Dielectric ceramic composition and multilayer ceramic capacitor comprising the same

Abstract

The present disclosure provides a dielectric ceramic composition including a barium titanate (BaTiO3)-based base material main component and a subcomponent, and the subcomponent includes a trivalent lanthanoid rare earth element A and terbium (Tb) as a rare earth element, and a molar ratio (Tb / A) of a content of the terbium (Tb) to a content of the trivalent lanthanoid rare earth element A satisfies 0.15 ≤ Tb / A < 0.50.

Description

[0001] This application is a divisional application of the invention patent application "Dielectric ceramic composition and multilayer ceramic capacitor including the thereof" filed on October 21, 2019, with application number 201910999590.6. Technical Field

[0002] This disclosure relates to a dielectric ceramic composition capable of improving reliability and a multilayer ceramic capacitor comprising the dielectric ceramic composition. Background Technology

[0003] Typically, electronic components using ceramic materials, such as capacitors, inductors, piezoelectric devices, rheostats, and thermistors, may include a ceramic body formed from ceramic materials, an internal electrode disposed in the ceramic body, and an external electrode disposed on the surface of the ceramic body and connected to the internal electrode.

[0004] Recently, while electronic products have been designed to have smaller sizes and multiple functions, the size of chip components has also decreased, and various functions have been implemented within them. Therefore, there is a need for multilayer ceramic capacitors with smaller size and high capacitance.

[0005] To achieve both reduced size and high capacitance in multilayer ceramic capacitors, the thickness of the internal dielectric and electrode layers may need to be reduced, allowing for the stacking of an increased number of internal dielectric and electrode layers. Typically, the dielectric layer thickness is approximately 0.6 μm, and techniques for further reducing the dielectric layer thickness are continuously being developed.

[0006] In this context, ensuring the reliability of the dielectric layer is a major concern for dielectric materials. Furthermore, the increasing defects caused by the degradation of the dielectric material's insulation resistance present challenges in managing product quality and yield.

[0007] To address the aforementioned issues, it has become necessary to ensure high reliability related to both the structural aspects and the composition of the dielectric materials in multilayer ceramic capacitors.

[0008] If a dielectric composition is ensured that can further improve reliability at current levels, the size of multilayer ceramic capacitors can be further reduced than before. Summary of the Invention

[0009] One aspect of this disclosure is to provide a dielectric ceramic composition that improves reliability and a multilayer ceramic capacitor comprising the dielectric ceramic composition.

[0010] According to one aspect of this disclosure, a dielectric ceramic composition comprises a barium titanate (BaTiO3)-based matrix material as a main component and secondary components. The secondary components include trivalent lanthanide rare earth elements A and terbium (Tb) as rare earth elements, and the molar ratio (Tb / A) of the content of terbium (Tb) to the content of the trivalent lanthanide rare earth element A satisfies 0.15 ≤ Tb / A < 0.50.

[0011] According to one aspect of this disclosure, a multilayer ceramic capacitor includes: a ceramic body including a dielectric layer and a first inner electrode and a second inner electrode, the first inner electrode and the second inner electrode being positioned opposite each other and the dielectric layer being disposed therebetween; and a first outer electrode and a second outer electrode, the first outer electrode being electrically connected to the first inner electrode and the second outer electrode being electrically connected to the second inner electrode, the first outer electrode and the second outer electrode being disposed on an outer surface of the ceramic body. The dielectric layer comprises a dielectric ceramic composition comprising a barium titanate (BaTiO3)-based matrix material as a main component and a secondary component, and the secondary component comprises a trivalent lanthanide rare earth element A and terbium (Tb) as rare earth elements, and the molar ratio (Tb / A) of the content of terbium (Tb) to the content of the trivalent lanthanide rare earth element A satisfies 0.15 ≤ Tb / A < 0.50. Attached Figure Description

[0012] The above and other aspects, features and advantages of this disclosure will become clearer from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0013] Figure 1 This is a schematic perspective view showing a multilayer ceramic capacitor according to an exemplary embodiment of the present disclosure;

[0014] Figure 2 It is along Figure 1 A cross-sectional view taken from line II′; and

[0015] Figure 3 This is a graph showing the results of high-acceleration life tests according to embodiments and comparative examples of this disclosure. Detailed Implementation

[0016] In the following description, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure may be implemented in many different forms and should not be construed as limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Therefore, for clarity of description, the shape and size of elements in the drawings may be exaggerated, and elements indicated by the same reference numerals in the drawings are the same elements.

[0017] Figure 1This is a schematic perspective view illustrating a multilayer ceramic capacitor according to an exemplary embodiment of the present disclosure.

[0018] Figure 2 It is along Figure 1 A cross-sectional view taken from line II′.

[0019] Reference Figures 1 to 2 According to an embodiment of the present disclosure, a multilayer ceramic capacitor 100 may include: a ceramic body 110, including a dielectric layer 111 and a first inner electrode 121 and a second inner electrode 122, wherein the first inner electrode 121 and the second inner electrode 122 are arranged opposite to each other and the dielectric layer 111 is disposed therebetween; a first outer electrode 131 electrically connected to the first inner electrode 121; and a second outer electrode 132 electrically connected to the second inner electrode 122 (the first outer electrode 131 and the second outer electrode 132 are disposed on the outer surface of the ceramic body 110).

[0020] In the multilayer ceramic capacitor 100 of the embodiments of this disclosure, such as Figure 1 As shown, "length direction" is the L direction, "width direction" is the W direction, and "thickness direction" is the T direction. Here, the thickness direction can be the same as the stacking direction along which the dielectric layers are stacked.

[0021] The shape of the ceramic body 110 is not limited to any particular shape. For example, as shown in the figure, the ceramic body 110 may have a rectangular parallelepiped shape.

[0022] The plurality of internal electrodes 121 and 122 formed in the ceramic body 110 can be configured such that one end of the plurality of internal electrodes 121 and 122 can be exposed to one surface of the ceramic body 110 or to another surface of the ceramic body 110 opposite to said one surface.

