Multilayer capacitor

Abstract

The present disclosure provides a multilayer capacitor including: a capacitor body including a dielectric layer and an inner electrode; and an external electrode disposed outside the capacitor body, in which the dielectric layer includes a plurality of dielectric grains including barium titanate as a main component, at least one of the plurality of dielectric grains having a core-shell structure including a core and a shell, the average molar ratio of barium to titanium (Ba / Ti molar ratio) in the cores of the dielectric crystal grains is 0.9975 to 1.0055, and the average number of cores per unit area (1 [mu] m * 1 [mu] m) in the dielectric layer is 25 to 35.

Description

Technical Field

[0001] The present disclosure relates to a multilayer capacitor. Background Art

[0002] Recently, as electronic devices have rapidly become multifunctional and miniaturized, the miniaturization and performance improvement of electronic components have also developed rapidly. In addition, the demand for high reliability of electrical devices for automobiles or network equipment and electronic components for industrial use has also increased significantly.

[0003] To meet these market demands, the competition in the technology development of passive components such as inductors, capacitors, or resistors is accelerating. In particular, a great deal of effort is required to capture the market by developing various products of multilayer ceramic capacitors (MLCCs), whose use and applications as passive components are increasing continuously.

[0004] In addition, a multilayer capacitor is a capacitor manufactured by stacking dielectric layers and internal electrodes, and is used in various electronic devices such as mobile phones, laptop computers, and liquid crystal display televisions (LCD TVs). In particular, with the development of automotive electronic control technology, the demand for automobiles has increased, and with the development of miniaturization and high functionality of electronic devices for vehicles, high-temperature resistance and moisture resistance characteristics of multilayer capacitors are required.

[0005] BaTiO 3 (barium titanate), which is a piezoelectric and optoelectronic material, has recently been mainly used in multilayer capacitors. However, the number of companies supplying barium titanate powder worldwide is limited, and their manufacturing technologies are also limited. Summary of the Invention

[0006] The present disclosure provides a multilayer capacitor having an improved dielectric constant by controlling the average Ba / Ti molar ratio of the main component in the core of dielectric grains and / or the average area ratio of the shell of dielectric grains.

[0007] A multilayer capacitor according to some embodiments may include: a capacitor body including dielectric layers and internal electrodes; and external electrodes provided outside the capacitor body.

[0008] Wherein, the dielectric layer may include a plurality of dielectric grains including barium titanate as a main component.

[0009] At least one of the plurality of dielectric grains may have a core-shell structure including a core and a shell.

[0010] The average molar ratio of barium to titanium (Ba / Ti molar ratio) in the core of the at least one dielectric grain may be from 0.9975 to 1.0055.

[0011] An average number of cores per unit area (1 μm×1 μm) in the dielectric layer may be 25 to 35.

[0012] An average molar ratio of barium to titanium (Ba / Ti molar ratio) in the core of the at least one dielectric grain may be 0.9980 to 1.0050.

[0013] A ratio of an average area of ​​the shell included in the at least one dielectric grain having the core-shell structure to an average area of ​​the at least one dielectric grain having the core-shell structure may be 30% to 50%.

[0014] A ratio of an average area of ​​the shell included in the at least one dielectric grain having the core-shell structure to an average area of ​​the at least one dielectric grain having the core-shell structure may be 38% to 46%.

[0015] The main component may include BaTiO 3 、Ba(Ti,Zr)O 3 、Ba(Ti,Sn)O 3 、(Ba,Ca)TiO 3 、(Ba,Ca)(Ti,Zr)O 3 、(Ba,Ca)(Ti,Sn)O 3 、(Ba,Sr)TiO 3 、(Ba,Sr)(Ti,Zr)O 3 and (Ba,Sr)(Ti,Sn)O 3 At least one of the group consisting of.

[0016] The dielectric grains may further include secondary components.

[0017] The subcomponent may include at least one selected from the group consisting of dysprosium (Dy), manganese (Mn), vanadium (V), silicon (Si), and aluminum (Al).

[0018] The subcomponent may further include at least one selected from the group consisting of magnesium (Mg), tin (Sn), antimony (Sb), germanium (Ge), gallium (Ga), indium (In), lanthanum (La), chromium (Cr), hafnium (Hf), yttrium (Y), actinium (Ac), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

[0019] The Dy, Mn, V, Si and Al in the auxiliary components can be respectively 2 O 3 、MnO 2 、V2 O 5 、SiO 2 、Al 2 O 3 In the form of, relative to 100 mol parts of the main component, 0.5 mol parts to 1.5 mol parts of Dy can be added. 2 O 3 , 0.05 to 0.15 mol parts of MnO 2 , 0.05 to 0.15 mol parts of V 2 O 5 , 0.5 to 1.0 mol parts of SiO 2 or 0.2 to 1.0 mol parts of Al 2 O 3 The auxiliary components may also include BaCO 3 Ba is added in the form of BaCO, and 1.0 to 2.5 mol parts of BaCO are added relative to 100 mol parts of the main component. 3 .

[0020] The shell may include greater than 0.1 mol parts and less than or equal to 30.0 mol parts of the subcomponent relative to 100 mol parts of the main component, and the core may include less than or equal to 0.1 mol parts of the subcomponent relative to 100 mol parts of the main component.

[0021] The average diameter of the core may be from 50 nm to 500 nm.

[0022] The dielectric layer may have an average thickness of 0.15 μm to 10 μm.

[0023] A multilayer capacitor according to another embodiment may include: a capacitor body including a dielectric layer and an inner electrode; and an outer electrode disposed outside the capacitor body.

[0024] The dielectric layer includes a plurality of dielectric grains, and the plurality of dielectric grains contain barium titanate as a main component.

[0025] At least one dielectric grain among the plurality of dielectric grains has a core-shell structure including a core and a shell.

[0026] An average molar ratio of barium to titanium (Ba / Ti molar ratio) in the core of the at least one dielectric grain may be 0.9975 to 1.0055.

[0027] An average number of the cores per unit area (1 μm×1 μm) in the dielectric layer may be 27 to 35.

[0028] A ratio of an average area of ​​the shell included in the at least one dielectric grain having the core-shell structure to an average area of ​​the at least one dielectric grain having the core-shell structure may be 30% to 50%.

[0029] An average molar ratio of barium to titanium (Ba / Ti molar ratio) in the core of the at least one dielectric grain may be 0.9980 to 1.0050.

[0030] A ratio of an average area of ​​the shell included in the at least one dielectric grain having the core-shell structure to an average area of ​​the at least one dielectric grain having the core-shell structure may be 38% to 46%.

[0031] The main component may include BaTiO 3 、Ba(Ti,Zr)O 3 、Ba(Ti,Sn)O 3 、(Ba,Ca)TiO 3 、(Ba,Ca)(Ti,Zr)O 3 、(Ba,Ca)(Ti,Sn)O 3 、(Ba,Sr)TiO 3 、(Ba,Sr)(Ti,Zr)O 3 and (Ba,Sr)(Ti,Sn)O 3 At least one of the group consisting of.

[0032] The dielectric grains may further include secondary components.

[0033] The subcomponent may include at least one selected from the group consisting of dysprosium (Dy), manganese (Mn), vanadium (V), silicon (Si), and (Al).

[0034] The Dy, Mn, V, Si and Al in the auxiliary components can be respectively 2 O 3 、MnO 2 、V 2 O 5 、SiO 2 、Al 2 O 3 In the form of addition, 0.5 to 1.5 mol parts of Dy can be added relative to 100 mol parts of the main component. 2 O 3 , 0.05 to 0.15 mol parts of MnO 2 , 0.05 to 0.15 mol parts of V 2 O 5 , 0.5 to 1.0 mol parts of SiO 2or 0.2 to 1.0 mol parts of Al 2 O 3 The auxiliary components may also include BaCO 3 Ba is added in the form of BaCO, and 1.0 to 2.5 mol parts of BaCO are added relative to 100 mol parts of the main component. 3 .

[0035] The shell may include greater than 0.1 mol parts and less than or equal to 30.0 mol parts of the subcomponent relative to 100 mol parts of the main component, and the core may include less than or equal to 0.1 mol parts of the subcomponent relative to 100 mol parts of the main component.

[0036] The average diameter of the core may be from 50 nm to 500 nm.

