Multilayer ceramic capacitor and circuit board

Abstract

A multilayer ceramic capacitor according to one aspect of the present invention is provided with: a rectangular parallelepiped-shaped main body having: a laminate in which ceramic layers and internal electrodes having a metal as a main component are alternately laminated; and a protective part that covers the surface of the laminate. And a plurality of terminal electrodes electrically connected to the internal electrodes, the plurality of terminal electrodes being disposed at least on a mounting surface, the mounting surface being a surface that faces a circuit board when the circuit board is mounted among the surfaces forming the surface of the main body, and the mounting surface being disposed in the vicinity of an end portion of each terminal electrode that faces another terminal electrode. The outer edge side of the slope part gradually rises towards the opposite side of the laminated body.

Description

Technical Field

[0001] The present invention relates to a laminated ceramic capacitor and a circuit board. Background Art

[0002] A wide variety of ceramic electronic components are used in high-frequency communication systems, such as mobile phones. These components are being demanded to be smaller and thinner, and research is also underway on miniaturization and thinning of multilayer ceramic capacitors.

[0003] Patent Document 1 discloses a thin, unbreakable multilayer ceramic capacitor in which the via-hole electrodes that electrically connect internal electrode layers to each other and to terminal electrodes have a structure with voids formed therein. In the multilayer ceramic capacitor disclosed in Patent Document 1, the terminal electrodes are formed on the flat upper surface of the element body.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2020-72263

[0007] Non-patent literature

[0008] Non-patent document 1: JAAhmar et al.,'Flex Cracking of Multilayer CeramicCapacitors: Experiments on Fracture Propagation,'2018 7th Electronic SystemIntegration Technology Conference(ESTC),Dresden,Germany,2018,pp.1-6 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] In multilayer ceramic capacitors, stress is sometimes applied in a direction that separates the terminal electrodes due to thermal shock from soldering during installation on a circuit board, flexural deformation of the circuit board after installation, and other factors. As reported in Non-Patent Document 1, this stress sometimes concentrates at the ends of the terminal electrodes and propagates into the main body, causing cracks. Thus, cracks generated in the main body often develop from the ends of the terminal electrodes toward the interior of the main body, causing short circuits due to the concentration of the electric field in the air layer generated within the cracks. Therefore, a multilayer ceramic capacitor is required that is less prone to cracking from the time of installation on the circuit board, through the handling of the installed circuit board, and until use.

[0011] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a multilayer ceramic capacitor capable of suppressing the occurrence of cracks during and after mounting on a circuit board, and a circuit board having the multilayer ceramic capacitor mounted thereon.

[0012] Technical solutions to technical problems

[0013] The inventors of the present invention have conducted various studies to solve the above-mentioned problems and have found that the above-mentioned purpose can be achieved by providing the mounting surface of the multilayer ceramic capacitor, i.e., the surface opposite to the circuit board when mounted on the circuit board, with a slope portion that gradually rises from the boundary between the mounting surface and the terminal electrode toward the exposed upper surface side of the terminal electrode, thereby completing the present invention.

[0014] That is, the first aspect of the present invention for solving the above-mentioned technical problems is a stacked ceramic capacitor, which includes: a rectangular main body, which has: a stacked body, which is alternately stacked with ceramic layers and internal electrodes mainly composed of metal; and a protective portion covering the surface of the above-mentioned stacked body; and a plurality of terminal electrodes electrically connected to the above-mentioned internal electrodes, which are arranged at least on the mounting surface, and the above-mentioned mounting surface is the surface of each surface forming the surface of the above-mentioned main body, which is opposite to the circuit board when the circuit board is installed, and the above-mentioned mounting surface has a slope portion on the outer edge side near the end of each terminal electrode opposite to the other terminal electrodes as it goes to the opposite side of the above-mentioned stacked body.

[0015] A second aspect of the present invention for solving the above-mentioned problems is a circuit board equipped with the multilayer ceramic capacitor according to the first aspect.

[0016] Effects of the Invention

[0017] According to the present invention, it is possible to provide a multilayer ceramic capacitor in which cracking is suppressed during and after mounting on a circuit board, and a circuit board having the multilayer ceramic capacitor mounted thereon. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a schematic diagram (perspective view) showing the structure of a multilayer ceramic capacitor according to the first embodiment of the present invention.

[0019] Figure 2 yes Figure 1 AA cross-section (LT cross-section) in.

[0020] Figure 3a It is a schematic diagram (LT cross-sectional view) showing a linear slope portion.

[0021] Figure 3b It is a schematic diagram (LT cross-sectional view) showing a curved slope portion.

[0022] Figure 4 This figure shows the procedure for drawing a picture using a microscope image when confirming whether there is an inclined portion on the mounting surface.

[0023] Figure 5 It is a schematic diagram (LT cross-sectional view) showing a mounting surface having a convex portion between slope portions.

[0024] Figure 6 It is a schematic diagram (LT cross-sectional view) showing the structure of a multilayer ceramic capacitor according to a second embodiment of the present invention.

