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 mainly composed of a metal are alternately laminated; a protective part covering the surface of the laminate; and a plurality of via-hole conductors which are disposed so as to penetrate the ceramic layer in the lamination direction of the laminate, are electrically connected to the internal electrodes, and have one end that reaches the surface of the protective part and the other end that is covered by the protective part. And a plurality of terminal electrodes electrically connected to the through-hole conductor, the plurality of terminal electrodes being disposed at least on a mounting surface, the mounting surface being a surface facing the circuit board when the circuit board is mounted among the surfaces forming the surface of the main body, the surface facing the mounting surface among the surfaces forming the surface of the main body being an opposing surface, the opposing surface being not provided with an electrode, and the terminal electrodes being electrically connected to the through-hole conductor. The through hole conductor has a protruding portion at a position where the side of the end portion of the through hole conductor covered by the protective portion is projected in the stacking direction of the stacked 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 and resistant laminated ceramic capacitor having a structure in which via-hole electrodes (via-hole electrodes) that electrically connect internal electrode layers and internal electrode layers to terminal electrodes have voids formed therein.

[0004] Prior art literature

[0005] Patent Literature

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

[0007] Technical problem to be solved by the invention

[0008] The multilayer ceramic capacitor disclosed in Patent Document 1 has terminal electrodes formed only on the upper surface of the relative upper and lower surfaces. In a multilayer ceramic capacitor of such a structure, the lower surface where the terminal electrodes are not formed does not have a protrusion caused by the external electrode, so the entire surface has a flat shape. Therefore, when the monolithic capacitor chips are handled in the manufacturing process, when the lower surface contacts the manufacturing equipment and jigs, other capacitor chips, etc., the static charge increases due to the increased contact area. As a result, poor transportation caused by pasting is likely to occur, and the yield rate during manufacturing is reduced, which becomes a problem. In addition, when the cover tape is peeled off from the carrier tape containing the capacitors, the charge increases due to the flat shape of the lower surface. Due to the increase in charge, the capacitor chips are pasted with the peeled cover tape, and the yield rate during installation is reduced, which also becomes a problem.

[0009] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a thin multilayer ceramic capacitor that suppresses the amount of static electricity generated during handling, and a circuit board having the multilayer ceramic capacitor mounted thereon.

[0010] Technical solutions to technical problems

[0011] The inventors have conducted various studies to solve the above-mentioned problems and have found that, in a multilayer ceramic capacitor in which internal electrodes are electrically connected to each other via through-hole conductors, the above-mentioned purpose can be achieved by forming the lower surface, i.e., the surface on which no terminal electrodes are formed, into a structure having protrusions at positions corresponding to the through-hole conductors, thereby completing the present invention.

[0012] That is, a first aspect of the present invention for solving the above-mentioned technical problems is a laminated ceramic capacitor comprising: a rectangular parallelepiped body having: a laminate in which ceramic layers and internal electrodes mainly composed of metal are alternately laminated; a protective portion covering the surface of the laminate; and a plurality of through-hole conductors arranged so as to penetrate the ceramic layers in the stacking direction of the laminate, electrically connected to the internal electrodes, with one end reaching the surface of the protective portion and the other end covered by the protective portion; and a plurality of terminal electrodes electrically connected to the through-hole conductors, arranged at least on a mounting surface, the mounting surface being a surface of each surface forming the surface of the body that faces a circuit board when the circuit board is mounted, and an opposing surface being a surface of each surface forming the surface of the body that faces the mounting surface, the opposing surface having no electrodes arranged thereon and having a convex portion at a position where the side of the end of the through-hole conductor covered by the protective portion is projected in the stacking direction of the laminate.

[0013] A second aspect of the present invention for solving the above-mentioned problems is a circuit board having the multilayer ceramic capacitor according to the first aspect mounted thereon.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to provide a thin multilayer ceramic capacitor in which the amount of static electricity generated during handling is suppressed, and a circuit board having the multilayer ceramic capacitor mounted thereon. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram (perspective view) showing the structure of a multilayer ceramic capacitor according to the first embodiment of the present invention.

[0017] Figure 2 yes Figure 1 AA cross-section (LT cross-section) in.

