WO2025047707A1 - 積層セラミックコンデンサ - Google Patents

積層セラミックコンデンサ Download PDF

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Publication number
WO2025047707A1
WO2025047707A1 PCT/JP2024/030406 JP2024030406W WO2025047707A1 WO 2025047707 A1 WO2025047707 A1 WO 2025047707A1 JP 2024030406 W JP2024030406 W JP 2024030406W WO 2025047707 A1 WO2025047707 A1 WO 2025047707A1
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dielectric
ceramic
outer layer
internal electrode
layer portion
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English (en)
French (fr)
Japanese (ja)
Inventor
健之 上野
幸祐 浦谷
信弥 磯田
博之 和田
敬史 浅野
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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Priority to JP2025543486A priority Critical patent/JPWO2025047707A1/ja
Priority to CN202480055066.2A priority patent/CN121729752A/zh
Priority to KR1020267003416A priority patent/KR20260027350A/ko
Publication of WO2025047707A1 publication Critical patent/WO2025047707A1/ja
Priority to US19/295,836 priority patent/US20250364186A1/en
Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/30—Stacked capacitors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/005—Electrodes
    • H01G4/012—Form of non-self-supporting electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • H01G4/1209—Ceramic dielectrics characterised by the ceramic dielectric material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • H01G4/1209—Ceramic dielectrics characterised by the ceramic dielectric material
    • H01G4/1218—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates
    • H01G4/1227—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates based on alkaline earth titanates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/224—Housing; Encapsulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/228—Terminals
    • H01G4/232—Terminals electrically connecting two or more layers of a stacked or rolled capacitor

Definitions

  • the present invention relates to a multilayer ceramic capacitor.
  • Multilayer ceramic capacitors have thin, high-permittivity dielectric layers. Therefore, they have a large capacitance despite their small size.
  • Multilayer ceramic capacitors using various materials are known, but those using ceramic dielectrics such as barium titanate (BaTiO 3 ) for the dielectric layers and base metals such as nickel (Ni) for the internal electrode layers are widely used because they are inexpensive and exhibit high performance.
  • a multilayer ceramic capacitor comprises an inner layer portion in which dielectric layers formed of ceramic dielectrics and internal electrode layers are alternately laminated, an outer layer portion covering the top and bottom of the inner layer portion, and a side margin portion covering the inner layer portion and the outer layer portion in the width direction.
  • the inner layer portion acts as a capacitance element.
  • the outer layer portion and the side margin portion are areas that do not include the internal electrode layers and are provided around the inner layer portion. It can be said that they act to protect the inner layer portion, which acts as a capacitance element, from the external environment.
  • the ceramic dielectric of a multilayer ceramic capacitor is produced by sintering a dielectric powder such as BaTiO3 powder.
  • the dielectric powder is synthesized by a method such as a solid-phase method, a hydrothermal method, a sol-gel method, an alkoxide method, a solvothermal method, or an oxalate method.
  • the hydrothermal method hydroothermal synthesis method
  • hydroxide is used as a raw material.
  • a Ba source such as barium hydroxide (Ba(OH) 2 )
  • a Ti source such as metatitanate (TiO(OH) 2 ) or titanium oxide (TiO 2 ) in high-temperature and high-pressure water
  • TiO(OH) 2 metatitanate
  • TiO 2 titanium oxide
  • the OH group contained in the hydroxide is released from the raw material during the heat treatment, which forms voids (intragranular voids) inside the particles that constitute the dielectric powder.
  • intragranular voids When a multilayer ceramic capacitor is manufactured using a dielectric powder having intragranular voids, the intragranular voids remain in the obtained capacitor.
  • intragranular voids are not formed.
  • Patent Document 1 discloses that hydrothermally synthesized dielectric powder is used in the dielectric layers of multilayer ceramic capacitors. Specifically, it discloses a method for producing a ceramic capacitor, which includes a process for producing a green sheet using a ceramic slurry containing a first ceramic powder synthesized by a hydrothermal method and a second ceramic powder synthesized by a method other than the hydrothermal method, and a process for firing the obtained green sheet (claim 5 of Patent Document 1). Patent Document 1 also describes that pores (vacancies) present in the ceramic particles relieve piezoelectric distortion, which leads to crack suppression ([0031] of Patent Document 1).
  • the inventors discovered that by controlling the ratio of intragranular voids in the inner layer, outer layer, and side margin of a multilayer ceramic capacitor so that these satisfy a predetermined relationship, it is possible to obtain a multilayer ceramic capacitor that is particularly excellent in terms of moisture resistance.
  • the present invention was completed based on these findings, and its objective is to provide a multilayer ceramic capacitor that is particularly excellent in terms of moisture resistance.
  • the present invention includes the following aspects.
  • the expression "-" includes both ends of the expression.
  • X-Y is synonymous with "X or more and Y or less.”
  • an inner layer portion in which first internal electrode layers and second internal electrode layers are alternately stacked with dielectric layers formed of ceramic dielectrics interposed therebetween, the inner layer portion having a first main surface which is a surface in a stacking direction, a second main surface which is a surface opposite to the first main surface, a first side surface which is a width direction surface perpendicular to the first main surface and the second main surface and from which the first internal electrode layers and the second internal electrode layers are drawn out, a second side surface which is a surface opposite to the first side surface and from which the first internal electrode layers and the second internal electrode layers are drawn out, a first end surface which is a length direction surface perpendicular to the first main surface, the second main surface, the first side surface, and the second side surface and from which the first internal electrode layers are drawn out, and a second end surface which is a surface opposite to the first end surface and from which the second internal electrode layers are drawn out; a first outer layer portion formed of a ceramic dielectric material
  • the present invention provides a multilayer ceramic capacitor that is particularly excellent in terms of moisture resistance.
  • FIG. 2 is a perspective view showing the outer shape of the multilayer ceramic capacitor.
  • 1 is a cross-sectional view that typically illustrates an internal structure of a multilayer ceramic capacitor.
  • 1 is a cross-sectional view that typically illustrates an internal structure of a multilayer ceramic capacitor.
  • the multilayer ceramic capacitor of this embodiment has an inner layer portion, a first outer layer portion, a second outer layer portion, a first side margin portion, a second side margin portion, and a pair of outer electrodes.
  • the inner layer portion is a region in which the first internal electrode layers and the second internal electrode layers are alternately laminated with a dielectric layer formed of a ceramic dielectric interposed therebetween.
  • the inner layer portion has a first main surface, a second main surface, a first side surface, a second side surface, a first end surface, and a second end surface.
