Conductive paste and multilayer ceramic capacitor

Abstract

Provided are a multilayer ceramic capacitor or the like having high continuity of an internal electrode layer.　The multilayer ceramic capacitor includes a laminate having a dielectric layer and an internal electrode layer which are alternately laminated, wherein: the dielectric layer includes crystal particles having a perovskite structure having an A site and a B site; the internal electrode layer includes a main component that is a metal composed of a metal element (1) and a sub-component containing a metal element (2); the metal element (2) includes a metal element (2-1), which is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements; and the total amount (parts by mol) of the metal element (2-1) is greater than the content (parts by mol) of each metal element other than the metal element (2-1) among the metal element (2), and is less than the content (parts by mol) of the metal element (1).

Description

Conductive Paste and Multilayer Ceramic Capacitor

[0001] The present disclosure relates to a conductive paste and a multilayer ceramic capacitor.

[0002] The multilayer ceramic capacitor includes a laminate having a plurality of dielectric layers and a plurality of internal electrode layers alternately laminated, and an external electrode located on the surface of the laminate and connected to the plurality of internal electrode layers. The multilayer ceramic capacitor is obtained by laminating and firing a plurality of sheets printed with a conductive paste for forming an internal electrode layer containing Ni or the like as a main component on the surface of a green sheet for a dielectric layer mainly composed of a dielectric such as barium titanate.

[0003] Generally, since the firing rate of the conductive paste for forming the internal electrode layer is faster than the firing rate of the green sheet for the dielectric layer, when firing at the firing temperature at which the dielectric is sintered, the internal electrode layer becomes over-sintered and the internal electrode continuity decreases. Therefore, conventionally, in order to slow down the firing rate of the conductive paste for forming the internal electrode layer and make it closer to the firing rate of the green sheet for the dielectric layer, a co-material having the same composition as the dielectric in the green sheet for the dielectric layer is blended into the conductive paste for forming the internal electrode layer. For example, Patent Document 1 describes manufacturing a multilayer ceramic capacitor using a green sheet for a dielectric layer containing barium titanate and a conductive paste for forming an internal electrode layer containing Ni as a main component and containing barium titanate as a co-material.

[0004] Also, Patent Document 2 describes manufacturing barium titanate powder by a hydrothermal synthesis method.

[0005] JP-A-2014-67775, JP-A-2014-152064

[0006] The multilayer ceramic capacitor disclosed herein comprises a laminate having alternately stacked dielectric layers and internal electrode layers, wherein the dielectric layers comprise crystalline particles having a perovskite structure with A sites and B sites, and the internal electrode layers comprise a main component which is a metal composed of a metal element (1) and a secondary component which comprises a metal element (2), wherein the metal element (2) comprises a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y and rare earth elements, and the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2-1) in the metal element (2-1), and less than the content (moles) of the metal element (1).

[0007] The hydrothermal synthesis method allows for the production of fine barium titanate with a sharp particle size distribution. Therefore, in the method for manufacturing a multilayer ceramic capacitor described in Patent Document 1, when barium titanate produced by the hydrothermal synthesis method described in Patent Document 2 is used as the barium titanate (co-material) to be incorporated into the conductive paste for forming the internal electrode layer, the barium titanate can be arranged relatively uniformly around the Ni particles, thereby reducing contact between Ni particles and slowing down the firing rate of the conductive paste for forming the internal electrode layer. However, when barium titanate produced by the hydrothermal synthesis method is used as the co-material for the conductive paste for forming the internal electrode layer, the continuity of the internal electrode layer obtained by firing is reduced. The object of this disclosure is to provide a multilayer ceramic capacitor with high continuity of the internal electrode layer and a conductive paste that can produce a multilayer ceramic capacitor with high continuity of the internal electrode layer.

[0008] The inventors of this invention have diligently investigated the reason why the continuity of the internal electrode layer obtained by firing decreases when barium titanate produced by hydrothermal synthesis is used as a co-material in a conductive paste for forming the internal electrode layer, and have obtained the following findings. Specifically, when barium titanate is produced by hydrothermal synthesis, barium titanate precipitates in a solution with a high concentration of barium elements, so it is necessary to wash away the excess barium elements with water. During this washing, some of the barium elements in the A-site of the barium titanate are also washed away. Therefore, the barium titanate obtained by hydrothermal synthesis becomes A-site poor barium titanate, meaning that the amount of barium elements in the A-site is insufficient. When this A-site poor barium titanate is used as a co-material in a conductive paste for forming the internal electrode layer, the co-material migrates to the dielectric layer during firing, causing the overall A-site ratio of barium titanate particles in the dielectric layer to decrease. As a result, the barium titanate particles in the dielectric layer grow, and the entire multilayer ceramic capacitor expands, increasing the gaps between the dielectrics. When a portion of the conductive paste for forming the internal electrode layer flows into the gap, the continuity of the internal electrode layer formed by the remaining conductive paste is reduced. Furthermore, as a result of diligent research, the inventors have found that a conductive paste for forming the internal electrode layer containing a specific element different from the main component element can be used to obtain an internal electrode layer with high continuity.

[0009] In other words, the present disclosure relates to the following: [1] A multilayer ceramic capacitor comprising a laminate having alternately stacked dielectric layers and internal electrode layers, wherein the dielectric layers comprise crystalline particles having a perovskite structure with A sites and B sites, and the internal electrode layers comprise a main component which is a metal composed of a metal element (1) and a secondary component which comprises a metal element (2), wherein the metal element (2) comprises a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y and rare earth elements, and the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2-1) in the metal element (2-1) and less than the content (moles) of the metal element (1). [2] The multilayer ceramic capacitor according to [1], wherein the metal element (2-1) is at least one selected from the group consisting of Ba, Ca, and Sr. [3] The multilayer ceramic capacitor according to [1] or [2] above, wherein the content of the metal element (2-1) in the metal element (2) is 100 mol%. [4] The multilayer ceramic capacitor according to any one of [1] to [3] above, wherein the area ratio occupied by the metal element (2-1) in the internal electrode layer in a cross-section in the thickness direction is less than 15%. [5] The multilayer ceramic capacitor according to any one of [1] to [3] above, wherein the area ratio occupied by the metal element (2-1) in the internal electrode layer in a cross-section in the thickness direction is 0.03 to 4.51%. [6] The multilayer ceramic capacitor according to any one of [1] to [3] above, wherein the area ratio occupied by the metal element (2-1) in the internal electrode layer in a cross-section in the thickness direction is 0.05 to 0.75%. [7] A multilayer ceramic capacitor according to any one of [1] to [6], wherein the ratio of A sites to B sites of crystal particles having a perovskite structure in the central part of the dielectric layer (A / B ratio (central part)) is smaller than the ratio of A sites to B sites of crystal particles having a perovskite structure in the interface of the dielectric layer located between the central part and the internal electrode layer (A / B ratio (interface)).[8] The laminate has a first main surface and a second main surface facing each other in the lamination direction, and at least one of the first main surface and the second main surface is a curved surface that curves in a concave shape, as described in any of [1] to [7] above. [9] A conductive paste comprising conductive powder, an additive containing a metal element (2), a dispersant, a binder resin, and an organic solvent, wherein the conductive powder is a metal powder composed of a metal element (1), and the metal element (2) comprises a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements, and the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2-1) in the metal element (2-1), and less than the content (moles) of the metal element (1), as described in

[10] The conductive paste according to [9] above, wherein the metal element (2-1) is at least one selected from the group consisting of Ba, Ca, and Sr.

[11] The conductive paste according to [9] or

[10] , wherein the content of the metal element (2-1) in the metal element (2) is 100 mol%.

[12] The conductive paste according to any one of [9] to

[11] , wherein the content of the metal element (2-1) per 100 mol parts of the metal element (1) is 0.006 to 2.975 mol parts.

[13] The conductive paste according to any one of [9] to

[11] , wherein the content of the metal element (2-1) per 100 mol parts of the metal element (1) is 0.030 to 0.500 mol parts.

[14] A multilayer ceramic capacitor comprising a laminate having alternately stacked dielectric layers and an internal electrode layer, wherein the dielectric layer comprises crystalline particles having a perovskite structure with A sites and B sites, and the internal electrode layer is a fired product of the conductive paste according to any one of [9] to

[13] .

[0010] According to this disclosure, a multilayer ceramic capacitor with high continuity of the internal electrode layer and a conductive paste that makes it possible to obtain a multilayer ceramic capacitor with high continuity of the internal electrode layer are provided.

