).

[0037] The L-axis, W-axis, and T-axis shown in Figures 1-3 and 5-8 represent the length, width, and stacking directions of the capacitor body 110, respectively. Here, the stacking direction (T-axis direction) may be perpendicular to the broad surface (main surface) of the sheet-shaped component, and can be used as the same concept as the stacking direction in which the dielectric layer 111 is stacked. The length direction (L-axis direction) extends parallel to the broad surface (main surface) of the sheet-shaped component and may intersect (approximately perpendicular to) the stacking direction (T-axis direction), but for example, it may be the direction in which the first external electrode 131 and the second external electrode 132 are located on both sides. The width direction (W-axis direction) extends parallel to the broad surface (main surface) of the sheet-shaped component and may intersect (approximately perpendicular to) the stacking direction (T-axis direction) and the length direction (L-axis direction), and the length in the length direction (L-axis direction) of the sheet-shaped component may be even greater than the length in the width direction (W-axis direction).

[0038] In one example, the capacitor body 110 may have a substantially hexahedral shape.

[0039] The length direction (L-axis direction) is simply the direction in which the first surface S1 and the second surface S2 face each other; the length in the length direction (L-axis direction) does not necessarily have to be greater than the length in the width direction (W-axis direction).

[0040] For the sake of explanation, in the following, we define the two faces of the capacitor body 110 facing each other in the first direction as the first surface S1 and the second surface S2, the two faces connected to the first surface S1 and the second surface S2 and facing each other in the second direction as the third surface S3 and the fourth surface S4, and the two faces connected to the first surface S1 and the second surface S2 and connected to the third surface S3 and the fourth surface S4 and facing each other in the third direction as the fifth surface S5 and the sixth surface S6.

[0041] In this specification, the first direction and the aforementioned length direction (L-axis direction) may be used interchangeably, the second direction and the aforementioned width direction (W-axis direction) may be used interchangeably, and the third direction and the aforementioned stacking direction (T-axis direction) may be used interchangeably.

[0042] The first and second directions intersect and, for example, may be perpendicular to each other. The second and third directions intersect and, for example, may be perpendicular to each other. The third direction intersects with both the first and second directions and, for example, may be perpendicular to each other.

[0043] The sixth surface S6, which is the lower surface of the capacitor body 110, may be the surface facing the mounting direction of the multilayer ceramic capacitor 100. At least one of the first to sixth surfaces S1 to S6 may be flat. Alternatively, at least one of the first to sixth surfaces S1 to S6 may be a curved surface with a convex center, and the corners that form the boundaries of each surface may be rounded.

[0044] The shape, dimensions, and number of dielectric layers 111 of the capacitor body 110 are not limited to those shown in the drawings of this disclosure.

[0045] The capacitor body 110 may include a dielectric layer 111 and internal electrode layers 121, 122. The capacitor body 110 may include multiple dielectric layers 111.

[0046] The capacitor body 110 may include a plurality of dielectric layers 111, and first internal electrodes 121 and second internal electrodes 122 that are alternately arranged in the stacking direction (T-axis direction) with the dielectric layers 111 in between.

[0047] The boundaries between adjacent dielectric layers 111 can become so integrated that they are difficult to confirm without using a scanning electron microscope (SEM).

[0048] The capacitor body 110 may include an active region. The active region may be a part that contributes to the capacitance formation of the multilayer ceramic capacitor 100. For example, the active region may be an overlapping region of the first internal electrode 121 or the second internal electrode 122 stacked along the stacking direction (T-axis direction).

[0049] The capacitor body 110 may further include a cover area.

[0050] The cover region is a stacking direction margin and is arranged adjacent to the first and second surfaces of the active region in the stacking direction (T-axis direction). For example, a single dielectric layer 111 or two or more dielectric layers 111 are stacked on the upper and lower surfaces of the active region, respectively, to provide the cover region.

[0051] The capacitor body 110 does not necessarily have to include a separate widthwise (W-axis direction) margin portion. For example, one end of the internal electrodes 121 and 122 in the widthwise (W-axis direction) direction is exposed on the third surface S3 and the fourth surface S4 of the capacitor body 110. The exposed end is covered by margin coating layers 141 and 142, which will be described in detail below.

[0052] For example, damage to the first internal electrode 121 and the second internal electrode 122 due to physical or chemical stress can be prevented through the cover region and the margin coating layers 141 and 142.

[0053] The dielectric layer 111 may contain a barium titanate-based compound as its main component. For example, the dielectric properties of the multilayer ceramic capacitor 100 can be ensured by using the barium titanate-based compound as the dielectric base material.

[0054] The aforementioned barium titanate-based compounds may include BaTiO3, BaZrO3, BaSnO3, CaTiO3, CaZrO3, CaSnO3, SrTiO3, SrZrO3, SrSnO3, and the like. These can be used individually or in combination of two or more.

[0055] The dielectric layer 111 may further contain minor components.

[0056] The aforementioned minor components may include 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), 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), and others. These can be used individually or in combination of two or more.

[0057] For example, the average thickness (average length in the T-axis direction) of the dielectric layer 111 may be approximately 1.0 μm to 8.0 μm. For another example, the average thickness (average length in the T-axis direction) of the dielectric layer 111 may be 2 μm to 6 μm. Within this range, the reliability of the multilayer ceramic capacitor 100 can be further improved.

[0058] For example, the average thickness of the dielectric layer 111 can be determined by the arithmetic mean of the dielectric layer 111 thickness measured at 10 points separated by a predetermined interval from the reference point, using an SEM analysis image of a cross-section (LT cross-section) obtained by cutting the multilayer ceramic capacitor 100 perpendicular to the width direction (W-axis direction) from the center in the width direction (W-axis direction) in the length direction (L-axis direction) and the stacking direction (T-axis direction). The interval of the 10 points can be adjusted by the scale of the SEM analysis image, for example, between 1 μm and 100 μm, between 1 μm and 50 μm, or between 1 μm and 10 μm. In this case, all 10 points must be located within the dielectric layer 111. If all 10 points are not located within the dielectric layer 111, the position of the reference point can be changed or the interval between the 10 points can be adjusted.

