Multilayer Ceramic Capacitors

Abstract

The present invention provides a multilayer ceramic capacitor which is provided with an internal electrode that is capable of maintaining the coverage relatively high even if formed into a thin layer.　According to the present invention, a multilayer ceramic capacitor (1) is provided with a multilayer body (2) which comprises a plurality of stacked dielectric layers (3) that are formed of a ceramic, and a plurality of internal electrodes (4, 5) that are respectively arranged along a plurality of interfaces between the dielectric layers (3). With respect to this multilayer ceramic capacitor (1), the internal electrodes (4, 5) contain at least one substance that is selected from among NiTiO3, MgTiO3 and MnTiO3 in addition to a conductive metal component. It is preferable that the internal electrodes (4, 5) contain nickel as the conductive metal component.

Description

[Technical field]

[0001] The present invention relates to a multilayer ceramic capacitor, and more particularly to the composition of internal electrodes provided in the multilayer ceramic capacitor. [Background technology]

[0002] A multilayer ceramic capacitor generally comprises a laminate having a plurality of laminated dielectric layers made of ceramic and a plurality of internal electrodes respectively arranged along a plurality of interfaces between the dielectric layers, and a plurality of external electrodes provided on the outer surface of the laminate and electrically connected to the internal electrodes. The internal electrodes comprise a plurality of first internal electrodes and a plurality of second internal electrodes alternately arranged in the stacking direction of the laminate, and the external electrodes comprise a first external electrode electrically connected to the first internal electrodes and a second external electrode electrically connected to the second internal electrodes.

[0003] In order to miniaturize and increase the capacity of a multilayer ceramic capacitor with such a structure, it is necessary to thin the dielectric layers and internal electrodes and to increase the coverage (electrode continuity) of the internal electrodes. Generally, in the firing process for manufacturing a multilayer ceramic capacitor, the temperature at which the conductive metal particles contained in the conductive paste film that will become the internal electrodes sinter is lower than the temperature at which the ceramic that constitutes the dielectric layers sinters, so the metal particles contained in the internal electrodes sinter first. This causes a decrease in the coverage of the internal electrodes. In particular, in the case of an internal electrode that is thinned to a thickness of 1 μm or less, the coverage is easily decreased, and this decrease in coverage is likely to hinder an increase in capacity.

[0004] Therefore, in order to form a thin internal electrode with high coverage, it is necessary to increase the temperature at which the conductive metal particles contained in the conductive paste film that will become the internal electrode are sintered in the firing process during the manufacture of the multilayer ceramic capacitor. This allows the temperature at which the metal particles contained in the conductive paste film that will become the internal electrode are sintered to be closer to the temperature at which the ceramic that constitutes the dielectric layer begins to sinter, and the timing of contraction during sintering between the internal electrode and the dielectric layer can be brought closer. As a result, the coverage of the internal electrode is increased, and a large capacity can be achieved.

[0005] In order to increase the coverage of the internal electrodes and realize a large capacity by the above-mentioned method, it is known to add a ceramic material having a composition similar to that of the ceramic constituting the dielectric layer, that is, a co-material, to the conductive paste for forming the internal electrodes, as described in, for example, paragraph 0004 of Patent Document 1 (JP Patent Publication No. 2016-31807). By adding the co-material, the sintering timing of the metal particles contained in the conductive paste film to become the internal electrodes can be shifted to a higher temperature, and the temperature at which the metal particles contained in the conductive paste film are sintered can be brought closer to the temperature at which the ceramic constituting the dielectric layer is sintered. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2016-31807 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, even if a co-material is added to the conductive paste for forming the internal electrodes, it cannot be denied that the temperature at which the metal particles contained in the conductive paste sinter is still lower than the temperature at which the ceramic that constitutes the dielectric layer sinters, and further improvement is desired. In particular, for internal electrodes that are thinned, for example to a thickness of 1 μm or less, there is a strong demand for an effective solution to the problem of reduced coverage that inhibits increased capacity.