[0037] The dielectric layer may have an average thickness of 0.15 μm to 10 μm.

[0038] Based on the multilayer capacitor according to some embodiments, a multilayer capacitor having a very excellent dielectric constant can be provided by controlling the average Ba / Ti molar ratio of the main components in the core of the dielectric grains and / or the average area ratio of the shells of the dielectric grains. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a perspective view showing a multilayer capacitor according to an embodiment.

[0040] Figure 2 is along Figure 1 A cross-sectional view of the multilayer capacitor taken along line II'.

[0041] Figure 3 It is shown Figure 1 An exploded perspective view of the stacked structure of the inner electrode layers in the capacitor body.

[0042] Figure 4 is a diagram schematically showing the composition of dielectric grains in a dielectric layer.

[0043] Figure 5 This is an image based on TEM mapping of the subcomponent Dy, which is a result of component analysis within a unit area (1 μm×1 μm) of the dielectric layer of the multilayer capacitor in Example 3.

[0044] Figure 6 It is shown Figure 5 The image of the nucleus in .

[0045] Figure 7 is a SEM image obtained by observing dielectric grains of a dielectric layer included in the multilayer capacitor of Example 3 using a scanning electron microscope (SEM).

[0046] Figure 8 The results of TEM image analysis of the multilayer capacitor of Example 3 are shown. DETAILED DESCRIPTION

[0047] Hereinafter, the present disclosure will be described in detail with reference to the accompanying drawings, in which embodiments of the present disclosure are shown. The drawings and descriptions are considered to be illustrative rather than restrictive in nature. Throughout the specification, the same reference numerals represent the same elements. The drawings are intended only to facilitate the understanding of the embodiments disclosed in this specification, and it should be understood that the technical ideas disclosed herein are not limited by the drawings and include all variations, equivalents or alternatives within the scope of the ideas and techniques of the present disclosure.

[0048] Although the terms "first", "second", etc. are used to explain various constituent elements, the constituent elements are not limited to these terms. These terms are only used to distinguish one constituent element from another constituent element.

[0049] When it is mentioned that a certain component is "coupled" or "connected" to another component, it is understood that although the component can be directly coupled or connected to another component, other components may exist between the two components. In addition, when it is mentioned that a certain component is "directly coupled" or "directly connected" to another component, it must be understood that there are no other components between the two components.

[0050] Throughout the specification, the terms "include" or "have" are intended to specify the presence of the features, integers, steps, operations, constituent elements, components and / or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, operations, constituent elements, components and / or groups thereof. Therefore, unless explicitly described to the contrary, the term "include" and variations such as "comprises" or "have" will be understood to imply the inclusion of the elements stated but not the exclusion of any other elements.

[0051] Figure 1 is a perspective view showing a multilayer capacitor 100 according to an embodiment, Figure 2 is along Figure 1 A cross-sectional view of the multilayer capacitor 100 taken along line II', Figure 3 It is shown Figure 1 An exploded perspective view of a stacked structure of inner electrode layers (ie, inner electrodes) in a capacitor body 110.

[0052] When defining directions to clearly explain the present embodiment, the L-axis direction, W-axis direction, and T-axis direction shown in the drawings represent the length direction, width direction, and thickness direction of the capacitor body 110, respectively. Here, the thickness direction (T-axis direction) may be a direction perpendicular to the wide surface (main surface) of the sheet component, and may be used as the same concept as the stacking direction of the stacked dielectric layer 111, for example. The length direction (L-axis direction) may be a direction extending parallel to the wide surface (main surface) of the sheet component, and may be approximately perpendicular to the thickness direction (T-axis direction). For example, the length direction (L-axis direction) may be a direction along which the first external electrode 131 and the second external electrode 132 are relative to each other. The width direction (W-axis direction) may be a direction extending parallel to the wide surface (main surface) of the sheet component, and may be approximately perpendicular to the thickness direction (T-axis direction) and the length direction (L-axis direction). The length of the sheet component in the length direction (L-axis direction) may be longer than the length in the width direction (W-axis direction).

[0053] Reference Figures 1 to 3 , the multilayer capacitor 100 according to an embodiment of the present disclosure may include a capacitor body 110 and first and second external electrodes 131 and 132 disposed at opposite ends of the capacitor body 110 in a length direction (L-axis direction).

[0054] For example, the capacitor body 110 may have a substantially hexahedral shape.

[0055] For the convenience of describing the present embodiment, the two surfaces opposite to each other in the thickness direction (T-axis direction) of the capacitor body 110 are referred to as the first surface and the second surface, the two surfaces connected to the first surface and the second surface and opposite to each other in the length direction (L-axis direction) are referred to as the third surface and the fourth surface, and the two surfaces connected to the first surface and the second surface, connected to the third surface and the fourth surface and opposite to each other in the width direction (W-axis direction) are referred to as the fifth surface and the sixth surface.

[0056] For example, the first surface as the lower surface may be a mounting surface. In addition, the first to sixth surfaces may be flat, but the embodiment is not limited thereto. For example, the first to sixth surfaces may be curved surfaces having a convex central portion, and the edge as the boundary of each surface may be rounded.

[0057] The shape and size of the capacitor body 110 and the number of stacks of the dielectric layers 111 are not limited to those shown in the drawings of the embodiment.

[0058] The capacitor body 110 includes a plurality of dielectric layers 111 stacked in a thickness direction (T-axis direction), and includes first internal electrodes 121 and second internal electrodes 122 alternately arranged in the thickness direction (T-axis direction), and the dielectric layer 111 is interposed between the first internal electrodes 121 and the second internal electrodes 122.

[0059] At this time, adjacent dielectric layers 111 of the capacitor body 110 may be integrated to such an extent that it is difficult to inspect a boundary therebetween without using a scanning electron microscope (SEM).

[0060] Additionally, capacitor body 110 may include an active area and footprints 112 and 113 .

[0061] The active region is a portion that contributes to forming the capacitance of the multilayer capacitor 100. For example, the active region may be a region where the first and second internal electrodes 121 and 122 stacked in the thickness direction (T-axis direction) overlap.

[0062] The covering regions 112 and 113 are thickness-direction edge portions and may be located on the upper and lower surfaces of the active region in the thickness direction (T-axis direction), respectively. These covering 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.

[0063] In addition, the capacitor body 110 may further include a side covering area. The side covering area is a width direction edge portion and may be respectively located on two side surfaces (close to the fifth surface and the sixth surface of the capacitor body 110) of the effective area in the width direction (W-axis direction). The side covering area may be formed by the following method: when a conductive paste layer for an internal electrode layer is applied on the surface of a dielectric green sheet, the conductive paste layer is applied only on a portion of the surface of the dielectric green sheet, and the conductive paste layer is not applied on both sides of the surface of the dielectric green sheet in the width direction, and then the dielectric green sheets are stacked to form a stacked body and the stacked body is sintered.

[0064] The cover regions 112 and 113 and the side cover regions serve to prevent the first and second internal electrodes 121 and 122 from being damaged due to physical stress or chemical stress.

[0065] Figure 4 1 is a diagram schematically showing the composition of dielectric grains 1111 in the dielectric layer. Figure 4 The dielectric grains 1111 are described in detail.

[0066] The dielectric layer 111 includes a plurality of dielectric grains 1111 .

[0067] The dielectric crystal grains 1111 include barium titanate as a main component. The main component is a dielectric base material, which has a high dielectric constant and contributes to forming the dielectric constant of the multilayer capacitor 100.

[0068] For example, the main component may be a dielectric material, and the dielectric material includes at least one selected from the group consisting of Ba m TiO 3 (0.995 ≤ m ≤ 1.010), (Ba 1-x Ca x ) m (Ti 1-y Zr y )O 3 (0.995 ≤ m ≤ 1.010, 0 ≤ x ≤ 0.10, 0 < y ≤ 0.20), Ba m (Ti 1-x Zr x )O 3 (0.995 ≤ m ≤ 1.010, 0 < x ≤ 0.10), and (Ba 1-x Ca x ) m (Ti 1-y Sn y )O 3 (0.995 ≤ m ≤ 1.010, 0 ≤ x ≤ 0.10, 0 < y ≤ 0.20).

