Dielectric ceramic composition and multilayer ceramic capacitor including the same

Abstract

Provided is a dielectric ceramic composition and a multilayer ceramic capacitor comprising the same. The dielectric ceramic composition comprises BaTiO 3 A base material main component and a subsidiary component, wherein the subsidiary component includes dysprosium (Dy) and cerium (Ce) as a first subsidiary component. Based on 100 mol of the base material main component, the total content of Dy and Ce is greater than 0.25 mol and less than or equal to 1.0 mol, the first subsidiary component also includes an oxide or carbonate containing La, and based on 100 mol of the base material main component, the dielectric ceramic composition includes an oxide or carbonate of La in an amount greater than or equal to 0.233 mol and less than or equal to 0.699 mol.

Description

[0001] This application is a divisional application of the invention patent application "Dielectric ceramic composition and multilayer ceramic capacitor comprising the same" with an application date of April 7, 2020 and application number 202010264305.9. Technical Field

[0002] The present disclosure relates to a dielectric ceramic composition having improved reliability and a multilayer ceramic capacitor including the same. Background Art

[0003] Generally, electronic components using ceramic materials, such as capacitors, inductors, piezoelectric elements, varistors, thermistors, etc., include a ceramic body formed using the ceramic material, an internal electrode formed in the ceramic body, and an external electrode mounted on a surface of the ceramic body to be connected to the internal electrode.

[0004] Recently, due to the trend that electronic products and chip components are miniaturized and multifunctionalized, multilayer ceramic capacitors having a smaller size but a larger capacity are required.

[0005] A method for miniaturizing a multilayer ceramic capacitor and increasing its capacity at the same time is to reduce the thickness of the dielectric layer and the inner electrode layer to stack a greater number of layers. Currently, the thickness of the dielectric layer is about 0.6 μm, and efforts have been made to develop thinner dielectric layers.

[0006] In this case, ensuring the reliability of the dielectric layer has become a major issue for dielectric materials. In addition, as the degradation of the insulation resistance of the dielectric material increases, difficulties in managing quality and yield have become a problem.

[0007] In order to solve these problems, it is necessary to develop a new method for ensuring high reliability not only for the structure of the multilayer ceramic capacitor but also, in particular, for the composition of the dielectric.

[0008] When a dielectric composition having a high dielectric constant and improved current reliability is ensured, a thinner multilayer ceramic capacitor can be manufactured. Summary of the invention

[0009] An aspect of the present disclosure provides a dielectric ceramic composition having improved reliability and a multilayer ceramic capacitor including the same.

[0010] According to one aspect of the present disclosure, a dielectric ceramic composition includes: a main component and a subsidiary component of a barium titanate (BaTiO3)-based matrix material. The subsidiary component includes dysprosium (Dy) and cerium (Ce) as a first subsidiary component. Based on 100 mol of the main component of the matrix material, the total content of Dy and Ce is greater than 0.25 mol and less than or equal to 1.0 mol.

[0011] According to another aspect of the present disclosure, a multilayer ceramic capacitor includes: a ceramic body including a dielectric layer and a first inner electrode and a second inner electrode arranged to face each other, and the respective dielectric layer is interposed between the first inner electrode and the second inner electrode; and a first outer electrode and a second outer electrode arranged on the outer surface of the ceramic body. The first outer electrode is electrically connected to the first inner electrode, and the second outer electrode is electrically connected to the second inner electrode, and the dielectric layer includes dielectric grains containing a dielectric ceramic composition. The dielectric ceramic composition includes a BaTiO3-based matrix material main component and a subcomponent, wherein the subcomponent includes Dy and Ce as a first subcomponent. Based on 100 mol of the main component of the matrix material, the total content of Dy and Ce is greater than 0.25 mol and less than or equal to 1.0 mol. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other aspects, features and advantages of the present disclosure will be more clearly understood through the following detailed description in conjunction with the accompanying drawings, in which:

[0013] Figure 1 is a schematic perspective view of a multilayer ceramic capacitor according to an embodiment;

[0014] Figure 2 is along Figure 1 A cross-sectional view taken along line II' in FIG.

