Filtering material and method for manufacturing a multilayer ceramic capacitor using the same

Abstract

The present invention provides a filtration material which is capable of removing fine inorganic particles from an inorganic paste such as a ceramic slurry and an conductive paste, the inorganic paste being used during the production of a multilayer ceramic capacitor.　The present invention provides a filtration material for filtering an inorganic paste which contains first inorganic particles having a particle diameter of 20 nm to 300 nm, second inorganic particles having a particle diameter of less than 20 nm, an organic solvent, a binder and a dispersant; and a potential having a polarity reverse from the polarity of the first inorganic particles and the second inorganic particles is applied to this filtration material.

Description

[Technical Field]

[0001] The present invention relates to a filter material for filtering inorganic paste, particularly inorganic paste such as ceramic slurry for forming green sheets of multilayer ceramic capacitors and conductive paste for forming internal electrodes. [Background technology]

[0002] Conventionally, green sheets used in the manufacture of multilayer ceramic capacitors are produced by uniformly applying a ceramic slurry onto a carrier film. However, in order to maintain consistent electrical properties of the multilayer ceramic capacitor, the ceramic slurry is passed through a filter equipped with a filtering material to remove particles with particle sizes outside a predetermined range before being applied to the carrier film.

[0003] However, while conventional filter media can generally capture particles with a diameter of 0.2 μm or larger, it is difficult to capture fine particles smaller than primary particles. In the dispersion process using media to prepare ceramic slurries, fine particles with a diameter of less than 20 nm, known as chipping particles, are generated, and these fine particles are mixed directly into the ceramic slurries.

[0004] Due to their large specific surface area, microparticles mixed into ceramic slurries promote the grain growth of ceramic particles during firing, preventing the formation of dense sintered bodies and reducing the insulation resistance of multilayer ceramic capacitors, thereby reducing their reliability. Furthermore, if microparticles segregate within elements, there is a significant tendency for their electrical properties to deteriorate.

[0005] Furthermore, in the manufacture of multilayer ceramic capacitors, a conductive paste is used to form internal electrode layers, and in preparing the conductive paste, it is also important to regulate the particle size of inorganic particles such as metal particles within a predetermined range in order to maintain electrical properties.

[0006] Therefore, in order to improve the reliability of multilayer ceramic capacitors, there is a need to develop a filter material that can remove minute inorganic particles from inorganic pastes such as ceramic slurries and conductive pastes. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-131437 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a filter material capable of removing minute inorganic particles from inorganic pastes such as ceramic slurries and conductive pastes used in the manufacture of multilayer ceramic capacitors. [Means for solving the problem]

[0009] The present inventors discovered that fine inorganic particles can be effectively removed by using a filtering material to which a potential of opposite polarity to that of the inorganic particles contained in the inorganic paste is applied, and thus completed the present invention.

[0010] That is, the present invention provides a filtering material for filtering an inorganic paste containing first inorganic particles having a particle size of 20 nm or more and 300 nm or less, second inorganic particles having a particle size of less than 20 nm, an organic solvent, a binder, and a dispersant, the filtering material being given a potential of opposite polarity to the potentials of the first inorganic particles and the second inorganic particles. [Effects of the Invention]

[0011] The filter material of the present invention can remove fine particles from inorganic pastes such as ceramic slurries and conductive pastes used in the manufacture of multilayer ceramic capacitors, thereby suppressing a decrease in insulation resistance and improving the reliability of the multilayer ceramic capacitors. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an external view of a multilayer ceramic capacitor. [Figure 2] 2 is a cross-sectional view taken along the line AA of the multilayer ceramic capacitor shown in FIG. [Figure 3] FIG. 2 is an exploded perspective view schematically illustrating an example of an inner layer portion. [Figure 4] 1 is a graph showing changes in the logarithm of the insulation resistance value (Log IR) of a multilayer ceramic capacitor. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, as an embodiment of the present invention, the configuration of an inorganic paste to be filtered by the filtering material of the present invention, particularly a ceramic slurry for forming a green sheet of a multilayer ceramic capacitor or a conductive paste for forming an internal electrode layer, and the filtering material will be described.

[0014] Although a two-terminal multilayer ceramic capacitor is shown as an example of a multilayer ceramic capacitor manufactured using a ceramic slurry or conductive paste filtered through a filter material, the present invention is not limited to this. Furthermore, the drawings may be drawn in a simplified schematic form to explain the contents of the invention, and the dimensional ratios of the depicted components or between the components may not match those described in the specification. Furthermore, components described in the specification may be omitted from the drawings, or the number of components may be omitted.

