Composite particle, multilayer ceramic capacitor, and method for manufacturing multilayer ceramic capacitor

Abstract

The present disclosure provides a composite particle, a multilayer ceramic capacitor, and a method for manufacturing the multilayer ceramic capacitor. The composite particle according to an embodiment of the present disclosure comprises: a conductive core; a conductive oxide layer disposed on the conductive core and including a metal oxide; and a coating layer disposed on the conductive oxide layer and including glass.

Description

Technical Field

[0001] This disclosure relates to a composite particle, a multilayer ceramic capacitor including the composite particle, and a method for manufacturing the multilayer ceramic capacitor. Background Technology

[0002] Electronic components using ceramic materials include capacitors, inductors, piezoelectric elements, varistors, and thermistors. Among these ceramic-based electronic components, multilayer ceramic capacitors (MLCCs) are used in a variety of electronic devices due to their small size, high capacitance, and ease of installation.

[0003] For example, a multilayer ceramic capacitor can be a chip capacitor used to be mounted on the substrate of various electronic products, including imaging devices such as liquid crystal displays (LCDs), plasma display panels (PDPs) and organic light-emitting diode (OLED) displays, computers, personal portable terminals and smartphones, to charge or discharge them.

[0004] Recently, with the miniaturization of electronic products, there is a need for ultra-miniaturized multilayer ceramic capacitors with ultra-high capacitance. To this end, multilayer ceramic capacitors with the following structure are being manufactured: the dielectric layer and internal electrode layer are thinned, and a greater number of dielectric and internal electrode layers are stacked. These ultra-miniature and ultra-high capacitance multilayer ceramic capacitors are currently being used in fields requiring high levels of reliability, such as electric vehicles; therefore, multilayer ceramic capacitors with high stability and high reliability are needed. Summary of the Invention

[0005] One aspect of this disclosure is to provide a composite particle with improved structural stability and dispersibility.

[0006] One aspect of this disclosure is to provide a multilayer ceramic capacitor with improved stability and capacitance characteristics.

[0007] However, the problems to be solved by this disclosure are not limited to those described above, and can be extended in various ways within the scope of the technical spirit included in this disclosure.

[0008] This disclosure provides a composite particle comprising: a conductive core; a conductive oxide layer disposed on the conductive core and comprising a metal oxide; and a coating disposed on the conductive oxide layer and comprising glass.

[0009] The conductive core may include copper.

[0010] The metal oxide may include copper oxide.

[0011] The glass may include at least one oxide selected from the group consisting of FeO, Fe2O3, Fe3O4, SnO, SnO2, CuO, Cu2O, MnO, Mn2O, Mn2O3, Mn3O4, Ag2O, GeO2, In2O3, CoO, TiO2, and P2O5.

[0012] Based on the total weight of the coating, the content of the oxide can range from 0.01 wt% to 20 wt%.

[0013] The thickness of the conductive oxide layer can be in the range of 1 nm to 20 nm.

[0014] The thickness of the coating can range from 1 nm to 50 nm.

[0015] The average particle size (D50) of the composite particles can be in the range of 0.1 μm to 1 μm.

[0016] This disclosure provides a multilayer ceramic capacitor, the multilayer ceramic capacitor comprising: a capacitor body including a dielectric layer and an inner electrode; and an outer electrode disposed on the outer side of the capacitor body and comprising composite particles, wherein the composite particles comprise: a conductive core; a coating disposed on the conductive core and comprising glass; and a conductive oxide layer disposed between the conductive core and the coating and comprising a metal oxide.

[0017] The inner electrodes may be configured as multiple, and the outer electrodes may include an electrode layer disposed on the surface of the capacitor body to be electrically connected to at least one of the inner electrodes; and the electrode layer may include the composite particles.

[0018] The internal electrode may include a first internal electrode and a second internal electrode alternately stacked in the stacking direction. The electrode layer is disposed on the surface of the capacitor body in the length direction. In a cross-section taken at the center of the multilayer ceramic capacitor in the width direction along the length direction and the stacking direction, the average area of ​​the glass included in the electrode layer may be 0.1 μm. 2 up to 5μm 2 Within the range, wherein the width direction and the length direction are perpendicular to the stacking direction and to each other.

[0019] The average area of ​​the glass can be measured by scanning electron microscopy (SEM) analysis of the electrode layer in the cross section.

[0020] The electrode layer may also include at least one selected from the group consisting of conductive particles, glass frit, and organic materials.

[0021] Based on the total weight of the composite particles and the conductive particles, the content of the composite particles can be in the range of 40wt% to 100wt%.

[0022] This disclosure provides a method for manufacturing a multilayer ceramic capacitor, the method comprising: manufacturing a capacitor body including a dielectric layer and an inner electrode; applying a paste for forming an electrode layer to a surface of the capacitor body; and sintering the paste to form the electrode layer of an outer electrode, wherein the paste comprises composite particles, or the paste comprises composite particles and a conductive metal, and when the paste comprises composite particles and a conductive metal, the content of the composite particles is in the range of 40 wt% to 100 wt% based on the total weight of the composite particles and the conductive metal.

[0023] In the method for manufacturing a multilayer ceramic capacitor, the paste may further include at least one selected from the group consisting of glass frit and organic materials.

[0024] According to embodiments of this disclosure, the structural stability of composite particles can be improved.

[0025] According to embodiments of this disclosure, the decrease in electrode layer density due to the melting of coarse glass can be suppressed, and the decrease in glass dispersion due to the agglomeration of fine glass flocs can be prevented. Therefore, the stability and reliability of the external electrode can be improved, and the capacitance characteristics of the multilayer ceramic capacitor can be enhanced. Attached Figure Description

[0026] Figure 1 This is a schematic cross-sectional view of the composite particles according to an embodiment.

[0027] Figure 2 These are transmission electron microscopy (TEM) images of the composite particles according to the embodiments.

[0028] Figures 3(a) and 3(b) are scanning electron microscope (SEM) images showing the density of the electrode layer based on the coating thickness of the composite particles in the electrode layer using the composite particles according to the embodiment.

[0029] Figure 4 This is a perspective view showing a multilayer ceramic capacitor according to an embodiment.

[0030] Figure 5 It is along Figure 4 A cross-sectional view of a multilayer ceramic capacitor taken by line I-I'.

[0031] Figure 6 It is along Figure 4 A cross-sectional view of a multilayer ceramic capacitor taken from line II-II'.

[0032] Figure 7The image is a SEM analysis image of the electrode layer of the external electrode of the multilayer ceramic capacitor in Example 3.

[0033] Figure 8 The image is a SEM analysis image of the external electrode of the multilayer ceramic capacitor based on Example 1.

[0034] Figure 9 The image is a SEM analysis image of the external electrode of the multilayer ceramic capacitor in Comparative Example 1.

[0035] Figure 10 The graph shows the change in capacitance relative to the content of composite particles in Examples 1 and 5 through 8, and in Comparative Example 1. Detailed Implementation

[0036] In the following detailed description, specific exemplary embodiments of this disclosure are shown and described by way of illustration only. The drawings and descriptions are intended to be illustrative rather than restrictive in nature. Throughout the specification, the same reference numerals denote the same elements. Furthermore, some constituent elements in the drawings may be enlarged, omitted, or shown schematically, and the dimensions of each constituent element do not perfectly reflect the actual dimensions.