[0015] Figure 3 is a graph showing results of dielectric constant with respect to temperature according to embodiment examples and comparative examples. DETAILED DESCRIPTION

[0016] Hereinafter, embodiments of the present disclosure will be described as follows with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Specifically, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. In the accompanying drawings, for the sake of clarity, the shapes and sizes of the elements may be exaggerated, and the same reference numerals will always be used to represent the same or similar elements.

[0017] Figure 1 is a schematic perspective view of a multilayer ceramic capacitor according to an embodiment.

[0018] Figure 2 is along Figure 1 A cross-sectional view taken along line II' in FIG.

[0019] Reference Figure 1 and Figure 2The multilayer ceramic capacitor 100 according to the embodiment includes: a ceramic body 110 including a dielectric layer 111 and first and second internal electrodes 121 and 122 disposed to face each other with respective dielectric layers interposed therebetween; and first and second external electrodes 131 and 132 disposed on outer surfaces of the ceramic body 110. The first external electrode 131 is electrically connected to the first internal electrode 121, and the second external electrode 132 is electrically connected to the second internal electrode 122.

[0020] Regarding the multilayer ceramic capacitor 100 according to the embodiment, Figure 1 The “length direction”, “width direction” and “thickness direction” of the dielectric layer are defined as the “L” direction, the “W” direction and the “T” direction, respectively. The “thickness direction” may be used in the same meaning as the direction in which dielectric layers are stacked (eg, the “stacking direction”).

[0021] Although not particularly limited, the configuration of the ceramic body 110 may be a rectangular cuboid shape as shown in the drawings.

[0022] The plurality of first internal electrodes 121 and the plurality of second internal electrodes 122 formed inside the ceramic body 110 have one end exposed to one surface of the ceramic body 110 or another surface of the ceramic body 110 disposed opposite to the one surface.

[0023] The internal electrode may include a pair of first and second internal electrodes 121 and 122 having different polarities.

[0024] One end of the first internal electrode 121 may be exposed to one surface of the ceramic body, and one end of the second internal electrode 122 may be exposed to the other surface of the ceramic body disposed opposite to the one surface.

[0025] The first and second external electrodes 131 and 132 are respectively formed on one surface and another surface of the ceramic body 110 disposed opposite to the one surface, and may be electrically connected to the internal electrodes.

[0026] The material of the first and second internal electrodes 121 and 122 is not particularly limited and may be a conductive paste including at least one element selected from the group consisting of, for example, silver (Ag), lead (Pb), platinum (Pt), nickel (Ni), and copper (Cu).

[0027] The first and second external electrodes 131 and 132 may be electrically connected to the first and second internal electrodes 121 and 122 , respectively, to generate capacitance. The second external electrode 132 may be connected to a potential different from that connected to the first external electrode 131 .

[0028] The conductive material included in the first and second external electrodes 131 and 132 is not particularly limited, but may include at least one element selected from the group consisting of nickel (Ni), copper (Cu), and alloys thereof.

[0029] The thickness of the first and second external electrodes 131 and 132 may be appropriately determined according to their uses, etc., and is not particularly limited, but may be, for example, 10 μm to 50 μm.

[0030] According to an embodiment, the material forming the dielectric layer 111 is not particularly limited as long as sufficient capacitance can be obtained therewith, and is not particularly limited, and may be, for example, BaTiO 3 powder.

[0031] The material forming the dielectric layer 111 may include various additives added to BaTiO 3 powder or the like, an organic solvent, a plasticizer, a binder, a dispersant, and the like.

[0032] The dielectric layers 111 in a sintered state may be integrated into a single body such that boundaries between adjacent dielectric layers 111 may not be apparent.

[0033] The first and second internal electrodes 121 and 122 may be formed on the dielectric layer 111 , and the internal electrodes 121 and 122 may be formed inside the ceramic body 110 by sintering while having a dielectric layer therebetween.

[0034] The thickness of the dielectric layer 111 may be optionally varied according to the capacitance design of the capacitor. The thickness of the dielectric layer in the sintered embodiment may be 0.4 μm or less per layer.

[0035] In addition, after sintering, the thickness of the first and second internal electrodes 121 and 122 may be 0.4 μm or less per layer.

[0036] According to an embodiment, the dielectric layer 111 includes dielectric particles including a dielectric ceramic composition. The dielectric ceramic composition includes a BaTiO3-based matrix material main component and a subcomponent, wherein the subcomponent includes dysprosium (Dy) and cerium (Ce) as a first subcomponent. Based on 100 mol of the matrix material main component, the total content of Dy and Ce is greater than 0.25 mol and less than or equal to 1.0 mol.