[0059] The first internal electrode 121 and the second internal electrode 122 of the internal electrodes 121 and 122 can have different polarities. For example, the first internal electrode 121 and the second internal electrode 122 can be arranged alternately so as to face each other along the stacking direction (T-axis direction) with the dielectric layer 111 in between. For example, one end of the first internal electrode 121 in the longitudinal direction (L-axis direction) is exposed through the first surface S1 of the capacitor body 110, and one end of the second internal electrode 122 in the longitudinal direction (L-axis direction) is exposed through the second surface S2 of the capacitor body 110.

[0060] The first internal electrode 121 and the second internal electrode 122 are electrically insulated by a dielectric layer 111 placed between them.

[0061] The end of the first internal electrode 121 exposed through the first surface S1 of the capacitor body 110 can be electrically connected to the first external electrode 131. For example, the end of the second internal electrode 122 exposed through the second surface S2 of the capacitor body 110 can be electrically connected to the second external electrode 132.

[0062] The first internal electrode 121 and the second internal electrode 122 may each include a conductive metal. For example, the conductive metal may include metals such as Ni, Cu, Ag, Pd, Au, or alloys thereof (e.g., Ag-Pd alloy).

[0063] The first internal electrode 121 and the second internal electrode 122 may contain dielectric particles of the same composition as the ceramic material contained in the dielectric layer 111.

[0064] The first internal electrode 121 and the second internal electrode 122 can be formed using a conductive paste containing a conductive metal. For example, the conductive paste can be printed by screen printing or gravure printing.

[0065] For example, the average thickness of the first internal electrode 121 and the second internal electrode 122 may be 0.1 μm to 2 μm. Within this range, the resistance can be further reduced while achieving miniaturization and thinning of the multilayer ceramic capacitor 100.

[0066] The average thickness of the first internal electrode 121 and the second internal electrode 122 can be measured by SEM analysis. This SEM analysis may be substantially the same as the method for measuring the average thickness of the dielectric layer 111 described above.

[0067] The capacitor body 110 can be formed by firing a laminate in which multiple dielectric layers 111 and internal electrode layers 121 and 122 are stacked.

[0068] Referring to Figure 2, the first external electrode 131 and the second external electrode 132 can have different polarities.

[0069] The first external electrode 131 can be electrically connected to the portion of the first internal electrode 121 that is exposed. For example, the second external electrode 132 can be electrically connected to the portion of the second internal electrode 122 that is exposed.

[0070] When a predetermined voltage is applied to the first external electrode 131 and the second external electrode 132, charge is accumulated between the opposing first internal electrode 121 and the second internal electrode 122. The capacitance of the multilayer ceramic capacitor 100 may be proportional to the area overlapping on the plane of the first internal electrode 121 and the second internal electrode 122, which overlap each other in the stacking direction (T-axis direction) in the active region.

[0071] The first external electrode 131 and the second external electrode 132 may include first and second connection portions (not shown) which are arranged on the first surface S1 and the second surface S2 of the capacitor body 110, respectively, and connected to the first internal electrode 121 and the second internal electrode 122, respectively. The first external electrode 131 and the second external electrode 132 may each include first and second band portions (not shown) which are arranged at the corners where the first surface S1 and the second surface S2, the third surface S3 and the fourth surface S4, or the fifth surface S5 and the sixth surface S6 of the capacitor body 110 meet.

[0072] The first band portion and the second band portion extend from the first and second connection portions to a portion of the third surface S3 and fourth surface S4 or the fifth surface S5 and sixth surface S6 of the capacitor body 110, respectively. The fixing strength of the first external electrode 131 and the second external electrode 132 can be improved through the first band portion and the second band portion.

[0073] The first external electrode 131 and the second external electrode 132 may each include a sintered metal layer that contacts the capacitor body 110, a conductive resin layer disposed to cover the sintered metal layer, and a plating layer disposed to cover the conductive resin layer.

[0074] The sintered metal layer may include conductive metal and glass.

[0075] The conductive metal may include copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), alloys thereof, or combinations thereof. For example, copper (Cu) may include copper (Cu) alloys. If the conductive metal includes copper, other metals may be included in amounts of 5 moles or less per 100 moles of copper.

[0076] The glass may contain a composition of mixed oxides, and may include, for example, at least one selected from the group consisting of silicon oxide, boron oxide, aluminum oxide, transition metal oxide, alkali metal oxide, and alkaline earth metal oxide.

[0077] Transition metals may include at least one selected from the group consisting of zinc (Zn), titanium (Ti), copper (Cu), vanadium (V), manganese (Mn), iron (Fe), and nickel (Ni). Alkali metals may include at least one selected from the group consisting of lithium (Li), sodium (Na), and potassium (K). Alkaline earth metals may include at least one selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0078] Selectively, the conductive resin layer is formed on the sintered metal layer, for example, in a form that completely covers the sintered metal layer. For example, the first external electrode 131 and the second external electrode 132 do not have to include the sintered metal layer. In this case, the conductive resin layer can be in direct contact with the capacitor body 110.

[0079] The conductive resin layer extends to the third and fourth surfaces S3 and S4 or the fifth and sixth surfaces S5 and S6 of the capacitor body 110, and the length of the region where the conductive resin layer extends to the third and fourth surfaces S3 and S4 or the fifth and sixth surfaces S5 and S6 of the capacitor body 110 (i.e., the band portion) may be greater than the length of the region where the sintered metal layer extends to the third and fourth surfaces S3 and S4 or the fifth and sixth surfaces S5 and S6 of the capacitor body 110 (i.e., the band portion). For example, the conductive resin layer can be formed on the sintered metal layer and can completely cover the sintered metal layer.

[0080] The conductive resin layer comprises a resin and a conductive metal.