[0018] Figure 3a This figure is a diagram for explaining a procedure for determining whether or not the opposing surface of a multilayer ceramic capacitor has a convex portion at a position where the side of the end portion of a through-hole conductor covered by the protected portion is projected in the stacking direction of the multilayer body.

[0019] Figure 3bThis figure is used to explain the steps for determining the protrusion heights of the center and peripheral portions of the convex portion formed on the opposite surface of the stacked ceramic capacitor at the position where the side covered by the protected portion in the end portion of the through-hole conductor is projected in the stacking direction of the stacked body.

[0020] Figure 4 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.

[0021] Figure 5 It is a schematic diagram showing the structure of a multilayer ceramic capacitor according to a third embodiment of the present invention.

[0022] Description of Reference Numerals

[0023] 100, 200, 300 multilayer ceramic capacitors

[0024] 10 main body

[0025] 11 Mounting surface

[0026] 12 Opposite sides

[0027] 13 Lead-out surface

[0028] 121 convex part

[0029] 20-layer stack

[0030] 21 ceramic layers

[0031] 22 (22a, 22b) internal electrodes

[0032] 23 (23a, 23b) through-hole conductor

[0033] 30 Protection Department

[0034] 31 Covering

[0035] 32 Edge

[0036] 40 (40a, 40b) terminal electrodes

[0037] 41 base conductor

[0038] 42 plated conductor

[0039] 50 (50a, 50b) external electrodes. DETAILED DESCRIPTION

[0040] 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.

[0041] [Multilayer Ceramic Capacitors]

[0042] <First embodiment>

[0043] 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 addition, Figure 1 In such a manner that the convex portion formed on the opposite surface described later is easily observed, Figure 2 Compared to the above, the height direction (T-axis direction) is represented in reverse. The multilayer ceramic capacitor 100 involved in the first embodiment is in the shape of a rectangular parallelepiped, having 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.

[0044] 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.

[0045] The multilayer ceramic capacitor 100 according to the first embodiment is as follows Figure 2 As shown in a schematic cross-sectional view in (LT cross section), the main body 10 includes a laminate 20 formed by alternating layers of ceramic layers 21 and internal electrodes 22 composed mainly of metal 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.

[0046] Protective portion 30 is disposed on the surface of 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 edge portions 32 disposed on surfaces perpendicular to the W direction and the L direction.

[0047] The main body 10 has a plurality of through-hole conductors 23, which are arranged to penetrate the ceramic layers 21 in the stacking direction of the laminate 20, are electrically connected to the internal electrodes 22, and one end reaches the surface of the protection portion 30 (covering portion 31), and the other end is covered by the protection portion 30 (covering portion 31). The through-hole conductors 23 include a through-hole conductor 23a electrically connected to the internal electrode 22a and a through-hole conductor 23b electrically connected to the internal electrode 22b. In addition, Figure 1 and Figure 2 The illustrated multilayer ceramic capacitor 100 includes two through-hole conductors 23 , but the number of through-hole conductors in the multilayer ceramic capacitor according to the first aspect of the present invention is not limited thereto.

[0048] The multilayer ceramic capacitor 100 of the first embodiment has a plurality of terminal electrodes 40, which are arranged at least on the mounting surface 11, which is the surface facing the circuit board when the circuit board is mounted, among the surfaces forming the main body 10, and are electrically connected to the through-hole conductors 23 (23a, 23b). The terminal electrodes 40 include a terminal electrode 40a electrically connected to the through-hole conductor 23a and a terminal electrode 40b electrically connected to the through-hole conductor 23b. Figure 1 and 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.

[0049] On the other hand, no electrodes are arranged on the opposing surface 12, which is the surface opposing the mounting surface 11, of the surfaces forming the main body 10. Furthermore, the opposing surface 12 has a protrusion 121 at a position where the side of the end portion of the through-hole conductor 23 (23a, 23b) covered by the protective portion 30 (covering portion 31) is projected in the stacking direction of the laminate 20.

[0050] 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.

[0051] Hereinafter, each component constituting the multilayer ceramic capacitor 100 according to the first embodiment will be described in detail.