  • the first main surface is a surface in the lamination direction of the dielectric layers, the first internal electrode layers, and the second electrode layers.
  • the second main surface is a surface opposite to the first main surface.
  • the first side surface is a surface in the width direction perpendicular to the first main surface and the second main surface.
  • the second side surface is a surface opposite to the first side surface.
  • the first end surface is a surface in the length direction perpendicular to the first main surface, the second main surface, the first side surface, and the second side surface, and is a surface from which the first internal electrode layer is drawn out.
  • the second end face is a face opposite to the first end face, and is a face from which the second internal electrode layer is drawn out.
  • the first external layer portion is formed of a ceramic dielectric and covers the first main surface from the stacking direction.
  • the second external layer portion is formed of a ceramic dielectric and covers the second main surface from the stacking direction.
  • the first side margin portion is formed of a ceramic dielectric and covers the internal layer portion, the first external layer portion, and the second external layer portion from one side in the width direction.
  • the second side margin portion is formed of a ceramic dielectric and covers the internal layer portion, the first external layer portion, and the second external layer portion from the other side in the width direction.
  • a pair of external electrodes is provided on the first end face and the second end face, and is connected to either the first internal electrode layer or the second internal electrode layer.
  • Each of the ceramic dielectrics constituting the internal layer portion, the first external layer portion, the second external layer portion, the first side margin portion, and the second side margin portion has a plurality of dielectric particles having voids therein.
  • the intragranular void ratio (N inner ) of the ceramic dielectric in the inner layer portion, the intragranular void ratio (N outer ) of the ceramic dielectric in the first outer layer portion and the second outer layer portion, and the intragranular void ratio (N side ) of the ceramic dielectric in the first side margin portion and the second side margin portion satisfy both of formula (1): N outer ⁇ N inner and formula (2): N side ⁇ N inner .
  • Figure 1 is a perspective view showing the external shape of a multilayer ceramic capacitor.
  • Figure 2 is a cross-section taken along line II-II of the multilayer ceramic capacitor shown in Figure 1
  • Figure 3 is a cross-section taken along line III-III of the multilayer ceramic capacitor shown in Figure 1.
  • the multilayer ceramic capacitor (100) comprises an element body (6) and a pair of external electrodes (8a, 8b) provided on both end faces (14a, 14b) of the element body (6).
  • the multilayer ceramic capacitor (100) and the element body (6) have an approximately rectangular parallelepiped shape.
  • An approximately rectangular parallelepiped includes not only rectangular parallelepipeds, but also rectangular parallelepipeds with rounded corners and/or edges.
  • the multilayer ceramic capacitor (100) and the element part (6) have a first outer main surface (10a) and a second outer main surface (10b) that face the thickness direction T, a first outer side surface (12a) and a second outer side surface (12b) that face the width direction W, and a first outer end surface (14a) and a second outer end surface (14b) that face the length direction L.
  • the thickness direction T is the direction in which the dielectric layers (2) and the internal electrode layers (4) included in the element part (6) are stacked.
  • the length direction L is perpendicular to the thickness direction T and is the direction in which the outer end surfaces (14a, 14b) face each other.
  • the width direction W is a direction perpendicular to the thickness direction T and the length direction L.
  • a surface including the thickness direction T and the width direction W is defined as a WT surface
  • a surface including the width direction W and the length direction L is defined as an LW surface
  • a surface including the length direction L and the thickness direction T is defined as an LT surface.
  • the body portion (6) is composed of an inner layer portion (16), a first outer layer portion (18a), a second outer layer portion (18b), a first side margin portion (20a), and a second side margin portion (20b).
  • the inner layer portion (16) is a region in which the internal electrode layers (4) are alternately stacked with the dielectric layers (2) interposed therebetween.
  • the dielectric layers (2) are made of a ceramic dielectric.
  • the internal electrode layers (4) are composed of a plurality of first internal electrode layers (4a) and a plurality of second internal electrode layers (4b).
  • the inner layer portion (16) has a first main surface, a second main surface, a first side surface, a second side surface, a first end surface, and a second end surface.
  • the first main surface is a surface perpendicular to the stacking direction of the dielectric layer (2) and the internal electrode layers (4a, 4b).
  • the second main surface is a surface (opposing surface) opposite the first main surface.
  • the first side surface is a surface perpendicular to the first main surface and the second main surface, that is, a surface perpendicular to the width direction W.
  • the second side surface is a surface (opposing surface) opposite the first side surface.
  • the first end surface is a surface perpendicular to the first main surface, the second main surface, the first side surface, and the second side surface, that is, a surface perpendicular to the length direction L.
  • the second end surface is a surface (opposing surface) opposite the first end surface.
  • the internal electrode layers (4a, 4b) are drawn out to the first side surface and the second side surface. In other words, the ends of the internal electrode layers are exposed on both the first side surface side and the second side surface side.
  • the first internal electrode layer (4a) is extended to the first end face, but the second internal electrode layer (4b) is not extended.
  • the second internal electrode layer (4b) is extended to the second end face, but the first internal electrode layer (4a) is not extended.
  • the first outer layer portion (18a) is a region that covers the first main surface of the inner layer portion (16) from the stacking direction (thickness direction T).
  • the second outer layer portion (18b) is a region that covers the second main surface of the inner layer portion (16) from the stacking direction.
  • the first side margin portion (20a) is a region that covers the inner layer portion (16), the first outer layer portion (18a), and the second outer layer portion (18b) from one side in the width direction (first side surface side).
  • the second side margin portion (20a) is a region that covers the inner layer portion (16), the first outer layer portion (18a), and the second outer layer portion (18b) from the other side in the width direction (second side surface side).
  • the first outer layer portion (18a), the second outer layer portion (18b), the first side margin portion (20a), and the second side margin portion (20b) are formed of a ceramic dielectric.
  • the external electrodes (8a, 8b) are composed of a first external electrode (8a) provided on the first outer end surface (14a) of the element body (6) and a second external electrode (8b) provided on the second outer end surface (14b).
  • the first external electrode (8a) and the second external electrode (8b) are not in contact with each other and are electrically separated from each other.
  • the size of the multilayer ceramic capacitor (100) or the element portion (6) is not particularly limited.
  • the length direction L dimension is 0.2 mm or more and 3.2 mm or less
  • the width direction W dimension is 0.1 mm or more and 2.5 mm or less
  • the stacking direction T dimension is 0.1 mm or more and 2.5 mm or less.
  • Figures 1 to 3 show the length direction L dimension as being larger than the width direction W dimension, the multilayer ceramic capacitor of this embodiment is not limited to having such dimensions.