[0069] For example, the main component may include at least one selected from the group consisting of BaTiO 3 , Ba(Ti,Zr)O 3 , Ba(Ti,Sn)O 3 , (Ba,Ca)TiO 3 , (Ba,Ca)(Ti,Zr)O 3 , (Ba,Ca)(Ti,Sn)O 3 , (Ba,Sr)TiO 3 , (Ba,Sr)(Ti,Zr)O 3 , and (Ba,Sr)(Ti,Sn)O 3 .

[0070] The dielectric grains 1111 may further include secondary components together with the main component.

[0071] The secondary components may include at least one selected from the group consisting of dysprosium (Dy), manganese (Mn), vanadium (V), silicon (Si), aluminum (Al), and barium (Ba).

[0072] In addition, the subcomponents may also include at least one selected from the group consisting of magnesium (Mg), tin (Sn), antimony (Sb), germanium (Ge), gallium (Ga), indium (In), lanthanum (La), chromium (Cr), hafnium (Hf), yttrium (Y), actinium (Ac), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu).

[0073] For example, Dy, Mn, V, Ba, Si, and Al in the auxiliary components are respectively 2 O 3 、MnO 2 、V 2 O 5 、BaCO 3 、SiO 2 and Al 2 O 3 In the form of adding, with respect to 100 mol parts of the main component, 0.5 mol parts to 1.5 mol parts of Dy 2 O 3 , 0.05 to 0.15 mol parts of MnO 2 , 0.05 to 0.15 mol parts of V 2 O 5 , 1.0 to 2.5 mol parts of BaCO 3 , 0.5 to 1.0 mol parts of SiO 2 or 0.2 to 1.0 mol parts of Al 2 O 3 .

[0074] In the dielectric grains 1111, there may be a portion in which the molar ratio of the auxiliary component to the main component is different. For example, at least one of the plurality of dielectric grains 1111 has a core-shell structure including a core and a shell. The dielectric grain 1111 having the core-shell structure includes a core 1111a and a shell 1111b surrounding at least a portion of the core 1111a in one dielectric grain 1111.

[0075] The molar ratio of the secondary component to the main component of the core 1111a and the shell 1111b is different. For example, the molar ratio of the secondary component to the main component can change rapidly at the boundary between the core 1111a and the shell 1111b. Therefore, the boundary between the core 1111a and the shell 1111b can be easily distinguished, and this can be seen by transmission electron microscopy-energy dispersive X-ray analysis (TEM-EDX).

[0076] For example, in a cross section cut from the center of the capacitor body 110 in the W-axis direction along the L-axis direction and the T-axis direction, when a line analysis is performed using an energy dispersive X-ray spectrometer (EDS) installed in a transmission electron microscope (TEM) on the dielectric grain 1111 located at the center of the effective area from the center of the core 1111a of the dielectric grain 1111 along the direction of the grain boundary on either side of the dielectric grain 1111, the core 1111a and the shell 1111b can be distinguished by using a portion where the total content of the subcomponents may begin to increase rapidly as the boundary between the core 1111a and the shell 1111b.

[0077] Here, the center of the core 1111a may be determined as a point where the longest major axis of the core 1111a and the shortest of the short axes orthogonal thereto intersect. In addition, an energy dispersive X-ray spectrometer (EDS) line analysis may be performed along the longest principal axis passing through the center of the core 1111a of the dielectric grain 1111. Alternatively, the boundary or grain boundary between the core 1111a and the shell 1111b may be defined by distinguishing portions having a contrast difference, such as by binarizing a transmission electron microscope image.

[0078] For example, the core 1111a may contain less than or equal to 0.1 mol parts of the secondary component relative to 100 mol parts of the main component, and the shell 1111b may contain greater than 0.1 mol parts and less than or equal to 30.0 mol parts of the secondary component, or greater than 0.1 mol parts and less than or equal to 20.0 mol parts of the secondary component relative to 100 mol parts of the main component.

[0079] If the core 1111a includes more than 0.1 mol parts of the auxiliary component relative to 100 mol parts of the main component, a pure dielectric material (e.g., BaTiO 3 ) may change. If the shell 1111b contains less than or equal to 0.1 mol parts of the auxiliary component relative to 100 mol parts of the main component, the range of change of the dielectric constant with temperature may increase. If the shell 1111b contains more than 30.0 mol parts of the auxiliary component relative to 100 mol parts of the main component, the initial insulation resistance may decrease.

[0080] That is, the secondary component may not exist in the core 1111a, or if it exists, it may exist only in a trace amount. Therefore, the core 1111a may be composed of only a pure primary component without containing impurities, and the pure primary component may generally have a higher dielectric constant than the primary component doped with impurity elements. Therefore, the core 1111a may play a role in maintaining the dielectric constant.

[0081] The shell 1111b contains more secondary components than the core 1111a. In the shell 1111b, the primary component (perovskite ABO 3The auxiliary component doped at the B site of the main component (perovskite ABO) has the effect of increasing the band gap energy, through which other rare earth elements and doping elements diffuse into the dielectric grains 1111. 3 The subcomponent doped at the B site of the dielectric structure) can serve as a barrier layer to prevent other rare earth elements and doping elements from diffusing into the dielectric grains 1111.

[0082] The shell 1111b may play a role in suppressing the growth of the dielectric grains 1111 and facilitating the micronization of the dielectric grains 1111. In addition, the subcomponent doped at the A site of the main component in the shell 1111b may play a role in improving reliability and dielectric constant.

[0083] The dielectric grains 1111 have an average molar ratio of barium to titanium (Ba / Ti molar ratio) of 0.9975 to 1.0055 in the cores 1111a of the dielectric grains. For example, the average molar ratio of barium to titanium (Ba / Ti molar ratio) in the cores 1111a of the dielectric grains may be 0.9980 to 1.0050. If the average molar ratio of barium to titanium (Ba / Ti molar ratio) in the cores 1111a of the dielectric grains is less than 0.9975 or greater than 1.0055, the dielectric constant of the capacitor may be reduced.

[0084] Nano-XRF (e.g., nano-synchrotron X-ray fluorescence (nano-SXRF)) can be used to measure the composition of specific elements (e.g., Ba and Ti) in the core 1111a of the dielectric grain. At this time, the measurement equipment can use the ID16A-NI (UPBL04) product from ESRF (European Synchrotron Radiation Source).

[0085] For example, after the multilayer capacitor 100 is placed in an epoxy resin mixture and cured, the sides of the capacitor body 110 in the L-axis direction and the T-axis direction are polished to a point halfway in the W-axis direction, fixed and maintained in a vacuum atmosphere chamber, thereby preparing a cross-sectional sample cut from the center of the capacitor body 110 in the W-axis direction along the L-axis direction and the T-axis direction.

[0086] By irradiating a cross-sectional sample of the prepared capacitor body 110 with synchrotron radiation X-rays (10 keV or higher), the content of a specific element (e.g., Ba and Ti) in the core 1111a of the dielectric grain can be measured three times to obtain an average value, and the average value of the minimum and maximum values ​​measured in at least 10 different dielectric grains located in the same dielectric layer can be used as the final content of the specific element.

[0087] For example, when at least 10 different dielectric grains located in the same dielectric layer are selected, they may be selected from a scanning electron microscope (SEM) image obtained by observing dielectric grains of the dielectric layer 111 located in the center of the active area with SEM.

[0088] The ratio of the average area of ​​the shell 1111b included in the at least one dielectric grain 1111 having the core-shell structure to the average area of ​​the at least one dielectric grain 1111 having the core-shell structure (i.e., the average area ratio of the shell 1111b included in the at least one dielectric grain 1111) may be 30% to 50%, for example, 35% to 50%, 35% to 46%, or 38% to 46%. If the average area ratio of the shell 1111b included in the at least one dielectric grain 1111 is less than 30% or greater than 50%, the dielectric constant of the capacitor may be reduced.

[0089] An average area ratio of the shells 1111 b included in the at least one dielectric grain 1111 having the core-shell structure may be measured by the following method.

[0090] The L-axis and T-axis surfaces (fifth surface or sixth surface) of the capacitor body 110 are polished along the W-axis direction until the dielectric layer 111 is exposed to, for example, a point of approximately half, the dielectric layer 111 can be exposed in the cross-sections in the L-axis and T-axis directions, a random dielectric layer 111 is selected from the cross-sections in the L-axis and T-axis directions, and an area of ​​1 μm×1 μm size (unit area) in the effective area is used as a measurement target.