[0081] The resin contained in the conductive resin layer is not particularly limited as long as it has bonding and shock-absorbing properties and can be mixed with conductive metal powder to form a paste, and may include, for example, phenolic resin, acrylic resin, silicone resin, epoxy resin, or polyimide resin.

[0082] The conductive metal contained in the conductive resin layer may be spherical, flake-shaped, or a combination thereof. For example, the conductive metal may consist only of flake-shaped metal, only of spherical metal, or a mixture of flake-shaped and spherical metal.

[0083] Here, spherical can include forms that are not perfectly spherical, for example, forms in which the ratio of the length of the major axis to the length of the minor axis (major axis / minor axis) is 1.45 or less. Flake powder means powder having a flat and elongated shape, and is not particularly limited, but 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.

[0084] The first external electrode 131 and the second external electrode 132 may further include a plating layer disposed on the outside of the conductive resin layer.

[0085] The plating layer may include nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), or lead (Pb), either alone or in alloys thereof. For example, the plating layer may be a nickel (Ni) plating layer or a tin (Sn) plating layer, or it may be a configuration in which a nickel (Ni) plating layer and a tin (Sn) plating layer are sequentially laminated, or it may be a configuration in which a tin (Sn) plating layer, a nickel (Ni) plating layer, and a tin (Sn) plating layer are sequentially laminated. Furthermore, the plating layer may include multiple nickel (Ni) plating layers and / or multiple tin (Sn) plating layers.

[0086] The plating layer improves the mountability, structural reliability, external durability, and heat resistance of the multilayer ceramic capacitor 100 on the substrate, and further reduces the equivalent series resistance (ESR).

[0087] According to one example of this disclosure, the multilayer ceramic capacitor 100 may include margin coating layers 141 and 142 located on a third surface S3 and a fourth surface S4 facing each other in the width direction (W-axis direction), and containing a barium titanate compound and niobium (Nb). The margin coating layers 141 and 142 are provided as width direction (W-axis direction) margin portions of the multilayer ceramic capacitor 100, adjacent to both sides (third surface S3 and fourth surface S4) in the width direction (W-axis direction) of the active region. Through the aforementioned margin coating layers 141 and 142, the density and moisture resistance reliability of the width direction (W-axis direction) margin portion of the multilayer ceramic capacitor 100 can be improved, and the connectivity between the margin coating layers 141 and 142 and the capacitor body 110 can be improved. Furthermore, by arranging the margin coating layers 141 and 142 separately from the capacitor body 110, deformation of the internal electrodes 121 and 122 can be suppressed, improving the reliability and stability of the multilayer ceramic capacitor 100.

[0088] The margin coating layers 141 and 142 may include a first margin coating layer 141 located on the third surface S3 of the capacitor body 110 and a second margin coating layer 142 located on the fourth surface S4.

[0089] For example, margin coating layers 141 and 142 may come into contact with the dielectric layer 111 and the internal electrodes 121 and 122. For instance, the margin coating layers 141 and 142 may come into contact with one end of the dielectric layer 111 and one end of the internal electrodes 121 and 122 exposed on the third surface S3 or fourth surface S4 of the capacitor body 110, thereby electrically connecting them. This protects the side of the active region from external impacts and / or contamination.

[0090] The margin coating layers 141 and 142 are arranged on the capacitor body 110 in the form of a sheet or thin film.

[0091] The barium titanate-based compounds contained in the margin coating layers 141 and 142 may include BaTiO3, CaTiO3, SrTiO3, and the like. These can be used individually or in combination of two or more.

[0092] In one example, the Nb content in the margin coating layers 141 and 142 may be 0.5 to 1 mole per 100 moles of titanium (Ti) contained in the margin coating layers 141 and 142. Within this range, the density of the margin coating layers 141 and 142 can be sufficiently improved, further enhancing the moisture resistance reliability, reliability, and structural stability of the multilayer ceramic capacitor 100.

[0093] To measure the presence of the margin coating layer and the content of its constituent elements, the multilayer ceramic capacitor 100 can be fixed with epoxy resin and polished with a polishing machine so that the cross-section (WT cross-section) is exposed, which is cut perpendicular to the length (L-axis direction) from the center of the multilayer ceramic capacitor 100 in the width direction (W-axis direction) and the stacking direction (T-axis direction). The polishing can be performed so that half of the length in the length direction (L-axis direction) is removed. In the exposed WT cross-section, a rectangular region is set with a width direction (W-axis direction) length of 20 μm and a stacking direction (T-axis direction) length of 200 μm, with a center line passing through the center of the stacking direction (T-axis direction) of the margin coating layers 141 and 142 and extending in the width direction (W-axis direction). The rectangular region can be divided into 10 sub-rectangular regions with a width direction (W-axis direction) length of 20 μm and a stacking direction (T-axis direction) length of 20 μm. The content of elements (such as Nb and Ti), grain size, or number of pores contained in the margin coating layers 141 and 142 can be measured by performing scanning electron microscopy-microstructure image database and analysis system (SEM-MiDAS) or transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) on each of the aforementioned sub-square regions. The content of all Nb elements contained in the 10 sub-square regions can be averaged and evaluated as the Nb content.

[0094] The maximum lengths D1 and D2 in the width direction (W-axis direction) of the margin coating layers 141 and 142 may be greater than 0 μm and 20 μm or less. The maximum length D1 in the width direction (W-axis direction) of the first margin coating layer 141 and the maximum length D2 in the width direction (W-axis direction) of the second margin coating layer 142 may be greater than 0 μm and 20 μm or less, respectively, and may be 5 μm to 20 μm in one example. Within this range, the multilayer ceramic capacitor 100 can be sufficiently miniaturized while protecting the active region from external impact or contamination.

[0095] By performing TEM-EDS analysis or SEM analysis on the WT cross-section of the multilayer ceramic capacitor 100, the lengths D1 and D2 in the width direction (W-axis direction) of the margin coating layers 141 and 142 at the point where their length in the width direction (W-axis direction) is maximum can be measured.