  • the length direction L dimension may be smaller than the width direction W dimension.
  • the inner layer portion is a region in which the internal electrode layers (first internal electrode layer, second internal electrode layer) are alternately laminated via dielectric layers formed of ceramic dielectrics.
  • the dielectric layers are made of ceramic dielectrics produced by firing green sheets for the inner layers containing dielectric raw materials.
  • the ceramic dielectrics are made of sintered polycrystalline bodies (ceramics) in which a large number of dielectric particles are bonded via grain boundaries and triple junctions. In other words, they contain dielectric particles (dielectric grains) as the main component.
  • the main component is the component with the largest content in the ceramic dielectric, i.e., a component that accounts for 50% by mass or more.
  • the dielectric particles are composed of perovskite oxides.
  • Perovskite oxides have a composition represented by the general formula: ABO3 , and have a cubic crystal structure similar to a cubic crystal, such as a cubic, tetragonal, orthorhombic, or rhombohedral crystal, at room temperature.
  • A-site atoms the atoms of the A-site elements
  • B-site atoms the atoms of the B-site elements
  • Examples of the A-site elements include elements with relatively large ion sizes such as barium (Ba), calcium (Ca), and strontium (Sr), and examples of the B-site elements include elements with relatively small ion sizes such as titanium (Ti), zirconium (Zr), and hafnium (Hf).
  • the combination of the A-site elements and the B-site elements is not particularly limited as long as the perovskite structure is maintained.
  • Each of the A-site elements and the B-site elements may include only one type of element, or may include a combination of multiple elements.
  • the molar ratio of A-site elements to B-site elements may deviate from 1:1, so long as the perovskite structure is maintained.
  • perovskite oxides include barium titanate (BaTiO 3 )-based compounds, calcium titanate (CaTiO 3 )-based compounds, strontium titanate (SrTiO 3 )-based compounds, and mixed crystals and solid solutions thereof.
  • the A-site element contains barium (Ba) and the B-site element contains titanium (Ti). That is, the perovskite oxide is preferably a barium titanate (BaTiO 3 )-based compound.
  • BaTiO 3 -based compounds include not only BaTiO 3 but also compounds in which part of Ba in BaTiO 3 is replaced with other A-site elements such as Sr and/or Ca, or compounds in which part of Ti is replaced with other B-site elements such as Zr and/or Hf.
  • the ceramic dielectric may contain minor components.
  • minor components include, but are not limited to, rare earth elements (RE), magnesium (Mg), manganese (Mn), iron (Fe), chromium (Cr), cobalt (Co), nickel (Ni), silicon (Si), aluminum (Al), vanadium (V), and compounds thereof.
  • the minor components may contain the above-mentioned components alone or in combination. There are no limitations on the form in which the minor components exist. They may be contained in any of the dielectric particles, grain boundaries, and triple points.
  • the dielectric particles may include core-shell particles.
  • Core-shell particles are particles having a structure (core-shell structure) in which at least a part of the minor component is dissolved in a high concentration in the surface layer (shell portion) of the particle, and the minor component is dissolved in a low concentration or is not dissolved in the center (core portion) of the particle.
  • the dielectric particles may include homogeneous solid solution particles.
  • the thickness of the dielectric layer occupying the inner layer is preferably 0.3 ⁇ m or more and 0.5 ⁇ m or less.
  • the dielectric layer thicker than a specified value, it is possible to suppress the occurrence of insulation breakdown and deterioration of the life span of the multilayer ceramic capacitor when it is used.
  • the dielectric layer thicker than a specified value, the dielectric layer is made thinner, making it possible to further increase the capacity of the multilayer ceramic capacitor.
  • the number of dielectric layers constituting the outer layer and inner layer is 100 or more and 2000 or less.
  • the internal electrode layers are composed of an opposing electrode portion and an extraction electrode portion, and together with the dielectric layer, they constitute an internal layer portion.
  • the opposing electrode portion sandwiches the dielectric layer and functions as a capacitive element.
  • the extraction electrode portion electrically connects the opposing electrode portion and the external electrode.
  • the internal electrode layers contain a conductive metal.
  • known electrode materials such as nickel (Ni), copper (Cu), silver (Ag), palladium (Pd), silver (Ag)-palladium (Pd) alloy and/or gold (Au) may be used.
  • the internal electrode layers are produced by sintering a conductive paste layer printed on the surface of the internal layer green sheet.
  • the internal electrode layer may contain components other than conductive metals. Examples of other components include ceramic components that act as co-materials.
  • the thickness of the internal electrode layer is preferably 0.30 ⁇ m or more and 0.40 ⁇ m or less. By making the internal electrode thickness a specified value or more, problems such as electrode breakage can be prevented. By making the thickness less than a specified value, a decrease in the proportion of the dielectric layer in the capacitor can be prevented, which contributes to increased capacity.
  • the number of layers of the internal electrode layer is preferably 10 to 1,000.
  • the outer layer portions (first outer layer portion, second outer layer portion) are provided above and below the inner layer portion.
  • the outer layer portions are made of a ceramic dielectric and are regions that do not include an internal electrode layer therein.
  • the outer layer portions are produced by firing an outer layer green sheet that includes a dielectric material.
  • the side margins are provided along the side surfaces of the multilayer ceramic capacitor so as to sandwich the inner layer and the outer layer.
  • the side margins are also called side gaps or sides.
  • the side margins are made of a ceramic dielectric and are regions that do not include internal electrode layers. Providing the side margins can prevent moisture from penetrating into the inner layer from the side surfaces.
  • the side margin portion is formed separately from the inner layer portion and the outer layer portion when the multilayer ceramic capacitor is manufactured. Specifically, a green body for the side margin is attached to the side surface of the multilayer chip that will become the inner layer portion and the outer layer portion to create a green element portion, and this green element portion is then fired to manufacture the capacitor.
  • the ceramic dielectric that constitutes the side margin portion is not continuous in composition and/or microstructure with the ceramic dielectric that constitutes the inner layer portion and/or the outer layer portion. Therefore, there is a physical and chemical boundary between the side margin portion and the inner layer portion and/or the outer layer portion.
  • the external electrodes function as input/output terminals of the multilayer ceramic capacitor.
  • the first external electrode and the second external electrode are provided on both end surfaces of the multilayer ceramic capacitor.
  • the first external electrode is connected to the first internal electrode layer, and the second external electrode is connected to the second internal electrode layer.
  • a known configuration can be adopted for the external electrodes.
