DIELECTRIC CERAMIC COMPOSITION, MULTILAYER CERAMIC CAPACITOR CONTAINING THE SAME, AND METHOD FOR MANUFACTURING MULTILAYER CERAMIC CAPACITOR

Abstract

A dielectric ceramic composition contains a first main ingredient of BaTiO.sub.3 and a second main ingredient of BaTi.sub.2O.sub.5, and a base material powder containing the first and second main ingredients is represented by (1-x)BaTiO.sub.3-xBaTi.sub.2O.sub.5 and x satisfies 0.1x0.8. The dielectric ceramic composition may include additional accessory ingredients, and may be used to form ceramic sheets having internal electrodes of a multilayer ceramic capacitor disposed thereon.

Claims

1. A dielectric ceramic composition comprising a first main ingredient of BaTiO.sub.3 and a second main ingredient of BaTi.sub.2O.sub.5, wherein a base material powder containing the first and second main ingredients is represented by (1-x)BaTiO.sub.3-xBaTi.sub.2O.sub.5, and x satisfies 0.1x0.8.

2. The dielectric ceramic composition of claim 1, further comprising a first accessory ingredient, wherein the first accessory ingredient contains oxides or carbonates of one or more variable valence acceptor elements selected from the group consisting of Manganese (Mn) , vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), and zinc (Zn), and a sum of contents of the one or more variable valence acceptor elements contained in the first accessory ingredient is 0.2 at % to 5.0 at %.

3. The dielectric ceramic composition of claim 1, further comprising a second accessory ingredient, wherein the second accessory ingredient contains one or more selected from the group consisting of oxides and carbonates of Ba, and a content of the second accessory ingredient is 0.2 mol to 10.0 mol based on 100 mol of the base material powder.

4. The dielectric ceramic composition of claim 1, further comprising a third accessory ingredient, wherein the third accessory ingredient contains one or more selected from the group consisting of oxides of Si, carbonates of Si, and glass containing Si, and a content of the third accessory ingredient is 0.2 mol to 5.0 mol based on 100 mol of the base material powder.

5. The dielectric ceramic composition of claim 1, further comprising a fourth accessory ingredient, wherein the fourth accessory ingredient contains oxides or carbonates of one or more rare earth elements selected from the group consisting of Y, Dy, Ho, La, Ce, Nd, Sm, Gd, and Er, and a sum of contents of the one or more rare earth elements contained in the fourth accessory ingredient is 0.5 at % to 10.0 at %.

6. The dielectric ceramic composition of claim 1, further comprising a fifth accessory ingredient, wherein the fifth accessory ingredient contains one or more selected from the group consisting of oxides and carbonates of a fixed-valence acceptor element including Mg, and a content of the fifth accessory ingredient is 0.5 mol to 5.0 mol based on 100 mol of the base material powder.

7. A multilayer ceramic capacitor comprising: a ceramic body including dielectric layers and internal electrodes; and external electrodes disposed on an outer portion of the ceramic body and connected to the internal electrodes, wherein the dielectric layers include a first crystal grain and a second crystal grain, the first crystal grain is a crystal grain in which a Ti/Ba content ratio is less than 1.5, the second crystal grain is a crystal grain in which a Ti/Ba content ratio is 1.5 to 2.5, and an area ratio of the second crystal grain to a total area is 9.5% to 81.4%.

8. The multilayer ceramic capacitor of claim 7, wherein the dielectric layer contains a first main ingredient of BaTiO.sub.3 and a second main ingredient of BaTi.sub.2O.sub.5, and a base material powder containing the first and second main ingredients is represented by (1-x) BaTiO.sub.3-xBaTi.sub.2O.sub.5, and x satisfies 0.1x0.8.

9. The multilayer ceramic capacitor of claim 7, wherein the internal electrodes contain Ni.

10. The multilayer ceramic capacitor of claim 7, wherein the multilayer ceramic capacitor has room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature withstand voltage at 200 C. of 50V/m or more, temperature coefficient of capacitance (TCC) at 150 C. less than 15%, TCC at 200 C. less than 22%, and room-temperature permittivity of 150 or more.

11. A method for manufacturing a multilayer ceramic capacitor, the method comprising: manufacturing a plurality of ceramic sheets using a base material powder containing a first main ingredient of BaTiO.sub.3 and a second main ingredient of BaTi.sub.2O.sub.5; printing an internal electrode on two or more of the ceramic sheets using a conductive paste, and stacking and compressing the ceramic sheets to manufacture a compressed bar; cutting the compressed bar to manufacture a chip; and sintering the chip under a reduction atmosphere, wherein the base material powder is represented by (1-x) BaTiO.sub.3-xBaTi.sub.2O.sub.5, and x satisfies 0.1x0.8.

12. The method of claim 11, wherein the sintering of the chip is performed under 1.0% of H.sub.2/99% of N.sub.2 atmosphere.

13. The method of claim 11, wherein the sintering of the chip is performed at 1200 C.

14. A dielectric ceramic composition comprising a first crystal grain in which a Ti/Ba content ratio is less than 1.5, and a second crystal grain in which a Ti/Ba content ratio is 1.5 to 2.5, wherein an area ratio of the second crystal grain to a total area is 9.5% to 81.4%.

15. The dielectric ceramic composition of claim 14, wherein the dielectric ceramic composition contains a first main ingredient of BaTiO.sub.3 and a second main ingredient of BaTi.sub.2O.sub.5, and a base material powder containing the first and second main ingredients is represented by (1-x) BaTiO.sub.3-xBaTi.sub.2O.sub.5, and x satisfies 0.1x0.8.