[0091] Alternatively, the L-axis direction and W-axis direction surfaces (first surface or second surface) of the capacitor body 110 may be polished along the T-axis direction until the dielectric layer 111 is exposed to, for example, about half of the point, the dielectric layer 111 may be exposed in the cross-section in the L-axis direction and the W-axis direction, and an area of ​​1 μm×1 μm size (unit area) in the effective area may be taken as a measurement target. The unit area is set to an area containing at least one dielectric grain having a core-shell structure.

[0092] For the measurement target, the diameter and area of ​​one dielectric grain 1111 are measured using TEM under the conditions of an acceleration voltage of 200 kV and a WD (working distance) of 115 mm. At this time, the diameter of one dielectric grain 1111 can be calculated as the average value of the longest major axis and the shortest minor axis orthogonal thereto, and the area of ​​one dielectric grain 1111 can be calculated using the diameter assuming that the dielectric grain 1111 is a circle.

[0093] In addition, for the measurement target, the diameter of the core 1111a, the area of ​​the core 1111a, and the area of ​​the shell 1111b were measured in the following manner: the composition and element distribution of one dielectric grain 1111 were measured under the conditions of an acceleration voltage of 200 kV, a WD of 115 mm, and a mapping scan (dwell time) of 30 μs using an energy dispersive X-ray spectrometer (EDS) mounted on a transmission electron microscope (TEM) to distinguish the core 1111a from the shell 1111b.

[0094] At this time, the diameter of the core 1111a can be calculated as the average of the major axis and the minor axis orthogonal thereto, and the area of ​​the core 1111a can be calculated using the diameter assuming that the core 1111a is a circle. In addition, the area of ​​the shell 1111b can be calculated by subtracting the area of ​​the core 1111a from the area of ​​the dielectric grain 1111.

[0095] In addition, the average values ​​of the measured diameter of the dielectric grain 1111, the diameter of the core 1111a, the area of ​​the dielectric grain 1111, the area of ​​the core 1111a and the area of ​​the shell 1111b can be the arithmetic mean of three corresponding values ​​of the dielectric grain 1111 measured in three different layers in the dielectric layer 111 on the L-axis direction and the T-axis direction cross-section, or the arithmetic mean of nine corresponding values ​​of the dielectric grain 1111 measured at the center, one end and the other end of the effective area in three different layers in the dielectric layer 111 on the L-axis direction and the T-axis direction cross-section obtained above.

[0096] The average number of cores 1111a per unit area (1 μm×1 μm) of the dielectric layer 111 is 25 to 35. For example, the average number of cores 1111a per unit area (1 μm×1 μm) of the dielectric layer 111 may be 27 to 35. If the average number of cores 1111a per unit area (1 μm×1 μm) of the dielectric layer 111 is less than 25 or greater than 35, the dielectric constant of the capacitor may decrease.

[0097] Figure 5 is an image based on TEM mapping of the subcomponent Dy as a result of component analysis within a unit area (1 μm×1 μm) of the dielectric layer 111 of the multilayer capacitor according to the embodiment (Example 3), and Figure 6 It is shown Figure 5 The image of the core 1111a in FIG. Figure 6 , the number of cores 1111 a having an average diameter of about 50 nm or more can be measured within a unit area (1 μm×1 μm) of the dielectric layer 111 .

[0098] The average diameter of the dielectric grains 1111 having the core-shell structure may be 100 nm to 1000 nm, and the average diameter of the cores 1111 a included in the dielectric grains 1111 having the core-shell structure may be 50 nm to 500 nm.

[0099] For example, the average thickness of dielectric layer 111 may be 0.15 μm or more, 0.3 μm or more, 0.5 μm or more, 1.0 μm or more, or 2.0 μm or more, and the average thickness of dielectric layer 111 may be 10 μm or less, 8.0 μm or less, or 5.0 μm or less.

[0100] The average thickness of the dielectric layer 111 can be measured by the following method.

[0101] First, a scanning electron microscope image (hereinafter referred to as an SEM image) is obtained by observing a cross-sectional sample using a scanning electron microscope (SEM). Here, the surfaces (the fifth surface or the sixth surface) of the capacitor body 110 in the L-axis direction and the T-axis direction are polished along the W-axis direction until the dielectric layer 111 is exposed to, for example, about half of the point to obtain a cross-sectional sample, or the surfaces (the third surface or the fourth surface) of the capacitor body 110 in the T-axis direction and the W-axis direction are polished along the L-axis direction until the dielectric layer 111 is exposed to, for example, about half of the point to obtain a cross-sectional sample.

[0102] In the SEM image of the above cross-sectional sample, the arithmetic mean of the thicknesses of the dielectric layer 111 measured at 10 points spaced apart from a reference point by a predetermined interval can be regarded as the average thickness of the dielectric layer 111. The reference point is the center point in the L-axis direction or the W-axis direction of the dielectric layer 111.

[0103] The interval of the 10 points can be adjusted according to the scale of the SEM image. For example, it can be 1 μm to 100 μm, 1 μm to 50 μm, or 1 μm to 10 μm.

[0104] At this time, all 10 points must be located within the dielectric layer 111. 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 the 10 points can be adjusted.

[0105] The first internal electrode 121 and the second internal electrode 122 are electrodes with different polarities, which are alternately arranged opposite to each other along the T-axis direction. The dielectric layer 111 is interposed between the first internal electrode 121 and the second internal electrode 122, and one end of the first internal electrode 121 and one end of the second internal electrode 122 can be exposed through the third surface and the fourth surface of the capacitor body 110, respectively.

[0106] The first internal electrode 121 and the second internal electrode 122 can be electrically insulated from each other through the dielectric layer 111 provided between them.

[0107] The ends of the first internal electrode 121 and the second internal electrode 122 alternately exposed through the third surface and the fourth surface of the capacitor body 110 can be electrically connected to the first external electrode 131 and the second external electrode 132, respectively.

[0108] The first internal electrode 121 and the second internal electrode 122 can include a conductive metal. For example, metals such as Ni, Cu, Ag, Pd, Au or their alloys, such as Ag-Pd alloy.

[0109] In addition, the first and second internal electrodes 121 and 122 may include dielectric particles having the same composition as the ceramic material included in the dielectric layer 111 .

[0110] The first and second internal electrodes 121 and 122 may be formed using a conductive paste including a conductive metal. A printing method of the conductive paste may be a screen printing method or a gravure printing method.

[0111] For example, the average thickness of the first and second internal electrodes 121 and 122 may be 0.1 μm to 2 μm.

[0112] Similar to measuring the average thickness of the dielectric layer 111, in the above SEM image, the average thickness of the first internal electrode 121 and the second internal electrode 122 may be the arithmetic mean of the thickness of the first internal electrode 121 or the second internal electrode 122 at 10 points spaced apart from a reference point by a predetermined interval, and the reference point is the center point in the length direction (L-axis direction) or the width direction (W-axis direction) of the first internal electrode 121 or the second internal electrode 122. The interval of the 10 points may be adjusted according to the scale of the SEM image, for example, may be 1 μm to 100 μm, 1 μm to 50 μm, or 1 μm to 10 μm. At this time, all 10 points must be located within the first internal electrode 121 or the second internal electrode 122. If all 10 points are not located within the first internal electrode 121 or the second internal electrode 122, the position of the reference point may be changed, or the interval between the 10 points may be adjusted.

[0113] The first and second external electrodes 131 and 132 are supplied with voltages of different polarities and may be electrically connected to exposed portions of the first and second internal electrodes 121 and 122 , respectively.

[0114] According to 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 and second internal electrodes 121 and 122. At this time, the capacitance of the multilayer capacitor 100 is proportional to the overlapping area where the first and second internal electrodes 121 and 122 overlap each other in the T-axis direction in the active region.

[0115] The first outer electrode 131 may include a first connection portion arranged on the third surface of the capacitor body 110 to be connected to the first inner electrode 121, and a first band portion arranged at a corner where the third surface of the capacitor body 110 intersects with the first surface, the second surface, the fifth surface and the sixth surface, and the second outer electrode 132 may include a second connection portion arranged on the fourth surface of the capacitor body 110 to be connected to the second inner electrode 122, and a second band portion arranged at a corner where the fourth surface of the capacitor body 110 intersects with the first surface, the second surface, the fifth surface and the sixth surface.