[0008] The present invention has been made in view of the above-mentioned problems, and has an object to provide a multilayer ceramic capacitor having internal electrodes which can maintain a relatively high coverage even when the layers are made thin. [Means for solving the problem]

[0009] A multilayer ceramic capacitor according to the present invention includes a laminate having a plurality of laminated dielectric layers made of ceramic, and a plurality of internal electrodes respectively disposed along a plurality of interfaces between the dielectric layers.

[0010] In order to solve the above technical problems, in this invention, the internal electrode is made of NiTi O 3 oh and MnTiO3. Effect of the Invention

[0011] According to the present invention, the NiTi contained in the internal electrode O 3 oh At least one selected from the group consisting of MnTiO3 and MnTiO3 contributes to increasing the coverage of the internal electrodes. Therefore, even if the internal electrodes are made thinner, the coverage of the internal electrodes is not reduced, and it is possible to prevent the increase in capacitance of the multilayer ceramic capacitor from being hindered. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view that typically illustrates a multilayer ceramic capacitor 1 according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The structure of a multilayer ceramic capacitor 1 according to one embodiment of the present invention will be described with reference to FIG.

[0014] The multilayer ceramic capacitor 1 includes a laminate 2. The laminate 2 includes a plurality of laminated dielectric layers 3 made of ceramic, and a plurality of internal electrodes 4 and 5 arranged along the interfaces between the plurality of dielectric layers 3. The internal electrodes 4 and 5 are classified into a plurality of first internal electrodes 4 and a plurality of second internal electrodes 5 arranged alternately in the lamination direction of the laminate 3. A first external electrode 6 and a second external electrode 7 are provided on the outer surface of the laminate 2, more specifically, on each of the opposing end faces. The first external electrode 6 is electrically connected to the first internal electrode 4, and the second external electrode 7 is electrically connected to the second internal electrode 5.

[0015] The dielectric layer 3 is made of a ceramic mainly composed of ABO3 (A is at least one of Ba, Ca and Sr, and B is at least one of Ti and Zr). The ceramic mainly composed of ABO3 may further contain at least one of Mn, Mg, Si, Y, Dy and Gd as a secondary component.

[0016] The internal electrodes 4 and 5 preferably contain Ni as a conductive component. Furthermore, the internal electrodes 4 and 5 have a characteristic composition of NiTi O 3 oh and MnTiO3. O 3 oh and MnTiO3 have the ilmenite crystal structure.

[0017] As will be understood from the experimental examples described later, in a preferred embodiment, the dielectric layer 3 is made of a ceramic containing at least one selected from BaTiO3, SrTiO3, and CaZrO3 as a main component, and the internal electrodes 4 and 5 contain nickel as a conductive component and are made of a ceramic material such as NiTi O 3 oh and MnTiO3, and, if necessary, further contains at least one selected from BaTiO3, SrTiO3 and CaZrO3 contained in the dielectric layer 3.

[0018] The external electrodes 6 and 7 are formed, for example, by applying a conductive paste containing Ag or Cu as a main conductive component to the end faces of the laminate 2 and baking the paste. If necessary, for example, Ni plating and Sn plating may be applied on the thick film formed by baking.

[0019] The multilayer ceramic capacitor 1 is manufactured, for example, through the following steps. First, a ceramic slurry containing ceramic raw material powder having the above-mentioned composition is prepared. Next, a suitable sheet forming method is applied to the ceramic slurry to form ceramic green sheets. Next, a conductive paste to be each of the internal electrodes 4 and 5 is applied by printing or the like onto a predetermined ceramic green sheet among the plurality of ceramic green sheets. Next, the plurality of ceramic green sheets are stacked and then pressed together to obtain a green laminate. Next, the green laminate is fired. In this firing step, the ceramic green sheets become the dielectric layers 3. After that, the external electrodes 6 and 7 are formed on the end faces of the laminate 3.

[0020] The conductive paste to become the internal electrodes 4 and 5 used in manufacturing the multilayer ceramic capacitor 1 described above is preferably prepared as follows.