16. The dielectric ceramic composition of claim 14, further comprising a first accessory ingredient, wherein the first accessory ingredient contains oxides or carbonates of one or more variable valence acceptor elements selected from the group consisting of Manganese (Mn) , vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), and zinc (Zn), and a sum of contents of the one or more variable valence acceptor elements contained in the first accessory ingredient is 0.2 a% to 5.0 at %.

17. The dielectric ceramic composition of claim 14, further comprising a second accessory ingredient, wherein the second accessory ingredient contains one or more selected from the group consisting of oxides and carbonates of Ba, and a content of the second accessory ingredient is 0.2 mol to 10.0 mol based on 100 mol of the base material powder.

18. The dielectric ceramic composition of claim 14, further comprising a third accessory ingredient, wherein the third accessory ingredient contains one or more selected from the group consisting of oxides of Si, carbonates of Si, and glass containing Si, and a content of the third accessory ingredient is 0.2 mol to 5.0 mol based on 100 mol of the base material powder.

19. The dielectric ceramic composition of claim 14, further comprising a fourth accessory ingredient, wherein the fourth accessory ingredient contains oxides or carbonates of one or more rare earth elements selected from the group consisting of Y, Dy, Ho, La, Ce, Nd, Sm, Gd, and Er, and a sum of contents of the one or more rare earth elements contained in the fourth accessory ingredient is 0.5 at % to 10.0 at %.

20. The dielectric ceramic composition of claim 14, further comprising a fifth accessory ingredient, wherein the fifth accessory ingredient contains one or more selected from the group consisting of oxides and carbonates of a fixed-valence acceptor element including Mg, and a content of the fifth accessory ingredient is 0.5 mol to 5.0 mol based on 100 mol of the base material powder.

21. A multilayer ceramic capacitor comprising: a ceramic body including dielectric layers and internal electrodes; and external electrodes disposed on an outer portion of the ceramic body and connected to the internal electrodes, wherein the dielectric layers include a base material powder containing a first main ingredient of BaTiO.sub.3 and a second main ingredient of BaTi.sub.2O.sub.5, the base material powder is represented by (1-x)BaTiO.sub.3-xBaTi.sub.2O.sub.5, and x satisfies 0.1x0.8.

22. The multilayer ceramic capacitor of claim 21, wherein the dielectric layers further comprise a first accessory ingredient containing oxides or carbonates of one or more variable valence acceptor elements selected from the group consisting of Manganese (Mn), vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), and zinc (Zn), and a sum of contents of the one or more variable valence acceptor elements contained in the first accessory ingredient is 0.2 at % to 5.0 at %.

23. The multilayer ceramic capacitor of claim 21, wherein the dielectric layers further comprise a second accessory ingredient containing one or more selected from the group consisting of oxides and carbonates of Ba, and a content of the second accessory ingredient is 0.2 mol to 10.0 mol based on 100 mol of the base material powder.

24. The multilayer ceramic capacitor of claim 21, wherein the dielectric layers further comprise a third accessory ingredient containing one or more selected from the group consisting of oxides of Si, carbonates of Si, and glass containing Si, and a content of the third accessory ingredient is 0.2 mol to 5.0 mol based on 100 mol of the base material powder.

25. The multilayer ceramic capacitor of claim 21, wherein the dielectric layers further comprise a fourth accessory ingredient containing oxides or carbonates of one or more rare earth elements selected from the group consisting of Y, Dy, Ho, La, Ce, Nd, Sm, Gd, and Er, and a sum of contents of the one or more rare earth elements contained in the fourth accessory ingredient is 0.5 at % to 10.0 at %.

26. The multilayer ceramic capacitor of claim 21, wherein the dielectric layers further comprise a fifth accessory ingredient containing one or more selected from the group consisting of oxides and carbonates of a fixed-valence acceptor element including Mg, and a content of the fifth accessory ingredient is 0.5 mol to 5.0 mol based on 100 mol of the base material powder.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and other aspects, features, and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0026] FIG. 1 is a schematic view illustrating a microstructure composed of a first crystal grain and a second crystal grain as may be used in the dielectric ceramic compositions discussed herein;

[0027] FIG. 2 is a schematic perspective view illustrating a multilayer ceramic capacitor according to an exemplary embodiment; and

[0028] FIG. 3 is a schematic cross-sectional view illustrating the multilayer ceramic capacitor taken along line of FIG. 2.

DETAILED DESCRIPTION

[0029] Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings.

[0030] The present disclosure relates to a dielectric ceramic composition. Examples of electronic components containing the dielectric ceramic composition include capacitors, inductors, piezoelectric elements, varistors, thermistors, or the like. Hereinafter, the dielectric ceramic composition and a multilayer ceramic capacitor as an example of the electronic component will be described.

[0031] In the present disclosure, a content of each accessory ingredient of the dielectric ceramic composition may be represented by the number of moles or at % of each accessory ingredient based on 100 mol of a base material powder.

[0032] In describing the content of the accessory ingredient in the present disclosure, at % may mean a percentage value of the number of desired atoms of each accessory ingredient with respect to the number of Ba atoms contained in 1 mol of the base material powder.

[0033] The desired atoms may mean a variable valence acceptor atom, a fixed-valence acceptor atom, a rare earth metal atom, and the like.

