Multilayer ceramic capacitor and method of manufacturing the same

Abstract

An aspect of the present disclosure may provide a multilayer ceramic capacitor having excellent reliability and withstand voltage characteristics. According to another aspect of the present invention, there is provided a method of manufacturing the multilayer ceramic capacitor.SOLUTION: According to an aspect of the present disclosure, there is provided a multilayer ceramic capacitor including a capacitor body including a dielectric layer and an internal electrode layer, and an external electrode disposed on an outer surface of the capacitor body, wherein the dielectric layer includes a plurality of dielectric grains, at least one of the plurality of dielectric grains includes black spots, the number of the black spots is 4 or more and 16 or less per a cross-sectional area of 1 μm * 1 μm in the dielectric layer, and the black spots include a Si element and do not include at least two elements selected from Ba, Ti, and O, and a method of manufacturing the same.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a multilayer ceramic capacitor and a method for manufacturing the same. [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, having high capacitance, and being easy to mount, making them suitable for use in a variety of electronic devices.

[0003] For example, multilayer ceramic capacitors (MLCCs) can be used as chip capacitors that are 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, and serve to charge or discharge electricity.

[0004] Meanwhile, barium titanate, a piezoelectric and photoelectric material, is now being used as the main material for MLCCs, and research is underway to improve its reliability. Summary of the Invention [Problem to be solved by the invention]

[0005] One embodiment provides a multilayer ceramic capacitor with excellent reliability and voltage resistance characteristics.

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

[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 the outside of the capacitor body; wherein the dielectric layer includes a plurality of dielectric crystal grains, at least one of the plurality of dielectric crystal grains includes black dots, the number of the black dots being 4 to 16 per cross-sectional area of ​​1 μm × 1 μm in the dielectric layer, and the black dots include Si element but do not include at least two elements selected from Ba, Ti, and O.

[0008] The size of the black dots measured on a line drawn with the major axis of the dielectric crystal grain as a reference may be 5 nm or more and 40 nm or less.

[0009] The dielectric layer may further include a black spot peripheral region defined as a region extending from the black spot to a distance corresponding to 10% to 100% of the size of the black spot in an outward direction from the black spot.

[0010] The black dot peripheral region may have a shape surrounding the black dot.

[0011] The black spot surrounding region may contain Si elements, Ba elements, and Ti elements.

[0012] The dielectric layer may contain a barium titanate-based main component containing Ba and Ti, and a subcomponent containing Si.

[0013] The Si element contained in the black dots and the Si element contained in the regions surrounding the black dots may have a molar ratio of 1:8 to 8:1 based on 100 parts by mole of the barium titanate-based main component.

[0014] The auxiliary components may further include one or more selected from Dy, Tb, Mn, V, Ba, Al, Ca, and Sn.

[0015] Another embodiment provides a method for manufacturing a multilayer ceramic capacitor, the method comprising the steps of: mixing a barium titanate-based main component powder and a sub-component powder to prepare a dielectric slurry; preparing a dielectric green sheet using the dielectric slurry and 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; firing the dielectric green sheet laminate to prepare a capacitor body including a dielectric layer and an internal electrode layer; and forming an external electrode on one surface of the capacitor body, wherein the dielectric layer includes a plurality of dielectric crystal grains, at least one of the plurality of dielectric crystal grains includes a black dot, the number of the black dots being 4 to 16 per cross-sectional area of ​​1 μm × 1 μm in the dielectric layer, and the black dots include Si element and do not include at least two elements selected from Ba, Ti, and O.

[0016] The barium titanate-based main component powder can be prepared by a hydrothermal synthesis method including the steps of: mixing a barium raw material and a titanium raw material to prepare barium titanate seeds; and growing the barium titanate seeds.

[0017] The barium raw material and the titanium raw material may be mixed so that the molar ratio of Ba / Ti is 1.020 or more and 1.050 or less.

[0018] The grain growing step may be carried out at a temperature of 208°C or more and 242°C or less.

[0019] The sub-component powder may include a Si-containing compound.

[0020] The Si-containing compound may be contained in an amount of 0.5 to 4 parts by mole relative to 100 parts by mole of the barium titanate-based main component powder.

[0021] The auxiliary component powder may further include one or more selected from a Dy-containing compound, a Tb-containing compound, a Mn-containing compound, a V-containing compound, a Ba-containing compound, an Al-containing compound, a Ca-containing compound, and a Sn-containing compound. [Effects of the Invention]

[0022] The multilayer ceramic capacitor according to an embodiment may include a dielectric layer with a controlled material defect level, thereby improving not only voltage resistance characteristics but also high-temperature harsh reliability and humidity resistance reliability. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a perspective view illustrating a multilayer ceramic capacitor according to an embodiment; [Figure 2] FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line II' in FIG. [Figure 3] FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line II-II′ in FIG. [Figure 4] 2 is an exploded perspective view showing the laminated structure of internal electrode layers in the capacitor body of FIG. 1. FIG. [Figure 5] FIG. 2 is a schematic diagram illustrating a cross section of a dielectric layer according to one embodiment. [Figure 6] 1 is a TEM (transmission electron microscope) image of a dielectric layer according to Example 1. [Figure 7] 1 is a TEM (transmission electron microscope) image of a dielectric layer according to Comparative Example 1. [Figure 8a] 1 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 1. [Figure 8b] 1 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 1. [Figure 8c] 1 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 1. [Figure 8d]1 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 1. [Figure 8e] 1 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 1. [Figure 9a] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 2. [Figure 9b] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 2. [Figure 9c] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 2. [Figure 9d] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 2. [Figure 9e] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 2. [Figure 10a] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 3. [Figure 10b] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 3. [Figure 10c] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 3. [Figure 10d] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 3. [Figure 10e] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 3. [Figure 11a] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 4. [Figure 11b] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 4. [Figure 11c] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 4. [Figure 11d] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 4. [Figure 11e] 10 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Example 4. [Figure 12a] 1 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Comparative Example 1. [Figure 12b] 1 is a TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis image of a dielectric layer according to Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. In the drawings, parts unnecessary for the explanation are omitted in order to clearly explain the present invention, and the same reference numerals are used throughout the specification to refer to the same or similar components. In addition, in the accompanying drawings, some components are exaggerated, omitted, or shown schematically, and the size of each component does not completely reflect the actual size.

[0025] It should be understood that the attached drawings are merely for the purpose of facilitating understanding of the embodiments disclosed in this specification, and that the technical ideas disclosed in this specification are not limited by the attached drawings, and that all modifications, equivalents, or alternatives included within the idea and technical scope of the present invention are included.

[0026] Terms including ordinal numbers such as first, second, etc. may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

[0027] Furthermore, when a layer, film, region, plate, or other part is said to be "above" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part between them. Conversely, when a part is said to be "directly above" another part, it means that there is no other part between them. Furthermore, being "above" a reference part means being located above or below the reference part, and does not necessarily mean being located "above" in the opposite direction of gravity.