[0015] (multilayer ceramic capacitors) 1 to 3 show the shape and structure of a multilayer ceramic capacitor 1. FIG. 1 is an external view of the multilayer ceramic capacitor 1. FIG. 2 is a cross-sectional view (LT cross-sectional view) of the multilayer ceramic capacitor 1 taken along line AA at the center of the width direction W shown in FIG. 1. FIG. 3 is a schematic diagram showing the structure of an inner layer portion 3. The structure of the multilayer ceramic capacitor 1 will be described using the stacking direction T, which is the direction in which the dielectric layers and internal electrode layers are stacked, a length direction L perpendicular to the stacking direction T, and a width direction W perpendicular to the stacking direction T and the length direction L. In the embodiment, the width direction W, the length direction L, and the stacking direction T are perpendicular to one another, but they do not necessarily have to be perpendicular to one another and may intersect one another.

[0016] The multilayer ceramic capacitor 1 includes a rectangular parallelepiped laminate 2. The laminate 2 includes an inner layer portion 3 and has a pair of first and second main surfaces TS1 and TS2 facing each other in a stacking direction T, a pair of first and second end surfaces LS1 and LS2 facing each other in a length direction L perpendicular to the stacking direction T, and a pair of first and second side surfaces WS1 and WS2 facing each other in a width direction W perpendicular to both the stacking direction T and the length direction L.

[0017] The dimensions of the multilayer ceramic capacitor 1 are not particularly limited, but for example, the height direction T dimension can be approximately 0.1 mm to 2.5 mm, the length direction L dimension can be approximately 0.1 mm to 3.2 mm, and the width direction W dimension can be approximately 0.1 mm to 2.5 mm.

[0018] On the surface of the laminate 2, a first external electrode 4a and a second external electrode 4b are formed.

[0019] The first external electrode 4a is formed on a first end surface LS1 of the laminate 2. The first external electrode 4a is formed in a cap shape, and its edge portion extends from the first end surface LS1 of the laminate 2 to the first main surface TS1, the second main surface TS2, the first side surface WS1, and the second side surface WS2.

[0020] The second external electrode 4b is formed on the second end surface LS2 of the laminate 2. The second external electrode 4b is formed in a cap shape, and its edge portion extends from the second end surface LS2 of the laminate 2 to the first main surface TS1, the second main surface TS2, the first side surface WS1, and the second side surface WS2.

[0021] In the multilayer ceramic capacitor 1, the first internal electrode layer 6a extended to the first end face LS1 of the laminate 2 is connected to the first external electrode 4a, and the second internal electrode layer 6b extended to the second end face LS2 of the laminate 2 is connected to the second external electrode 4b.

[0022] The external electrode 4 may have a structure including, for example, a base electrode layer and a plating layer disposed on the base electrode layer.

[0023] The base electrode layer is formed by applying a conductive paste containing glass and metal to the laminate and baking the paste. The baking may be performed simultaneously with or after the firing of the laminate.

[0024] The plating layer disposed on the base electrode layer includes at least one of metals such as Cu, Ni, Ag, Pd, and Au, or an alloy of Ag and Pd. The plating layer may be a single layer or multiple layers. For example, the plating layer may have a two-layer structure of a Ni plating layer and a Sn plating layer.

[0025] The internal layer portion 3 is composed of a plurality of dielectric layers 5 and a plurality of internal electrode layers 6 stacked one on top of the other. The internal electrode layers 6 are composed of a first internal electrode layer 6a and a second internal electrode layer 6b. The first internal electrode layer 6a and the second internal electrode layer 6b are disposed on the dielectric layers 5a and 5b, respectively.

[0026] The internal electrode layers 6 extend in the longitudinal direction L and have a rectangular shape in a plan view. The first internal electrode layer 6a is extended to a first end face LS1 of the laminate 2, and the second internal electrode layer 6b is extended to a second end face LS2 of the laminate 2.

[0027] Any material may be used for the dielectric layer 5, but for example, ceramic powder containing BaTiO3 as the main component may be used. Also, instead of BaTiO3, ceramic powder containing other materials as the main component, such as CaTiO3 or SrTiO3, may be used.