[0034] A dielectric ceramic composition according to an exemplary embodiment may contain a first main ingredient of BaTiO.sub.3 and a second main ingredient of BaTi.sub.2O.sub.5, wherein a base material powder containing the first and second main ingredients is represented by (1-x)BaTiO.sub.3-xBaTi.sub.2O.sub.5, and x satisfies 0.1x0.8.

[0035] The dielectric ceramic composition according to the exemplary embodiment in the present disclosure may satisfy the X8R (55 C.150 C., C/C015%) or X9S (55 C.200 C., C/C022%) characteristics specified by the Electronic Industries Association (EIA) standard.

[0036] In more detail, according to the exemplary embodiment, there is provided a dielectric ceramic composition capable of using Ni as a material of the internal electrodes and maintaining insulation resistance even in a case in which the dielectric ceramic composition is sintered under a reduction atmosphere at which Ni is not oxidized.

[0037] Further, the present disclosure may provide a multilayer ceramic capacitor using the dielectric ceramic composition, such that characteristics such as high permittivity, high insulation resistance, and a high Curie temperature may be simultaneously implemented.

[0038] Particularly, the desired characteristics of the present disclosure may be implemented by using the dielectric ceramic composition capable of containing BaTiO.sub.3 having high permittivity and BaTi.sub.2O.sub.5 having a high Curie temperature and being sintered under a reduction atmosphere to prepare a sample in a form of a composite composed of two kinds of crystal grains having different compositions from each other in a single sintered body, and controlling an area ratio between these two crystal grains.

[0039] Hereinafter, each ingredient of the dielectric ceramic composition according to the exemplary embodiment will be described in more detail.

[0040] a) Base Material Powder

[0041] The dielectric ceramic composition according to the exemplary embodiment may contain the first main ingredient of BaTiO.sub.3 and the second main ingredient of BaTi.sub.2O.sub.5, wherein the base material powder containing the first and second main ingredients is represented by (1-x) BaTiO.sub.3-xBaTi.sub.2O.sub.5, and x satisfies 0.1x0.8.

[0042] The first main ingredient may be represented by BaTiO.sub.3, wherein BaTiO.sub.3, a material used in a general dielectric base material, may be a ferroelectric material having a Curie temperature of about 125 C. or so.

[0043] As the first main ingredient, ingredients such as (Ba.sub.1-xCa.sub.x) (Ti.sub.1-yCa.sub.y)O.sub.3, Ba(Ti.sub.1-yZr.sub.y)O.sub.3 in which Ca, Zr, or the like is partially solid-dissolved, or the like, in addition to the ingredient of BaTiO.sub.3 may also be used.

[0044] The second main ingredient may be represented by BaTi.sub.2O.sub.5.

[0045] That is, in the base material powder of the dielectric ceramic composition according to the exemplary embodiment, materials represented by BaTiO.sub.3 having high permittivity and BaTi.sub.2O.sub.5 having a high Curie temperature may be mixed with each other in a predetermined ratio.

[0046] Since the dielectric ceramic composition according to the exemplary embodiment uses the base material powder prepared by mixing the first and second main ingredients at a predetermined ratio as described above, the dielectric ceramic composition may be sintered under the reduction atmosphere.

[0047] FIG. 1 is a schematic view illustrating a microstructure composed of a first crystal grain and a second crystal grain, and positions P1, P2, P3, and P4 for analyzing contents of Ba and Ti in each crystal grain by scanning transmission electron microscopy (STEM)/wavelength dispersive X-ray spectroscopy (WDS) or STEM/electron energy loss spectroscopy (EELS).

[0048] Referring to FIG. 1, a microstructure of a dielectric layer manufactured using the dielectric ceramic composition according to the exemplary embodiment (under the reduction atmosphere at a sintering temperature of 1200 C.) may include a first crystal grain in which a Ti/Ba content ratio is less than 1.5 and a second crystal grain in which the Ti/Ba content ratio is 1.5 to 2.5.

[0049] Contents of Ti and Ba in a single crystal grain may be obtained by measuring contents (at %) of Ti and Ba at each of the points P1 to P4 and calculating average values of the measured contents at the four positions.

[0050] A dielectric layer and a multilayer ceramic capacitor using the dielectric ceramic composition according to the exemplary embodiment may simultaneously have the characteristics such as high permittivity, high insulation resistance, and high Curie temperature.

[0051] More specifically, since in the dielectric layer manufactured using the dielectric ceramic composition according to the exemplary embodiment and a multilayer ceramic capacitor including the dielectric layers, an area ratio of the second crystal grain to a total area is 9.5 to 81.4%, all of the desired characteristics of the present disclosure, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, and room-temperature permittivity of 150 or more, may be simultaneously provided.

[0052] Further, since in the dielectric layer manufactured using the dielectric ceramic composition according to the exemplary embodiment and a multilayer ceramic capacitor including the dielectric layers, the area ratio of the second crystal grain to the total area is 9.5 to 81.4%, the X8R (55 C.150 C., C/C015%) or X9S (55 C.200 C., C/C022%) characteristics specified by the Electronic Industries Association (EIA) standard may be satisfied.

[0053] In a case in which the area ratio of the second crystal grain to the total area is less than 9.5%, the X8R (55 C.150 C., C/C015%) or X9S (55 C.200 C., C/C022%) characteristics specified by the Electronic Industries Association (EIA) standard may not be satisfied. Furthermore, in a case in which the area ratio of the second crystal grain to the total area is more than 81.4%, room-temperature permittivity may be less than 150.

[0054] That is, in a case in which the area ratio of the second crystal grain to the total area is out of the range of 9.5% to 81.4%, the desired characteristics of the present disclosure may not be provided.