[0096] In one example, the Nb contained in the margin coating layers 141 and 142 may be derived from a polyvinyl butyral (PVB)-Nb composite. This further improves the sinterability and density of the margin coating layers 141 and 142, and further enhances the connectivity / bonding strength with the capacitor body 110. The PVB-Nb composite may contain a polymer. The PVB-Nb composite will be described in detail later in the description of the manufacturing method of the multilayer ceramic capacitor 100.

[0097] The following describes a method for manufacturing a multilayer ceramic capacitor 100 as an example.

[0098] Figure 4 is a flowchart illustrating an example of a multilayer ceramic capacitor manufacturing method. Figures 5 to 8 are cross-sectional views illustrating an example of a multilayer ceramic capacitor manufacturing method. Figures 5 to 8 show cross-sectional views (WT cross-sections) of a dielectric green sheet laminate, a precapacitor, or a multilayer ceramic capacitor, respectively, observed from the same direction as in Figure 3.

[0099] Referring to Figures 4 and 5, a dielectric green sheet laminate 110a can be formed by stacking dielectric green sheets 111a, each having conductive paste layers 121a and 122a on its surface, in the stacking direction (T-axis direction) (for example, in step P1). The dielectric green sheet laminate 110a can refer to a laminated structure in a stage prior to the production of the precapacitor body 110b by cutting, such as by dicing.

[0100] In the manufacturing process of the dielectric green sheet laminate 110a, a dielectric paste that will become the dielectric layer 111 after firing and a conductive paste that will become the internal electrodes 121 and 122 after firing can be prepared.

[0101] Dielectric powder is uniformly mixed and dried through wet mixing or the like, and then heat-treated under predetermined conditions to obtain calcined powder. A dielectric paste can be produced by adding an organic vehicle or an aqueous vehicle to the calcined powder, heating and mixing it.

[0102] The dielectric paste is formed into a sheet using a technique such as the doctor blade method to obtain a dielectric green sheet. For example, the dielectric paste may contain additives selected from various dispersants, plasticizers, dielectrics, minor component compounds, and / or glass.

[0103] Conductive paste for internal electrodes can be prepared by kneading conductive powder, which consists of a conductive metal or an alloy thereof, with a binder or solvent.

[0104] The conductive paste for the internal electrode may contain indium (In).

[0105] The conductive paste for the internal electrode may contain ceramic powder (for example, barium titanate powder) as a co-material. The co-material can suppress the sintering of the conductive powder during the firing process.

[0106] The conductive paste for the internal electrodes can be applied to the surface of the dielectric green sheet 111a in a predetermined pattern using various printing methods such as screen printing or transfer methods. Dielectric green sheet laminates 110a are obtained by stacking multiple layers of dielectric green sheet 111a on which the internal electrode patterns (conductive paste layers 121a, 122a) are formed, and then applying pressure in the stacking direction (T-axis direction). Dielectric green sheet 111a and internal electrode patterns (conductive paste layers 121a, 122a) are stacked such that dielectric green sheet 111a is positioned on the upper and lower surfaces of the dielectric green sheet laminate 110a in the stacking direction (T-axis direction).

[0107] The dielectric green sheet laminate 110a can be solidified and dried to remove plasticizers and other substances as needed, and after solidification and drying, it can be barrel polished using a horizontal centrifugal barrel polishing machine or the like. In the barrel polishing process, the dielectric green sheet laminate 110a is placed in a barrel container along with media and polishing fluid, and rotational motion or vibration is applied to the barrel container to polish away unnecessary parts such as burrs generated during cutting. For example, after barrel polishing, the dielectric green sheet laminate 110a can be washed and dried with a cleaning solution such as water.

[0108] The dielectric green sheet laminate 110a can be subjected to a binder removal treatment. The conditions for the binder removal treatment can be appropriately adjusted depending on the main component composition of the dielectric layer and the main component composition of the internal electrodes. For example, the heating rate during the binder removal treatment may be 5°C / hour to 300°C / hour, the support temperature may be 180°C to 400°C, and the temperature maintenance time may be 0.5 hours to 24 hours. The binder removal atmosphere may be air or a reducing atmosphere.

[0109] Referring to Figures 5 and 6, the dielectric green sheet laminate 110a can be cut in the lamination direction (T-axis direction) to form a precapacitor body 110b in which one end of the conductive paste layers 121b and 122b is exposed (for example, in step P2). In one example, the cutting exposes one end of the conductive paste layers 121b and 122b in the width direction (W-axis direction) to the third surface S3 and the fourth surface S4. For example, the dielectric green sheet laminate 110a can be cut to a predetermined size by dicing or the like.

[0110] Since there is no separate dielectric margin in the width direction (W-axis direction) inside the precapacitor body 110b, and one end of the conductive paste layers 121b and 122b in the width direction (W-axis direction) is exposed to the outside, deformation or damage to the internal electrodes 121 and 122 formed by firing the conductive paste layers 121b and 122b during processes such as pressurization or firing is suppressed. As a result, the structural stability and reliability of the multilayer ceramic capacitor 100 are improved.

[0111] The precapacitor body 110b can be fired to form a capacitor body 110 including multiple dielectric layers 111 and multiple internal electrodes 121, 122 stacked in the stacking direction (T-axis direction) (for example, in step P3).

[0112] The firing conditions can be appropriately adjusted depending on the main component composition of the dielectric layer 111, the main component composition of the internal electrodes 121 and 122, or the composition of the margin slurry. For example, the firing temperature may be 1200°C to 1350°C or 1220°C to 1300°C, and the time may be 0.5 hours to 8 hours, or 1 hour to 3 hours. The firing atmosphere may be a reducing atmosphere, for example, a humidified atmosphere of a mixed gas of nitrogen gas (N2) and hydrogen gas (H2). If the internal electrodes 121 and 122 contain nickel (Ni) or a nickel (Ni) alloy, the oxygen partial pressure in the firing atmosphere should be 1.0 × 10⁻⁶. -14 MPa ~ 1.0 × 10 -10 MPa is also acceptable.