[0028] The thickness of the dielectric layer 5 is not particularly limited, but can be, for example, about 0.3 μm to 2.0 μm in the effective region for forming capacitance formed by the first internal electrode layer 6a and the second internal electrode layer 6b.

[0029] The number of dielectric layers 5 is not particularly limited, but can be, for example, 1 to 6000 layers in the effective area for forming capacitance formed by the first internal electrode layers 6a and the second internal electrode layers 6b.

[0030] On both the top and bottom of the internal layer portion 3, external layer portions 7 are provided, which are composed only of dielectric layers 5 and have no internal electrode layers 6. The thickness of the external layer portions 7 is not limited, but may be, for example, 15 μm to 150 μm. The thickness of the dielectric layer in the external layer portion 7 may be greater than the thickness of the dielectric layer in the effective region for capacitance formation where the internal electrode layers 6 are formed. The material of the dielectric layer in the external layer portion may be different from the material of the dielectric layer in the internal layer portion.

[0031] FIG. 3 shows the inner layer portion 3 broken down into individual dielectric layers 5 in the stacking direction T.

[0032] The internal electrode layers 6 are formed by sintering a conductive paste containing metal powder as a conductor, an organic solvent, a binder, and a dispersant on the dielectric layers. The internal electrode layers 6 and the dielectric layers 5 are alternately stacked to form the internal layer portion 3. The internal electrode layers 6 are composed of a first internal electrode layer 6a and a second internal electrode layer 6b, and the first internal electrode layer 6a and the second internal electrode layer 6b are arranged on the dielectric layers 5a and 5b, respectively.

[0033] Metals such as Cu, Ni, Ag, Au, and Pt can be used for the internal electrode layers 6. These metals may also be compounds containing these metal elements or alloys with other metals.

[0034] The thickness of the internal electrode layer 6 is not particularly limited, but can be, for example, about 0.3 μm to 1.5 μm.

[0035] (Manufacturing method of multilayer ceramic capacitors) An example of a method for manufacturing the multilayer ceramic capacitor 1 will be described below.

[0036] A ceramic slurry is prepared for forming the dielectric layers 5 of the multilayer ceramic capacitor 1. A perovskite compound containing Ba and Ti can be used as the ceramic powder that constitutes the ceramic slurry.

[0037] General formula A m The molar ratio A / B of A to B in the perovskite compound represented by BO3 does not need to be a stoichiometric composition, but is preferably 0.98 or more and 1.02 or less.

[0038] As the Ba source, a Ba compound such as BaCO3 can be used, and as the Ti source, a Ti compound such as TiO2 can be used.

[0039] Other perovskite compounds include CaTiO3, SrTiO3, etc., and any one of these can be selected or used in combination.

[0040] There is no particular restriction on the form of the various compounds, and they are not limited to oxide powders and carbonate powders, but may also be chloride powders, sols, metal organic compounds, and the like.

[0041] There are no particular limitations on the method for producing the perovskite compound, and known methods such as a solid phase method, a liquid phase method, a hydrothermal synthesis method, and a hydrolysis method can be used.

[0042] An organic solvent, a binder, and a dispersant are added to the ceramic powder obtained as described above, and the mixture is mixed using a ball mill or the like to prepare a ceramic slurry.

[0043] The ceramic slurry can be prepared by kneading ceramic powder with an organic vehicle, which is a binder dissolved in an organic solvent.

[0044] The binder used in the organic vehicle is not particularly limited and may be appropriately selected from various common binders such as ethyl cellulose, polyvinyl butyral, etc. The organic solvent used in the organic vehicle is also not particularly limited and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, toluene, etc.

[0045] The dispersibility of the ceramic powder can be improved by adding a dispersant. The dispersant is not particularly limited and may be any of anionic, cationic, or nonionic dispersants, such as polyacrylic acid or its ammonium salt, polyacrylic acid ester copolymer, polyethylene oxide, polyoxyethylene alkyl amyl ether, fatty acid diethanolamide, polyethylene imine, and copolymers of polyoxypropylene monoallyl monobutyl ether and maleic anhydride.

[0046] The prepared ceramic slurry is filtered using a filter material, the details of which will be described later.

[0047] A conductive paste for forming the internal electrode layers of the multilayer ceramic capacitor is prepared.

[0048] The conductive paste for the internal electrode layers contains inorganic particles made of metals such as Cu, Ni, Ag, Au, and Pt or compounds containing these metal elements, an organic solvent, a binder, and a dispersant.