[0052] (Ceramic layer)

[0053] 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.

[0054] (Internal Electrode)

[0055] 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 %).

[0056] 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.

[0057] (Protection Department)

[0058] 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.

[0059] (Through-hole conductor)

[0060] 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.

[0061] The diameter of the through-hole conductors 23 (23a, 23b) is not particularly limited. However, from the perspective of ensuring the capacitance of the multilayer ceramic capacitor 100 while reducing resistance to suppress heat generation during circuit operation, the diameter is preferably 5 μm to 100 μm, and more preferably 10 μm to 50 μm. Furthermore, these preferred diameters are also preferred in terms of ensuring that the diameter of the protrusions 121 formed on the opposing surface 12 is effective in suppressing static charge.

[0062] The through-hole conductors 23 (23a, 23b) preferably have a convex portion protruding in the stacking direction at the end portion on the opposing surface 12 side in a cross section parallel to the stacking direction of the laminate 20, that is, at the end portion on the side covered by the protective portion 30 (covering portion 31). The convex portion at the end portion on the opposing surface 12 side of the through-hole conductors 23 (23a, 23b) is formed as a result of the conductive paste for forming the through-hole conductors not moving toward the mounting surface 11 but remaining there during the pressure bonding of the cover-forming green sheet forming the opposing surface 12 during the manufacturing process of the multilayer ceramic capacitor 100, which will be described later. This pushes the cover-forming green sheet back. Therefore, the structure of the convex portion at the end portion on the opposite surface 12 side of the through-hole conductor 23 (23a, 23b) indicates that the through-hole conductor 23 (23a, 23b) and the adjacent covering portion 31, ceramic layer 21 and internal electrode 22 (22a, 22b) have high adhesion, thereby obtaining a laminated ceramic capacitor 100 with high mechanical strength.

[0063] (Terminal electrode)

[0064] 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.

[0065] 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.

[0066] Ni can be exemplified as a material of the base conductor 41. The thickness of the base conductor 41 can be 0.1 μm or more and 10 μm or less, and preferably 0.5 μm or more and 5 μm or less.

[0067] 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.

[0068] (convex part)

[0069] The protrusion 121 formed on the opposite surface 12 is arranged at a position where the side covered by the protected portion 30 (covering portion 31) in the end portion of the through-hole conductor 23 (23a, 23b) is projected in the stacking direction of the stacked body 20. As a result, the amount of static electricity generated on the opposite surface 12 when handling the multilayer ceramic capacitor 100 can be reduced. It is speculated that this is due to the reduction in the area of ​​the region in contact with other parts or elements due to the presence of the protrusion 121. It is also speculated that in order to prevent short circuits, the through-hole conductor 23 is arranged at an appropriate interval from the end face of the multilayer ceramic capacitor 100 and other through-hole conductors 23. Therefore, by making the formation position of the protrusion 121 on the opposite surface 12 correspond to the through-hole conductor 23, and arranging the protrusions 121 at an appropriate interval from each other, it is also helpful to suppress the generation of static electricity. Furthermore, the protrusion 121 formed at the projected position of the end portion of the through-hole conductor 23 (23a, 23b) also indicates the position of the terminal electrode 40 (40a, 40b) formed on the mounting surface 11 side. Therefore, when the multilayer ceramic capacitor 100 is mounted on a circuit board, the pad and the terminal electrode 40 (40a, 40b) can also be aligned using the protrusion 121 as a mark.