[0023] Regarding the inner electrodes 121 and 122, a pair of first inner electrodes 121 and second inner electrodes 122 with different polarities can be constructed.

[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 another surface of the ceramic body opposite to the first surface.

[0025] The first external electrode 131 and the second external electrode 132 can be formed on one surface of the ceramic body 110 and the other surface of the ceramic body 110 opposite to the first surface, respectively, and can be electrically connected to the internal electrode.

[0026] The materials forming the first internal electrode 121 and the second internal electrode 122 are not limited to any particular material. For example, the materials for the first internal electrode 121 and the second internal electrode 122 may be formed using a conductive paste comprising one or more elements including silver (Ag), lead (Pb), platinum (Pt), nickel (Ni) and copper (Cu).

[0027] The first external electrode 131 and the second external electrode 132 can be electrically connected to the first internal electrode 121 and the second internal electrode 122 respectively to form a capacitor, and the second external electrode 132 can be connected to a potential different from that of the first external electrode 131.

[0028] The conductive materials included in the first external electrode 131 and the second external electrode 132 are not limited to any particular material. For example, nickel (Ni), copper (Cu), or alloys thereof can be used as conductive materials.

[0029] The thicknesses of the first external electrode 131 and the second external electrode 132 can be appropriately determined according to the application, etc., and are not limited to any specific size. For example, the thickness can be in the range of 10 μm to 50 μm.

[0030] According to embodiments of this disclosure, the material of the dielectric layer 111 is not limited to any specific material, as long as sufficient capacitance can be obtained using that material. For example, the material can be barium titanate (BaTiO3) powder.

[0031] Depending on the intended purpose, various additives, organic solvents, plasticizers, coupling agents, dispersants, etc., can be added to barium titanate (BaTiO3) powder as the material for dielectric layer 111.

[0032] The dielectric layer 111 may be in a sintered state, and the dielectric layers 111 may be integrated with each other, making it difficult to identify the boundary between adjacent dielectric layers 111 with the naked eye.

[0033] The first inner electrode 121 and the second inner electrode 122 may be formed on the dielectric layer 111, and the inner electrodes 121 and 122 may be formed in the ceramic body by a sintering process, with a single dielectric layer between the inner electrodes 121 and 122.

[0034] The thickness of dielectric layer 111 can vary depending on the capacitor's capacitance design. In embodiments of this disclosure, the thickness of a single dielectric layer after the sintering process is preferably less than or equal to 0.45 μm.

[0035] Furthermore, the thickness of both the individual first inner electrode 121 and the individual second inner electrode 122 after the sintering process is preferably less than or equal to 0.45 μm.

[0036] According to embodiments of this disclosure, dielectric layer 111 may include a dielectric ceramic composition. The dielectric ceramic composition may include a BaTiO3-based substrate material as a main component and secondary components. The secondary components may include trivalent lanthanide rare earth elements A and terbium (Tb) as rare earth elements, and the molar ratio (Tb / A) of the terbium (Tb) content to the content of trivalent lanthanide rare earth element A satisfies 0.15 ≤ Tb / A < 0.50.

[0037] In particular, the trivalent lanthanide rare earth element A can be dysprosium (Dy).

[0038] According to embodiments of this disclosure, the molar ratio (Tb / A) of terbium (Tb) content to the content of trivalent lanthanide rare earth element A satisfies 0.15 ≤ Tb / A < 0.50. In one embodiment, the molar ratio (Tb / A) of terbium (Tb) content to the content of trivalent lanthanide rare earth element A may be greater than or equal to 0.20, greater than or equal to 0.25, greater than or equal to 0.30, greater than or equal to 0.35, greater than or equal to 0.40, or greater than or equal to 0.45. In another embodiment, the molar ratio (Tb / A) of terbium (Tb) content to the content of trivalent lanthanide rare earth element A may be less than or equal to 0.45, less than or equal to 0.35, less than or equal to 0.30, less than or equal to 0.25, or less than or equal to 0.20.

[0039] When the molar ratio (Tb / A) of terbium (Tb) content to trivalent lanthanide rare earth element A content satisfies 0.15≤Tb / A<0.50, the reliability improvement effect, such as the improvement of insulation resistance, is excellent.

[0040] In particular, the trivalent lanthanide rare earth element A can be dysprosium (Dy), and when the molar ratio of terbium (Tb) content to dysprosium (Dy) content (Tb / Dy) satisfies 0.15≤Tb / Dy<0.50, the reliability improvement effect, such as the improvement of insulation resistance, is excellent.

[0041] According to embodiments of this disclosure, the dielectric ceramic composition in the dielectric layer within the ceramic body contains trivalent lanthanide rare earth element A and terbium (Tb) as secondary components, and reliability, such as improved insulation resistance, can be improved by controlling the molar ratio of terbium (Tb) content to trivalent lanthanide rare earth element A content.

[0042] When the molar ratio (Tb / A) of terbium (Tb) to trivalent lanthanide rare earth element A is less than 0.15, the reliability improvement effect of adding terbium (Tb) may not be significant. Furthermore, when the molar ratio of terbium (Tb) to trivalent lanthanide rare earth element A is 0, that is, when terbium (Tb) is not added (as in the case of the prior art), there may be no reliability improvement effect, which may increase the defect rate.

[0043] When the molar ratio (Tb / A) of terbium (Tb) content to trivalent lanthanide rare earth element A content is greater than or equal to 0.50, the insulation resistance may decrease due to semiconductorization.

[0044] The trivalent lanthanide rare earth element A can be dysprosium (Dy). When the molar ratio of terbium (Tb) to dysprosium (Dy) (Tb / Dy) is less than 0.15, the reliability improvement effect may not be significant. Furthermore, when the molar ratio of terbium (Tb) to dysprosium (Dy) is 0, that is, when terbium (Tb) is not added (as in the case of the prior art), there may be no reliability improvement effect, which may increase the defect rate.

[0045] In addition, when the molar ratio of terbium (Tb) content to dysprosium (Dy) content (Tb / Dy) is greater than or equal to 0.5, the insulation resistance may decrease due to semiconductorization.

