Multilayer ceramic capacitor and method of manufacturing the same

Abstract

To provide a multilayer ceramic capacitor with excellent reliability and a method of manufacturing the same.SOLUTION: A multilayer ceramic capacitor according to an embodiment includes a capacitor body including dielectric layers and internal electrode layers, and external electrodes disposed outside the capacitor body. The external electrodes each include a lower layer positioned on a cross-section of the capacitor body to be electrically connected to at least one of the internal electrode layers, and an upper layer to cover the lower layer and positioned on the lower layer. The lower layer includes a first glass, and the upper layer includes a second glass. The first glass includes aluminum (Al) in an amount of more than 0 atom% to 8 atom% or less with respect to a total amount of components of the first glass, and the second glass includes aluminum (Al) in an amount of 10 atom% or more to 20 atom% or less with respect to a total amount of components of the second glass.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a multilayer ceramic capacitor and a manufacturing method thereof. [Background technology]

[0002] Electronic components using ceramic materials include capacitors, inductors, piezoelectric elements, varistors, thermistors, etc. Among these ceramic electronic components, multilayer ceramic capacitors (MLCCs) have the advantages of being small, high capacity, and easy to mount, and can be used in a variety of electronic devices.

[0003] For example, the multilayer ceramic capacitor can be used as a chip-type capacitor that is mounted on substrates of various electronic products such as visual devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), and organic light-emitting diodes (OLEDs), computers, personal portable terminals, and smartphones to charge or discharge electricity. Summary of the Invention [Problem to be solved by the invention]

[0004] Recently, as electronic products become smaller, multilayer ceramic capacitors are also required to be ultra-small and have ultra-high capacitance. To this end, multilayer ceramic capacitors are being manufactured that have a structure in which the thicknesses of the dielectric layers and internal electrode layers are reduced and a greater number of dielectric layers and internal electrode layers are laminated. These ultra-small and ultra-high capacitance multilayer ceramic capacitors are now being used in fields that require a high level of reliability, such as electric vehicles, and therefore high reliability is required to meet this demand. [Means for solving the problem]

[0005] One embodiment provides a multilayer ceramic capacitor with excellent reliability.

[0006] Another embodiment provides a method for manufacturing the multilayer ceramic capacitor.

[0007] One embodiment provides a multilayer ceramic capacitor including: a capacitor body including a dielectric layer and an internal electrode layer; and an external electrode disposed on an outside of the capacitor body, the external electrode including a lower layer located on a cross section of the capacitor body to be electrically connected to at least one of the internal electrode layers; and an upper layer covering the lower layer and located on the lower layer, the lower layer including a first glass and the upper layer including a second glass, the first glass including aluminum (Al) in an amount of more than 0 and not more than 8 atomic % based on a total amount of components of the first glass, and the second glass including aluminum (Al) in an amount of 10 atomic % to 20 atomic % based on a total amount of components of the second glass.

[0008] The aluminum (Al) contained in the second glass may have an atomic ratio of more than 2 and not more than 100 relative to the aluminum (Al) contained in the first glass.

[0009] The second glass may further include lithium (Li), sodium (Na), iron (Fe), barium (Ba), calcium (Ca), zinc (Zn), boron (B), silicon (Si), tin (Sn), or a combination thereof.

[0010] The second glass may contain the silicon (Si), and the total content of the aluminum (Al) and silicon (Si) may be 20 atomic % or more and 50 atomic % or less with respect to the total amount of the components of the second glass.

[0011] The first glass may further include lithium (Li), sodium (Na), iron (Fe), barium (Ba), calcium (Ca), zinc (Zn), boron (B), silicon (Si), tin (Sn), or a combination thereof.

[0012] The first glass may contain the barium (Ba) and the zinc (Zn), and the total content of the barium (Ba) and the zinc (Zn) may be 50 atomic % or more and 95 atomic % or less of the total amount of the components of the first glass.

[0013] The first glass and the second glass may further contain sodium (Na), and the sodium (Na) contained in the second glass may have an atomic ratio of more than 2 and less than or equal to 100 relative to the sodium (Na) contained in the first glass.

[0014] The first glass and the second glass may further contain iron (Fe), and the iron (Fe) contained in the second glass may have an atomic ratio of more than 2 and less than or equal to 100 relative to the iron (Fe) contained in the first glass.

[0015] At least one of the lower layer and the upper layer may further include a conductive metal.

[0016] 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.

[0017] When a midpoint of the external electrode in a thickness direction of the multilayer ceramic capacitor is referred to as a center portion and a corner portion of the external electrode is referred to as a corner portion, a thickness ratio of the corner portion to the center portion of the external electrode may be 0.1 or more and 0.5 or less.

[0018] The second glass may contain lithium (Li).

[0019] The first glass may further contain lithium (Li), and the lithium (Li) contained in the second glass may have an atomic ratio of more than 1 relative to the lithium (Li) contained in the first glass.

[0020] Another embodiment of the present invention provides a method for manufacturing a capacitor body including the steps of: applying a first paste for forming a lower layer, the first paste including a first glass composition forming a first glass, on one surface of a capacitor body including a dielectric layer and an internal electrode layer; sintering the first paste for forming the lower layer to form a lower layer of an external electrode; applying a second paste for forming an upper layer, the second paste including a second glass composition forming a second glass, on the lower layer of the external electrode; and sintering the second paste for forming the upper layer to form an upper layer of an external electrode, the first glass composition being aluminum oxide (Al 2 O 3 The first glass composition contains aluminum oxide (Al 2 O 3 ) in an amount of 10 to 20 parts by mol relative to 100 parts by mol of the total amount of the second glass composition.

[0021] In still another embodiment, the present invention provides a capacitor body including a dielectric layer and an internal electrode layer, the capacitor body including a first paste for forming a lower layer including a first glass composition forming a first glass; a second paste for forming an upper layer including a second glass composition forming a second glass on the first paste for forming the lower layer; and a capacitor body having the first paste for forming the lower layer and the second paste for forming the upper layer applied thereto, the capacitor body being sintered to form an external electrode including a lower layer and an upper layer, the first glass composition being aluminum oxide (Al 2 O 3 The first glass composition contains aluminum oxide (Al 2 O 3 ) in an amount of 10 to 20 parts by mol relative to 100 parts by mol of the total amount of the second glass composition.

[0022] The first glass composition contains barium oxide (BaO), calcium oxide (CaO), zinc oxide (ZnO), boron oxide (B 2 O3 ), silicon dioxide (SiO 2 ), or a combination thereof.

[0023] The barium oxide (BaO) may be contained in an amount of 10 to 40 parts by mol, the calcium oxide (CaO) may be contained in an amount of 1 to 20 parts by mol, the zinc oxide (ZnO) may be contained in an amount of 10 to 40 parts by mol, and the boron oxide (B 2 O 3 ) may be contained in an amount of 10 parts by mol or more and 40 parts by mol or less, and the silicon dioxide (SiO 2 ) may be contained in an amount of 1 part by mol or more and 20 parts by mol or less.

[0024] The second glass composition is made of lithium oxide (Li 2 O), sodium oxide (Na 2 O), barium oxide (BaO), calcium oxide (CaO), zinc oxide (ZnO), boron oxide (B 2 O 3 ), silicon dioxide (SiO 2 ), iron oxide (Fe 2 O 3 ), or a combination thereof.

[0025] The lithium oxide (Li 2 O) may be contained in an amount of 1 part by mol to 20 parts by mol, and the sodium oxide (Na 2 The barium oxide (BaO) may be contained in an amount of 10 to 40 parts by mol, the calcium oxide (CaO) may be contained in an amount of 1 to 20 parts by mol, the zinc oxide (ZnO) may be contained in an amount of 1 to 20 parts by mol, and the boron oxide (B 2 O 3 ) may be contained in an amount of 10 parts by mol or more and 40 parts by mol or less, and the silicon dioxide (SiO 2 ) may be contained in an amount of 1 part by mol to 20 parts by mol, and the iron oxide (Fe 2O 3 ) may be contained in an amount of 0.1 parts by mol or more and 10 parts by mol or less.

