Multilayer ceramic capacitor

Abstract

To provide a multilayer ceramic capacitor in which the occurrence of structural defects is suppressed. [Solution] The multilayer ceramic capacitor comprises a base body and external electrodes. The base body includes a dielectric layer and an internal electrode layer stacked in the stacking direction T, and has a first main surface and a second main surface facing the stacking direction T, a first side surface and a second side surface facing the width direction W perpendicular to the stacking direction T, and a first end surface and a second end surface facing the length direction perpendicular to the stacking direction T and the width direction W. The external electrodes are provided on each of the first and second end surfaces and connected to the internal electrode layer. When the base body is viewed in cross-section in the TW direction at the center in the length direction, the internal electrode layer has a first internal electrode layer 118A whose both ends 151A in the width direction W are curved toward the second main surface, and a second internal electrode layer 118B located toward the second main surface than the first internal electrode layer 118A, whose both ends 151B in the width direction W are curved toward the first main surface. The number of second internal electrode layers 118B is greater than the number of first internal electrode layers 118A.

Description

Technical Field

[0001] This disclosure relates to a multilayer ceramic capacitor.

Background Art

[0002] Conventionally, a multilayer ceramic capacitor including a substantially rectangular parallelepiped body portion in which a plurality of dielectric layers and internal electrode layers are alternately laminated, and external electrodes provided on a pair of end faces in the length direction of the body portion is known.

[0003] Generally, a plurality of internal electrode layers are formed by laminating mother sheets provided with internal electrode patterns. At that time, both end portions in the width direction of some of the internal electrode layers may be configured to curve toward the central portion side in the lamination direction due to the self-weight of the internal electrode layer or the load of the layer laminated on the internal electrode layer. As an example of such a multilayer ceramic capacitor, Japanese Patent Application Laid-Open No. 2021-19186 (Patent Document 1) can be cited as a prior art document in which an example of such a multilayer ceramic capacitor is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] When the internal electrode layer curves as described above, the risk of occurrence of a structural defect in which adjacent internal electrodes in the lamination direction come into contact increases. Such a structural defect can cause a short circuit and may reduce the reliability of the multilayer ceramic capacitor.

[0006] Therefore, this disclosure has been made to solve the above-described problems, and an object thereof is to provide a multilayer ceramic capacitor in which the occurrence of structural defects is suppressed.

Means for Solving the Problems

[0007] A multilayer ceramic capacitor according to this disclosure comprises a base body and external electrodes. The base body includes a plurality of dielectric layers and a plurality of internal electrode layers stacked in the stacking direction, and has a first main surface and a second main surface facing the stacking direction, a first side surface and a second side surface facing the width direction perpendicular to the stacking direction, and a first end surface and a second end surface facing the length direction perpendicular to the stacking direction and the width direction. The external electrodes are provided on each of the first and second end surfaces and connected to the plurality of internal electrode layers. When the base body is viewed in a cross-section extending in the stacking direction and the width direction at the center of the length direction, the plurality of internal electrode layers include a plurality of first internal electrode layers whose ends in the width direction are curved toward the second main surface, and a plurality of second internal electrode layers located toward the second main surface than the plurality of first internal electrode layers, whose ends in the width direction are curved toward the first main surface. The number of the plurality of second internal electrode layers is greater than the number of the plurality of first internal electrode layers.

[0008] In the multilayer ceramic capacitor based on the above disclosure, the thickness dimension of each of the plurality of dielectric layers may be 0.4 μm or more and 6.2 μm or less.

[0009] In the multilayer ceramic capacitor according to the above disclosure, when the base portion is viewed in cross-section, the curvature of both ends in the width direction of the first internal electrode layer located furthest towards the first main surface among the plurality of first internal electrode layers may be greater than the curvature of both ends in the width direction of the second internal electrode layer located furthest towards the second main surface among the plurality of second internal electrode layers.

[0010] In the multilayer ceramic capacitor according to the above disclosure, when the base portion is viewed in cross-section, the plurality of internal electrode layers may further have a plurality of third internal electrode layers located between the plurality of first internal electrode layers and the plurality of second internal electrode layers in the stacking direction, in which case when the base portion is viewed in cross-section, the plurality of third internal electrode layers may extend substantially linearly along the width direction.

[0011] In the multilayer ceramic capacitor based on the above disclosure, the number of the plurality of third internal electrode layers may be less than the number of the plurality of first internal electrode layers.