[0025] Figure 7 It is a schematic diagram (perspective view) showing the structure of a multilayer ceramic capacitor according to a third embodiment of the present invention.

[0026] Description of Reference Numerals

[0027] 100, 200, 300 multilayer ceramic capacitors

[0028] 10 main body

[0029] 11 Mounting surface

[0030] 111 Slope

[0031] 112 convex part

[0032] 20-layer stack

[0033] 21 ceramic layers

[0034] 22 (22a, 22b) internal electrodes

[0035] 23 (23a, 23b) through-hole conductor

[0036] 30 Protection Department

[0037] 31 Covering

[0038] 32 Edge

[0039] 40 (40a, 40b) terminal electrodes

[0040] 50 (50a, 50b) outer conductor

[0041] 41 base conductor

[0042] 42 plated conductor. DETAILED DESCRIPTION

[0043] Hereinafter, the structure and effects of the present invention will be described in conjunction with the technical concept with reference to the accompanying drawings. However, the working mechanism includes speculation, and its accuracy does not limit the present invention.

[0044] [Multilayer Ceramic Capacitors]

[0045] <First embodiment>

[0046] One embodiment of the multilayer ceramic capacitor according to the first aspect of the present invention is shown as a first embodiment. Figure 1 and Figure 2 In the first embodiment, the multilayer ceramic capacitor 100 is in the shape of a rectangular parallelepiped and has a pair of faces orthogonal to three mutually orthogonal axes, namely, the L axis as the length direction, the W axis as the width direction, and the T axis as the height direction. The rectangular parallelepiped is not limited to a mathematically defined rectangular parallelepiped, as long as it is a shape that can be identified as a rectangular parallelepiped when observing the overall shape. Therefore, a rectangular parallelepiped with rounded edges and corners, a rectangular parallelepiped with curved edges, and a rectangular parallelepiped with a curved surface with a small curvature also conforms to the rectangular parallelepiped in the present disclosure. The dimensions of the ceramic capacitor 100 in the length (L) direction, the width (W) direction, and the height (T) direction can each independently take arbitrary values.

[0047] Examples of the dimensions of the multilayer ceramic capacitor 100 include an L-direction dimension of 200 μm to 2000 μm, a W-direction dimension of 100 μm to 2000 μm, a T-direction dimension of 30 μm to 220 μm, and a W / L ratio of 0.3 to 1.0. Preferably, the L-direction dimension is 400 μm to 1200 μm, the W-direction dimension is 400 μm to 1200 μm, the T-direction dimension is 40 μm to 150 μm, and the W / L ratio of 0.4 to 1.0 is less than 1.0. To minimize design constraints on the mounting circuit board, a T-direction dimension of 100 μm or less is more preferred.

[0048] The multilayer ceramic capacitor 100 according to the first embodiment is as follows Figure 2As shown in a schematic cross-sectional view in FIG, the main body 10 includes a laminate 20 having ceramic layers 21 and internal electrodes 22 composed mainly of metal alternately laminated in the T direction, and a protective portion 30 covering the surface of the laminate 20. The internal electrodes 22 include internal electrodes 22a of one polarity that are electrically connected to each other, and internal electrodes 22b of a different polarity from that of the internal electrodes 22a that are electrically connected to each other.

[0049] The method of electrically connecting the internal electrodes 22a and the internal electrodes 22b is not particularly limited. Figure 2 The figure shows a method of connection through through-hole conductors 23 (23a, 23b), which are arranged in the interior of the main body 10 so as to penetrate the ceramic layer 21 in the stacking direction of the stacked body 20, and at least one end reaches the surface of the protection portion 30 (covering portion 31) described later. However, as shown in the second embodiment described later, the internal electrodes can also be led out to the end surface of the main body and connected through external conductors. In addition, Figure 2 Although the illustrated multilayer ceramic capacitor 100 includes two through-hole conductors 23 , the number of through-hole conductors in the multilayer ceramic capacitor according to the first aspect of the present invention is not limited thereto.

[0050] Protective portion 30 is disposed on the surface of main body 10 to cover the surface of laminate 20. Protective portion 30 includes a covering portion 31 disposed on a surface perpendicular to the T direction and an edge portion 32 disposed on surfaces perpendicular to the W direction and the L direction.

[0051] The multilayer ceramic capacitor 100 of the first embodiment includes a plurality of terminal electrodes 40 (40a, 40b). These terminal electrodes 40 (40a, 40b) are arranged on at least the mounting surface 11, which faces the circuit board when mounted on the circuit board, of the surfaces forming the main body 10. These terminal electrodes 40 are electrically connected to the internal electrodes 22 (22a, 22b). The method for electrically connecting the terminal electrodes 40 (40a, 40b) to the internal electrodes 22 (22a, 22b) is not particularly limited. Figure 2 Although the connection is made via the through-hole conductors 23 (23a, 23b), the connection may be made via an external conductor as in the second embodiment described later. Figure 2 The illustrated multilayer ceramic capacitor 100 includes two terminal electrodes 40 , but the number of terminal electrodes in the multilayer ceramic capacitor according to the first aspect of the present invention is not limited thereto.