[0113] After the firing process, annealing can be performed as needed. This annealing process is for re-oxidizing the dielectric layer and can be performed when the firing process is carried out in a reducing atmosphere. The conditions for the annealing process can also be appropriately adjusted depending on the main component composition of the dielectric layer. For example, the annealing temperature may be 950°C to 1150°C, the duration may be 0 to 20 hours, and the heating rate may be 50°C / hour to 500°C / hour. The annealing atmosphere may be a humidified nitrogen gas (N2) atmosphere, and the oxygen partial pressure may be 1.0 × 10⁻⁶. -9 MPa ~ 1.0 × 10 -5 MPa is also acceptable.

[0114] For debindering, calcination, or annealing processes, a wetter, for example, can be used to humidify nitrogen gas or a mixed gas, in which case the water temperature may be between 5°C and 75°C. Calcination and annealing processes can be carried out continuously or independently.

[0115] Referring to Figure 7, a margin slurry MS containing a polyvinyl butyral (PVB)-Nb composite can be applied to the margin sheets 141c and 142c (e.g., step P4). Subsequently, the margin sheets 141c and 142c and the margin slurry MS can be placed on the capacitor body 110c such that the margin slurry MS covers one exposed end of the internal electrodes 121c and 122c (e.g., step P5).

[0116] The margin slurry MS and margin sheets 141c and 142c are attached to the third surface S3 and fourth surface S4 of the capacitor body 110c such that the margin slurry MS is in contact with the third surface S3 and fourth surface S4 of the capacitor body 110c that are opposite each other in the width direction (W-axis direction). This protects the active area, including the internal electrodes 121 and 122, from external impact and / or contamination.

[0117] The margin sheets 141c and 142c may contain the aforementioned barium titanate compound. The margin sheets 141c and 142c may also be sheets or layers containing the barium titanate compound.

[0118] The PVB-Nb composite may include compounds in which PVB and Nb are linked through chemical bonds. Chemical bonding of PVB and Nb reduces the average size of the grains of components (Ti, Nb, etc.) contained in the margin coating layers 141 and 142, improving density. This improves the reliability and stability of the margin coating layers 141 and 142, as described later.

[0119] The PVB-Nb composite may include a polymer comprising repeating units derived from PVB, repeating units derived from polyvinyl alcohol (PVA), and repeating units derived from polyvinyl acetate (PVAc). The terminal functional group of the polymer may contain Nb ions (Nb 5+ ) combines with other molecules to achieve stable bonding between polymers.

[0120] The PVB-Nb complex can be formed by immersing a PVB source and an Nb source in a solvent, mixing them, and drying them.

[0121] The solvent may include, for example, organic solvents such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, and toluene, as well as aqueous solvents. As an example, ethanol can be used as the solvent.

[0122] The PVB source may include a polymer containing repeating units derived from PVB, repeating units derived from PVA, and repeating units derived from PVAc.

[0123] The PVB source may further include repeating units having a carboxyl group (-COOH) at its terminus. The carboxyl group of the PVB source polymer and the Nb ion (Nb) of the Nb source 5+ The carboxyl groups bond to form the PVB-Nb composite. Furthermore, the strong hydrogen bonding force of the carboxyl groups improves the interfacial bonding force and moisture resistance reliability of the capacitor body 110 and margin slurry during the formation of the margin coating layers 141 and 142.

[0124] The Nb source may contain niobium ethoxide.

[0125] The Nb ions of the PVB-Nb composite contained in the margin slurry MS can diffuse into the interior of the margin sheets 141c and 142c during the calcination process described later.

[0126] The margin slurry may further contain a barium titanate-based compound.

[0127] The barium titanate-based compound contained in the margin slurry may include BaTiO3, CaTiO3, SrTiO3, and the like. These can be used individually or in combination of two or more.

[0128] In the PVB-Nb composite, the Nb ions replace the Ti ions in the barium titanate compound, improving the electrical properties of the ceramic, such as the dielectric constant, and reducing the size of the crystal grains. This improves the driving stability and reliability of the multilayer ceramic capacitor 100.

[0129] Referring to Figures 7 and 8, margin slurry MS and margin sheets 141c and 142c can be fired to form margin coating layers 141 and 142 (for example, in step P6).

[0130] Through the firing process, the margin slurry MS and margin sheets 141c and 142c are converted into substantially integrated margin coating layers 141 and 142.

[0131] Through the aforementioned firing process, Nb ions from the PVB-Nb composite in the margin slurry MS are diffused within the margin coating layers 141 and 142, and are distributed throughout the margin coating layers 141 and 142, for example.

[0132] During the firing process, the aforementioned PVB-Nb composite reduces the size of the crystal grains of the ceramic material, including barium titanate-based compounds, in the margin slurry MS and margin sheets 141c and 142c, thereby improving the density of the margin coating layers 141 and 142, moisture resistance reliability, and interfacial bonding strength with the capacitor body 110.

[0133] The firing conditions for the margin slurry MS and margin sheets 141c and 142c may be substantially the same as or similar to the firing conditions for the precapacitor body 110b described above.

[0134] In one example, the Nb content in the margin coating layers 141 and 142 may be 0.5 to 1 mole per 100 moles of Ti contained in the margin coating layers 141 and 142. Within this range, the density and adhesion of the margin coating layers 141 and 142 are sufficiently improved during firing, further enhancing the moisture resistance reliability, reliability, and structural stability of the multilayer ceramic capacitor 100.

[0135] Selectively, surface treatments such as sandblasting, laser irradiation, or barrel polishing can be performed on the first surface S1 and the second surface S2 of the obtained capacitor body 110. Through such surface treatments, the ends of the first internal electrode 121 and the second internal electrode 122 are exposed on the outermost surfaces of the first surface S1 and the second surface S2, respectively. This improves the electrical connection between the first external electrode 131 and the first internal electrode 121, and between the second external electrode 132 and the second internal electrode 122, and facilitates the formation of the alloy portion.