[0037] In order to develop a miniaturized multilayer ceramic capacitor with high capacity, it has recently been required to develop a composition of a dielectric composition that allows a high dielectric constant by enhancing domain wall mobility when similar-sized grains are formed in a main component of a BaTiO 3 -based matrix material containing an additive.

[0038] In this regard, it was shown that when donor-type dopant compositions are applied, the pinning source concentration in the lattice is reduced, leading to high domain wall mobility.

[0039] By applying an additive whose ion size is most similar to that of barium (Ba) among various known donor-type dopants, a dielectric composition capable of minimizing lattice mismatch and allowing a high dielectric constant is developed.

[0040] In addition, since generally when the content of the donor-type additive increases, the insulation resistance (IR) decreases and it is not easy to ensure the reduction resistance, an appropriate content ratio should be determined.

[0041] Generally, dysprosium (Dy) is the most commonly used donor-type dopant, which affects the improvement of dielectric constant and reliability of multilayer ceramic capacitors. By properly adjusting the content of such donor-type dopant and acceptor-type dopant, the desired dielectric characteristics and reliability can be achieved.

[0042] Although Dy is substituted at the A site of BaTiO3 to suppress oxygen vacancies, the realization of this property is limited due to the solid solution limitation of elemental barium (Ba).

[0043] Therefore, it is necessary to make the rare earth elements replace in the element Ba more smoothly so as to maximize the solid solution effect.

[0044] Specifically, in order to increase the donor effect, it is necessary to use a rare earth element having a valence greater than that of Dy (the ion size of Dy is similar to that of Ba) and an ion size greater than that of Dy.

[0045] In the present disclosure, a dielectric composition including cerium (Ce) (a rare earth element having a valence of 4 or more) capable of defect-chemically suppressing the generation of oxygen vacancies in a dielectric composition or reducing the concentration of oxygen vacancies is invented.

[0046] Since Ce has an ionic radius larger than that of elemental barium (Ba) (as a main component of the dielectric composition) and elemental Dy (as a donor-type dopant having an ionic radius similar to that of elemental Ba), Ce can effectively substitute at the Ba site.

[0047] In addition, the element Ce has a high valence state and thus can effectively remove oxygen vacancies serving as donors.

[0048] In the embodiment, a high dielectric constant and excellent reliability are ensured by applying Ce showing stable dielectric characteristics in addition to Dy and determining an optimal content ratio.

[0049] According to an embodiment, the dielectric ceramic composition includes a BaTiO3-based matrix material main component and a subsidiary component, wherein the subsidiary component includes Dy and Ce as a first subsidiary component. Based on 100 mol of the matrix material main component, the total content of Dy and Ce is greater than 0.25 mol and less than or equal to 1.0 mol.

[0050] By adjusting the total content of Dy and Ce to more than 0.25 mol and less than or equal to 1.0 mol based on 100 mol of the main component of the base material, a high dielectric constant can be obtained and reliability such as insulation resistance can be improved.

[0051] According to an embodiment, a dielectric ceramic composition included in a dielectric layer in a ceramic body includes Dy and Ce (rare earth elements) as subcomponents. By adjusting the Dy and Ce contents, high dielectric characteristics can be obtained and reliability such as insulation resistance can be improved.

[0052] When the total content of Dy and Ce is less than or equal to 0.25 mol based on 100 mol of the main component of the base material, the content of the rare earth element may be insufficient, thereby causing a decrease in reliability under a high temperature and high pressure environment.

[0053] In other words, when the total content of Dy and Ce is less than or equal to 0.25 mol based on 100 mol of the main component of the base material, the rare earth element is substituted at the A site and the suppression of oxygen vacancies becomes insufficient. This will deteriorate the reliability, resulting in insufficient improvement in the dielectric constant.

[0054] In addition, when the total content of Dy and Ce is greater than 1.0 mol based on 100 mol of the main component of the base material, the content of the rare earth element serving as a donor increases, and thus the electron concentration also increases. This may cause a decrease in insulation resistance due to semiconductorization.