[0052] The multilayer ceramic capacitor 100 of the first embodiment has a mounting surface 11 having a slope 111 near the end facing the other of the terminal electrodes 40 ( 40 a , 40 b ) whose outer edge rises toward the side opposite to the laminate 20 .

[0053] The thickness of the main body 10 obtained by subtracting the thickness of the terminal electrodes 40 ( 40 a , 40 b ) from the T-direction dimension of the multilayer ceramic capacitor 100 is, for example, 20 μm to 200 μm, or preferably 30 μm to 180 μm.

[0054] Hereinafter, each component constituting the multilayer ceramic capacitor 100 according to the first embodiment will be described in detail.

[0055] (Ceramic layer)

[0056] The ceramic layer 21 is formed of ceramic. The composition of the ceramic is not particularly limited as long as it is a composition that forms a dense ceramic layer 21 by simultaneous firing with the internal electrode 22 described later, and can be appropriately selected according to the characteristics required of the multilayer ceramic capacitor. Examples of the composition of the ceramic include materials mainly composed of barium titanate (BaTiO3), materials mainly composed of strontium titanate (SrTiO3), and materials mainly composed of BaTiO3 having a perovskite structure. 1-x-y Ca x Sr y Ti 1-z Zr z Materials with O3 as the main component, etc. Ceramics can contain the above-mentioned main components and additive elements. Examples of additive elements include at least one selected from Mo, Nb, Ta, W, Mg, Mn, V, Cr and rare earth elements (Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb), and Co, Ni, Li, B, Na, K and Si. The additive elements can be contained in the form of elemental monomers or in the form of compounds represented by oxides, nitrides and carbides. In addition, the additive elements can exist in a state of solid solution in the above-mentioned main component, or they can form a different phase with the elements constituting the above-mentioned main component or other additive elements.

[0057] (Internal Electrode)

[0058] The internal electrodes 22 (22a, 22b) are primarily composed of metal. The type of metal is not particularly limited, and nickel (Ni), copper (Cu), palladium (Pd), platinum (Pt), silver (Ag), gold (Au), and alloys thereof may be used. Nickel (Ni) is preferably used as the primary component due to its high heat resistance, the ability to increase the firing temperature when simultaneously firing with the ceramic layer 21 to form a dense ceramic layer 21, and its relatively low cost. As used herein, the term "primary component element" refers to the element with the highest content expressed in atomic percentage (atom %).

[0059] The internal electrodes 22 ( 22 a , 22 b ) may contain, in addition to metal, ceramic particles having the same composition as that of the ceramic constituting the ceramic layer 21 , or a glass component.

[0060] (Protection Department)

[0061] Protective portion 30 protects ceramic layer 21 and internal electrodes 22. The material of protective portion 30 is not limited, as long as it has high electrical insulation and low permeability to degradation factors such as moisture. To ensure uniform shrinkage during firing during the manufacture of multilayer ceramic capacitor 100 and to alleviate internal stress within multilayer ceramic capacitor 100, it is preferable that the main component of protective portion 30 be the same as that of the ceramic forming ceramic layer 21.

[0062] (Through-hole conductor)

[0063] Like the internal electrodes 22 (22a, 22b), the through-hole conductors 23 (23a, 23b) are primarily composed of metal. Examples of usable metals include the same metals as those used for the internal electrodes 22 (22a, 22b) described above. The composition of the through-hole conductors may be different from that of the internal electrodes 22 (22a, 22b), but is preferably the same as that of the internal electrodes 22 (22a, 22b). By making the through-hole conductors (23a, 23b) and the internal electrodes 22 (22a, 22b) have the same composition, the shrinkage caused by firing during the manufacture of the multilayer ceramic capacitor 100 is uniform, thereby suppressing deformation. Furthermore, the resistivity of the conductive path of the multilayer ceramic capacitor 100 becomes uniform, thereby suppressing localized heat generation during use.

[0064] The diameter of the through-hole conductor 23 ( 23 a , 23 b ) is not particularly limited, but is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm, from the perspective of ensuring the capacitance of the multilayer ceramic capacitor 100 and reducing resistance to suppress heat generation during circuit driving.

[0065] (Terminal electrode)

[0066] The material of the terminal electrodes 40 (40a, 40b) is not limited as long as it is conductive. Examples of the material include metals such as nickel (Ni), copper (Cu), tin (Sn), palladium (Pd), platinum (Pt), silver (Ag), and gold (Au), alloys containing any of these as a main component element, and conductive resins.

[0067] The terminal electrodes 40 (40a, 40b) may also have a structure including a base conductor 41 in contact with the main body 10 and a plated conductor 42 formed on the surface of the base conductor 41. With such a structure, the terminal electrodes 40 (40a, 40b) can improve the bonding strength to the main body 10 by utilizing the base conductor 41, and can improve the solder wettability during circuit board mounting by utilizing the plated conductor 42.