  • they may include a base electrode layer and a plating layer disposed thereon.
  • the external electrodes may be formed only by the plating layer, without providing a base electrode layer.
  • the ceramic dielectrics constituting the inner layer portion, the first outer layer portion, the second outer layer portion, the first side margin portion, and the second side margin portion each have a plurality of dielectric particles having voids therein. That is, these ceramic dielectrics are produced using hydrothermal synthesis dielectric powder.
  • the intragranular void ratio (N inner ) of the ceramic dielectric in the inner layer portion (hereinafter, sometimes collectively referred to as "inner layer ceramic")
  • the intragranular void ratio (N outer ) of the ceramic dielectric in the outer layer portion (first outer layer portion and second outer layer portion)
  • the intragranular void ratio (N side ) of the ceramic dielectric in the side margin portion (first side margin portion and second side margin portion)
  • the intragranular void ratio is the number of intragranular voids per unit area in a cross section (WT surface) crossing the longitudinal center portion of the multilayer ceramic capacitor.
  • the intragranular voids are voids present inside the dielectric particles constituting the ceramic dielectric. In other words, it is a region that exists inside a dielectric particle and does not contain solid components such as the main components that constitute the dielectric particle or intentionally added subcomponents. Therefore, it is distinguished from extra-particle voids that exist at the interface between particles or at triple junctions. Particles that have voids inside are called particles with voids.
  • the inner ceramic layer is a region that functions as a capacitance element.
  • intragranular voids are formed by using hydrothermally synthesized dielectric powder as a raw material.
  • hydrothermally synthesized dielectric powder it is possible to make the multilayer ceramic capacitor thinner and to increase its capacity.
  • particle size variation of the dielectric particles is suppressed, it is possible to improve the dielectric constant and reliability.
  • particles having intragranular voids have high crystallinity around the voids, and problems caused by diffusion of minor component elements can be suppressed.
  • the dielectric particles are core-shell particles
  • the diffusion and solid solution of the minor components do not proceed more than necessary even if the particles are grown in the firing process. Since grain growth is possible without destroying the core-shell structure, it is possible to achieve both a high dielectric constant, flat temperature characteristics, and excellent reliability.
  • the intragranular void ratio (N inner ) of the inner layer ceramic is relatively high in order to ensure good products and reliability.
  • N inner is preferably 8 pieces/ ⁇ m 2 or more and 23 pieces/ ⁇ m 2 or less, and more preferably 11 pieces/ ⁇ m 2 or more and 23 pieces/ ⁇ m 2 or less.
  • the intragranular void ratio is obtained by observing the cross section (WT surface) crossing the longitudinal center of the multilayer ceramic capacitor with a transmission electron microscope (TEM). Specifically, a TEM observation sample having a thickness of 80 nm including the WT surface is prepared.
  • the obtained sample is observed with a TEM in a 2 ⁇ m square field of view to count the number of intragranular voids.
  • the obtained number is then divided by the area of the ceramic part (dielectric layer) to calculate the number per unit area (1 ⁇ m 2 ).
  • the average pore size of the pores is preferably 10 nm or more and 50 nm or less, and particularly preferably 10 nm or more and 30 nm or less.
  • the outer layer ceramic and side margin ceramic surrounding the inner layer ceramic do not function as capacitive elements.
  • the outer layer ceramic or side margin ceramic has an excessive number of intragranular voids, there is a risk of reduced moisture resistance.
  • the outer layer ceramic and side margin ceramic do not have an internal electrode layer. They are not affected by stress from the internal electrode layer during the firing process in the manufacture of multilayer ceramic capacitors, and therefore tend to have lower sinterability than the inner layer ceramic. If the outer layer ceramic or side margin ceramic, which has low sinterability, has intragranular voids, moisture from the external environment can easily penetrate through these voids. The invaded moisture can reach the inner layer ceramic, which functions as a capacitive element, and cause problems such as a decrease in insulation resistance.
  • the outer layer ceramic and side margin ceramic it is effective to provide a certain degree of intragranular voids in the outer layer ceramic and side margin ceramic, provided that the above formulas (1) and (2) are satisfied. That is, to improve reliability by thinning the dielectric layer of the inner layer, it is necessary to suppress the variation in particle size of the dielectric particles throughout the electrically active inner layer ceramic. In order to suppress the variation in particle size of the active parts of the inner layer ceramic that contact the outer layer ceramic and side margin ceramic, it is advantageous for the outer layer ceramic and side margin ceramic to contain some intragranular voids.
  • the intragranular void ratio (N outer ) in the outer layer ceramic is preferably 3/ ⁇ m 2 or more and 13/ ⁇ m 2 or less, and more preferably 3/ ⁇ m 2 or more and 11/ ⁇ m 2 or less.
  • the intragranular void ratio (N side ) in the side margin ceramic is preferably 3/ ⁇ m 2 or more and 13/ ⁇ m 2 or less, and more preferably 3/ ⁇ m 2 or more and 11/ ⁇ m 2 or less.
  • the outer layer ceramic includes a portion corresponding to the first outer layer portion and a portion corresponding to the second outer layer portion.
  • the intragranular void ratio of the portion corresponding to the first outer layer portion and the intragranular void ratio of the portion corresponding to the second outer layer portion may be the same or different. As long as both are smaller than the intragranular void ratio of the inner layer ceramic, the relationship between the two is not limited.
  • the side margin ceramic includes a portion corresponding to the first side margin portion and a portion corresponding to the second side margin portion, but the intragranular void ratio of the portion corresponding to the first side margin portion and the intragranular void ratio of the portion corresponding to the second side margin portion may be the same or different.
  • the zirconium (Zr) concentration (Zr inner ) of the inner layer ceramic, the zirconium (Zr) concentration (Zr outer ) of the outer layer ceramic, and the zirconium (Zr) concentration (Zr side ) of the side margin ceramic satisfy both of the formula (3): Zr inner ⁇ Zr outer and the formula (4): Zr inner ⁇ Zr side .
  • a grain growth promoter such as Zr is added to the outer layer green sheet or the side margin green body and the amount is made larger than that of the inner layer green sheet, the intragranular void ratio of the outer layer part or the side margin part can be suppressed.
  • the concentration of the grain growth promoter (Zr, etc.) in the outer layer ceramic or the side margin ceramic is higher than that of the inner layer ceramic.
  • the Zr concentration at the location corresponding to the first outer layer and the Zr concentration at the location corresponding to the second outer layer may be the same or different, as long as they are both higher than the Zr concentration of the inner layer ceramic.