[0116] The first band portion may extend from the first connection portion to a portion of the first and second surfaces of the capacitor body 110, and may further extend from the first connection portion to a portion of the fifth and sixth surfaces of the capacitor body 110, and the second band portion may extend from the second connection portion to a portion of the first and second surfaces of the capacitor body 110, and may further extend from the second connection portion to a portion of the fifth and sixth surfaces of the capacitor body 110. The first band portion and the second band portion may be used to improve the bonding strength between the first and second external electrodes 131 and 132 and the capacitor body 110.

[0117] For example, the first and second external electrodes 131 and 132 may each include a sintered metal layer contacting the capacitor body 110 , a conductive resin layer disposed to cover the sintered metal layer, and a plated layer disposed to cover the conductive resin layer.

[0118] The sintered metal layer may include conductive metal and glass.

[0119] For example, the sintered metal layer may include a conductive metal such as at least one selected from the group consisting of copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), gold (Au), platinum (Pt), tin (Sn), tungsten (W), titanium (Ti), lead (Pb), alloys thereof, and combinations thereof. For example, the conductive metal including copper (Cu) may mean that the conductive metal includes a copper (Cu) element or includes a copper (Cu) alloy. When the conductive metal includes copper, other metals other than copper may be included in an amount of 5 mol parts or less based on 100 mol parts of copper.

[0120] For example, the sintered metal layer may include a composition of mixed oxides, such as glass. For example, the sintered metal layer may include one or more selected from the group consisting of silicon oxide, boron oxide, aluminum oxide, transition metal oxides, alkali metal oxides, and alkaline earth metal oxides. The transition metal may include at least one selected from the group consisting of zinc (Zn), titanium (Ti), copper (Cu), vanadium (V), manganese (Mn), iron (Fe), and nickel (Ni). The alkali metal may include at least one selected from the group consisting of lithium (Li), sodium (Na), and potassium (K). The alkaline earth metal may include one or more selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

[0121] Alternatively, the conductive resin layer is formed on the sintered metal layer, for example, may be formed to completely cover the sintered metal layer. In addition, the first external electrode 131 and the second external electrode 132 may not include the sintered metal layer. In this case, the conductive resin layer may be in direct contact with the capacitor body 110.

[0122] The conductive resin layer extends to the first surface and the second surface of the capacitor body 110, and may also extend to the fifth surface and the sixth surface of the capacitor body 110. Moreover, the length of the region (i.e., the belt portion) where the conductive resin layer extends and is disposed on the first surface and the second surface and / or the fifth surface and the sixth surface of the capacitor body 110 may be longer than the length of the region (i.e., the belt portion) where the sintered metal layer extends and is disposed on the first surface and the second surface and / or the fifth surface and the sixth surface of the capacitor body 110. In other words, the conductive resin layer may be formed on the sintered metal layer and may be formed to completely cover the sintered metal layer.

[0123] The conductive resin layer may include a resin and a conductive metal.

[0124] The resin included in the conductive resin layer may be realized by a material having adhesiveness and shock-absorbing properties and capable of forming a paste when mixed with conductive metal powder, but is not limited thereto. For example, the resin may include a phenolic resin, an acrylic resin, a silicone resin, an epoxy resin, or a polyimide resin.

[0125] The conductive metal included in the conductive resin layer can be used for electrically connecting the first internal electrode 121 or the second internal electrode 122 or for electrically connecting the sintered metal layer.

[0126] The conductive metal included in the conductive resin layer may have a spherical shape, a flake shape, or a combination thereof. That is, the conductive metal may be formed only in the form of flakes, only in the form of spheres, or in a mixed form of flakes and spheres.

[0127] Here, the spherical shape may also include a shape that is not a perfect spherical shape. For example, a shape having a length ratio of the major axis to the minor axis (major axis / minor axis) of 1.45 or less. The flake shape refers to a shape having a flat and elongated shape and is not particularly limited. However, for example, the length ratio of the major axis to the minor axis (major axis / minor axis) may be 1.95 or more.

[0128] The first external electrode 131 and the second external electrode 132 may also include a plating layer disposed outside the conductive resin layer.

[0129] The plating layer may include at least one selected from the group consisting of nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), gold (Au), silver (Ag), tungsten (W), titanium (Ti), and lead (Pb) and their alloys. For example, the plating layer may include a nickel (Ni) plating layer or a tin (Sn) plating layer, may be in the form of a nickel (Ni) plating layer and a tin (Sn) plating layer stacked in sequence, or may be in the form of a tin (Sn) plating layer, a nickel (Ni) plating layer, and a tin (Sn) plating layer stacked in sequence. Additionally, the plating layer may include multiple nickel (Ni) plating layers and / or multiple tin (Sn) plating layers.

[0130] The plating layer may improve the mountability to a substrate, structural reliability, durability to the outside, heat resistance, and equivalent series resistance (ESR) of the multilayer capacitor 100 .

[0131] A method of preparing a multilayer capacitor includes: preparing a dielectric powder; preparing a capacitor body including a dielectric layer and an inner electrode; and forming an outer electrode on an outer side of the capacitor body.

[0132] First, a method of preparing dielectric powder will be described.

[0133] A barium (Ba) precursor and a titanium (Ti) precursor are wet-mixed and the amount of the barium (Ba) precursor or the titanium (Ti) precursor added is adjusted so that the molar ratio of barium to titanium (Ba / Ti molar ratio) is 0.9975 to 1.0055. Thus, a barium titanate powder having a uniform molar ratio of barium to titanium can be prepared, and by using the barium titanate powder to form a dielectric layer, reliability characteristics can be improved by forming dielectric grains having a uniform molar ratio of barium to titanium.

[0134] The barium (Ba) precursor may include BaO 2 、BaTiO 3 、BaCO 3 , BaO or a combination thereof.

[0135] The titanium (Ti) precursor may be an oxide, salt or alkoxide of titanium, for example, titanium dioxide (TiO 2 ), diisopropoxy diacetylacetonate titanium (TPA), titanium alkoxide or a combination thereof.

[0136] At this time, if the dielectric powder further contains additional elements such as Ca, Sr, Sn or Zr, the precursors of these additional elements may be further added together with the barium (Ba) precursor and the titanium (Ti) precursor. For example, the precursors of the additional elements may be compounds such as oxides or carbonates containing these additional elements.

[0137] For example, the raw material mixture can be wet mixed with the solvent by using a disperser such as a bead mill or a ball mill, or by high pressure dispersion treatment. For example, when a bead mill is used for dispersion, beads having a diameter of 0.03 mm to 0.1 mm can be dispersed 5 to 30 times at a peripheral speed of 5 m / s to 15 m / s.

[0138] The solvent used for wet mixing may include, for example, an aqueous solvent (such as ion-exchanged water, pure water, ultrapure water, or distilled water), or an amine solvent (such as ammonia or an organic amine), an alcohol solvent combined with water.

[0139] Optionally, a dispersant may be further added in the raw material mixing step, and the dispersant may include, for example, polyvinyl butyral dispersants, polyvinyl acetal dispersants, polycarboxylic acid dispersants, maleic acid dispersants, polyethylene glycol dispersants, allyl ether copolymer dispersants, and the like.

[0140] Alternatively, the feedstock mixture may be dried and dry ground.

[0141] Next, the raw material mixture is calcined to prepare a dielectric powder.

[0142] The calcination may be performed at 800° C. to 1000° C. for 1 to 8 hours, or at 840° C. to 900° C. for 2 to 6 hours.

[0143] The calcination may be performed in a vacuum atmosphere or an atmospheric pressure atmosphere, for example, the calcination may be performed at an atmospheric pressure of 10,000 Pa to 1,000,000 Pa. The vacuum atmosphere may be, for example, a vacuum atmosphere of 20,000 Pa or less, or 100 Pa or less.

[0144] If the calcination temperature is less than 800°C or the calcination time is less than 1 hour, problems of non-reaction and dispersibility may occur. If the calcination temperature is greater than 1000°C or the calcination time is greater than 8 hours, a coarse powder may be synthesized.

[0145] Alternatively, the dielectric powder may be wet ground and then dried and dry ground.

[0146] Next, the production of the capacitor main body will be described.