[0068] Ni is an example of a material for the base conductor 41. The thickness of the base conductor 41 can be from 0.1 μm to 10 μm, preferably from 0.5 μm to 5 μm. The base conductor 41 is preferably arranged at a distance of 15 μm or more from the outer edge of the mounting surface 11, maintaining a gap between the terminal electrodes 40 ( 40 a , 40 b ) and the outer edge of the mounting surface 11 while allowing the plated conductor 42 to be formed with a sufficient thickness.

[0069] The plated conductor 42 may be formed of a single layer or multiple layers. When the plated conductor 42 is formed of multiple layers, the number of layers is preferably 2 or more and 4 or less. Examples of the material and structure of the plated conductor 42 include Cu, Ni, and Sn in that order. The thickness of the plated conductor 42 may be 1 μm or more and 20 μm or less, preferably 3 μm or more and 10 μm or less.

[0070] The area of ​​the terminal electrodes 40 (40a, 40b), that is, the area of ​​the terminal electrodes 40 (40a, 40b) when viewing the multilayer ceramic capacitor 100 from a direction perpendicular to the mounting surface, is not particularly limited. It can be large enough to facilitate mounting on a circuit board and small enough to prevent electrodes of different polarities from short-circuiting. The ratio of the total area of ​​the terminal electrodes 40 to the area of ​​the mounting surface 11 is preferably 0.2 to 0.9, and more preferably 0.3 to 0.8.

[0071] (Slope)

[0072] On the mounting surface 11, a slope portion 111 is formed so that the outer edge side gradually rises (rises) as it goes toward the opposite side of the stacked body 20, and is arranged near the end of the terminal electrode 40 (40a, 40b) opposite to the other terminal electrodes. Due to the presence of the slope 111, the thickness (T-direction dimension) of the main body 10 decreases smoothly from the outer edge side to the center side of the mounting surface 11. Due to this reduction in thickness, when tensile stress is generated between the terminal electrodes 40 (40a, 40b), the stress transmitted to the main body is applied not only to the vicinity of the end portions of the terminal electrodes 40 (40a, 40b) on the mounting surface 11, but also to the thinner center side, which can alleviate stress concentration and, as a result, suppress the occurrence of cracks.

[0073] In this specification, the term "near" the end of the terminal electrode conceptually refers to a region that exerts the aforementioned stress relaxation effect, and specifically, refers to a region within 50 μm from the end of the terminal electrode.

[0074] In this specification, the "slope portion" conceptually refers to a portion having a shape in which the height (position in the T direction) changes smoothly with respect to the position within the mounting surface 11, and is distinguished from a shape in which the height changes sharply, such as a "step". The shape of the cross section of the slope portion 111 parallel to the stacking direction of the stacked body 20 can be Figure 3a The straight line shown can also be Figure 3b If the slope of the slope portion 111 increases as it approaches its apex, it is preferable from the perspective of increasing the stress relaxation effect. The preferred lifting height h of the slope portion 111 is s Satisfy 0.1μm≤h s ≤10 μm. In addition, the length l of the slope portion 111 projected onto a plane perpendicular to the stacking direction of the stacked body 20 is preferably s Satisfy 1μm≤l s ≤100μm. By making the lifting height h s and length l s In the above-mentioned ranges, the above-mentioned stress relaxation effect becomes remarkable.

[0075] Here, whether the mounting surface 11 has a slope portion 111 near the end of the terminal electrode 40 (40a, 40b) opposite to the other terminal electrodes is judged according to the following steps. First, the stacked ceramic capacitor 100 is cut with a surface parallel to the stacking direction through the plurality of terminal electrodes 40 opposite to each other formed on the mounting surface 11 as an observation sample. The observation sample can also be prepared by grinding a surface orthogonal to the mounting surface until it reaches the plurality of terminal electrodes 40 opposite to each other formed on the mounting surface 11. Then, the observation sample is buried in the resin in a manner that the cut surface is exposed, and the cut surface is mirror-polished. Then, the mirror-polished cut surface is observed with an optical microscope or a scanning electron microscope (SEM) to obtain the following image: Figure 4The image shown is an image in which at least one terminal electrode 40 and the mounting surface 11 on one side of the other terminal electrode opposite thereto are arranged enter the same field of view. The observation magnification at this time is sufficient as long as the shape of the mounting surface 11 located near the end of the terminal electrode 40 can be grasped, and can be exemplified by 2000 times to 10000 times. Next, in the acquired image, the intersection point e of the end of the terminal electrode 40 opposite to the other terminal electrodes and the mounting surface is determined, and from point e in the direction horizontal to the mounting surface 11, two points are separated by a distance equivalent to an actual size of 50 μm, and line segments perpendicular to the horizontal direction are drawn respectively, and the intersection points of each line segment with the mounting surface 11 are set as e1 and e2 respectively. At this time, considering the possibility of the existence of the slope portion 111 near point e, the direction horizontal to the mounting surface 11 is determined based on the shape of the mounting surface 11 directly below the terminal electrode 40 located at a position sufficiently separated from point e (for example, a position with a distance of 60 μm or more from point e). Next, in the acquired image, draw a line segment H passing through the lowest point of the mounting surface 11 between point e1 and point e2 (the point at the bottom of the image) and horizontal to the mounting surface 11. b , and a line segment H passing through the highest point (the point located at the uppermost side in the image) and horizontal to the mounting surface 11 t , the intersection points of each line segment and the mounting surface 11 are set as point b and point t respectively. In addition, depending on the shape of the mounting surface 11, such as Figure 4 As shown, sometimes point b coincides with point e1, or sometimes point t coincides with point e2. However, in these cases, one point is considered to represent both. Next, since the mounting surface 11 in the image rises smoothly from point b to point t without any steps, it is determined that the slope 111 is located near the end of the terminal electrode 40 that faces the other terminal electrodes.