[0037] The accompanying drawings are provided to help to readily understand the exemplary embodiments disclosed in this specification, and the technical spirit disclosed in this specification is not limited to the drawings. It will be understood that this disclosure includes all variations, equivalents and alternatives within the spirit and scope of this disclosure.

[0038] Terms including ordinal numbers (such as "first" and "second") are used to describe various constituent elements, but these constituent elements are not limited by the terms. These terms are only used to distinguish one constituent element from another.

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

[0040] In this disclosure, it will be understood that the terms “comprising,” “including,” and “having” are intended to indicate the presence of the features, quantities, steps, operations, constituent elements, components, or combinations thereof described in the specification, and do not preclude the possibility of the presence or addition of one or more other features, quantities, steps, operations, constituent elements, components, or combinations thereof. Therefore, unless expressly stated to the contrary, the words “comprising,” “including,” and “having” will be understood to imply the inclusion of the stated elements but not the exclusion of any other elements.

[0041] Furthermore, throughout the specification, the phrase "on a plane" refers to a view of the target portion as seen from above, and the phrase "on a cross section" refers to a cross section view obtained by vertically cutting the target portion as seen from the side.

[0042] Furthermore, throughout the specification, the term "connection" not only refers to the situation where two or more constituent elements are directly connected, but also to the situation where two or more constituent elements are indirectly connected through another constituent element. It can also refer to the situation where two or more constituent elements are physically or electrically connected. In addition, it can also refer to the situation where two or more constituent elements are actually integrated, although they are called by different names according to their location or function.

[0043] Figure 1 This is a schematic cross-sectional view of the composite particles according to an embodiment. Figure 1 A cross-sectional view showing a section cut through the center point of composite particle 50. Figure 2 These are transmission electron microscopy (TEM) images of the composite particles according to the embodiments. Figure 2 It is an image of the surface portion including the cross-section of composite particle 50.

[0044] The composite particle 50 of this disclosure can be interpreted as a single particle unit and can be distinguished from a composite structure in which conductive particles, glass frit, etc. (each of which is a single particle) are arranged adjacent to each other. Glass frit can refer to glass sheets, glass particles, or glass powder.

[0045] Reference Figure 1 and Figure 2 The composite particle 50 according to the embodiment may include: a conductive core 52; a conductive oxide layer 54 disposed on the conductive core 52; and a coating 56 disposed on the conductive oxide layer 54. For example, the conductive oxide layer 54 may be disposed on at least a portion of the conductive core 52. The coating 56 may be disposed on at least a portion of the conductive oxide layer 54.

[0046] The conductive core 52 may include copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), and their alloys. They may be used individually or in combination of two or more.

[0047] The conductive core 52 may have a spherical shape or a sheet shape.

[0048] The conductive core 52 may include copper. Therefore, the conductivity of the composite particles 50 can be improved, and structural damage during the process can be suppressed.

[0049] In this embodiment, the conductive oxide layer 54 may include a metal oxide. This improves the adhesion between the conductive core 52 and the coating 56. Consequently, it enhances the structural stability of the composite particles 50 during dispersion, pressurization, and / or heating processes.

[0050] The metal oxide may include an oxide of the metal included in the conductive core 52. For example, the conductive oxide layer 54 may be formed by oxidizing the metal of the conductive core 52.

[0051] According to an embodiment, the metal oxide may include copper oxide. Therefore, when the conductive core 52 contains copper, the adhesion stability between the conductive core 52 and the coating 56 can also be enhanced.

[0052] For example, copper oxides may include Cu2O.

[0053] The conductive oxide layer 54 can be directly disposed on the conductive core 52. Therefore, the chemical and structural stability of the conductive core 52 can be further enhanced, and the adhesion to the coating 56 can also be improved.

[0054] According to one embodiment, the thickness T1 of the conductive oxide layer 54 can be in the range of 1 nm to 20 nm. According to another embodiment, the thickness T1 of the conductive oxide layer 54 can be in the range of 3 nm to 10 nm. When the thickness T1 of the conductive oxide layer 54 is within the above range, the stability of the composite particles 50 can be sufficiently enhanced while suppressing the size increase of the composite particles 50. Therefore, the dispersibility and stability of the composite particles 50 can be further improved.

[0055] Multiple composite particles (50) can be configured. Figure 1 When multiple composite particles 50 are schematically shown, the thickness T1 of the conductive oxide layer 54 can be the average thickness of the conductive oxide layer 54 of each composite particle 50.

[0056] The thickness T1 of the conductive oxide layer 54 can be measured by TEM analysis. After the composite particles 50 are added to the epoxy resin mixture and thermocured, TEM sampling can be performed using FIB (Focused Ion Beam). By observing each of the composite particles 50 after TEM sampling using TEM, the thickness of the conductive oxide layer 54 of each composite particle 50 can be measured. The measured thicknesses can be averaged and evaluated as the aforementioned thickness T1.

[0057] According to an embodiment, coating 56 may include glass.

[0058] Glass can contain oxides. Therefore, glass can be supplied as corrosion-resistant glass.

[0059] For example, the oxide may include at least one selected from the group consisting of FeO, Fe2O3, Fe3O4, SnO, SnO2, CuO, Cu2O, MnO, Mn2O, Mn2O3, Mn3O4, Ag2O, GeO2, In2O3, CoO, TiO2 and P2O5.

[0060] The oxygen atoms of the metal and oxide in the conductive core 52 can react to form a metal oxide included in the conductive oxide layer 54.

[0061] A metal oxide can be formed between the conductive core 52 and the coating 56 according to the following reaction formula.

[0062] [Reaction Formula] 4Cu + 6Fe₂O₃ → 2Cu₂O + 4Fe₃O₄ According to an embodiment, the oxide content can be from 0.01 wt% to 20 wt% based on the total weight of the coating 56. In another embodiment, the oxide content can be from 1 wt% to 10 wt% based on the total weight of the coating 56. When the oxide content is within the above range, the conductive oxide layer 54 is sufficiently formed, thereby further enhancing the structural stability of the composite particles 50 and further suppressing the delamination of the coating 56 or the glass. For example, peeling of the coating 56, including glass, can be suppressed.

[0063] The coating 56 can be directly applied to the conductive oxide layer 54. Therefore, the bonding strength between the conductive core 52 and the coating 56 can be further improved through the conductive oxide layer 54.

[0064] According to one embodiment, the thickness T2 of the coating 56 can be in the range of 1 nm to 50 nm. According to another embodiment, the thickness T2 of the coating 56 can be in the range of 5 nm to 30 nm. When the thickness T2 of the coating 56 is within the above range, the size of the glass included in the composite particles 50 is relatively smaller than the size of the glass frit, thereby further improving the dispersion of the glass even when the glass melts. In addition, the density of the multilayer ceramic capacitor including the composite particles 50 can also be enhanced.

[0065] Multiple composite particles (50) can be configured. Figure 1 When multiple composite particles 50 are schematically shown, the thickness T2 of the coating 56 can be the average thickness of the coating 56 of each composite particle 50.

[0066] The thickness T2 of coating 56 can be measured by TEM analysis. After the composite particles 50 are added to the epoxy resin mixture and thermocured, TEM sampling can be performed using FIB (Focused Ion Beam). By observing each of the composite particles 50 after TEM sampling using TEM, the thickness of coating 56 of each composite particle 50 can be measured. The measured thicknesses can be averaged and evaluated as the aforementioned thickness T2.