[0147] In the manufacturing process of the capacitor body, a dielectric paste that becomes a dielectric layer after firing and a conductive paste that becomes an internal electrode after firing are prepared.

[0148] In some embodiments, the dielectric paste is prepared according to the following method. The prepared dielectric powder is uniformly mixed by, for example, wet mixing, dried, and then heat-treated under predetermined conditions to obtain a calcined powder. An organic vehicle or an aqueous vehicle is added to the obtained calcined powder and kneaded to prepare a dielectric paste.

[0149] The dielectric green sheet is obtained by forming the obtained dielectric paste into a sheet using a technique such as a doctor blade method. In addition, if necessary, the dielectric paste may contain an additive selected from various dispersants, plasticizers, dielectrics, subcomponent compounds or glass.

[0150] The conductive paste for the inner electrode is prepared by mixing a conductive powder made of a conductive metal or its alloy with a binder or a solvent. If necessary, the conductive paste for the inner electrode may contain ceramic particles (e.g., barium titanate) as a co-material. The co-material may be used to suppress sintering of the conductive powder during the firing process.

[0151] Using various printing methods (such as screen printing) or transfer methods, a conductive paste for an internal electrode is coated onto the surface of a dielectric green sheet in a predetermined pattern. Then, a dielectric green sheet stack structure is prepared by stacking multiple dielectric green sheets on which internal electrode patterns are formed, and then pressing the multiple dielectric green sheets in the stacking direction. At this time, the dielectric green sheets can be stacked such that the dielectric green sheets are located on the upper surface and the lower surface of the dielectric green sheet stack structure in the stacking direction.

[0152] Optionally, the obtained dielectric green sheet stack structure can be cut into a predetermined size by cutting or the like.

[0153] In addition, if necessary, the dielectric green sheet stack structure can be cured and dried to remove plasticizers and the like, and after curing and drying, the dielectric green sheet stack structure can be barrel polished using a horizontal centrifugal barrel machine or the like. In barrel polishing, the dielectric green sheet stack structure is placed in a barrel container having a medium and a polishing liquid, and a rotational motion or vibration is applied to the barrel container, so that unnecessary parts such as burrs generated during cutting can be polished. In addition, after barrel polishing, the dielectric green sheet stack structure can be cleaned with a cleaning solution such as water and dried.

[0154] A capacitor body is obtained after performing an adhesive removal treatment and firing on the dielectric green sheet stack structure.

[0155] The conditions for adhesive removal can be appropriately adjusted according to the main components of the dielectric layer or the internal electrode layer. For example, the temperature increase rate during the adhesive removal treatment can be 5 °C / hour to 300 °C / hour, the carrier temperature can be 180 °C to 400 °C, and the temperature holding time can be 0.5 hour to 24 hours. The treatment atmosphere for adhesive removal can be air or a reducing atmosphere.

[0156] The conditions for firing can be appropriately adjusted according to the main components of the dielectric layer or the internal electrode layer. For example, the temperature during firing can be 1200 °C to 1350 °C, or 1220 °C to 1300 °C, and the time can be 0.5 hour to 8 hours, or 1 hour to 3 hours. The firing atmosphere can be a reducing atmosphere, for example, an atmosphere humidified with a mixed gas of nitrogen (N 2 ) and hydrogen (H 2 ). When the internal electrode includes nickel (Ni) or a nickel (Ni) alloy, the oxygen partial pressure in the firing atmosphere can be 1.0×10 -14 MPa to 1.0×10 -10 MPa.

[0157] After firing, annealing may be performed as needed. Annealing is a process for reoxidizing the dielectric layer, and annealing may be performed if firing is performed in a reducing atmosphere. The conditions of the annealing process may also be appropriately adjusted according to the main component composition of the dielectric layer. For example, the annealing temperature may be 950°C to 1150°C, the time may be 0 hours to 20 hours, and the temperature rise rate may be 50°C / hour to 500°C / hour. The annealing atmosphere may be humidified nitrogen (N 2 ) atmosphere, and the oxygen partial pressure may be 1.0×10 -9 MPa to 1.0×10 -5 MPa.

[0158] In the binder removal process, the firing process or the annealing process, for example, a wetting agent may be used to wet the nitrogen gas or the mixed gas. In this case, the wetting agent temperature may be 5° C. to 75° C. The binder removal process, the firing process and the annealing process may be performed sequentially or independently.

[0159] Optionally, the third and fourth surfaces of the obtained capacitor body 110 may be subjected to surface treatment such as sandblasting, laser irradiation, barrel polishing, etc. By performing the surface treatment, ends of the first and second internal electrodes may be exposed to the third and fourth surfaces, thereby improving electrical connection between the first external electrode and the first internal electrode and between the second external electrode and the second internal electrode.

[0160] A paste for forming a sintered metal layer may be applied on the outer surface of the obtained capacitor body and then sintered to form the sintered metal layer.

[0161] The paste for forming the sintered metal layer may include conductive metal and glass. Since the description of conductive metal and glass is the same as above, repeated description will be omitted. In addition, optionally, the paste for forming the sintered metal layer may include secondary components, such as, adhesive, solvent, dispersant, plasticizer or oxide powder. The adhesive may be, for example, ethyl cellulose, acrylic acid, butyral, etc., and the solvent may be, for example, an organic solvent or an aqueous solvent, such as, alcohol (for example, terpineol, butyl carbitol), methyl ethyl ketone, acetone, toluene, etc.

[0162] The method of applying the paste for forming the sintered metal layer on the outer surface of the capacitor body may include a dipping method, various printing methods such as screen printing, an application method using a dispenser, etc., and a spraying method using spraying. The paste for forming the sintered metal layer may be applied to at least the third and fourth surfaces of the capacitor body, and optionally, to portions of the first, second, fifth, and / or sixth surfaces on which the band portions of the first and second external electrodes are to be formed.

[0163] Thereafter, the capacitor body on which the paste for forming a sintered metal layer is applied 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.

[0164] Alternatively, a paste for forming a conductive resin layer may be applied to the outer surface of the obtained capacitor body and then cured to form the conductive resin layer.

[0165] The paste for forming the conductive resin layer may include resin and conductive metal, and optionally include non-conductive filler. Since the description of conductive metal and resin is the same as above, repeated description will be omitted. In addition, optionally, the paste for forming the conductive resin layer may include secondary components, such as, adhesive, solvent, dispersant, plasticizer or oxide powder. Adhesive may be, for example, ethyl cellulose, acrylic acid, butyral, etc., and solvent may be an organic solvent or an aqueous solvent, such as, alcohol (for example, terpineol, butyl carbitol), methyl ethyl ketone, acetone and toluene.

[0166] For example, the conductive resin layer may be formed by immersing the capacitor body 110 in a paste for forming the conductive resin layer and then curing it, or by printing the paste for forming the conductive resin layer on the surface of the capacitor body 110 by 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 curing it.

[0167] Next, a plating layer is formed on the outer side of the conductive resin layer.

[0168] For example, the plated layer can be formed by a plating method, a sputtering method, or an electrolytic plating (electrodeposition) method.

[0169] Hereinafter, detailed embodiments of the present disclosure will be described. However, the embodiments described below are only intended to specifically illustrate or explain the present disclosure, and the scope of the present disclosure should not be limited thereto.

[0170] (Preparation Example)

[0171] Preparation Example 1: Preparation of dielectric powder

[0172] Preparation of BaCO as a barium (Ba) precursor 3 Powder and TiO as a titanium (Ti) precursor 2 The powder was weighed and a powder having a content ratio as shown in Table 1 was prepared. 3 Powder and TiO 2 The powder was placed in a beaker, water was added thereto and wet mixed with a mixer. At this time, the BaCO 3 Powder and TiO 2The amount of powder added was adjusted to adjust the ratio of barium (Ba) and titanium (Ti) and the added BaCO was dispersed using a bead mill. 3 Powder and TiO 2 powder to prepare the raw material mixture.

[0173] The prepared raw material mixture is dried, and the agglomerated raw material mixture is dry-milled.

[0174] The dielectric powder was prepared by calcining the raw material mixture at 950° C. for 3 hours under atmospheric pressure.

[0175] After calcination, the agglomerated dielectric powder was wet-milled, dried, and the agglomerated dielectric powder was dry-milled again to obtain barium titanate powder.