  • the Zr concentration at the location corresponding to the first side margin and the Zr concentration at the location corresponding to the second side margin may be the same or different.
  • the average particle size of the dielectric particles of the inner layer ceramic (D50 inner ), the average particle size of the dielectric particles of the outer layer ceramic (D50 outer ), and the average particle size of the dielectric particles of the side margin ceramic (D50 side ) satisfy both of formula (5): D50 inner ⁇ D50 outer and formula (6): D50 inner ⁇ D50 side .
  • the average grain size at the location corresponding to the first outer layer and the average grain size at the location corresponding to the second outer layer may be the same or different, as long as they are both larger than the average grain size of the inner layer ceramic.
  • the average grain size at the location corresponding to the first side margin and the average grain size at the location corresponding to the second side margin may be the same or different.
  • the average particle size (D50 inner ) of the dielectric particles of the inner layer ceramic is 130 nm or more and 210 nm or less.
  • the average particle size is the average particle size of the entire dielectric particles, including not only particles with holes but also particles without holes.
  • N inner , N outer , and N side may satisfy the formula (7): N outer ⁇ N side ⁇ N inner .
  • N outer ⁇ N side ⁇ N inner it is expected that the occurrence of cracks in the multilayer ceramic capacitor can be suppressed. That is, when mounting a multilayer ceramic capacitor on a substrate, a surface mounter hits the outer layer of the capacitor, and the impact may cause cracks in the outer layer. It is expected that the occurrence of cracks in the outer layer can be suppressed by suppressing the intragranular void ratio (N outer ) of the outer ceramic.
  • N inner , N outer , and N side may satisfy the formula (8): N side ⁇ N outer ⁇ N inner .
  • chipping of the multilayer ceramic capacitor can be reduced. That is, an impact is applied to the ridge of the multilayer ceramic capacitor during handling, and chipping may occur there. It is expected that chipping of the ridge can be suppressed by suppressing the intragranular void ratio (N side ) of the side margin ceramic.
  • a preferred manufacturing method includes the following steps: a step of synthesizing a main component powder for a ceramic dielectric (synthesizing step), a step of mixing a subcomponent raw material with the main component powder to obtain a dielectric raw material (mixing step), a step of adding and mixing a binder and a solvent to the dielectric raw material to form a slurry, and forming an inner layer green sheet and an outer layer green sheet from the obtained slurry (forming step), a step of forming a patterned conductive paste layer on the surface of the inner layer green sheet using a conductive paste for internal electrodes (printing step), a step of stacking a plurality of inner layer green sheets on which the conductive paste layer has been formed, stacking outer layer green sheets on and under them, and pressing the whole together to produce a laminate
  • the manufacturing conditions are controlled so that the intragranular void ratio of the inner layer ceramic (N inner ), the intragranular void ratio of the outer layer ceramic (N outer ), and the intragranular void ratio of the side margin ceramic (N side ) satisfy both of the formula (1): N outer ⁇ N inner and the formula (2): N side ⁇ N inner . Details of each process are described below.
  • the main component powder used for forming the ceramic dielectric is synthesized.
  • the main component powder is a dielectric powder having a perovskite structure (ABO 3 ) such as BaTiO 3 based compounds.
  • a hydrothermally synthesized dielectric powder is used as the main component powder. This makes it possible to manufacture a multilayer ceramic capacitor including dielectric particles having voids inside (particles with voids).
  • the main component powder only the hydrothermally synthesized dielectric powder may be used, or a combination of the hydrothermally synthesized dielectric powder and a powder synthesized by a method other than the hydrothermal method may be used.
  • the main component powder after synthesis may be pulverized to adjust the particle size.
  • the synthesis of the hydrothermally synthesized dielectric powder is carried out by hydrothermally reacting a raw material (A-site raw material) containing an A-site element constituting a perovskite structure and a raw material (B-site raw material) containing a B-site element under high temperature and high pressure. Specifically, the raw material is placed together with water in a sealed container such as an autoclave and heated to cause a hydrothermal reaction.
  • a hydroxide such as barium hydroxide (Ba(OH) 2 ) is used.
  • an oxide such as titanium oxide (TiO 2 ) or metatitanic acid (TiO(OH) 2 ) or its hydrate is used.
  • the heating temperature is not limited, but may be 150° C. or more and 250° C. or less.
  • the product obtained by the hydrothermal reaction is dried to obtain a dielectric powder.
  • the product may be subjected to a heat treatment in order to increase the crystallinity of the dielectric powder.
  • the heat treatment may be carried out at a temperature of, for example, 800° C. or more and 1000° C. or less.
  • ⁇ Mixing step> the main component powder is mixed with the auxiliary component (Ni, Re, Mg, Mn, Si, Al, V, etc.) raw material to obtain a dielectric raw material.
  • auxiliary component raw material a known ceramic raw material such as an oxide, a carbonate, a hydroxide, a nitrate, an organic acid salt, an alkoxide, and/or a chelate compound may be used.
  • a composition control agent for the main component powder may be added.
  • the main component powder is barium titanate (BaTiO 3 ) powder
  • adding a Ba raw material such as barium carbonate (BaCO 3 ) can control the main component composition of the ceramic dielectric contained in the multilayer ceramic capacitor.
  • the mixing method is not particularly limited. For example, a method of wet mixing and grinding the weighed main component powder and the auxiliary component raw material together with a grinding medium and pure water using a ball mill can be mentioned. When the wet mixing is performed, the mixture may be dried.
  • a binder and a solvent are added to and mixed with the dielectric material to form a slurry, and the resulting slurry is molded into inner layer green sheets and outer layer green sheets.
  • a binder a known organic binder such as a polyvinyl butyral binder may be used.
  • solvent a known organic solvent such as toluene or ethanol may be used. Additives such as a plasticizer may be added as necessary. Molding may be performed by a known method such as the lip method.
  • the sheet thickness after molding is, for example, 1 ⁇ m or less.
  • a patterned conductive paste layer is formed on the surface of the inner layer green sheet using a conductive paste.
  • the conductive paste layer becomes an internal electrode layer after firing.
  • the conductive metal contained in the conductive paste may be a conductive material such as nickel (Ni), copper (Cu), silver (Ag), palladium (Pd), or an alloy containing these.
  • a ceramic component acting as a co-material may also be added to the conductive paste.
  • the main component powder of the dielectric layer may be used as the ceramic component.
  • the method of forming the conductive paste layer is not particularly limited. For example, methods such as screen printing and gravure printing may be used.