[0011] This is a perspective view showing a multilayer ceramic capacitor according to an embodiment of the present disclosure. This is a perspective view showing the main body of the multilayer ceramic capacitor in Figure 1. This is a cross-sectional view taken from the line III-III in Figure 1. This is a perspective view showing the process of manufacturing a temporary laminate. This is a perspective view showing the master laminate. This is a perspective view showing a plurality of main body parts obtained by cutting the master laminate. This is a perspective view showing an unfired main body part. This is an SEM backscattered electron photograph of a cross-section of the multilayer ceramic capacitor of Example 1. This is a chart showing the results of elemental analysis by SEM-EDS elemental analysis at the locations indicated by arrows in Figure 8. This is a graph showing the rate of change of the effective T dimension of the main body and multilayer ceramic capacitor in Examples 6, 13, 15 and Comparative Example 2. This is an SEM photograph of a cross-section in the stacking direction of the multilayer ceramic capacitor of Example 6. This is an SEM photograph of a cross-section in the stacking direction of the multilayer ceramic capacitor of Example 13. This is an SEM photograph of a cross-section in the stacking direction of the multilayer ceramic capacitor of Example 15. This is an SEM photograph of a cross-section in the stacking direction of the multilayer ceramic capacitor of Comparative Example 2.

[0012] The present disclosure will be described in detail below with reference to one embodiment. In this disclosure, the notation "XX to YY" means "XX or more and YY or less". In this disclosure, the lower and upper limits of numerical ranges (e.g., ranges of content, etc.) described in steps can be combined independently. In addition, in numerical ranges described in this disclosure, the upper or lower limit of the numerical range may be replaced with the values ​​shown in the examples. In this disclosure, metalloid elements (boron, germanium, arsenic, antimony, tellurium, selenium, polonium, and astatine) are included in metallic elements.

[0013] [Conductive Paste] The conductive paste of the present disclosure comprises conductive powder, an additive containing a metal element (2), a dispersant, a binder resin, and an organic solvent, wherein the conductive powder is a metal powder composed of a metal element (1), the metal element (2) comprises a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements, and the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2-1) in the metal element (2), and less than the content (moles) of the metal element (1).

[0014] The conductive paste of this disclosure makes it possible to obtain a multilayer ceramic capacitor with high continuity of the internal electrode layer. The details of the reason for this are unknown, but it is presumed to be as follows: When an unfired laminate, in which a dielectric layer green sheet and an electrode pattern (electrode layer) formed on the surface of the dielectric layer green sheet using the conductive paste are alternately stacked, is degreased and fired, some of the metal elements (2-1) present in the electrode pattern move to the dielectric layer green sheet. Therefore, when the unfired laminate is fired to obtain a multilayer ceramic capacitor, some of the metal elements (2-1) solid-solve in the A-site of the perovskite structure crystal particles (dielectric particles) in the dielectric layer, and the dielectric particles become A-site rich. As a result, grain growth of the dielectric particles is reduced. When grain growth is reduced and the dielectric particles become finer, the gaps between the dielectric particles become smaller, and it becomes more difficult for the electrode pattern to enter these gaps. As a result, the continuity of the obtained internal electrode layer is improved.

[0015] (Conductive Powder) The conductive powder is a metal powder composed of a metal element (1). All metal elements present in the conductive powder are included in metal element (1). The conductive powder may be composed of only metal element (1). Also included in the conductive powder are metal powders whose surface has been oxidized in whole or in part during manufacturing or storage. Also included in the conductive powder are metal powders that are inevitably mixed in during the manufacturing process and are not originally desirable, but are present in trace amounts and do not affect the properties of the metal product. The metal powder (conductive powder) may be a metal powder composed of one type of metal element, or it may be an alloy powder composed of two or more types of metal elements. The metal element (1) may contain one or more elements selected from the group consisting of nickel (Ni), copper (Cu), iron (Fe), aluminum (Al), and titanium (Ti), or it may consist of one or more elements selected from the group. The metal element (1) may be a metal element other than Ba, Ca, Sr, Y, and rare earth elements, or it may be a metal element other than Ba, Ca, Sr, and Y. The content of one or more elements selected from the group consisting of nickel (Ni), copper (Cu), iron (Fe), aluminum (Al), and titanium (Ti) in the total amount of the metal element (1) may be 60% by mass or more, 80% by mass or more, 90% by mass or more, 99% by mass or more, or 100% by mass.

[0016] (Additive containing metal element (2)) The metal element (2) includes metal element (2-1), which is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements. These metal elements (2-1) readily dissolve in the A-site of crystalline particles (dielectric particles) having a perovskite structure in the dielectric layer, and therefore the dielectric particles tend to become A-site rich. As a result, grain growth of the dielectric particles is reduced. When grain growth is reduced and the dielectric particles are made finer, the gaps between the dielectric particles become smaller, making it difficult for the electrode layer to enter these gaps, and as a result, the continuity of the resulting internal electrode layer is improved. Note that all metal elements present in the additive are included in metal element (2). Metal element (2) may contain only metal element (2-1), or it may contain metal elements other than metal element (2-1).

[0017] <Type of Metal Element (2-1)> The metal element (2-1) is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements. The metal element (2-1) may be at least one selected from the group consisting of Ba, Ca, and Sr, or it may be Ba, from the viewpoint of being more readily selectively dissolved at the A site of the perovskite structure crystal grains (dielectric grains) in the dielectric layer than at the B site.

[0018] <Content of Metal Element (2-1)> The total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2) in the metal element (2), and less than the content (moles) of the metal element (1). When the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2) in the metal element (2), the effects caused by the metal element (2-1) are well exhibited, and the continuity of the resulting internal electrode layer is improved. Furthermore, when the total amount (moles) of the metal element (2-1) is less than the content (moles) of the metal element (1), an internal electrode layer with high conductivity and high continuity can be manufactured.

[0019] The total amount (moles) of the metal element (2-1) may be greater than the total amount (moles) of the metal elements (2) other than the metal element (2), and less than the content (moles) of the metal element (1). If the total amount (moles) of the metal element (2-1) is greater than the total amount (moles) of the metal elements (2) other than the metal element (2), the effects due to the metal element (2-1) are well exhibited, and the continuity of the resulting internal electrode layer is improved. If the total amount (moles) of the metal element (2-1) is less than the content (moles) of the metal element (1), an internal electrode layer with high conductivity and high continuity can be manufactured.

[0020] The content (moles) of the most abundant metal element among the metal elements (2-1) may be greater than the content (moles) of each metal element other than metal element (2) among the metal elements (2), and less than the content (moles) of metal element (1). If the content (moles) of the most abundant metal element among the metal elements (2-1) is greater than the content (moles) of each metal element other than metal element (2) among the metal elements (2), the effect due to metal element (2) is well exhibited, and the continuity of the resulting internal electrode layer is improved. Furthermore, if the content (moles) of the most abundant metal element among the metal elements (2-1) is less than the content (moles) of metal element (1), an internal electrode layer with high conductivity and high continuity can be manufactured.

[0021] The content (moles) of the most abundant metal element among the metal elements (2-1) may be greater than the total amount (moles) of metal elements other than metal element (2) among the metal elements (2), and less than the content (moles) of metal element (1). If the content (moles) of the most abundant metal element among the metal elements (2-1) is greater than the total amount (moles) of metal elements other than metal elements (2) among the metal elements (2), the effect due to metal element (2) is well exhibited, and the continuity of the resulting internal electrode layer is improved. Furthermore, if the content (moles) of the most abundant metal element among the metal elements (2-1) is less than the content (moles) of metal element (1), an internal electrode layer with high conductivity and continuity can be manufactured.

[0022] The content of at least one element selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements, which is metal element (2-1), in the metal element (2) may be 50 to 100 mol%, 70 to 100 mol%, 90 to 100 mol%, 95 to 100 mol%, or 100 mol%, from the viewpoint of improving the continuity of the obtained internal electrode layer. Note that a content of metal element (2-1) in metal element (2) of 100 mol% means that all of the metal element (2) contained in the additive is metal element (2-1). Note that trace amounts of impurities that are inevitably detected during measurement may be included in the metal element (2). The content of at least one element selected from the group consisting of Ba, Ca, and Sr in the metal element (2) may be 50 to 100 mol%, 80 to 100 mol%, 90 to 100 mol%, 95 to 100 mol%, or 99 to 100 mol%, from the viewpoint of improving the continuity of the obtained internal electrode layer. Trace amounts of impurity components that are unavoidable to be detected during measurement may be present.

[0023] <Type and Content of Additive> The additive containing the metal element (2) may be a metal compound containing the metal element (2). When the additive is a metal compound containing the metal element (2), compared with the case where the additive is a metal composed of the metal element (2), the affinity with the conductive powder (metal powder) in the conductive paste is low, and the affinity with the dielectric particles (crystalline particles) in the dielectric layer is high. Therefore, when manufacturing a multilayer ceramic capacitor using the conductive paste as a material for the internal electrode layer, the metal element (2) contained in the metal compound easily moves from the internal electrode layer to the dielectric layer. As a result, a part of the metal element (2-1) is solid-solved in the A site of the crystalline particles (dielectric particles) having a perovskite structure in the dielectric layer, and the dielectric particles become in an A-site-rich state. Consequently, the grain growth of the dielectric particles is reduced. When the grain growth is reduced and the dielectric particles are micronized, the gap between the dielectric particles becomes small, and it becomes difficult for the electrode layer to enter the gap. As a result, the continuity of the obtained internal electrode layer is improved.