[0046] According to embodiments of this disclosure, based on 100 mol% of titanium (Ti) as the main matrix material, the sum of the content of trivalent lanthanide rare earth element A and the content of terbium (Tb) can be greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%. In one embodiment, the sum of the content of trivalent lanthanide rare earth element A and the content of terbium (Tb) can be 0.3 mol%, 0.4 mol%, 0.5 mol%, 0.6 mol%, 0.7 mol%, 0.8 mol%, 0.9 mol%, 1.0 mol%, 1.1 mol%, 1.2 mol%, 1.3 mol%, or 1.4 mol%.

[0047] In particular, the trivalent lanthanide rare earth element A can be dysprosium (Dy).

[0048] Typically, many rare earth elements are added to ensure the reliability of the dielectric within multilayer ceramic capacitors.

[0049] It is well known that rare earth elements such as dysprosium (Dy) can improve reliability by substituting Ba sites in barium titanate (BaTiO3) (the main component of the matrix material) to reduce the concentration of oxygen vacancies.

[0050] Furthermore, when rare earth elements with larger ionic radii than dysprosium (Dy) (such as lanthanum (La) and samarium (Sm)) are used, it is more effective in reducing the concentration of oxygen vacancy defects. However, there is a problem that the insulation resistance decreases sharply due to excessive semiconductorization, so it has not been used in practice.

[0051] Therefore, it is considered best to use rare earth elements with ionic radii larger than those of dysprosium (Dy) but not significantly different in size from dysprosium (Dy) to significantly reduce the concentration of oxygen vacancy defects, thereby improving reliability and also suppressing semiconductorization to ensure insulation resistance.

[0052] Furthermore, since rare earth elements generally have a fixed valence state of +3, when they substitute for Ba (+2), they acquire a single positive charge D. · Ba However, when the oxidation state can have multiple valence states of +4 (such as terbium (Tb)), they have a double positive charge D. ‥ Ba This means that reducing oxygen vacancy defects can have two effects.

[0053] Conversely, in the case of multivalent states with +3 (such as ytterbium (Yb)), when Ba (+2) is substituted, it may not be effective in reducing the concentration of oxygen vacancy defects because it is electrically neutral. Therefore, it is well known that reliability may be further degraded when ytterbium (Yb) is added.

[0054] As a result, although the ionic radius is larger than that of dysprosium (Dy), terbium (Tb), with its multiple valence states but insufficient for semiconductorization to reduce insulation resistance, is most effective in reducing the concentration of oxygen vacancy defects, leading to a significant improvement in the reliability of the dielectric in multilayer ceramic capacitors. Therefore, a dielectric ceramic composition containing both dysprosium (Dy) and terbium (Tb) has been developed.

[0055] In the prior art, attempts have been made to add one or more of the rare earth elements dysprosium (Dy), gadolinium (Gd), and terbium (Tb) to the dielectric ceramic composition.

[0056] Even in this case, terbium (Tb) was only listed as a rare earth element or added in small amounts without recognizing the aforementioned effects of terbium (Tb), and no specific study was conducted on the content of added terbium (Tb) in order to improve reliability.

[0057] In the embodiments of this disclosure, the optimal ratio of added dysprosium (Dy) and terbium (Tb) was sought, and a ratio that yielded excellent results in improving reliability was discovered.

[0058] According to embodiments of this disclosure, by controlling the sum of the content of trivalent lanthanide rare earth element A and the content of terbium (Tb) in titanium (Ti), a main component of the matrix material at 100 mol%, to be greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%, reliability, such as improved insulation resistance, can be improved.

[0059] When the trivalent lanthanide rare earth element A is dysprosium (Dy), the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), the main component of the matrix material, is greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%.

[0060] By controlling the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), a main component of the matrix material, to be greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%, reliability improvements, such as improvements in insulation resistance, can be achieved.

[0061] Increasing the total content of rare earth elements can be advantageous in terms of reliability. However, since the temperature characteristics decrease significantly when the case temperature (Tc) is moved to room temperature, it is preferable to control the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), which is a 100 mol% matrix material, to be less than or equal to 1.5 mol%.

[0062] When the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), which is a 100 mol% matrix material, exceeds 1.5 mol%, temperature characteristics such as the temperature coefficient of capacitance (TCC) may decrease.

[0063] On the other hand, reliability may decrease when the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), which is a main component of the matrix material at 100 mol%, is less than 0.2 mol%.

[0064] As described above, the multilayer ceramic capacitor 100 according to embodiments of the present disclosure is a very small and high-capacitance product. The thickness of the dielectric layer 111 may be less than or equal to 0.45 μm, and the thicknesses of the first inner electrode 121 and the second inner electrode 122 may be less than or equal to 0.45 μm, but are not necessarily limited thereto.

[0065] In other words, since the multilayer ceramic capacitor 100 according to the embodiments of this disclosure is a very small and high-capacitance product, the dielectric layer 111, the first internal electrode 121, and the second internal electrode 122 are formed using films that are thinner than those in products of the prior art. Therefore, in the case of products using thin-film dielectric layers and internal electrodes, research into improving reliability, such as improving insulation resistance, can be an important issue.

[0066] In other words, in the prior art, the thickness of its dielectric layer and internal electrode is relatively thicker than that of the dielectric layer and internal electrode contained in the multilayer ceramic capacitor according to the present disclosure. Therefore, even when the composition of the dielectric ceramic composition is the same as that of the dielectric ceramic composition in the prior art, reliability is not a serious problem.

[0067] However, as in the embodiments of this disclosure, it may be difficult to ensure the reliability of multilayer ceramic capacitors in products that utilize thin-film dielectric layers and internal electrodes. Therefore, controlling the composition of the dielectric ceramic composition is essential.