  • ⁇ Lamination process> In the lamination process, multiple inner layer green sheets with conductive paste layers formed thereon are laminated, and outer layer green sheets are laminated above and below them. The whole is then pressed together to create a laminated block.
  • the inner layer green sheets undergo a firing process to become the ceramic dielectric (inner layer ceramic) that constitutes the inner layer portion of the multilayer ceramic capacitor.
  • the outer layer green sheets become the ceramic dielectric (outer layer ceramic) that constitutes the outer layer portion.
  • the number of green sheets to be laminated can be adjusted to obtain the required capacity.
  • the obtained laminated block is cut into laminated chips.
  • the cutting may be performed so that chips of a predetermined size are obtained and the conductive paste layers are exposed on the end faces and side faces of the laminated chips.
  • a side margin green body is attached to the side of the laminated chip to create a green element.
  • the side margin green body covers the conductive paste layer exposed on the side of the laminated chip.
  • the side margin green body becomes the side margin of the laminated ceramic capacitor after firing.
  • the raw material for the side margin green body can be the main component powder and the subcomponent raw material used to create the green sheets for the inner layers.
  • the side margin green body may be produced and attached by known methods. For example, a method may be used in which a green sheet is produced from the dielectric material that will be the raw material for the side margin portion, and this green sheet is adhered to the side of the laminated chip. In this case, to ensure adhesion of the green sheet, an adhesive assistant such as an organic solvent may be applied to the side of the laminated chip in advance. Another method may be used in which a paste is produced from the dielectric material, and this paste is applied to the side of the laminated chip and dried.
  • the side margin green body may be a single layer, or may be a laminate consisting of multiple layers. A side margin green body consisting of a laminate can be obtained by a method of stacking multiple green sheets on the side of the laminated chip, or by a method of repeatedly applying and drying a paste.
  • the obtained green body may be subjected to a barrel polishing process. This process makes it possible to round the corners and/or edges of the green body.
  • the green element part is subjected to a debindering process and a firing process to form an element part.
  • the firing process causes the conductive paste layer and the inner layer green sheet to be co-sintered to form the internal electrode layer and ceramic dielectric that form the inner layer part.
  • the outer layer green sheet is sintered to form the ceramic dielectric that forms the outer layer part.
  • the side margin green body is sintered to form the ceramic dielectric that forms the side margin part.
  • the conditions of the binder removal process may be determined according to the type of organic binder contained in the green sheet and the conductive paste layer.
  • the firing process may be performed at a temperature at which the laminated chip is sufficiently densified. For example, the firing process may be performed under conditions of holding the temperature at 1200°C or higher and 1300°C or lower for 0 minutes or longer and 10 minutes or shorter.
  • the firing process may be performed in an atmosphere in which the main component compound such as BaTiO 3 is not reduced and the oxidation of the conductive material is suppressed.
  • the firing process may be performed in a N 2 -H 2 -H 2 O air flow with an oxygen partial pressure of 1.8 ⁇ 10 -9 to 8.7 ⁇ 10 -10 MPa.
  • an annealing process may be performed after the firing process.
  • external electrodes are formed on the element part to produce a multilayer ceramic capacitor.
  • the external electrodes may be formed by a known method. For example, a conductive paste containing a conductive component such as Cu or Ni as a main component is applied and baked on the end faces of the element part where the internal electrodes are pulled out to form a base layer.
  • the base layer may be formed by applying a conductive paste to both end faces of the green element part before firing, followed by firing. After the base layer is formed, electrolytic plating may be performed to form a plating film of Ni, Sn, or the like on the surface of the base layer. This completes the multilayer ceramic capacitor.
  • the method of controlling the intragranular void ratio is not limited.
  • a method of adding a grain growth promoter or a grain growth inhibitor to the main component powder and adjusting the amount of the promoter can be used.
  • grain growth promoters include zirconium (Zr), silicon (Si), vanadium (V), and/or aluminum (Al). Dielectric particles grow during the firing process. As the grain growth progresses, the intragranular voids become smaller and may disappear. Therefore, if a grain growth promoter is added to the outer layer green sheet or the side margin green body in a larger amount than the inner layer green sheet, the intragranular void ratio of the outer layer ceramic or the side margin ceramic can be suppressed. In that case, in the multilayer ceramic capacitor finally obtained, the concentration of the grain growth promoter (Zr, etc.) in the outer layer ceramic or the side margin ceramic will be higher than that of the inner layer ceramic.
  • the main component powder is a perovskite oxide having a composition represented by the formula ABO3 , such as BaTiO3 .
  • ABO3 such as BaTiO3
  • the smaller the molar ratio (A/B ratio) of the A-site element (Ba, etc.) to the B-site element (Ti, etc.) the more the grain growth is promoted. Therefore, by reducing the molar ratio (A/B ratio) of the main component powder of the outer layer green sheet or side margin green body, the intragranular void ratio of the outer layer ceramic or side margin ceramic can be suppressed.
  • Another method is to adjust the particle size of raw material particles such as the main component powder.
  • the smaller the raw material particles the more the grains grow. Therefore, by using main component powder for the outer layer green sheets and side margin green bodies that has a smaller particle size than the main component powder for the inner layer green sheets, the intragranular void ratio of the outer layer ceramic and side margin ceramic can be reduced.
  • Another method is to add dielectric powder synthesized by a method other than the hydrothermal method, for example a solid-phase method, to the main component powder.
  • hydrothermally synthesized dielectric powder has intragranular voids
  • dielectric powder synthesized by a method other than the hydrothermal method does not have intragranular voids. Therefore, by using hydrothermally synthesized dielectric powder in combination with dielectric powder synthesized by a method other than the hydrothermal method, the intragranular void ratio can be controlled.
  • one method is to produce inner layer green sheets from hydrothermally synthesized dielectric powder, while producing outer layer green sheets and side margin green bodies from a mixed powder of hydrothermally synthesized dielectric powder and dielectric powder synthesized by the solid-phase method.
  • Example 1 (1) Fabrication of Multilayer Ceramic Capacitor [Example 1]
  • inner layer green sheets, outer layer green sheets, and side margin green bodies were produced using barium titanate (BaTiO 3 ) powder synthesized by a hydrothermal method as the main component powder, and a multilayer ceramic capacitor was produced using these.