[0024] The metal compound containing the metal element (2) may be one or more selected from the group consisting of carbonate, oxide, hydroxide, chloride, and sulfide. Examples of the carbonate include barium carbonate (BaCO ３ ), calcium carbonate (CaCO ３ ), strontium carbonate (SrCO ３ ), etc. Examples of the oxide include barium oxide (BaO), calcium oxide (CaO), strontium oxide (SrO), yttrium oxide (Y ２ O ３ ), dysprosium oxide (Dy ２ O ３ ), etc. Examples of the hydroxide include barium hydroxide (Ba(OH) ２ ), calcium hydroxide (Ca(OH) ２ ), strontium hydroxide (Sr(OH) ２ ), etc. Examples of the chloride include barium chloride (BaCl ２ ), calcium chloride (CaCl ２ ), strontium chloride (SrCl ２ ), yttrium chloride (YCl３ Examples include barium sulfate (BaSO4). ４ ), calcium sulfate (CaSO4) ４ ), strontium sulfate (SrSO ４ ), yttrium sulfide (Y ２ S ３ ) are some examples.

[0025] The content of the metal compound containing metal element (2) in the total amount of additives containing metal element (2) may be 50 to 100% by mass, 80 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, or 100% by mass.

[0026] The content of one or more compounds selected from the group consisting of barium compounds, calcium compounds, strontium compounds, and dysprosium compounds in the total amount of additives containing metal element (2) may be 50 to 100% by mass, 80 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, or 100% by mass. Here, a barium compound means a compound containing only barium as the metal element. The same applies to calcium compounds, strontium compounds, and dysprosium compounds. ３ ), calcium carbonate (CaCO3) ３ ), strontium carbonate (SrCO ３ ), and dysprosium oxide (Dy ２ O ３ The content of one or more selected from the group consisting of ) may be 50 to 100% by mass, 80 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, or 100% by mass.

[0027] (Dispersant) Depending on the type of additive to be added, a known dispersant can be appropriately selected.

[0028] (Binder resin) The binder resin may be one or more selected from the group consisting of ethylcellulose and polyvinyl butyral.

[0029] (Organic Solvents) Organic solvents can be appropriately selected that can disperse or dissolve the conductive powder, binder resin, and additives, and that do not significantly affect the dielectric layer. Examples of organic solvents include terpineols such as α-terpineol, cyclohexanone, diethylene glycol monobutyl ether acetate, and dihydroterpineol acetate.

[0030] (Content of each component in the conductive paste) The content of conductive powder in the total amount of conductive paste may be 20 to 80% by mass, 30 to 70% by mass, or 40 to 60% by mass, from the viewpoint of obtaining a highly continuous internal electrode layer. The content of additives containing metal element (2) per 100 parts by mass of conductive powder may be 0.001 to 40 parts by mass, 0.01 to 20 parts by mass, or 0.02 to 15 parts by mass, from the viewpoint of obtaining a highly continuous internal electrode layer. The content of dispersant in the total amount of conductive paste is not particularly limited, but may be, for example, 0.01 to 5.0% by mass, 0.05 to 5.0% by mass, or 0.1 to 1.0% by mass. The content of binder resin in the total amount of conductive paste is not particularly limited, but may be, for example, 0.1 to 10% by mass, 0.5 to 5.0% by mass, or 1.0 to 5.0% by mass. The content of organic solvent in the total amount of conductive paste is not particularly limited, but may be, for example, 20 to 80% by mass, 40 to 70% by mass, or 50 to 60% by mass.

[0031] The total content of conductive powder, additive containing metal element (2), dispersant, binder resin, and organic solvent in the conductive paste may be 80 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, 99 to 100% by mass, or 100% by mass. The total content of conductive powder, additive containing metal element (2-1), dispersant, binder resin, and organic solvent in the conductive paste may be 80 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, 99 to 100% by mass, or 100% by mass.

[0032] The content of metal element (2) per 100 mole parts of metal element (1) may be 0.005 to 5.00 mole parts, 0.005 to 3.00 mole parts, 0.006 to 2.975 mole parts, 0.030 to 0.500 mole parts, 0.05 to 0.40 mole parts, or 0.10 to 0.30 mole parts. The content of metal element (2-1) per 100 mole parts of metal element (1) may be 0.005 to 5.00 mole parts, 0.005 to 3.00 mole parts, 0.006 to 2.975 mole parts, 0.030 to 0.500 mole parts, 0.05 to 0.40 mole parts, or 0.10 to 0.30 mole parts. When the content is 0.005 mol parts or more, the metal element (2-1) is solid-dissolved in the A-site of the dielectric particles (crystalline particles) in the dielectric layer, reducing the grain growth of the dielectric particles (crystalline particles). This reduces the flow of conductive paste between the dielectric particles (crystalline particles), improving the continuity of the internal electrode layer. When the content is 5.00 mol parts or less, the high firing temperature caused by a large amount of additive containing the metal element (2-1) flowing from the internal electrode layer to the dielectric layer is reduced, improving the continuity of the internal electrode layer. Furthermore, when the content is 0.03 mol parts or more, it tends to be easier to obtain multilayer ceramic capacitors with high capacitance. When the content is 0.50 mol parts or less, it tends to be easier to obtain multilayer ceramic capacitors with a long Mean Time To Failure (MTTF).

[0033] (Method for manufacturing conductive paste) The conductive paste of this disclosure can be manufactured by mixing conductive powder, an additive containing a metal element (2), a dispersant, a binder resin, and an organic solvent. For example, a first slurry may be prepared by mixing an additive containing a metal element (2), a dispersant, and an organic solvent, and a second slurry may be prepared by mixing conductive powder, a dispersant, a binder resin, and an organic solvent, and then the conductive paste may be prepared by mixing the first slurry and the second slurry. Alternatively, the conductive paste may be prepared by mixing the first slurry and the second slurry and then performing a dispersion treatment using a three-roll machine or the like.

[0034] [Multilayer ceramic capacitor according to the first embodiment] A multilayer ceramic capacitor according to the first embodiment of the present disclosure comprises a laminate having alternately stacked dielectric layers and internal electrode layers, wherein the dielectric layers comprise crystalline particles having a perovskite structure with A sites and B sites, and the internal electrode layers comprise a main component which is a metal composed of a metal element (1) and a secondary component which comprises a metal element (2), wherein the metal element (2) comprises a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y and rare earth elements, and the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2-1) in the metal element (2), and less than the content (moles) of the metal element (1).

[0035] (An example of the structure of a multilayer ceramic capacitor) Next, an example of a multilayer ceramic capacitor of the present disclosure will be described using Figures 1 to 3. Figure 1 is a perspective view showing a multilayer ceramic capacitor 1 according to an example of the present disclosure, Figure 2 is a perspective view showing the laminate 2 in the multilayer ceramic capacitor 1 of Figure 1, and Figure 3 is a cross-sectional view along the line III-III in Figure 1.

[0036] As shown in Figure 1, the multilayer ceramic capacitor 1 includes a laminate 2. As shown in Figure 2, the laminate 2 has a substantially rectangular parallelepiped shape. The laminate 2 has a first surface 7a and a second surface 7b facing each other in a third direction (z direction in Figures 1 to 3), a first end surface 8a and a second end surface 8b facing each other in a first direction (x direction in Figures 1 to 3), and a first side surface 9a and a second side surface 9b facing each other in a second direction (y direction in Figures 1 to 3). Hereinafter, the first surface 7a and the second surface 7b may be collectively referred to as main surfaces 7a and 7b, the first end surface 8a and the second end surface 8b may be collectively referred to as end surfaces 8a and 8b, and the first side surface 9a and the second side surface 9b may be collectively referred to as side surfaces 9a and 9b. The main surfaces 7a and 7b may be perpendicular to the third direction, the end surfaces 8a and 8b may be perpendicular to the first direction, and the side surfaces 9a and 9b may be perpendicular to the second direction. At least one of the main surfaces 7a and 7b in the laminate 2 may be a curved surface that curves in a concave shape.