[0012] In the multilayer ceramic capacitor based on the above disclosure, the base portion may include a first ridge portion which is the part where the first side surface and the first main surface intersect, and a second ridge portion which is the part where the first side surface and the second main surface intersect. In this case, when the base portion is viewed in cross-section, the curvature of the first ridge portion may be smaller than the curvature of the second ridge portion. [Effects of the Invention]

[0013] According to this disclosure, it is possible to provide a multilayer ceramic capacitor in which the occurrence of structural defects is suppressed. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic perspective view showing the appearance of a multilayer ceramic capacitor according to an embodiment. [Figure 2] This is a schematic cross-sectional view along the line II-II shown in Figure 1. [Figure 3] This is a schematic cross-sectional view along the line III-III shown in Figure 1. [Figure 4] Figure 2 shows a schematic cross-sectional view taken from the direction of the arrow along line IV-IV. [Figure 5] Figure 2 is a schematic cross-sectional view taken from the direction of the VV line arrow. [Figure 6] This is a schematic cross-sectional view of the internal electrode layer extracted from Figure 3. [Figure 7] This is a flowchart showing a method for manufacturing a multilayer ceramic capacitor according to an embodiment.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the embodiments shown below, the same or common parts are denoted by the same reference numerals in the drawings, and the description thereof will not be repeated.

[0016] In the drawings, the length direction of the body portion of the multilayer ceramic capacitor is indicated by L, the width direction of the body portion is indicated by W, and the stacking direction of the body portion is indicated by T. The body portion will be described in detail later.

[0017] (Embodiment) <A. Configuration of Multilayer Ceramic Capacitor> FIG. 1 is a perspective view schematically showing the appearance of a multilayer ceramic capacitor according to an embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II shown in FIG. 1. Specifically, FIG. 2 is a schematic view of the body portion seen in a cross-section extending in the stacking direction T and the length direction L at the central portion in the width direction W. Hereinafter, for convenience of explanation, this cross-section will also be referred to as cross-section Q. FIG. 3 is a schematic cross-sectional view taken along line III-III shown in FIG. 1. Specifically, FIG. 3 is a schematic view of the body portion seen in a cross-section extending in the stacking direction T and the width direction W at the central portion in the length direction L. Hereinafter, for convenience of explanation, this cross-section will also be referred to as cross-section P. FIG. 4 is a schematic cross-sectional view taken along line IV-IV shown in FIG. 2. FIG. 5 is a schematic cross-sectional view taken along line V-V shown in FIG. 2. FIG. 6 is a schematic cross-sectional view of the internal electrode layer extracted from FIG. 3. First, the configuration of the multilayer ceramic capacitor 100 according to the present embodiment will be described with reference to FIGS. 1 to 6.

[0018] As shown in FIGS. 1 to 6, the multilayer ceramic capacitor 100 according to the present embodiment includes a body portion 110 and external electrodes. The external electrodes are composed of a first external electrode 120 and a second external electrode 13<strong>0< / strong>.

[0019] The base body portion 110 has a substantially rectangular parallelepiped shape. The base body portion 110 has a first main surface 111 and a second main surface 112 that face each other in the stacking direction T, a first side surface 113 and a second side surface 114 that face each other in the width direction W orthogonal to the stacking direction T, and a first end surface 115 and a second end surface 116 that face each other in the length direction L orthogonal to the stacking direction T and the width direction W.

[0020] The base body portion 110 includes a first ridge line portion 110a, a second ridge line portion 110b, a third ridge line portion 110c, and a fourth ridge line portion 110d. The first ridge line portion 110a is formed at a portion where the first side surface 113 and the first main surface 111 intersect. The second ridge line portion 110b is formed at a portion where the first side surface 113 and the second main surface 112 intersect. The third ridge line portion 110c is formed at a portion where the second side surface 114 and the first main surface 111 intersect. The fourth ridge line portion 110d is formed at a portion where the second side surface 114 and the second main surface 112 intersect.

[0021] The first ridge line portion 110a, the second ridge line portion 110b, the third ridge line portion 110c, and the fourth ridge line portion 110d are all rounded. When the base body portion 110 is viewed in cross-section P (see FIG. 3), the curvature of the first ridge line portion 110a is smaller than the curvature of the second ridge line portion 110b. The curvature of the third ridge line portion 110c is smaller than the curvature of the fourth ridge line portion 110d. The curvature of the first ridge line portion 110a and the curvature of the third ridge line portion 110c are substantially the same. The curvature of the second ridge line portion 110b and the curvature of the fourth ridge line portion 110d are substantially the same.

[0022] The base body portion 110 includes a first end-face-side ridge line portion 110e, a second end-face-side ridge line portion 110f, a third end-face-side ridge line portion 110g, and a fourth end-face-side ridge line portion 110h. The first end-face-side ridge line portion 110e is formed at a portion where the first end surface 115 and the first main surface 111 intersect. The second end-face-side ridge line portion 110f is formed at a portion where the first end surface 115 and the second main surface 112 intersect. The third end-face-side ridge line portion 110g is formed at a portion where the second end surface 116 and the first main surface 111 intersect. The fourth end-face-side ridge line portion 110h is formed at a portion where the second end surface 116 and the second main surface 112 intersect.