[0067] Figures 3(a) and 3(b) are scanning electron microscope (SEM) images showing the density of the electrode layer based on the coating thickness of the composite particles in the electrode layer using the composite particles according to the embodiment.

[0068] Figures 3(a) and 3(b) show SEM images of a cross section (WT section) taken at the center of the electrode prepared using composite particles 50 along the width direction (W direction) and the stacking direction (T direction) perpendicular to the length direction (L-axis direction).

[0069] Figure 3(a) is the SEM analysis image when the thickness T2 of coating 56 is less than 50 nm, and Figure 3(b) is the SEM analysis image when the thickness T2 of coating 56 is greater than 50 nm.

[0070] Referring to Figures 3(a) and 3(b), the density of the electrode layer is relatively low when the thickness T2 of the coating 56 exceeds 50 nm, compared to the electrode layer density when the thickness T2 of the coating 56 is less than 50 nm.

[0071] According to an embodiment, the thickness T2 of the coating 56 may be uniform throughout the surface portion of the composite particle 50. For example, the thickness of the coating 56 at two points facing each other with respect to the center of the composite particle 50 may be substantially symmetrical (e.g., the thickness of the coating 56 at two points facing each other with respect to the center of the composite particle 50 may be substantially equal). The terms "uniform," "symmetrical," or "equal" may refer not only to precisely mechanical uniformity, symmetry, or equality, but may also include cases of "substantially uniform," "substantially symmetrical," or "substantially equal."

[0072] Therefore, it can also inhibit the agglomeration of glass and improve the dispersibility of composite particles 50.

[0073] According to an embodiment, the average particle size (D50) of the composite particles 50 can be in the range of 0.1 μm to 1 μm. According to another embodiment, the average particle size (D50) of the composite particles 50 can be in the range of 0.2 μm to 0.8 μm. When the average particle size (D50) of the composite particles 50 is within the above range, when the composite particles 50 are disposed as fine particles in a composition or structure including the composite particles 50, the dispersibility of the composite particles 50 can be further improved and the density of the electrode layer can also be increased.

[0074] As used herein, the terms “average particle size,” “D50,” or “average particle size (D50)” can refer to the size (particle size) at the point where the cumulative percentage in the cumulative size distribution reaches 50%. For example, the cumulative size distribution can be obtained by measuring the size of the longest axis of at least 100 composite particles in an SEM analysis image.

[0075] The following describes a method for manufacturing composite particles 50 according to another embodiment. For example, the composite particles 50 can be manufactured by a spray pyrolysis method.

[0076] In an embodiment, the core precursor and the glass precursor may be introduced into a solvent and mixed to prepare a solution.

[0077] The core precursor may include the metal described above included in the conductive core 52. Additionally, the glass precursor may include glass and the oxide described above included in the glass.

[0078] Core precursors and / or glass precursors may include nitrate-based precursors, acetate-based precursors, etc.

[0079] According to an embodiment, the solution can be atomized into microdroplets and introduced into a heating furnace.

[0080] In an embodiment, the composite particles 50 can be formed by drying, melting, and recrystallizing the particles formed by heating. For example, during heating, drying, melting, and recrystallization, a metal included in the core precursor can form a conductive core 52 due to relatively strong interatomic bonding forces, and a glass precursor having relatively weak interatomic bonding forces can form a coating 56 on the surface portion of the conductive core 52. For example, a metal oxide (e.g., Fe2O3) included in the glass precursor can cause oxidation of the metal (e.g., Cu) in the core precursor, thereby forming a conductive oxide layer 54 between the conductive core 52 and the glass-included coating 56. Therefore, the structural stability of the composite particles 50 can be improved, and delamination of the coating 56 can be suppressed.

[0081] By using the above-described spray pyrolysis method, composite particles 50 with a uniform thickness of coating 56 and conductive oxide layer 54 and a relatively small average particle size (D50) can be manufactured.

[0082] Below, we will refer to Figures 4 to 6 A multilayer ceramic capacitor according to another embodiment is described.

[0083] Figure 4 This is a perspective view of a multilayer ceramic capacitor according to another embodiment. Figure 5 It is along Figure 4 A cross-sectional view of a multilayer ceramic capacitor taken by line I-I'. Figure 6 It is along Figure 4 A cross-sectional view of a multilayer ceramic capacitor taken from line II-II'.

[0084] Reference Figures 4 to 6 The multilayer ceramic capacitor 100 may include 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, which are disposed at opposite ends of the capacitor body 110 in the longitudinal direction (L-axis direction).

[0085] Figures 4 to 6The L-axis, W-axis, and T-axis directions shown represent the length, width, and thickness directions of the capacitor body 110, respectively. Here, the thickness direction (T-axis) can be perpendicular to the wide surface (main surface) of the sheet assembly; for example, it can be used as the same concept as the stacking direction along which the stacked dielectric layers 111 are arranged. The length direction (L-axis) can be parallel to the wide surface (main surface) of the sheet assembly and substantially perpendicular to the thickness direction (T-axis); for example, the length direction (L-axis) can be the direction in which the first external electrode 131 and the second external electrode 132 are opposite each other. The width direction (W-axis) can be parallel to the wide surface (main surface) of the sheet assembly and substantially perpendicular to both the thickness direction (T-axis) and the length direction (L-axis), and the length of the sheet assembly in the length direction (L-axis) can be greater than the width of the sheet assembly in the width direction (W-axis).

[0086] For example, the capacitor body 110 may have a generally hexahedral shape.

[0087] For ease of description, the two surfaces of the capacitor body 110 that are opposite to each other in the thickness direction (T-axis direction) are defined as the first surface and the second surface; the two surfaces of the capacitor body 110 that are connected to the first surface and the second surface and are opposite to each other in the length direction (L-axis direction) are defined as the third surface and the fourth surface; and the two surfaces of the capacitor body 110 that are connected to the first surface and the second surface, and connected to the third surface and the fourth surface and are opposite to each other in the width direction (W-axis direction) are defined as the fifth surface and the sixth surface.

[0088] The first surface, which is the lower surface of the capacitor body 110, can be a mounting surface. For example, at least one of the first to sixth surfaces can be flat. For example, at least one of the first to sixth surfaces can be a surface with a convex central portion, and the corners that form the boundaries of each surface can be rounded.

[0089] The shape and size of the capacitor body 110 and the number of stacked dielectric layers 111 are not limited to the shape and size of the capacitor body 110 and the number of stacked dielectric layers 111 shown in the accompanying drawings of this embodiment.

[0090] The capacitor body 110 includes a dielectric layer 111 and internal electrodes 121 and 122. The capacitor body 110 may include a plurality of dielectric layers 111.

[0091] The internal electrodes 121 and 122 may include a first internal electrode 121 and a second internal electrode 122. The capacitor body 110 includes a plurality of dielectric layers 111 and a first internal electrode 121 and a second internal electrode 122, the first internal electrode 121 and the second internal electrode 122 being arranged alternately in the thickness direction (T-axis direction), and the dielectric layer 111 being located between the first internal electrode 121 and the second internal electrode 122.

[0092] The adjacent dielectric layers 111 of the capacitor body 110 can be integrated to such an extent that the boundaries between them are difficult to identify without the use of SEM.

[0093] The capacitor body 110 may include an effective region. The effective region may be a portion that contributes to the capacitance formation of the multilayer ceramic capacitor 100. For example, the effective region may be a region where a first inner electrode 121 and a second inner electrode 122 are stacked on top of each other along the thickness direction (T-axis direction).