[0028] Throughout the specification, the use of terms such as "comprises" or "having" is intended to specify the presence of a stated feature, number, step, operation, component, part, or combination thereof, but should be understood to not preclude the possible presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Thus, when a part "comprises" a certain component, this means that it can further include other components, rather than excluding other components, unless specifically stated to the contrary.

[0029] Also, throughout the specification, "on a plane" means when the subject part is viewed from above, and "on a cross section" means when the subject part is cut vertically and viewed from the side.

[0030] Furthermore, throughout the specification, when the term "connected" is used, it does not only mean that two or more components are directly connected, but also that two or more components are indirectly connected via other components, that they are not only physically connected but also electrically connected, or that they are all referred to by different names depending on their position or function.

[0031] Hereinafter, a multilayer ceramic capacitor according to an embodiment will be described with reference to FIGS.

[0032] FIG. 1 is a perspective view showing a multilayer ceramic capacitor according to one 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 an exploded perspective view showing the stacking structure of internal electrode layers in the capacitor body of FIG. 1.

[0033] The L axis, W axis, and T axis shown in FIGS. 1 to 4 respectively indicate the longitudinal direction, width direction, and thickness direction of the capacitor body 110. 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 in the same concept as the stacking direction of the dielectric layers 111. The longitudinal direction (L axis direction) is a direction extending parallel to the wide surface (main surface) of the sheet-shaped component and substantially perpendicular to the thickness direction (T axis direction). For example, it may be a direction in which the first external electrode 131 and the second external electrode 132 are located on both sides. The width direction (W axis direction) may be a direction extending parallel to the wide surface (main surface) of the sheet-shaped component and substantially perpendicular to the thickness direction (T axis direction) and the longitudinal direction (L axis direction). The length of the sheet-shaped component in the longitudinal direction (L axis direction) may be longer than the length in the width direction (W axis direction).

[0034] 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 outside 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).

[0035] For example, the capacitor body 110 may have a substantially hexahedral shape.

[0036] For the convenience of describing one embodiment, in the capacitor body 110, the opposite surfaces facing each other in the thickness direction (T-axis direction) are defined as the first and second surfaces, and are connected to the first and second surfaces; the opposite surfaces facing each other in the longitudinal direction (L-axis direction) are defined as the third and fourth surfaces, and are connected to the first and second surfaces and are connected to the third and fourth surfaces; and the opposite surfaces facing each other in the width direction (W-axis direction) are defined as the fifth and sixth surfaces.

[0037] As an example, the first surface of the lower surface may be the surface facing the mounting direction. Furthermore, 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 convex central portions, and the corners that are the boundaries between the surfaces may be rounded.

[0038] 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.

[0039] 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 electrode layers 121 and second internal electrode layers 122 that are alternately arranged in the thickness direction (T-axis direction) with the dielectric layers 111 sandwiched between them.

[0040] At this time, the boundaries between the adjacent dielectric layers 111 of the capacitor body 110 may be so integrated that they are difficult to identify without using a scanning electron microscope (SEM).

[0041] The capacitor body 110 can include an active area and cover areas 112, 113.

[0042] The active region is a region where the dielectric layers 111 and the internal electrode layers 121, 122 are alternately arranged, and is a portion that contributes to forming the capacitance of the multilayer ceramic capacitor 100. Specifically, the active region may be a region where the first internal electrode layers 121 or the second internal electrode layers 122 stacked along the thickness direction (T-axis direction) overlap.

[0043] The cover regions 112 and 113 are margins in the thickness direction and may be located on the first and second surfaces of the active region in the thickness direction (T-axis direction), respectively. The cover regions 112 and 113 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.

[0044] Additionally, the capacitor body 110 may further include a side margin region.

[0045] The side margin regions are widthwise margins and may be located on both opposing ends of the active region in the widthwise direction (W-axis direction), i.e., on the fifth and sixth surfaces, respectively. The side margin regions may be formed by, when applying a conductive paste layer for an internal electrode layer to the surface of a dielectric green sheet, applying the conductive paste layer only to a portion of the surface of the dielectric green sheet, laminating dielectric green sheets on both side surfaces of the surface of the dielectric green sheet without applying the conductive paste layer, and then firing the laminate; however, the method of formation is not limited to this.

[0046] The cover regions 112, 113 and the side margin regions serve to prevent damage to the first internal electrode layer 121 and the second internal electrode layer 122 due to physical or chemical stress.

[0047] The dielectric layers, internal electrode layers, and external electrodes will be described in detail below.

[0048] [Dielectric layer] The dielectric layer will be described with reference to FIG.

[0049] FIG. 5 is a schematic diagram illustrating a cross section of a dielectric layer according to one embodiment.

[0050] Referring to FIG. 5, the dielectric layer 111 includes a plurality of dielectric grains 10, and at least one of the plurality of dielectric grains 10 includes a black dot 20.

[0051] The black dots 20 according to one embodiment contain silicon (Si) and may not contain at least two elements selected from barium (Ba), titanium (Ti), and oxygen (O). When the dielectric crystal grains 10 in the dielectric layer 111 have the black dots 20 of the above composition, the reliability and withstand voltage characteristics of the multilayer ceramic capacitor can be improved.

[0052] The black dots 20 may appear as defects in the dielectric crystal grains 10. However, the black dots 20 are distinguished from defects, pores, or voids that generally appear in dielectric materials by containing Si elements. That is, the defects, pores, and holes are empty and do not contain any components, and are therefore distinguished from the black dots 20 according to one embodiment.

[0053] The components constituting the black spots 20 may be derived from the barium titanate-based main and sub-components constituting the dielectric layer 111. For example, the Si element contained in the black spots 20 may be derived from a sub-component containing Si. The black spots 20 do not contain both elements, barium (Ba) and titanium (Ti), contained in the surrounding dielectric layer 111, but rather contain one of the two elements or none of the two elements, and are therefore distinguishable from the surrounding area within the dielectric layer 111.

[0054] The number of black dots 20 per 1 μm×1 μm cross-sectional area in the dielectric layer 111 may be 4 to 16, for example, 5 to 15, 6 to 14, or 7 to 13. When the dielectric layer 111 contains the black dots 20 in this number range, the reliability and withstand voltage characteristics of the multilayer ceramic capacitor can be improved. Specifically, if there are no black dots 20 within the dielectric crystal grains 10, a uniform reaction does not occur with respect to the diffusion of the material, making it difficult to obtain dielectric crystal grains 10 of uniform size within the dielectric layer 111. If there are too many black dots 20, a partial discharge breakdown mode may occur due to the concentration of an electric field at the black dots at high temperatures.