[0176] (Table 1)

[0177] Classification Ba / Ti molar ratio in barium titanate powder Comparative Example 1 0.9970±0.0003 Example 1 0.9980±0.0003 Example 2 0.9990±0.0003 Example 3 1.0000±0.0003 Example 4 1.0010±0.0003 Example 5 1.0020±0.0003 Example 6 1.0030±0.0003 Example 7 1.0040±0.0003 Example 8 1.0050±0.0003 Comparative Example 2 1.0060±0.0003

[0178] Preparation Example 2: Preparation of multilayer capacitors

[0179] The barium titanate powder prepared in Preparation Example 1 was used as a main component of the dielectric base material, and the composition shown in Table 2 below was used as a subcomponent.

[0180] The main component powder and the auxiliary component powder of the dielectric matrix material are mixed with zirconium oxide balls (ZrO 2 A ball) is used, mixed with ethanol / toluene, a dispersant and a binder, and then mechanically ground to prepare a dielectric slurry.

[0181] The prepared dielectric slurry was used to prepare a dielectric green sheet using a roll die coater.

[0182] A conductive paste layer containing nickel (Ni) was printed on the surface of the dielectric green sheet, and the dielectric green sheets (width×length×height=3.2 mm×2.5 mm×2.5 mm) formed with the conductive paste layer were stacked and pressed to prepare a dielectric green sheet stack structure.

[0183] The binder removal treatment is carried out in a nitrogen atmosphere at 400°C or less, and then the sintering temperature is 1300°C or less in a 1.0% H 2 The dielectric green sheet stack structure was fired at a hydrogen concentration of 100 Å or less to manufacture the multilayer capacitors according to the examples and comparative examples.

[0184] (Table 2)

[0185] <![CDATA[BaTiO 3 ]]> <![CDATA[Dy 2 THE 3 ]]> <![CDATA[MnO 2 ]]> <![CDATA[V 2 THE 5 ]]> <![CDATA[BaCO 3 ]]> <![CDATA[SiO 2 ]]> <![CDATA[Al 2 THE 3 ]]> Comparative Example 1 1 0.1 0.1 1.5+0.9 0.75 0.5 Example 1 1 0.1 0.1 1.5+0.8 0.75 0.5 Example 2 1 0.1 0.1 1.5+0.7 0.75 0.5 Example 3 1 0.1 0.1 1.5+0.6 0.75 0.5 Example 4 1 0.1 0.1 1.5+0.5 0.75 0.5 Example 5 1 0.1 0.1 1.5+0.4 0.75 0.5 Example 6 1 0.1 0.1 1.5+0.3 0.75 0.5 Example 7 1 0.1 0.1 1.5+0.2 0.75 0.5 Example 8 1 0.1 0.1 1.5+0.1 0.75 0.5 Comparative Example 2 1 0.1 0.1 1.5 0.75 0.5

[0186] (Experimental example)

[0187] Experimental Example 1

[0188] The molar ratios of barium (Ba) and titanium (Ti) in the cores of the dielectric grains in the multilayer capacitors manufactured in the examples and comparative examples were measured, and the results are shown in Tables 3 and 4.

[0189] Ten multilayer capacitors in the examples and comparative examples were prepared respectively, the multilayer capacitors were placed in an epoxy resin mixture and cured, the sides of the capacitor body 110 in the L-axis direction and the T-axis direction were polished to the 1 / 2 point in the W-axis direction, and then fixed and maintained in a vacuum atmosphere chamber to obtain a cross-sectional sample of the capacitor body 110.

[0190] The obtained cross-sectional sample of the capacitor body 110 was analyzed by nano-synchrotron X-ray fluorescence (nano-SXRF) using European Synchrotron Radiation Source (ESRF) product ID16A-NI (UPB104).

[0191] At this time, the molar ratio of barium (Ba) and titanium (Ti) in the core of the dielectric grains was repeatedly measured three times by irradiation with synchrotron radiation X-rays (10 keV or higher), and the average value was calculated.

[0192] In addition, the average of the minimum and maximum values ​​measured from 10 different dielectric grains in the same dielectric layer is taken as the final molar ratio of barium (Ba) to titanium (Ti). Figure 7 3 is a SEM image obtained by observing dielectric grains of a dielectric layer included in the capacitor of Example 3 using a scanning electron microscope (SEM). Figure 7 As shown, 10 different dielectric grains located in the same dielectric layer can be selected.

[0193] exist Figure 7 The molar ratios of barium (Ba) and titanium (Ti) at 10 points selected are shown in Table 3.

[0194] In addition, the minimum value (Min.), the maximum value (Max.), and the average value (Avg.) of the molar ratio of barium (Ba) and titanium (Ti) at the center of the dielectric grains measured in Examples and Comparative Examples are shown in Table 4.

[0195] (Table 3)

[0196] Classification Ba / Ti molar ratio at the center of dielectric grains Point 1 0.9997 Point 2 0.9998 Point 3 1.0001 Point 4 0.9999 Point 5 1.0002 Point 6 1.0003 Point 7 1.0001 Point 8 1.0003 Point 9 0.9997 Point 10 1.0003

[0197] Referring to Table 3, it can be seen that the molar ratio of barium to titanium (Ba / Ti molar ratio) in the barium titanate powder in Example 3 of Table 1 is similar to the Ba / Ti molar ratio at the center of the dielectric grain in Table 3, and the error range is within ±0.0003.

[0198] (Table 4)

[0199]

[0200] Referring to Table 4, it can be seen that the multilayer capacitors manufactured in the examples had a molar ratio of barium to titanium (Ba / Ti molar ratio) of 0.9975 to 1.0055 at the center of the dielectric grain.

[0201] Experimental Example 2

[0202] The average area ratio of the shell included in the dielectric crystal grains having the core-shell structure of the multilayer capacitors manufactured in the examples and comparative examples was measured, and the results are shown in Table 5.

[0203] Ten multilayer capacitors in the examples and comparative examples were prepared respectively, and the L-axis and T-axis surfaces (fifth surface or sixth surface) of the capacitor body 110 were polished along the W-axis direction until the dielectric layer 111 was exposed to a point of, for example, approximately 1 / 2, and the dielectric layer 111 was exposed in the cross-sections in the L-axis and T-axis directions. Random dielectric layers 111 were selected from the cross-sections in the L-axis and T-axis directions, and an area of ​​1 μm×1 μm in size (unit area) in the effective area was used as a measurement target.

[0204] For the measurement target, TEM image analysis and EDS mapping component analysis were performed using a Cs-corrected scanning transmission electron microscope (Cs STEM) apparatus, which is a transmission electron microscope, under the condition of an accelerating voltage of 80 kV.

[0205] For example, Figure 8 The TEM image analysis results of the capacitor of Example 3 are shown, and Figure 5 This is an image based on TEM mapping of the subcomponent Dy within a unit area (1 μm×1 μm) of the dielectric layer 111 of the capacitor in Example 3.

[0206] The area of ​​the dielectric grain shell 1111 b was measured by TEM image analysis, and the range of the area ratio of the shell of three values ​​and the average area ratio of the shell measured in three different dielectric layers are shown in Table 5 below.

[0207] Through the above-mentioned TEM mapping analysis, the number of cores 1111a having an average diameter of about 50 nm or more was measured within a unit area (1 μm×1 μm) of the dielectric layer 111 and is shown in Table 5 below.

[0208] In addition, the dielectric constants of the multilayer capacitors manufactured in the examples and comparative examples were measured and the results are shown in Table 5.

[0209] 50 multilayer capacitors of the examples and comparative examples were prepared and measured using Keysight Technologies' E4980A product as an LCR meter under the conditions of 1 kHz and 1 V. The dielectric constant of the multilayer capacitor was calculated from the thickness of the dielectric layer, the area of ​​the inner electrode and the number of layers, and is shown in Table 5 below.

[0210] (Table 5)

[0211]

[0212] Referring to Table 5, in Examples 1 to 8, the average area ratio of the shells ranges from 30% to 50%, and the number of cores per unit area of ​​the dielectric layer is from 27 to 35. Therefore, it can be seen that the dielectric constant of the capacitor is realized to be 2000 or more.

[0213] Experimental Example 3

[0214] The breakdown voltage (BDV) of the multilayer capacitors manufactured in the examples and comparative examples was evaluated and the results are shown in Table 6.