[0068] That is, in the embodiments of the present disclosure, by controlling the sum of the contents of trivalent lanthanide rare earth element A and terbium (Tb) based on titanium (Ti) as the main component of the matrix material at 100 mol% to be greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%, particularly by controlling the molar ratio (Tb / A) of the content of terbium (Tb) to the content of trivalent lanthanide rare earth element A to satisfy 0.15 ≤ Tb / A < 0.50, even when the dielectric layer 111 and the first internal electrode 121 and the second internal electrode 122 are thin films having a thickness of less than or equal to 0.45 μm, the reliability such as improvement in insulation resistance can be improved.

[0069] However, the meaning of the thin film may not mean that the thicknesses of the dielectric layer 111 and the first internal electrode 121 and the second internal electrode 122 are less than or equal to 0.45 μm, and the meaning of the thin film can be understood to include the concept of a dielectric layer and an internal electrode that are thinner than those of the products in the prior art.

[0070] Hereinafter, each component of the dielectric ceramic composition according to the embodiments of the present disclosure will be described in more detail.

[0071] a) Main component of the matrix material

[0072] The dielectric ceramic composition according to the embodiments of the present disclosure may include a main component of the matrix material represented by BaTiO3.

[0073] According to the embodiments of the present disclosure, the main component of the matrix material may include one or more elements selected from the group consisting of (Ba 1-x Ca x )(Ti 1-y Ca y )O3 (where x may satisfy 0 ≤ x ≤ 0.3 and y may satisfy 0 ≤ y ≤ 0.1), (Ba 1-x Ca x )(Ti 1-y Zr y )O3 (where x may satisfy 0 ≤ x ≤ 0.3 and y may satisfy 0 ≤ y ≤ 0.5), and Ba(Ti 1-y Zr y )O3 (where y may satisfy 0 < y ≤ 0.5), but is not necessarily limited thereto.

[0074] The dielectric ceramic composition according to the embodiments of the present disclosure may have a dielectric constant greater than or equal to 2000 at room temperature.

[0075] The main component of the matrix material is not limited to any specific example, and the average particle diameter of the main component powder may be greater than or equal to 40 nm and less than or equal to 150 nm.

[0076] b) First sub-component

[0077] According to embodiments of this disclosure, the dielectric ceramic composition may necessarily include dysprosium (Dy) and terbium (Tb) as first secondary component elements, and may also include 0.0 mol% to 4.0 mol% of a first secondary component based on 100 mol% of the matrix material main component. The first secondary component includes an oxide or carbonate containing at least one element selected from the group consisting of yttrium (Y), holmium (Ho), erbium (Er), cerium (Ce), neodymium (Nd), promethium (Pm), europium (Eu), gadolinium (Gd), thulium (Tm), ytterbium (Yb), lutetium (Lu), and samarium (Sm) as the first secondary component elements. In one embodiment, the content of the oxide or carbonate comprising at least one element selected from the group consisting of Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu, and Sm as a first sub-component element may be at least greater than 0.0 mol%, greater than or equal to 0.1 mol%, greater than or equal to 0.5 mol%, greater than or equal to 1.0 mol%, greater than or equal to 1.5 mol%, greater than or equal to 2.0 mol%, greater than or equal to 2.5 mol%, greater than or equal to 3.0 mol%, or greater than or equal to 3.5 mol%. In one embodiment, the content of an oxide or carbonate of at least one element selected from the group consisting of Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu, and Sm as a first sub-component element may be less than or equal to 3.5 mol%, less than or equal to 3.0 mol%, less than or equal to 2.5 mol%, less than or equal to 2.0 mol%, less than or equal to 1.5 mol%, less than or equal to 1.0 mol%, or less than or equal to 0.5 mol%.

[0078] The first component can be used to prevent reliability degradation of multilayer ceramic capacitors using dielectric ceramic compositions in the embodiments of this disclosure.

[0079] When the content of the first component exceeds 4.0 mol%, the reliability may decrease, the dielectric constant of the dielectric ceramic composition may decrease, or the high-temperature withstand voltage characteristics may deteriorate.

[0080] According to embodiments of this disclosure, the molar ratio (Tb / Dy) of terbium (Tb) content to dysprosium (Dy) content can satisfy 0.15 ≤ Tb / Dy < 0.50.

[0081] Reliability, such as improved insulation resistance, can be improved by controlling the molar ratio (Tb / Dy) of terbium (Tb) to dysprosium (Dy) to satisfy 0.15≤Tb / Dy<0.50.

[0082] When the molar ratio of terbium (Tb) to dysprosium (Dy) (Tb / Dy) is less than 0.15, the effect of adding terbium (Tb) on improving reliability may not be significant. Furthermore, when the molar ratio of terbium (Tb) to dysprosium (Dy) (Tb / Dy) is 0, that is, when terbium (Tb) is not added as in the prior art, there is no effect on improving reliability, which may increase the defect rate.

[0083] When the molar ratio of terbium (Tb) to dysprosium (Dy) (Tb / Dy) is greater than or equal to 0.50, the insulation resistance may deteriorate due to semiconductorization.

[0084] Furthermore, the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), which is a 100 mol% matrix material, can be greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%.

[0085] Reliability, such as improved insulation resistance, can be improved by controlling the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), a main component of 100 mol% matrix material, to be greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%.

[0086] c) Second sub-component

[0087] According to embodiments of this disclosure, the dielectric ceramic composition may include oxides or carbonates comprising one or more elements selected from Mn, V, Cr, Fe, Ni, Co, Cu, and Zn as a second component.

[0088] As a second component, the content of oxides or carbonates selected from the group consisting of manganese (Mn), vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), and zinc (Zn) in 100 mol% of the matrix material powder can be from 0.1 mol% to 2.0 mol%. In one embodiment, the content of oxides or carbonates selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn as second component elements can be greater than or equal to 0.2 mol%, greater than or equal to 0.4 mol%, greater than or equal to 0.6 mol%, greater than or equal to 0.8 mol%, greater than or equal to 1.0 mol%, greater than or equal to 1.2 mol%, greater than or equal to 1.4 mol%, greater than or equal to 1.6 mol%, or greater than or equal to 1.8 mol%. In one embodiment, the content of oxides or carbonates of one or more elements selected from the group consisting of Mn, V, Cr, Fe, Ni, Co, Cu, and Zn as second sub-component elements may be less than or equal to 1.8 mol%, less than or equal to 1.6 mol%, less than or equal to 1.4 mol%, less than or equal to 1.2 mol%, less than or equal to 1.0 mol%, less than or equal to 0.8 mol%, less than or equal to 0.6 mol%, less than or equal to 0.4 mol%, or less than or equal to 0.2 mol%.

