Multilayer ceramic capacitor and circuit board

Abstract

A multilayer ceramic capacitor according to one aspect of the present invention comprises: a rectangular parallelepiped-shaped main body having ceramic layers and internal electrodes 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 at least one end reaching the surface of the protection 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 forming a surface of the main body, the mounting surface facing the circuit board when the circuit board is mounted, the main body including: a capacitance forming portion that is a region in which the internal electrodes of different polarities of the internal electrodes overlap each other in a stacking direction; and an internal electrode portion facing portion formed by a region where internal electrodes of the same polarity of the internal electrodes overlap each other in the stacking direction and a via conductor disposed adjacent to the region, the thickness Tp of the internal electrode portion facing portion in the stacking direction being smaller than the maximum thickness T1 of the capacitance forming portion in the stacking direction.

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] In a laminated ceramic capacitor including through-hole electrodes (through-hole conductors) such as disclosed in Patent Document 1, there is a significant difference in thermal expansion coefficient between the through-hole conductors, which are primarily metal-based, and the ceramic layer in contact therewith. Consequently, during firing during the manufacturing process or when large temperature changes occur during use, cracks may form between the through-hole conductors and the ceramic layer due to the difference in expansion or contraction between the two. If these cracks extend and reach the interface between the internal electrode in contact with the ceramic layer and the through-hole conductor connected thereto, this can cause poor connection between the internal electrodes, leading to a decrease in electrostatic capacitance and becoming 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 a decrease in electrostatic capacitance, and a circuit board having the multilayer ceramic capacitor mounted thereon.

[0010] Technical solutions to technical problems

[0011] The present 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 via via-hole conductors, the above-mentioned object can be achieved by making the thickness of the body thinner near the via-hole conductors than in other parts, 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 main body in the shape of a rectangular parallelepiped, comprising: 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 in a stacking direction of the laminate, penetrating the ceramic layers, electrically connected to the internal electrodes, and having at least one end reaching the surface of 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, among the surfaces forming the surface of the main body, that faces the circuit board when the circuit board is mounted, the main body comprising: a capacitance forming portion, which is a region in which internal electrodes of different polarities overlap with each other in the stacking direction; and an internal electrode partial opposing portion, which is formed by a region in which internal electrodes of the same polarity overlap with each other in the stacking direction and the through-hole conductors arranged adjacent to the region, the thickness T of the internal electrode partial opposing portion in the stacking direction being p It is smaller than the maximum thickness T1 of the capacitance forming portion in the stacking direction.

[0013] 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.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to provide a thin multilayer ceramic capacitor in which a decrease in electrostatic capacitance 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 1 is a schematic diagram (LT cross-sectional view) showing an example of another shape of the internal electrode facing portion.

[0019] Figure 3B 1 is a schematic diagram (LT cross-sectional view) showing an example of another shape of the internal electrode facing portion.

[0020] Figure 4 This is used to explain the thickness T in the stacking direction of the internal electrode facing portion of the laminated ceramic capacitor. p A diagram showing a step smaller than the maximum thickness T1 of the capacitance-forming portion in the stacking direction.

[0021] Figure 5 It is a schematic diagram (LT cross-sectional view) showing the structure of a modified example of the multilayer ceramic capacitor according to the second embodiment of the present invention.

[0022] Figure 6 1 is a schematic diagram (LT cross-sectional view) showing the structure of a multilayer ceramic capacitor according to a third embodiment of the present invention.

[0023] Figure 7 It is a schematic diagram (perspective view) showing the structure of a multilayer ceramic capacitor according to a fourth embodiment of the present invention.

[0024] Description of Reference Numerals

[0025] 100, 100', 100", 200, 300, 400 multilayer ceramic capacitors

[0026] 10 main body

[0027] 11 Mounting surface

[0028] 12 Capacitor forming unit

[0029] 13 Internal electrode part facing part

[0030] 14 Lead-out surface

[0031] 20-layer stack

[0032] 21 ceramic layers

[0033] 22 (22a, 22b) internal electrodes

[0034] 23 (23a, 23b) through-hole conductor

[0035] 30 Protection Department

[0036] 31 Covering

[0037] 32 Edge

[0038] 40 (40a, 40b) terminal electrodes

[0039] 41 base conductor

[0040] 42 plated conductor

[0041] 50 (50a, 50b) external electrodes. DETAILED DESCRIPTION

[0042] 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.