[0055] According to an embodiment, the Ce content in the dielectric ceramic composition may satisfy 0.233 mol≦Ce≦0.932 mol based on 100 mol of the main component of the base material.

[0056] By adjusting the Ce content to satisfy 0.233 mol≦Ce≦0.932 mol based on 100 mol of the main component of the base material, high dielectric characteristics can be obtained and reliability such as insulation resistance can be improved.

[0057] Specifically, by adjusting the Ce content to satisfy 0.466 mol≦Ce≦0.932 mol based on 100 mol of the main component of the base material, high dielectric characteristics can be obtained and reliability such as insulation resistance can be improved.

[0058] When the Ce content is less than 0.233 mol based on 100 mol of the main component of the base material, the dielectric constant is not significantly increased compared with a conventional dielectric ceramic composition containing only Dy.

[0059] However, as in the embodiment of the present disclosure, when the Ce content is greater than or equal to 0.233 mol based on 100 mol of the main component of the matrix material, oxygen vacancies can be removed more effectively than in a conventional dielectric ceramic composition containing only Dy. Therefore, domain wall mobility is improved, and thus a high dielectric constant can be achieved.

[0060] However, when the Ce content is greater than 0.932 mol based on 100 mol of the main component of the base material, the content of the rare earth element serving as a donor increases, and thus the electron concentration also increases, which may lead to a decrease in insulation resistance due to semiconductorization.

[0061] According to an embodiment, the first subcomponent further includes an oxide or a carbonate including lanthanum (La), and lanthanum (La) may be disposed at boundaries of dielectric grains.

[0062] Furthermore, when a rare earth element having an ion radius larger than that of Dy, such as La, is used, Ba sites can be more effectively substituted, thereby making it more effective for reducing the oxygen vacancy concentration.

[0063] Therefore, La may be further included as the first subcomponent to ensure insulation resistance while minimizing the oxygen vacancy concentration to improve reliability.

[0064] However, if the La content is too high, the insulation resistance may decrease rapidly due to excessive semiconductorization. Therefore, it is preferred that the La content is greater than or equal to 0.233 mol and less than or equal to 0.699 mol based on 100 mol of the main component of the base material.

[0065] As described above, the multilayer ceramic capacitor 100 according to the embodiment is a miniaturized product with high capacity and includes the dielectric layer 111 having a thickness of 0.4 μm or less and the first and second internal electrodes 121 and 122 having a thickness of 0.4 μm or less, but the thickness is not limited thereto.

[0066] In addition, the size of the multilayer ceramic capacitor 100 may be 1005 (length×width, 1.0 mm×0.5 mm) or less.

[0067] In other words, since the multilayer ceramic capacitor 100 according to the embodiment is a miniaturized product with high capacity, the thickness of the dielectric layer 111 and the first and second internal electrodes 121 and 122 are thinner than those of the prior art product. For such a product to which a thin film dielectric layer and internal electrodes are applied, it is very important to study the improvement of reliability such as insulation resistance.

[0068] In other words, since the related art multilayer ceramic capacitor has relatively thicker dielectric layers and inner electrodes than the multilayer ceramic capacitor according to the embodiment of the present disclosure, reliability is not a big problem even if the composition of the dielectric ceramic composition is the same as that of the related art.

[0069] However, for a product of a multilayer ceramic capacitor to which a thin film dielectric layer and an inner electrode are applied as an embodiment of the present disclosure, reliability of the multilayer ceramic capacitor is important, and the composition of the dielectric ceramic composition needs to be adjusted.

[0070] That is, in the embodiment, even in the case where the dielectric layer 111 is a thin film with a thickness of 0.4 μm or less, reliability such as insulation resistance can be improved by including the first subcomponent Dy and Ce in an amount greater than 0.25 mol and less than or equal to 1.0 mol based on 100 mol of the main component of the base material. By adjusting the Ce content to satisfy 0.233 mol ≤ Ce ≤ 0.932 mol based on 100 mol of the main component of the base material, reliability such as insulation resistance can be improved even when the dielectric layer 111 is a thin film with a thickness of 0.4 μm or less.

[0071] However, thin film does not mean that the thickness of the dielectric layer 111 and the internal electrodes 121 and 122 is 0.4 μm or less, and may be understood to mean that the dielectric layer and the internal electrodes are thinner than those of related art products.