[0021] The conductive paste is produced by carrying out a first step of preparing a ceramic powder slurry containing a ceramic powder, an organic solvent and a dispersant, a second step of preparing a metal powder slurry containing a conductive metal powder, an organic solvent and a dispersant, a third step of preparing an organic vehicle containing an organic resin component and an organic solvent, and a fourth step of mixing the ceramic powder slurry, the metal powder slurry and the organic vehicle.

[0022] More specifically, in the first step, a ceramic powder slurry is prepared by mixing a ceramic powder and a dispersant in an organic solvent.

[0023] The ceramic powder may be, for example, NiTi as ABO3 oxide. O 3 oh and MnTiO3, and in addition thereto, at least one selected from BaTiO3, SrTiO3 and CaZrO3 may be used as a co-material.

[0024] When the conductive metal powder contained in the metal powder slurry produced in the second step described later contains nickel, NiTi as the above-mentioned ABO3 oxide is O 3 oh and MnTiO3 are ABO3 type oxides with a specific ionic radius, in which the ratio of the ionic radius of the A-site element in ABO3 in 6-coordination to the ionic radius of nickel in 6-coordination is 0.97 or more and 1.04 or less.

[0025] NiTi as ABO3 oxide O 3 ohThe ceramic powder consisting of at least one selected from MnTiO3 and MnTiO3 can suppress the reaction that may occur between the conductive metal powder contained in the metal powder slurry produced in the second step during firing. The ceramic powder contains the ABO3 oxide as the main component, and may further contain at least one of Mn, Mg, Si, Y, Dy, and Gd as a subcomponent. When such a subcomponent is contained, the grain growth of the ceramic particles is suppressed, and the sintering of the metal particles may be effectively suppressed.

[0026] As the dispersant mixed with the ceramic powder in the first step, for example, an anionic polymer dispersant can be used, and as the organic solvent, for example, dihydroterpineol can be used.

[0027] In the second step, a metal powder slurry is prepared by mixing the conductive metal powder and the dispersant with an organic solvent. The conductive metal powder may be, for example, a powder made of nickel or an alloy thereof. The dispersant and organic solvent used in the second step may be the same as those used in the first step.

[0028] In the third step, an organic vehicle is prepared by mixing an organic resin component with an organic solvent. For example, an ethyl cellulose resin can be used as the organic resin component. The organic solvent used in the third step can be the same as that used in the first step.

[0029] In the fourth step, the above-mentioned ceramic powder slurry, metal powder slurry, and organic vehicle are mixed together to obtain a conductive paste that will become the internal electrodes 4 and 5. This conductive paste contains a ceramic powder slurry, which, as described above, is NiTi as an ABO3 oxide with a specific ionic radius. O 3 ohand MnTiO3. Therefore, the internal electrodes 4 and 5 of the multilayer ceramic capacitor 1 manufactured through the firing process are made of at least one ceramic powder selected from NiTi O 3 oh and MnTiO3.

[0030] [Experimental Example] Next, an example of an experiment carried out to confirm the effects of the present invention will be described. In the experimental example, the ABO 3 One of the oxides is MgTiO 3 However, MgTiO 3 are excluded from the scope of this invention.

[0031] In this experimental example, nickel powder was prepared as the conductive metal powder contained in the conductive paste for forming internal electrodes.

[0032] On the other hand, in addition to NiTiO3, MgTiO3, and MnTiO3, CuTiO3, BaTiO3, CaZrO3, and SrTiO3 were prepared as ABO3 oxides with specific ionic radii that constitute the ceramic powder contained in the conductive paste for forming the internal electrodes. Table 1 shows the "crystal structure," "coordination number," "A-site element," and "ionic radius" for these ABO3 oxides. Note that Ba, Ca, and Sr have 12-coordination in the original perovskite structure, but when Ba, Ca, and Sr are dissolved in the site of the 6-coordination elements (Ni, Mg, Mn) of the ilmenite structure, they also have 6-coordination, so the "ionic radius" in Table 1 shows the value for 6-coordination.

[0033] [Table 1]

[0034] Below, experimental examples 1, 2, and 3 will be described, which were carried out by changing the ceramic raw material constituting the dielectric layer.