[0043] [Multilayer Ceramic Capacitors]

[0044] <First embodiment>

[0045] 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.

[0046] 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.

[0047] The multilayer ceramic capacitor 100 according to the first embodiment is as follows Figure 2 As shown in a schematic cross-sectional view (LT cross section), the main body 10 includes a laminate 20 formed by alternating 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.

[0048] 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.

[0049] 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 at least one end reaches the surface of the protection portion 30 (cover 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. 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.

[0050] 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.

[0051] The main body 10 includes: a capacitor forming portion 12, which is a region where internal electrodes 22a and 22b of different polarities overlap in the stacking direction; and an internal electrode portion facing portion 13 formed by a region where internal electrodes 22a or internal electrodes 22b of the same polarity overlap in the stacking direction, and a through-hole conductor 23 arranged adjacent to the region. The thickness T of the internal electrode portion facing portion 13 in the stacking direction is p is smaller than the maximum thickness T1 of the capacitor forming portion 12 in the stacking direction. p <T1, the reduction of the electrostatic capacitance of the stacked ceramic capacitor 100 is suppressed. It is speculated that this is because the thickness of the main body 10 is thin, and the thickness of the internal electrode portion relative portion 13 is thinner than the capacitor forming portion 12. Therefore, in the internal electrode portion relative portion 13, the absolute amount of expansion or contraction in the stacking direction becomes smaller, and even if there is a difference in the amount of expansion or contraction due to the difference in thermal expansion coefficient between the through-hole conductor 23 (23a, 23b) and the ceramic layer 21, no cracks or crack extensions are generated at the interface between the two. In addition, Figure 2 , only the mounting surface 11 at the internal electrode portion facing portion 13 is recessed toward the laminate 20. However, the shape of the internal electrode portion facing portion 13 in the multilayer ceramic capacitor according to the first aspect of the present invention is not limited thereto. For example, the shape may be recessed as shown in FIG. Figure 3AAs in the case of the multilayer ceramic capacitor 100' shown in FIG. 1 , only the side facing the multilayer body 20 opposite to the mounting surface 11 is recessed, and a structure such as Figure 3B As in the multilayer ceramic capacitor 100 ″ shown in FIG. 1 , the mounting surface 11 and the surface facing thereto are recessed toward the multilayer body 20 .