[0023] The first ridge section 110e, the second ridge section 110f, the third ridge section 110g, and the fourth ridge section 110h on the end face side are all rounded. When the base body 110 is viewed in cross-section Q (see Figure 2), the curvature of the first ridge section 110e on the end face side is smaller than the curvature of the second ridge section 110f on the end face side. The curvature of the third ridge section 110g on the end face side is smaller than the curvature of the fourth ridge section 110h on the end face side. The curvature of the first ridge section 110e and the curvature of the third ridge section 110g on the end face side are approximately the same. The curvature of the second ridge section 110f and the curvature of the fourth ridge section 110h on the end face side are approximately the same.

[0024] The curvature of the first ridge portion 110a when the base portion 110 is viewed in cross-section P is smaller than the curvature of the first ridge portion 110e on the end face side when the base portion 110 is viewed in cross-section Q. The curvature of the second ridge portion 110b when the base portion 110 is viewed in cross-section P is smaller than the curvature of the second ridge portion 110f on the end face side when the base portion 110 is viewed in cross-section Q.

[0025] The base body 110 includes multiple corners. The corners are the points where three faces of the base body 110 intersect. That is, the multiple corners are formed by the points where three adjacent faces from the first main face 111, the second main face 112, the first side face 113, the second side face 114, the first end face 115, and the second end face 116 intersect. It is preferable that all of the multiple corners are rounded.

[0026] The width dimension W of the base body 110 is preferably 0.05 mm or more and 2.5 mm or less. The stacking direction T of the base body 110 is preferably 0.05 mm or more and 2.5 mm or less. The length dimension L of the base body 110 is preferably 0.1 mm or more and 3.2 mm or less. Note that these dimensions are values ​​excluding tolerances.

[0027] The first external electrode 120 is provided on the first end face 115. More specifically, the first external electrode 120 is formed over the entire first end face 115 and is also formed to wrap around from the first end face 115 to the first main surface 111, the second main surface 112, the first side surface 113, and the second side surface 114.

[0028] The second external electrode 130 is provided on the second end face 116. More specifically, the second external electrode 130 is formed over the entire second end face 116 and is also formed to wrap around from the second end face 116 to the first main surface 111, the second main surface 112, the first side surface 113, and the second side surface 114.

[0029] The first external electrode 120 and the second external electrode 130 each comprise, for example, a base electrode layer and a plating layer disposed on the base electrode layer. The base electrode layer includes at least one layer from among baked electrode layers, resin electrode layers, and thin-film electrode layers. In Figure 2, etc., the base electrode layer and the plating layer are shown together as a single layer.

[0030] The baked electrode layer is a layer containing glass and metal, and may be a single layer or multiple layers. The baked electrode layer is composed of, for example, one metal selected from the group consisting of Ni, Cu, Ag, Pd, and Au, or an alloy containing this metal, such as an alloy of Ag and Pd.

[0031] The baked electrode layer can be formed by applying a conductive paste containing glass and metal to the base body 110 and baking it. The baking may be performed simultaneously with the firing of the base body 110, or after the firing of the base body 110.

[0032] The resin electrode layer can be formed, for example, as a layer containing conductive particles and a thermosetting resin. When forming the resin electrode layer, the resin electrode layer may be formed directly on the base portion 110 without forming a baked electrode layer. The resin electrode layer may be a single layer or multiple layers.

[0033] The thin-film electrode layer is, for example, a layer of metal particles with a thickness of 1 μm or less, and can be formed by known thin-film formation methods such as sputtering or vapor deposition.

[0034] The plating layer placed on the base electrode layer is composed of, for example, one metal selected from the group consisting of Ni, Cu, Ag, Pd, and Au, or an alloy containing this metal, for example, an alloy of Ag and Pd. The plating layer may be one layer or multiple layers. However, it is preferable that the plating layer has a two-layer structure in which a Sn plating layer is formed on top of a Ni plating layer. The Ni plating layer has the function of preventing the base electrode layer from being corroded by the solder when mounting the multilayer ceramic capacitor 100. The Sn plating layer has the function of improving the wettability of the solder when mounting the multilayer ceramic capacitor 100.

[0035] The base body 110 has a plurality of internal electrode layers 118 and a plurality of dielectric layers that are alternately stacked along the stacking direction T.