[0035] (Experimental Example 1) Main component of the ceramic that makes up the dielectric layer: BaTiO3 1. Preparation of BaTiO3-based ceramic raw material for the dielectric layer As starting materials, powders of BaCO3 and TiO2 as main components were weighed, mixed in a ball mill for 72 hours, and then heat-treated at a top temperature of 1000°C for 2 hours to obtain heat-treated powder. On the other hand, powders of MnO, Dy2O3, MgO, SiO2, and BaCO3 were prepared as subcomponents, and the subcomponent powders were weighed so that the composition ratio of the above heat-treated powder was 100BaTiO3+0.5Mn+1.0Dy+1.0Mg+1.0Si+2.0Ba. These subcomponent powders were added to the above heat-treated powder, mixed in a ball mill for 24 hours, and then dried to obtain BaTiO3-based ceramic raw material powder.

[0036] 2. Preparation of conductive paste for forming internal electrodes The "ABO3 oxide" powder shown in Table 2 below and the BaTiO3-based ceramic raw material powder for the dielectric layers were used as the ceramic powder contained in the conductive paste for forming the internal electrodes.

[0037] These "ABO3 oxide" powders and BaTiO3-based ceramic raw material powders were weighed out to obtain the "addition ratio" shown in Table 2. These powders were premixed with dihydroterpineol as an organic solvent and an anionic polymer dispersant as a dispersant in a media-free agitation mill, and then dispersed in a media agitation mill to produce a ceramic powder slurry (Step 1).

[0038] On the other hand, nickel powder as a conductive metal powder, dihydroterpineol as an organic solvent, and an anionic polymer dispersant as a dispersant were dispersed in a three-roll mill to prepare a metal powder slurry (second process).

[0039] Furthermore, an ethyl cellulose resin as an organic resin component and dihydroterpineol as an organic solvent were mixed together to obtain an organic vehicle (third step).

[0040] Thereafter, the metal powder slurry and the ceramic powder slurry were added to the organic vehicle and mixed and dispersed to prepare a conductive paste for forming internal electrodes (fourth step).

[0041] Table 2 shows the ratio of the ionic radius of the A-site element in 6-coordination to the ionic radius of nickel in 6-coordination to be included in the internal electrode, i.e., the "ionic radius ratio (A-site element / metallic nickel)." For sample 8, the ratio of the ionic radius of Ba in 6-coordination (1.35 Å) shown in Table 1 to the ionic radius of Ni in 6-coordination (0.69 Å) is shown.

[0042] 3. Fabrication of Multilayer Ceramic Capacitors A ceramic slurry containing the BaTiO3-based ceramic raw material powder prepared in 1 above was prepared, and then the ceramic slurry was subjected to a doctor blade method to form ceramic green sheets. Next, the conductive paste for forming internal electrodes prepared in 2 above was applied by screen printing onto a predetermined ceramic green sheet among the plurality of ceramic green sheets. Next, the plurality of ceramic green sheets were stacked and then pressed together to obtain a green laminate. Next, the green laminate was fired. After that, external electrodes were formed on the end faces of the sintered laminate to produce a sample multilayer ceramic capacitor.

[0043] 4. Evaluation

[0044] [Table 2]

[0045] An internal electrode and a dielectric layer located at the center in the height direction of a laminate included in a sample multilayer ceramic capacitor were peeled off from each other by electrochemical peeling.

[0046] Next, the center of the exposed internal electrode (1 / 2 in the width direction and 1 / 2 in the length direction) was observed using a microscope at 100x magnification. The obtained image was then analyzed to determine the percentage of the area of ​​the exposed portion that was occupied by the conductive film as the internal electrode, as the "coverage" shown in Table 2. "Coverage" of 80% or more was judged as good, with a "○" entered in the "Evaluation" column, and "Coverage" of less than 80% was judged as poor, with an "X" entered in the "Evaluation" column.

[0047] 5. Discussion In Table 2, samples 1 to 3 and 5 to 7 are rated as "○". In these samples 1 to 3 and 5 to 7, the internal electrodes contain NiTiO3, MgTiO3, or MnTiO3 as the ABO3 oxide. The internal electrodes also contain nickel as a conductive component.