[0070] Here, the following steps are used to determine whether the opposing surface 12 has a convex portion 121 at a position projected in the stacking direction of the laminate 20 on the side covered by the protected portion 30 (covering portion 31) in the end portion of the through-hole conductor 23 (23a, 23b). First, the terminal electrode 40 formed on the mounting surface 11 of the stacked ceramic capacitor 100 is removed to expose the through-hole conductor 23 on the mounting surface 11. As a method for removing the terminal electrode 40, grinding, acid dissolution, etc. can be used. Next, the stacked ceramic capacitor 100 is cut with a surface parallel to the stacking direction near the center of gravity of the through-hole conductor 23 exposed on the mounting surface to prepare an observation sample. The observation sample can also be prepared by grinding a surface orthogonal to the mounting surface to near the center of gravity of the through-hole conductor 23 exposed on the mounting surface. Next, the observation sample is buried in the resin in such a way that the cut surface is exposed, and the cut surface is mirror-polished. Next, the mirror-polished cut surface is observed with an optical microscope or a scanning electron microscope (SEM) to obtain Figure 3a An image is shown in which the opposing surface 12 and the through-hole conductor 23 are in the same field of view. Next, in the acquired image, line segments v1 and v2 are drawn, defining the two side surfaces of the through-hole conductor 23. These two line segments are then extended to the opposing surface 12. Next, the distance d between V1 and V2 is measured, with the intersection of line segment v1 and the opposing surface 12 defined as V1 and the intersection of line segment v2 and the opposing surface 12 defined as V2. Next, in the above image, a line segment c1 is drawn, parallel to line segment v1 and closer to the center of the through-hole conductor 23 than line segment v1, at a distance of 0.05d from line segment v1. A line segment c2 is drawn, parallel to line segment v2 and closer to the center of the through-hole conductor 23 than line segment v2, at a distance of 0.05d from line segment v2. The intersection of line segment c1 and the opposing surface 12 is defined as C1, and the intersection of line segment c2 and the opposing surface 12 is defined as C2. Next, in the above image, on the side opposite to point C1 relative to point V1, draw a line segment parallel to line segment v1 and at a distance of 0.05d from line segment v1, and define the intersection of this line segment and the opposite surface 12 as B. 11 , and on the side opposite to point C1 relative to point V1, draw a line segment parallel to line segment v1 and at a distance d from line segment v1, and set the intersection of this line segment and the opposite surface 12 as B 12 In addition, in the above image, on the side opposite to point C2 relative to point V2, draw a line segment parallel to line segment v2 and at a distance of 0.05d from line segment v2, and set the intersection of this line segment and the opposite surface 12 as B 21 , and on the side opposite to point C2 relative to V2, draw a line segment parallel to line segment v2 and at a distance d from line segment v2, and set the intersection of this line segment and the opposite surface 12 as B 22 . And, draw the point B on the opposite surface 12 11 and point B 12Between and point B 21 and B 22 The line segment b overlaps the regions between points C1 and C2 on the opposing surface 12. Furthermore, the region between points C1 and C2 on the opposing surface 12 is located on the opposite side of the through-hole conductor 23 relative to line segment b. Based on this, it is determined that the opposing surface 12 has a protrusion 121 at a position where the side of the through-hole conductor 23 (23a, 23b) covered by the protective portion 30 (covering portion 31) is projected in the stacking direction of the laminate 20. Furthermore, when drawing line segments v1, v2, and b, if the side surface of the through-hole conductor 23 or the opposing surface 12 observed in the image forms a curve or a broken line, a linear approximation of the curve or broken line is used as the line segment.

[0071] The number of the protrusions 121 formed on the opposing surface 12 is not limited, but is preferably formed at three or more locations, more preferably at four or more locations, from the viewpoint of improving the static charge suppression effect on the opposing surface 12 .

[0072] Convex portion 121 preferably has a circular or elliptical shape when viewed from a direction perpendicular to opposing surface 12. This can suppress the occurrence of cracks on opposing surface 12 when stress is applied to multilayer ceramic capacitor 100. This is presumably because stress is less likely to concentrate on specific locations around the periphery of convex portion 121.

[0073] The protrusion 121 preferably has a greater protrusion height at the center than at the periphery. This can further reduce the amount of static electricity generated on the opposite surface 12 when handling the multilayer ceramic capacitor 100. It is speculated that this is because the area of ​​the region in contact with other parts and components is reduced compared to the case where the protrusion height is constant. At this time, when the protrusion 121 has a shape in which the amount of elevation decreases as it approaches the center from the periphery, it is possible to significantly suppress the generation of cracks at the covering portion 31, and at the interface between the through-hole conductor 23 (23a, 23b) and the covering portion 31, at the interface between the through-hole conductor 23 (23a, 23b) and the internal electrode 22 (22a, 22b), and at the interface between the through-hole conductor 23 (23a, 23b) and the ceramic layer 21. This is preferred in this regard. It is speculated that this is because the direction of the normal to the surface of the protrusion 121 varies depending on the position, suppressing stress concentration at a specific location.