  • BaTiO 3 barium titanate
  • Barium titanate (BaTiO 3 ) powder was synthesized by hydrothermal method. First, titanium oxide (TiO 2 ) powder and barium hydroxide (Ba(OH) 2 ) powder were weighed, and pure water was added to prepare a slurry. The prepared slurry was then placed in a sealed container, and the temperature of the slurry was raised to 200-250°C while stirring. The temperature was then kept at 200-250°C for 4-24 hours to allow the liquid phase reaction to proceed. After that, the internal pressure of the sealed container was returned to atmospheric pressure, heating of the sealed container was stopped, and the slurry was left as it was. After cooling, the slurry was removed from the sealed container and placed in a dryer to evaporate the water. In this way, hydrothermally synthesized BaTiO 3 powder with an average particle size of 130 nm was obtained.
  • a polyvinyl butyral binder and ethanol as an organic solvent were added to the obtained dielectric raw material, and the mixture was wet-mixed by a ball mill for a predetermined time to prepare a slurry. This slurry was formed into a sheet to prepare an inner layer green sheet.
  • BaCO3 and ZrO2 were added to hydrothermally synthesized BaTiO3 powder (average particle size 130 nm), and the resulting mixture was wet-ground in water using a ZrO2 ball mill for 24 hours, and then dried and heat-treated to obtain a dielectric raw material.
  • the amount of BaCO3 added was adjusted so that the molar ratio (Ba/Ti ratio) of the ceramic dielectric constituting the outer layer part of the finally obtained multilayer ceramic capacitor was 1.0025.
  • the amount of ZrO2 added was 0.3 mass% relative to the BaTiO3 powder.
  • a polyvinyl butyral binder and ethanol as an organic solvent were added to the obtained dielectric raw material, and the mixture was wet-mixed by a ball mill for a predetermined time to prepare a slurry. This slurry was formed into a sheet to prepare an outer layer green sheet.
  • BaCO3 and ZrO2 were added to hydrothermally synthesized BaTiO3 powder (average particle size 130 nm), and the resulting mixture was wet-ground in water using a ZrO2 ball mill for 24 hours, and then dried and heat-treated to obtain a dielectric raw material.
  • the amount of BaCO3 added was adjusted so that the molar ratio (Ba/Ti ratio) of the ceramic dielectric constituting the side margin portion of the final multilayer ceramic capacitor was 1.0025.
  • the amount of ZrO2 added was 0.3 mass% relative to the BaTiO3 powder.
  • a polyvinyl butyral binder and ethanol, an organic solvent were added to the obtained dielectric raw material, and the mixture was wet-mixed by a ball mill for a predetermined time to prepare a slurry.
  • This slurry was formed into a sheet to prepare a side margin green body.
  • a conductive paste mainly made of Ni was screen-printed on the surface of the obtained green sheet for the inner layer, and a conductive paste layer to be an internal electrode layer was patterned. Then, a plurality of green sheets for the inner layer on which the conductive paste layer was formed were laminated, and green sheets for the outer layer on which the conductive paste layer was not formed were arranged above and below the green sheets, and the whole was pressed to produce a laminated block. The obtained laminated block was then cut with a dicing saw to produce a laminated chip. The lamination was performed so that the ends from which the conductive paste layer was drawn out were staggered. The cutting was also performed so that the conductive paste layer was exposed on the side surface, and the drawn-out portion of the conductive paste layer was exposed on the end surface.
  • the obtained green element part was heat treated in an N2 gas flow at a maximum temperature of 270°C, and further heat treated in an N2 - H2O - H2 gas flow at a maximum temperature of 800°C. Thereafter, it was sintered in an N2 - H2O - H2 gas flow. The sintering was performed under the conditions of a maximum temperature of 1230-1400°C, a heating rate of 20-60/sec, a keeping time of 60 minutes, and an oxygen partial pressure of 5.0x10-13 to 1.7x10-12 MPa. Next, it was heat treated in an N2 - H2O - H2 gas flow at a maximum temperature of 1050°C for 60 minutes. In this way, an element part was obtained.
  • a conductive paste mainly composed of copper (Cu) was applied to the end faces of the element part obtained by firing, from which the internal electrode layers were drawn out.
  • the applied conductive paste was then baked at 900°C to form the base layer for the external electrode.
  • Ni plating and Sn plating were applied, in that order, to the surface of the base layer by wet plating. In this way, a multilayer ceramic capacitor was produced.
  • Example 2 when preparing the green sheets for the inner layers, hydrothermally synthesized BaTiO3 powder (average particle size 80 nm) was used instead of hydrothermally synthesized BaTiO3 powder (average particle size 130 nm). Except for this, a multilayer ceramic capacitor was prepared in the same manner as in Example 1. The hydrothermally synthesized BaTiO3 powder (average particle size 80 nm) was synthesized in the same manner as the hydrothermally synthesized BaTiO3 powder (average particle size 130 nm) except that the slurry temperature during hydrothermal synthesis was lowered.
  • Example 3 In Example 3, ZrO2 was not added when preparing the outer layer ceramic green sheets and side margin green bodies. The amount of BaCO3 added was adjusted so that the molar ratio (Ba/Ti ratio) of the outer layer ceramic and side margin ceramic was 1.0000. A multilayer ceramic capacitor was prepared in the same manner as in Example 1 except for the above.
  • Example 4 In Example 4, the amount of ZrO2 added when preparing the outer layer ceramic green sheets and the side margin green bodies was changed from 0.3% by mass to 0.5% by mass. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Example 5 In Example 5, the grinding time for preparing the outer layer ceramic green sheets and the side margin green bodies was changed from 24 hours to 48 hours, and ZrO2 was not added. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Example 6 In Example 6, the grinding time in preparing the side margin green body was changed from 24 hours to 48 hours, and ZrO2 was not added. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Example 7 In Example 7, the grinding time during preparation of the outer layer ceramic green sheets was changed from 24 hours to 48 hours, and ZrO2 was not added. Except for this, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Example 8 In Example 8, ZrO2 was added together with BaCO3 when preparing the ceramic green sheets for the inner layer, and the amount of ZrO2 added ( ZrO2 added amount) was 0.1 mass% relative to the BaTiO3 powder.
  • a multilayer ceramic capacitor was prepared in the same manner as in Example 1 except for the above.