[0055] The number of black dots 20 having the above-mentioned composition in the dielectric layer 111 can be confirmed by TEM-EDS (Transmission Electron Microscopy-Energy Dispersive Spectroscopy) analysis of the dielectric layer.

[0056] Specifically, the multilayer ceramic capacitor 100 is immersed in an epoxy mixture and cured. The W-axis and T-axis surfaces (WT surfaces) of the capacitor body 110 are then polished to a depth of 1 / 2 in the L-axis direction, fixed, and maintained in a vacuum atmosphere chamber to obtain a cross-sectional sample for observing the active region where the dielectric layer 111 intersects with the internal electrode layers 121 and 122. The active region of the cross-sectional sample can then be measured using a transmission electron microscope (TEM) to reveal at least one layer, e.g., one to five layers, of the dielectric layer 111. For example, the TEM can be performed using a focused ion beam (Xe-FIB) at an acceleration voltage of 200 kV in an area of ​​approximately 2.5 μm × 2.5 μm where at least one layer of the dielectric layer 111 is visible in the active region. The number of black spots 20 in the dielectric layer 111 can be determined from the TEM image of the measured cross-sectional sample. Next, EDS (Energy Dispersive Spectroscopy) analysis can be performed on the TEM image of the measured cross-sectional sample to identify the components contained in the black spots 20 in the dielectric layer 111.

[0057] The size of the black dots 20 may be 5 nm to 40 nm, for example, 7 nm to 38 nm, 10 nm to 35 nm, 12 nm to 33 nm, or 15 nm to 30 nm. The size of the black dots 20 indicates the diameter measured on a line drawn with respect to the major axis of the dielectric crystal grain 10. When the size of the black dots is within this range, a multilayer ceramic capacitor with excellent reliability and withstand voltage characteristics can be ensured.

[0058] The size of the black spots 20 can be confirmed from a TEM image of the cross-sectional sample measured by the above-mentioned method.

[0059] The dielectric layer 111 may further include a black spot peripheral region 30. The black spot peripheral region 30 may be defined as a region extending from the black spot 20 to a distance corresponding to 10% to 100% of the size of the black spot 20 in an outward direction from the black spot 20. For example, the black spot peripheral region 30 may be in a form surrounding the black spot 20.

[0060] The black spot peripheral region 30 can contain Si, Ba, and Ti elements. Si, Ba, and Ti can all be derived from the main and subcomponents of the barium titanate-based material that forms the dielectric layer 111. The black spot peripheral region 30 has a different composition from the black spots 20, thereby separating the black spots 20 from the surrounding area within the dielectric layer 111.

[0061] The composition of the black spot peripheral region 30 can be confirmed by TEM-EDS (Transmission Electron Microscopy-Energy Dispersive Spectroscopy) analysis of the dielectric layer measured by the method described above.

[0062] The dielectric layer 111 may contain a barium titanate-based main component and a subcomponent.

[0063] The main component of the barium titanate-based dielectric base material has a high dielectric constant and contributes to the formation of the dielectric constant of the multilayer ceramic capacitor 100 .

[0064] The main component of the barium titanate system is a compound containing barium (Ba) and titanium (Ti), and may include, for example, BaTiO3, Ba(Ti,Zr)O3, Ba(Ti,Sn)O3, (Ba,Ca)TiO3, (Ba,Ca)(Ti,Ca)O3, (Ba,Ca)(Ti,Zr)O3, (Ba,Ca)(Ti,Sn)O3, (Ba,Sr)TiO3, (Ba,Sr)(Ti,Zr)O3, (Ba,Sr)(Ti,Sn)O3, or combinations thereof.

[0065] The secondary component may include silicon (Si). In addition, the secondary component may further include one or more selected from dysprosium (Dy), terbium (Tb), manganese (Mn), vanadium (V), barium (Ba), aluminum (Al), calcium (Ca), and tin (Sn).

[0066] According to one embodiment, the molar ratio of the Si element contained in each black dot 20 to the Si element contained in the black dot peripheral region 30 may be 1:8 to 8:1 based on 100 molar parts of the barium titanate-based main component, for example, 1:7 to 7:1, 1:6 to 6:1, 1:5 to 5:1, or 1:4 to 4:1. When the molar ratio of the Si element contained in each black dot 20 to the black dot peripheral region 30 is within this range, the reliability and withstand voltage characteristics of the multilayer ceramic capacitor can be improved.

[0067] Such a molar ratio can be confirmed by TEM-EDS (Transmission Electron Microscopy-Energy Dispersive Spectroscopy) analysis of the dielectric layer measured by the above-mentioned method.

[0068] The average thickness (average length in the T-axis direction) of the dielectric layers 111 may be 0.1 μm or more and 8.0 μm or less, for example, 0.1 μm or more and 6.0 μm or less. When the average thickness of the dielectric layers 111 is within this range, the reliability of the multilayer ceramic capacitor is excellent.

[0069] The average thickness of the dielectric layer 111 can be measured by immersing the multilayer ceramic capacitor 100 in an epoxy mixture, curing it, polishing it, and then ion milling it, followed by scanning electron microscope (SEM) analysis. The scanning electron microscope may be, for example, a Verios G4 product from Thermofisher Scientific, with measurement conditions of 10 kV, 0.2 nA, and an analysis magnification of 100x. Measurements may be performed to reveal at least one, three, five, or ten dielectric layers 111. In the SEM image, the center of the dielectric layer 111 in the longitudinal direction (L-axis direction) or width direction (W-axis direction) is used as a reference point, and the average thickness may be the arithmetic average of the thicknesses of the dielectric layer 111 at 10 points spaced apart by a predetermined distance from the reference point. The intervals between the 10 points can be adjusted according to the scale of a scanning electron microscope (SEM) image, and may be, for example, 1 μm to 100 μm, 1 μm to 50 μm, or 1 μm to 10 μm. In this case, all 10 points must be located within the dielectric layer 111. If all 10 points are not located within the dielectric layer 111, the positions of the reference points can be changed or the intervals between the 10 points can be adjusted.

[0070] [Internal electrode layer] The internal electrode layers 121, 122, i.e., the first internal electrode layer 121 and the second internal electrode layer 122, are electrodes having different polarities and are alternately arranged facing each other along the T-axis direction with the dielectric layer 111 sandwiched therebetween, and one end can be exposed through the third and fourth surfaces of the capacitor body 110, respectively.

[0071] The first internal electrode layer 121 and the second internal electrode layer 122 can be electrically insulated from each other by the dielectric layer 111 disposed therebetween.

[0072] The ends of the first internal electrode layer 121 and the second internal electrode layer 122, which are alternately exposed through the third and fourth surfaces of the capacitor body 110, can be electrically connected to the first external electrode 131 and the second external electrode 132, respectively.