[0215] 50 multilayer capacitors of the examples and comparative examples were prepared, and a voltage was applied from 0 V to 1100 V in increments of 1.00000 V using a Keithley 2410 meter by a sweep method, and the voltage value when the current value became 20 mA was measured as the BDV value. The BDV was measured in a silicone oil bath.

[0216] In addition, the high temperature stress reliability and moisture resistance reliability of the multilayer capacitors manufactured in the comparative example and the example were evaluated, and the results are shown in Table 7.

[0217] 40 multilayer capacitors in the examples and comparative examples were prepared and mounted on a measurement substrate, and the high temperature stress reliability was measured by HALT (Highly Accelerated Life Test) at 150°C, 150 hours, and 100 V using an ESPEC (PV-222, HALT) device. The moisture resistance reliability was measured at 85°C, relative humidity (RH) 85%, 32 V, and 24 hours using an ESPEC (PR-3J, 8585) device.

[0218] (Table 6)

[0219]

[0220] (Table 7)

[0221]

[0222]

[0223] Referring to Table 6 and Table 7, it can be seen that the examples have a dielectric constant of 2000 or more, and have dielectric loss factors and BDV values ​​similar to those of the comparative examples.

[0224] Furthermore, it can be seen that the examples have similar reliability to that of the comparative examples in terms of highly accelerated life test (HALT) and moisture resistance reliability.

[0225] While the present disclosure has been described in connection with what are presently considered to be practical embodiments, it should be understood that the present disclosure is not limited to the disclosed embodiments, but on the contrary is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0226] <Description of symbols>

[0227] 100: Multilayer capacitor

[0228] 110: Capacitor body

[0229] 111: Dielectric layer

[0230] 1111: Dielectric grains with core-shell structure

[0231] 1111a: Core of dielectric grain

[0232] 1111b: Shell of dielectric grains

[0233] 112, 113: Coverage area

[0234] 121: First inner electrode

[0235] 122: Second inner electrode

[0236] 131: First outer electrode

[0237] 132: Second external electrode.

Claims

1. A multilayer capacitor comprising: a capacitor body including a dielectric layer and inner electrodes; as well as An external electrode, disposed outside the capacitor body, The dielectric layer includes a plurality of dielectric grains, and the plurality of dielectric grains contain barium titanate as a main component. At least one dielectric grain among the plurality of dielectric grains has a core-shell structure including a core and a shell, An average molar ratio of barium to titanium in the core of the at least one dielectric grain is from 0.9975 to 1.0055, And the average number of cores per unit area in the dielectric layer is 25 to 35, and the unit area is 1 μm×1 μm.

2. The multilayer capacitor according to claim 1, wherein The average molar ratio of barium to titanium in the core of the at least one dielectric grain is from 0.9980 to 1.0050.

3. The multilayer capacitor according to claim 1, wherein A ratio of an average area of ​​the shell included in the at least one dielectric grain having the core-shell structure to an average area of ​​the at least one dielectric grain having the core-shell structure is 30% to 50%.

4. The multilayer capacitor according to claim 3, wherein A ratio of an average area of ​​the shell included in the at least one dielectric grain having the core-shell structure to an average area of ​​the at least one dielectric grain having the core-shell structure is 38% to 46%.

5. The multilayer capacitor according to claim 1, wherein The main component includes at least one selected from the group consisting of BaTiO3, Ba(Ti,Zr)O3, Ba(Ti,Sn)O3, (Ba,Ca)TiO3, (Ba,Ca)(Ti,Zr)O3, (Ba,Ca)(Ti,Sn)O3, (Ba,Sr)TiO3, (Ba,Sr)(Ti,Zr)O3 and (Ba,Sr)(Ti,Sn)O3.

6. The multilayer capacitor according to claim 1, wherein The dielectric grains further include a secondary component, and The subcomponent includes at least one selected from the group consisting of Dy, Mn, V, Si, and Al.

7. The multilayer capacitor of claim 6, wherein: The subcomponents also include at least one selected from the group consisting of Mg, Sn, Sb, Ge, Ga, In, La, Cr, Hf, Y, Ac, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Ho, Er, Tm, Yb and Lu.

8. The multilayer capacitor according to claim 6, wherein The Dy, Mn, V, Si and Al in the auxiliary components are added in the form of Dy2O3, MnO2, V2O5, SiO2 and Al2O3, respectively, and 0.5 to 1.5 mol parts of Dy2O3, 0.05 to 0.15 mol parts of MnO2, 0.05 to 0.15 mol parts of V2O5, 0.5 to 1.0 mol parts of SiO2 or 0.2 to 1.0 mol parts of Al2O3 are added relative to 100 mol parts of the main component, and The auxiliary component further includes Ba added in the form of BaCO 3 , and 1.0 to 2.5 parts by mole of BaCO 3 is added relative to 100 parts by mole of the main component.

9. The multilayer capacitor according to claim 6, wherein The shell includes greater than 0.1 mol parts and less than or equal to 30.0 mol parts of the secondary component relative to 100 mol parts of the primary component, and The core includes 0.1 mol parts or less of the subcomponent relative to 100 mol parts of the main component.

10. The multilayer capacitor according to claim 1, wherein The average diameter of the core is 50 nm to 500 nm.

11. The multilayer capacitor according to claim 1, wherein The dielectric layer has an average thickness of 0.15 μm to 10 μm.

12. A multilayer capacitor comprising: a capacitor body including a dielectric layer and inner electrodes; as well as An external electrode, disposed outside the capacitor body, The dielectric layer includes a plurality of dielectric grains, and the plurality of dielectric grains contain barium titanate as a main component. At least one dielectric grain among the plurality of dielectric grains has a core-shell structure including a core and a shell, An average molar ratio of barium to titanium in the core of the at least one dielectric grain is from 0.9975 to 1.0055, The average number of the cores per unit area in the dielectric layer is 27 to 35, the unit area being 1 μm×1 μm, A ratio of an average area of ​​the shell included in the at least one dielectric grain having the core-shell structure to an average area of ​​the at least one dielectric grain having the core-shell structure is 30% to 50%.

13. The multilayer capacitor according to claim 12, wherein The average molar ratio of barium to titanium in the core of the at least one dielectric grain is from 0.9980 to 1.0050.

14. The multilayer capacitor according to claim 12, wherein: A ratio of an average area of ​​the shell included in the at least one dielectric grain having the core-shell structure to an average area of ​​the at least one dielectric grain having the core-shell structure is 38% to 46%.

15. The multilayer capacitor according to claim 12, wherein The main component includes at least one selected from the group consisting of BaTiO3, Ba(Ti,Zr)O3, Ba(Ti,Sn)O3, (Ba,Ca)TiO3, (Ba,Ca)(Ti,Zr)O3, (Ba,Ca)(Ti,Sn)O3, (Ba,Sr)TiO3, (Ba,Sr)(Ti,Zr)O3 and (Ba,Sr)(Ti,Sn)O3.

16. The multilayer capacitor according to claim 12, wherein The dielectric grains further include a secondary component, and The subcomponent includes at least one selected from the group consisting of Dy, Mn, V, Si, and Al.

17. The multilayer capacitor according to claim 16, wherein The Dy, Mn, V, Si and Al in the auxiliary components are added in the form of Dy2O3, MnO2, V2O5, SiO2 and Al2O3, respectively. With respect to 100 mol parts of the main component, 0.5 mol to 1.5 mol parts of Dy2O3, 0.05 mol to 0.15 mol parts of MnO2, 0.05 mol to 0.15 mol parts of V2O5, 0.5 mol to 1.0 mol parts of SiO2 or 0.2 mol to 1.0 mol parts of Al2O3 are added, and The auxiliary component further includes Ba added in the form of BaCO 3 , and 1.0 to 2.5 parts by mole of BaCO 3 is added relative to 100 parts by mole of the main component.

18. The multilayer capacitor according to claim 16, wherein The shell includes greater than 0.1 mol parts and less than or equal to 30.0 mol parts of the secondary component relative to 100 mol parts of the primary component, and The core includes 0.1 mol parts or less of the subcomponent relative to 100 mol parts of the main component.

19. The multilayer capacitor according to claim 12, wherein: The average diameter of the core is 50 nm to 500 nm.

20. The multilayer capacitor according to claim 12, wherein The dielectric layer has an average thickness of 0.15 μm to 10 μm.

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