[0052] Here, the thickness T of the internal electrode portion facing portion 13 in the stacking direction is p The case where the thickness is smaller than the maximum thickness T1 in the stacking direction of the capacitor forming portion 12 is determined by the following steps. First, the surface of the multilayer ceramic capacitor 100 perpendicular to the mounting surface is ground to expose the vicinity of the center of gravity of the through-hole conductor 23a. Grinding can also be performed on the multilayer ceramic capacitor 100 embedded in the resin. Next, an optical microscope or a scanning electron microscope (SEM) is used to observe the exposed ground surface of the through-hole conductor 23a to obtain the following information: Figure 4 The boundary between the through-hole conductor 23a and the ceramic layer 21, the mounting surface 11, and the surface opposite thereto are all in the same field of view. Figure 4 In order to make it easier to understand the position of the capacitor forming portion 12 and the internal electrode portion facing portion 13, the terminal electrode 40a is omitted. Next, in the acquired image, the internal electrode 22 (22a, 22b) is observed near the through-hole conductor 23a, and a line segment e is drawn that connects the end points of the internal electrode 22b on the through-hole conductor 23a side that are not connected to the through-hole conductor 23a. At this time, if the end points of the internal electrode 22b do not exist on a specific line segment, the line segment closest to each point is drawn as the line segment e. Depending on the configuration of the internal electrode 22 (22a, 22b), the line segment e may be drawn on both sides of the through-hole conductor 23a, or it may be drawn on only one side. Next, with the line segment e as the boundary, the area on the through-hole conductor 23a side where the internal electrode 22 (22a, 22b) is formed, including the through-hole conductor 23a, is set as the internal electrode portion facing portion 13. In addition, with line segment e as the boundary, the region where the internal electrode is formed on the opposite side of the through-hole conductor 23a is defined as the capacitor forming portion 12. Next, in the region that serves as the capacitor forming portion 12, the longest line segment among the line segments that are parallel to the line segment e that demarcates the boundary with the internal electrode portion opposing portion 13 and connects the mounting surface 11 and the surface opposing thereto is determined as line segment t1, and the value obtained by dividing the length of this line segment t1 by the magnification of the microscope image is defined as the maximum thickness T1 in the stacking direction of the capacitor forming portion 12. Next, at any location in the region that serves as the internal electrode portion opposing portion 13, a line segment t1 is drawn that is parallel to line segment t1 and connects the surface of the covering portion 31 that forms the mounting surface 11 and the surface of the covering portion 31 that forms the surface opposing thereto. p The value obtained by dividing the length of the line segment t1 by the magnification of the microscope image is defined as the thickness T of the internal electrode portion facing part 13 in the lamination direction at the arbitrary position.p . And, according to T p The relationship of <T1 holds true for the entire internal electrode portion facing portion 13, and it is determined that the thickness T of the internal electrode portion facing portion 13 in the lamination direction is p It is smaller than the maximum thickness T1 in the stacking direction of the capacitance forming portion 12. The above steps are performed in the vicinity of the via-hole conductor 23a, but can also be performed in the vicinity of the via-hole conductor 23b having a different polarity.

[0053] Regarding the internal electrode portion facing portion 13, the thickness T in the stacking direction is p When the minimum value of T1-T2 is set to T2, the value of T1-T2 is preferably 0.2 μm or more and 40 μm or less, more preferably 0.5 μm or more and 35 μm or less, and even more preferably 1 μm or more and 30 μm or less. By setting the value of T1-T2 to 0.2 μm or more, the aforementioned effect of suppressing the reduction in electrostatic capacitance becomes significant. On the other hand, by setting the value of T1-T2 to 40 μm or less, the reduction in mechanical strength caused by the reduction in the thickness of the main body 10 can be suppressed.

[0054] Regarding the internal electrode portion facing portion 13, the thickness T in the stacking direction is p When the minimum value of {(T1-T2) / T1}×100 is set to T2, the value of {(T1-T2) / T1}×100, that is, the percentage of the difference between the maximum thickness T1 of the capacitor forming portion 12 and the minimum thickness T2 of the internal electrode portion opposing portion 13 relative to the maximum thickness of the capacitor forming portion 12, is preferably 0.2% or more and 40% or less, more preferably 0.5% or more and 35% or less, and further preferably 1% or more and 30% or less. By setting the value of {(T1-T2) / T1}×100 to 0.2% or more, the above-mentioned effect of suppressing the reduction in electrostatic capacitance becomes significant. On the other hand, by setting the value of {(T1-T2) / T1}×100 to 40% or less, the reduction in mechanical strength caused by the reduction in the thickness of the main body 10 can be suppressed.

[0055] In the internal electrode portion facing portion 13, it is preferable that T pThe value increases as it approaches the capacitor forming portion 12 from the formation position of the through-hole conductor 23. In addition, at this time, it is more preferred that in the internal electrode portion relative portion 13, the shape of the mounting surface 11 or the surface opposite thereto increases in the amount of lifting as it approaches the capacitor forming portion 12 from the formation position of the through-hole conductor 23. It is speculated that this is because, in the surface having the above-mentioned shape, since the direction of the normal line varies depending on the position, it is possible to suppress stress concentration on a specific portion. If either the mounting surface 11 or the surface opposite thereto has the above-mentioned shape, the reduction in the mechanical strength of the main body 10 is significantly suppressed. However, from the perspective of suppressing the reduction in the mechanical strength of the main body 10, it is most preferred that both the mounting surface 11 and the surface opposite thereto have the above-mentioned shape.

[0056] 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.