[0073] The first internal electrode layer 121 and the second internal electrode layer 122 include a conductive metal, such as Ni, Cu, Ag, Pd, Au, or an alloy thereof, such as an Ag—Pd alloy.

[0074] Furthermore, the first internal electrode layers 121 and the second internal electrode layers 122 may contain dielectric particles of the same composition as the ceramic material contained in the dielectric layers 111 .

[0075] The first internal electrode layer 121 and the second internal electrode layer 122 may be formed using a conductive paste containing a conductive metal. The conductive paste may be printed by screen printing or gravure printing.

[0076] The average thickness of the first internal electrode layer 121 and the second internal electrode layer 122 may be 0.1 μm or more and 2 μm or less. The average thickness of the first internal electrode layer 121 and the second internal electrode layer 122 can be measured by scanning electron microscope (SEM) analysis. Here, the scanning electron microscope (SEM) analysis is the same as the method used to measure the average thickness of the dielectric layer 111 described above, so a description thereof will be omitted.

[0077] 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 stacked.

[0078] [External electrode] The external electrodes 131, 132, i.e., the first external electrode 131 and the second external electrode 132, are supplied with voltages of different polarities and can be electrically connected to the exposed portions of the first internal electrode layer 121 and the second internal electrode layer 122, respectively.

[0079] With the above configuration, when a predetermined voltage is applied to the first external electrode 131 and the second external electrode 132, charges are accumulated between the opposing first internal electrode layer 121 and second internal electrode layer 122. At this time, the capacitance of the multilayer ceramic capacitor 100 is proportional to the overlapping area of ​​the first internal electrode layer 121 and the second internal electrode layer 122 that overlap each other along the T-axis direction in the active region.

[0080] The first external electrode 131 and the second external electrode 132 may each include first and second connection portions arranged on the third and fourth surfaces of the capacitor body 110 and connected to the first internal electrode layer 121 and the second internal electrode layer 122, respectively, and first and second band portions arranged at the corners where the third and fourth surfaces of the capacitor body 110 meet the first and second surfaces or the fifth and sixth surfaces.

[0081] The first and second band portions may extend from the first and second connection portions to parts of the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110. The first and second band portions may serve to improve the bonding strength between the first external electrode 131 and the second external electrode 132.

[0082] The first external electrode 131 and the second external electrode 132 may each include a sintered metal layer in contact with the capacitor body 110, a conductive resin layer arranged to cover the sintered metal layer, and a plating layer arranged to cover the conductive resin layer.

[0083] The sintered metal layer may include a conductive metal and glass.

[0084] The conductive metal may include copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), alloys thereof, or combinations thereof. For example, copper (Cu) may include a copper (Cu) alloy. When the conductive metal includes copper, metals other than copper may be included in an amount of 5 molar parts or less per 100 molar parts of copper.

[0085] The glass may include a mixed oxide composition, such as one or more oxides selected from the group consisting of silicon oxide, boron oxide, aluminum oxide, transition metal oxide, alkali metal oxide, and alkaline earth metal oxide. The transition metal may be selected from the group consisting of zinc (Zn), titanium (Ti), copper (Cu), vanadium (V), manganese (Mn), iron (Fe), and nickel (Ni), the alkali metal may be selected from the group consisting of lithium (Li), sodium (Na), and potassium (K), and the alkaline earth metal may be one or more oxides selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0086] Alternatively, the conductive resin layer may be formed on the sintered metal layer, for example, to completely cover the sintered metal layer. Alternatively, the first external electrode 131 and the second external electrode 132 may not include a sintered metal layer, in which case the conductive resin layer may be in direct contact with the capacitor body 110.

[0087] The conductive resin layer extends on the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110, and the length of the region (i.e., band portion) in which the conductive resin layer is arranged extending on the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110 may be longer than the length of the region (i.e., band portion) in which the sintered metal layer is arranged extending on the first and second surfaces or the fifth and sixth surfaces of the capacitor body 110. In other words, the conductive resin layer may be formed on the sintered metal layer so as to completely cover the sintered metal layer.

[0088] The conductive resin layer contains a resin and a conductive metal.

[0089] The resin contained in the conductive resin layer is not particularly limited as long as it has bonding and impact absorption properties and can be mixed with the conductive metal powder to form a paste, and may include, for example, phenolic resin, acrylic resin, silicone resin, epoxy resin, or polyimide resin.

[0090] The conductive metal contained in the conductive resin layer serves to electrically connect the first internal electrode layer 121 and the second internal electrode layer 122 or the sintered metal layer.

[0091] 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 composed of only flake shapes, only spherical shapes, or a mixture of flake shapes and spherical shapes.

[0092] Here, spherical may include shapes that are not perfectly spherical, for example, shapes in which the ratio of the major axis to the minor axis (major axis / minor axis) is 1.45 or less. Flake-like powder means powder having a flat and elongated shape, and is not particularly limited, but may, for example, have a ratio of the major axis to the minor axis (major axis / minor axis) of 1.95 or more.

[0093] The first external electrode 131 and the second external electrode 132 may further include a plating layer disposed on the outer side of the conductive resin layer.

[0094] 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 in alloys thereof. For example, the plating layer may be a nickel (Ni) plating layer or a tin (Sn) plating layer, or may be a nickel (Ni) plating layer and a tin (Sn) plating layer stacked in sequence, or a tin (Sn) plating layer, a nickel (Ni) plating layer, and a tin (Sn) plating layer stacked in sequence. The plating layer may also include multiple nickel (Ni) plating layers and / or multiple tin (Sn) plating layers.

[0095] The plating layer can improve the mountability of the multilayer capacitor 100 to a substrate, structural reliability, durability against external forces, heat resistance, and equivalent series resistance (ESR).

[0096] [Manufacturing method of multilayer ceramic capacitor] A method for manufacturing the multilayer ceramic capacitor 100 according to an embodiment will now be described.

[0097] The multilayer ceramic capacitor 100 according to one embodiment can be manufactured through the steps of: preparing a dielectric slurry by mixing a barium titanate-based main component powder and a sub-component powder; preparing a dielectric green sheet using the dielectric slurry and 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; firing the dielectric green sheet laminate to prepare a capacitor body including a dielectric layer and an internal electrode layer; and forming an external electrode on one surface of the capacitor body.

[0098] The barium titanate-based main component powder is a compound containing barium (Ba) and titanium (Ti), and may include, for example, BaTiO3, Ba(Ti,Zr)O3, Ba(Ti,Sn)O3, (Ba,Ca)TiO3, (Ba,Ca)(Ti,Ca)O3, (Ba,Ca)(Ti,Zr)O3, (Ba,Ca)(Ti,Sn)O3, (Ba,Sr)TiO3, (Ba,Sr)(Ti,Zr)O3, (Ba,Sr)(Ti,Sn)O3, or combinations thereof.