[0076] In addition, at this time, the line segment H b With line segment H t The distance is set as the lifting height h of the slope portion 111 s , and draw a line segment V through point b and perpendicular to the mounting surface 11 b , and a line segment V passing through point t and perpendicular to the mounting surface 11 t The distance is set to be the length l of the slope portion 111 projected onto the surface perpendicular to the stacking direction of the stacked body 20 s In addition, the lifting height h of the slope portion 111 is s Alternatively, the thickness of the main body 10 may be simply determined by measuring the thickness of the portion in contact with the terminal electrode 40 and the thickness of the portion not in contact with the terminal electrode 40 and taking the difference between them.

[0077] Furthermore, the above-mentioned steps determine whether the gradient of the slope portion 111 located near the end of the terminal electrode 40 facing the other terminal electrodes increases as it approaches its apex, and the following steps are performed. First, when the line segment V b Towards line segment V t Side separation distance l s Draw a vertical line V at the position of / 10 b’ The intersection point between it and the mounting surface 11 is set as b', and the vertical line V t Towards the vertical line V b Side separation distance l s Draw a vertical line V at the position of / 10 t’ , and its intersection with the mounting surface 11 is defined as t'. Next, linear approximation is performed on the shape of the mounting surface 11 between point b and point b', and the shape of the mounting surface 11 between point t and point t', respectively, to obtain line segments. Since the slope of the line segment derived from the shape of the mounting surface 11 between point t and point t' is greater than the slope of the line segment derived from the shape of the mounting surface 11 between point b and point b', it is determined that the slope of the slope portion 111 increases as it approaches the vertex.

[0078] When the terminal electrodes 40 (40a, 40b) include the base conductor 41 and the plated conductor 42, the slope portion 111 preferably does not contact the base electrode 41. The base electrode 41 is often formed by integral firing with the main body 10. In this case, the metal elements that form the base electrode 41 diffuse into the cover 31 via the mounting surface 11 during firing. In the slope portion 11, since the thickness of the cover 31 is reduced, diffusion of metal elements from the contacting base electrode 41 can easily lead to a decrease in insulation due to the metal elements reaching the internal electrodes 22 (22a, 22b). Therefore, by avoiding contact between the base electrode 41 and the slope portion 111, a decrease in insulation of the multilayer ceramic capacitor 100 can be suppressed.

[0079] When the slope portion 111 is not in contact with the base conductor 41, it is more preferable to arrange the plated conductor 42 on the slope portion 111. This increases the contact area between the slope portion 111 and the plated conductor, and can improve the bonding strength.

[0080] (Shape of the mounting surface other than the slope)

[0081] like Figure 5 As shown, when the lifting height of the slope is set to h s When the mounting surface 11 preferably has a height of 0.2h between the plurality of slope portions 111 s Above and 0.9h sThe following projections 112. As a result, when the multilayer ceramic capacitor 100 is mounted on a circuit board and resin is embedded therein, the bonding area between the mounting surface 11 and the resin is increased, and the bonding strength can be improved.

[0082] <Second embodiment>

[0083] Another embodiment (second embodiment) of the multilayer ceramic capacitor according to the first aspect of the present invention has a structure in which internal electrodes are electrically connected to each other via an external conductor. Figure 6 An example of a multilayer ceramic capacitor 200 according to the second embodiment is shown. In the multilayer ceramic capacitor 200, the internal electrodes extending to the end surface of the body 10 are electrically connected to each other via the external conductors 50 (50a, 50b), and the external conductors 50 (50a, 50b) are electrically connected to the terminal electrodes 40 (40a, 40b) arranged on the mounting surface 11. Figure 6 2 shows an example in which the outer conductors 50 ( 50 a , 50 b ) are formed on a pair of end surfaces facing each other, but the outer conductor may be formed on only one end surface.