[0089] The second component can be used to lower the sintering temperature and improve the high-temperature withstand voltage characteristics of multilayer ceramic capacitors using dielectric ceramic compositions.

[0090] The content of the second sub-component and the content of the third to sixth sub-components, which will be described later, can be based on 100 mol% of the matrix material powder, and in particular, can be defined as the molar percentage (mol%) of metal ions contained in each sub-component.

[0091] When the content of the second component is less than 0.1 mol%, the sintering temperature may increase and the high-temperature pressure resistance may decrease slightly.

[0092] When the content of the second component is greater than or equal to 2.0 mol%, the high-temperature pressure resistance and room temperature resistivity may decrease.

[0093] In particular, the dielectric ceramic composition according to embodiments of the present disclosure may include a second sub-component having an amount of 0.1 mol% to 2.0 mol% based on 100 mol% of the matrix material main component, thereby enabling low-temperature sintering and improving high-temperature pressure resistance.

[0094] d) Third sub-component

[0095] According to embodiments of this disclosure, the dielectric ceramic composition may include a third sub-component, which includes an oxide or carbonate containing a magnesium (Mg) acceptor element in a fixed valence state.

[0096] The composition may include 0.0 mol% to 0.5 mol% of a third secondary component of titanium (Ti) based on 100 mol% of the matrix material. In one embodiment, the content of the third secondary component of titanium (Ti) based on 100 mol% of the matrix material may be at least greater than 0.0 mol%, greater than or equal to 0.1 mol%, greater than or equal to 0.2 mol%, greater than or equal to 0.3 mol%, or greater than or equal to 0.4 mol%. In another embodiment, the content of the third secondary component of titanium (Ti) based on 100 mol% of the matrix material may be less than or equal to 0.4 mol%, less than or equal to 0.3 mol%, or less than or equal to 0.2 mol%.

[0097] The third auxiliary component can be a fixed-valence acceptor element or a compound containing a fixed-valence acceptor element, and the third auxiliary component can act as an acceptor that reduces electron concentration. By adding 0.0 mol% to 0.5 mol% of the third auxiliary component, the effect of improving reliability due to n-type conversion can be maximized.

[0098] When the content of the third sub-component based on 100 mol% matrix material powder exceeds 0.5 mol%, the dielectric constant may decrease (this is not preferred).

[0099] However, according to embodiments of this disclosure, it is preferred to add 0.5 mol% of a third secondary component based on 100 mol% of the matrix material main component of titanium (Ti) to maximize the effect of improving reliability due to n-type, but is not necessarily limited thereto, and a small amount of the third secondary component less than 0.5 mol% may be added.

[0100] e) Fourth sub-component

[0101] According to embodiments of this disclosure, the dielectric ceramic composition may include a fourth sub-component, which includes an oxide or carbonate containing barium (Ba).

[0102] The dielectric ceramic composition may include a fourth sub-component of 0.0 mol% to 4.15 mol% based on 100 mol% of the matrix material main component, the fourth sub-component comprising an oxide or carbonate containing Ba. In one embodiment, the content of the fourth sub-component based on 100 mol% of the matrix material main component may be at least greater than 0.0 mol%, greater than or equal to 0.1 mol%, greater than or equal to 0.5 mol%, greater than or equal to 1.0 mol%, greater than or equal to 1.5 mol%, greater than or equal to 2.0 mol%, greater than or equal to 2.5 mol%, greater than or equal to 3.0 mol%, greater than or equal to 3.5 mol%, or greater than or equal to 4.0 mol%. In one embodiment, the content of the fourth secondary component based on the 100 mol% matrix material main component may be less than or equal to 4.0 mol%, less than or equal to 3.5 mol%, less than or equal to 3.0 mol%, less than or equal to 2.5 mol%, less than or equal to 2.0 mol%, less than or equal to 1.5 mol%, less than or equal to 1.0 mol%, or less than or equal to 0.5 mol%.

[0103] The content of the fourth sub-component can be based on the content of Ba element contained in the fourth sub-component, without distinguishing the form of additives such as oxides or carbonates.

[0104] In dielectric ceramic compositions, the fourth sub-component can be used to promote the sintering process, control the dielectric constant, etc., and when the content of the fourth sub-component based on 100 mol% of the matrix material main component exceeds 4.15 mol%, the dielectric constant may decrease or the sintering temperature may increase.

[0105] f) Fifth sub-component

[0106] According to embodiments of the present disclosure, the dielectric ceramic composition may include a fifth sub-component, which includes one or more elements selected from the group consisting of oxides and carbonates, wherein the oxides and carbonates include one or more elements selected from the group consisting of calcium (Ca) and zirconium (Zr).

[0107] The dielectric ceramic composition may include a fifth sub-component of 0.0 mol% to 20.0 mol% based on 100 mol% of the matrix material main component, the fifth sub-component comprising an oxide or carbonate containing at least one selected from the group consisting of Ca and Zr. In one embodiment, the content of the fifth sub-component based on 100 mol% of the matrix material main component may be at least greater than 0.0 mol%, greater than or equal to 0.1 mol%, greater than or equal to 0.5 mol%, greater than or equal to 1.0 mol%, greater than or equal to 2.5 mol%, greater than or equal to 5.0 mol%, greater than or equal to 10.0 mol%, or greater than or equal to 15.0 mol%. In another embodiment, the content of the fifth sub-component based on 100 mol% of the matrix material main component may be less than or equal to 15.0 mol%, less than or equal to 10.0 mol%, less than or equal to 5.0 mol%, less than or equal to 2.5 mol%, less than or equal to 1.0 mol%, or less than or equal to 0.5 mol%.