[0036] The plurality of dielectric layers consist of a first outer layer 119a including a first main surface 111, a second outer layer 119b including a second main surface 112, and an inner layer 119c located between adjacent inner electrode layers 118 in the stacking direction T. The number of dielectric layers is preferably 100 to 1000. The thickness dimensions of the first outer layer 119a and the second outer layer 119b are preferably 20 μm to 120 μm. The thickness dimension of each inner layer 119c is preferably 0.4 μm to 6.2 μm.

[0037] Each of the multiple dielectric layers can be a dielectric ceramic containing components such as BaTiO3, CaTiO3, SrTiO3, or CaZrO3 as the ceramic material. Alternatively, these can be used with minor components such as Mn compounds, Fe compounds, Cr compounds, Co compounds, or Ni compounds added to the main components.

[0038] In this embodiment, the first outer layer 119a, the second outer layer 119b, and the inner layer 119c are substantially the same ceramic material system. Substantially the same ceramic material system means that the mixing ratio of the raw ceramic materials is substantially the same, and the range of variation in ceramic composition due to variations in mixing ratio and processing steps is included within substantially the same ceramic material system.

[0039] The multiple internal electrode layers 118 each have a first layer 118a and a second layer 118b. Inside the base body 110, the first layer 118a and the second layer 118b are stacked alternately along the stacking direction T. Each of the multiple first layer 118a and the multiple second layer 118b is provided parallel to the length direction L and the width direction W. An inner layer 119c is placed between adjacent first layer 118a and second layer 118b in the stacking direction T. That is, adjacent first layer 118a and second layer 118b in the stacking direction T face each other with the inner layer 119c in between.

[0040] The first layer 118a is drawn out to the first end face 115. The first end face 115 is covered by the first external electrode 120. The first external electrode 120 is electrically connected to the first layer 118a. The second layer 118b is drawn out to the second end face 116. The second end face 116 is covered by the second external electrode 130. The second external electrode 130 is electrically connected to the second layer 118b.

[0041] In Figures 2 and 3, examples are shown in which seven sheets each of the first layer 118a and the second layer 118b are provided, but the number of sheets of each of the first layer 118a and the second layer 118b is not particularly limited to seven. The total number of sheets of the first layer 118a and the second layer 118b is preferably between 100 and 1000. The thickness of each of the first layer 118a and the second layer 118b is preferably between 0.4 μm and 1.2 μm.

[0042] Here, the thickness dimension of the internal electrode layer 118 described above can be calculated by the following method. First, the base body 110 is polished so that the WT cross-section of the base body 110 is exposed in the center of the length direction L. Next, a total of five lines are virtually set, consisting of a center line passing through the center of the width direction W and extending along the stacking direction T, two virtual lines parallel to the center line and arranged at equal intervals toward the first side surface 113 from the center line, and two virtual lines parallel to the center line and arranged at equal intervals toward the second side surface 114 from the center line. Next, the thickness dimension of the internal electrode layer 118 is measured along each line. Next, the average value of the five measurements obtained in this way is calculated. The average value calculated in this way becomes the thickness dimension of the internal electrode layer 118. It is preferable that the spacing between adjacent lines is 5 μm or more.

[0043] When calculating the overall average thickness dimension of the multiple internal electrode layers 118, the following method can be used, for example. The thickness dimension of the internal electrode layer 118 along each of the lines described above is measured at three locations: on the side of the first main surface 111 in the stacking direction T, on the side of the second main surface 112 in the stacking direction T, and in the central part in the stacking direction T. The average value is calculated at each location as described above. Then, the average of these three average values ​​is calculated. The average value calculated in this way is taken as the overall average thickness dimension of the multiple internal electrode layers 118.

[0044] Each of the measurements described above can be performed by observing the aforementioned cross-section using a scanning electron microscope or similar device. Although not explained here, the thickness of the dielectric layer can also be calculated using the same method as described above.

[0045] The first layer 118a includes a first opposing portion 118a1 and a first leading portion 118a2. The first opposing portion 118a1 faces the adjacent second layer 118b in the stacking direction T. The first leading portion 118a2 connects the first opposing portion 118a1 and the first external electrode 120. The first leading portion 118a2 is led out toward the first end face 115. The first opposing portion 118a1 and the first leading portion 118a2 are integrally constructed.

[0046] The second layer 118b includes a second opposing portion 118b1 and a second leading portion 118b2. The second opposing portion 118b1 faces the adjacent first layer 118a in the stacking direction T. The second leading portion 118b2 connects the second opposing portion 118b1 and the second external electrode 130. The second leading portion 118b2 is led out toward the second end face 116. The second opposing portion 118b1 and the second leading portion 118b2 are integrally constructed.