[0094] The capacitor body 110 may also include a cover area and a side edge area.

[0095] The cover region is the edge portion in the thickness direction (T-axis direction) and can be disposed adjacent to the upper and lower surfaces of the effective region in the thickness direction (T-axis direction), respectively. For example, a single dielectric layer or two or more dielectric layers can be stacked on the upper and lower surfaces of the effective region, respectively, to form the cover region.

[0096] The side edge region is an edge portion in the width direction (W-axis direction) and can be disposed adjacent to two surfaces of the effective region that are opposite to each other in the width direction (W-axis direction) (i.e., the surfaces corresponding to the fifth and sixth surfaces). The side edge region can be formed by stacking dielectric green sheets and then firing the dielectric green sheets, wherein only a conductive paste layer is applied to a portion of the surface of the dielectric green sheets, and the conductive paste layer is not applied to the two side edges of the surface of the dielectric green sheets (the portions where the side edge regions will be formed).

[0097] The covered area and side edge area can prevent damage to the first inner electrode 121 and the second inner electrode 122 due to physical stress and / or chemical stress.

[0098] The dielectric layer 111 may include a material having a perovskite (ABO3) structure (e.g., a barium titanate-based compound) as the main component. For example, by using a barium titanate-based compound as the dielectric matrix, the dielectric properties of the multilayer ceramic capacitor 100 can be ensured.

[0099] Materials with a perovskite (ABO3) structure may include BaTiO3, BaZrO3, BaSnO3, CaTiO3, CaZrO3, CaSnO3, SrTiO3, SrZrO3, SrSnO3, etc. They can be used alone or in combination of two or more.

[0100] The dielectric layer 111 may also include secondary components.

[0101] Byproducts 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), etc. They can be used alone or in combination of two or more.

[0102] According to one embodiment, the average thickness (average dimension in the T-axis direction) of the dielectric layer 111 can be in the range of 1.0 μm to 8.0 μm. According to another embodiment, the average thickness (average dimension in the T-axis direction) of the dielectric layer 111 can be in the range of 2 μm to 6 μm. When the average thickness of the dielectric layer 111 is within the above range, the reliability of the multilayer ceramic capacitor 100 can be further enhanced.

[0103] For example, the average thickness of the dielectric layer 111 can be the arithmetic mean of the thickness of the dielectric layer 111 measured at 10 points (as reference points) spaced at predetermined intervals from the center point of the dielectric layer 111 in the length direction (L-axis direction) or width direction (W-axis direction) of the cross-sectional sample obtained as described above (e.g., SEM analysis images of the LT or WT cross-section). The interval between any two adjacent points among the 10 points can be adjusted according to the scale of the scanning electron microscope (SEM) image, for example, in the range of 1 μm to 100 μm, in the range of 1 μm to 50 μm, or in the range of 1 μm to 10 μm. In this case, all 10 points must be located within the dielectric layer 111, and if not all 10 points are located within the dielectric layer 111, the position of the reference point can be changed, or the interval between any two adjacent points among the 10 points can be adjusted.

[0104] The first inner electrode 121 and the second inner electrode 122 of the inner electrodes 121 and 122 may have different polarities. For example, the first inner electrode 121 and the second inner electrode 122 may be arranged alternately opposite each other along the T-axis, with the dielectric layer 111 between them. For example, one end of the first inner electrode 121 may be exposed through the third surface of the capacitor body 110, and one end of the second inner electrode 122 may be exposed through the fourth surface of the capacitor body 110.

[0105] The first inner electrode 121 and the second inner electrode 122 are electrically insulated from each other by a dielectric layer 111 disposed between them.

[0106] The end of the first inner electrode 121 exposed through the third surface of the capacitor body 110 can be electrically connected to the first outer electrode 131. Additionally, the end of the second inner electrode 122 exposed through the fourth surface of the capacitor body 110 can be electrically connected to the second outer electrode 132.

[0107] Both the first internal electrode 121 and the second internal electrode 122 may comprise a conductive metal. For example, the conductive metal may comprise metals such as Ni, Cu, Ag, Pd, or Au, or alloys thereof (e.g., Ag-Pd alloys).

[0108] The first inner electrode 121 and the second inner electrode 122 may comprise dielectric materials having the same composition as the ceramic material included in the dielectric layer 111.

[0109] The first inner electrode 121 and the second inner electrode 122 can be formed using a conductive paste comprising a conductive metal. For example, the conductive paste can be printed by screen printing or gravure printing.

[0110] According to the embodiment, the average thickness of the first inner electrode 121 and the average thickness of the second inner electrode 122 can be in the range of 0.1 μm to 2 μm. When the average thickness of the first inner electrode 121 and the average thickness of the second inner electrode 122 are within the above range, the resistance can be further reduced because the miniaturization and thinning of the multilayer ceramic capacitor 100 are achieved.

[0111] The average thickness of the first inner electrode 121 and the average thickness of the second inner electrode 122 can be measured by SEM analysis. The method for measuring the average thickness of the first inner electrode 121 and the average thickness of the second inner electrode 122 is basically the same as the method described above for measuring the average thickness of the dielectric layer 111, so repeated descriptions will be omitted.

[0112] The capacitor body 110 can be formed by firing a laminate in which multiple dielectric layers 111 and internal electrodes 121 and 122 are stacked in the thickness direction (T-axis direction).

[0113] Reference Figure 5The first external electrode 131 and the second external electrode 132 may have different polarities.

[0114] The first external electrode 131 can be electrically connected to the exposed portion of the first internal electrode 121. Additionally, the second external electrode 132 can be electrically connected to the exposed portion of the second internal electrode 122.

[0115] When a predetermined voltage is applied to the first external electrode 131 and the second external electrode 132, charge can accumulate between the first internal electrode 121 and the second internal electrode 122 facing each other. The electrostatic capacitance of the multilayer ceramic capacitor 100 is proportional to the stacked area of ​​the first internal electrode 121 and the second internal electrode 122 stacked together in the effective region along the stacking direction (T-axis direction).

[0116] The first external electrode 131 may include a first connection portion (not shown) disposed on the third surface of the capacitor body 110 and connected to the first internal electrode 121, and the second external electrode 132 may include a second connection portion (not shown) disposed on the fourth surface of the capacitor body 110 and connected to the second internal electrode 122. The first external electrode 131 may include a first strip portion (not shown) disposed at the corner where the third surface of the capacitor body 110 intersects with the first surface and the second surface and / or the fifth surface and the sixth surface, and the second external electrode 132 may include a second strip portion (not shown) disposed at the corner where the fourth surface of the capacitor body 110 intersects with the first surface and the second surface and / or the fifth surface and the sixth surface.

[0117] The first strip may extend from the first connecting portion to a portion of the first surface, a portion of the second surface, and / or a portion of the fifth surface and a portion of the sixth surface of the capacitor body 110. The second strip may extend from the second connecting portion to a portion of the first surface, a portion of the second surface, and / or a portion of the fifth surface and a portion of the sixth surface of the capacitor body 110. The first strip and the second strip can respectively improve the bonding strength between the first external electrode 131 and the second external electrode 132 and the capacitor body 110.

[0118] External electrodes 131 and 132 may include electrode layers 10 and 20 directly disposed on the surface of capacitor body 110.