  • Example 9 when preparing the ceramic green sheets for the outer layer, a mixed powder containing 70% by mass of hydrothermally synthesized BaTiO3 powder (average particle size 130 nm) and 30% by mass of solid-phase synthesized BaTiO3 powder (average particle size 130 nm) was used as the main component powder. In addition, the amount of BaCO3 added when preparing the ceramic green sheets for the outer layer and the side margin green body was adjusted so that the molar ratio (Ba/Ti ratio) of the outer layer ceramic and the side margin ceramic was 1.0050. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Example 10 when preparing the ceramic green sheets for the outer layer, a mixed powder containing 85% by mass of hydrothermally synthesized BaTiO3 powder (average particle size 130 nm) and 15% by mass of solid-phase synthesized BaTiO3 powder (average particle size 130 nm) was used as the main component powder. In addition, no ZrO2 was added when preparing the ceramic green sheets for the outer layer and the side margin green body. Furthermore, the amount of BaCO3 added was adjusted so that the molar ratio (Ba/Ti ratio) of the outer layer ceramic and the side margin ceramic was 1.0050. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Example 11 In Example 11, ZrO2 was added together with BaCO3 when preparing the ceramic green sheets for the inner layer, and the amount added ( ZrO2 added amount) was 0.1 mass% relative to the BaTiO3 powder. In addition, ZrO2 was not added when preparing the ceramic green sheets for the outer layer and the side margin green body. Furthermore, the amount of BaCO3 added was adjusted so that the molar ratio (Ba/Ti ratio) of the outer layer ceramic was 1.0000 and the molar ratio (Ba/Ti ratio) of the side margin ceramic was 1.0050. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Comparative Example 1 In Comparative Example 1, when preparing the ceramic green sheets for the inner layer, a mixed powder containing 10% by mass of hydrothermally synthesized BaTiO3 powder (average particle size 130 nm) and 90% by mass of solid-phase synthesized BaTiO3 powder (average particle size 130 nm) was used as the main component powder. In addition, the grinding time when preparing the ceramic green sheets for the outer layer and the side margin green body was changed from 24 hours to 12 hours, and ZrO2 was not added. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Comparative Example 2 In Comparative Example 2, the grinding time for preparing the outer layer ceramic green sheets and the side margin green bodies was changed from 24 hours to 12 hours, and ZrO2 was not added. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Comparative Example 3 In Comparative Example 3, the grinding time during preparation of the outer layer ceramic green sheets was changed from 24 hours to 12 hours, and ZrO2 was not added. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • Comparative Example 4 In Comparative Example 4, the grinding time during preparation of the side margin green body was changed from 24 hours to 12 hours, and ZrO2 was not added. Otherwise, a multilayer ceramic capacitor was prepared in the same manner as in Example 1.
  • the WT surface of the multilayer ceramic capacitor was observed using a transmission electron microscope (TEM) to examine the intragranular void ratio. Specifically, the multilayer ceramic capacitor was polished to the center in the length direction to expose the WT surface, and further processed to prepare a TEM observation sample with a thickness of 80 nm including the WT surface. Then, TEM observation of the obtained sample was performed. At this time, the cross section was divided into an inner layer part, an outer layer part, and a side margin part, and observation was performed on the ceramic dielectric part near the center in the W direction and the T direction of the inner layer part, near the center in the W direction and the T direction of the outer layer part, and near the center in the W direction and the T direction of the side margin part.
  • TEM transmission electron microscope
  • the number of voids present in the dielectric particles was counted, and the obtained number was divided by the area of the ceramic part to calculate the number per unit area (1 ⁇ m 2 ).
  • the WT surface of the multilayer ceramic capacitor was observed using a scanning electron microscope (SEM) to examine the thickness of the dielectric layer and the particle size (D50) of the dielectric particles.
  • SEM scanning electron microscope
  • the multilayer ceramic capacitor was polished to the center in the length (L) direction to expose the cross section (WT surface).
  • the thickness of the dielectric layer of the inner layer located near the center in the thickness direction was measured on a total of five lines, including the center line in the width direction W and two lines drawn equally spaced on both sides from this center line toward the width direction W, and the average value was taken as the thickness of the dielectric layer.
  • SEM images of the dielectric particles in the dielectric layer in the exposed cross section were taken under the conditions of a magnification of 5000 times, an acceleration voltage of 15 kV, and a field of view of 30 ⁇ m x 30 ⁇ m.
  • the dielectric layer portion near the center in the W direction and T direction of the inner layer portion was imaged.
  • the edges of all the dielectric particles were recognized using image processing software to calculate the cross-sectional area of the particles, and the circle equivalent diameter was calculated from this area as the diameter of the particle.
  • the diameters of all the dielectric particles included in the imaged range were measured, excluding the dielectric particles that were missing and imaged, and the average value was calculated to obtain the average particle diameter (D50 inner ) of the dielectric particles in the inner layer ceramic.
  • images were taken near the center in the W direction and T direction of the outer layer portion and near the center in the W direction and T direction of the side margin portion, and the average particle diameter (D50 outer ) of the dielectric particles in the outer layer ceramic and the average particle diameter (D50 side ) of the dielectric particles in the side margin ceramic were obtained.
  • ⁇ Moisture resistance load test> A moisture resistance load test was conducted for 100 samples under conditions of 85°C, 85% relative humidity, and 6.3V. After 250 hours, 500 hours, or 1000 hours had elapsed, the samples were removed from the test tank, and insulation resistance (IR) was measured when a voltage of 6.3V was applied to the samples at room temperature for 60 seconds. Then, LogIR>4 was used as the standard, and samples that all met the standard were judged as pass ( ⁇ ), and samples that had at least one LogIR ⁇ 4 were judged as fail ( ⁇ ). Furthermore, the results of the moisture resistance test were judged according to the following criteria.
  • Examples 1 to 11 both the intragranular void ratios (N outer , N side ) in the outer layer and the side margin were smaller than the intragranular void ratio (N inner ) in the inner layer. Therefore, the results of the moisture resistance load test were good, and the samples passed after 250 hours. In particular, Examples 1, 2, and 4 to 8 showed particularly good results in the moisture resistance load test, and passed even after 1000 hours.
  • Example 9 which has a relatively high molar ratio, had relatively low moisture resistance and the moisture load test result was "Good”.
  • Example 10 had a moisture load test result of "Good”, the molar ratio was high and the Zr content was low. Therefore, although it passed after 250 hours, it failed after 500 hours.
  • this embodiment provides a multilayer ceramic capacitor that is particularly excellent in terms of moisture resistance.
  • the above describes an embodiment of the present invention, but the present invention is not limited to the embodiment, and can be implemented in various forms without departing from the gist of the present invention.
  • the present invention includes the following combinations.
  • dielectric layer 4 internal electrode layer 6 element body portion 8a first external electrode 8b second external electrode 10a first external main surface 10b second external main surface 12a first external side surface 12b second external side surface 14a first external end surface 14b second external end surface 16 internal layer portion 18a first external layer 18b second external layer 20a first side margin portion 20b second side margin portion 22 internal region 100 multilayer ceramic capacitor

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