[0048] Focusing on the ionic radius, first, the ionic radius of nickel in 6-coordination is 0.69 Å, as shown in the "NiTiO3" section of Table 1. On the other hand, the ionic radius of the A-site element in each of NiTiO3, MgTiO3, and MnTiO3 as the ABO3 oxides contained in the internal electrodes of samples 1 to 3 and 5 to 7 in 6-coordination is 0.69 Å, 0.72 Å, and 0.67 Å, ​​respectively, as shown in Table 1.

[0049] In samples 1 to 3 and 5 to 7 rated as "○", the ratio of the ionic radius of the A site element in ABO3 in 6-coordination to the ionic radius of the metal element contained in the conductive metal particle in 6-coordination, i.e., the "ionic radius ratio", was 0.97 or more and 1.04 or less.

[0050] In this way, NiTiO3, MgTiO3, and MnTiO3 as ABO3 oxides in samples 1 to 3 and 5 to 7 have an ionic radius of the A-site element in ABO3 in 6-coordination that is equal to or close to the ionic radius of nickel in 6-coordination as the conductive metal to be contained in the internal electrode, so that the energy difference with nickel in the internal electrode is 0 or small, and the oxides remain without being expelled from the internal electrode portion, thereby improving the heat resistance of the internal electrode. As a result, it is presumed that the coverage of samples 1 to 3 and 5 to 7 was high at 84% or more.

[0051] Also, as in samples 5 to 7, the addition ratio of NiTiO3, MgTiO3 and MnTiO3 is not necessarily 100%, and as long as it is 10% or more, the effect of improving coverage was confirmed compared to the case where none of NiTiO3, MgTiO3 and MnTiO3 is included. It is also noteworthy that in Experimental Example 1, the coverage of samples 5 to 7, in which the addition ratio of NiTiO3, MgTiO3 and MnTiO3 is 10%, shows the same value as the coverage of samples 1 to 3, in which the addition ratio is 100%.

[0052] In contrast, in sample 4, which was rated as "x", CuTiO3 was used as the ABO3 oxide, and the ionic radius of Cu, the A-site element in ABO3, in 6-coordination is 0.73 Å, as shown in Table 1. Therefore, the ratio of the ionic radius of Cu in 6-coordination to the ionic radius of nickel in 6-coordination, that is, the "ionic radius ratio", is 1.06. In other words, the "ionic radius ratio" was outside the range of 0.97 or more and 1.04 or less, and the coverage was low at 75%.

[0053] In addition, in sample 8, which was also evaluated as "x", only BaTiO3 as a co-material was added to the internal electrode. In this case, Ba, which is an element in the A site of the perovskite structure ABO3, has 12 coordination numbers, but when it dissolves in the A site of the ilmenite structure, it is necessary to compare the ionic radius at 6 coordination numbers, which is the coordination number of the A site of the ilmenite structure, and the ionic radius of Ba at 6 coordination numbers is 1.35 Å, as shown in Table 1. Therefore, the ratio of the ionic radius of Ba at 6 coordination numbers to the ionic radius of nickel at 6 coordination numbers, that is, the "ionic radius ratio", is 1.96. Therefore, the "ionic radius ratio" is outside the range of 0.97 to 1.04, and the coverage was low at 74%.

[0054] In samples 4 and 8, the "ionic radius ratio" was outside the range of 0.97 or more and 1.04 or less, and it is presumed that CuTiO3 and BaTiO3, respectively, were expelled from the internal electrode portion, the heat resistance of the internal electrode was not improved, and the coverage was reduced.

[0055] (Experimental Example 2) Main component of the ceramic that makes up the dielectric layer: CaZrO3 1. Preparation of CaZrO3-based ceramic raw material for the dielectric layer As starting materials, the main components CaCO3 and ZrO2 powders, and the sub-components MnO, SiO2 and MgO powders were weighed out and mixed in a ball mill for 72 hours, after which the mixture was heat-treated at a top temperature of 1000°C for 2 hours to obtain a CaZrO3-based ceramic raw material powder.