[0119] The first external electrode 131 may include a first electrode layer 10, which is directly disposed on the surface of the capacitor body 110 (e.g., the third surface) and electrically connected to the first internal electrode 121. Additionally, the second external electrode 132 may include a second electrode layer 20, which is directly disposed on the surface of the capacitor body 110 (e.g., the fourth surface) and electrically connected to the second internal electrode 122.

[0120] Electrode layers 10 and 20 may include the aforementioned composite particles 50. As described above, the composite particles 50 may include: a conductive core 52; a conductive oxide layer 54 disposed on the conductive core 52 and comprising a metal oxide; and a coating 56 disposed on the conductive oxide layer 54 and comprising glass. By enhancing the dispersion of electrode layers 10 and 20 through the composite particles 50, the contact between the outer electrodes 131 and 132 and the inner electrodes 121 and 122 can be enhanced, and the capacitance characteristics of the multilayer ceramic capacitor 100 can be improved.

[0121] Electrode layers 10 and 20 can be formed by applying conductive paste to the capacitor body 110 and sintering the conductive paste.

[0122] According to an embodiment, in the composition of the conductive paste described above, composite particles 50 in which an oxide layer and glass are coated on the conductive core can be used instead of conductive particles and glass frit alone. Therefore, the decrease in electrode layer density due to the melting of coarse glass frit can be suppressed, and the decrease in glass dispersibility due to excessive agglomeration of fine glass frit can be prevented. Therefore, the structural stability of the external electrodes 131 and 132 can be improved, and the capacitance characteristics of the multilayer ceramic capacitor 100 can be enhanced.

[0123] Electrode layers 10 and 20 may include multiple glass layers.

[0124] According to an embodiment, the average area of ​​the glass included in electrode layers 10 and 20 can be 0.1 μm. 2 up to 5μm 2 Within the aforementioned range, when the average area of ​​the glass included in electrode layers 10 and 20 is within this range, the amount of coarse glass frit decreases, thereby further increasing the density of the electrode layers after sintering. Furthermore, the glass is sufficiently dispersed, thereby suppressing a decrease in the output or capacitance of the multilayer ceramic capacitor 100.

[0125] The average area of ​​the glass can be obtained by performing SEM analysis on a cross section (LT section) taken at the center of the multilayer ceramic capacitor 100 in the width direction (W-axis direction) along the length direction (L-axis direction) and the stacking direction (T-axis direction) perpendicular to the width direction.

[0126] The average area of ​​a glass can be the average of the individual areas of multiple glasses observed in a cross-section.

[0127] To measure the average area of ​​the glass, a multilayer ceramic capacitor 100 can be fixed with epoxy resin and polished with a polishing machine to expose the cross-section. Polishing can be performed to remove half of the width (W-axis) dimension of the multilayer ceramic capacitor 100. For the exposed cross-section, a rectangular region with a width of 300 μm and a length of 30 μm can be defined at the central portion of the electrode layers 10 and 20, and this rectangular region can be divided into six sub-rectangular regions, each with a width of 40 μm and a length of 30 μm. For each sub-rectangular region, a scanning electron microscope (SEM) image can be obtained, and the cross-sectional area of ​​each individual glass can be measured using an image analysis program (e.g., ImageJ software). The average area of ​​the glass can be obtained by averaging the cross-sectional areas of all the glass included in the six sub-rectangular regions.

[0128] Electrode layers 10 and 20 may also include at least one selected from the group consisting of conductive particles, glass frit, and organic materials.

[0129] The conductive particles may include the same type of material as the conductive core 52 described above. The glass frit may include the same type of material as the glass included in the coating 56 described above.

[0130] Organic materials may include binders, dispersants, plasticizers, etc. They may be used alone or in combination of two or more. There are no limitations on the materials that can be used as organic materials, as long as they are materials that can be selected in the art as needed.

[0131] As described above, the composite particles 50, including the conductive core 52, the conductive oxide layer 54, and the glass coating 56, can replace at least a portion of the conductive particles and the glass frit. Therefore, the density of the external electrodes 131 and 132 can be improved, and the dispersibility of the glass can be enhanced.

[0132] According to an embodiment, based on the total weight of the composite particles 50 and conductive particles included in electrode layers 10 and 20, the content of composite particles 50 can be in the range of 40 wt% to 100 wt%, and according to another embodiment, it can be in the range of 60 wt% to 100 wt%. When the content of composite particles 50 is within the above range, the glass in electrode layers 10 and 20 can be sufficiently dispersed, and the density of external electrodes 131 and 132 can be further improved. Therefore, the capacitive characteristics of the multilayer ceramic capacitor 100 can be further enhanced.

[0133] According to an embodiment, the external electrodes 131 and 132 may further include plating layers 30 and 40 respectively disposed on electrode layers 10 and 20.

[0134] Optionally, the external electrodes 131 and 132 may also include a conductive resin layer (not shown) disposed between the electrode layers 10 and 20 and the plating layers 30 and 40.

[0135] The conductive resin layer may extend to the first and second surfaces and / or the fifth and sixth surfaces of the capacitor body 110. In this case, the length of the region (i.e., the strip portion) in which the conductive resin layer is arranged to extend to the first and second surfaces and / or the fifth and sixth surfaces of the capacitor body 110 may be greater than the length of the region (i.e., the strip portion) in which the electrode layers 10 and 20 are arranged to extend to the first and second surfaces and / or the fifth and sixth surfaces of the capacitor body 110. For example, the conductive resin layer may completely cover the electrode layers 10 and 20.

[0136] The conductive resin layer may include resin and conductive metal.

[0137] There are no particular limitations on the resin included in the conductive resin layer, as long as it has adhesive and shock-absorbing properties and can be mixed with conductive metal powder to form a paste. For example, the resin may include phenolic resin, acrylic resin, silicone resin, epoxy resin or polyimide resin.

[0138] The conductive metal included in the conductive resin layer can be electrically connected to the inner electrodes 121 and 122 or the electrode layers 10 and 20.

[0139] Conductive metals can have spherical shapes, sheet shapes, or combinations thereof. For example, a conductive metal can have only a sheet shape or only a spherical shape, or it can be a mixture of sheet and spherical shapes.

[0140] Spherical shapes can also include shapes that are not perfect spheres, such as shapes with a length ratio (major axis / minor axis) of less than or equal to 1.45. Sheet shapes refer to flat and elongated shapes, and there are no particular restrictions; for example, the length ratio (major axis / minor axis) can be greater than or equal to 1.95.

[0141] The external electrodes 131 and 132 may also include plating layers 30 and 40 arranged to cover the aforementioned conductive resin layer.

[0142] The plating layers 30 and 40 may include a first plating layer 30 disposed on the first electrode layer 10 and a second plating layer 40 disposed on the second electrode layer 20.

[0143] Coatings 30 and 40 may include nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), lead (Pb), and their alloys. They may be used alone or in combination of two or more.

[0144] Both plating layers 30 and 40 can be nickel (Ni) plating layers or tin (Sn) plating layers. For example, plating layers 30 and 40 can both include a configuration in which nickel (Ni) plating layers and tin (Sn) plating layers are stacked sequentially, or a configuration in which tin (Sn) plating layers, nickel (Ni) plating layers, and tin (Sn) plating layers are stacked sequentially. For example, plating layers 30 and 40 can both include multiple nickel (Ni) plating layers and / or multiple tin (Sn) plating layers.

[0145] The mounting capability, structural reliability, resistance to external shocks, heat resistance and equivalent series resistance (ESR) of the multilayer ceramic capacitor 100 on the substrate can be improved by coatings 30 and 40.