[0099] The barium titanate-based main component powder can be produced by hydrothermal synthesis, specifically by mixing a barium raw material and a titanium raw material to produce barium titanate seeds, and then growing the barium titanate seeds.

[0100] The barium source can contain barium hydroxide, for example, barium hydroxide octahydrate (Ba(OH)2·8H2O). The barium source can be ionized by heating it to 60°C or higher.

[0101] The titanium raw material is hydrous titanium (TiO x / 2 (OH) 4-x The titanium raw material can be a sol dispersed in an acid or base.

[0102] The barium raw material and the titanium raw material may be mixed so that the molar ratio of Ba / Ti is 1.020 to 1.050, for example, 1.022 to 1.048, or 1.024 to 1.046. When the barium raw material and the titanium raw material are mixed in this ratio, the number of black dots 20 in the dielectric layer 111 can be within an appropriate range, thereby ensuring a multilayer ceramic capacitor with excellent reliability and withstand voltage characteristics.

[0103] Rapid stirring, microwave or ultrasound can be used to speed up the formation of barium titanate seeds.

[0104] Next, prior to the step of grain growing the barium titanate seeds, the prepared barium titanate seeds may be mixed with pure water and a grain growth inhibitor.

[0105] Grain growth inhibitors can be used to retard grain growth, and examples of such inhibitors include substances that can reduce the polarity of the solvent, such as alcohols such as butylene glycol, dimethoxyethane, hexanediol, hexylene glycol, and methoxyethanol; substances that reduce the pH, such as acids such as acetic acid and nitric acid; and substances that inhibit reprecipitation, such as surfactants such as sodium alkylsulfate, alkylbenzene sulfonate, N-acrylic amino acid salts, acrlyamide, diethanolamine, and amine oxide.

[0106] Next, the grain growth step may be performed at a high temperature, specifically, at a temperature of 208° C. to 242° C., for example, 209° C. to 241° C., or 210° C. to 240° C. When the grain growth is performed within this temperature range, an appropriate number of black dots 20 can be obtained in the dielectric layer 111, thereby ensuring a multilayer ceramic capacitor with excellent reliability and withstand voltage characteristics.

[0107] The grain growth stage may be carried out for 1 hour or more and 72 hours or less, for example, 3 hours or more and 70 hours or less.

[0108] The grain-grown material can then be dried to produce a barium titanate-based powder.

[0109] The sub-component powder may include a Si-containing compound.

[0110] The Si-containing compound may be included in an amount of 0.5 to 4 molar parts, for example, 0.7 to 3.8 molar parts, 0.9 to 3.6 molar parts, 1.1 to 3.4 molar parts, 1.3 to 3.2 molar parts, or 1.5 to 3.0 molar parts, relative to 100 molar parts of the barium titanate-based main component powder. When the Si-containing compound is included in this amount, an appropriate number of black dots 20 can be obtained in the dielectric layer 111, thereby ensuring a multilayer ceramic capacitor with excellent reliability and withstand voltage characteristics.

[0111] The secondary component powder may further include one or more additional components selected from a Dy-containing compound, a Tb-containing compound, a Mn-containing compound, a V-containing compound, a Ba-containing compound, an Al-containing compound, a Ca-containing compound, and an Sn-containing compound.

[0112] The Dy-containing compound may be contained in an amount of 0.1 to 1 molar part, for example, 0.2 to 0.9 molar parts, or 0.3 to 0.8 molar parts, per 100 molar parts of the barium titanate-based main component powder. The Tb-containing compound may be contained in an amount of 0.1 to 1 molar part, for example, 0.2 to 0.9 molar parts, or 0.3 to 0.8 molar parts, per 100 molar parts of the barium titanate-based main component powder. The Mn-containing compound may be contained in an amount of 0.2 molar parts or less, for example, 0.01 to 0.2 molar parts, or 0.05 to 0.15 molar parts, per 100 molar parts of the barium titanate-based main component powder. The V-containing compound may be contained in an amount of 0.15 molar parts or less per 100 molar parts of the barium titanate-based main component powder, for example, 0.01 to 0.15 molar parts, or 0.05 to 0.1 molar parts. The Ba-containing compound may be contained in an amount of 2 molar parts or less per 100 molar parts of the barium titanate-based main component powder, for example, 0.1 to 2 molar parts, or 0.5 to 1.5 molar parts. The Al-containing compound may be contained in an amount of 0.4 to 0.6 molar parts per 100 molar parts of the barium titanate-based main component powder, for example, 0.45 to 0.55 molar parts. The Ca-containing compound may be contained in an amount of 0.8 molar parts or less per 100 molar parts of the barium titanate-based main component powder, for example, 0.1 to 0.8 molar parts, or 0.3 to 0.6 molar parts. The Sn-containing compound may be included in an amount of 0.1 to 5 molar parts, for example, 0.5 to 4.5 molar parts, or 1 to 4 molar parts, relative to 100 molar parts of the barium titanate-based main component powder. When the additional component is included in the above content range, the multilayer ceramic capacitor has excellent reliability and withstand voltage characteristics.

[0113] The powders of the minor components, i.e., the Si-containing compound, the Dy-containing compound, the Tb-containing compound, the Mn-containing compound, the V-containing compound, the Ba-containing compound, the Al-containing compound, the Ca-containing compound, and the Sn-containing compound, may be oxides, nitrides, or salt compounds, or may be used in the form of a sol dispersed in an organic solvent.

[0114] The dielectric slurry can be produced by additionally mixing additives such as dispersants, binders, plasticizers, lubricants, antistatic agents, and solvents.

[0115] The dispersant may include, for example, a phosphate ester-based dispersant, a polycarboxylic acid-based dispersant, or a combination thereof. The dispersant may be mixed in an amount of 0.1 to 5 parts by weight, for example, 0.3 to 3 parts by weight, per 100 parts by weight of the barium titanate-based main component powder. When the dispersant is mixed within the above content range, the dispersibility of the dielectric slurry is excellent, and the amount of impurities contained in the manufactured dielectric layer can be reduced.

[0116] The binder may be, for example, an acrylic resin, a polyvinyl butyl resin, a polyvinyl acetal resin, an ethyl cellulose resin, etc. The binder may be added in an amount of 0.1 to 50 parts by weight, for example, 3 to 30 parts by weight, per 100 parts by weight of the barium titanate-based main component powder. When the binder is mixed within the above content range, the dispersibility of the dielectric slurry is excellent, and the amount of impurities contained in the manufactured dielectric layer can be reduced.