[0037] As shown in Figure 3, the laminate 2 is constructed by alternately stacking dielectric layers 5 and internal electrode layers 6. The dielectric layers 5 and internal electrode layers 6 are stacked in a third direction. The internal electrode layers 6 are exposed on the first side surface 9a and the second side surface 9b. As shown in Figure 2, the ends of the internal electrode layers 6 exposed on the first side surface 9a and the ends exposed on the second side surface 9b are covered by the side margin portion 3 and are not exposed to the outside. In addition, the internal electrode layers 6 are exposed on either the first end surface 8a or the second end surface 8b depending on their polarity. As shown in Figure 3, the ends of the internal electrode layers 6 exposed on the first end surface 8a and the ends exposed on the second end surface 8b are covered by the first external electrode 4a and the second external electrode 4b, respectively, and are electrically connected to the first external electrode 4a and the second external electrode 4b.

[0038] As shown in Figure 2, the side margin portion 3 is located on the first side surface 9a and the second side surface 9b of the laminate 2. The side margin portion 3 has an outer surface 3a opposite to the surface facing the laminate 2. The side margin portion 3 electrically insulates the ends of the internal electrode layers 6 with different polarities that are exposed on the side surfaces 9a and 9b. In addition, the side margin portion 3 physically protects the ends of the internal electrode layers 6 that are exposed on the side surfaces 9a and 9b. Hereafter, the laminate 2 and the side margin portion 3 may be collectively referred to as the main body portions 2 and 3.

[0039] As shown in Figure 3, both ends of the laminate 2 in the third direction may be made of a cover layer 21.

[0040] As shown in Figures 1 and 3, the multilayer ceramic capacitor 1 further comprises a first external electrode 4a and a second external electrode 4b. The first external electrode 4a is located from the first end face 8a to the first surface 7a, the second surface 7b, and the outer surface 3a. The first external electrode 4a is electrically connected to the internal electrode layer 6 exposed on the first end face 8a. The second external electrode 4b is located from the second end face 8b to the first surface 7a, the second surface 7b, and the outer surface 3a. The second external electrode 4b is electrically connected to the internal electrode layer 6 exposed on the second end face 8b. Hereafter, the first external electrode 4a and the second external electrode 4b may be collectively referred to as external electrodes 4a and 4b.

[0041] The external electrodes 4a and 4b are composed of one or more conductive layers. The external electrodes 4a and 4b may also include a first layer 41 and a second layer 42, as shown in Figure 3. The first layer 41 is also called the base layer. The second layer 42 is also called the outer layer. The base layer 41 is in direct contact with the main body portions 2 and 3 and is connected to the ends of the internal electrode layer 6 that are exposed on the end faces 8a and 8b. The outer layer 42 covers the side of the base layer 41 opposite to the laminate 2 side. By composing the external electrodes 4a and 4b with multiple conductive layers, the adhesion between the external electrodes 4a and 4b and the main body portions 2 and 3 can be improved. Furthermore, the wettability of the external electrodes 4a and 4b to the conductive bonding material used when mounting the multilayer ceramic capacitor 1 to a substrate can be improved. As a result, the reliability of the multilayer ceramic capacitor 1 and the mounting structure including the multilayer ceramic capacitor 1 can be improved.

[0042] (Internal electrode layer) The internal electrode layer comprises a main component which is a metal composed of a metal element (1), and a secondary component which includes a metal element (2), wherein the metal element (2) includes a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements, and the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2-1) in the metal element (2), and less than the content (moles) of the metal element (1).

[0043] The internal electrode layer has high conductivity because it contains a main component which is a metal composed of metal element (1). In this disclosure, "main component" in "main component which is a metal composed of metal element (1)" means the component with the largest content (mass%) in the internal electrode layer, and the content of the main component in the internal electrode layer may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more. The internal electrode layer also contains a secondary component which is a metal element (2), and the metal element (2) is a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements. This improves the continuity of the obtained internal electrode layer. Furthermore, since the total amount (moles) of the metal element (2-1) is less than the content (moles) of the metal element (1), the internal electrode layer is sufficiently formed by the metal composed of metal element (1), and therefore the continuity of the internal electrode layer is improved.

[0044] <Main Component> The internal electrode layer contains a main component which is a metal composed of metal element (1). The main component which is a metal composed of metal element (1) may be composed of one type of metal element, or it may be an alloy composed of two or more types of metal elements. From the viewpoint of conductivity, cost and availability, metal element (1) may include one or more elements selected from the group consisting of nickel (Ni), copper (Cu), iron (Fe), aluminum (Al), and titanium (Ti), or it may be one or more elements selected from the group. The metal element (1) may be a metal element other than Ba, Ca, Sr, Y, and rare earth elements, or it may be a metal element other than Ba, Ca, Sr, and Y. The content of nickel (Ni) in 100 mol% of the total amount of metal element (1) may be 50 mol% or more, 60 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 99 mol% or more, or 100 mol%. The content of each metal element (including the metal elements described later) in the internal electrode layer can be calculated from the raw materials of the conductive paste, which is the raw material of the internal electrode layer. The relative amounts of each metal element (including the metal elements described later) in the internal electrode layer can be determined by using an EDS (energy-dispersive X-ray spectrometer) to analyze the cross-section in the thickness direction of the multilayer ceramic capacitor (a cross-section parallel to the thickness direction (stack direction) of the multilayer ceramic capacitor) and identifying the elements contained in the parts with a different color tone from the main component in the internal electrode layer using EDS point analysis, and then measuring the total area of ​​the parts with a different color tone once the elements have been identified. Alternatively, EDS mapping analysis can be performed to measure the area of ​​a specific detection intensity, calculate the area ratio of each metal element in the cross-section, and consider this as a molar ratio for determination. The content of each metal element in other layers can be calculated using the same method.

[0045] <Sub-components> The internal electrode layer contains a sub-component comprising a metal element (2). The metal element (2) comprises a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements. This improves the continuity of the internal electrode layer.

[0046] <Type of Metal Element (2-1)> The metal element (2-1) may be at least one selected from the group consisting of Ba, Ca, and Sr, from the viewpoint of being more readily solid-dissolved at the A site of the perovskite structure crystal grains (dielectric grains) in the dielectric layer, or it may be Ba.

[0047] <Content of Metal Element (2-1)> The total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2) in the metal element (2), and less than the content (moles) of the metal element (1). When the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2) in the metal element (2), the effects caused by the metal element (2-1) are well exhibited, and the continuity of the internal electrode layer is improved. Also, when the total amount (moles) of the metal element (2-1) is less than the content (moles) of the metal element (1), the internal electrode layer becomes highly conductive and has high continuity.

[0048] The total amount (moles) of the metal element (2-1) may be greater than the total amount (moles) of the metal elements (2) other than the metal element (2), and less than the content (moles) of the metal element (1). If the total amount (moles) of the metal element (2-1) is greater than the total amount (moles) of the metal elements (2) other than the metal element (2), the effects due to the metal element (2-1) are well exhibited, and the continuity of the resulting internal electrode layer is improved. If the total amount (moles) of the metal element (2-1) is less than the content (moles) of the metal element (1), an internal electrode layer with high conductivity and high continuity is obtained.

[0049] The content (moles) of the most abundant metal element among the metal elements (2-1) may be greater than the content (moles) of each metal element other than metal element (2) among the metal elements (2), and less than the content (moles) of metal element (1). If the content (moles) of the most abundant metal element among the metal elements (2-1) is greater than the content (moles) of each metal element other than metal element (2) among the metal elements (2), the effect due to metal element (2) is well exhibited, and the continuity of the internal electrode layer is improved. Also, if the content (moles) of the most abundant metal element among the metal elements (2-1) is less than the content (moles) of metal element (1), the internal electrode layer will have high conductivity and high continuity.

[0050] The content (moles) of the most abundant metal element among the metal elements (2-1) may be greater than the total amount (moles) of metal elements other than metal element (2) among the metal elements (2), and less than the content (moles) of metal element (1). If the content (moles) of the most abundant metal element among the metal elements (2-1) is greater than the total amount (moles) of metal elements other than metal element (2) among the metal elements (2), the effect due to metal element (2) is well exhibited, and the continuity of the internal electrode layer is improved. Also, if the content (moles) of the most abundant metal element among the metal elements (2-1) is less than the content (moles) of metal element (1), the internal electrode layer will have high conductivity and high continuity.

[0051] The content of metal element (2-1) in 100 mol% of metal element (2) may be 50 to 100 mol%, 70 to 100 mol%, 80 to 100 mol%, 90 to 100 mol%, 95 to 100 mol%, or 100 mol%, from the viewpoint of improving the continuity of the internal electrode layer.

[0052] The content of at least one element selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements in the metal element (2) may be 50 to 100% by mass, 70 to 100% by mass, 80 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, or 100% by mass, from the viewpoint of improving the continuity of the obtained internal electrode layer. The content of at least one element selected from the group consisting of Ba, Ca, and Sr in the total amount of 100 mol% of the metal element (2) may be 50 to 100 mol%, 70 to 100 mol%, 80 to 100 mol%, 90 to 100 mol%, 95 to 100 mol%, 99 to 100 mol%, or 100 mol%, from the viewpoint of improving the continuity of the obtained internal electrode layer.