[0084] <Third embodiment>

[0085] In another embodiment (third embodiment) of the multilayer ceramic capacitor according to the first aspect of the present invention, the number of terminal electrodes arranged on the mounting surface is four or more, and each terminal electrode has a different polarity from the nearest terminal electrode on the mounting surface. Figure 7 An example of a multilayer ceramic capacitor 300 according to a third embodiment is shown. Figure 7 , an example is shown in which the number of terminal electrodes 40 arranged on the mounting surface 11 is 4, but the number of terminal electrodes arranged on the mounting surface is not limited to this. The multilayer ceramic capacitor 300 has the following advantages: the direction of the current flowing in the through-hole conductors 23 (23a, 23b) electrically connected to each terminal electrode 40 (40a, 40b) is opposite to each other in the conductors 23 (23a, 23b) closest to each other, so the magnetic fields generated by the current cancel each other out, which can reduce the equivalent series inductance (ESL). The above-mentioned ESL reduction effect becomes significant when one spacing, i.e., the L-direction dimension, is set to Lμm and the other spacing, i.e., the W-direction dimension, is set to Wμm (where L≥W) in two sets of surfaces of the multilayer ceramic capacitor 300 that are parallel to the stacking direction of the stacked body and opposite to each other, when the ratio of W to L, i.e., W / L, is greater than 0.8 and less than 1, that is, when the mounting surface 11 has a shape that is close to a square.

[0086] [Method for Manufacturing Multilayer Ceramic Electronic Components]

[0087] The multilayer ceramic capacitor according to the first aspect of the present invention can be manufactured through the following process flow.

[0088] ((A) Preparation of ceramic powder)

[0089] First, prepare ceramic powder. Ceramic powder can be appropriately used from commercially available sources. In the case of homemade ceramic powder, various raw material powders containing the constituent elements are mixed at a predetermined ratio and pre-fired. When the various raw material powders are mixed at a predetermined ratio, various additives such as the aforementioned additive elements and sintering aids may be further added, and the aforementioned various additives may also be further added to the pre-fired powder.

[0090] ((B) Production of Green Sheet)

[0091] Next, the aforementioned ceramic powder is mixed with a binder and a dispersion medium to prepare a slurry, and the slurry is molded into a sheet to obtain a green sheet.

[0092] The binder used should maintain the shape of the green sheet and volatilize without leaving any carbon residue during the binder removal process before firing. Examples of usable binders include polyvinyl alcohol, polyvinyl butyral, cellulose, polyurethane, and vinyl acetate. The amount of binder used is not particularly limited, but since it is removed in subsequent steps, it is preferably reduced as much as possible to achieve the desired formability and shape retention from the perspective of reducing raw material costs.

[0093] As the dispersion medium, one that does not cause aggregation of the calcined powder and the binder and can be easily removed by volatilization after forming a green sheet as described below is used. Examples of usable dispersion media include water and alcohol solvents.

[0094] Ingredients such as dispersants, plasticizers and thickeners may be added to the slurry to adjust the slurry properties.

[0095] The method for mixing the mixed powder, the binder, and the dispersion medium is not particularly limited as long as the method can prevent the incorporation of impurities and uniformly mix the components.

[0096] As a method for forming the prepared slurry into a sheet shape to obtain a green sheet, a conventional method such as a doctor blade method and a die coating method can be used.

[0097] ((C) Formation of Internal Electrode Pattern)

[0098] Next, a metal-containing internal electrode pattern is formed on the green sheet. This internal electrode pattern can be formed by printing or applying an internal electrode paste in a predetermined pattern, or by forming a metal film in a predetermined pattern by vapor deposition or sputtering. The internal electrode pattern is formed with sufficient margins to ensure electrical insulation between non-contacting via conductor patterns to be formed later.

[0099] When forming the internal electrode pattern using an internal electrode paste, the internal electrode paste is obtained by mixing metal particles and a carrier using a three-roll mill. The internal electrode paste may contain glass frit and ceramic powder in addition to the above components.

[0100] The type and amount of the binder and solvent contained in the vehicle used are not limited and may be appropriately selected in consideration of the viscosity of the internal electrode paste, ease of handling, compatibility with the green sheet, and the like.

[0101] The internal electrode paste can be printed onto the green sheet using, for example, a screen mask having a predetermined internal electrode pattern formed thereon. During printing, the internal electrode paste can be printed while leaving a space that will serve as a peripheral portion when forming a multilayer ceramic capacitor.

[0102] ((D) Preparation of Green Laminated Body)

[0103] Next, a predetermined number of green sheets with internal electrode patterns are stacked and pressed together to form a green laminate. Stacking and pressing can be performed using conventional methods, such as heating the stacked green sheets while pressing them in the stacking direction and then thermally pressing them together with an adhesive. Alternatively, a mold with a convex surface can be pressed against the green sheets to form a concave portion on the surface that will serve as the mounting surface, thereby forming a slope that rises (gradually rises) from the concave portion.