[0136] External electrodes 131 and 132 can be formed on one surface (for example, the first surface S1 and the second surface S2) of the manufactured capacitor body 110.

[0137] As an example, a paste for forming a sintered metal layer can be applied to the outer surface of the capacitor body 110 and then sintered to form a sintered metal layer.

[0138] The paste for forming a sintered metal layer may contain the aforementioned conductive metals and glass. Furthermore, the paste for forming a sintered metal layer may selectively contain a binder, solvent, dispersant, plasticizer, oxide powder, etc. The binder may include, for example, ethyl cellulose, acrylic, butyral, and the solvent may include, for example, organic solvents such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, toluene, or aqueous solvents.

[0139] As a method for applying the sintered metal layer forming paste to the outer surface of the capacitor body 110, various printing methods such as dipping and screen printing, application methods using dispensers, and spraying methods using sprays can be used.

[0140] The sintered metal layer forming paste is applied to at least the first surface S1 and the second surface S2 of the capacitor body 110, and is also applied to a portion of the third surface S3, fourth surface S4, fifth surface S5, or sixth surface S6, where the band portions of the first external electrode 131 and the second external electrode 132 are selectively formed.

[0141] Subsequently, the capacitor body 110 coated with the paste for forming the sintered metal layer is dried, and the sintered metal layer can be formed by sintering it at a temperature of 700°C to 1000°C for 0.1 to 3 hours.

[0142] Selectively, a conductive resin layer can be formed on the outer surface of the obtained capacitor body 110 by applying a paste for forming a conductive resin layer and then curing it.

[0143] The paste for forming a conductive resin layer may contain a resin and, selectively, a conductive metal or a non-conductive filler. The descriptions of conductive metals and resins are the same as those given above, so a repetitive explanation will be omitted. The paste for forming a conductive resin layer may also selectively contain a binder, solvent, dispersant, plasticizer, oxide powder, etc. The binder may be, for example, ethyl cellulose, acrylic, butyral, etc., and the solvent may be an organic solvent such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, toluene, or an aqueous solvent.

[0144] As an example, the conductive resin layer can be formed by dipping the capacitor body 110 into a conductive resin layer forming paste and then curing it, or by printing the conductive resin layer forming paste onto the surface of the capacitor body 110 using a screen printing method or gravure printing method, or by applying the conductive resin layer forming paste to the surface of the capacitor body 110 and then curing it.

[0145] A plating layer can be formed on the outside of the conductive resin layer.

[0146] For example, the plating layer can be formed by a plating method, and can also be formed by sputtering or electroplating (electric deposition).

[0147] The following provides specific examples of the present disclosure. The examples described below are for illustrative or illustrative purposes only. [Examples]

[0148] [Example 1] (Manufacturing of PVB-Nb complex) As a PVB source, 10 g of PVB containing a -COOH group at the end was added to 100 mL of ethanol solvent to prepare the solution.

[0149] 0.1 g of niobethoxide was added to the aforementioned solution and mixed to form a mixture.

[0150] The mixture was stirred and dried at 90°C to produce a PVB-Nb composite.

[0151] (Preparation of margin slurry and margin sheet) A margin slurry was prepared by mixing the aforementioned PVB-Nb composite, BaTiO3 powder, and solvent.

[0152] A margin sheet with a thickness of approximately 15 μm (maximum length in the width direction) was prepared using barium titanate powder.

[0153] The margin slurry was applied to one surface of the margin sheet to a thickness of approximately 20 nm (maximum length in the width direction).

[0154] The content of the PVB-Nb composite was adjusted so that the Nb content was 0.5 moles per 100 moles of Ti contained in the margin slurry and margin sheet.

[0155] (Manufacturing of multilayer ceramic capacitors) After manufacturing a dielectric green sheet using barium titanate (BaTiO3) as the main component powder, a conductive paste layer containing Ni was printed onto the surface of the dielectric green sheet. Dielectric green sheet laminates were then manufactured by stacking and pressing the dielectric green sheets with the conductive paste layer on their surfaces in the stacking direction (T-axis direction).

[0156] The dielectric green sheet laminate was cut in the lamination direction (T-axis direction) to form a precapacitor body (width × length × height = 3.2 mm × 2.5 mm × 2.5 mm) in which one end of the conductive paste layer was exposed in the width direction (W-axis direction). The precapacitor body was then fired in a nitrogen atmosphere at a temperature of 400°C or less, at a firing temperature of 1400°C or less, and with a hydrogen concentration of 1.0% H2 or less to produce a capacitor body. The capacitor body had internal electrodes exposed on the third and fourth surfaces facing each other in the width direction (W-axis direction).

[0157] Two bonded portions of the margin slurry and margin sheet were attached to both sides (the third and fourth surfaces) of the capacitor body, respectively, so that the margin slurry was in contact with the third and fourth surfaces of the capacitor body. The margin slurry and margin sheet were fired under the same conditions and method as the firing of the precapacitor body to form a margin coating layer with a thickness of 15 μm (maximum length in the width direction).

[0158] Next, a multilayer ceramic capacitor was manufactured by applying external electrodes, plating, and other processes to the first and second surfaces of the capacitor body.

[0159] [Example 2] A PVB-Nb composite, margin slurry, margin sheet, and multilayer ceramic capacitor were manufactured in the same manner as in Example 1, except that the content of the PVB-Nb composite was adjusted so that the Nb content was 0.75 mol parts per 100 mol parts total Ti contained in the margin slurry and margin sheet.

[0160] [Example 3] A PVB-Nb composite, margin slurry, margin sheet, and multilayer ceramic capacitor were manufactured in the same manner as in Example 1, except that the content of the PVB-Nb composite was adjusted so that the Nb content was 1.0 mol part per 100 mol parts of total Ti contained in the margin slurry and margin sheet.

[0161] [Comparative Example 1] A margin slurry, margin sheet, and multilayer ceramic capacitor were manufactured in the same manner as in Example 1, except that the same amount of PVB (BL-S grade) was used instead of the PVB-Nb composite.