[0047] Each of the first layer 118a and the second layer 118b contains one metal selected from the group consisting of Ni, Cu, Ag, Pd, and Au, or an alloy containing such a metal. An example of such an alloy is an alloy of Ag and Pd. In this embodiment, each of the first layer 118a and the second layer 118b contains Ni as its main component. Each of the first layer 118a and the second layer 118b may further contain dielectric particles of the same composition system as the ceramic contained in the dielectric layer. In addition, each of the first layer 118a and the second layer 118b may contain Sn at the interface with the dielectric layer.

[0048] The base body 110 includes an inner layer C. The inner layer C has capacitance because the first opposing portion 118a1 of the first layer 118a and the second opposing portion 118b1 of the second layer 118b are stacked in the stacking direction T.

[0049] In this embodiment, the dimensions of the first outer layer 119a in the stacking direction T and the dimensions of the second outer layer 119b in the stacking direction T are substantially the same. Therefore, the inner layer C sandwiched between the first outer layer 119a and the second outer layer 119b in the stacking direction T is located in the center of the base body 110 in the stacking direction T. The inner layer C may be biased towards the first main surface 111 side or towards the second main surface 112 side in the stacking direction T.

[0050] Here, as shown in Figures 3 and 6, when the base body 110 is viewed in a cross-section extending in the stacking direction T and width direction W at the central part in the length direction L, the multiple internal electrode layers 118 have multiple first internal electrode layers 118A, multiple second internal electrode layers 118B, and multiple third internal electrode layers 118C.

[0051] Multiple first internal electrode layers 118A are located on the first main surface 111 side in the stacking direction T. Multiple second internal electrode layers 118B are located on the second main surface 112 side of the multiple first internal electrode layers 118A in the stacking direction T. Multiple third internal electrode layers 118C are located between the multiple first internal electrode layers 118A and the multiple second internal electrode layers 118B in the stacking direction T. In other words, the multiple first internal electrode layers 118A, the multiple third internal electrode layers 118C, and the multiple second internal electrode layers 118B are located in this order from the first main surface 111 side to the second main surface 112 side in the stacking direction T.

[0052] When the base body 110 is viewed in the above cross-section, the multiple first internal electrode layers 118A have both ends 151A in the width direction W curved toward the second main surface 112. The curvature of each end 151A is, for example, 0.004 (1 / μm) or more and 0.02 (1 / μm) or less.

[0053] When the base body 110 is viewed in the above cross-section, the multiple second internal electrode layers 118B have both ends 151B in the width direction W curved toward the first main surface 111. The curvature of each end 151B is, for example, 0.004 (1 / μm) or more and 0.02 (1 / μm) or less.

[0054] When the base body 110 is viewed in the above cross-section, the multiple third internal electrode layers 118C extend in a substantially linear manner along the width direction W. Here, "extending in a substantially linear manner along the width direction W" means that the curvature of each end of the third internal electrode layer 118C in the width direction W is 0.001 (1 / μm) or less.

[0055] As shown in Figure 2, when the base body portion 110 is viewed in a cross-section extending in the stacking direction T and the length direction L at the center of the width direction W, the multiple first internal electrode layers 118A have ends on the side opposite to the draw-out portion in the length direction L of the opposing portion that are curved toward the second main surface 112. The curvature of the above ends of the first internal electrode layers 118A is, for example, 0.004 (1 / μm) or more and 0.02 (1 / μm) or less.

[0056] When the base body portion 110 is viewed in the above cross-section, the multiple second internal electrode layers 118B have ends on the side opposite to the lead-out portion in the longitudinal direction L of the opposing portion that are curved toward the first main surface 111. The curvature of the above ends of the second internal electrode layers 118B is, for example, 0.004 (1 / μm) or more and 0.02 (1 / μm) or less.

[0057] The number of second internal electrode layers 118B is greater than the number of first internal electrode layers 118A. Preferably, the number of second internal electrode layers 118B is 1.5 to 9 times the number of first internal electrode layers 118A. Preferably, the number of third internal electrode layers 118C is less than the number of multiple first internal electrode layers 118A. In this embodiment, the multiple internal electrode layers 118 have four first internal electrode layers 118A, seven second internal electrode layers 118B, and three third internal electrode layers 118C.

[0058] It is preferable that the curvature of both ends 151A of each of the plurality of first internal electrode layers 118A increases as it goes from the second main surface 112 side to the first main surface 111 side. It is preferable that the curvature of both ends 151B of each of the plurality of second internal electrode layers 118B increases as it goes from the first main surface 111 side to the second main surface 112 side. Note that it is not necessary for the curvature of all of the plurality of both ends 151A to satisfy the condition of "increasing as it goes from the second main surface 112 side to the first main surface 111 side", and it is preferable that the above condition is satisfied when viewed as a whole. The same applies to the plurality of both ends 151B.