[0026] At least one of the first paste for forming a lower layer and the second paste for forming an upper layer may further include a conductive metal. Effect of the Invention

[0027] The multilayer ceramic capacitor according to an embodiment includes external electrodes having excellent contact with the internal electrodes, corrosion resistance, and moisture resistance, thereby improving reliability. [Brief description of the drawings]

[0028] [Figure 1] 1 is a perspective view illustrating a multilayer ceramic capacitor according to an embodiment; [Diagram 2] 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line II' in FIG. [Diagram 3] 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line II-II' in FIG. [Figure 4] 2 is a schematic diagram showing an external electrode of the multilayer ceramic capacitor according to the embodiment; [Diagram 5] 1 is a SEM analysis image of an external electrode of the multilayer ceramic capacitor according to Example 1. [Figure 6a] 1 is a cross-sectional SEM-EDS analysis image of an upper layer of an external electrode according to Example 1. [Figure 6b] 1 is a cross-sectional SEM-EDS analysis image of a lower layer of an external electrode according to Example 1. [Figure 7a] 1 is a cross-sectional SEM-EDS analysis image of an external electrode of the multilayer ceramic capacitor according to Example 1. [Figure 7b] 13 is a cross-sectional SEM-EDS analysis image of an external electrode of the multilayer ceramic capacitor according to Comparative Example 1. [Figure 8] 4 is a cross-sectional EPMA analysis image of an external electrode of the multilayer ceramic capacitor according to Example 1. [Figure 9a] 4 is a graph showing the moisture resistance reliability of the external electrodes according to Example 1. [Figure 9b] 13 is a graph showing the moisture resistance reliability of the external electrodes according to Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings so that a person having ordinary skill in the art to which the present invention pertains can easily carry out the present invention. In the drawings, parts that are unnecessary for the explanation are omitted in order to clearly explain the present invention, and the same reference numerals are used for the same or similar components throughout the specification. In addition, in the accompanying drawings, some components are exaggerated, omitted, or illustrated in a schematic manner, and the size of each component does not completely reflect the actual size.

[0030] The attached drawings are merely intended to facilitate understanding of the embodiments disclosed in this specification, and the attached drawings do not limit the technical ideas disclosed in this specification, and it should be understood that the drawings include all modifications, equivalents, and alternatives included in the idea and technical scope of the present invention.

[0031] Terms including ordinal numbers such as first, second, etc. may be used to describe various components, but the components are not limited to the terms. The terms are used only to distinguish one component from another.

[0032] In addition, when a part such as a layer, film, region, or plate is said to be "on" or "above" another part, this includes not only the case where it is "directly on" another part, but also the case where there is another part in between. Conversely, when a part is said to be "directly on" another part, it means that there is no other part in between. In addition, being "on" or "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "on" or "above" the side opposite to gravity.

[0033] Throughout the specification, the terms "comprise" or "have" and the like are intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof described in the specification, but should be understood not to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Thus, when a part is said to "comprise" a certain element, this means that it can further include other elements, but not to the exclusion of other elements, unless specifically stated to the contrary.

[0034] Also, throughout the specification, "in a plane" means when the subject part is viewed from above, and "in cross section" means when the subject part is cut vertically and viewed from the side.

[0035] In addition, throughout the specification, when the term "connected" is used, this does not only mean that two or more components are directly connected, but also that two or more components are indirectly connected through other components, or that two or more components are not only physically connected but also electrically connected, or that components are referred to by different names depending on their location or function but are integrated.

[0036] Hereinafter, a multilayer ceramic capacitor according to an embodiment will be described with reference to FIGS.

[0037] FIG. 1 is a perspective view showing a multilayer ceramic capacitor according to an embodiment, FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line II' in FIG. 1, FIG. 3 is a cross-sectional view of the multilayer ceramic capacitor taken along line II-II' in FIG. 1, and FIG. 4 is a schematic view showing an external electrode of the multilayer ceramic capacitor according to an embodiment.

[0038] The L axis, W axis, and T axis shown in Figs. 1 to 3 indicate the length direction, width direction, and thickness direction of the capacitor body 110, respectively. Here, the thickness direction (T axis direction) may be a direction perpendicular to the wide surface (main surface) of the sheet-shaped component, and may be used as the same concept as the lamination direction in which the dielectric layers 111 are laminated, for example. The length direction (L axis direction) may be a direction extending parallel to the wide surface (main surface) of the sheet-shaped component and approximately perpendicular to the thickness direction (T axis direction), and may be a direction in which the first external electrode 131 and the second external electrode 132 are located on both sides, for example. The width direction (W axis direction) may be a direction extending parallel to the wide surface (main surface) of the sheet-shaped component and approximately perpendicular to the thickness direction (T axis direction) and the length direction (L axis direction), and the length of the sheet-shaped component in the length direction (L axis direction) may be longer than the length of the width direction (W axis direction).

[0039] 1 to 4, a multilayer ceramic capacitor 100 according to an embodiment includes a capacitor body 110 and external electrodes 131 and 132 disposed on the outer side of the capacitor body 110. The external electrodes 131 and 132 may include a first external electrode 131 and a second external electrode 132 disposed on opposite ends of the capacitor body 110 in a longitudinal direction (L-axis direction).

[0040] As an example, the capacitor body 110 may have a substantially hexahedral shape.

[0041] For the sake of convenience in describing one embodiment, the two surfaces of the capacitor body 110 that face each other in the thickness direction (T-axis direction) are defined as the first surface and the second surface, the two surfaces connected to the first surface and the second surface and facing each other in the length direction (L-axis direction) are defined as the third surface and the fourth surface, and the two surfaces connected to the first surface and the second surface and connected to the third surface and the fourth surface and facing each other in the width direction (W-axis direction) are defined as the fifth surface and the sixth surface.

[0042] As an example, the first surface, which is the lower surface, may be the surface facing the mounting direction. The first to sixth surfaces may be flat, but the embodiment is not limited to this. For example, the first to sixth surfaces may be curved surfaces with a convex center, and the corners at the boundaries between the surfaces may be rounded.

[0043] The shape and size of the capacitor body 110 and the number of laminated dielectric layers 111 are not limited to those shown in the drawings of this embodiment.

[0044] The capacitor body 110 includes a plurality of dielectric layers 111 and internal electrode layers 121 and 122. Specifically, the capacitor body 110 includes a plurality of dielectric layers 111 and first internal electrodes 121 and second internal electrodes 122 that are alternately arranged in a thickness direction (T-axis direction) with the dielectric layers 111 sandwiched therebetween.

[0045] The capacitor body 110 will be described in detail later.

[0046] [External electrode] 2 and 4, the external electrodes 131, 132, i.e., the first external electrode 131 and the second external electrode 132, are provided with voltages of different polarities and can be electrically connected to exposed portions of the first internal electrode 121 and the second internal electrode 122, respectively.

[0047] With the above configuration, when a predetermined voltage is applied to the first external electrode 131 and the second external electrode 132, charges are stored 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 overlapping each other along the T-axis direction in the active region.

[0048] The first external electrode 131 and the second external electrode 132 may each include a first connection portion and a second connection portion arranged on the third and fourth surfaces of the capacitor body 110, respectively, and connected to the first internal electrode 121 and the second internal electrode 122, and a first band portion and a second band portion arranged at the corner where the third and fourth surfaces of the capacitor body 110 meet the first and second surfaces or the fifth and sixth surfaces.

[0049] The first and second band parts extend from the first and second connecting parts to parts of the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110. The first and second band parts may serve to improve the bonding strength between the first and second external electrodes 131 and 132.

[0050] The external electrodes 131, 132 include lower layers 10, 30 located on a cross section of the capacitor body 110 to be electrically connected to at least one of the internal electrode layers 121, 122, and upper layers 20, 40 covering the lower layers 10, 30 and located on the lower layers 10, 30. Specifically, the first external electrode 131 includes a first lower layer 10 located on a cross section of the capacitor body 110 to be electrically connected to the first internal electrode 121, and a first upper layer 20 covering the first lower layer 10 and located on the first lower layer 10. In addition, the second external electrode 132 includes a second lower layer 30 located on a cross section of the capacitor body 110 to be electrically connected to the second internal electrode 122, and a second upper layer 40 covering the second lower layer 30 and located on the second lower layer 30.