[0055] The base material powder is not particularly limited, but may have an average particle size of 300 nm or less.

[0056] b) First Accessory Ingredient

[0057] According to the exemplary embodiment, the dielectric ceramic composition may further contain an oxide or carbonate containing one of Manganese (Mn), vanadium (V), chromium (Cr), iron (Fe), nickel (Ni), cobalt (Co), copper (Cu), and zinc (Zn), as a first accessory ingredient. For example, the first accessory ingredient may be MnO.sub.2 or V.sub.2O.sub.5.

[0058] Here, Mn, V, Cr, Fe, Ni, Co, Cu, and Zn are variable valence acceptors.

[0059] The first accessory ingredient may be provided in a ratio of 0.2 mol to 5.0 mol based on 100 mol of the base material powder. Alternatively, the first accessory ingredient may be provided so that a sum of contents of one or more atoms selected among Mn, V, Cr, Fe, Ni, Co, Cu, and Zn, contained in the first accessory ingredient, is in a range of 0.2 at % to 5.0 at %.

[0060] The first accessory ingredient may serve to decrease a sintering temperature of a multilayer ceramic capacitor using the dielectric ceramic composition, and improve high-temperature withstand voltage characteristics.

[0061] In a case in which the content of the first accessory ingredient is less than 0.2 mol based on 100 mol of the base material powder, high-temperature withstand voltage characteristics may be deteriorated, and in a case in which the content of the first accessory ingredient is more than 5.0 mol based on 100 mol of the base material powder, high-temperature withstand voltage characteristics may also be deteriorated.

[0062] That is, the dielectric ceramic composition according to the exemplary embodiment may further contain the first accessory ingredient in a content of 0.2 mol to 5.0 mol, such that all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, temperature coefficient of capacitance (TCC) (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, may be simultaneously provided.

[0063] In this case, the area ratio of the second crystal grain to the total area may also be 9.5% to 81.4%, as described below.

[0064] c) Second Accessory Ingredient

[0065] According to the exemplary embodiment, the dielectric ceramic composition may contain a second accessory ingredient containing one or more selected from the group consisting of oxides and carbonates of Ba. For example, the second accessory ingredient may be BaCO.sub.3.

[0066] The second accessory ingredient may be provided in a ratio of 0.2 mol to 10.0 mol based on 100 mol of the base material powder.

[0067] In a case in which the second accessory ingredient is not added or is excessively added, a sintering density may be decreased, such that the high-temperature withstand voltage may be decreased to be less than 50V/m.

[0068] In a case in which the second accessory ingredient is provided in a ratio of 0.2 mol to 10.0 mol based on 100 mol of the base material powder, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, may be simultaneously provided.

[0069] In this case, the area ratio of the second crystal grain to the total area may also be 9.5% to 81.4%, as described below.

[0070] d) Third Accessory Ingredient

[0071] According to the exemplary embodiment, the dielectric ceramic composition may contain a third accessory ingredient containing one or more selected from the group consisting of oxides of Si, carbonates of Si, and glass containing Si.

[0072] The third accessory ingredient may be provided in a ratio of 0.2 mol to 5.0 mol based on 100 mol of the base material powder.

[0073] In a case in which the content of the third accessory ingredient is less than 0.2 mol based on 100 mol of the base material powder of the dielectric ceramic composition, the high-temperature withstand voltage may be decreased due to a low sintering density. Furthermore, in a case in which the content is more than 5.0 mol, the high-temperature withstand voltage may be decreased due to formation of a secondary phase.

[0074] In a case in which the third accessory ingredient is provided in a ratio of 0.2 mol to 5.0 mol based on 100 mol of the base material powder, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, may be simultaneously provided.

[0075] In this case, the area ratio of the second crystal grain to the total area may also be 9.5% to 81.4%, as described below.

[0076] e) Fourth Accessory Ingredient

[0077] According to the exemplary embodiment, the dielectric ceramic composition may further contain an oxide or carbonate containing at least one of yttrium (Y), dysprosium (Dy), lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm) gadolinium (Gd) and erbium (Er), as a fourth accessory ingredient.

[0078] The fourth accessory ingredient may be provided in a ratio of 0.25 mol to 5.0 mol based on 100 mol of the base material powder.

[0079] Alternatively, the fourth accessory ingredient may be provided in the dielectric ceramic composition so that a sum of contents of one or more atoms selected among Y, Dy, Ho, La, Ce, Nd, Sm, Gd, and Er, contained in the fourth accessory ingredient is in a ratio of 0.5 at % to 10.0 at %.

[0080] According to the exemplary embodiment, the fourth accessory ingredient may serve to prevent deterioration of the reliability of the multilayer ceramic capacitor to which the dielectric ceramic composition is applied, and in a case in which the fourth accessory ingredient is provided in a ratio of 0.25 mol to 5.0 mol based on 100 mol of the base material powder, a dielectric ceramic composition capable of implementing high permittivity and having excellent high-temperature withstand voltage characteristics may be provided.

[0081] In a case in which the dielectric ceramic composition contains the fourth accessory ingredient, high-temperature withstand voltage characteristics may be improved as compared to a case in which the dielectric ceramic composition does not contain the fourth accessory ingredient. In a case in which the content of the fourth accessory ingredient is more than 5.0 mol based on 100 mol of the base material powder, the high-temperature withstand voltage may be decreased due to formation of a secondary phase.

[0082] In a case in which the fourth accessory ingredient is provided in a ratio of 0.25 mol to 5.0 mol based on 100 mol of the base material powder, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/pm or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, may be simultaneously implemented.