[0074] The protrusion height of the center portion of the convex portion 121 is preferably not less than 0.1 μm and not more than 10 μm, and more preferably not less than 0.2 μm and not more than 1.0 μm. By making the protrusion height of the center portion not less than 0.1 μm, the above-mentioned charge suppression effect becomes significant. On the other hand, by making the protrusion height of the center portion not more than 10 μm, it is possible to suppress the generation of cracks at the interface between the covering portion 12, the through-hole conductor 23 (23a, 23b) and the covering portion 31, the interface between the through-hole conductor 23 (23a, 23b) and the internal electrode 22 (22a, 22b), and the interface between the through-hole conductor 23 (23a, 23b) and the ceramic layer 21.

[0075] Here, the protrusion heights of the center and the periphery of the convex portion 121 are determined by the following steps. First, according to the above-mentioned determination step of whether the convex portion 121 is present on the opposing surface 12, a microscope image is obtained, and line segment v1, line segment v2, point V1, point V2, line segment c1, line segment c2, point C1, point C2, and line segment b are drawn in the image. Then, as shown in FIG. Figure 3b As shown, in the above image, draw the perpendicular bisector c of the line segment C1C2 c . Then, draw the line segment c c Parallel to line segment c c The two line segments c3 and c4 with a distance of 0.05d are drawn, and the intersection points with the opposite surface 12 are set as C3 and C4 respectively. Next, select any five points in the area between point C3 and point C4 on the opposite surface 12, and measure the distance between each point and the line segment b. And calculate the average value of the five measured values, and divide the average value by the magnification of the microscope image to obtain the value as the protrusion height of the center part of the convex part 121. Then, as Figure 3b As shown in the above image, lines parallel to line segment c1 and located closer to line segment c1 are drawn. c The line segment c5 is on the side of the line segment c1 and is 0.05d away from the line segment c1, and the line segment c2 is parallel to the line segment c2 and is closer to the line segment c2. c On the opposite side of the face, a line segment c6 is selected, which is 0.05d away from line segment c2. The intersection of line segment c5 and the opposing surface 12 is designated as C5, and the intersection of line segment c6 and the opposing surface 12 is designated as C6. Next, three arbitrary points are selected from the region between points C1 and C5 on the opposing surface 12, and three arbitrary points are selected from the region between points C2 and C6 on the opposing surface 12. The distances from each point to line segment b are measured. The average of the six measured values ​​is then calculated, and the value obtained by dividing this average by the magnification of the microscope image is used as the protrusion height of the peripheral edge of the protrusion 121.

[0076] <Second embodiment>

[0077] In another embodiment (second embodiment) of the multilayer ceramic capacitor of the first aspect of the present invention, the internal electrodes are led out to a surface perpendicular to the mounting surface, and external electrodes are arranged on the surface (lead-out surface) from which the internal electrodes are led out, and the internal electrodes are also electrically connected to each other via the external electrodes. Figure 4 An example of a multilayer ceramic capacitor 200 according to the second embodiment is shown. Figure 4 In FIG, two surfaces facing each other are shown as an example of lead-out surfaces 13, but the number of lead-out surfaces is not limited to this. Figure 4 2 shows an example in which the terminal electrodes 40 (40a, 40b) extending to the lead surface 13 form the external electrodes 50 (50a, 50b). However, the external electrodes 50 (50a, 50b) may also be formed separately from the terminal electrodes 40 (40a, 40b). In the multilayer ceramic capacitor 200, the current flowing through the internal electrodes 22 (22a, 22b) is divided between the through-hole conductors 23 (23a, 23b) and the external electrodes 50 (50a, 50b). This reduces the current flowing through each through-hole conductor 23 (23a, 23b) and the external electrodes 50 (50a, 50b). This reduces heat generation during operation.