[0057] Hereinafter, each component constituting the multilayer ceramic capacitor 100 according to the first embodiment will be described in detail.

[0058] (Ceramic layer)

[0059] 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.

[0060] (Internal Electrode)

[0061] 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 %).

[0062] 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.

[0063] (Protection Department)

[0064] 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.

[0065] (Through-hole conductor)

[0066] 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.

[0067] 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 recess 121 formed on the opposing surface 12 is effective in suppressing static charge.

[0068] The through-hole conductors 23 (23a, 23b) preferably have a recessed portion at their ends on the opposing surface 12 side, i.e., at the ends covered by the protective portion 30 (covering portion 31), in a cross section parallel to the stacking direction of the laminate 20. The recessed portion at the ends of the through-hole conductors 23 (23a, 23b) on the opposing surface 12 side is formed as a result of deformation of the cover-forming green sheet during the manufacturing process of the multilayer ceramic capacitor 100, described later. Therefore, the recessed portion at the ends of the through-hole conductors 23 (23a, 23b) on the opposing surface 12 side ensures high adhesion between the through-hole conductors 23 (23a, 23b) and the adjacent covering portion 31, ceramic layer 21, and internal electrodes 22 (22a, 22b), resulting in a multilayer ceramic capacitor 100 with high mechanical strength.

[0069] (Terminal electrode)

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] <Second embodiment>

[0075] The multilayer ceramic capacitor according to another embodiment (second embodiment) of the first aspect of the present invention may have a structure in which the outer edge of the laminate overlaps the outer edge of the through-hole conductor in a cross section passing through the through-hole conductor and parallel to the stacking direction. Figure 5 FIG. 2 shows an example of such a multilayer ceramic capacitor 200. In the multilayer ceramic capacitor 200, since the area of ​​the internal electrode portion facing portion 13 in a plane perpendicular to the stacking direction can be reduced and the area of ​​the capacitance forming portion 12 can be increased accordingly, there is an advantage in that a larger electrostatic capacitance can be obtained.

[0076] <Third embodiment>

[0077] In another embodiment (third 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 6 An example of a multilayer ceramic capacitor 300 according to a third embodiment is shown. Figure 6 In FIG, two surfaces facing each other are shown as an example of lead-out surfaces 14, but the number of lead-out surfaces is not limited to this. Figure 6 , an example is shown in which the terminal electrodes 40 (40a, 40b) extending to the lead surface 14 form the external electrodes 50 (50a, 50b), but the external electrodes 50 (50a, 50b) may also be formed separately from the terminal electrodes 40 (40a, 40b). Figure 6 In the stacking direction, there are regions at the left and right ends of the multilayer ceramic capacitor 300 where only a portion of the internal electrodes overlap. However, since these regions are not adjacent to the through-hole conductors, they do not correspond to the internal electrode partial facing portions referred to in the present invention. In the multilayer ceramic capacitor 300, 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), thereby reducing the current flowing through each of the through-hole conductors 23 (23a, 23b) and the external electrodes 50 (50a, 50b). This reduces heat generation during operation.

[0078] <Fourth embodiment>

[0079] In another embodiment (fourth 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 400 according to the third embodiment is shown. Figure 7The example in which the number of terminal electrodes 40 arranged on the mounting surface 11 is 4 is shown, but the number of terminal electrodes arranged on the mounting surface is not limited to this. The multilayer ceramic capacitor 400 has the following advantages: the direction of the current flowing in the through-hole conductor (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 one interval, i.e., the dimension in the L direction, is set to Lμm and the other interval, i.e., the dimension in the W direction, is set to Wμm (where L≥W) in two sets of surfaces of the multilayer ceramic capacitor 400 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 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 minimized 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 a sufficient margin to ensure electrical insulation between the non-contacting via conductor patterns formed later. This margin forms the opposing portion of the internal electrode portion in the fired body, described 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 the green sheets are pressed together to form a green laminate. The stacking and pressing can be performed using conventional methods, such as heating the stacked green sheets while pressing them in the stacking direction and hot pressing them under the action of an adhesive. In this case, by using a mold with a protrusion at a position corresponding to the opposing portion of the internal electrode portion for stamping, the thickness of the opposing portion of the internal electrode portion can be made thinner than the capacitor forming portion.