[0049] The conductive paste for the internal electrode layers is prepared by kneading inorganic particles containing the above-mentioned metals and the like with the above-mentioned organic vehicle. The conductive paste may also contain a co-material. The co-material is not particularly limited, but preferably has the same composition as the main component forming the dielectric layer.

[0050] The paste for the external electrodes may be prepared in the same manner as the conductive paste for the internal electrode layers described above.

[0051] The amount of organic vehicle contained in each of the above pastes is not particularly limited, and may be a normal content, for example, about 1 to 5 wt % for binder and about 10 to 50 wt % for solvent. Furthermore, each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, etc., as needed. The total content of these is preferably 10 wt % or less.

[0052] The prepared conductive paste is filtered using a filter, the details of which will be described later.

[0053] Methods for laminating the dielectric layers and internal electrode layers include printing and sheet methods.

[0054] In the printing method, ceramic slurry and conductive paste are printed and laminated on a substrate such as PET, and after cutting into a predetermined shape, the substrate is peeled off to form a green chip.

[0055] In the sheet method, a green sheet is formed using ceramic slurry, a conductive paste is printed on the green sheet to form an internal electrode layer pattern, and then these are laminated to form a green chip.

[0056] Before firing, the green chip is subjected to a binder removal treatment. The conditions for the binder removal treatment are a temperature rise rate of preferably 5 to 300°C / hour, a holding temperature of preferably 180 to 400°C, and a temperature holding time of preferably 0.5 to 24 hours. The binder removal atmosphere is air or a reducing atmosphere.

[0057] After the binder removal treatment, the green chip is fired. The temperature rise rate during firing is preferably 100 to 500°C / hour. The holding temperature during firing is preferably 1300°C or less, more preferably 1150 to 1280°C, and the holding time is preferably 0.5 to 8 hours, more preferably 2 to 3 hours. If the holding temperature is below the above range, densification will be insufficient, and if it exceeds this range, discontinuities will occur due to abnormal sintering of the internal electrode layers, deterioration of the capacitance-temperature characteristics will occur due to diffusion of the components constituting the internal electrode layers, and reduction of the dielectric ceramic composition will be likely to occur.

[0058] The firing atmosphere is preferably a reducing atmosphere, for example, a humidified mixed gas of N2 and H2 can be used.

[0059] The oxygen partial pressure during firing can be determined appropriately depending on the type of metal in the conductive paste. When using base metals such as Ni or Ni alloys, the oxygen partial pressure in the firing atmosphere should be 10 -14 ~10 -10 MPa. If the oxygen partial pressure is less than the above range, the conductive material of the internal electrode layers may sinter abnormally and be broken. If the oxygen partial pressure exceeds the above range, the internal electrode layers tend to oxidize. The temperature-lowering rate is preferably 50 to 500°C / hour.

[0060] After firing in a reducing atmosphere, the laminate is preferably annealed, which is a treatment to reoxidize the dielectric layers, thereby extending the life of the insulation resistance and therefore improving reliability.

[0061] The oxygen partial pressure in the atmosphere during annealing is 10 -9 ~10 -5 If the oxygen partial pressure is below the above range, it is difficult to re-oxidize the dielectric layers, and if it exceeds the above range, oxidation of the internal electrode layers tends to progress.

[0062] The holding temperature during annealing is preferably 1100°C or less, particularly 1000 to 1100°C. If the holding temperature is below the above range, the dielectric layer will not be sufficiently oxidized, resulting in a low IR and a shortened insulation resistance life. On the other hand, if the holding temperature exceeds the above range, not only will the internal electrode layers be oxidized and the capacity will decrease, but the internal electrode layers will also react with the dielectric layers, which will likely result in a deterioration in the capacitance-temperature characteristic, a decrease in insulation resistance, and a shortened insulation resistance life. Note that annealing may consist of only a temperature increase process and a temperature decrease process. In this case, the holding temperature is synonymous with the maximum temperature, and there is no temperature holding time.

[0063] Other annealing conditions include a temperature holding time of preferably 0 to 20 hours, more preferably 2 to 4 hours, and a temperature drop rate of preferably 50 to 500°C / hour, more preferably 100 to 300°C / hour. The annealing atmosphere is preferably, for example, humidified N2 gas.