[0117] Examples of the plasticizer include phthalic acid compounds such as dioctyl phthalate, benzyl butyl phthalate, dibutyl phthalate, dihexyl phthalate, di(2-ethylhexyl) phthalate, and di(2-ethylbutyl) phthalate; adipic acid compounds such as dihexyl adipate and di(2-ethylhexyl) adipate; glycol compounds such as ethylene glycol, diethylene glycol, and triethylene glycol; and glycol ester compounds such as triethylene glycol dibutyrate, triethylene glycol di(2-ethylbutyrate), and triethylene glycol di(2-ethylhexanoate). The plasticizer can be added in an amount of 0.1 to 20 parts by weight, for example, 1 to 10 parts by weight, per 100 parts by weight of the barium titanate-based main component powder. When the plasticizer is mixed within the above content range, the dielectric slurry has excellent dispersibility and the amount of impurities contained in the manufactured dielectric layer can be reduced.

[0118] The solvent may be an aqueous solvent such as water; an alcoholic solvent such as ethanol, methanol, benzyl alcohol, or methoxyethanol; a glycol solvent such as ethylene glycol or diethylene glycol; a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone; an ester solvent such as butyl acetate, ethyl acetate, carbitol acetate, or butyl carbitol acetate; an ether solvent such as methyl cellosolve, ethyl cellosolve, butyl ether, or tetrahydrofuran; or an aromatic solvent such as benzene, toluene, or xylene. The solvent may be an alcoholic solvent or an aromatic solvent, taking into consideration the solubility and dispersibility of the various additives contained in the dielectric slurry. The solvent may be mixed in an amount of 50 to 1,000 parts by weight per 100 parts by weight of the barium titanate-based main component powder, for example, 100 to 500 parts by weight. When the solvent is mixed within the above content range, the dielectric slurry components can be sufficiently mixed, and subsequent solvent removal is easy.

[0119] The dielectric slurry can be mixed using a wet ball mill or an agitator mill. When using zirconia balls in a wet ball mill, wet mixing can be carried out using a plurality of zirconia balls having a diameter of 0.1 mm to 10 mm for 8 hours to 48 hours, or 10 hours to 24 hours.

[0120] The produced dielectric slurry is formed into a dielectric layer after firing.

[0121] The produced dielectric slurry can be formed into a sheet shape by a tape forming method such as a doctor blade method or a calendar roll method, for example, using an on-roll forming coater of a head discharge type, and then drying the formed body to obtain a dielectric green sheet.

[0122] To form a conductive paste layer that will become an internal electrode layer after firing, a conductive paste can be produced by mixing a conductive powder made of a conductive metal or its alloy, a binder, and a solvent. If necessary, barium titanate powder may also be mixed in as a co-material. The co-material can suppress sintering of the conductive powder during the firing process. The conductive paste is applied in a predetermined pattern to the surface of a dielectric green sheet by various printing methods such as screen printing or a transfer method to form a conductive paste layer.

[0123] The conductive powder may include nickel (Ni) or a nickel (Ni) alloy.

[0124] Next, a plurality of dielectric green sheets on which the internal electrode patterns are formed are laminated and then pressed in the lamination direction to manufacture a dielectric green sheet laminate. At this time, the dielectric green sheets and the internal electrode layer patterns can be laminated so that the dielectric green sheets are located on the upper and lower surfaces of the dielectric green sheet laminate in the lamination direction.

[0125] The manufactured dielectric green sheet laminate may optionally be cut into a predetermined size by dicing or the like.

[0126] Furthermore, the dielectric green sheet laminate can be solidified and dried as needed to remove plasticizers and the like, and after solidification and drying, can be barrel polished using a horizontal centrifugal barrel machine or the like. In barrel polishing, the dielectric green sheet laminate is placed in a barrel container together with media and a polishing solution, and the barrel container is subjected to rotational motion, vibration, or the like, to polish away unnecessary parts such as burrs generated during cutting. Furthermore, after barrel polishing, the dielectric green sheet laminate can be washed with a cleaning liquid such as water and dried.

[0127] The dielectric green sheet laminate can then be debindered (plasticized) and fired to produce a capacitor body.

[0128] The binder removal treatment conditions can be appropriately adjusted depending on the components of the dielectric layers and the internal electrode layers. For example, the temperature rise rate during 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 atmosphere during binder removal treatment may be air or a reducing atmosphere.

[0129] The firing conditions can be appropriately adjusted depending on the composition of the main component of the dielectric layer and the composition of the main component of the internal electrode layer. For example, firing may be performed at a temperature of 1100°C or higher and 1400°C or lower, for example, at a temperature of 1200°C or higher and 1350°C or lower. Furthermore, firing may be performed for 0.5 hours or higher and 8 hours or lower, for example, 1 hour or higher and 3 hours or lower. Furthermore, firing may be performed in a reducing atmosphere, for example, an atmosphere containing a humidified mixed gas of nitrogen and hydrogen, for example, under conditions of a hydrogen concentration of 1.0% or lower. When the internal electrode layer contains nickel (Ni) or a nickel (Ni) alloy, the oxygen partial pressure in the firing atmosphere is 1.0 x 10 -14 MPa or more 1.0 x 10 -10 MPa or less.

[0130] After the firing treatment, annealing can be carried out as necessary. Annealing is a treatment for reoxidizing the dielectric layer, and can be carried out when firing is carried out 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 annealing temperature may be 950°C or higher and 1150°C or lower, the annealing time may be 0 hours or higher and 20 hours or lower, and the temperature increase rate may be 50°C / hour or higher and 500°C / hour or lower. The annealing atmosphere may be a humidified nitrogen gas (N2) atmosphere, and the oxygen partial pressure may be 1.0 x 10 -9 MPa or more 1.0 x 10 -5 MPa or less.

[0131] In the binder removal treatment, firing treatment, or annealing treatment, a wetter or the like can be used to humidify the nitrogen gas or mixed gas, and in this case, the water temperature may be 5° C. or higher and 75° C. or lower. The binder removal treatment, firing treatment, and annealing treatment may be performed consecutively or independently.

[0132] Optionally, surface treatment such as sandblasting, laser irradiation, barrel polishing, etc. may be performed on the third and fourth surfaces of the manufactured capacitor body 110. By performing such surface treatment, the ends of the first and second internal electrode layers are exposed on the outermost surfaces of the third and fourth surfaces, which improves the electrical connection between the first and second external electrodes and the first and second internal electrode layers, and may facilitate the formation of alloy parts.

[0133] Next, an external electrode is formed on one surface of the manufactured capacitor body 110 .

[0134] For example, a paste for forming a sintered metal layer may be applied to the external electrodes and then sintered to form a sintered metal layer.

[0135] The paste for forming a sintered metal layer may contain a conductive metal and glass. The conductive metal and glass have been described above, so a repeated description will be omitted. The paste for forming a sintered metal layer may optionally contain a binder, a solvent, a dispersant, a plasticizer, an oxide powder, and the like. Examples of binders that can be used include ethyl cellulose, acrylic, butyral, and the like. Examples of solvents that can be used include organic solvents such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, and toluene, as well as aqueous solvents.