[0162] [Comparative Example 2] A PVB-Nb composite, margin slurry, margin sheet, and multilayer ceramic capacitor were manufactured in the same manner as in Example 1, except that the content of the PVB-Nb composite was adjusted so that the Nb content was 0.25 mol parts per 100 mol parts total Ti contained in the margin slurry and margin sheet.

[0163] [Comparative Example 3] A PVB-Nb composite, margin slurry, margin sheet, and multilayer ceramic capacitor were manufactured in the same manner as in Example 1, except that the content of the PVB-Nb composite was adjusted so that the Nb content was 1.25 mol parts per 100 mol parts total Ti contained in the margin slurry and margin sheet.

[0164] The Nb content of Examples 1-3 and Comparative Examples 1-3 can be measured by TEM-EDS analysis as described above.

[0165] [Evaluation 1: Connectivity between margin coating layer and capacitor body] One hundred multilayer ceramic capacitors were prepared using the methods described above for both the example and the comparative example, and the periphery of each multilayer ceramic capacitor was fixed with epoxy resin.

[0166] The multilayer ceramic capacitor was polished using a polishing machine so that the cross-sections (WT cross-sections) obtained by cutting perpendicular to the length direction (L-axis direction) from the center in the length direction (L-axis direction) in the width direction (W-axis direction) and the stacking direction (T-axis direction) were exposed.

[0167] Focused ion beam (FIB) treatment was performed on the boundary region between the dielectric layer and the margin coating layer of the capacitor body in the exposed WT cross section, and TEM-EDS analysis images were obtained. Specifically, in the WT cross section, a square region was defined with a center line passing through the center of the stacking direction (T-axis direction) of the multilayer ceramic capacitor and extending in the width direction (W-axis direction), with a length of 20 μm in the width direction (W-axis direction) and a length of 200 μm in the stacking direction (T-axis direction). This square region was divided into 10 sub-square regions with a length of 20 μm in the width direction (W-axis direction) and a length of 20 μm in the stacking direction (T-axis direction). TEM-EDS analysis was performed on each of these sub-square regions to determine whether cracks with a major axis length of 0.1 μm or more were observable with the naked eye between the capacitor body and the margin coating layer.

[0168] The number of multilayer ceramic capacitors in which cracks were observed out of 100 was converted to ppm. If the number was 1000 ppm or higher, it was evaluated as 'NG', and if it was less than 1000 ppm, it was evaluated as 'OK'.

[0169] TEM-EDS analysis was performed using a JEOL JEM-ARM 200F / Elite T 1071 under a magnification of 10k and an acceleration voltage of 200kV.

[0170] In the aforementioned evaluation 1, TEM-EDS was used, but the cracks can also be observed and the connectivity evaluated in a similar manner by performing SEM analysis or optical microscopy analysis on the WT cross section.

[0171] Figure 9 shows the scanning electron microscopy-microstructure image database and analysis system (SEM-MiDAS) analysis image of the multilayer ceramic capacitor according to Example 1.

[0172] A Zeiss GeminiSEM360 was used as the SEM instrument. The MiDAS analysis was performed using software (MiDAS2.3) developed by Samsung Electro-Mechanics.

[0173] Figure 10 shows an optical microscope image of a multilayer ceramic capacitor according to Comparative Example 1. Specifically, the multilayer ceramic capacitor of Comparative Example 1 was polished using a polishing machine so that the cross-sections (WT cross-sections) were exposed, which were cut perpendicular to the length direction (L-axis direction) from the center in the length direction (L-axis direction) in the width direction (W-axis direction) and the stacking direction (T-axis direction).

[0174] The optical microscope was set to 100x magnification, and the interface between the margin coating layer and the capacitor body of the WT cross section was photographed to obtain the image shown in Figure 10.

[0175] Referring to Figures 9 and 10, no cracks were observed at the boundary between the capacitor body and the margin coating layer in Example 1, which used a PVB-Nb composite, but cracks were observed in Comparative Example 1.

[0176] [Evaluation 2: Density analysis of the margin coating layer] For the multilayer ceramic capacitors manufactured according to the examples and comparative examples, the periphery of the multilayer ceramic capacitor was fixed with epoxy resin.

[0177] The multilayer ceramic capacitor was polished using a polishing machine so that the cross-sections (WT cross-sections) obtained by cutting perpendicular to the length direction (L-axis direction) from the center in the length direction (L-axis direction) in the width direction (W-axis direction) and the stacking direction (T-axis direction) were exposed.

[0178] SEM-MiDAS analysis images were obtained for the margin coating layer in the WT cross-section. Specifically, in the WT cross-section, a rectangular region was defined with a length of 20 μm in the width direction (W-axis direction) and 200 μm in the stacking direction (T-axis direction), with a center line passing through the center of the stacking direction (T-axis direction) of the multilayer ceramic capacitor and extending in the width direction (W-axis direction). This rectangular region was divided into 10 sub-rectangular regions, each with a length of 20 μm in the width direction (W-axis direction) and 20 μm in the stacking direction (T-axis direction). SEM analysis images were obtained for each of these sub-rectangular regions, and the number of pores was measured using the MiDAS (Microstructure Image Database and Analysis System) 2.3 program. The grain size was also evaluated visually. If the average number of pores in the 10 sub-rectangular regions was 20 or more, it was evaluated as 'NG', and if it was less than 20, it was evaluated as 'OK'.

[0179] Figure 11 shows the SEM-MiDAS analysis image of the multilayer ceramic capacitor according to Example 1. Figure 12 shows the SEM-MiDAS analysis image of the multilayer ceramic capacitor according to Comparative Example 1.

[0180] Referring to Figures 11 and 12, in Example 1, the crystal grain size and pore number of the margin coating layer were relatively smaller compared to Comparative Example 1, resulting in improved density, stability, and moisture resistance reliability of the multilayer ceramic capacitor.