[0064] In the above-mentioned binder removal treatment, firing and annealing, N2 gas or mixed gas can be humidified using, for example, a wetter, etc. In this case, the water temperature is preferably about 5 to 75°C.

[0065] The binder removal treatment, firing, and annealing may be carried out consecutively or independently.

[0066] The laminate obtained by the above steps is subjected to end surface polishing, for example, by barrel polishing or sandblasting, and then external electrode paste is applied and fired to form the external electrodes 4. Then, if necessary, a coating layer is formed on the surface of the external electrodes 4 by plating or the like.

[0067] (filtration of inorganic paste) The ceramic slurry and inorganic conductive paste used in the manufacture of multilayer ceramic capacitors generate tiny particles with a diameter of less than 20 nm called chipping particles during the dispersion process using media in a ball mill.Due to their large specific surface area, these tiny particles promote the grain growth of inorganic particles during firing and become a factor that inhibits the formation of a dense sintered body, so they must be removed using a filter equipped with a specified filtering material.

[0068] The inorganic paste contains inorganic particles, an organic solvent, a binder, and a dispersant, and the inorganic particles include first inorganic particles having a particle size of 20 nm or more and 300 nm or less, and second inorganic particles having a particle size of less than 20 nm.

[0069] The viscosity of the inorganic paste is preferably 15 mPa·s or more and 45 mPa·s or less. If the viscosity is less than 15 mPa·s, the slurry concentration will be low in the filtration process, which will take a long time to pass the required amount of raw material, and if the viscosity is more than 45 mPa·s, the liquid passing pressure will be too high, which will cause the filter to become clogged.

[0070] The materials of the filter material are listed below. The filter material can be made of fibers or porous materials made of these materials.

[0071] Synthetic resin Polyolefin resins, polyester resins, polyamide resins, fluororesins, etc., specifically, high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene, polypropylene, polypropylene random copolymer, polyester (polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc.), polyamide (nylon-6, nylon-66, etc.), polytetrafluoroethylene (PTFE), polyperfluoroalkoxyalkane (PFA), polyvinylidene fluoride (PVDF), polyvinyl chloride, polyimide, polyacrylonitrile, polycarbonate, polystyrene, polyethersulfone, polysulfone, cellulose, etc.

[0072] ·Inorganic compounds Glass, silica, alumina, carbon, ceramic, etc.

[0073] ·metal Stainless steel, etc.

[0074] There are several methods for applying a positive or negative electrode potential to the filter material, as listed below.

[0075] When manufacturing the filtration material, materials with cationic or anionic groups are mixed in. -Fixing a material with cationic or anionic groups onto the filtering material by coating or immersion. -Reactive groups are introduced into the filtering material, and materials having cationic or anionic groups are reacted and immobilized. - Irradiating the filtering material with radiation or plasma, etc., to immobilize materials with cationic or anionic groups

[0076] The inorganic paste is filtered using a filter material that is given an electric potential of the opposite polarity to that of the inorganic particles contained in the inorganic paste, making it possible to capture microparticles smaller than primary particles that could not be captured by conventional filter materials.

[0077] The inorganic particles contained in the inorganic paste include first inorganic particles with a particle size of 20 nm to 300 nm and second inorganic particles with a particle size of less than 20 nm, and by using a filter material to which a potential of the opposite polarity to that of the first inorganic particles and the second inorganic particles is applied, the second inorganic particles are attracted to and captured by the filter material, thereby producing an inorganic paste containing the first inorganic particles.

[0078] The flow rate of the inorganic paste passing through the filter material is preferably 0.5 kg / min or more and 2.0 kg / min or less. By filtering at such a flow rate, the second inorganic particles can be efficiently captured by the filter material.

[0079] By removing the fine particles in this manner, it is possible to suppress the grain growth of the inorganic particles during firing, thereby suppressing the decrease in the insulation resistance of the multilayer ceramic capacitor and improving its reliability.

[0080] (Comparative test) To confirm the effectiveness of filtering inorganic paste, a comparative test was conducted using a filter material made of a fibrous body to which a potential of opposite polarity to that of the inorganic particles was applied, and a conventional filter material made of a fibrous body to which no potential was applied.

[0081] Ceramic slurry with a viscosity of 30 mPa·s was filtered through each filter at a flow rate of 1.0 kg / min, and then the physical properties of the multilayer ceramic capacitors manufactured using the ceramic slurry filtered through each filter were measured.