[0051] The lower layers 10, 30 and the upper layers 20, 40 each contain glass having a different composition. The external electrodes are formed of at least two layers, each containing a glass component with a different composition, which not only provides excellent contact with the internal electrodes, but also prevents the penetration of moisture and plating solution, thereby providing external electrodes with excellent corrosion resistance and moisture resistance. This allows a multilayer ceramic capacitor with improved reliability to be realized.

[0052] The lower layers 10, 30 include a first glass, the first glass including aluminum (Al), and the upper layers 20, 40 include a second glass, the second glass including aluminum (Al).

[0053] Specifically, the aluminum (Al) contained in the lower layer 10, 30 may be more than 0 and less than 8 atomic % based on the total amount of the components of the first glass, for example, 0.1 atomic % to 7.9 atomic % or less, for example, 0.5 atomic % to 7.7 atomic % or less. The aluminum (Al) contained in the upper layer 20, 40 may be more than 10 atomic % to 20 atomic % based on the total amount of the components of the second glass, for example, 11 atomic % to 19 atomic % or less, for example, 12 atomic % to 18 atomic % or less. When the lower layer 10, 30 and the upper layer 20, 40 each contain aluminum (Al) within the above content range as a glass component, it is possible to secure an external electrode with excellent corrosion resistance and moisture resistance reliability by preventing the penetration of moisture and plating solution as well as excellent contact with the internal electrode. The multilayer ceramic capacitor including such an external electrode can improve reliability.

[0054] For example, the aluminum (Al) contained in the second glass of the upper layers 20, 40 may have an atomic ratio of more than 2 and not more than 100 relative to the aluminum (Al) contained in the first glass of the lower layers 10, 30, for example, an atomic ratio of 3 or more and not more than 80. When the atomic ratios of aluminum (Al) contained in the lower layers 10, 30 and the upper layers 20, 40 are within the above ranges, it is possible to ensure external electrodes that have excellent contact with internal electrodes and excellent corrosion resistance and moisture resistance reliability, thereby improving the reliability of the multilayer ceramic capacitor.

[0055] The aluminum (Al) contained in the first glass and the aluminum (Al) contained in the second glass may be a component derived from aluminum oxide added to the lower layer forming paste and the upper layer forming paste, respectively, when forming the external electrodes.

[0056] The first glass of the lower layer 10, 30 may further contain, in addition to aluminum (Al), lithium (Li), sodium (Na), iron (Fe), barium (Ba), calcium (Ca), zinc (Zn), boron (B), silicon (Si), tin (Sn), or a combination thereof.

[0057] Lithium (Li), sodium (Na) and iron (Fe) that can be contained in the first glass are lithium oxide (Li) added to the paste for forming the upper layer when forming the external electrodes. 2 O), sodium oxide (Na 2 O), and iron oxide (Fe 2 O 3 That is, the additive may be a component that partially diffuses into the lower layer while forming the upper layer. In addition, barium (Ba), calcium (Ca), zinc (Zn), boron (B), and silicon (Si) that can be contained in the first glass may be barium oxide (BaO), calcium oxide (CaO), zinc oxide (ZnO), boron oxide (B), and silicon oxide (Si) that are added to the paste for forming the lower layer that is applied when forming the external electrodes. 2 O 3 ), and silicon dioxide (SiO 2 ) may be components derived from each of the above.

[0058] As an example, the first glass may contain aluminum (Al), barium (Ba), and zinc (Zn). The first glass may be a Ba / Zn-based glass in which the total of barium (Ba) and zinc (Zn) components is the largest part of the total components of the first glass. For example, the total of barium (Ba) and zinc (Zn) components may be 50 atomic % to 95 atomic % or 55 atomic % to 90 atomic % of the total components of the first glass. When the first glass has a composition within the above range, an external electrode having excellent connectivity with the internal electrode, i.e., excellent contactability, can be obtained.

[0059] The second glass of the upper layer 20, 40 may further include, in addition to aluminum (Al), lithium (Li), sodium (Na), iron (Fe), barium (Ba), calcium (Ca), zinc (Zn), boron (B), silicon (Si), tin (Sn), or combinations thereof.

[0060] The lithium (Li), sodium (Na), and iron (Fe) that can be contained in the second glass are lithium oxide (Li) added to the paste for forming the upper layer when forming the external electrodes. 2 O), sodium oxide (Na 2 O), and iron oxide (Fe 2 O 3 In addition, barium (Ba), calcium (Ca), zinc (Zn), boron (B), and silicon (Si) that can be contained in the second glass can be barium oxide (BaO), calcium oxide (CaO), zinc oxide (ZnO), boron oxide (B) that are added to the paste for forming the upper layer that is applied when forming the external electrodes. 2 O 3 ), and silicon dioxide (SiO 2 ) may be components derived from each of the above.

[0061] As an example, the second glass may contain aluminum (Al) and silicon (Si). The second glass may be an Al / Si-based glass in which the total of aluminum (Al) and silicon (Si) components accounts for a major portion of the total components of the second glass. For example, the total of aluminum (Al) and silicon (Si) components may be 20 atomic % or more and 50 atomic % or less, or 22 atomic % or more and 40 atomic % or less, relative to the total amount of the components of the second glass. When the second glass has a composition within the above range, an external electrode having excellent corrosion resistance and moisture resistance reliability can be obtained.

[0062] When Ba / Zn-based glass is used alone to form the external electrodes, it has excellent contact with the internal electrodes, but is corroded by the plating solution, making it difficult to ensure reliability, and when Al / Si-based glass is used alone, it has high corrosion resistance to the plating solution and is highly reliable, but poor contact with the internal electrodes may occur due to low contact with metals. According to one embodiment, the external electrodes are formed of at least two layers, including a lower layer corresponding to Ba / Zn-based glass and an upper layer corresponding to Al / Si-based glass, thereby ensuring the external electrodes having excellent contact with the internal electrodes, corrosion resistance to the plating solution, and moisture resistance. Therefore, a multilayer ceramic capacitor with excellent reliability can be realized.

[0063] Also, as an example, the first glass of the lower layer 10, 30 and the second glass of the upper layer 20, 40 may contain sodium (Na). In this case, the sodium (Na) contained in the second glass may have an atomic ratio of more than 2 and not more than 100 to the sodium (Na) contained in the first glass, for example, an atomic ratio of 3 or more and not more than 80. When the atomic ratios of sodium (Na) contained in the lower layer 10, 30 and the upper layer 20, 40, respectively, are within the above ranges, an external electrode having excellent contact with the internal electrode and excellent corrosion resistance and moisture resistance reliability can be ensured.

[0064] As an example, the first glass of the lower layer 10, 30 and the second glass of the upper layer 20, 40 may contain iron (Fe). In this case, the iron (Fe) contained in the second glass may have an atomic ratio of more than 2 and not more than 100 to the iron (Fe) contained in the first glass, for example, an atomic ratio of 3 or more and not more than 80. When the atomic ratio of sodium (Na) contained in each of the lower layer 10, 30 and the upper layer 20, 40 is within the above range, an external electrode having excellent contact with the internal electrode and excellent corrosion resistance and moisture resistance reliability can be ensured.

[0065] It can be confirmed by SEM (Scanning Electron Microscope) analysis that the external electrodes 131, 132 according to an embodiment are formed to include the lower layers 10, 30 and the upper layers 20, 40 as described above.

[0066] The SEM analysis can be performed in the following manner. After the multilayer ceramic capacitor 100 is immersed in an epoxy mixture and cured, it is polished using sand paper and a diamond suspension to obtain a cross-sectional sample having an LT surface so that the external electrodes can be observed. The cross-sectional sample obtained can then be measured using a scanning electron microscope (SEM). For example, the SEM can be measured using a Tescan Vega3 under conditions of 20 kV, 0.2 nA, and 3k magnification.

[0067] In addition, the composition of the components contained in the lower layers 10, 30 and the upper layers 20, 40, specifically the atomic percentages and atomic ratios of aluminum (Al), silicon (Si), barium (Ba), zinc (Zn), sodium (Na), iron (Fe), etc. in each layer can be confirmed by SEM-EDS (scanning electron microscope-energy dispersive spectroscopy) analysis or EPMA (electron probe microanalyzer).