[0146] The following describes a method for manufacturing a multilayer ceramic capacitor 100 according to another embodiment.

[0147] A method for manufacturing a multilayer ceramic capacitor 100 may include the following steps: manufacturing a capacitor body 110 including a dielectric layer 111 and inner electrodes 121 and 122; and forming outer electrodes 131 and 132 on the outer side of the capacitor body 110.

[0148] In the manufacturing process of capacitor body 110, dielectric paste that forms dielectric layer 111 after firing and conductive paste that forms internal electrodes 121 and 122 after firing can be prepared.

[0149] Dielectric powders can be uniformly mixed using wet mixing and dried, then heat-treated under predetermined conditions to obtain calcined powders. Organic or aqueous carriers can be added to the calcined powders, which can then be heated and mixed to prepare dielectric pastes.

[0150] The dielectric paste obtained above can be formed into a dielectric sheet using techniques such as the doctor blade method. For example, the dielectric paste may include additives selected from various dispersants, plasticizers, binders, by-product compounds, and / or glass.

[0151] Conductive paste for internal electrodes can be prepared by mixing conductive powder made from conductive metals or their alloys with a binder or solvent.

[0152] The conductive paste used for the internal electrode may contain indium (In).

[0153] The conductive paste used for the internal electrode may include ceramic powder (e.g., barium titanate-based ceramic powder) as a comaterial. The comaterial can inhibit the sintering of the conductive powder during the sintering process.

[0154] Conductive paste for the internal electrodes can be applied to the surface of the dielectric sheet in a predetermined pattern using various printing methods such as screen printing or transfer printing. Then, multiple layers of dielectric sheets with the internal electrode pattern formed thereon can be stacked, and the multiple layers of dielectric sheets are pressed in the stacking direction to obtain a dielectric sheet laminate. Dielectric sheets without internal electrode patterns can also be stacked, such that the dielectric sheets without internal electrode patterns are respectively disposed on the upper and lower surfaces of the dielectric sheet laminate in the stacking direction.

[0155] Alternatively, the dielectric green sheet laminate can be cut to a predetermined size by cutting or the like.

[0156] If necessary, the dielectric green sheet laminate can be cured and dried to remove plasticizers, etc., and after curing and drying, the dielectric green sheet laminate can be tumble polished using a horizontal centrifugal tumbler or similar device. During tumble polishing, the dielectric green sheet laminate, along with the dielectric and polishing fluid, can be placed in a tumbler container, and rotational motion or vibration can be applied to the tumbler container to polish unwanted parts (such as burrs generated during cutting). For example, after tumble polishing, the dielectric green sheet laminate can be cleaned with a cleaning solution such as water and dried.

[0157] The dielectric film laminate can be subjected to adhesive removal and firing processes to obtain the capacitor body 110.

[0158] The conditions for adhesive removal processing can be appropriately adjusted according to the main component composition of the dielectric layer and / or the main component composition of the internal electrode. For example, the heating rate during adhesive removal processing can be in the range of 5°C / hour to 300°C / hour, the temperature can be maintained in the range of 180°C to 400°C, and the temperature holding time can be in the range of 0.5 hours to 24 hours. The atmosphere for adhesive removal processing can be an air atmosphere or a reducing atmosphere.

[0159] The firing conditions can be appropriately adjusted according to the main composition of the dielectric layer and / or the main composition of the internal electrode. For example, the firing temperature can be in the range of 1200°C to 1350°C, or in the range of 1220°C to 1300°C, and the firing time can be in the range of 0.5 hours to 8 hours, or in the range of 1 hour to 3 hours. The firing atmosphere can be a reducing atmosphere, such as a humidified atmosphere of a mixture of nitrogen (N2) and hydrogen (H2). When the internal electrodes 121 and 122 comprise nickel (Ni) or a nickel (Ni) alloy, the oxygen partial pressure in the firing atmosphere can be 1.0 × 10⁻⁶. -14 MPa to 1.0×10 -10 Within the range of MPa.

[0160] After firing, annealing can be performed as needed. Annealing is a process used to re-oxidize the dielectric layer, and it can be performed if firing is carried out in a reducing atmosphere. The conditions of the annealing process can also be appropriately adjusted according to the main composition of the dielectric layer. For example, the temperature during annealing can be in the range of 950°C to 1150°C, the annealing time can be greater than 0 hours and less than or equal to 20 hours, and the heating rate can be in the range of 50°C / hour to 500°C / hour. The annealing atmosphere can be a humidified nitrogen (N2) atmosphere, and the oxygen partial pressure can be 1.0 × 10⁻⁶. -9 MPa to 1.0×10 -5 Within the range of MPa.

[0161] In adhesive removal, firing, or annealing processes, for example, a wetting agent can be used to humidify nitrogen, mixed gases, etc., in which case the temperature of the wetting agent can be in the range of 5°C to 75°C. Adhesive removal, firing, and annealing processes can be performed continuously or independently.

[0162] Optionally, surface treatments (such as sandblasting, laser irradiation, or tumble polishing) can be performed on the third and fourth surfaces of the obtained capacitor body 110. By performing such surface treatments, the ends of the first inner electrode 121 and the second inner electrode 122 can be exposed on the third and fourth surfaces of the capacitor body 110, respectively. This improves the electrical connection between the first outer electrode 131 and the first inner electrode 121, as well as the electrical connection between the second outer electrode 132 and the second inner electrode 122, and facilitates the formation of alloy portions.

[0163] A paste for forming electrode layers can be applied to the outer surface of the capacitor body 110 and then sintered to form electrode layers 10 and 20, thereby preparing outer electrodes 131 and 132.

[0164] The paste used to form the electrode layers may include the aforementioned composite particles 50, or may include the aforementioned composite particles 50 and a conductive metal. Therefore, the glass dispersion in the electrode layers 10 and 20 is enhanced, thereby improving the contact between the inner electrodes 121 and 122 and the outer electrodes 131 and 132, and enhancing the capacitance characteristics of the multilayer ceramic capacitor 100.

[0165] According to an embodiment, the content of composite particles 50 can be in the range of 40 wt% to 100 wt% based on the total weight of the composite particles 50 and the conductive metal, and in another embodiment, it can be in the range of 60 wt% to 100 wt%. When the content of composite particles 50 is within the above range, the glass within the electrode layers 10 and 20 can be sufficiently dispersed after sintering, and the density of the electrode layers can also be improved. Therefore, the capacitance characteristics of the multilayer ceramic capacitor 100 can be further enhanced.

[0166] The paste used to form the electrode layer may also include binders, solvents, dispersants, plasticizers, oxide powders, etc.

[0167] For the adhesive, for example, ethyl cellulose resin, acrylic resin, butyral resin, etc. can be used, and for the solvent, for example, organic solvents such as terpineol, butyl carbitol, ethanol, methyl ethyl ketone, acetone or toluene can be used, or aqueous solvents can be used.

[0168] Methods for applying a paste for forming an electrode layer to the outer surface of the capacitor body 110 may include dipping, various printing methods such as screen printing, coating methods using, for example, a dispenser, or spraying methods using a sprayer. The paste for forming the electrode layer may be applied to at least the third and fourth surfaces of the capacitor body 110, and optionally, may also be applied to portions of the first, second, fifth, and / or sixth surfaces where the first and second external electrodes will form.