[0181] [Evaluation 3: Moisture Resistance Reliability Analysis] Forty multilayer ceramic capacitors were prepared according to the aforementioned examples and comparative examples. For each multilayer ceramic capacitor, the change in internal resistance (IR) was measured for 12 hours under conditions of 85°C, 95% relative humidity, and 6.3V using an ESPEC (PR-3J, 8585) apparatus to evaluate its operating life.

[0182] If the average operating life of the 40 multilayer ceramic capacitors was 8 hours or less, it was evaluated as 'NG'; if it exceeded 8 hours, it was evaluated as 'OK'.

[0183] Figure 13 is a graph showing the results of the humidity resistance reliability evaluation of the multilayer ceramic capacitor according to Example 1. Figure 14 is a graph showing the results of the humidity resistance reliability evaluation of the multilayer ceramic capacitor according to Example 1.

[0184] Referring to Figures 13 and 14, the internal resistance was maintained relatively stably in Example 1 compared to Comparative Example 1.

[0185] The Nb content per 100 moles of Ti in the margin coating layer and the evaluation results are shown in Table 1 below. In Table 1, the connectivity evaluation results for the margin coating layer and the capacitor body are shown.

[0186] [Table 1]

[0187] As shown in Table 1, in the example where the Nb content of the margin coating layer formed using a margin slurry containing a PVB-Nb composite was 0.5 to 1 mole per 100 moles of Ti, the moisture resistance reliability, connectivity between the margin coating layer and the capacitor body, and density of the margin coating layer were relatively improved compared to the comparative example. As a result, the multilayer ceramic capacitor of the example showed relatively improved structural stability and reliability compared to the multilayer ceramic capacitor of the comparative example. [Explanation of Symbols]

[0188] 100: Multilayer ceramic capacitor 110: Capacitor body 111: Dielectric layer 121: 1st internal electrode 122:Second internal electrode 131: 1st external electrode 132:Second external electrode 141: First margin coating layer 142: Second margin coating layer

Claims

1. A capacitor body having a first and second surface facing each other in a first direction, a third and fourth surface facing each other in a second direction and connecting the first and second surfaces, and a fifth and sixth surface facing each other in a third direction and connecting the first and second surfaces, and comprising a plurality of dielectric layers and a plurality of internal electrodes stacked in the third direction, The external electrode located on the outside of the capacitor body, The third and fourth surfaces include a margin coating layer containing a barium titanate compound and Nb, A multilayer ceramic capacitor in which the Nb content in the margin coating layer is 0.5 moles or more and 1 mole or less per 100 moles of Ti contained in the margin coating layer.

2. The multilayer ceramic capacitor according to claim 1, wherein the maximum length of the margin coating layer in the second direction is greater than 0 μm and 20 μm or less.

3. The multilayer ceramic capacitor according to claim 1, wherein the Nb contained in the margin coating layer is derived from a polyvinyl butyral (PVB)-Nb composite.

4. The multilayer ceramic capacitor according to claim 1, wherein the external electrodes are located on the first surface and the second surface.

5. The multilayer ceramic capacitor according to claim 1, wherein the margin coating layer is in contact with the dielectric layer or the internal electrode.

6. The multilayer ceramic capacitor according to claim 1, wherein the margin coating layer is exposed to the outside.

7. The steps include forming a dielectric green sheet laminate by stacking dielectric green sheets, each having a conductive paste layer on its surface, in a third direction, The steps include cutting the dielectric green sheet laminate in the third direction to form a precapacitor body in which one end of the conductive paste layer is exposed, The steps include firing the precapacitor body to form a capacitor body including a plurality of dielectric layers stacked in the third direction and a plurality of internal electrodes, The steps include applying a margin slurry containing a polyvinyl butyral (PVB)-Nb composite onto a margin sheet, The steps include positioning the margin sheet and the margin slurry on the capacitor body such that the margin slurry covers one exposed end of the internal electrode, The step includes firing the margin slurry and the margin sheet to form a margin coating layer, A method for manufacturing a multilayer ceramic capacitor, wherein the Nb content in the margin coating layer is 0.5 moles or more and 1 mole per 100 moles of Ti contained in the margin coating layer.

8. The method for manufacturing a multilayer ceramic capacitor according to claim 7, wherein the PVB-Nb composite comprises a compound in which PVB and Nb are bonded through chemical bonding.

9. The method for manufacturing a multilayer ceramic capacitor according to claim 7, wherein the PVB-Nb composite comprises a polymer containing repeating units derived from PVB, repeating units derived from polyvinyl alcohol (PVA), and repeating units derived from polyvinyl acetate (PVAc).

10. The method for manufacturing a multilayer ceramic capacitor according to claim 7, wherein the PVB-Nb composite is formed by introducing a PVB source and an Nb source into a solvent, mixing them, and drying them.

11. The method for manufacturing a multilayer ceramic capacitor according to claim 10, wherein the PVB source comprises a polymer including PVB-derived repeating units, PVA-derived repeating units, and PVAc-derived repeating units.

12. The method for manufacturing a multilayer ceramic capacitor according to claim 11, wherein the polymer of the PVB source further comprises repeating units having carboxyl groups at their ends.

13. A method for manufacturing a multilayer ceramic capacitor according to claim 12, wherein Nb ions contained in the Nb source bond to the carboxyl group to form the PVB-Nb composite.

14. The method for manufacturing a multilayer ceramic capacitor according to claim 10, wherein the Nb source comprises niobethoxide (Nb ethoxide).

15. The method for manufacturing a multilayer ceramic capacitor according to claim 7, wherein the margin slurry further comprises a barium titanate-based compound.

16. The capacitor body has a first surface and a second surface facing each other in a first direction, a third surface and a fourth surface facing each other in a second direction and connecting the first surface and the second surface, and a fifth surface and a sixth surface facing each other in a third direction and connecting the first surface and the second surface. The margin coating layer is located on the third and fourth surfaces, The method for manufacturing a multilayer ceramic capacitor according to claim 7, wherein the maximum length of the margin coating layer in the second direction is greater than 0 μm and 20 μm or less.

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