[0136] The paste for forming a sintered metal layer can be applied to the outer surface of the capacitor body 110 by various printing methods such as dipping, screen printing, etc., application using a dispenser, spraying using a spray, etc. The paste for forming a sintered metal layer is applied to at least the third and fourth surfaces of the capacitor body 110, and can also be selectively applied to parts of the first, second, fifth, or sixth surfaces on which the band portions of the first and second external electrodes are formed.

[0137] Thereafter, the capacitor body 110 coated with the paste for forming a sintered metal layer is dried and sintered at a temperature of 700° C. to 1000° C. for 0.1 to 3 hours to form a sintered metal layer.

[0138] Alternatively, a conductive resin layer forming paste may be applied to the outer surface of the obtained capacitor body 110 and then cured to form a conductive resin layer.

[0139] The paste for forming the conductive resin layer may contain a resin and, optionally, a conductive metal or a non-conductive filler. The conductive metal and resin have been described above, so a repeated description will be omitted. The paste for forming the conductive resin layer may also optionally contain a binder, a solvent, a dispersant, a plasticizer, an oxide powder, etc. Examples of binders that can be used include ethyl cellulose, acrylic, butyral, etc., and solvents that can be used include organic solvents or aqueous solvents such as terpineol, butyl carbitol, alcohol, methyl ethyl ketone, acetone, and toluene.

[0140] As an example, the conductive resin layer can be formed by dipping the capacitor body 110 in a paste for forming the conductive resin layer and then hardening it, 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 to the surface of the capacitor body 110 and then hardening it.

[0141] Next, a plating layer is formed on the outside of the conductive resin layer.

[0142] For example, the plating layer may be formed by a plating method, such as sputtering or electric deposition.

[0143] The above-described embodiments will be described in more detail with reference to the following examples, which are provided for illustrative purposes only and are not intended to limit the scope of the invention.

[0144] (Manufacturing of multilayer ceramic capacitors) [Examples 1 to 7 and Comparative Examples 1 to 6] Barium hydroxide octahydrate (Ba(OH)2·8H2O) was mixed with titanium oxide (TiO2) sol heated to over 60°C to produce barium titanate seeds. The Ba(OH)2·8H2O and TiO2 sol were mixed to achieve the Ba / Ti molar ratio shown in Table 1 below. The barium titanate seeds were then grown at the temperatures shown in Table 1 below and dried to produce barium titanate (BaTiO3) main component powder.

[0145] The produced BaTiO3 main component powder and the subcomponent powders, 2.5 molar parts of SiO2, 0.5 molar parts of Dy2O3, 0.5 molar parts of Tb2O3, 0.1 molar parts of MnO2, 0.08 molar parts of V2O5, 1 molar part of BaCO3, 0.5 molar parts of Al2O3, 0.4 molar parts of CaCO3, and 2.5 molar parts of SnO2, were mixed with 100 molar parts of the BaTiO3 main component powder to produce a dielectric slurry.

[0146] The dielectric slurry was prepared by mechanical milling after adding ethanol / toluene, a wetting dispersant, and polyvinyl butyral (PVB) resin as a binder using zirconia balls (ZrO2 balls) as a dispersion medium.

[0147] The prepared dielectric slurry was used in a head-discharging on-roll forming coater to prepare a dielectric green sheet.

[0148] A conductive paste layer containing nickel (Ni) was printed on the surface of the dielectric green sheet, and the dielectric green sheets on which the conductive paste layer was formed were stacked and pressed together to manufacture a dielectric green sheet laminate.

[0149] The dielectric green sheet laminate was subjected to a plasticization process at 400°C or less in a nitrogen atmosphere, and then fired at a firing temperature of 1300°C or less and with a hydrogen concentration of 1.0% H2 or less.

[0150] Next, a multilayer ceramic capacitor was manufactured through processes such as external electrodes and plating.

[0151] [Table 1]

[0152] [Evaluation 1: TEM analysis] The multilayer ceramic capacitors manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 were analyzed by TEM (Transmission Electron Microscope), and the results are shown in Table 2 below and FIGS.

[0153] Specifically, the multilayer ceramic capacitors manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 were placed in an epoxy mixture and cured. The W-axis and T-axis (WT) surfaces of the capacitor body were then polished to a depth of 1 / 2 in the L-axis direction. The capacitors were then fixed and placed in a vacuum chamber to obtain cross-sectional samples for observing the active region where the dielectric layers and internal electrode layers intersect. Next, the cross-sectional samples were measured using a transmission electron microscope (TEM) to ensure that at least one dielectric layer was visible in the active region. TEM measurements were performed using a Xe-FIB (focused ion beam) at an accelerating voltage of 200 kV in an area of ​​approximately 2.5 μm × 2.5 μm where at least one dielectric layer was visible in the active region. The number of black dots per 1 μm × 1 μm cross-sectional area in the dielectric layer was determined from the TEM images of the measured cross-sectional samples.

[0154] [Table 2]

[0155] FIG. 6 is a TEM (transmission electron microscope) image of the dielectric layer according to Example 1, and FIG. 7 is a TEM (transmission electron microscope) image of the dielectric layer according to Comparative Example 1.

[0156] 6 and 7, in Example 1, the number of black dots per cross-sectional area of ​​1 μm×1 μm in the dielectric layer was 4 as shown in Table 2, whereas in Comparative Example 1, there were no black dots.

[0157] [Evaluation 2: TEM-EDS analysis] The multilayer ceramic capacitors manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 were subjected to TEM-EDS (Transmission Electron Microscope-Energy Dispersive Spectroscopy) analysis, and the results are shown in FIGS. 8a to 12b.

[0158] Specifically, EDS (energy dispersive spectroscopy) analysis is performed on the TEM image of the cross-sectional sample obtained in Evaluation 1, and the components contained in the black spots 20 in the dielectric layer 111 can be confirmed.

[0159] 8a to 8e are TEM-EDS (transmission electron microscope-energy dispersive spectroscopy) analysis images of the dielectric layer according to Example 1, FIGS. 9a to 9e are TEM-EDS (transmission electron microscope-energy dispersive spectroscopy) analysis images of the dielectric layer according to Example 2, FIGS. 10a to 10e are TEM-EDS (transmission electron microscope-energy dispersive spectroscopy) analysis images of the dielectric layer according to Example 3, FIGS. 11a to 11e are TEM-EDS (transmission electron microscope-energy dispersive spectroscopy) analysis images of the dielectric layer according to Example 4, and FIGS. 12a to 12b are TEM-EDS (transmission electron microscope-energy dispersive spectroscopy) analysis images of the dielectric layer according to Comparative Example 1.