[0104] During lamination and pressure bonding, additional green sheets may be added to the ends of the stacking direction to form the covering portion of the multilayer ceramic capacitor. In this case, the additional green sheets may have the same or different composition as the green sheets printed with the internal electrode pattern. To ensure consistent shrinkage during firing, the additional green sheets preferably have the same or similar composition as the green sheets with the internal electrode precursors.

[0105] ((E) Formation of Via-Hole Conductor Pattern)

[0106] In the case of manufacturing the laminated ceramic capacitor of the first embodiment, holes are then formed in the raw laminate, and the holes are filled with a conductor paste to form a through-hole conductor pattern. The holes can be formed by conventional methods such as a drill and a laser. Among them, from the perspective of being able to form a smooth processed surface, it is preferred to use a laser. When filling the holes with the conductor paste, conventional methods such as injection using a syringe and printing using a metal mask can be used. Among them, from the perspective of excellent filling properties for small-diameter holes, it is preferred to use a metal mask for printing. The components of the conductor paste can be the same as those of the internal electrode paste mentioned above, and the amount of each component can be determined in consideration of the filling properties of the holes.

[0107] ((F) Formation of Terminal Electrode Pattern)

[0108] Next, a terminal electrode pattern is formed on at least one of the surfaces (mounting surface) perpendicular to the stacking direction of the raw laminate. At this time, the raw sheet that becomes the covering portion when forming the laminated ceramic capacitor can also be pressed and bonded to the surface where the terminal electrode pattern is not formed in a manner that covers the through-hole conductor pattern. The terminal electrode pattern can be formed by a method of printing or applying a terminal electrode paste, or a method of forming a metal film by evaporation or sputtering. At this time, the terminal electrode pattern can be formed using a mask with a prescribed pattern, or it can be formed by temporarily forming a paste film or a metal film on the entire mounting surface of the raw laminate and then removing the portion other than the terminal electrode pattern. When removing the portion other than the terminal electrode pattern, a flat milling cutter, drum grinding, laser processing, etc. can be used. When removing the portion other than the terminal electrode pattern, a slope portion can also be formed by removing a portion of the surface of the raw laminate. When a terminal electrode paste is used in the formation of the terminal electrode pattern, the same paste as the internal electrode paste mentioned above can be used for its composition, and the mixing amount of each component can be determined in such a way as to obtain a uniform pattern according to a prescribed thickness.

[0109] ((G) Preparation of small pieces before firing)

[0110] Next, the green laminate is singulated into individual pieces in the shape of multilayer ceramic capacitors to obtain pre-fired small pieces. Singulation can be performed using conventional means such as a dicing machine or laser cutting machine. Alternatively, the green laminate can be singulated to form surfaces where the internal electrode precursors are exposed, and then these surfaces can be covered with a material for forming an edge portion to obtain pre-fired small pieces.

[0111] ((H) Removal of Adhesive)

[0112] Next, the obtained pre-fired small pieces are heated to volatilize and remove the binder. The heating conditions can be appropriately set taking into account the volatilization temperature and content of the binder. As an example, it can be kept at a temperature of 200°C to 500°C in a nitrogen (N2) atmosphere for 5 to 20 hours.

[0113] ((I) Firing of small pieces before firing)

[0114] Next, the pre-fired small piece from which the binder has been removed is heated to a predetermined temperature and fired. When setting the firing conditions, it is preferred to consider the sintering properties of the ceramic powder, and the heat resistance and oxidation resistance of the metals contained in the internal electrode pattern, the through-hole conductor pattern, and the terminal electrode pattern, respectively. As an example of firing conditions, there can be cited a temperature of 1100°C to 1400°C in a reducing atmosphere mixed with nitrogen (N2), hydrogen (H2), and water vapor (H2O) for 10 minutes to 2 hours. After firing, a reoxidation treatment can be performed in a nitrogen (N2) atmosphere or a low oxygen atmosphere at 600°C to 1000°C.

[0115] ((J) Formation of External Conductor and Terminal Electrode)

[0116] When manufacturing the multilayer ceramic capacitor of the second embodiment, the outer conductor is formed following the step (I) without performing the step (E), or the outer conductor and terminal electrodes are formed following the step (I) without performing the steps (E) and (F). Examples of methods for forming the outer conductor and terminal electrodes include a method of applying a conductive paste by printing or dipping and then sintering, and a method of forming a metal film by physical vapor deposition (PVD) such as evaporation.

[0117] The sintered body thus obtained may be used as a laminated ceramic capacitor as it is, or may be used as a laminated ceramic capacitor after forming a conductive layer on the surface of the terminal electrode pattern by plating.

[0118] [Circuit Board]

[0119] A circuit board according to a second aspect of the present invention is equipped with the multilayer ceramic capacitor according to the first aspect. This circuit board has excellent durability because the multilayer ceramic capacitor suppresses the occurrence of cracks.

[0120] The following technologies are also disclosed in this specification.