[0083] In this case, the area ratio of the second crystal grain to the total area may also be 9.5% to 81.4%, as described below.

[0084] f) Fifth Accessory Ingredient

[0085] According to the exemplary embodiment, the dielectric ceramic composition may contain one or more of an oxide and a carbonate of a fixed-valence acceptor element including Mg as a fifth accessory ingredient. For example, the fifth accessory ingredient may be MgCO.sub.3.

[0086] The fifth accessory ingredient may be provided in a ratio of 0.5 mol to 5.0 mol based on 100 mol of the base material powder.

[0087] In a case in which the dielectric ceramic composition contains MgCO.sub.3 as the fifth accessory ingredient, a room-temperature specific resistance value may be increased as compared to a case in which the dielectric ceramic composition does not contain MgCO.sub.3. In a case in which the content of the fifth accessory ingredient is more than 5.0 mol based on 100 mol of the base material powder, the high-temperature withstand voltage may be decreased due to formation of a secondary phase.

[0088] That is, in a case in which the fifth accessory ingredient is contained in a ratio of 0.5 mol to 5.0 mol based on 100 mol of the base material powder, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, may be simultaneously provided.

[0089] In this case, the area ratio of the second crystal grain to the total area may also be 9.5% to 81.4%, as described below.

[0090] FIG. 2 is a schematic perspective view illustrating a multilayer ceramic capacitor 100 according to an exemplary embodiment, and FIG. 3 is a schematic cross-sectional view illustrating the multilayer ceramic capacitor 100 taken along the line of FIG. 2.

[0091] Referring to FIGS. 2 and 3, the multilayer ceramic capacitor 100 according to an exemplary embodiment may include a ceramic body 110 in which dielectric layers 111 and first and second internal electrodes 121 and 122 are alternately stacked. First and second external electrodes 131 and 132 electrically connected to the first and second internal electrodes 121 and 122 alternately disposed in the ceramic body 110, respectively, may be formed on both end portions of the ceramic body 110.

[0092] A shape of the ceramic body 110 is not particularly limited, but generally may be a hexahedral shape. In addition, dimensions of the ceramic body 110 are not particularly limited, and the ceramic body 110 may have a suitable dimension depending on the use. For example, the ceramic body 110 may have dimensions of (0.65.6 mm)(0.35.0 mm)(0.31.9 mm).

[0093] A thickness of the dielectric layer 111 may be optionally changed according to a capacitance design of the capacitor. According to the exemplary embodiment, a thickness of a single dielectric layer after sintering may be preferably 0.1 m or more.

[0094] In a case in which the dielectric layer has an excessively low thickness, the number of crystal grains present in the single dielectric layer is small (e.g., the number of crystal grains in a thickness of the dielectric layer between two adjacent internal electrodes 121 and 122), which has a negative influence on reliability. Therefore, the thickness of the dielectric layer may be 0.1 m or more.

[0095] The first and second internal electrodes 121 and 122 may be stacked so that end surfaces thereof are alternately exposed to respective surfaces of both end portions of the ceramic body 110 opposing each other.

[0096] The first and second external electrodes 131 and 132 may be formed on respective end portions of the ceramic body 110 and respectively electrically connected to the exposed end surfaces of the first and second internal electrodes 121 and 122 that are alternately disposed, thereby configuring a capacitor circuit.

[0097] A conductive material contained in the first and second internal electrodes 121 and 122 is not particularly limited, but the dielectric layer 111 according to the exemplary embodiment may be formed using the dielectric ceramic composition according to the exemplary embodiment.

[0098] The dielectric ceramic composition according to the exemplary embodiment may contain the first main ingredient of BaTiO.sub.3 and the second main ingredient of BaTi.sub.2O.sub.5, wherein the base material powder containing the first and second main ingredients is represented by (1-x)BaTiO.sub.3-xBaTi.sub.2O.sub.5, and x satisfies 0.1x0.8.

[0099] A thickness of the first and second internal electrodes 121 and 122 may be appropriately determined depending on the intended application or use of the capacitor, but is not particularly limited. For example, the thickness of the first and second internal electrodes 121 and 122 may be 0.1 to 5 m or 0.1 to 2.5 m.

[0100] A conductive material contained in the first and second external electrodes 131 and 132 is not particularly limited, but Ni, Cu, or alloys thereof may be used.

[0101] A thickness of the first and second external electrodes 131 and 132 may be appropriately determined depending on the intended application or use, but is not particularly limited. For example, the thickness of the first and second external electrodes 131 and 132 may be 10 to 50 m.

[0102] Hereinafter, the capacitor and dielectric ceramic composition will be described in more detail through Inventive Examples and Comparative Examples, but these are merely to help in a specific understanding of the present disclosure. Therefore, the scope of the present disclosure is not limited to Inventive Examples.

[0103] After compositions containing ingredients illustrated in the following Tables 1, 3, and 5 were each mixed with a dispersant using ethanol and toluene as solvents, a binder was mixed with each of the mixtures, thereby manufacturing ceramic sheets.

[0104] As a main ingredient base material, BaTiO.sub.3 and BaTi.sub.2O.sub.5 powders having an average particle size of 300 nm were used.

[0105] An active sheet was manufactured by printing a Ni electrode on the formed ceramic sheet and stacking 21 ceramic sheets on which the Ni electrode was printed, and covers positioned on and below the active sheet were manufactured by stacking 25 cover sheets (10-13 m). Thereafter, the active sheet and the covers were compressed, thereby manufacturing a compressed bar.