[0072] Hereinafter, each component of the dielectric ceramic composition according to an embodiment will be described in more detail.

[0073] (a) Main components of matrix materials

[0074] The dielectric ceramic composition according to an embodiment of the present disclosure may include a matrix material main component represented by BaTiO 3 .

[0075] According to the embodiment, the main component of the matrix material includes BaTiO3, (Ba 1-x Ca x )(Ti 1-y Ca y )O3(where 0≤x≤0.3, 0≤y≤0.1),(Ba 1-x Ca x)(Ti 1-y Zr y )O3 (where 0 ≤ x ≤ 0.3, 0 ≤ y ≤ 0.5) and at least one selected from the group consisting of Ba(Ti 1-y Zr y )O3 (where 0 < y ≤ 0.5), but not limited thereto.

[0076] The dielectric ceramic composition according to the embodiment may have a room-temperature dielectric constant of 2000 or higher.

[0077] The main component of the base material is not particularly limited, but the average diameter of the main component powder may be greater than or equal to 40 nm and less than or equal to 150 nm.

[0078] (b) First sub-component

[0079] According to an embodiment of the present disclosure, the dielectric ceramic composition substantially includes Dy and Ce as elements of the first sub-component, and based on 100 mol of the main component of the base material, the dielectric ceramic composition may further include an oxide or carbonate of lanthanum (La) in an amount greater than or equal to 0.233 mol and less than or equal to 0.699 mol.

[0080] In the embodiment, the first sub-component is used to suppress the reliability degradation of the multilayer ceramic capacitor to which the dielectric ceramic composition is applied.

[0081] When the La content is less than 0.233 mol, the dielectric constant does not increase. When the La content exceeds 0.699 mol, the insulation resistance or loss factor (DF) may decrease.

[0082] According to the embodiment, by including Dy and Ce as the first sub-component in an amount greater than 0.25 mol and less than or equal to 1.0 mol (based on 100 mol of the main component of the base material) and adjusting the Ce content present in the dielectric ceramic composition to satisfy 0.233 mol ≤ Ce ≤ 0.932 mol (specifically, 0.466 mol ≤ Ce ≤ 0.932 mol) (based on 100 mol of the main component of the base material), even when the thickness of the dielectric layer 111 is 0.4 μm or less, the reliability such as insulation resistance can be improved.

[0083] When the Ce content is less than 0.233 mol based on 100 mol of the main component of the base material, the dielectric constant does not increase significantly compared to the conventional dielectric ceramic composition containing only Dy.

[0084] When the Ce content is greater than 0.932 mol based on 100 mol of the main component of the base material, the insulation resistance may decrease due to semi-conduction.

[0085] (c) Second sub-component

[0086] According to an embodiment of the present disclosure, the dielectric ceramic composition may include an oxide including at least one element selected from the group consisting of manganese (Mn), vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), and zinc (Zn) or a carbonate including at least one element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn as a second subcomponent.

[0087] An oxide containing at least one element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu and Zn and a carbonate containing at least one element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu and Zn may be included as a second subcomponent in an amount of 0.1 mol to 2.0 mol based on 100 mol of the main component of the base material.

[0088] The second subcomponent is used to lower the firing temperature and enhance the high temperature withstand voltage characteristics of the multilayer ceramic capacitor to which the dielectric ceramic composition is applied.

[0089] The contents of the second subcomponent and third and fourth subcomponents to be described may be amounts included in the dielectric ceramic composition based on 100 mol of the base material main component, and specifically, may be defined as the number of moles of metal ions included in each subcomponent.

[0090] When the content of the second subcomponent is less than 0.1 mol, the firing temperature increases and the high-temperature withstand voltage characteristics may slightly decrease.

[0091] When the content of the second subcomponent is greater than 2.0 mol, high temperature withstand voltage characteristics and room temperature specific resistance may be reduced.

[0092] Specifically, the dielectric ceramic composition according to an embodiment of the present disclosure may include 0.1 mol to 2.0 mol of the second subcomponent based on 100 mol of the main component of the base material. This will enable firing at low temperature and provide high temperature withstand voltage characteristics.

[0093] (d) The third subcomponent

[0094] According to an embodiment of the present disclosure, the dielectric ceramic composition may include a third subcomponent which is an oxide or a carbonate of a fixed-valence acceptor element including magnesium (Mg).