[0053] <Types of auxiliary components> The auxiliary component containing the metal element (2) may be a metal compound composed of the metal element (2). When the auxiliary component is a metal compound composed of the metal element (2), the continuity of the resulting internal electrode layer is improved.

[0054] The metal compound composed of metal element (2) may be one or more selected from the group consisting of carbonates, oxides, hydroxides, chlorides, sulfides, etc. The metal compound composed of metal element (2) may also be an oxide. As a carbonate, barium carbonate (BaCO2) ３ ), calcium carbonate (CaCO3) ３ ), strontium carbonate (SrCO ３ Examples include barium oxide (BaO), calcium oxide (CaO), strontium oxide (SrO), and yttrium oxide (Y). ２ O ３ ), dysprosium oxide (Dy ２ O ３ Examples include barium hydroxide (Ba(OH)) ２ ), calcium hydroxide (Ca(OH) ２ ), strontium hydroxide (Sr(OH) ２Examples include barium chloride (BaCl). ２ ), calcium chloride (CaCl ２ ), strontium chloride (SrCl ２ ), yttrium chloride (YCl ３ Examples include barium sulfate (BaSO4). ４ ), calcium sulfate (CaSO4) ４ ), strontium sulfate (SrSO ４ ), yttrium sulfide (Y ２ S ３ ) are some examples.

[0055] The average particle size of the subcomponent containing the metal element (2) may be 5 to 100 nm.

[0056] <Content of each component in the auxiliary components> The content of the metal compound composed of metal element (2) in the total amount of the auxiliary components containing metal element (2) may be 50 to 100% by mass, 70 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, or 100% by mass. The content of the metal compound composed of metal element (2) in the total amount of the auxiliary components containing metal element (2) in the internal electrode layer can be considered to be the same as the content of the metal compound composed of metal element (2) in the total amount of the auxiliary components containing metal element (2) in the conductive paste.

[0057] In the total amount of the by-components containing the aforementioned metal element (2), barium oxide (BaO), calcium oxide (CaO), strontium oxide (SrO), and dysprosium oxide (Dy ２ O ３ The content of one or more selected from the group consisting of ) may be 50 to 100% by mass, 70 to 100% by mass, 90 to 100% by mass, 95 to 100% by mass, or 100% by mass.

[0058] <Area ratio (%) occupied by metal element (2-1) in the internal electrode layer> In the cross-section in the thickness direction of the multilayer ceramic capacitor, the area ratio occupied by metal element (2-1) in the internal electrode layer may be less than 15%. If the area ratio is less than 15%, the internal electrode layer is sufficiently formed by the metal composed of metal element (1), and therefore the continuity of the internal electrode layer is improved. The area ratio occupied by metal element (2-1) in the internal electrode layer may be 0.03 to 10%, 0.04 to 10%, 0.03 to 4.51%, or 0.05 to 0.75%. If the area ratio is 0.04% or more, the continuity of the internal electrode layer is improved. Furthermore, if the area ratio is 10% or less, the increase in firing temperature due to a large amount of metal element (2-1) flowing from the internal electrode layer to the dielectric layer is reduced, and the continuity of the internal electrode layer is improved. Furthermore, if the area ratio is 0.05% or higher, it tends to be easier to obtain a multilayer ceramic capacitor with a large capacitance. If the area ratio is 0.75% or lower, it tends to be easier to obtain a multilayer ceramic capacitor with a long Mean Time To Failure (MTTF). The area ratio can be calculated by binarizing the backscattered electron image (secondary electron image) in the cross-section in the thickness direction of the multilayer ceramic capacitor, calculating the area of ​​the internal electrode layer present in the entire region of the binarized image and the area occupied by the metal element (2-1) within the internal electrode layer, and using the following formula: Area ratio = (Area occupied by metal element (2-1)) / (Area of ​​internal electrode layer) Binarization can be performed by known methods, for example, using commercially available image processing software. Specifically, the area ratio can be calculated by the method described in the examples. Furthermore, in cases where both metal element (2-1) and metal element (2-2) other than metal element (2-1) are present as metal element (2) in the internal electrode layer, it may not be possible to separate and observe metal element (2-1) and metal element (2-2) other than metal element (2-1) in the backscattered electron image (secondary electron image).In that case, the area ratio (%) of the region where metal element (2-1) and metal element other than metal element (2-2) are mixed can be measured, elemental analysis can be performed on that region using SEM-EDS, and the area ratio (%) of metal element (2-1) can be calculated by multiplying the area ratio (%) by the ratio of metal element (2-1) and metal element other than metal element (2-2) obtained from the elemental analysis.

[0059] <Area ratio (%) occupied by metal element (1) in the internal electrode layer> In the cross-section in the thickness direction of the multilayer ceramic capacitor, the area ratio occupied by metal element (1) in the internal electrode layer may exceed 85%. When this area ratio exceeds 85%, the internal electrode layer is sufficiently formed by the metal composed of metal element (1), and therefore the continuity of the internal electrode layer is improved. The area ratio occupied by metal element (1) in the internal electrode layer may be 90 to 99.96%. When this area ratio is 90% or more, the continuity of the internal electrode layer is improved. Furthermore, when this area ratio is 99.96% or less, the increase in firing temperature due to a large amount of metal element (2-1) flowing from the internal electrode layer to the dielectric layer is reduced, and the continuity of the internal electrode layer is improved. From this viewpoint, this area ratio may be 90 to 99.96%, 95 to 99.96%, or 99 to 99.96%. The area ratio can be calculated by binarizing the backscattered electron image (secondary electron image) in the cross-section in the thickness direction of the multilayer ceramic capacitor, calculating the area of ​​the internal electrode layer present in the entire region of the binarized image and the area occupied by the metal element (1) within the internal electrode layer, and then using the following formula: Area ratio = (Area occupied by metal element (1)) / (Area of ​​internal electrode layer) Binarization can be performed by known methods, for example, using commercially available image processing software. Specifically, the area ratio can be calculated by the method described in the examples.

[0060] (Dielectric layer) The dielectric layer contains crystalline grains having a perovskite structure with A sites and B sites.

[0061] The crystalline grains having a perovskite structure with sites A and B are made of barium titanate (BaTiO). ３ ), calcium titanate (CaTiO ３ ), strontium titanate (SrTiO ３ ), barium zirconate (BaZrO ３ ) may be other types, such as barium titanate (BaTiO ３ ) is also acceptable.

[0062] In the dielectric layer, crystalline particles having a perovskite structure with A-sites and B-sites may be the main component. In this disclosure, "main component" of the dielectric layer means the component with the largest content (mass%) in the dielectric layer. The content of the crystalline particles in the total amount of the dielectric layer may be 80% by mass or more, 90% by mass or more, 95% by mass or more, or 99% by mass or more.

[0063] In the dielectric layer, the ratio of A sites to B sites of perovskite structure crystal particles in the central part of the dielectric layer (A / B ratio (central part)) may be smaller than the ratio of A sites to B sites of perovskite structure crystal particles in the interface of the dielectric layer located between the central part and the internal electrode layer (A / B ratio (interface)). When the A / B ratio (central part) is smaller than the A / B ratio (interface), the particle size of the crystal particles in the central part grows larger, thus improving the dielectric properties. Conversely, when the A / B ratio (interface) is larger than the A / B ratio (central part), the grain growth of crystal particles at the interface is reduced, improving the continuity of the internal electrode layer.

[0064] Here, "dielectric layer interface" refers to the region of the dielectric layer between a pair of adjacent internal electrode layers, from the interface with one internal electrode layer to a position 1 / 4 of the thickness in the thickness direction of the dielectric layer (first interface), and from the interface with the other internal electrode layer to a position 1 / 4 of the thickness in the thickness direction of the dielectric layer (second interface). Furthermore, "central part of the dielectric layer" refers to the region of the dielectric layer between the pair of adjacent internal electrode layers, excluding the first interface and the second interface. In other words, "central part of the dielectric layer" refers to the region of the dielectric layer between the pair of adjacent internal electrode layers, from a position 1 / 4 of the thickness in the thickness direction of the dielectric layer from the interface with one internal electrode layer to a position 1 / 4 of the thickness in the thickness direction of the dielectric layer from the interface with the other internal electrode layer. Furthermore, the measurement position for the A / B ratio (central part) may be the central position in the thickness direction (stacking direction) of the central part, that is, a position that is 1 / 2 of the thickness of the dielectric layer from the interface with the internal electrode layer in the thickness direction. The measurement position for the A / B ratio (interface part) may be the central position in the thickness direction (stacking direction) of the interface part, that is, a position that is 1 / 8 of the thickness of the dielectric layer from the interface with the internal electrode layer in the thickness direction.