[0108] The content of the fifth sub-component can be based on the content of one or more elements between Ca and Zr contained in the fifth sub-component, without distinguishing the form of additives such as oxides or carbonates.

[0109] In dielectric ceramic compositions, the fifth sub-component can form a core-shell structure and can be used to improve dielectric constant and reliability. When based on 100 mol% of the matrix material as the main component, a dielectric ceramic composition containing 20.0 mol% or less of the fifth sub-component can be provided, achieving a relatively high dielectric constant and having improved high-temperature withstand voltage properties.

[0110] When the content of the fifth sub-component based on a 100 mol% matrix material exceeds 20.0 mol%, the room temperature dielectric constant may decrease, and the high temperature withstand voltage characteristics may also decrease.

[0111] g) Sixth sub-component

[0112] According to embodiments of the present disclosure, the dielectric ceramic composition may include a sixth sub-component, which includes an oxide comprising at least one element selected from the group consisting of silicon (Si) and aluminum (Al) or a glass compound comprising Si.

[0113] The dielectric ceramic composition may further include a sixth sub-component of 0.0 mol% to 4.0 mol% based on 100 mol% of the matrix material main component, wherein the sixth sub-component comprises an oxide containing at least one element between Si and Al or a glass compound containing Si. In one embodiment, the content of the sixth sub-component based on 100 mol% of the matrix material main component may be at least greater than 0.0 mol%, greater than or equal to 0.1 mol%, greater than or equal to 0.5 mol%, greater than or equal to 1.5 mol%, greater than or equal to 2.0 mol%, greater than or equal to 2.5 mol%, greater than or equal to 3.0 mol%, or greater than or equal to 3.5 mol%. In another embodiment, the content of the sixth sub-component based on 100 mol% of the matrix material main component may be less than or equal to 3.5 mol%, less than or equal to 3.0 mol%, less than or equal to 2.5 mol%, less than or equal to 2.0 mol%, less than or equal to 1.5 mol%, less than or equal to 1.0 mol%, or less than or equal to 0.5 mol%.

[0114] The content of the sixth sub-component can be based on the content of one or more elements between Si and Al included in the sixth sub-component, without distinguishing the form of additives such as glass compounds or oxides.

[0115] The sixth component can be used to lower the sintering temperature and to improve the high-temperature withstand voltage characteristics of multilayer ceramic capacitors using dielectric ceramic compositions.

[0116] When the content of the sixth sub-component based on the 100 mol% matrix material main component exceeds 4.0 mol%, problems such as deterioration of sintering characteristics and density, and formation of a second phase may occur (this is not preferred).

[0117] In particular, according to embodiments of the present disclosure, since the dielectric ceramic composition contains 4.0 mol% or less Al, grain growth can be uniformly controlled, thereby improving withstand voltage characteristics and reliability, and also improving DC bias.

[0118] In the following description, the present disclosure will be described in more detail with reference to embodiments and comparative examples, and embodiments are provided to aid in understanding the present disclosure, and the scope of the embodiments is not limited thereto.

[0119] (Example)

[0120] In an embodiment, in order to form a dielectric layer, a dielectric paste is prepared by adding additives such as Dy, Tb, Al, Mg, Mn, etc., and organic solvents such as binders and ethanol to a dielectric raw material powder containing barium titanate (BaTiO3) powder and performing a wet mixing process. Then, a ceramic green sheet is prepared by coating the surface of a carrier film with the dielectric paste and drying the coated paste, and a dielectric layer is formed.

[0121] In this case, all elemental additives are added in a monodisperse form based on barium titanate at a size of 40% or less.

[0122] Specifically, the sum of the contents of dysprosium (Dy) and terbium (Tb) in the rare earth elements of titanium (Ti), which is a 100 mol% matrix material, is less than or equal to 1.5 mol%.

[0123] In the embodiment, the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), which is a 100 mol% matrix material, is 1.5 mol%, and the molar ratio (Tb / Dy) of terbium (Tb) to dysprosium (Dy) is adjusted to be greater than or equal to 0.15 and less than 0.5.

[0124] Ceramic green sheets with a thickness of several μm are prepared from a slurry containing a mixture of ceramic powder, binder and solvent by applying a doctor blade method to the slurry.

[0125] Next, a conductive paste for the internal electrode is prepared comprising 40 to 50 parts by weight of nickel powder, wherein the average size of the nickel particles is in the range of 0.1 μm to 0.2 μm.

[0126] The green sheet is coated with conductive paste for the internal electrode using a screen printing process. The green sheets with the internal electrode pattern are then stacked to form a laminate. The laminate is then pressed and cut.

[0127] The binder is then removed by heating the cut laminate, and the laminate is sintered in a high-temperature reducing atmosphere to form a ceramic body.

[0128] In the sintering process, the sintering process is carried out for two hours at 1100°C to 1200°C in a reducing atmosphere (0.1% H2 / 99.9% N2, H2O / H2 / N2 atmosphere), followed by re-oxidation at 1000°C in a nitrogen (N2) atmosphere for three hours, and then heat treatment.

[0129] Next, copper (Cu) paste is used to perform end-sealing and electrode sintering processes on the sintered ceramic body, and external electrodes are prepared.

[0130] Furthermore, after the sintering process, the thickness of the dielectric layer 111, the first inner electrode 121, and the second inner electrode 122 in the ceramic body 110 is less than or equal to 0.45 μm.

[0131] (Compare Example 1)

[0132] In Comparative Example 1, the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), a matrix material with a main component of 100 mol%, is 1.8 mol%, and other manufacturing processes are the same as those in the above embodiments.

[0133] (Compare Example 2)

[0134] In Comparative Example 2, the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), a matrix material with a main component of 100 mol%, is 2.1 mol%, and other manufacturing processes are the same as those in the above embodiments.

[0135] (Compare Example 3)

[0136] In Comparative Example 3, dysprosium (Dy) is added without terbium (Tb), as is the case with dielectric ceramic compositions in the prior art, and the other manufacturing processes are the same as those in the above embodiments.