[0095] The fixed valence acceptor element Mg may be included as the third subcomponent in an amount of 0.001 mol to 0.5 mol based on 100 mol of the main component of the base material.

[0096] The third subcomponent as a fixed valence acceptor element or a compound including a fixed valence acceptor element is used as an acceptor to reduce electron concentration. By adding 0.001 mol to 0.5 mol of the fixed valence acceptor element Mg as the third subcomponent based on 100 mol of the main component of the base material, the reliability improvement effect due to the n-type can be significantly improved.

[0097] When the content of the third subcomponent is greater than 0.5 mol based on 100 mol of the main component of the base material, the dielectric constant may decrease, which may be problematic.

[0098] However, according to an embodiment, it is preferred to include 0.5 mol of the third subcomponent based on 100 mol of Ti to maximize the reliability improvement caused by the n-type, but is not limited thereto. The third subcomponent may be included in an amount of 0.5 mol or less or slightly more than 0.5 mol.

[0099] (e) Fourth subcomponent

[0100] According to an embodiment of the present disclosure, the dielectric ceramic composition may include an oxide including at least one element of silicon (Si) and aluminum (Al) or a glass compound including Si as a fourth subcomponent.

[0101] The dielectric ceramic composition may further include 0.001 mol to 4.0 mol of a fourth subcomponent including an oxide including at least one element of Si and Al or a glass compound including Si, based on 100 mol of the main component of the base material.

[0102] The content of the fourth subcomponent may be the content of at least one element of Si and Al contained in the fourth subcomponent regardless of the addition form such as glass, oxide.

[0103] The fourth subcomponent is used to lower the firing temperature and improve the high temperature withstand voltage characteristics of the multilayer ceramic capacitor to which the dielectric ceramic composition is applied.

[0104] When the content of the fourth subcomponent exceeds 4.0 mol based on 100 mol of the main component of the base material, there may be problems such as reduction in sinterability and density, formation of a second phase, etc., which may be problematic.

[0105] In particular, according to the embodiment, when the dielectric ceramic composition includes 4.0 mol or less of Al, grain growth may be controlled to be uniform, thereby improving withstand voltage characteristics and reliability as well as DC bias characteristics.

[0106] Hereinafter, the present disclosure will be described in more detail with reference to embodiments and comparative examples of the present disclosure. These embodiments and comparative examples are provided to help a comprehensive understanding of the present invention and should not be construed as being limited to the embodiments set forth herein.

[0107] (Example of Embodiment)

[0108] The dielectric layer is formed by the following process: additives (such as Dy, Ce, La, Al, Mg, Mn, etc.), binders and organic solvents (such as ethanol) are added to dielectric powder containing BaTiO3 and wet-mixed to prepare dielectric slurry, and then the dielectric slurry is spread on a carrier film and dried to prepare a ceramic green sheet.

[0109] All element additives having a particle size of 40 or less of BaTiO3 are monodispersed and added.

[0110] Specifically, among the rare earth elements added to the dielectric slurry, Dy and Ce are added in an amount greater than 0.25 mol and less than or equal to 1.0 mol based on 100 mol of the main component of the base material.

[0111] In Embodiment Example 1, 0.466 mol of Dy and 0.466 mol of Ce were added to the dielectric slurry, and in Embodiment Example 2, 0.233 mol of Dy and 0.699 mol of Ce were added to the dielectric slurry.

[0112] The dielectric slurry was prepared into a ceramic green sheet having a thickness of several micrometers by using a doctor blade method.

[0113] Then, a conductive paste for an internal electrode including 40 to 50 parts by weight (relative to 100 parts by weight of the conductive paste) of nickel powder having an average particle diameter of 0.1 to 0.2 μm was prepared.

[0114] Conductive paste for internal electrodes is screen-printed on ceramic green sheets to form internal electrode patterns. The green sheets on which the internal electrode patterns are formed are then laminated to form a laminate, which is then pressed and cut.

[0115] Then, the cut laminated body is heated to remove the binder, and fired in a high-temperature reducing atmosphere to form a ceramic body.

[0116] During the firing process, heat treatment was performed by firing at 1100° C. to 1200° C. in a reducing atmosphere (0.1% H 2 / 99.9% N 2 , H 2 O / H 2 / N 2 ) for 2 hours and then oxidizing at 1000° C. in a nitrogen (N 2 ) atmosphere for 3 hours.