[0068] The SEM-EDS analysis can be performed in the following manner. First, a cross-sectional sample can be obtained from the multilayer ceramic capacitor 100 in the manner described above. The obtained cross-sectional sample can then be measured using a scanning electron microscope (SEM). For example, the SEM can be measured using a Tescan Vega3 under conditions of 20 kV, 0.2 nA, and an analysis magnification of 6005 times. Next, an EDS (energy dispersive spectroscopy) analysis can be performed on the SEM image of the measured cross-sectional sample to confirm the content of each component present in the lower layer and upper layer of the external electrode.

[0069] EPMA can be used for analysis in the following manner. First, a cross-sectional sample can be obtained from the multilayer ceramic capacitor 100 in the manner described above. The cross-sectional sample obtained is subjected to EPMA (Electron Probe Microanalyzer) analysis under conditions of a voltage of 15 kV and a magnification of 10 kV to confirm the mapping and elemental content of each element present in the lower and upper layers of the external electrodes.

[0070] The lower layers 10, 30 and the upper layers 20, 40 may be sintered metal layers of the external electrodes.

[0071] At least one of the lower layers 10, 30 and the upper layers 20, 40 may further include a conductive metal. That is, either one of the lower layers 10, 30 and the upper layers 20, 40 may include a conductive metal, or all of the lower layers 10, 30 and the upper layers 20, 40 may include a conductive metal.

[0072] 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, such as copper (Cu) or a copper (Cu) alloy.

[0073] When the conductive metal contains copper (Cu), metals other than copper (Cu) may be contained in an amount of 5 parts by mol or less per 100 parts by mol of copper (Cu).

[0074] The conductive metal contained in the lower layers 10, 30 may be present in an amount of 80% by weight or more and 99% by weight or less based on the total amount of the lower layers, and the conductive metal contained in the upper layers 20, 40 may be present in an amount of 80% by weight or more and 99% by weight or less based on the total amount of the upper layers.

[0075] 2, the midpoint of the length of the external electrodes 131, 132 in the thickness direction (T-axis direction) of the multilayer ceramic capacitor 100 may be referred to as a center portion A, and the corner portion of the multilayer ceramic capacitor 100 may be referred to as a corner portion B. That is, the center portion A may be a midpoint of the length of the third and fourth sides, and the corner portion B may be a point where the three sides meet.

[0076] According to an embodiment, the corner portion B of the external electrodes 131, 132 includes the lower layer 10, 30 and the upper layer 20, 40, i.e., forms at least a double layer, so that the thickness of the corner portion B can be increased. The corner portion B can be one of the permeation paths of the plating solution. According to an embodiment, the increased thickness of the corner portion B can block the permeation of the plating solution, thereby improving the corrosion resistance and moisture resistance reliability.

[0077] For example, the thickness ratio of the corner portion B to the center portion A of the external electrodes 131, 132 may be 0.1 to 0.5, for example, 0.15 to 0.45. When the thickness ratio of the corner portion B to the center portion A of the external electrodes 131, 132 is within the above range, the corrosion resistance and moisture resistance reliability can be improved.

[0078] The thicknesses of the central portion A and the corner portion B of the external electrodes 131, 132 can be measured by SEM (scanning electron microscope) analysis. The SEM analysis can be performed in the same manner as the SEM analysis method for confirming the formation of the lower layers 10, 30 and the upper layers 20, 40 as described above.

[0079] The external electrodes 131 and 132 may further include a conductive resin layer disposed on the upper layers 20 and 40 to cover the lower layers 10 and 30 and the upper layers 20 and 40, and a plating layer disposed to cover the conductive resin layer.

[0080] The conductive resin layer extends to the first and second sides or the fifth and sixth sides of the capacitor body 110, and the length of the region (i.e., band portion) where the conductive resin layer is extended to the first and second sides or the fifth and sixth sides of the capacitor body 110 may be longer than the length of the region (i.e., band portion) where the upper layers 20, 40 are extended to the first and second sides or the fifth and sixth sides of the capacitor body 110. That is, the conductive resin layer is formed on the upper layers 20, 40 to completely cover the upper layers 20, 40.

[0081] The conductive resin layer includes a resin and a conductive metal.

[0082] The resin contained in the conductive resin layer is not particularly limited as long as it has bonding and impact absorbing properties and can be mixed with the conductive metal powder to form a paste, and may include, for example, a phenolic resin, an acrylic resin, a silicone resin, an epoxy resin, or a polyimide resin.

[0083] The conductive metal contained in the conductive resin layer serves to electrically connect the internal electrode layers 121 and 122 or the lower layers 10 and 30 and the upper layers 20 and 40 .

[0084] The conductive metal contained in the conductive resin layer may have a spherical shape, a flake shape, or a combination thereof, that is, the conductive metal may be only in a flake shape, only in a spherical shape, or in a mixed shape of a flake shape and a spherical shape.

[0085] Here, the spherical shape may include a shape that is not a perfect sphere, for example, a shape in which the ratio of the major axis to the minor axis (major axis / minor axis) is 1.45 or less. The flake-shaped powder means a powder having a flat and elongated shape, and is not particularly limited, and may be, for example, a ratio of the major axis to the minor axis (major axis / minor axis) of 1.95 or more.

[0086] 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) alone or an alloy thereof. For example, the plating layer may be a nickel (Ni) plating layer or a tin (Sn) plating layer, or may be a form in which a nickel (Ni) plating layer and a tin (Sn) plating layer are sequentially laminated, or a form in which a tin (Sn) plating layer, a nickel (Ni) plating layer, and a tin (Sn) plating layer are sequentially laminated. Also, the plating layer may include a plurality of nickel (Ni) plating layers and / or a plurality of tin (Sn) plating layers.

[0087] The plating layer can improve the mountability of the multilayer ceramic capacitor 100 on a substrate, structural reliability, durability against external forces, heat resistance, and equivalent series resistance (ESR).

[0088] [Capacitor body] The capacitor body 110 includes a plurality of dielectric layers 111 and internal electrode layers 121 and 122. Specifically, the capacitor body 110 includes a plurality of dielectric layers 111, and first internal electrodes 121 and second internal electrodes 122 that are alternately arranged in the thickness direction (T-axis direction) with the dielectric layers 111 sandwiched therebetween.

[0089] At this time, the boundaries between the adjacent dielectric layers 111 of the capacitor body 110 are integrated to such an extent that they are difficult to see without using a scanning electron microscope (SEM).

[0090] The capacitor body 110 may include an active area. The active area is a portion that contributes to forming the capacitance of the multilayer capacitor 100. For example, the active area may be an overlapping area of ​​the first internal electrode 121 or the second internal electrode 122 that are stacked in the thickness direction (T-axis direction).

[0091] In addition, the capacitor body 110 may further include a cover region and a side margin region.

[0092] The cover region is a thickness direction marginal portion and may be disposed on the first and second sides of the active region in the thickness direction (T-axis direction). Such a cover region may be a single dielectric layer 111 or two or more dielectric layers 111 stacked on the upper and lower surfaces of the active region, respectively.

[0093] The side margin regions are widthwise margins and may be disposed on the fifth and sixth surfaces of the active region in the widthwise direction (W-axis direction). Such side margin regions may be formed by applying a conductive paste layer for an internal electrode to only a part of the surface of the dielectric green sheet when applying the conductive paste layer to the surface of the dielectric green sheet, laminating dielectric green sheets not coated with the conductive paste layer on both sides of the surface of the dielectric green sheet, and then firing the laminate.

[0094] The cover region and the side margin region serve to prevent the first internal electrode 121 and the second internal electrode 122 from being damaged by physical or chemical stress.

[0095] The dielectric layer 111 contains a barium titanate-based main component.

[0096] The barium titanate-based main component is a dielectric base material that has a high dielectric constant and contributes to the formation of the dielectric constant of the multilayer ceramic capacitor 100 .

[0097] The main component of barium titanate is, for example, BaTiO 3 , Ba(Ti,Zr)O 3 , Ba(Ti,Sn)O 3 , (Ba,Ca)TiO 3 , (Ba,Ca)(Ti,Zr)O 3 , (Ba,Ca)(Ti,Sn)O 3 , (Ba,Sr)TiO 3 , (Ba,Sr)(Ti,Zr)O 3, (Ba,Sr)(Ti,Sn)O 3 , or a combination thereof.

[0098] The dielectric layer 111 may further include a minor component, such as 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), or a combination thereof.