[0056] 2. Preparation of conductive paste for forming internal electrodes The "ABO3 oxide" powder shown in Table 3 below and the CaZrO3 ceramic raw material powder for the dielectric layers were used as the ceramic powder contained in the conductive paste for forming the internal electrodes.

[0057] These "ABO3 oxide" powders and CaZrO3-based ceramic raw material powders were weighed out to obtain the "addition ratio" shown in Table 3, and a conductive paste for forming internal electrodes was prepared through the same process as in Experimental Example 1 above.

[0058] Table 3 shows the "ionic radius ratio (A-site element / metallic nickel)" as in Table 2. For sample 18, the ratio of the ionic radius of Ca in 6-coordination (1.00 Å) shown in Table 1 to the ionic radius of Ni in 6-coordination (0.69 Å) is shown.

[0059] 3. Fabrication of Multilayer Ceramic Capacitors A ceramic slurry containing the CaZrO3-based ceramic raw material powder prepared in 1 above was prepared, and then the ceramic slurry was formed into ceramic green sheets by applying a doctor blade method. After that, a multilayer ceramic capacitor sample was prepared through the same steps as in Experimental Example 1.

[0060] 4. Evaluation

[0061] [Table 3]

[0062] According to the same procedure as in Experimental Example 1, the "coverage" was determined as shown in Table 3, and was similarly evaluated.

[0063] 5. Discussion In Table 3, samples 11 to 13 and 15 to 17 are rated as "○". In these samples 11 to 13 and 15 to 17, the internal electrodes contain NiTiO3, MgTiO3, or MnTiO3 as the ABO3 oxide. The internal electrodes also contain nickel as a conductive component.

[0064] Here, looking at the ionic radius, first, the ionic radius of nickel in 6-coordination is 0.69 Å, as shown in the "NiTiO3" section of Table 1. On the other hand, the ionic radius of the A-site element in each of NiTiO3, MgTiO3, and MnTiO3 as the ABO3 oxides contained in the internal electrodes of samples 11 to 13 and 15 to 17 in 6-coordination is 0.69 Å, 0.72 Å, and 0.67 Å, ​​respectively, as shown in Table 1.

[0065] In samples 11 to 13 and 15 to 17 rated as "○", the ratio of the ionic radius of the A site element in ABO3 in 6-coordination to the ionic radius of the metal element contained in the conductive metal particle in 6-coordination, i.e., the "ionic radius ratio", was 0.97 or more and 1.04 or less.

[0066] In this way, the ionic radius of the A-site element in ABO3, NiTiO3, MgTiO3, and MnTiO3 in samples 11 to 13 and 15 to 17, in 6-fold coordination, is equal to or close to the ionic radius of nickel in 6-fold coordination as the conductive metal to be contained in the internal electrode, and therefore the energy difference with the nickel in the internal electrode is zero or small, and so the oxides remain without being expelled from the internal electrode portion, thereby acting to improve the heat resistance of the internal electrode. As a result, it is presumed that the coverage was high at 81% or more in samples 11 to 13 and 15 to 17.

[0067] Also, like samples 15 to 17, the addition ratio of NiTiO3, MgTiO3 and MnTiO3 is not necessarily 100%, and if it is 10% or more, an effect of improving coverage was observed compared to the case where none of NiTiO3, MgTiO3 and MnTiO3 was included.

[0068] In contrast, in sample 14, which was rated as "x", CuTiO3 was used as the ABO3 oxide, and the ionic radius of Cu, the A-site element in ABO3, in 6-coordination is 0.73 Å, as shown in Table 1. Therefore, the ratio of the ionic radius of Cu in 6-coordination to the ionic radius of nickel in 6-coordination, that is, the "ionic radius ratio", is 1.06. In other words, the "ionic radius ratio" was outside the range of 0.97 or more and 1.04 or less, and the coverage was low at 75%.