[0160] 8a to 12b, it can be seen that in Examples 1 to 4, the black dots contained in the dielectric crystal grains in the dielectric layer contain Si elements, but do not contain Ba, Ti, or O. In contrast, in Comparative Example 1, dots similar in shape to the black dots can be seen in Figures 12a to 12b, but since these do not contain Si elements, they are different from the black dots according to one embodiment and are presumed to be secondary phases.

[0161] [Evaluation 3: Withstand voltage characteristics] The breakdown voltage (BDV) of the multilayer ceramic capacitors manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 was measured, and the results are shown in Table 3 below.

[0162] The breakdown voltage (BDV) was measured by preparing 50 each of the multilayer ceramic capacitors manufactured in Examples 1 to 7 and Comparative Examples 1 to 6, applying a voltage in a sweep mode from 0 V to 1100 V in increments of 1.00000 V using a Keithely 2410 model meter, and measuring the voltage value at the moment when the current value reached 20 mA. The breakdown voltage was measured in a silicone oil bath.

[0163] The minimum and average values ​​of the measured BDV are shown in Table 3 below.

[0164] [Table 3]

[0165] From Table 3, it can be seen that in Examples 1 to 7, in which the number of black dots per cross-sectional area of ​​1 μm×1 μm in the dielectric layer is 4 to 16 according to one embodiment, the breakdown voltage is higher and the withstand voltage characteristics are superior compared to Comparative Examples 1 and 2. On the other hand, in Comparative Examples 3 to 6, although the withstand voltage characteristics are superior, the high-temperature severe reliability and moisture resistance reliability are reduced as shown in Evaluation 4 described below.

[0166] [Rating 4: Reliability] The multilayer ceramic capacitors manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 were measured for high temperature severe reliability (HALT) and humidity resistance reliability, and the results are shown in Table 4 below.

[0167] Specifically, 40 multilayer ceramic capacitors each manufactured in Examples 1 to 7 and Comparative Examples 1 to 6 were prepared and mounted on a measurement board. The high temperature severe reliability (HALT) was measured using an ESPEC (PV-222, HALT) device under conditions of 150°C, 100 hours, and 100V, and the humidity resistance reliability was measured using an ESPEC (PR-3J, 8585) device under conditions of 85°C, relative humidity (RH) 85%, 32V, and 24 hours.

[0168] [Table 4]

[0169] From Table 4, it can be seen that in the case of Examples 1 to 7, in which the number of black dots per cross-sectional area of ​​1 μm×1 μm in the dielectric layer is 4 to 16 according to one embodiment, the high-temperature severe reliability and moisture resistance reliability are superior to those of Comparative Examples 1 to 6.

[0170] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made within the scope of the claims, the description of the invention, and the accompanying drawings, and it goes without saying that these also fall within the scope of the present invention. [Explanation of symbols]

[0171] 10: Dielectric grain 20: Sunspot 30: Area around sunspots 100: Multilayer ceramic capacitor 110: Capacitor body 111: Dielectric layer 121: First internal electrode layer 122: Second internal electrode layer 131: 1st external electrode 132:Second external electrode

Claims

1. a capacitor body including a dielectric layer and an internal electrode layer; an external electrode disposed outside the capacitor body; the dielectric layer includes a plurality of dielectric grains, at least one of the plurality of dielectric grains includes a black dot; the black dots are contained in the dielectric layer in a number of 4 to 16 per cross-sectional area of ​​1 μm×1 μm, The black dots contain Si elements and do not contain at least two elements selected from Ba, Ti, and O.

2. 2. The multilayer ceramic capacitor according to claim 1, wherein the size of the black dot measured on a line drawn with the major axis of the dielectric crystal grain as a reference is 5 nm to 40 nm.

3. 2. The multilayer ceramic capacitor of claim 1, wherein the dielectric layer further comprises a black dot peripheral region defined by a region extending from the black dot to a distance corresponding to 10% to 100% of the size of the black dot in an outward direction from the black dot.

4. The multilayer ceramic capacitor according to claim 3 , wherein the black dot peripheral region has a shape surrounding the black dot.

5. The multilayer ceramic capacitor according to claim 3 , wherein the black dot surrounding region contains Si elements, Ba elements, and Ti elements.

6. 2. The multilayer ceramic capacitor according to claim 1, wherein the dielectric layers contain a barium titanate-based main component containing Ba and Ti, and a subcomponent containing Si.

7. 7. The multilayer ceramic capacitor according to claim 6, wherein the Si element contained in the black dots and the Si element contained in the black dot peripheral regions have a molar ratio of 1:8 to 8:1 based on 100 molar parts of the barium titanate-based main component.

8. The multilayer ceramic capacitor according to claim 6 , wherein the minor components further include one or more selected from the group consisting of Dy, Tb, Mn, V, Ba, Al, Ca, and Sn.

9. mixing a barium titanate-based main component powder and a subcomponent powder to prepare a dielectric slurry; preparing a dielectric green sheet using the dielectric slurry and forming a conductive paste layer on a surface of the dielectric green sheet; laminating the dielectric green sheets on which the conductive paste layers are formed to manufacture a dielectric green sheet laminate; sintering the dielectric green sheet laminate to manufacture a capacitor body including dielectric layers and internal electrode layers; forming an external electrode on one surface of the capacitor body; The dielectric layer includes a plurality of dielectric crystal grains, at least one of the plurality of dielectric crystal grains includes a black dot, the number of the black dots is 4 to 16 per cross-sectional area of ​​1 μm×1 μm in the dielectric layer, and the black dots include Si element but do not include at least two elements selected from Ba, Ti, and O.

10. The barium titanate-based main component powder is Mixing a barium raw material and a titanium raw material to prepare barium titanate seeds; The method for manufacturing a multilayer ceramic capacitor according to claim 9 , wherein the multilayer ceramic capacitor is manufactured by a hydrothermal synthesis method, including a step of growing grains of the barium titanate seeds.

11. The method for manufacturing a multilayer ceramic capacitor according to claim 10 , wherein the barium raw material and the titanium raw material are mixed so that a molar ratio of Ba / Ti is 1.020 or more and 1.050 or less.

12. The method of claim 10, wherein the grain growth is performed at a temperature of 208°C to 242°C.

13. The method for producing a multilayer ceramic capacitor according to claim 9 , wherein the auxiliary component powder contains a Si-containing compound.

14. The method for producing a multilayer ceramic capacitor according to claim 13, wherein the Si-containing compound is contained in an amount of 0.5 to 4 parts by mole relative to 100 parts by mole of the barium titanate-based main component powder.

15. 14. The method for manufacturing a multilayer ceramic capacitor according to claim 13, wherein the auxiliary component powder further comprises one or more selected from the group consisting of a Dy-containing compound, a Tb-containing compound, a Mn-containing compound, a V-containing compound, a Ba-containing compound, an Al-containing compound, a Ca-containing compound, and a Sn-containing compound.

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