[0099] The average thickness (average length in the T-axis direction) of the dielectric layer 111 may be 2.0 μm or more and 8.0 μm or less, for example, 2.4 μm or more and 7.8 μm or less. When the average thickness of the dielectric layer 111 is within the above range, the reliability of the multilayer ceramic capacitor is excellent. This can be obtained as an arithmetic average value of the thickness of the dielectric layer 111 at 10 points spaced apart from the reference point at a predetermined interval, using the center point of the dielectric layer 111 in the length direction (L-axis direction) or width direction (W-axis direction) as a reference point in a scanning electron microscope (SEM) image of the cross-sectional sample measured as described above. The interval between the 10 points can be adjusted according to the scale of the scanning electron microscope (SEM) image, and may be, for example, 1 μm or more and 100 μm or less, 1 μm or more and 50 μm or less, or 1 μm or more and 10 μm or less. In this case, all of the 10 points must be located within the dielectric layer 111, and if all of the 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.

[0100] The internal electrode layers 121, 122, i.e., the first internal electrode 121 and the second internal electrode 122, are electrodes having different polarities and are alternately arranged to face each other along the T-axis direction across the dielectric layer 111, and one end is exposed through the third and fourth surfaces of the capacitor body 110, respectively.

[0101] The first internal electrode 121 and the second internal electrode 122 can be electrically insulated from each other by the dielectric layer 111 disposed therebetween.

[0102] Ends of the first internal electrode 121 and the second internal electrode 122 alternately exposed through the third and fourth surfaces of the capacitor body 110 may be electrically connected to the first external electrode 131 and the second external electrode 132, respectively.

[0103] The first internal electrode 121 and the second internal electrode 122 include a conductive metal, and may include, for example, a metal such as Ni, Cu, Ag, Pd, or Au, or an alloy thereof, such as an Ag-Pd alloy.

[0104] Furthermore, the first internal electrode 121 and the second internal electrode 122 may contain dielectric particles having the same composition as the ceramic material contained in the dielectric layer 111 .

[0105] The first internal electrode 121 and the second internal electrode 122 may be formed using a conductive paste containing a conductive metal. The conductive paste may be printed by screen printing or gravure printing.

[0106] The average thickness of the first internal electrode 121 and the second internal electrode 122 may be 0.1 μm or more and 2 μm or less. The average thickness of the first internal electrode 121 and the second internal electrode 122 may be measured by scanning electron microscope (SEM) analysis. Here, the scanning electron microscope (SEM) analysis is the same as the method for measuring the average thickness of the dielectric layer 111 described above, and therefore the description thereof will be omitted.

[0107] The capacitor body 110 may be formed by firing a laminate in which a plurality of dielectric layers 111 and internal electrode layers 121 and 122 are laminated.

[0108] A method for manufacturing the multilayer ceramic capacitor 100 according to an embodiment will be described below.

[0109] [Manufacturing method of multilayer ceramic capacitor] According to one embodiment, the multilayer ceramic capacitor 100 may include the steps of: applying a first paste for forming a lower layer, the first paste including a first glass composition forming a first glass, to one surface of a capacitor body 110 including a dielectric layer 111 and internal electrode layers 121, 122; sintering the first paste for forming the lower layer to form the lower layers 10, 30 of the external electrodes 131, 132; applying a second paste for forming an upper layer, the second paste including a second glass composition forming a second glass, on the lower layers 10, 30 of the external electrodes 131, 132; and sintering the second paste for forming the upper layer to form the upper layers 20, 40 of the external electrodes 131, 132.

[0110] In addition, according to one embodiment, the multilayer ceramic capacitor 100 may include a step of applying a first paste for forming a lower layer, the first paste including a first glass composition forming a first glass, to one surface of a capacitor body 110 including a dielectric layer 111 and internal electrode layers 121 and 122; applying a second paste for forming an upper layer, the second paste including a second glass composition forming a second glass, on the first paste for forming the lower layer; and sintering the capacitor body to which the first paste for forming the lower layer and the second paste for forming the upper layer are applied, to form external electrodes 131 and 132 including lower layers 10 and 30 and upper layers 20 and 40.

[0111] First, a method for manufacturing the capacitor body 110 will be described.

[0112] The capacitor body 110 may be manufactured through the steps of: preparing a dielectric green sheet using a dielectric slurry, forming a conductive paste layer on a surface of the dielectric green sheet; laminating the dielectric green sheets on which the conductive paste layer is formed to prepare a dielectric green sheet laminate; and firing the dielectric green sheet laminate.

[0113] The dielectric slurry can be produced by mixing a barium titanate-based main component powder and, optionally, a subcomponent powder.

[0114] The barium titanate-based main component powder is the same as the barium titanate-based main component contained in the dielectric layer, and therefore a description thereof will be omitted here.

[0115] The secondary component powders may include, but are not limited to, 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 combinations thereof. Each of the subcomponent powders may be contained in an amount of 0.01 to 5 parts by mol relative to 100 parts by mol of the barium titanate-based main component powder.

[0116] The auxiliary component powders can be used in the form of oxides or salt compounds containing the respective metals, or in the form of a sol dispersed in an organic solvent.

[0117] The dielectric slurry may be prepared by additionally mixing additives such as a dispersant, a binder, a plasticizer, a lubricant, an antistatic agent, and a solvent.

[0118] A wet ball mill or an agitation mill can be used to mix the barium titanate-based main component powder and the optional subcomponent powder. When using zirconia balls in a wet ball mill, wet mixing can be performed for 8 hours to 48 hours, or for 10 hours or 24 hours, using a large number of zirconia balls with a diameter of 0.1 mm to 10 mm.

[0119] The produced dielectric slurry is formed into a dielectric layer after firing.

[0120] The produced dielectric slurry can be molded into a sheet shape using a tape molding method such as a doctor blade method or a calendar roll method, for example, a head-discharging on-roll molding coater, and then the molded product can be dried to obtain a dielectric green sheet.

[0121] To form a conductive paste layer that will become an internal electrode layer after firing, a conductive paste can be manufactured by mixing a conductive powder made of a conductive metal or its alloy, a binder, and a solvent. If necessary, barium titanate powder can be mixed in as a co-material. The co-material can suppress the sintering of the conductive powder during the firing process. The conductive paste is applied in a predetermined pattern to the surface of the dielectric green sheet by various printing methods such as screen printing or transfer method to form a conductive paste layer.

[0122] The conductive powder may include nickel (Ni) or a nickel (Ni) alloy.

[0123] Next, the dielectric green sheets on which the internal electrode patterns are formed are laminated in a plurality of layers and pressed in the lamination direction to manufacture a dielectric green sheet laminate. At this time, the dielectric green sheets and the internal electrode patterns can be laminated such that the dielectric green sheets are located on the upper and lower surfaces of the dielectric green sheet laminate in the lamination direction.

[0124] The manufactured dielectric green sheet laminate may be optionally cut into a predetermined size by dicing or the like.

[0125] Furthermore, the dielectric green sheet laminate can be solidified and dried to remove plasticizers, etc., if necessary, and after solidification and drying, can be barrel polished using a horizontal centrifugal barrel polishing machine, etc. In barrel polishing, the dielectric green sheet laminate is placed in a barrel container together with media and polishing liquid, and unnecessary parts such as burrs generated during cutting can be polished by applying rotational motion, vibration, etc. to the barrel container. Furthermore, after barrel polishing, the dielectric green sheet laminate can be washed with a cleaning liquid such as water and dried.

[0126] The dielectric green sheet laminate is then debindered and fired to produce a capacitor body.

[0127] The binder removal treatment conditions can be appropriately adjusted depending on the components of the dielectric layer and the internal electrode layer. For example, the temperature rise 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 treatment may be performed in air or a reducing atmosphere.

[0128] The firing conditions 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, firing can be performed at a temperature of 1100°C to 1400°C, for example, 1200°C to 1350°C. Also, firing can be performed for 0.5 hours to 8 hours, for example, 1 hour to 3 hours. Also, firing can be performed in a reducing atmosphere, for example, an atmosphere containing a humidified mixed gas of nitrogen and hydrogen. When the internal electrodes contain nickel (Ni) or a nickel (Ni) alloy, the oxygen partial pressure in the firing atmosphere is 1.0×10 -14 MPa or more 1.0×10 -10 MPa or less.