[0078] <Third embodiment>

[0079] 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 5 An example of a multilayer ceramic capacitor 300 according to a third embodiment is shown. Figure 5The example in which the number of terminal electrodes 40 arranged on the mounting surface 11 is four is shown, but the number of terminal electrodes arranged on the mounting surface is not limited thereto. The multilayer ceramic capacitor 300 has the same number of through-hole conductors 23 (23a, 23b) as or greater than the number of terminal electrodes, and the same number of protrusions 121 as the through-hole conductors 23 (23a, 23b) formed on the opposite surface 12, so that the charging of the opposite surface 12 can be suppressed more effectively. In addition, the multilayer ceramic capacitor 300 has the following advantages: the direction of the current flowing in the through-hole conductors (not shown) electrically connected to each terminal electrode 40 (40a, 40b) is opposite in the conductors 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 effects become significant when, in two sets of surfaces of the stacked ceramic capacitor 300 that are parallel to the stacking direction of the stacked body and opposite to each other, one interval, i.e., the L-direction dimension, is set to Lμm and the other interval, i.e., the W-direction dimension, is set to Wμm (where L≥W), and 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 close to a square.

[0080] [Method for Manufacturing Multilayer Ceramic Electronic Components]

[0081] The multilayer ceramic capacitor according to the first aspect of the present invention can be manufactured through the following process flow.

[0082] ((A) Preparation of ceramic powder)

[0083] 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.

[0084] ((B) Production of Green Sheet)

[0085] 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.

[0086] 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.

[0087] 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.

[0088] Ingredients such as dispersants, plasticizers and thickeners may be added to the slurry to adjust the slurry properties.

[0089] 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.

[0090] 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.

[0091] ((C) Formation of Internal Electrode Pattern)

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] ((D) Preparation of Green Laminated Body)

[0097] Next, a predetermined number of green sheets with internal electrode patterns are stacked and pressure-bonded to form a green laminate. Conventional methods can be used for stacking and pressure-bonding, such as heating the stacked green sheets while pressing them in the stacking direction and then thermally pressing them with an adhesive.

[0098] 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.

[0099] ((E) Formation of Via-Hole Conductor Pattern)

[0100] Next, a hole is formed in the raw laminate, and a conductor paste is filled in the hole to form a through-hole conductor pattern. When filling the conductor paste, the conductor paste on the side that becomes the opposite surface when forming the stacked ceramic capacitor exceeds the surface height of the raw laminate and protrudes (protrudes). The hole can be formed by conventional methods such as a drill bit and a laser. Among them, from the viewpoint of being able to form a smooth processed surface, it is preferred to use a laser. When filling the hole with conductor paste, conventional methods such as injection using a syringe and printing using a metal mask can be used. Among them, from the aspect 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 use the same components as those of the internal electrode paste mentioned above, and the amount of each component can be determined by taking into account the filling properties of the hole.

[0101] ((F) Press-bonding of Cover Forming Green Sheet)

[0102] Next, a green sheet for forming a covering portion is pressed against the surface of the green laminate where the conductor paste protrudes.

[0103] ((G) Formation of Terminal Electrode Pattern)

[0104] Next, a terminal electrode pattern is formed on the surface opposite to the surface to which the cover forming raw sheet is crimped. The terminal electrode pattern can be formed by printing or applying a terminal electrode paste, or by forming a metal film by evaporation or sputtering. At this time, the terminal electrode pattern can be formed using a mask formed with a specified pattern, or 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 or a drum grinding can be used. 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 components, and the mixing amount of each component can be determined in such a way as to obtain a uniform pattern according to a specified thickness.

[0105] ((H) Preparation of small pieces before firing)

[0106] 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.

[0107] ((I) Removal of Adhesive)

[0108] 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.

[0109] ((J) Firing of small pieces before firing)

[0110] 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.

[0111] 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.

[0112] [Circuit Board]

[0113] A circuit board according to a second aspect of the present invention is equipped with the multilayer ceramic capacitor according to Embodiment 1. In this circuit board, since the multilayer ceramic capacitor is a thin capacitor having no electrodes on opposing surfaces, it can be installed even in a narrow space.

[0114] This specification also discloses the following technologies.