[0137] (Compare Example 4)

[0138] In Comparative Example 4, terbium (Tb) and dysprosium (Dy) were added in an amount such that the molar ratio (Tb / Dy) of terbium (Tb) to dysprosium (Dy) was less than 0.1, and other manufacturing processes were the same as those in the above embodiments.

[0139] (Compare Example 5)

[0140] In Comparative Example 5, terbium (Tb) and dysprosium (Dy) were added in an amount that made the molar ratio (Tb / Dy) of terbium (Tb) to dysprosium (Dy) greater than or equal to 0.5, and other manufacturing processes were the same as those in the above embodiments.

[0141] Temperature characteristics and high accelerated life (HALT) tests were performed on the examples (samples of the prototype multilayer ceramic capacitors (MLCCs) manufactured as described above) and comparative examples 1 to 5 to assess the defect rate.

[0142] The temperature coefficient of capacitance (TCC) is measured by temperature characteristics. The X5R temperature characteristic standard should meet ±15% capacitance based on a 25°C capacitor in the range of -55°C to 85°C, and the X6S temperature characteristic standard should meet ±22% capacitance based on a 25°C capacitor in the range of -55°C to 105°C.

[0143] In the High Accelerated Life Test (HALT), 40 multilayer ceramic capacitor plates were mounted on a substrate in each sample, and the defect rate was measured for 12 hours at 125°C with a voltage of 20V (DC).

[0144] Table 1 below shows the temperature characteristics of the prototype multilayer ceramic capacitor (MLCC) sheet in the experimental examples (examples and comparative examples 1 and 2).

[0145] Table 1

[0146]

[0147]

[0148] Referring to Table 1, in the cases of Comparative Example 1 and Comparative Example 2 (based on the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), the main component of the matrix material, which is 100 mol%, exceeds 1.5 mol%), it can be seen that not only are the X5R temperature characteristics not satisfied, but the X6S temperature characteristics are also not satisfied.

[0149] On the other hand, embodiments of this disclosure illustrate cases where the sum of the contents of dysprosium (Dy) and terbium (Tb) in titanium (Ti), a matrix material with a main component of 100 mol%, is less than or equal to 1.5 mol%. It can be seen that not only are the X6S temperature characteristics satisfied, but also the X5R temperature characteristics are satisfied, and the reliability improvement is excellent.

[0150] Figure 3 This is a graph showing the results of high-acceleration life tests according to embodiments and comparative examples of this disclosure.

[0151] Reference Figure 3 In the comparison example 3 of this disclosure (e.g.) Figure 3 In (a)), it can be seen that the components of the dielectric ceramic composition in the prior art are prepared by adding only dysprosium (Dy) without adding terbium (Tb). The number of defects obtained by high accelerated life testing is 5 (which is relatively high).

[0152] Comparison Example 4 in this disclosure (e.g.) Figure 3 In (b)), the molar ratio (Tb / Dy) of terbium (Tb) to dysprosium (Dy) is less than 0.15. The number of defects obtained through high accelerated life testing is 12 (which is relatively high).

[0153] This is because the amount of terbium (Tb) added is less than that of dysprosium (Dy), so the effect of adding terbium (Tb) on improving reliability may not be significant.

[0154] On the other hand, in embodiments of this disclosure (such as...) Figure 3 In (c)), the molar ratio (Tb / Dy) of terbium (Tb) to dysprosium (Dy) satisfies greater than or equal to 0.15 and less than 0.5. The number of defects obtained through high accelerated life testing is 0 (which is relatively low). Therefore, reliability is improved.

[0155] Furthermore, in Comparative Example 5 of this disclosure (such as...) Figure 3 In (d), the molar ratio (Tb / Dy) of terbium (Tb) to dysprosium (Dy) was greater than or equal to 0.5, and almost all samples were found to be defective in reliability.

[0156] When the molar ratio of terbium (Tb) content to dysprosium (Dy) content (Tb / Dy) is greater than or equal to 0.50, it is believed that the insulation resistance may decrease due to semiconductorization.

[0157] As described above, according to embodiments of the present disclosure, the dielectric ceramic composition in the dielectric layer contained in the ceramic body contains terbium (Tb) (a new rare earth element) as a secondary element, and its content can be controlled to improve reliability such as improved insulation resistance.

[0158] While exemplary 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 invention as defined by the appended claims.

Claims

1. A dielectric ceramic composition comprising: Barium titanate-based matrix materials: main and secondary components The by-components include trivalent lanthanide rare earth elements A and terbium, which are rare earth elements. Among them, the trivalent lanthanide rare earth element A is dysprosium. Specifically, the sum of the contents of trivalent lanthanide rare earth element A and terbium in titanium, which is the main component of the matrix material at 100 mol%, is greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%. The molar ratio of terbium content to the content of the trivalent lanthanide rare earth element A, Tb / A, satisfies 0.15 ≤ Tb / A < 0.50, and The dielectric ceramic composition comprises a fifth secondary component of 100 mol% matrix material, which is greater than 0.0 mol% and less than or equal to 20.0 mol%, and the fifth secondary component comprises an oxide or carbonate containing at least one element between Ca and Zr.

2. A dielectric ceramic composition comprising: Barium titanate-based matrix materials: main and secondary components The by-components include trivalent lanthanide rare earth elements A and terbium, which are rare earth elements. Among them, the trivalent lanthanide rare earth element A is dysprosium. Specifically, the sum of the contents of trivalent lanthanide rare earth element A and terbium in titanium, which is the main component of the matrix material at 100 mol%, is greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%. The molar ratio of terbium content to the content of the trivalent lanthanide rare earth element A, Tb / A, satisfies 0.15 ≤ Tb / A < 0.50, and The dielectric ceramic composition comprises a sixth sub-component of greater than 0.0 mol% and less than or equal to 4.0 mol% based on 100 mol% of the matrix material main component, wherein the sixth sub-component comprises an oxide containing at least one element between Si and Al or a glass compound containing Si.