[0106] Then, the compressed bar was cut into chips having a size of 3.2 mm1.6 mm using a cutter.

[0107] After the cut chip was calcined in order to remove the binder, the calcined chip was sintered at 1200 C. under a reduction atmosphere (1.0% of H2/99% of N.sub.2, H.sub.2O/H.sub.2/N.sub.2atmosphere), and external electrodes were formed on the sintered chip using a Cu paste.

[0108] Room-temperature capacitance and dissipation factors (DFs) of prototype multilayer ceramic capacitor (MLCC) samples completed as described above were measured at 1 kHz and AC 0.2V/m using an LCR-meter.

[0109] Permittivity of a dielectric material of the multilayer ceramic capacitor (MLCC) was calculated from the measured capacitance, a thickness of a dielectric layer, an area of internal electrodes, and the number of stacked dielectric layers of the multilayer ceramic capacitor.

[0110] Room-temperature insulation resistance (IR) was measured after 60 seconds in a state in which ten samples each were taken and DC 10V/m was applied thereto.

[0111] The temperature coefficient of capacitance (TCC) was measured in a temperature range from 55 to 200 C.

[0112] In a high-temperature IR boosting test, a resistance degradation behavior was measured while increasing a voltage step by 5V/m at 200 C., wherein the time of each step was 10 minutes and the resistance value was measured every 5 seconds.

[0113] A high-temperature withstand voltage was derived from the high-temperature IR boosting test. Here, the high-temperature withstand voltage means a voltage at which an IR withstands 105Q or more when the high-temperature withstand voltage is measured by applying a voltage step of DC 5V/m per a unit thickness of the dielectric layer at 200 C. for 10 minutes and continuously increasing the voltage step.

[0114] An RC value is a product of a room-temperature capacitance value measured at AC 0.2V/m and 1 kHz and an insulation resistance value measured at DC 10V/m.

[0115] Tables 2, 4, and 6 indicate characteristics of prototype multilayer ceramic capacitors (MLCCs) to which Ni internal electrodes corresponding to compositions illustrated in Tables 1, 3, and 5 were applied.

[0116] Inventive Examples 1 to 12 shown in Table 1 are Inventive Examples having different values of x when a content of a first accessory ingredient (MnO.sub.2) is 0.5 mol, a content of a second accessory ingredient (BaCO.sub.3) is 1.0 mol, and a content of a third accessory ingredient (SiO.sub.2) is 1.0 mol based on 100 mol of a base material powder ((1-x) BaTiO.sub.3-xBaTi.sub.2O.sub.5). Table 2 reports characteristics of prototype multilayer ceramic capacitors (MLCCs) including dielectric layers manufactured using the dielectric ceramic compositions of Inventive Examples 1 to 12 in Table 1, having Ni internal electrodes, and having been sintered under a reduction atmosphere.

[0117] In cases (Inventive Examples 1 and 2) in which a composition ratio x of BaTi.sub.2O.sub.5 was less than 0.05, high-temperature (150 C.) TCC exceeded 15%, and in cases (Inventive Examples 11 and 12) in which the composition ratio x of BaTi.sub.2O.sub.5 was excessively high (0.9 or more), room-temperature specific resistance was decreased to be less than 1E11 Ohm-cm and a high-temperature (200 C.) withstand voltage was decreased to be less than 50V/m.

[0118] In cases (Inventive Examples 3 to 10) in which the composition ratio x of BaTi.sub.2O.sub.5 was in a range of 0.1 to 0.8, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, were simultaneously provided.

[0119] In a case of manufacturing the dielectric layer by sintering the dielectric ceramic composition according to the exemplary embodiment at 1200 C. under a reduction atmosphere (1.0% of H2/99% of N.sub.2, H.sub.2O/H.sub.2/N.sub.2 atmosphere) or manufacturing the multilayer ceramic capacitor by printing the Ni internal electrode on the dielectric layer, a microstructure of dielectric layer may include a first crystal grain and a second crystal grain.

[0120] Contents of Ba and Ta at a total of four points, P1 to P4 in a single crystal grain were analyzed using scanning transmission electron microscopy (STEM)/wavelength dispersive X-ray spectroscopy (WDS) or STEM/electron energy loss spectroscopy (EELS).

[0121] As a result of calculating average values of the contents of Ba and Ti at the four points, the first crystal grain was defined as a crystal grain satisfying Ti/Ba content ratio<1.5 and the second crystal grain was defined as a crystal grain satisfying 1.5content ratio2.5.

[0122] Referring to Inventive Examples 1 to 12 in Table 1, it may be appreciated that in order to achieve the desired characteristics, the dielectric layer of the multilayer ceramic capacitor includes the first and second crystal grains, and an area ratio of the second crystal grain to a total area is 9.5% to 81.4%.

[0123] That is, in a case in which an area ratio of a second crystal grain per unit area is 9.5% to 81.4% at the time of observing a microstructure of a dielectric layer of a multilayer ceramic capacitor, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, may be simultaneously provided.

[0124] Inventive Examples 13 to 20 shown in Table 3 are Inventive Examples in which content of a first accessory ingredient (MnO.sub.2) is varied when a content of a second accessory ingredient (BaCO.sub.3) was 1.0 mol and a content of a third accessory ingredient (SiO.sub.2) was 1.0 mol based on 100 mol of a base material powder (0.5BaTiO.sub.3-0.5BaTi.sub.2O.sub.5) Table 4 reports characteristics of prototype multilayer ceramic capacitors (MLCCs) including dielectric layers manufactured using the dielectric ceramic compositions of Inventive

[0125] Examples 13 to 20 in Table 3, having Ni internal electrodes, and having been sintered under a reduction atmosphere.