[0059] When looking at the cross-section where the body part 110 extends in the stacking direction T and the width direction W at the central part in the length direction L, the curvature of both ends 151A of the first internal electrode layer 118A located closest to the first main surface 111 side among the plurality of first internal electrode layers 118A is larger than the curvature of both ends 151B of the second internal electrode layer 118B located closest to the second main surface 112 side among the plurality of second internal electrode layers 118B.

[0060] The above both ends of each internal electrode layer that curves as described above can be confirmed, for example, by polishing the body part 110 so that the W-T cross-section of the body part 110 at the central part in the length direction L is exposed, and observing the cross-section using an optical microscope or the like.

[0061] <B. Manufacturing Method of Multilayer Ceramic Capacitor> FIG. 7 is a flowchart showing a manufacturing method of a multilayer ceramic capacitor according to an embodiment. Next, a manufacturing method of the multilayer ceramic capacitor 100 according to the present embodiment will be described with reference to FIG. 7.

[0062] First, as shown in FIG. 7, a ceramic dielectric slurry is prepared (step S1). Specifically, a ceramic dielectric powder, an additive powder, a binder resin, a dissolving solution, etc. are dispersed and mixed. Thereby, a ceramic dielectric slurry is prepared.

[0063] The ceramic dielectric powder is, for example, perovskite dielectric particles such as BaTiO3, CaTiO3, SrTiO3, CaZrO3, or CaHfO3. The additive powder consists of, for example, at least one of Si compounds, Mg compounds, Mn compounds, Fe compounds, Cr compounds, Ni compounds, and Co compounds. As the binder resin, polyurethane resin, urea resin, melamine resin, epoxy resin, vinyl acetate resin, acrylic resin, or aqueous polymers such as polyvinyl alcohol (PVA) or polyvinyl butyral (PVB) can be used. These may be used individually or in mixtures of two or more. The ceramic dielectric slurry may be solvent-based or water-based. When the ceramic dielectric slurry is a water-based paint, the ceramic dielectric slurry is prepared by mixing a water-soluble binder and dispersant with dielectric raw materials dissolved in water.

[0064] Next, a ceramic dielectric sheet is formed (step S2). Specifically, the ceramic dielectric slurry is formed into a sheet on a carrier film using a die coater, gravure coater, or microgravure coater and then dried. This forms a ceramic dielectric sheet.

[0065] Next, a mother sheet is formed (step S3). Specifically, a conductive paste is applied to a ceramic dielectric sheet so as to have a predetermined pattern. This forms a mother sheet on the ceramic dielectric sheet with a predetermined internal electrode pattern. The conductive paste contains Ni powder, a solvent, a dispersant, and a binder, and is prepared to have a constant viscosity. PVA or PVB can be used as the binder. Screen printing, inkjet printing, or gravure printing can be used as methods for applying the conductive paste. In addition to the mother sheet with the internal electrode pattern, a ceramic dielectric sheet that has not undergone step S3 is also prepared.

[0066] Next, multiple mother sheets are stacked (step S4). A stacking apparatus mainly consisting of a head unit and a stage unit is used for this stacking.

[0067] The head unit has a flat holding surface for holding the mother sheet. The head unit is configured to move the mother sheet by moving it in a predetermined direction while holding the mother sheet on this holding surface. The method of holding the mother sheet by the head unit is not particularly limited, and the head unit may be configured to hold the mother sheet by means of suction or adhesive force, for example. The stage unit has a flat plate shape. Multiple mother sheets are sequentially stacked on the stage unit by the head unit.

[0068] First, a predetermined number of mother sheets, each consisting only of ceramic dielectric sheets and lacking an internal electrode pattern, are stacked on the stage. Then, a predetermined number of mother sheets with an internal electrode pattern are stacked on top of those. Finally, a predetermined number of mother sheets, each consisting only of ceramic dielectric sheets and lacking an internal electrode pattern, are stacked on top of those. This completes the mother sheet group.

[0069] As a predetermined number of mother sheets, each having an internal electrode pattern, are stacked, as the stacking process progresses, both ends of the internal electrode pattern on the already stacked mother sheets in the width direction W, and the end opposite to the draw-out side in the length direction L of the opposing portion, curve upward in the stacking direction T. This is because the rigidity of the mother sheet located below it is considerably low, and the downward pressure from the mother sheets being stacked on top of it is cumulatively applied to the mother sheet. The internal electrode pattern that curves in this way corresponds to the second internal electrode layer 118B described above. Here, among the internal electrode patterns corresponding to the second internal electrode layer 118B, the curvature of the curve at both ends of the lower internal electrode pattern is greater than the curvature of the curve at both ends of the upper internal electrode pattern. In other words, the curvature decreases as the stacking sequence progresses from earlier to later.