[0115] (Note 1)

[0116] A stacked ceramic capacitor comprising:

[0117] A rectangular parallelepiped body comprising: a laminated body in which ceramic layers and internal electrodes composed mainly of metal are alternately laminated; a protective portion covering the surface of the laminated body; and a plurality of through-hole conductors arranged to penetrate the ceramic layers in the stacking direction of the laminated body, electrically connected to the internal electrodes, with one end portion reaching the surface of the protective portion and the other end portion being covered by the protective portion; and

[0118] A plurality of terminal electrodes electrically connected to the through-hole conductors are arranged at least on a mounting surface, the mounting surface being a surface that faces the circuit board when the circuit board is mounted, among the surfaces forming the surface of the main body.

[0119] The surface of each surface forming the main body that faces the mounting surface is an opposing surface, has no electrode, and has a convex portion at a position where the side of the end portion of the through-hole conductor covered by the protective portion is projected in the stacking direction of the stacked body.

[0120] (Note 2)

[0121] The multilayer ceramic capacitor according to Supplementary Note 1, wherein:

[0122] The convex portions are present at three or more locations.

[0123] (Note 3)

[0124] The multilayer ceramic capacitor according to Supplementary Note 1 or Supplementary Note 2, wherein:

[0125] The convex portion has a circular or elliptical shape when viewed from a direction perpendicular to the opposing surface.

[0126] (Note 4)

[0127] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 3, wherein:

[0128] The end portion of the through-hole conductor on the opposite surface side in a cross section parallel to the stacking direction of the laminate has a convex portion that protrudes in the stacking direction.

[0129] (Note 5)

[0130] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 4, wherein:

[0131] The protrusion on the facing surface has a center portion with a greater protrusion height than a peripheral portion.

[0132] (Note 6)

[0133] The multilayer ceramic capacitor according to Supplementary Note 5, wherein:

[0134] The protrusion height of the central portion is not less than 0.1 μm and not more than 10 μm.

[0135] (Note 7)

[0136] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 6, wherein:

[0137] The dimension in the stacking direction is 100 μm or less.

[0138] (Note 8)

[0139] A circuit board having the multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 7 mounted thereon.

[0140] [Industrial Applicability]

[0141] According to the present invention, a thin multilayer ceramic capacitor can be provided that suppresses the amount of static electricity generated during handling. Such a multilayer ceramic capacitor can improve alignment accuracy when mounted on a circuit board, thereby achieving a high yield.

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 composed mainly of metal are alternately laminated; a protective portion covering a surface of the laminated body; and a plurality of through-hole conductors arranged to penetrate the ceramic layers in a stacking direction of the laminated body, electrically connected to the internal electrodes, with one end portion reaching the surface of the protective portion and the other end portion being covered by the protective portion; as well as A plurality of terminal electrodes electrically connected to the through-hole conductors are arranged at least on a mounting surface, which is a surface of the surface forming the main body that faces the circuit board when the circuit board is mounted. The opposing surface is a surface opposing the mounting surface among the surfaces forming the main body, has no electrode arranged thereon, and has a convex portion at a position where the side of the end portion of the through-hole conductor covered by the protective portion is projected in the stacking direction of the stacked body.

2. The multilayer ceramic capacitor according to claim 1, wherein: The convex portions exist at three or more locations.

3. The multilayer ceramic capacitor according to claim 1 or 2, wherein: The convex portion has a circular or elliptical shape when viewed from a direction perpendicular to the opposing surface.

4. The multilayer ceramic capacitor according to any one of claims 1 to 3, wherein: The end portion of the through-hole conductor on the opposite surface side in a cross section parallel to the stacking direction of the laminate has a convex portion that protrudes in the stacking direction.

5. The multilayer ceramic capacitor according to any one of claims 1 to 4, wherein: The convex portion on the opposing surface has a center portion with a greater protrusion height than a peripheral portion.

6. The multilayer ceramic capacitor according to claim 5, wherein: The protrusion height of the central portion is greater than or equal to 0.1 μm and less than or equal to 10 μm.

7. The multilayer ceramic capacitor according to any one of claims 1 to 6, wherein: The dimension in the stacking direction is 100 μm or less.

8. A circuit board, characterized in that: The multilayer ceramic capacitor according to any one of claims 1 to 7 is mounted thereon.

Images