[0126] In a case (Inventive Example 13) in which the first accessory ingredient (MnO.sub.2) was not added, a high-temperature withstand voltage was decreased to be less than 50V/m. Further, in a case (Inventive Example 20) in which the content of the added first accessory ingredient (MnO.sub.2) was excessively high (e.g., 8 mol based on 100 mol of the base material powder), the high-temperature withstand voltage was also decreased to be less than 50V/m.

[0127] That is, in cases (Inventive Examples 14 to 19) in which the content of the first accessory ingredient (MnO.sub.2) was 0.2 mol to 5.0 mol based on 100 mol of the base material powder, the multilayer ceramic capacitor exhibited excellent characteristics including the high-temperature (200 C.) withstand voltage of 50V/m or more.

[0128] Inventive Examples 21 to 23 in Table 3 are Inventive Examples in which the dielectric ceramic composition contained both MnO.sub.2 and V.sub.2O.sub.5 as the first accessory ingredient, and Table 4 reports characteristics of prototype multilayer ceramic capacitors (MLCCs) including dielectric layers manufactured using the dielectric ceramic compositions of Inventive Examples 21 to 23 of Table 3, having Ni internal electrodes, and having been sintered under a reduction atmosphere.

[0129] It may be appreciated that even though the dielectric ceramic composition contained only MnO.sub.2 as the first accessory ingredient (Inventive Examples 15 and 19), or contained both MnO.sub.2 and V.sub.2O.sub.5 as the first accessory ingredient (Inventive Examples 21 and 22), when a sum of contents (at %) of Mn and V atoms contained as the first accessory ingredient was the same, similar characteristics were provided.

[0130] That is, it may be appreciated that in a case (Inventive Example 15) in which only Mn was contained at a content of 0.5 at % and a case (Inventive Example 21) in which both Mn and V were contained and a sum of contents of Mn and V was 0.5 at % (Mn: 0.25 at %, V: 0.25 at %), characteristics were similar to each other.

[0131] Further, it may be appreciated that in a case (Inventive Example 19) in which only Mn was contained at a content of 5.0 at % and a case (Inventive Example 22) in which both Mn and V were contained and a sum of the contents of Mn and V was 5.0 at % (Mn: 2.5 at %, V: 2.5 at %), characteristics were similar to each other.

[0132] In cases (Inventive Examples 14 to 19, 21, and 22) in which a total content (based on at %) of variable valence acceptors contained as the first accessory ingredient was 0.2 to 5.0 at %, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, were simultaneously provided.

[0133] It may be appreciated that in this case, the area ratio of the second crystal grain to the total area was also in a range of 9.5% to 81.4%.

[0134] Inventive Examples 24 to 32 in Table 3 are Inventive Examples in which content of the second accessory ingredient (BaCO.sub.3) is varied while the content of the first accessory ingredient (MnO.sub.2) is 0.5 mol and the content of the third accessory ingredient (SiO.sub.2) is 1.0 mol based on 100 mol of the base material powder (0.5BaTiO.sub.3-0.5BaTi.sub.2O.sub.5). Table 4 reports characteristics of prototype multilayer ceramic capacitors (MLCCs) including dielectric layers manufactured using the dielectric ceramic compositions of Inventive Examples 24 to 32, having Ni internal electrodes, and having been sintered under a reduction atmosphere.

[0135] In a case (Inventive Example 24) in which the second accessory ingredient (BaCO.sub.3) was not added or a case (Inventive Example 32) in which the content of the added second accessory ingredient (BaCO.sub.3) was excessively high (15 mol or so) based on 100 mol of the base material powder, a sintering density was low, such that high-temperature withstand voltage was decreased to be less than 50V/m.

[0136] However, in cases (Inventive Examples 25 to 31) in which the content of the second accessory ingredient (BaCO.sub.3) was 0.2 mol to 10 mol based on 100 mol of the base material powder, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, were simultaneously provided.

[0137] It may be appreciated that in this case, the area ratio of the second crystal grain to the total area was also in a range of 9.5% to 81.4%.

[0138] Inventive Examples 33 to 39 shown in Table 3 are Inventive Examples in which content of the third accessory ingredient (SiO.sub.2) is varied when the content of the first accessory ingredient (MnO.sub.2) is 0.5 mol and the content of the second accessory ingredient (BaCO.sub.3) is 1.0 mol based on 100 mol of the base material powder (0.5BaTiO.sub.3-0.5BaTi.sub.2O.sub.5). Table 4 reports characteristics of prototype multilayer ceramic capacitors (MLCCs) including dielectric layers manufactured using the dielectric ceramic compositions of Inventive Examples 33 to 39, having Ni internal electrodes, and having been sintered under a reduction atmosphere.

[0139] In cases (Inventive Examples 33 and 34) in which the content of the third accessory ingredient (SiO.sub.2) was 0.1 mol or less based on 100 mol of the base material powder, the sintering density was low, such that the high-temperature withstand voltage was decreased to be less than 50V/m. Furthermore, in a case (Inventive Example 39) in which the content of the added third accessory ingredient (SiO.sub.2) was excessively high (7.0 mol or so) based on 100 mol of the base material powder, the high-temperature withstand voltage was decreased to be less than 50V/m due to formation of a secondary phase, and the like.