[0069] In addition, in sample 18, which was also evaluated as "x", only CaZrO3 as a co-material was added to the internal electrode. In this case, Ca, which is the A-site element in ABO3 of the perovskite structure, has 12 coordination numbers, but when it dissolves in the A-site of the ilmenite structure, it is necessary to compare the ionic radius at 6 coordination numbers, which is the coordination number of the A-site of the ilmenite structure, and the ionic radius of Ca at 6 coordination numbers is 1.00 Å, as shown in Table 1. Therefore, the ratio of the ionic radius of Ca at 6 coordination numbers to the ionic radius of nickel at 6 coordination numbers, that is, the "ionic radius ratio", is 1.45. Therefore, the "ionic radius ratio" is outside the range of 0.97 to 1.04, and the coverage was low at 72%.

[0070] In these samples 14 and 18, the "ionic radius ratio" was outside the range of 0.97 or more and 1.04 or less, and it is presumed that CuTiO3 and CaZrO3 were expelled from the internal electrode part, respectively, so that the heat resistance of the internal electrode was not improved and the coverage was reduced.

[0071] (Experimental Example 3) Main component of the ceramic that makes up the dielectric layer: SrTiO3 1. Preparation of SrTiO3-based ceramic raw material for the dielectric layer As starting materials, the main component powders of SrCO3 and TiO2, and the sub-components powders of MnO, SiO2 and MgO were weighed out and mixed in a ball mill for 72 hours, after which the mixture was heat-treated at a top temperature of 1000°C for 2 hours to obtain SrTiO3-based ceramic raw material powder.

[0072] 2. Preparation of conductive paste for forming internal electrodes The "ABO3 oxide" powder shown in Table 4 below and the SrTiO3 ceramic raw material powder for the dielectric layers were used as the ceramic powder contained in the conductive paste for forming the internal electrodes.

[0073] These "ABO3 oxide" powders and SrTiO3-based ceramic raw material powders were weighed out to obtain the "addition ratio" shown in Table 4, and a conductive paste for forming internal electrodes was prepared through the same process as in Experimental Example 1 above.

[0074] Table 4 shows the "ionic radius ratio (A-site element / metallic nickel)" as in Table 2. For sample 28, the ratio of the ionic radius of Sr in 6-coordination (1.18 Å) shown in Table 1 to the ionic radius of Ni in 6-coordination (0.69 Å) is shown.

[0075] 3. Fabrication of Multilayer Ceramic Capacitors A ceramic slurry containing the SrTiO3-based ceramic raw material powder prepared in 1 above was prepared, and then the ceramic slurry was formed into ceramic green sheets by applying a doctor blade method. After that, a multilayer ceramic capacitor sample was produced through the same steps as in Experimental Example 1.

[0076] 4. Evaluation

[0077] [Table 4]

[0078] Following the same procedure as in Experimental Example 1, the "coverage" was determined as shown in Table 4 and evaluated in the same manner.

[0079] 5. Discussion In Table 4, samples 21 to 23 and 25 to 27 are rated as "○". In these samples 21 to 23 and 25 to 27, the internal electrodes contain NiTiO3, MgTiO3, or MnTiO3 as the ABO3 oxide. The internal electrodes also contain nickel as a conductive component.

[0080] Here, looking at the ionic radius, first, the ionic radius of nickel in 6-coordination is 0.69 Å, as shown in the "NiTiO3" section of Table 1. On the other hand, the ionic radius of the A-site element in each of NiTiO3, MgTiO3, and MnTiO3 as the ABO3 oxides contained in the internal electrodes of samples 21 to 23 and 25 to 27 in 6-coordination is 0.69 Å, 0.72 Å, and 0.67 Å, ​​respectively, as shown in Table 1.

[0081] In samples 21 to 23 and 25 to 27 rated as "○", the ratio of the ionic radius of the A site element in ABO3 in 6-coordination to the ionic radius of the metal element contained in the conductive metal particle in 6-coordination, i.e., the "ionic radius ratio", was 0.97 or more and 1.04 or less.

[0082] In this way, the ionic radius of the A-site element in ABO3, NiTiO3, MgTiO3 and MnTiO3 in samples 21 to 23 and 25 to 27, in 6-fold coordination, is equal to or close to the ionic radius of nickel in 6-fold coordination as the conductive metal to be contained in the internal electrode, and therefore the energy difference with the nickel in the internal electrode is zero or small, and so the oxides remain without being expelled from the internal electrode, thereby acting to improve the heat resistance of the internal electrode. As a result, it is presumed that the coverage was high at 80% or more in samples 21 to 23 and 25 to 27.