[0129] After the firing treatment, annealing can be performed if necessary. Annealing is a treatment for reoxidizing the dielectric layer, and can be performed when the firing treatment is performed in a reducing atmosphere. The conditions of the annealing treatment can also be appropriately adjusted depending on the components of the dielectric layer. For example, the temperature during annealing can be 950°C or higher and 1150°C or lower, the time can be 0 hours or higher and 20 hours or lower, and the temperature rise rate can be 50°C / hour or higher and 500°C / hour or lower. The annealing atmosphere is humidified nitrogen gas (N 2 ) atmosphere, with an oxygen partial pressure of 1.0×10 -9 MPa or more 1.0×10 -5 MPa or less.

[0130] In the binder removal treatment, firing treatment, or annealing treatment, a wetter, for example, may be used to wet the nitrogen gas or mixed gas, and in this case, the water temperature may be 5° C. or more and 75° C. or less. The binder removal treatment, firing treatment, and annealing treatment may be performed consecutively or independently.

[0131] Optionally, the third and fourth surfaces of the manufactured capacitor body 110 may be subjected to surface treatment such as sandblasting, laser irradiation, barrel polishing, etc. By performing such surface treatment, ends of the first and second internal electrodes are exposed on the outermost surfaces of the third and fourth surfaces, which may improve electrical connection between the first and second external electrodes and the first and second internal electrodes, making it easier to form an alloy part.

[0132] A method for manufacturing the external electrodes 131 and 132 will now be described.

[0133] A first paste for forming a lower layer is applied to one surface of the manufactured capacitor body 110 and sintered to form the lower layers 10, 30, and then a second paste for forming an upper layer is applied on the lower layers 10, 30 and sintered to form the upper layers 20, 40, thereby manufacturing the external electrodes 131, 132. Alternatively, a first paste for forming a lower layer is applied to one surface of the manufactured capacitor body 110, and then a second paste for forming an upper layer is applied thereon and sintered to form the lower layers 10, 30 and the upper layers 20, 40, thereby manufacturing the external electrodes 131, 132.

[0134] The first paste for forming the lower layer includes a first glass composition for forming a first glass, and the first glass composition includes aluminum oxide (Al 2 O 3 The second paste for forming the upper layer includes a second glass composition for forming a second glass, and the second glass composition includes aluminum oxide (Al 2 O 3 ).

[0135] Specifically, the aluminum oxide (Al 2 O 3 ) may be contained in an amount of more than 0 and not more than 8 molar parts relative to 100 molar parts of the total amount of the first glass composition, for example, 0.1 molar parts or more and 7.9 molar parts or less, for example, 0.5 molar parts or more and 7.7 molar parts or less. In addition, aluminum oxide (Al 2 O 3 The second glass composition may contain 10 to 20 parts by mol, for example, 11 to 19 parts by mol, for example, 12 to 18 parts by mol, based on 100 parts by mol of the total amount of the second glass composition. The first paste for forming the lower layer and the second paste for forming the upper layer each contain aluminum oxide (Al) within the above content range as a glass component. 2 O 3 In the case where the conductive layer contains the conductive material, it is possible to manufacture an external electrode that has excellent contact with the internal electrodes and also prevents the penetration of moisture and plating solution, thereby having excellent corrosion resistance and moisture resistance reliability.

[0136] The first glass composition of the first paste for forming the lower layer is composed of barium oxide (BaO), calcium oxide (CaO), zinc oxide (ZnO), boron oxide (B 2 O 3 ), silicon dioxide (SiO 2 ), or a combination thereof.

[0137] Barium oxide (BaO) may be contained in an amount of 10 to 40 molar parts, for example, 15 to 35 molar parts, relative to a total of 100 molar parts of the first glass composition. Calcium oxide (CaO) may be contained in an amount of 1 to 20 molar parts, for example, 5 to 15 molar parts, relative to a total of 100 molar parts of the first glass composition. Zinc oxide (ZnO) may be contained in an amount of 10 to 40 molar parts, for example, 15 to 35 molar parts, relative to a total of 100 molar parts of the first glass composition. Boron oxide (B 2 O 3 Silicon dioxide (SiO 2 ) may be included in an amount of 1 to 20 parts by mole, or 5 to 15 parts by mole, based on 100 parts by mole of the total amount of the first glass composition. When each component is included within the above content range as the first glass composition when forming the first paste for forming the lower layer, an external electrode having excellent contact with the internal electrode, corrosion resistance, and moisture resistance reliability can be manufactured.

[0138] The second glass composition of the second paste for forming the upper layer is lithium oxide (Li 2 O), sodium oxide (Na 2 O), barium oxide (BaO), calcium oxide (CaO), zinc oxide (ZnO), boron oxide (B 2 O 3 ), silicon dioxide (SiO 2 ), iron oxide (Fe 2 O 3 ), or a combination thereof.

[0139] Lithium oxide (Li 2 Sodium oxide (NaO) may be contained in an amount of 1 to 20 parts by mol, for example, 5 to 15 parts by mol, relative to 100 parts by mol of the total amount of the second glass composition. 2 O) may be contained in an amount of 1 to 20 molar parts, for example, 3 to 15 molar parts, relative to a total of 100 molar parts of the second glass composition. Barium oxide (BaO) may be contained in an amount of 10 to 40 molar parts, for example, 15 to 35 molar parts, relative to a total of 100 molar parts of the second glass composition. Calcium oxide (CaO) may be contained in an amount of 1 to 20 molar parts, for example, 5 to 15 molar parts, relative to a total of 100 molar parts of the second glass composition. Zinc oxide (ZnO) may be contained in an amount of 1 to 20 molar parts, for example, 5 to 15 molar parts, relative to a total of 100 molar parts of the second glass composition. Boron oxide (B 2 O 3 Silicon dioxide (SiO 2 The second glass composition may contain 1 to 20 parts by mol, or 5 to 15 parts by mol, based on 100 parts by mol of the total amount of the second glass composition. 2 O 3 ) may be included in an amount of 0.1 to 10 parts by mol, or 0.5 to 5 parts by mol, based on 100 parts by mol of the total amount of the second glass composition. When each component is included within the above content range as the second glass composition when forming the second paste for forming the upper layer, an external electrode having excellent contact with the internal electrode, corrosion resistance, and moisture resistance reliability can be manufactured.

[0140] At least one of the first paste for forming the lower layer and the second paste for forming the upper layer may further include a conductive metal, that is, either one of the first paste for forming the lower layer and the second paste for forming the upper layer may include a conductive metal, or both of the first paste for forming the lower layer and the second paste for forming the upper layer may include a conductive metal.

[0141] 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, such as copper (Cu) or a copper (Cu) alloy.

[0142] As an example, the conductive metal contained in the first paste for forming the lower layer may be contained in an amount of 80% by weight or more and 99% by weight or less based on the total amount of the first paste for forming the lower layer, and the conductive metal contained in the second paste for forming the upper layer may be contained in an amount of 80% by weight or more and 99% by weight or less based on the total amount of the second paste for forming the upper layer.

[0143] At least one of the first paste for forming the lower layer and the second paste for forming the upper layer may further include a binder, a solvent, a dispersant, a plasticizer, an oxide powder, and the like.

[0144] The binder may be, for example, ethyl cellulose, acrylic, or butyral, and the solvent may be, for example, an organic solvent such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, or toluene, or an aqueous solvent.

[0145] The first paste for forming the lower layer can be applied to the outer surface of the capacitor body 110 using various printing methods such as a dipping method and screen printing, an application method using a dispenser, a spraying method using a spray, etc. The first paste for forming the lower layer is applied to at least the third and fourth surfaces of the capacitor body 110, and may be selectively applied to a part of the first, second, fifth, or sixth surface on which the band portions of the first and second external electrodes are formed.

[0146] Sintering can be carried out at a temperature of 700° C. to 1000° C. for 0.1 to 3 hours.

[0147] Alternatively, a conductive resin layer may be formed by applying a paste for forming a conductive resin layer to the outer surface of the capacitor body 110 having the upper layers 20 and 40 formed on the lower layers 10 and 30 and then curing the paste.