[0121] (Note 1)

[0122] A stacked ceramic capacitor comprising:

[0123] A rectangular parallelepiped body comprising: a laminated body in which ceramic layers and internal electrodes mainly composed of metal are alternately laminated; and a protective portion covering the surface of the laminated body; and

[0124] a plurality of terminal electrodes electrically connected to the internal electrodes, which are arranged at least on a mounting surface, wherein the mounting surface is a surface that faces the circuit board when the circuit board is mounted, among the surfaces forming the surface of the main body;

[0125] The mounting surface has a slope portion in which the outer edge side gradually rises toward the opposite side of the stacked body near an end portion of each terminal electrode facing the other terminal electrodes.

[0126] (Note 2)

[0127] The multilayer ceramic capacitor according to Supplementary Note 1, wherein:

[0128] The plurality of terminal electrodes include a base conductor in contact with a main body and a plated conductor formed on a surface of the base conductor, wherein the base conductor does not contact the slope portion.

[0129] (Note 3)

[0130] The multilayer ceramic capacitor according to Supplementary Note 2, wherein:

[0131] The plated conductor is disposed on the slope portion.

[0132] (Note 4)

[0133] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 3, wherein:

[0134] The slope of the slope portion increases as it approaches the top of the slope portion.

[0135] (Note 5)

[0136] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 4, wherein:

[0137] The lifting height h of the slope s Satisfy 0.1μm≤h s ≤10μm.

[0138] (Note 6)

[0139] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 5, wherein:

[0140] The length l of the slope portion projected onto a plane perpendicular to the stacking direction of the stacked body is s Satisfy 1μm≤l s ≤100μm.

[0141] (Note 7)

[0142] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 6, wherein:

[0143] When the lifting height of the slope portion is set to h s When the mounting surface has a height of 0.2h between the slope portionss Above and 0.9h s The following convex part.

[0144] (Note 8)

[0145] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 7, wherein:

[0146] The number of the plurality of terminal electrodes is four or more, and each terminal electrode has a polarity different from another terminal electrode closest to it in the mounting surface.

[0147] (Note 9)

[0148] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 8, wherein:

[0149] No electrodes are arranged on the surfaces of the main body that are opposite to the mounting surface.

[0150] The height, which is a dimension in a direction perpendicular to a region of the mounting surface other than the slope portion, is 100 μm or less.

[0151] (Note 10)

[0152] A circuit board having the multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 9 mounted thereon.

[0153] Industrial Application Possibilities

[0154] According to the present invention, a multilayer ceramic capacitor that suppresses cracking during and after mounting on a circuit board and a circuit board equipped with the multilayer ceramic capacitor can be provided. Such a multilayer ceramic capacitor and circuit component are useful in terms of excellent durability.

Claims

1. A multilayer ceramic capacitor, characterized in that: include: A rectangular parallelepiped body comprising: a laminated body in which ceramic layers and internal electrodes mainly composed of metal are alternately laminated; and a protective portion covering a surface of the laminated body; as well as a plurality of terminal electrodes electrically connected to the internal electrodes, the plurality of terminal electrodes being arranged at least on a mounting surface, the mounting surface being a surface that faces a circuit board when the circuit board is mounted, among the surfaces forming the surface of the main body; The mounting surface has a slope portion in which the outer edge side gradually rises toward the opposite side of the stacked body near an end portion of each terminal electrode facing the other terminal electrodes.

2. The multilayer ceramic capacitor according to claim 1, wherein: The plurality of terminal electrodes include a base conductor in contact with a main body and a plated conductor formed on a surface of the base conductor, wherein the base conductor does not contact the slope portion.

3. The multilayer ceramic capacitor according to claim 2, wherein: The plated conductor is disposed on the slope portion.

4. The multilayer ceramic capacitor according to any one of claims 1 to 3, wherein: The slope of the slope portion increases as it approaches the top of the slope portion.

5. The multilayer ceramic capacitor according to any one of claims 1 to 4, wherein: The lifting height h of the slope s Satisfy 0.1μm≤h s ≤10μm.

6. The multilayer ceramic capacitor according to any one of claims 1 to 5, wherein: The length l of the slope portion projected onto a plane perpendicular to the stacking direction of the stacked body is s Satisfy 1μm≤l s ≤100μm.

7. The multilayer ceramic capacitor according to any one of claims 1 to 6, wherein: When the lifting height of the slope portion is set to h s When the mounting surface has a height of 0.2h between the slope portions s Above and 0.9h s The following convex part.

8. The multilayer ceramic capacitor according to any one of claims 1 to 7, wherein: The number of the plurality of terminal electrodes is four or more, and each terminal electrode has a polarity different from another terminal electrode that is closest to the terminal electrode in the mounting surface.

9. The multilayer ceramic capacitor according to any one of claims 1 to 8, wherein: No electrodes are arranged on the opposing surface, which is the surface opposing the mounting surface, among the surfaces forming the surface of the main body. The height, which is a dimension in a direction perpendicular to a region of the mounting surface other than the slope portion, is 100 μm or less.

10. A circuit board, characterized in that: The multilayer ceramic capacitor according to any one of claims 1 to 9 is mounted thereon.

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