[0117] A termination process and electrode firing are performed on the fired ceramic body using a copper (Cu) paste, and external electrodes are formed.

[0118] In addition, the dielectric layer 111 and the first and second internal electrodes 121 and 122 inside the ceramic body 110 are manufactured to have a thickness of 0.4 μm or less after firing.

[0119] (Comparative Example 1)

[0120] Comparative Example 1 represents a conventional case where 0.932 mol of Dy is added based on 100 mol of the main component of the base material. The remaining manufacturing process is the same as the manufacturing process described in the embodiment example.

[0121] (Comparative Example 2)

[0122] In Comparative Example 2, 0.699 mol of Dy and 0.233 mol of Ce were added based on 100 mol of the main component of the base material. The remaining manufacturing process was the same as that described in the embodiment example.

[0123] (Comparative Example 3)

[0124] In Comparative Example 3, 0.932 mol of Ce was added based on 100 mol of the main component of the base material. The remaining manufacturing process was the same as that described in the embodiment example.

[0125] Embodiment Examples 1 and 2 and Comparative Examples 1 to 3 (prototype multilayer ceramic capacitor (MLCC) samples manufactured as above) were tested for dielectric constant, dissipation factor (DF), and insulation resistance (IR), and the results thereof were evaluated.

[0126] In the following two states (ie, the ceramic state and the multilayer ceramic capacitor state), tests were performed to accurately measure the effect of Ce addition.

[0127] Table 1 below shows dielectric constants, DF, and IR of ceramic sheets and prototype MLCCs according to experimental examples (Embodiment Examples 1 and 2 and Comparative Examples 1 to 3).

[0128] [Table 1]

[0129]

[0130] Referring to Table 1, Comparative Example 1, in which only 0.932 mol of Dy was added to the dielectric ceramic composition based on 100 mol of the main component of the base material, showed low dielectric constant and insulation resistance.

[0131] Comparative Example 2, in which the Ce content was 0.233 mol based on 100 mol of the main component of the base material, showed a significantly improved dielectric constant compared to Comparative Example 1 using only Dy.

[0132] Comparative Example 3 in which only 0.932 mol of Ce was added based on 100 mol of the main component of the base material showed a tendency to suffer from semiconductorization and reduced IR and had a problem with DF.

[0133] In contrast, the Dy and Ce contents of Example Examples 1 and 2 are greater than 0.25 mol and less than or equal to 1.0 mol based on 100 mol of the main component of the base material, which satisfies 0.233 mol ≤ Ce ≤ 0.932 mol, specifically, 0.466 mol ≤ Ce ≤ 0.932 mol based on 100 mol of the main component of the base material. This results in a high dielectric constant and improved reliability (such as insulation resistance, etc.).

[0134] Figure 3 is a graph showing results of dielectric constant with respect to temperature according to the embodiment example and the comparative example.

[0135] Reference Figure 3 , compared with Comparative Example 1 using only Dy, Example Examples 1 and 2 show significantly improved dielectric constants with respect to temperature, wherein, in Example Examples 1 and 2, based on 100 mol of the main component of the matrix material, the Dy and Ce contents are greater than 0.25 mol and less than or equal to 1.0 mol, and based on 100 mol of the main component of the matrix material, the Ce content satisfies 0.233 mol≤Ce≤0.932 mol, specifically, 0.466 mol≤Ce≤0.932 mol.

[0136] Furthermore, Comparative Example 3 in which only 0.932 mol of Ce was included based on 100 mol of the main component of the base material showed a high dielectric constant; however, there was a tendency toward semiconductorization, which may result in a decrease in insulation resistance, thereby causing a reliability problem.

[0137] According to embodiments, a dielectric ceramic composition may have improved reliability, such as improved insulation resistance, by including a new rare earth element Ce as a subcomponent while controlling the content thereof.

[0138] While embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations may be made without departing from the scope of the present disclosure as defined by the appended claims.

Claims

1. A dielectric ceramic composition comprising: BaTiO3-based matrix material main components and auxiliary components, wherein the auxiliary components include Dy and Ce as first auxiliary components; and Based on 100 mol of the main component of the matrix material, the total content of Dy and Ce is greater than 0.25 mol and less than or equal to 1.0 mol, The first subcomponent further includes an oxide or carbonate containing La, and the dielectric ceramic composition includes the oxide or carbonate of La in an amount greater than or equal to 0.233 mol and less than or equal to 0.699 mol based on 100 mol of the base material main component.