[0169] Sintering can be performed at temperatures ranging from 400°C to 860°C. When sintering is performed within this temperature range, nickel oxide (NiO) can be easily reduced to form a Cu-Ni alloy. The formation of the Cu-Ni alloy enhances the connection between the external and internal electrodes, improves capacitance distribution, and reduces ESR.

[0170] Next, optionally, a paste for forming a conductive resin layer may be applied to the outer surface of the capacitor body 110 on which the electrode layers 10 and 20 have been formed, and then cured to form a conductive resin layer.

[0171] The paste used to form the conductive resin layer may include a resin and optionally a conductive metal or a non-conductive filler. The descriptions of the conductive metal and resin are the same as described above, and therefore, repeated descriptions will be omitted. Alternatively, the paste used to form the conductive resin layer may include an adhesive, solvent, dispersant, plasticizer, oxide powder, etc. For the adhesive, for example, ethyl cellulose resin, acrylic resin, butyral resin, etc., may be used, and for the solvent, for example, organic solvents such as terpineol, butyl carbitol, ethanol, methyl ethyl ketone, acetone, or toluene may be used, or an aqueous solvent may be used.

[0172] For example, a method for forming a conductive resin layer may include: immersing the capacitor body 110 in a paste for forming a conductive resin layer and then curing it; printing the paste for forming a conductive resin layer on the surface of the capacitor body 110 using a screen printing method, gravure printing method, etc., and then curing it; or coating the surface of the capacitor body 110 with a paste for forming a conductive resin layer and then curing it.

[0173] Coatings 30 and 40 can be formed on the outer side of the conductive resin layer.

[0174] Coatings 30 and 40 can be formed by plating, sputtering or electrodeposition.

[0175] Specific examples of this disclosure are presented below. However, these examples are for illustrative purposes only and should not be construed as limiting the scope of this disclosure.

[0176] Experimental Example 1 Examples 1 to 4 (Preparation of composite particles) The solution is prepared by adding copper nitrate (e.g., Cu(NO3)2) as a copper precursor and barium nitrate (e.g., Ba(NO3)2), calcium nitrate (e.g., Ca(NO3)2), aluminum nitrate (e.g., Al(NO3)3), zinc nitrate (e.g., Zn(NO3)2), boric acid, and tetraethoxysilane (TEOS) as glass precursors to 50 mL of distilled water and mixing them. The weight ratio of the copper precursor to the glass precursor is adjusted to 95:5.

[0177] The prepared solution was introduced into an ultrasonic droplet generator and sprayed as fine droplets into a furnace maintained at 900°C. In this case, an argon mixture (Ar:H2, volume ratio 9:1) was introduced as a carrier gas at a flow rate of 5 L / min. The fine droplets were sprayed, dried, melted, and recrystallized to prepare first composite particles having an average particle size (D50) of 0.1 μm to 1 μm and including a coating comprising glass with a thickness of 1 nm to 50 nm.

[0178] The average particle size (D50) and coating thickness can be measured by methods (e.g., TEM analysis) described in specific embodiments of this disclosure.

[0179] The weight ratio of copper precursor to glass precursor was changed to 90:10, 85:15 and 80:20, respectively, to prepare the second, third and fourth composite particles.

[0180] (Preparation of multilayer ceramic capacitors) The dielectric green sheet laminate (length × width × height = 3.2 mm × 2.5 mm × 2.5 mm) was prepared as follows: A dielectric green sheet was prepared using barium titanate (BaTiO3) as the main component powder. A conductive paste layer containing nickel (Ni) was then printed onto the surface of the dielectric green sheet. The dielectric green sheets with the conductive paste layer formed thereon were stacked and pressed. The dielectric green sheet laminate was calcined in a nitrogen atmosphere at a temperature of 400°C or lower, followed by firing at a firing temperature of 1300°C or lower with a hydrogen (H2) concentration of less than or equal to 1.0%, thereby preparing the capacitor body.

[0181] A paste for forming the electrode layer is prepared, comprising 80 wt% composite particles, 15 wt% binder, 1 wt% dispersant, and 4 wt% solvent. The paste for forming the electrode layer is applied to the outer surface of the capacitor body and dried, then sintered at approximately 800°C to form the electrode layer of the outer electrode.

[0182] The first composite particle described above is used as the composite particle in Example 1. The second composite particle described above is used as the composite particle in Example 2. The third composite particle described above is used as the composite particle in Example 3. The fourth composite particle described above is used as the composite particle in Example 4.

[0183] A multilayer ceramic capacitor is fabricated by sequentially forming a nickel (Ni) plating layer and a tin (Sn) plating layer on the surface of the electrode layer to form an external electrode.

[0184] Comparison Example 1 The multilayer ceramic capacitor was prepared in the same manner as in Example 1, except that a paste for forming the electrode layer consisting of 70 wt% copper (Cu), 10 wt% glass frit, 15% binder, 1 wt% dispersant and 4 wt% solvent was used instead of a paste for forming the electrode layer containing composite particles.

[0185] Compare Example 2 to Compare Example 4 Except that the glass frit content was changed to 15 wt% (Comparative Example 2), 20 wt% (Comparative Example 3), and 25 wt% (Comparative Example 4) based on the total weight of the paste used to form the electrode layer, and the copper content was reduced accordingly by increasing the amount of glass frit (e.g., the copper content was changed to 65 wt% (Comparative Example 2), 60 wt% (Comparative Example 3), and 55 wt% (Comparative Example 4)). The multilayer ceramic capacitor was prepared in the same manner as in Comparative Example 1.

[0186] Evaluation - Measurement of the average area of ​​glass in the electrode layer The multilayer ceramic capacitors according to Examples 1 to 4 and Comparative Examples 1 to 4 are placed horizontally, and the outer periphery of each multilayer ceramic capacitor is fixed with epoxy resin.

[0187] The multilayer ceramic capacitor is polished using a polishing machine to expose a cross-section taken at the center of the multilayer ceramic capacitor in the width direction (W-axis direction) along the length direction (L-axis direction) perpendicular to the width direction and the stacking direction (T-axis direction).

[0188] For the exposed cross section, a rectangular region with a measured width (dimension in the W-axis direction) of 300 μm and a length (dimension in the L-axis direction) of 30 μm is set at the central portion of each of the electrode layers 10 and 20, and this rectangular region is divided into six sub-rectangular regions, each with a width (dimension in the W-axis direction) of 40 μm and a length (dimension in the L-axis direction) of 30 μm.

[0189] Perform SEM image analysis on each of the six sub-rectangular regions to obtain six SEM analysis images.

[0190] The particle analysis function of ImageJ (an image analysis program) is used to measure the area of ​​a single piece of glass included in an SEM analysis image.

[0191] The average area of ​​the glass is obtained by averaging the areas of all the glass within the six sub-rectangular regions.

[0192] Alternatively, the diameter can be obtained by assuming the shape of each individual glass is circular and then converting it.

[0193] The average diameter is obtained by averaging the converted diameters of all the glass panes included in the six sub-rectangular regions.

[0194] The composition of the electrode layer of the external electrode, as well as the average area and average diameter of the glass included in the electrode layer, are shown in Table 1 below.

[0195] (Table 1)

[0196] Figure 7 The image is a SEM analysis image of the electrode layer of the external electrode of the multilayer ceramic capacitor in Example 3.