[0148] The paste for forming the conductive resin layer may include a resin, and optionally a conductive metal or a non-conductive filler. The conductive metal and the resin are the same as those described above, and therefore will not be described again. The paste for forming the conductive resin layer may optionally include a binder, a solvent, a dispersant, a plasticizer, an oxide powder, etc. Examples of the binder include ethyl cellulose, acrylic, butyral, etc., and examples of the solvent include organic solvents such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, and toluene, or aqueous solvents.

[0149] As an example, the conductive resin layer may be formed by dipping the capacitor body 110 into a 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 using a screen printing method or a gravure printing method, or by applying the paste for forming the conductive resin layer on the surface of the capacitor body 110 and then curing it.

[0150] Next, a plating layer may be formed on the outside of the conductive resin layer.

[0151] For example, the plating layer can be formed by a plating method, and can also be formed by sputtering or electric deposition.

[0152] The above-mentioned embodiments will be described in more detail with reference to the following examples, which are merely for illustrative purposes and are not intended to limit the scope of the invention.

[0153] [Example] (Manufacturing multilayer ceramic capacitors) [Example 1] Barium titanate (BaTiO 3 After preparing a dielectric green sheet using the main component powder, a conductive paste layer containing nickel (Ni) was printed on the surface of the dielectric green sheet, and the dielectric green sheet (width x length x height = 3.2 mm x 2.5 mm x 2.5 mm) on which the conductive paste layer was formed was laminated and compressed to prepare a dielectric green sheet laminate. The dielectric green sheet laminate was subjected to a plasticization process in a nitrogen atmosphere at 400°C or less, and then sintered at a temperature of 1300°C or less and with a hydrogen concentration of 1.0% H 2 The capacitor body was manufactured by firing under the following conditions.

[0154] A first paste for forming a lower layer, which includes Cu and a first glass composition having the composition shown in Table 1 below, was applied to one surface of the capacitor body and sintered at 730°C for 1 hour to form a lower layer of an external electrode. At this time, the total amount of Cu and the first glass composition was 90 wt% and the first glass composition was 10 wt%. Next, a second paste for forming an upper layer, which includes Cu and a second glass composition having the composition shown in Table 1 below, was applied on the formed lower layer and sintered at 730°C for 1 hour to form an upper layer of an external electrode. At this time, the total amount of Cu and the second glass composition was 90 wt% and the second glass composition was 10 wt%. Next, a multilayer ceramic capacitor was manufactured through a process such as plating.

[0155] [Table 1]

[0156] [Comparative Example 1] A multilayer ceramic capacitor was manufactured in the same manner as in Example 1, except that a paste for forming an external electrode containing Cu and a glass composition having the composition shown in Table 2 below was applied to one surface of a capacitor body, and sintered at 730° C. for 1 hour to form an external electrode. At this time, the Cu content was 90 wt % and the glass composition content was 10 wt % based on the total amount of Cu and the glass composition.

[0157] [Table 2]

[0158] [Evaluation 1: SEM analysis] The multilayer ceramic capacitor manufactured in Example 1 was subjected to a SEM (scanning electron microscope) analysis, and the results are shown in FIG.

[0159] The SEM analysis was performed as follows. The multilayer ceramic capacitor 100 manufactured in Example 1 was immersed in an epoxy mixture and cured, and then polished using sand paper and a diamond suspension to obtain a cross-sectional sample having an LT surface so that the external electrodes could be observed. The obtained cross-sectional sample was measured using a scanning electron microscope (SEM). For example, the SEM was measured using a Tescan Vega3 under conditions of 20 kV, 0.2 nA, and an analysis magnification of 3k.

[0160] FIG. 5 is a SEM analysis image of the external electrodes of the multilayer ceramic capacitor according to Example 1. As shown in FIG.

[0161] Referring to FIG. 5, in the case of Example 1 according to an embodiment, it can be seen that the external electrodes are formed of a double layer of a lower layer and an upper layer on the cross section of the capacitor body.

[0162] [Evaluation 2: SEM-EDS analysis] The multilayer ceramic capacitor manufactured in Example 1 was subjected to SEM-EDS (scanning electron microscope-energy dispersive spectroscopy) analysis, and the results are shown in FIGS. 6a and 6b.

[0163] The SEM-EDS analysis was performed as follows. The multilayer ceramic capacitor 100 manufactured in Example 1 was immersed in an epoxy mixture and cured, and then polished using sand paper and a diamond suspension to obtain a cross-sectional sample having an LT surface so that the external electrodes could be observed. The obtained cross-sectional sample was measured using a scanning electron microscope (SEM). For example, the SEM was measured using a Tescan Vega3 under conditions of 20 kV, 0.2 nA, and an analysis magnification of 6005 times. Next, an EDS (energy dispersive spectroscopy) analysis was performed on the SEM image of the measured cross-sectional sample to confirm the content of each component present in the lower layer and upper layer of the external electrodes.

[0164] FIG. 6a is a cross-sectional SEM-EDS analysis image of an upper layer of an external electrode according to Example 1, and FIG. 6b is a cross-sectional SEM-EDS analysis image of a lower layer of an external electrode according to Example 1. As shown in FIG.

[0165] 6a and 6b, in the case of Example 1 according to one embodiment, the first glass included in the lower layer of the external electrode contains aluminum (Al) at 7.64 atomic %, and the second glass included in the upper layer of the external electrode contains aluminum (Al) at 16 atomic %.

[0166] [Evaluation 3: SEM analysis] The multilayer ceramic capacitors manufactured in Example 1 and Comparative Example 1 were subjected to SEM (scanning electron microscope) analysis to measure the thicknesses of the central and corner portions of the external electrodes. The results are shown in FIGS. 7a and 7b and Table 3 below.

[0167] The SEM analysis was performed in the same manner as in Evaluation 1. In the SEM image of the obtained external electrode, the midpoint of the length in the thickness direction (T-axis direction) of the multilayer ceramic capacitor was defined as center A, and the corner of the multilayer ceramic capacitor was defined as corner B.

[0168] 7A is a cross-sectional SEM-EDS analysis image of an external electrode of the multilayer ceramic capacitor according to Example 1, and FIG. 7B is a cross-sectional SEM-EDS analysis image of an external electrode of the multilayer ceramic capacitor according to Comparative Example 1. As shown in FIG.

[0169] [Table 3]

[0170] 7a and 7b, in Example 1 according to an embodiment, the thickness of the corners of the external electrodes is increased compared to Comparative Example 1.

[0171] [Evaluation 4: EPMA analysis] The multilayer ceramic capacitor manufactured in Example 1 was analyzed by EPMA (Electron Probe Microanalyzer), and the results are shown in FIG. 8 and Table 4 below.

[0172] The EPMA analysis was performed as follows. The multilayer ceramic capacitor 100 manufactured in Example 1 was immersed in an epoxy mixture and cured, and then polished using sand paper and diamond suspension to obtain a cross-sectional sample having an LT surface so that the external electrodes could be observed. The cross-sectional sample was subjected to EPMA (Electron Probe Microanalyzer) analysis at a voltage of 15 kV and a magnification of 10 kV. As a result of the measurement, the mapping of each element present in the lower and upper layers of the external electrodes and the content of each element were confirmed.

[0173] FIG. 8 is a cross-sectional EPMA analysis image of the external electrode of the multilayer ceramic capacitor according to Example 1.

[0174] [Table 4]

[0175] Referring to Table 4 and FIG. 8, in the case of Example 1, it can be seen that sodium (Na) and iron (Fe) are present as the second glass components contained in the upper layer of the external electrode.

[0176] Meanwhile, the small amount of sodium (Na) and iron (Fe) detected in the lower layer of the external electrode is due to sodium oxide (Na 2 O) and iron oxide (Fe 2 O 3 ) and some of the components are thought to have diffused into the lower layer.

[0177] [Evaluation 5: Moisture resistance reliability] The moisture resistance reliability of the multilayer ceramic capacitors manufactured in Example 1 and Comparative Example 1 was measured, and the results are shown in FIGS. 9a and 9b.

[0178] Specifically, ten multilayer ceramic capacitors each manufactured in Example 1 and Comparative Example 1 were prepared and mounted on a measurement board, and measured using ESPEC (PR-3J, 8585) equipment under conditions of 85°C, relative humidity (RH) 85%, 6.3V, and 24 hours.