[0140] However, in cases (Inventive Examples 35 to 38) in which the content of the third accessory ingredient (SiO.sub.2) was 0.2 mol to 5.0 mol based on 100 mol of the base material powder, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, were simultaneously provided.

[0141] It may be appreciated that in this case, the area ratio of the second crystal grain to the total area was also in a range of 9.5% to 81.4%.

[0142] Inventive Examples 40 to 46 shown in Table 5 are Inventive Examples in which content of a fourth accessory ingredient (Y.sub.2O.sub.3) was varied when the content of the first accessory ingredient (MnO.sub.2) was 0.5 mol, the content of the second accessory ingredient (BaCO.sub.3) was 1.0 mol, and the content of the third accessory ingredient (SiO.sub.2) was 1.0 mol based on 100 mol of the base material powder (0.5BaTiO.sub.3-0.5BaTi.sub.2O.sub.5). Table 6 reports characteristics of prototype multilayer ceramic capacitors (MLCCs) including dielectric layers manufactured using the dielectric ceramic compositions of Inventive Examples 40 to 46, having Ni internal electrodes, and having been sintered under a reduction atmosphere.

[0143] It may be appreciated that when Y.sub.2O.sub.3 was added as the fourth accessory ingredient, high-temperature withstand voltage characteristics were improved as compared to a case (Inventive Example 7) in which the fourth accessory ingredient (Y.sub.2O.sub.3) was not added. However, in a case (Inventive Example 46) in which the content of the added fourth accessory ingredient (Y.sub.2O.sub.3) was excessively high (7 mol) based on 100 mol of the base material powder, the high-temperature withstand voltage was decreased to be less than 50V/m due to formation of a secondary phase.

[0144] Inventive Examples 47 to 49 in Table 5 are Inventive Examples in which a content of a fourth accessory ingredient (Dy.sub.2O.sub.3) is varied when the content of the first accessory ingredient (MnO.sub.2) is 0.5 mol, the content of the second accessory ingredient (BaCO.sub.3) is 1.0 mol, and the content of the third accessory ingredient (SiO.sub.2) is 1.0 mol based on 100 mol of the base material powder (0.5BaTiO.sub.3-0.5BaTi.sub.2O.sub.5). Table 6 reports characteristics of prototype multilayer ceramic capacitors (MLCCs) including dielectric layers manufactured using the dielectric ceramic compositions of Inventive Examples 47 to 49, having Ni internal electrodes, and having been sintered under a reduction atmosphere.

[0145] Comparing Inventive Examples 42 and 47, Inventive Examples 45 and 48, and Inventive Examples 46 and 49 with each other, it may be appreciated that when the contents of rare earth elements contained in the fourth accessory ingredient were equal to each other based on at %, similar characteristics were provided regardless of the kind of rare earth element.

[0146] That is, in cases (Inventive Examples 40 to 45, 47, and 48) in which the content of the fourth accessory ingredient was 0.25 mol to 5.0 mol based on 100 mol of the base material powder or the content (based on at %) of the rare earth element of the fourth accessory ingredient was 0.5 at % to 10 at %, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, were simultaneously provided.

[0147] It may be appreciated that in this case, the area ratio of the second crystal grain to the total area was also in a range of 9.5% to 81.4%.

[0148] Inventive Examples 50 to 55 in Table 5 are Inventive Examples in which a content of a fifth accessory ingredient (MgCO.sub.3) is varied when the content of the first accessory ingredient (MnO.sub.2) is 0.5 mol, the content of the second accessory ingredient (BaCO.sub.3) is 1.0 mol, the content of the third accessory ingredient (SiO.sub.2) is 1.0 mol, and the content of the fourth accessory ingredient (Y.sub.2O.sub.3) is 2.0 mol based on 100 mol of the base material powder (0.5BaTiO.sub.3-0.5BaTi.sub.2O.sub.5). Table 6 reports characteristics of prototype multilayer ceramic capacitors (MLCCs) including dielectric layers manufactured using the dielectric ceramic compositions of Inventive

[0149] Examples 50 to 55, having Ni internal electrodes, and having been sintered under a reduction atmosphere.

[0150] In cases in which the fifth accessory ingredient (MgCO.sub.3) was added, a room-temperature specific resistance value was increased as compared to the case (inventive Example 7) in which the fifth accessory ingredient (MgCO.sub.3) was not added. However, in a case (Inventive Example 55) in which the content of the added fifth accessory ingredient (MgCO.sub.3) was excessively high (7 mol or so) based on 100 mol of the base material powder, the high-temperature withstand voltage was decreased to be less than 50V/m due to formation of a secondary phase, and the like.

[0151] That is, in cases (Inventive Examples 50 to 54) in which the content of the fifth accessory ingredient (MgCO.sub.3) was 0.5 mol to 5.0 mol based on 100 mol of the base material powder, all of the desired characteristics, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 150 C.) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, were simultaneously provided.

[0152] It may be appreciated that in this case, the area ratio of the second crystal grain to the total area was also in a range of 9.5% to 81.4%.

[0153] As set forth above, with the dielectric ceramic composition, the multilayer ceramic capacitor containing the same, and the method for manufacturing a multilayer ceramic capacitor according to exemplary embodiments, all of the desired characteristics of the present disclosure, that is room-temperature specific resistance of 1E11 Ohm-cm or more, high-temperature (200 C.) withstand voltage of 50V/m or more, TCC (at 1500) less than 15%, TCC (at 200 C.) less than 22%, and room-temperature permittivity of 150 or more, can be simultaneously provided.

[0154] While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present invention as defined by the appended claims.