[0065] The A / B ratio (central portion) may be 0.970 to 1.030, 0.980 to 1.020, or 0.990 to 1.010, from the viewpoint of improving the continuity of the internal electrode layer and improving the dielectric properties of the multilayer ceramic capacitor. The A / B ratio (interface portion) may be 1.000 to 1.200, 1.020 to 1.100, or 1.050 to 1.100, from the viewpoint of improving the continuity of the internal electrode layer and improving the dielectric properties of the multilayer ceramic capacitor. The A / B ratio (central portion) and the A / B ratio (interface portion) can be measured by the measurement method described in the examples. Furthermore, the ratio of the A / B ratio (central part) to the A / B ratio (interface part) (central part / interface part) may be 0.900 to 1.010, 0.920 to 0.990, or 0.940 to 0.970, from the viewpoint of improving the continuity of the internal electrode layer and improving the dielectric properties of the multilayer ceramic capacitor.

[0066] (External Electrode) The external electrode is composed of one or more conductive layers. The external electrode may be composed of a base layer and an outer layer. The base layer may be composed of a metallic material. Examples of metallic materials used for the base layer include metals such as Ni, Cu, Ag, Pd, Au, or alloys made of these metals. The base layer may be formed using thin film formation techniques such as plating, sputtering, or vapor deposition, or it may be formed using thick film formation techniques such as dip lithography, screen printing, or gravure printing.

[0067] The outer layer may be composed of a metallic material. Examples of metallic materials that can be used for the outer layer include metals such as Ni, Cu, Au, and Sn. The outer layer may be formed using thin-film formation techniques such as electroless plating or electrolytic plating.

[0068] (Side margin portion) The side margin portion may be made of an insulating material. The side margin portion may be made of a ceramic material. In this case, the side margin portion can have insulating properties and relatively high mechanical strength. Also, when the side margin portion is made of a ceramic material, it is possible to fire the laminate and the side margin portion at the same time. The side margin portion may be made of, for example, BaTiO ３ CaTiO ３ SrTiO ３ BaZrO ３ It may be composed of ceramic materials mainly composed of the following. The side margin portion may be composed of the same ceramic material as the ceramic material constituting the dielectric layer, in which case, as described later, it is possible to create multiple main body portions by cutting the master laminate. Note that in Figure 1, the boundary between the laminate and the side margin portion is shown by a dashed line, but the actual boundary is not clearly visible. The thinner the thickness of the side margin portion, the smaller and larger the multilayer ceramic capacitor 1 can be. The side margin portion may have a thickness of, for example, about 30 μm or less.

[0069] (Cover layer) The cover layer may be made of an insulating material. For example, the cover layer may be made of BaTiO ３ CaTiO ３ SrTiO ３ BaZrO ３ The covering layer may be composed of a ceramic material mainly consisting of the above.

[0070] (Dimensions, etc.) As long as the characteristics of a multilayer ceramic capacitor can be ensured, the thinner the thickness of the internal electrode layer, the more internal defects caused by internal stress during firing or voltage application of the laminate can be reduced, thereby improving the reliability of the multilayer ceramic capacitor. The internal electrode layer may have a thickness of, for example, 1.5 μm or less. The internal electrode layer may be 0.10 to 1.0 μm, 0.20 to 0.50 μm, or 0.25 to 0.40 μm. The thickness of the internal electrode layer can be determined by image analysis of the cross-section in the thickness direction of the multilayer ceramic capacitor. For example, by using a binarized image obtained by image analysis processing of a backscattered electron image (secondary electron image) in the cross-section in the thickness direction of the multilayer ceramic capacitor, the sum of the areas of the internal electrode layer present in the entire region of the binarized image and the sum of the lengths of the internal electrode layer can be calculated, and the thickness of the internal electrode layer can be calculated using the following formula: Thickness of internal electrode layer (μm) = Sum of areas of internal electrode layer (μm) ２ ) / Total length of internal electrode layers (μm) Specifically, this can be measured by the method described in the examples.

[0071] The thinner the dielectric layer, the greater the capacitance of the multilayer ceramic capacitor. The thickness of the dielectric layer may be, for example, 0.1 to 10 μm, 0.3 to 2.0 μm, or 0.3 to 1.0 μm. The thickness of the dielectric layer can be measured by the same method as the measurement of the thickness of the internal electrode layer described above.

[0072] In a multilayer ceramic capacitor, at least one of the first surface and the second surface facing each other in the thickness direction may be a curved surface with a central portion concave in the thickness direction. That is, one of the first surface and the second surface facing each other in the thickness direction may be a curved surface with a central portion concave in the thickness direction. Both the first surface and the second surface facing each other in the thickness direction may be curved surfaces with a central portion concave in the thickness direction.

[0073] [Method for manufacturing a multilayer ceramic capacitor according to the first embodiment] The multilayer ceramic capacitor of the present disclosure can be manufactured by firing an unfired laminate, which is composed of alternating layers of a green sheet containing dielectric powder and an organic resin and an internal electrode pattern.

[0074] (An example of a method for manufacturing a multilayer ceramic capacitor) Next, an example of a method for manufacturing the multilayer ceramic capacitor 1 shown in Figures 1 to 3 will be explained using Figures 4 to 7. Figure 4 is a perspective view showing the process of manufacturing a temporary laminate, Figure 5 is a perspective view showing the master laminate, Figure 6 is a perspective view showing multiple main body parts obtained by cutting the master laminate, and Figure 7 is a perspective view showing the unfired main body parts.

[0075] <Preparation of ceramic slurry> First, as the material for the dielectric layer 5, BaTiO ３ CaTiO ３ SrTiO ３ Prepare a raw material powder mainly consisting of dielectric powders such as (Mg) ２ CO ３ ) powder, dysprosium oxide (Dy ２ O ３ ) Powder, manganese carbonate (MnCO3) ３ ) Powders, glass powders, etc. may be added. Glass powders include, for example, SiO ２ -BaO-CaO based glass powder may be used. Next, an organic vehicle is mixed with the prepared raw material powder to prepare a ceramic slurry. The organic vehicle used to prepare the ceramic slurry may be, for example, a resin such as a butyral resin dissolved in a solvent which is a mixture of ethyl alcohol and toluene.

[0076] <Manufacturing of Green Sheets> Next, using the prepared ceramic slurry, a ceramic green sheet (hereinafter simply referred to as a green sheet) 13, which will become the dielectric layer 5, is formed by a sheet molding method such as the doctor blade method or the die coater method. The average thickness of the green sheet 13 may be, for example, about 0.5 to 10 μm. In the manufacturing method described here, the green sheet 13 not only constitutes the dielectric layer 5 but also constitutes the side margin portion 3.

[0077] <Preparation of conductive paste> The conductive paste can be prepared as described above.

[0078] <Manufacturing of Electrode Pattern> Next, a pattern sheet 14 is formed on the main surface of the green sheet 13 using conductive paste, with the electrode pattern that will become the internal electrode layer 6 printed on it (see Figure 4). The electrode pattern can be printed using a printing method such as screen printing or gravure printing.

[0079] <Manufacturing of the base laminate> Next, as shown in Figure 4, a temporary laminate is created by stacking a predetermined number of pattern sheets 14 on top of a predetermined number of stacked green sheets 13, and then stacking a predetermined number of green sheets 13. The predetermined number of stacked green sheets 13 become the cover layer 21. By applying pressure to the temporary laminate in the stacking direction, a base laminate 15 as shown in Figure 5 is obtained. The temporary laminate can be applied pressure using, for example, a hydrostatic press.

[0080] <Manufacturing of Unfired Main Body Parts 2 and 3> Next, multiple unfired main body parts 2 and 3 are produced as shown in Figure 6 by cutting the base laminate 15 along the virtual dividing line 16. The base laminate 15 can be cut using, for example, a push-cutting machine, a dicing saw device, etc. Figure 7 shows the unfired main body parts 2 and 3. Since the unfired main body parts 2 and 3 have the same structure as the fired main body parts 2 and 3, the terms and reference numerals such as dielectric layer 5, internal electrode layer 6, main surfaces 7a and 7b, end surfaces 8a and 8b, and side surfaces 9a and 9b will be used for the unfired main body parts 2 and 3 as well.

[0081] <Degreasing Treatment> Next, the unfired main body parts 2 and 3 are degreased in an atmospheric atmosphere, an inert gas atmosphere, or a reducing atmosphere. The degreasing treatment may be carried out under atmospheric pressure or under reduced pressure.

[0082] <Firing Process> Next, the degreased main body parts 2 and 3 are fired in a reducing atmosphere. The atmospheric gas is, for example, hydrogen (H ２ ) and nitrogen (N ２ ) may be a mixed gas. The firing temperature may be, for example, around 1000 to 1300°C, and the heating rate may be, for example, around 1000 to 12000°C / hr, or around 8000 to 12000°C / hr.