[0179] FIG. 9a is a graph showing the moisture resistance reliability of the external electrodes according to Example 1, and FIG. 9b is a graph showing the moisture resistance reliability of the external electrodes according to Comparative Example 1. As shown in FIG.

[0180] 9a and 9b, in accordance with one embodiment, the external electrode is formed of a double layer, and the lower layer and the upper layer each contain different atomic % of Al. In this case, Example 1 has superior moisture resistance reliability compared to Comparative Example 1, in which the external electrode is formed of a single layer.

[0181] Although a preferred embodiment of the present invention has been described above, the present invention is not limited thereto, and can be embodied in various modified forms within the scope of the claims, the description of the invention, and the accompanying drawings, which of course also fall within the scope of the present invention. [Explanation of symbols]

[0182] 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 10: 1st lower layer 20: First upper layer 30:Second lower layer 40: 2nd upper layer

Claims

1. a capacitor body including a dielectric layer and an internal electrode layer; and an external electrode disposed outside the capacitor body; the external electrode includes a lower layer disposed on a cross section of the capacitor body to be electrically connected to at least one of the internal electrode layers, and an upper layer covering the lower layer and disposed on the lower layer; the bottom layer comprises a first glass; the top layer comprises a second glass; The first glass contains aluminum (Al) in an amount of more than 0 and not more than 8 atomic % based on the total amount of components of the first glass, The second glass contains aluminum (Al) in an amount of 10 atomic % or more and 20 atomic % or less based on a total amount of components of the second glass.

2. The multilayer ceramic capacitor according to claim 1 , wherein the aluminum (Al) contained in the second glass has an atomic ratio of more than 2 and not more than 100 relative to the aluminum (Al) contained in the first glass.

3. 2. The multilayer ceramic capacitor according to claim 1, wherein the second glass further contains lithium (Li), sodium (Na), iron (Fe), barium (Ba), calcium (Ca), zinc (Zn), boron (B), silicon (Si), tin (Sn), or a combination thereof.

4. The second glass contains silicon (Si), 4. The multilayer ceramic capacitor according to claim 3, wherein a total content of the aluminum (Al) and the silicon (Si) contained in the second glass is 20 atomic % or more and 50 atomic % or less with respect to a total amount of the components of the second glass.

5. 2. The multilayer ceramic capacitor according to claim 1, wherein the first glass further contains lithium (Li), sodium (Na), iron (Fe), barium (Ba), calcium (Ca), zinc (Zn), boron (B), silicon (Si), tin (Sn), or a combination thereof.

6. The first glass contains the barium (Ba) and the zinc (Zn), 6. The multilayer ceramic capacitor according to claim 5, wherein a total content of the barium (Ba) and zinc (Zn) contained in the first glass is 50 atomic % or more and 95 atomic % or less with respect to a total amount of the components of the first glass.

7. The first glass and the second glass further contain sodium (Na), 2. The multilayer ceramic capacitor according to claim 1, wherein the sodium (Na) contained in the second glass has an atomic ratio of more than 2 and not more than 100 relative to the sodium (Na) contained in the first glass.

8. The first glass and the second glass further contain iron (Fe), The multilayer ceramic capacitor according to claim 1 , wherein the iron (Fe) contained in the second glass has an atomic ratio of more than 2 and not more than 100 relative to the iron (Fe) contained in the first glass.

9. The multilayer ceramic capacitor of claim 1 , wherein at least one of the lower layer and the upper layer further comprises a conductive metal.

10. 10. The multilayer ceramic capacitor of claim 9, wherein the conductive metal comprises copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), an alloy thereof, or a combination thereof.

11. 2. The multilayer ceramic capacitor according to claim 1, wherein a middle point of the external electrode in a thickness direction of the multilayer ceramic capacitor is referred to as a center portion, and a corner point of the external electrode is referred to as a corner portion, and a thickness ratio of the corner portion to the center portion of the external electrode is 0.1 to 0.

5.

12. The multilayer ceramic capacitor according to claim 3 , wherein the second glass contains the lithium (Li).

13. The first glass further contains lithium (Li), The multilayer ceramic capacitor according to claim 12 , wherein the lithium (Li) contained in the second glass has an atomic ratio of more than 1 relative to the lithium (Li) contained in the first glass.

14. applying a first paste for forming a lower layer, the first paste including a first glass composition for forming a first glass, to one surface of the capacitor body including the dielectric layer and the internal electrode layer; sintering the first paste for forming the lower layer to form a lower layer of an external electrode; Applying a second paste for forming an upper layer, the second paste including a second glass composition for forming a second glass, on the lower layer of the external electrode; and sintering the second paste for forming the upper layer to form an upper layer of an external electrode; The first glass composition is made of aluminum oxide (Al ２ O ３ in an amount of more than 0 and not more than 8 molar parts per 100 molar parts of the first glass composition, The second glass composition is made of aluminum oxide (Al ２ O ３ ) in an amount of 10 parts by mol or more and 20 parts by mol or less relative to a total amount of 100 parts by mol of the second glass composition.

15. applying a first paste for forming a lower layer, the first paste including a first glass composition for forming a first glass, to one surface of the capacitor body including the dielectric layer and the internal electrode layer; applying a second paste for forming an upper layer, the second paste including a second glass composition for forming a second glass, on the first paste for forming a lower layer; and sintering the capacitor body on which the first paste for forming the lower layer and the second paste for forming the upper layer are applied to form an external electrode including a lower layer and an upper layer; The first glass composition is made of aluminum oxide (Al ２ O ３ in an amount of more than 0 and not more than 8 molar parts per 100 molar parts of the first glass composition, The second glass composition is made of aluminum oxide (Al ２ O ３ ) in an amount of 10 parts by mol or more and 20 parts by mol or less relative to a total amount of 100 parts by mol of the second glass composition.

16. The first glass composition contains barium oxide (BaO), calcium oxide (CaO), zinc oxide (ZnO), boron oxide (B ２ O ３ ), silicon dioxide (SiO ２ 16. The method for producing a multilayer ceramic capacitor according to claim 14 or 15, further comprising:

17. Relative to 100 parts by mole of the total amount of the first glass composition, The barium oxide (BaO) is contained in an amount of 10 parts by mol to 40 parts by mol, The calcium oxide (CaO) is contained in an amount of 1 part by mol or more and 20 parts by mol or less, The zinc oxide (ZnO) is contained in an amount of 10 parts by mol or more and 40 parts by mol or less, The boron oxide (B ２ O ３ ) is contained in an amount of 10 parts by mol or more and 40 parts by mol or more, The silicon dioxide (SiO ２ 17. The method for producing a multilayer ceramic capacitor according to claim 16, wherein the content of said component (I) is from 1 part by mol to 20 parts by mol.

18. The second glass composition is made of lithium oxide (Li ２ O, sodium oxide (Na ２ O), barium oxide (BaO), calcium oxide (CaO), zinc oxide (ZnO), boron oxide (B ２ O ３ ), silicon dioxide (SiO ２ ), iron oxide (Fe ２ O ３ 16. The method for producing a multilayer ceramic capacitor according to claim 14 or 15, further comprising:

19. Relative to 100 parts by mole of the second glass composition, The lithium oxide (Li ２ O) is contained in an amount of 1 part by mol or more and 20 parts by mol or less, The sodium oxide (Na ２ O) is contained in an amount of 1 part by mol or more and 20 parts by mol or less, The barium oxide (BaO) is contained in an amount of 10 parts by mol to 40 parts by mol, The calcium oxide (CaO) is contained in an amount of 1 part by mol or more and 20 parts by mol or less, The zinc oxide (ZnO) is contained in an amount of 1 part by mol to 20 parts by mol, The boron oxide (B ２ O ３ ) is contained in an amount of 10 parts by mol or more and 40 parts by mol or less, The silicon dioxide (SiO ２ ) is contained in an amount of 1 part by mol or more and 20 parts by mol or less, The iron oxide (Fe ２ O ３ 20. The method for producing a multilayer ceramic capacitor according to claim 18, wherein the content of the component (I) is 0.1 parts by mol or more and 10 parts by mol or less.

20. The method for manufacturing a multilayer ceramic capacitor according to claim 14 or 15, wherein at least one of the first paste for forming a lower layer and the second paste for forming an upper layer further includes a conductive metal.

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