[0070] Thus, in the initial stages of the lamination process of a mother sheet with an internal electrode pattern, both ends of the internal electrode pattern in the width direction W of the mother sheet curve upward in the lamination direction T. However, as the lamination process progresses further, the internal electrode pattern of the laminated mother sheets extends substantially linearly along the width direction W without curving as described above. This is because the rigidity of the mother sheets located below the mother sheet increases considerably as they are pressed together. This internal electrode pattern extending substantially linearly along the width direction W corresponds to the third internal electrode layer 118C described above.

[0071] As the lamination process of the mother sheets, which are provided with internal electrode patterns, progresses further, both ends of the internal electrode pattern of the laminated mother sheets in the width direction W, and the end opposite to the lead-out side in the length direction L of the opposing part, curve downwards in the lamination direction T. This curved internal electrode pattern corresponds to the first internal electrode layer 118A described above. Here, among the internal electrode patterns corresponding to the first internal electrode layer 118A, the curvature of the curve at both ends of the upper internal electrode pattern is greater than the curvature of the curve at both ends of the lower internal electrode pattern. In other words, the curvature increases as the lamination process progresses from earlier to later.

[0072] Thus, at the end of the lamination process of the mother sheets with internal electrode patterns, the ends of the internal electrode patterns curve downward in the lamination direction T, causing the mother sheets to bond more firmly to each other through an anchoring effect. This effectively suppresses the delamination of the mother sheets.

[0073] In this embodiment, the number of internal electrode patterns corresponding to the second internal electrode layer 118B is increased to the number of internal electrode patterns corresponding to the first internal electrode layer 118A by appropriately adjusting the pressure applied by the head unit toward the stage unit when the mother sheet is placed on the stage unit, and / or the elastic modulus of the ceramic dielectric sheet and internal electrode pattern constituting the mother sheet.

[0074] Next, the mother sheets are pressed together to form a dielectric block (step S5). Specifically, the mother sheets are pressed together in the stacking direction by hydrostatic pressing or rigid pressing. This forms a dielectric block. At this time, the ceramic dielectric sheets are pressed at a predetermined temperature, causing them to adhere closely to each other. In addition, a ceramic dielectric sheet of a certain thickness is placed and pressed as the outermost layer in the stacking direction. This protects the dielectric sheet on which the internal electrode pattern is formed.

[0075] Next, the dielectric block is divided to form chips (step S6). Specifically, the dielectric block is divided into multiple chips by cutting, dicing, or laser cutting to form a matrix. When dividing the dielectric block, it may be heated and softened before division. When dividing the dielectric block, the corners and edges of the chips may be rounded by barrel polishing or the like.

[0076] Next, the chip is fired (step S7). Specifically, the heating of the chip causes the dielectric material and conductive material contained in the chip to be fired, forming the base body 110. The firing temperature is, for example, 900°C to 1300°C. The firing temperature is set appropriately in accordance with the dielectric material and conductive material.

[0077] Next, an external electrode is formed (step S8). Specifically, a paste containing a co-material that is a dielectric material while containing Ni as a main component is applied to both end faces of the body part 110. After the paste is applied, the body part 110 and the base electrode layer are integrally fired. After firing, plating is applied to the base electrode layer. Examples of the plating method include electrolytic plating.

[0078] In the case of the multilayer ceramic capacitor 100 manufactured as described above, when the body part 110 is viewed in cross-section P (see FIG. 3), the curvature of the first ridge line part 110a is smaller than the curvature of the second ridge line part 110b. From this relationship, it is possible to determine from which main surface side the lamination was started in the lamination process of the mother sheet provided with the internal electrode pattern of the multilayer ceramic capacitor 100. Further, when the body part 110 is viewed in cross-section Q (see FIG. 2), the curvature of the first ridge line part 110e on the end face side is smaller than the curvature of the second ridge line part 110f on the end face side. Also from this relationship, it is possible to determine from which main surface side the lamination was started in the lamination process of the mother sheet provided with the internal electrode pattern of the multilayer ceramic capacitor 100.

[0079] ​​​​​​​​​ In this regard, in this embodiment, as described above, the multilayer ceramic capacitor 100 is configured such that the number of second internal electrode layers 118B is greater than the number of first internal electrode layers 118A. In other words, the number of first internal electrode layers 118A is limited to being less than the number of second internal electrode layers 118B.