[0083] <Re-oxidation treatment> Next, the main body parts 2 and 3 after firing are treated with WET-N ２ The re-oxidation treatment is carried out in an atmosphere. The temperature for the re-oxidation treatment may be, for example, around 800 to 1100°C, or around 800 to 1000°C. The equilibrium partial pressure of oxygen is, for example, 10 －１２ ~10 －８ It can be around atm. The equilibrium partial pressure of oxygen is 10 －１２ If the oxygen equilibrium partial pressure is above atm, the dielectric layer 5 is sufficiently reoxidized, which can result in less insulation degradation of the laminate 2 and a reduction in the capacitance of the multilayer ceramic capacitor 1. －８ When the pressure is below atm, oxidation of the internal electrodes is reduced. The equilibrium partial pressure of oxygen is 10. －１２ ~10 －８ By setting the capacitance to approximately atm, capacitance and insulation resistance can be ensured without oxidizing the internal electrodes.

[0084] <Polishing and Formation of External Electrodes> Next, the main body portions 2 and 3 after the re-oxidation treatment are subjected to barrel polishing to sufficiently expose the internal electrode layer 6 on the end faces 8a and 8b, and to remove burrs from the main body portions 2 and 3, thereby obtaining the main body portions 2 and 3 as shown in Figure 2. By forming external electrodes 4a and 4b on the obtained main body portions 2 and 3, the multilayer ceramic capacitor 1 can be manufactured. Note that the external electrodes 4a and 4b may also be formed by applying a conductive paste that will become the external electrodes 4a and 4b to the unfired main body portions 2 and 3, and firing the main body portions 2 and 3 and the external electrodes 4a and 4b simultaneously.

[0085] The above describes an example in which the main body portions 2 and 3 are obtained by cutting the master laminate 15, but the method of manufacturing the main body portions 2 and 3 is not limited to this. The main body portions 2 and 3 may be manufactured, for example, by cutting the master laminate 15 to manufacture the laminate 2, and then forming the side margin portions 3 on the sides 9a and 9b of the laminate 2. When the laminate 2 is manufactured in this way, the electrode pattern of the pattern sheet 14 may differ from the electrode pattern shown in Figure 4. The side margin portions 3 may be formed, for example, by molding a ceramic green sheet for the side margin portions (hereinafter also referred to as the green sheet for the side margin portions) using a ceramic slurry similar to the ceramic slurry used to mold the green sheet 13, and then pressing the green sheet for the side margin portions against the sides 9a and 9b. In order to increase the adhesion of the green sheet for the side margin portions to the sides 9a and 9b, at least one of the laminate 2 and the green sheet for the side margin portions may be heated when pressing the green sheet for the side margin portions against the sides 9a and 9b. Alternatively, the green sheet for the side margin may be made tacky, and the green sheet for the side margin may be bonded to the sides 9a and 9b using an adhesive that does not affect the characteristics of the multilayer ceramic capacitor 1. The side margin 3 may be formed by applying the ceramic slurry prepared for molding the green sheet for the side margin to the sides 9a and 9b and drying it.

[0086] [Multilayer ceramic capacitor according to the second embodiment] The multilayer ceramic capacitor according to the second embodiment of this disclosure includes a laminate having alternately stacked dielectric layers and internal electrode layers, wherein the dielectric layers include crystalline particles having a perovskite structure with A sites and B sites, and the internal electrode layers are fired products of the conductive paste described above. The structure of the multilayer ceramic capacitor according to the second embodiment, the area ratio (%) occupied by metal element (2) in the internal electrode layer, the area ratio (%) occupied by metal element (1) in the internal electrode layer, the dielectric layer, external electrodes, cover layer, dimensions, etc., are the same as those of the multilayer ceramic capacitor according to the first embodiment described above. Furthermore, the manufacturing method of the multilayer ceramic capacitor according to the second embodiment is the same as that of the multilayer ceramic capacitor according to the first embodiment.

[0087] The present disclosure will now be described in detail by examples, but the present disclosure is not limited in any way by these examples.

[0088] <Raw Materials, etc.> The following were used as raw materials, etc.: (Dielectric powder) ・BaTiO ３ , D ５０ 80nm (conductive powder) ・Ni metal, D ５０ 200 nm (additive) ・BaCO ３ , D ５０ 50 nm ・Dy ２ O ３ , D ５０ 100nm ・CaCO ３ , D ５０ 100 nm

[0089] (Organic Solvents) Solvent 1: Ethyl alcohol Solvent 2: Toluene Solvent 3: Dihydroterpineol-based solvent

[0090] <Measurement and Evaluation Methods> In addition, each physical property was measured and evaluated as follows.

[0091] (Thickness of the internal electrode layer) A cross-section of the multilayer ceramic capacitor in the thickness direction (a cross-section parallel to the thickness direction (stack direction) of the multilayer ceramic capacitor) was imaged using a SEM. A binarized image was obtained using image analysis software from the backscattered electron image acquired by the SEM. The sum of the areas of the internal electrode layers present in the entire region of the binarized image and the sum of the lengths of the internal electrode layers were calculated, and the thickness of the internal electrode layer was calculated using the following formula: Thickness of the internal electrode layer (μm) = Sum of the areas of the internal electrode layers (μm) ２ ) / Total length of internal electrode layers (μm)

[0092] (Effective T-dimension) The effective T-dimension was measured for each of the following: the main body before firing, the main body after firing at 800°C, and the multilayer ceramic capacitor obtained after firing at 1100°C. Specifically, the various main body parts were polished, the internal cross-section was examined, and the effective T-dimension was measured using a microscope. Note that "effective T-dimension" refers to the distance from the surface on the side of the electrode pattern (electrode layer) closest to one surface in the thickness direction of the main body or multilayer ceramic capacitor, to the surface on the side of the electrode pattern (electrode layer) closest to the other surface in the thickness direction of the main body or multilayer ceramic capacitor.

[0093] (Area ratio (%) of metal element (2), metal element (2-1), and metal element (1) in the internal electrode layer) A cross-section in the thickness direction of a multilayer ceramic capacitor was imaged using a SEM. A binarized image was obtained using image analysis software from the backscattered electron image acquired by the SEM. The area of ​​the internal electrode layer present in the entire region of the binarized image and the area occupied by metal element (2), metal element (2-1), and metal element (1) within the internal electrode layer were calculated. The area ratio (%) of metal element (2), metal element (2-1), and metal element (1) in the internal electrode layer was calculated using the following formulas: Area ratio = (Area occupied by metal element (2)) / (Area of ​​internal electrode layer) × 100 Area ratio = (Area occupied by metal element (2-1)) / (Area of ​​internal electrode layer) × 100 Area ratio = (Area occupied by metal element (1)) / (Area of ​​internal electrode layer) × 100

[0094] (Qualitative analysis of elements in the internal electrode layer) The qualitative analysis of elements in the internal electrode layer was performed as follows: Elemental analysis was performed using SEM-EDS on the portion occupied by the metal element (2) observed by SEM to qualitatively determine the elements in the internal electrode layer.

[0095] (A / B ratio in the central part of the dielectric layer) In laser ICP analysis, the central part of the dielectric layer was irradiated with a laser, and mass spectrometry was performed using ICP-MS. By converting the mass spectrometry results to a molar ratio, the ratio of A sites to B sites of dielectric particles in the central part of the dielectric layer (A / B ratio (central part)) was calculated.

[0096] (A / B ratio at the dielectric layer interface) In TEM-EDS analysis, a laser was irradiated at a position 1 / 8 the thickness of the dielectric layer from the interface between the dielectric layer and the internal electrode layer, and mass spectrometry was performed using ICP-MS. By converting the results of this mass spectrometry to a molar ratio, the ratio of the A-site to the B-site of dielectric particles at the first interface of the dielectric layer (A / B ratio (interface)) was calculated. In addition, in TEM-EDS analysis, a laser was irradiated at a position 7 / 8 the thickness of the dielectric layer from the interface between the dielectric layer and the internal electrode layer, and mass spectrometry was performed using ICP-MS. By converting the results of this mass spectrometry to a molar ratio, the ratio of the A-site to the B-site of dielectric particles at the second interface of the dielectric layer (A / B ratio (interface)) was calculated. The average value of the ratio at the first interface (A / B ratio (interface)) and the ratio at the second interface (A / B ratio (interface)) was defined as the ratio at the interface of the dielectric layer (A / B ratio (interface)).