[0083] Also, like samples 25 to 27, the addition ratio of NiTiO3, MgTiO3 and MnTiO3 is not necessarily 100%, and if it is 10% or more, an effect of improving coverage was observed compared to the case where none of NiTiO3, MgTiO3 and MnTiO3 was included.

[0084] In contrast, in sample 24, which was rated as "x", CuTiO3 was used as the ABO3 oxide, and the ionic radius of Cu, the A-site element in ABO3, in 6-coordination is 0.73 Å, as shown in Table 1. Therefore, the ratio of the ionic radius of Cu in 6-coordination to the ionic radius of nickel in 6-coordination, that is, the "ionic radius ratio", is 1.06. In other words, the "ionic radius ratio" was outside the range of 0.97 or more and 1.04 or less, and the coverage was low at 72%.

[0085] In addition, in sample 28, which was also evaluated as "x", only SrTiO3 as a co-material was added to the internal electrode. In this case, Sr, which is an element in the A site of the perovskite structure ABO3, has 12 coordination numbers, but when it dissolves in the A site of the ilmenite structure, it is necessary to compare the ionic radius at 6 coordination numbers, which is the coordination number of the A site of the ilmenite structure, and the ionic radius of Sr at 6 coordination numbers is 1.18 Å, as shown in Table 1. Therefore, the ratio of the ionic radius of Sr at 6 coordination numbers to the ionic radius of nickel at 6 coordination numbers, that is, the "ionic radius ratio", is 1.71. Therefore, the "ionic radius ratio" is outside the range of 0.97 to 1.04, and the coverage was low at 70%.

[0086] In these samples 24 and 28, the "ionic radius ratio" was outside the range of 0.97 or more and 1.04 or less, and it is presumed that CuTiO3 and SrTiO3 were expelled from the internal electrode portion, respectively, resulting in no improvement in the heat resistance of the internal electrode and reduced coverage.

[0087] In the above-described experimental examples 1 to 3, nickel powder was used as the conductive metal powder contained in the conductive paste for forming the internal electrodes. In many cases, commercially available multilayer ceramic capacitors use nickel as the conductive component of the internal electrodes, so using nickel powder as the conductive metal powder contained in the conductive paste for forming the internal electrodes is advantageous in that it reduces design changes.

[0088] However, metals other than nickel may be used as the conductive metal contained in the internal electrodes as long as the ionic radius in 6-coordination of the conductive metal element contained in the internal electrodes satisfies the relationship that the ionic radius in 6-coordination of the A-site element in NiTiO3, MgTiO3, and MnTiO3 is greater than or equal to (1 / 1.04) and less than or equal to (1 / 0.97). [Explanation of symbols]

[0089] 1. Multilayer ceramic capacitors 2. Laminate 3 Dielectric Layer 4,5 Internal electrodes 6,7 External electrodes

Claims

1. A laminate having a plurality of laminated dielectric layers made of ceramic and a plurality of internal electrodes respectively disposed along a plurality of interfaces between the dielectric layers, The internal electrodes are made of NiTiO 3 and MnTiO ３ At least one selected from Multilayer ceramic capacitor.

2. 2. The multilayer ceramic capacitor according to claim 1, wherein the internal electrodes contain nickel as a conductive component.

3. 3. The multilayer ceramic capacitor according to claim 1, wherein the internal electrodes have a thickness of 1 μm or less.

4. 3. The multilayer ceramic capacitor according to claim 1, wherein the internal electrodes have a coverage of 80% or more.

5. The dielectric layer is BaTiO ３ , SrTiO ３ and CaZrO ３ The internal electrodes are made of ceramics mainly composed of at least one selected from the following: ３ , SrTiO ３ and CaZrO ３ The multilayer ceramic capacitor according to claim 1 or 2, further comprising at least one selected from the following:

Images