[0082] By configuring it in this way, a multilayer ceramic capacitor 100 can be made in which the occurrence of the aforementioned structural defects is suppressed.

[0083] Furthermore, in this embodiment, as described above, when viewing the base portion in a cross-section extending in the stacking direction T and width direction W at the central part in the length direction L (see Figures 3 and 6), the curvature of both ends 151A of the first internal electrode layer 118A located closest to the first main surface 111 among the plurality of first internal electrode layers 118A is greater than the curvature of both ends 151B of the second internal electrode layer 118B located closest to the second main surface 112 among the plurality of second internal electrode layers 118B. In this way, by making the curvature of both ends 151A located closest to the first main surface 111 to a considerable extent within the range where no structural defects occur, it is possible to effectively suppress the peeling of the mother sheet on which the internal electrode pattern is provided during the manufacturing process.

[0084] (Other forms, etc.) The shape, configuration, size, number, material, etc., of each part shown in the embodiments of the present invention described above can be modified in various ways, as long as they do not depart from the spirit of the present invention.

[0085] Furthermore, the characteristic configurations shown in the embodiments of the present invention described above can naturally be combined with each other without departing from the spirit of the present invention.

[0086] Thus, the embodiments disclosed herein are illustrative in all respects and not restrictive. The technical scope of the present invention is defined by the claims and includes all modifications within the meaning and scope of equivalents to the claims. [Explanation of Symbols]

[0087] 100 Multilayer ceramic capacitor, 110 Element body part, 110a First ridgeline part, 110b Second ridgeline part, 110c Third ridgeline part, 110d Fourth ridgeline part, 110e First ridgeline part on end face side, 110f Second ridgeline part on end face side, 110g End surface side third ridgeline section, 110h End surface side fourth ridgeline section, 111 First main surface, 112 Second main surface, 113 First side surface, 114 Second side surface, 115 First end surface, 116 Second end surface, 118 Internal electrode layer, 118a First layer, 118A First internal electrode layer, 118a1 First opposing section, 118a2 First drawer part, 118b Second layer, 118B Second internal electrode layer, 118b1 Second opposing part, 118b2 Second lead section, 118C third internal electrode layer, 119a first outer layer, 119b second outer layer, 119c inner layer, 120 first external electrode, 130 second external electrode, 151A both ends, 151B both ends, C inner layer section, L length direction, T stacking direction, W width direction.

Claims

1. A base body comprising a plurality of dielectric layers and a plurality of internal electrode layers stacked in the stacking direction, and having a first main surface and a second main surface facing the stacking direction, a first side surface and a second side surface facing the width direction perpendicular to the stacking direction, and a first end surface and a second end surface facing the length direction perpendicular to the stacking direction and the width direction, Each of the first and second end faces is provided with an external electrode connected to the plurality of internal electrode layers, When the base body is viewed in a cross-section extending in the stacking direction and the width direction at the central part in the length direction, the plurality of internal electrode layers have a plurality of first internal electrode layers whose ends in the width direction are curved toward the second main surface, and a plurality of second internal electrode layers located toward the second main surface than the plurality of first internal electrode layers, whose ends in the width direction are curved toward the first main surface, A multilayer ceramic capacitor in which the number of the plurality of second internal electrode layers is greater than the number of the plurality of first internal electrode layers.

2. The multilayer ceramic capacitor according to claim 1, wherein the thickness of each of the plurality of dielectric layers is 0.4 μm or more and 6.2 μm or less.

3. The multilayer ceramic capacitor according to claim 1 or 2, wherein, when the base portion is viewed in cross-section, the curvature of both ends in the width direction of the first internal electrode layer located furthest toward the first main surface among the plurality of first internal electrode layers is greater than the curvature of both ends in the width direction of the second internal electrode layer located furthest toward the second main surface among the plurality of second internal electrode layers.

4. When the base portion is viewed in cross-section, the plurality of internal electrode layers further comprises a plurality of third internal electrode layers located between the plurality of first internal electrode layers and the plurality of second internal electrode layers in the stacking direction, The multilayer ceramic capacitor according to any one of claims 1 to 3, wherein, when the base portion is viewed in the cross-section, the plurality of third internal electrode layers extend substantially linearly along the width direction.

5. The multilayer ceramic capacitor according to claim 4, wherein the number of the plurality of third internal electrode layers is less than the number of the plurality of first internal electrode layers.

6. The base portion includes a first ridge portion which is the part where the first side surface and the first main surface intersect, and a second ridge portion which is the part where the first side surface and the second main surface intersect. The multilayer ceramic capacitor according to any one of claims 1 to 5, wherein, when the base portion is viewed in cross-section, the curvature of the first ridge portion is smaller than the curvature of the second ridge portion.

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