2. The dielectric ceramic composition according to claim 1, wherein The content of Ce satisfies 0.233 mol≤Ce≤0.932 mol based on 100 mol of the main component of the base material.

3. The dielectric ceramic composition according to claim 1, wherein The dielectric ceramic composition includes 0.1 mol to 2.0 mol of the second subcomponent based on 100 mol of the main component of the base material, The second subcomponent includes an oxide containing at least one element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu and Zn, or a carbonate containing at least one element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu and Zn.

4. The dielectric ceramic composition according to claim 1, further comprising 0.001 mol to 0.5 mol of a third subcomponent based on 100 mol of the main component of the matrix material, in, The third subcomponent is an oxide or a carbonate including a fixed-valence acceptor element Mg.

5. The dielectric ceramic composition according to claim 1, wherein The dielectric ceramic composition includes 0.001 mol to 4.0 mol of the fourth subcomponent based on 100 mol of the main component of the base material, The fourth subcomponent includes an oxide containing at least one element of Si and Al or a glass compound containing Si.

6. The dielectric ceramic composition according to claim 1, wherein The content of Ce satisfies 0.466 mol≤Ce≤0.932 mol based on 100 mol of the main component of the base material.

7. A multilayer ceramic capacitor comprising: a ceramic body including a dielectric layer and first and second internal electrodes disposed to face each other with the respective dielectric layers interposed therebetween; and a first external electrode and a second external electrode disposed on an outer surface of the ceramic body, the first external electrode being electrically connected to the first internal electrode, and the second external electrode being electrically connected to the second internal electrode, wherein the dielectric layer comprises dielectric grains comprising a dielectric ceramic composition, The dielectric ceramic composition comprises a BaTiO3-based matrix material as a main component and a subsidiary component, and The subcomponents include Dy and Ce as first subcomponents, and Based on 100 mol of the main component of the matrix material, the total content of Dy and Ce is greater than 0.25 mol and less than or equal to 1.0 mol, The first subcomponent further includes an oxide or carbonate containing La, and the dielectric ceramic composition includes the oxide or carbonate of La in an amount greater than or equal to 0.233 mol and less than or equal to 0.699 mol based on 100 mol of the base material main component.

8. The multilayer ceramic capacitor according to claim 7, wherein: The content of Ce satisfies 0.233 mol≤Ce≤0.932 mol based on 100 mol of the main component of the base material.

9. The multilayer ceramic capacitor according to claim 7, wherein: La is disposed at the boundaries of the dielectric grains.

10. The multilayer ceramic capacitor according to claim 7, wherein: The dielectric ceramic composition includes 0.1 mol to 2.0 mol of the second subcomponent based on 100 mol of the main component of the base material, The second subcomponent includes an oxide containing at least one element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu and Zn, or a carbonate containing at least one element selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu and Zn.

11. The multilayer ceramic capacitor according to claim 7, wherein: The dielectric ceramic composition includes 0.001 mol to 0.5 mol of the third subcomponent based on 100 mol of the main component of the base material, The third subcomponent includes an oxide or a carbonate containing a fixed-valence acceptor element Mg.

12. The multilayer ceramic capacitor according to claim 7, wherein: The dielectric ceramic composition includes 0.001 mol to 4.0 mol of the fourth subcomponent based on 100 mol of the main component of the base material, The fourth subcomponent includes an oxide containing at least one element of Si and Al or a glass compound containing Si.

13. The multilayer ceramic capacitor according to claim 7, wherein: At least one of the dielectric layers has a thickness of 0.4 μm or less.

14. The multilayer ceramic capacitor according to claim 7, wherein: The multilayer ceramic capacitor has a size of 1005 or less.

15. The multilayer ceramic capacitor according to claim 7, wherein: The content of Ce satisfies 0.466 mol≤Ce≤0.932 mol based on 100 mol of the main component of the base material.

16. The multilayer ceramic capacitor according to claim 7, wherein: A thickness of at least one of the first internal electrode and the second internal electrode is 0.4 μm or less.

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