[0197] Refer to Table 1 and Figure 7 Compared with Comparative Examples 1 to 4, which respectively introduced different amounts of copper particles and glass frit, the average area and average diameter of the glass in Examples 1 to 4, which included composite particles (including a conductive core, a conductive oxide layer and a glass coating), were relatively small, thereby improving the density of the electrode layer and the dispersion of the glass.

[0198] Figure 8 and Figure 9 The images shown are SEM analysis images of the external electrodes of the multilayer ceramic capacitors according to Example 1 and Comparative Example 1, respectively.

[0199] Reference Figure 8 and Figure 9 Compared to Comparative Example 1 which uses copper particles and glass frit, Example 1 using the first composite particles reduces the size of the glass (e.g., the average area and average diameter of the glass) and improves the dispersibility of the glass and the density of the electrode layer.

[0200] Experimental Example 2 Example 5 The multilayer ceramic capacitor was prepared in the same manner as in Example 1, except that a paste for forming the electrode layer was used, comprising 14 wt% first composite particles, 56 wt% copper (Cu), 10 wt% glass frit, and 20 wt% organic materials (e.g., 15 wt% binder, 1 wt% dispersant, and 4 wt% solvent).

[0201] Examples 6 to 8 The multilayer ceramic capacitor was prepared in the same manner as in Example 5, except that the content of the first composite particles was changed to 28 wt% (Example 6), 42 wt% (Example 7), and 56 wt% (Example 8) respectively based on the total weight of the paste used to form the electrode layer, and the copper content was changed to 42 wt% (Example 6), 28 wt% (Example 7), and 14 wt% (Example 8) respectively.

[0202] Evaluation - Capacitance Measurement A rated voltage was applied to the multilayer ceramic capacitors of Examples 1 and 5 through 8, as well as Comparative Example 1, to measure capacitance.

[0203] Specifically, the capacitance was measured using an Agilent 4268A available from HP / Agilent at a frequency of 1 kHz and a voltage of 1 V.

[0204] The measurement results are evaluated as follows: ○: The capacitance distribution falls within the range of 1.62μF to 2.37μF.

[0205] △: The capacitance distribution overlaps with the range of 1.3μF or greater and less than 1.61μF.

[0206] X: The capacitance distribution falls within the range of less than 1.3μF.

[0207] The results of the composite particle content and capacitance evaluation based on the total weight of the composite particles and copper are shown in Table 2 below.

[0208] (Table 2)

[0209] Figure 10 This is a graph showing the change in capacitance relative to Examples 1 and 5 through 8, and the content of composite particles based on the total weight of composite particles and copper in Comparative Example 1. See Table 2 and... Figure 10 In Examples 1 and 6 to 8, where the content of composite particles based on the total weight of composite particles and copper is 40 wt% to 100 wt%, the composite particles are sufficiently dispersed within the electrode layer, thereby relatively enhancing the capacitance characteristics of the multilayer ceramic capacitor.

[0210] Compared to other examples (e.g., Examples 1 and Examples 6 to 8), in Example 5, where the content of composite particles based on the total weight of composite particles and copper is less than 40 wt% (e.g., the content of composite particles is 20 wt%), the glass dispersion within the electrode layer is relatively reduced, thereby degrading the capacitance characteristics of the multilayer ceramic capacitor.

[0211] Compared to Example 1 and Examples 5 through 8, in Comparative Example 1 where composite particles were not used, the capacitance characteristics of the multilayer ceramic capacitor deteriorated.

[0212] While this disclosure has been described in conjunction with exemplary embodiments now considered to be practical, it should be understood that this disclosure is not limited to the disclosed exemplary embodiments. Rather, this disclosure is intended to cover various variations and equivalents included within the spirit and scope of the appended claims.

[0213] <Explanation of reference numerals in the attached figures> 10: First electrode layer 20: Second electrode layer 30: First coating 40: Second coating 50: Composite particles 52: Conductive core 54: Conductive oxide layer 56: Coating 100: Multilayer ceramic capacitor 110: Capacitor body 111: Dielectric layer 121: First internal electrode 122: Second internal electrode 131: First external electrode 132: Second external electrode.

Claims

1. A composite particle, comprising: Conductive core; A conductive oxide layer is disposed on the conductive core and includes a metal oxide; as well as A coating is disposed on the conductive oxide layer and includes glass.

2. The composite particles according to claim 1, wherein: The conductive core comprises copper.

3. The composite particles according to claim 1, wherein: The metal oxide includes copper oxide.

4. The composite particles according to claim 1, wherein: The glass comprises at least one oxide selected from the group consisting of FeO, Fe2O3, Fe3O4, SnO, SnO2, CuO, Cu2O, MnO, Mn2O, Mn2O3, Mn3O4, Ag2O, GeO2, In2O3, CoO, TiO2, and P2O5.

5. The composite particles according to claim 4, wherein: Based on the total weight of the coating, the content of the oxide is in the range of 0.01 wt% to 20 wt%.

6. The composite particles according to claim 1, wherein: The thickness of the conductive oxide layer is in the range of 1 nm to 20 nm.

7. The composite particles according to claim 1, wherein: The thickness of the coating is in the range of 1 nm to 50 nm.

8. The composite particles according to claim 1, wherein the average particle size D50 of the composite particles is in the range of 0.1 μm to 1 μm.

9. A multilayer ceramic capacitor, comprising: The capacitor body includes a dielectric layer and internal electrodes; as well as The external electrode is disposed on the outer side of the capacitor body and comprises composite particles. The composite particles include: a conductive core; a coating disposed on the conductive core and comprising glass; and a conductive oxide layer disposed between the conductive core and the coating and comprising metal oxide.

10. The multilayer ceramic capacitor according to claim 9, wherein, The inner electrodes are configured as a plurality of ones, and the outer electrodes include an electrode layer disposed on the surface of the capacitor body to be electrically connected to the inner electrodes; and The electrode layer includes the composite particles.

11. The multilayer ceramic capacitor according to claim 10, wherein, The internal electrode comprises a first internal electrode and a second internal electrode alternately stacked in the stacking direction. The electrode layer is disposed on the surface of the capacitor body in the length direction. In a cross-section taken at the center of the multilayer ceramic capacitor in the width direction along the length direction and the stacking direction, the average area of ​​the glass included in the electrode layer is 0.1 μm. 2 up to 5μm 2 Within the range, wherein the width direction and the length direction are perpendicular to the stacking direction and to each other.

12. The multilayer ceramic capacitor according to claim 11, wherein: The average area of ​​the glass is measured by scanning electron microscopy analysis of the electrode layer in the cross-section.

13. The multilayer ceramic capacitor according to claim 10, wherein: The electrode layer further includes at least one selected from the group consisting of conductive particles, glass frit, and organic materials.

14. The multilayer ceramic capacitor according to claim 13, wherein: Based on the total weight of the composite particles and the conductive particles, the content of the composite particles is in the range of 40wt% to 100wt%.

15. A method for manufacturing a multilayer ceramic capacitor, the method comprising: Manufacturing a capacitor body including a dielectric layer and internal electrodes; A paste for forming the electrode layer is applied to the surface of the capacitor body; as well as The paste is sintered to form the electrode layer of the outer electrode, wherein, The paste comprises composite particles, or the paste comprises composite particles and conductive metal, and When the paste comprises composite particles and conductive metal, the content of the composite particles is in the range of 40 wt% to 100 wt% based on the total weight of the composite particles and the conductive metal.

16. The method of claim 15, wherein: The paste also includes at least one selected from the group consisting of glass frit and organic materials.

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