[0097] (Continuity) A cross-sectional image of the multilayer ceramic capacitor in the thickness direction was captured using a scanning electron microscope (SEM). Based on this SEM image, the length of the internal electrode layer and the sum of the lengths of the uncut portions of the internal electrode layer were determined, and the continuity of the internal electrode was calculated using the following formula: Continuity of internal electrode (%) = (sum of lengths of the uncut portions of the internal electrode layer) / (length of the internal electrode layer) × 100

[0098] (Capacitance) The capacitance of the obtained multilayer ceramic capacitors was measured. The measurement conditions were an ambient temperature of 20°C, a frequency of 1.0 kHz, and an applied voltage of 0.5 Vrms. Capacitance was measured using an LCR meter. For each of the examples and comparative examples, 20 multilayer ceramic capacitors were fabricated, and the arithmetic mean of their capacitances was taken as the capacitance (nF) of each example and comparative example sample.

[0099] (Mean Time to Failure (MTTF)) The obtained multilayer ceramic capacitors were subjected to a Highly Accelerated Life Test (HALT), and the Mean Time to Failure (MTTF) was measured. The test conditions were an ambient temperature of 125°C and an applied voltage (DC) of 10V. For each of the examples and comparative examples, 100 multilayer ceramic capacitors were fabricated, and the failure time at which the failure rate of the failed multilayer ceramic capacitors reached 50% was defined as MTF (hr).

[0100] [Example 1] (Manufacturing of ceramic green sheet) Dielectric powder (BaTiO ３ A ceramic slurry (solid content concentration: 20% by mass) was prepared by stirring and mixing 100 parts by mass of powder, 10 parts by mass of binder resin (butyral-based resin), and 400 parts by mass of organic solvent (a mixture of ethyl alcohol and toluene (mass ratio 1:1)).

[0101] Next, a ceramic green sheet with an average thickness of 0.5 μm was formed using the ceramic slurry by the doctor blade method.

[0102] (Manufacturing of conductive paste) A first slurry was prepared by blending an additive containing the type of metal element (2) shown in Table 1, a dispersant, and an organic solvent in the amounts shown in Table 1. A second slurry was prepared by blending the type of conductive powder, dispersant, binder resin, and organic solvent shown in Table 1 in the amounts shown in Table 1. Then, the first slurry and the second slurry were mixed to prepare a conductive paste with the composition shown in Table 1.

[0103] (Manufacture of multilayer ceramic capacitor) Using the obtained conductive paste, an electrode pattern serving as an internal electrode layer was printed on the main surface of the obtained green sheet in the areal density shown in Table 1 to form a pattern sheet. Next, 40 green sheets were laminated to form a base for the cover layer, and 300 of the obtained pattern sheets were laminated thereon. Then, 40 green sheets were again stacked to fabricate a mother laminate. The mother laminate was cut using a die cutting machine to fabricate a plurality of main body parts. For the main body parts, the effective T dimension was measured and taken as the effective T dimension before firing. Next, the main body parts were subjected to a degreasing treatment. For the main body parts after firing at 800 °C, the effective T dimension was measured. The measurement results of the effective T dimension before firing and after firing at 800 °C are shown in Table 1 and FIG. 10. The degreased main body parts were ２ -N ２ in a mixed gas of (H ２ : N ２ = 1:99 (volume ratio)) atmosphere and subjected to reduction firing. The firing temperature was 1100 °C, the heating rate was 3000 °C / hr, and the holding time at 1100 °C was 5 min. For the main body parts after firing at 1100 °C, the effective T dimension was measured. The results are shown in Table 1 and FIG. 10. The fired main body parts were subjected to a reoxidation treatment in a WET-N ２ atmosphere. The reoxidation treatment temperature was 1000 °C, the heating rate was 300 °C / hr, and the holding time at 1000 °C was 5 hr. The main body parts subjected to the reoxidation treatment were barrel polished, and an external electrode was formed on the polished main body parts to fabricate a multilayer ceramic capacitor.

[0104] [Examples 2-16 and Comparative Examples 1-4] Multilayer ceramic capacitors were fabricated in the same manner as in Example 1, except that a conductive paste was obtained by blending the components shown in Table 1 with 100 parts by mass of the Ni powder shown in Table 1 in the amounts shown in Table 1. The obtained multilayer ceramic capacitors were evaluated as described above. The results are shown in Table 1. Figure 8 is an SEM image of the cross-section of the multilayer ceramic capacitor of Example 6, and Figure 9 is a chart showing the results of elemental analysis by SEM-EDS elemental analysis at the locations indicated by arrows in Figure 8. Figure 10 is a graph showing the rate of change of the effective T dimension of the main body in Examples 6, 13, 15 and Comparative Example 2, and Figures 11-14 are SEM images of the cross-section in the stacking direction of the multilayer ceramic capacitors of Examples 6, 13, 15 and Comparative Example 2, respectively.

[0105]

[0106] As is clear from Table 1, the multilayer ceramic capacitors of Examples 1 to 16 (especially the multilayer ceramic capacitors of Examples 2 to 16) have high continuity of the internal electrode layer. Furthermore, the multilayer ceramic capacitors of Examples 3 to 9 have high continuity of the internal electrode layer, large capacitance, and long MTTF.

[0107] The multilayer ceramic capacitors of this disclosure have high continuity of the internal electrode layers, high capacitance, and long MTTF. Therefore, they are suitable for applications where these characteristics are required.

[0108] 1 Multilayer ceramic capacitor 2 Laminate 21 Cover layer 3 Side margin 3a Outer surface 4a First external electrode 4b Second external electrode 41 First layer (underlayment) 42 Second layer (outer layer) 5 Dielectric layer 6 Internal electrode layer 7a First surface 7b Second surface 8a First end surface 8b Second end surface 9a First side surface 9b Second side surface 13 Ceramic green sheet 14 Pattern sheet 15 Master laminate 16 Virtual dividing line

Claims

1. A multilayer ceramic capacitor comprising a laminate having alternately stacked dielectric layers and internal electrode layers, wherein the dielectric layers comprise crystalline particles having a perovskite structure with A-sites and B-sites, the internal electrode layers comprise a main component which is a metal composed of metal element (1) and a secondary component which comprises metal element (2), the metal element (2) comprises metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y and rare earth elements, and the total amount (moles) of metal element (2-1) is greater than the content (moles) of each metal element other than metal element (2-1) in the metal element (2), and less than the content (moles) of metal element (1).

2. The multilayer ceramic capacitor according to claim 1, wherein the metal element (2-1) is at least one selected from the group consisting of Ba, Ca, and Sr.

3. The multilayer ceramic capacitor according to claim 1 or 2, wherein the content of the metal element (2-1) in the metal element (2) is 100 mol%.

4. In a cross-section in the thickness direction, the area ratio occupied by the metal element (2-1) in the internal electrode layer is less than 15%, according to any one of claims 1 to 3.

5. In a cross-section in the thickness direction, the area ratio occupied by the metal element (2-1) in the internal electrode layer is 0.03 to 4.51%, according to any one of claims 1 to 3.

6. The multilayer ceramic capacitor according to any one of claims 1 to 3, wherein the area ratio occupied by the metal element (2-1) in the internal electrode layer in a cross-section in the thickness direction is 0.05 to 0.75%.

7. The multilayer ceramic capacitor according to any one of claims 1 to 6, wherein the ratio of A sites to B sites of perovskite structure crystal particles in the central part of the dielectric layer (A / B ratio (central part)) is smaller than the ratio of A sites to B sites of perovskite structure crystal particles in the interface of the dielectric layer located between the central part and the internal electrode layer (A / B ratio (interface)).

8. The multilayer ceramic capacitor according to any one of claims 1 to 7, wherein the laminate has a first main surface and a second main surface facing each other in the lamination direction, and at least one of the first main surface and the second main surface is a curved surface that curves in a concave shape.

9. A conductive paste comprising conductive powder, an additive containing a metal element (2), a dispersant, a binder resin, and an organic solvent, wherein the conductive powder is a metal powder composed of a metal element (1), the metal element (2) comprises a metal element (2-1) which is at least one selected from the group consisting of Ba, Ca, Sr, Y, and rare earth elements, and the total amount (moles) of the metal element (2-1) is greater than the content (moles) of each metal element other than the metal element (2-1) in the metal element (2-1), and less than the content (moles) of the metal element (1).

10. The conductive paste according to claim 9, wherein the metal element (2-1) is at least one selected from the group consisting of Ba, Ca, and Sr.

11. The conductive paste according to claim 9 or 10, wherein the content of the metal element (2-1) in the metal element (2) is 100 mol%.

12. The conductive paste according to any one of claims 9 to 11, wherein the content of the metal element (2-1) per 100 mole parts of the metal element (1) is 0.006 to 2.975 mole parts.

13. The conductive paste according to any one of claims 9 to 11, wherein the content of the metal element (2-1) per 100 mole parts of the metal element (1) is 0.030 to 0.500 mole parts.

14. A multilayer ceramic capacitor comprising a laminate having alternately stacked dielectric layers and an internal electrode layer, wherein the dielectric layer comprises crystalline particles having a perovskite structure with A-sites and B-sites, and the internal electrode layer is a fired product of the conductive paste described in any one of claims 9 to 13.

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