[0082] (insulation resistance) Thirty samples of each type were charged at room temperature by applying a DC voltage of 4 V between the external electrodes of the sample and holding the voltage for 60 seconds. After charging, the insulation resistance of each sample was measured and its logarithmic value, Log IR, was calculated. The results are shown in Table 1.

[0083] [Table 1]

[0084] As shown in Table 1, the variation (CV value) of the logarithm of the insulation resistance value (Log IR) for the sample using a filter material to which no potential was applied was 8.03, whereas the variation (CV value) of the logarithm of the insulation resistance value (Log IR) for the sample using a filter material to which a potential was applied was 3.60, confirming favorable results.

[0085] Next, the insulation resistance IR of each of the 72 samples was continuously measured at a temperature of 150°C and an applied voltage of 3.2V, and the change in the logarithmic value (Log IR) was calculated. The results are shown in Figure 4.

[0086] As shown in Figure 4, it was confirmed that the sample using a filter material to which a potential was applied showed a smaller decrease in the logarithm of the insulation resistance value (Log IR) over time than the sample using a filter material to which no potential was applied.

[0087] Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and can be embodied in various forms without departing from the gist of the present invention. [Explanation of symbols]

[0088] 1. Multilayer ceramic capacitors 2. Laminate 3. Inner layer 4 External electrode 4a 1st external electrode 4b 2nd external electrode 5 Dielectric Layer 5a Dielectric layer 5b Dielectric layer 6 Internal electrode layer 6a 1st internal electrode layer 6b Second internal electrode layer 7 Outer layer TS1 First main surface TS2 Second principal surface WS1 1st aspect WS2 Second Side LS1 1st end face LS2 2nd end face

Claims

1. A filter material for filtering a ceramic slurry containing first inorganic particles having a particle size of 20 nm or more and 300 nm or less, second inorganic particles having a particle size of less than 20 nm, an organic solvent, a binder, and a dispersant, wherein a potential of opposite polarity to the potentials of the first inorganic particles and the second inorganic particles is applied to the filter material, thereby attracting and capturing the second inorganic particles.

2. A filter material for filtering a conductive paste containing first inorganic particles having a particle size of 20 nm or more and 300 nm or less, second inorganic particles having a particle size of less than 20 nm, an organic solvent, a binder, and a dispersant, wherein a potential of opposite polarity to the potentials of the first inorganic particles and the second inorganic particles is applied to the filter material, thereby capturing the second inorganic particles.

3. A filter material according to claim 1, wherein the ceramic slurry is a ceramic slurry for forming a green sheet.

4. A filter material according to claim 2, wherein the conductive paste is a conductive paste for forming an internal electrode pattern on a green sheet.

5. 2. The filtering medium according to claim 1, wherein the first inorganic particles and the second inorganic particles contain at least one element selected from the group consisting of Ba, Ti, Ca, and Sr.

6. The filter medium according to claim 2 , wherein the first inorganic particles and the second inorganic particles contain at least one element selected from the group consisting of Cu, Ni, Ag, Au, and Pt.

7. 6. The filter medium according to claim 1, wherein the ceramic slurry has a viscosity of 15 mPa·s or more and 45 mPa·s or less.

8. 7. The filtering material according to claim 2, wherein the conductive paste has a viscosity of 15 mPa·s or more and 45 mPa·s or less.

9. A method for manufacturing a multilayer ceramic capacitor, comprising: a step of preparing an inorganic paste containing first inorganic particles having a particle size of 20 nm or more and 300 nm or less, second inorganic particles having a particle size of less than 20 nm, an organic solvent, a binder, and a dispersant; and a step of filtering the inorganic paste using a filtering material that is applied with a potential of opposite polarity to the potentials of the first inorganic particles and the second inorganic particles and that attracts and captures the second inorganic particles.

10. 10. The method for producing a multilayer ceramic capacitor according to claim 9, wherein the first inorganic particles and the second inorganic particles contain at least one element selected from the group consisting of Ba, Ti, Ca, and Sr.

11. 10. The method for producing a multilayer ceramic capacitor according to claim 9, wherein the first inorganic particles and the second inorganic particles contain at least one element selected from the group consisting of Cu, Ni, Ag, Au, and Pt.

12. The method for producing a multilayer ceramic capacitor according to claim 9 , wherein the inorganic paste is filtered at a flow rate of 0.5 kg / min or more and 2.0 kg / min or less.

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