3. The dielectric ceramic composition according to claim 1 or claim 2, wherein, The dielectric ceramic composition further includes a first secondary component of greater than 0.0 mol% and less than or equal to 4.0 mol% based on 100 mol% of the matrix material main component, the first secondary component comprising an oxide or carbonate containing at least one element selected from Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu and Sm.

4. The dielectric ceramic composition according to claim 1 or claim 2, wherein, The dielectric ceramic composition comprises 0.1 mol% to 2.0 mol% of a second component based on 100 mol% of the matrix material as the main component, the second component comprising an oxide or carbonate containing at least one element selected from Mn, V, Cr, Fe, Ni, Co, Cu, and Zn.

5. The dielectric ceramic composition according to claim 1 or claim 2, wherein, The dielectric ceramic composition comprises a fourth secondary component of greater than 0.0 mol% and less than or equal to 4.15 mol% based on 100 mol% of the matrix material primary component, the fourth secondary component comprising oxides or carbonates containing Ba.

6. The dielectric ceramic composition according to claim 1 or claim 2, wherein, The dielectric ceramic composition comprises a third sub-component of greater than 0.0 mol% and less than or equal to 0.5 mol% of titanium, which is the main component of the matrix material at 100 mol%, and the third sub-component comprises an oxide or carbonate containing a fixed-valence acceptor element Mg.

7. The dielectric ceramic composition according to claim 1 or claim 2, wherein, The dielectric ceramic composition does not contain Mg.

8. A multilayer ceramic capacitor, comprising: A ceramic body includes a dielectric layer and a first inner electrode and a second inner electrode, wherein the first inner electrode and the second inner electrode are arranged opposite to each other and the dielectric layer is located between them; as well as A first external electrode and a second external electrode are provided, wherein the first external electrode is electrically connected to the first internal electrode, and the second external electrode is electrically connected to the second internal electrode, and the first external electrode and the second external electrode are disposed on the outer surface of the ceramic body. The dielectric layer comprises a dielectric ceramic composition. The dielectric ceramic composition comprises a barium titanate-based matrix material as the main component and secondary components, wherein the secondary components include trivalent lanthanide rare earth elements A and terbium as rare earth elements. Among them, the trivalent lanthanide rare earth element A is dysprosium. Specifically, the sum of the contents of trivalent lanthanide rare earth element A and terbium in titanium, which is the main component of the matrix material at 100 mol%, is greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%. The molar ratio of terbium content to the content of the trivalent lanthanide rare earth element A, Tb / A, satisfies 0.15 ≤ Tb / A < 0.50, and The dielectric ceramic composition comprises a fifth secondary component of 100 mol% matrix material, which is greater than 0.0 mol% and less than or equal to 20.0 mol%, and the fifth secondary component comprises an oxide or carbonate containing at least one element between Ca and Zr.

9. A multilayer ceramic capacitor, comprising: A ceramic body includes a dielectric layer and a first inner electrode and a second inner electrode, wherein the first inner electrode and the second inner electrode are arranged opposite to each other and the dielectric layer is located between them; as well as A first external electrode and a second external electrode are provided, wherein the first external electrode is electrically connected to the first internal electrode, and the second external electrode is electrically connected to the second internal electrode, and the first external electrode and the second external electrode are disposed on the outer surface of the ceramic body. The dielectric layer comprises a dielectric ceramic composition. The dielectric ceramic composition comprises a barium titanate-based matrix material as the main component and secondary components, wherein the secondary components include trivalent lanthanide rare earth elements A and terbium as rare earth elements. Among them, the trivalent lanthanide rare earth element A is dysprosium. Specifically, the sum of the contents of trivalent lanthanide rare earth element A and terbium in titanium, which is the main component of the matrix material at 100 mol%, is greater than or equal to 0.2 mol% and less than or equal to 1.5 mol%. The molar ratio of terbium content to the content of the trivalent lanthanide rare earth element A, Tb / A, satisfies 0.15 ≤ Tb / A < 0.50, and The dielectric ceramic composition comprises a sixth sub-component of greater than 0.0 mol% and less than or equal to 4.0 mol% based on 100 mol% of the matrix material main component, wherein the sixth sub-component comprises an oxide containing at least one element between Si and Al or a glass compound containing Si.

10. The multilayer ceramic capacitor as claimed in claim 8 or claim 9, wherein, The dielectric ceramic composition further includes a first secondary component of greater than 0.0 mol% and less than or equal to 4.0 mol% based on 100 mol% of the matrix material main component, the first secondary component comprising an oxide or carbonate containing at least one element selected from Y, Ho, Er, Ce, Nd, Pm, Eu, Gd, Tm, Yb, Lu and Sm.

11. The multilayer ceramic capacitor as claimed in claim 8 or claim 9, wherein, The dielectric ceramic composition comprises 0.1 mol% to 2.0 mol% of a second component based on 100 mol% of the matrix material as the main component, the second component comprising an oxide or carbonate containing at least one element selected from Mn, V, Cr, Fe, Ni, Co, Cu, and Zn.

12. The multilayer ceramic capacitor as claimed in claim 8 or claim 9, wherein, The dielectric ceramic composition comprises a fourth secondary component of greater than 0.0 mol% and less than or equal to 4.15 mol% based on 100 mol% of the matrix material primary component, the fourth secondary component comprising oxides or carbonates containing Ba.

13. The multilayer ceramic capacitor as claimed in claim 8 or claim 9, wherein, The dielectric ceramic composition comprises a third sub-component of greater than 0.0 mol% and less than or equal to 0.5 mol% of titanium, which is the main component of the matrix material at 100 mol%, and the third sub-component comprises an oxide or carbonate containing a fixed-valence acceptor element Mg.

14. The multilayer ceramic capacitor as claimed in claim 8 or claim 9, wherein, The dielectric ceramic composition does not contain Mg.

15. The multilayer ceramic capacitor as claimed in claim 8 or claim 9, wherein, The thickness of the dielectric layer is less than or equal to 0.45 μm, and the thicknesses of the first inner electrode and the second inner electrode are less than or equal to 0.45 μm.

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