[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, holes are 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 using conventional methods such as a drill or 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, printing using a metal mask is preferred. 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 taking into account the filling properties of the holes.

[0101] ((F) Formation of Terminal Electrode Pattern)

[0102] 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 surface on which the terminal electrode pattern is not formed can also be crimped to form a green sheet that becomes a covering portion when forming a stacked ceramic capacitor 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 formed with a prescribed 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 and 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 prescribed thickness.

[0103] ((G) Preparation of small pieces before firing)

[0104] 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.

[0105] ((H) Removal of Adhesive)

[0106] 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.

[0107] ((I) Firing of small pieces before firing)

[0108] 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.

[0109] 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.

[0110] [Circuit Board]

[0111] A second aspect of the present invention includes a circuit board equipped with the multilayer ceramic capacitor of Embodiment 1. This circuit board has high reliability and can be installed in a narrow space because the multilayer ceramic capacitor is thin and can suppress a decrease in electrostatic capacitance.

[0112] This specification also discloses the following technologies.

[0113] (Note 1)

[0114] A stacked ceramic capacitor comprising:

[0115] 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, and having at least one end reaching the surface of the protective portion; and

[0116] 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.

[0117] The above entities include:

[0118] a capacitance forming portion in which internal electrodes of different polarities among the internal electrodes overlap each other in a lamination direction; and

[0119] an internal electrode portion facing portion formed by a region where the internal electrodes of the same polarity overlap each other in the stacking direction and the via-hole conductor arranged adjacent to the region;

[0120] The thickness T of the internal electrode portion in the stacking direction is p It is smaller than the maximum thickness T1 of the capacitance forming portion in the stacking direction.

[0121] (Note 2)

[0122] The multilayer ceramic capacitor according to Supplementary Note 1, wherein:

[0123] In the internal electrode portion facing portion, a distance between the mounting surface and a surface facing the mounting surface increases as the distance from the position where the through-hole conductor is formed approaches the capacitance forming portion.

[0124] (Note 3)

[0125] The multilayer ceramic capacitor according to Supplementary Note 1 or Supplementary Note 2, wherein:

[0126] The above T p When the minimum value of is set to T2, the value of T1-T2 is 0.2 μm or more and 40 μm or less.

[0127] (Note 4)

[0128] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 3, wherein:

[0129] The above T p When the minimum value of is T2, the percentage of the difference between T1 and T2 with respect to T1 {(T1-T2) / T1}×100 is 0.2% or more and 40% or less.

[0130] (Note 5)

[0131] The multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 4, wherein:

[0132] The dimension in the stacking direction is 100 μm or less.

[0133] (Note 6)

[0134] A circuit board having the multilayer ceramic capacitor according to any one of Supplementary Notes 1 to 5 mounted thereon.

[0135] Industrial Application Possibilities

[0136] According to the present invention, a thin multilayer ceramic capacitor can be provided that can suppress the reduction of electrostatic capacitance. Such a multilayer ceramic capacitor has high reliability and can be arranged in a narrow space, which is useful in that it has fewer restrictions on circuit board design.

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, and having at least one end reaching a surface of 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 subject includes: a capacitance forming portion, which is a region in which internal electrodes of different polarities among the internal electrodes overlap each other in a stacking direction; and an internal electrode portion facing portion formed by a region where the internal electrodes of the same polarity overlap each other in the stacking direction and the through-hole conductor arranged adjacent to the region; The thickness T of the internal electrode portion facing each other in the stacking direction p It is smaller than the maximum thickness T1 of the capacitance forming portion in the stacking direction.

2. The multilayer ceramic capacitor according to claim 1, wherein: The T of the inner electrode portion facing the p The value of increases as it moves from the formation position of the through-hole conductor to the capacitance forming portion.

3. The multilayer ceramic capacitor according to claim 1 or 2, wherein: The T p When the minimum value of is set to T2, the value of T1-T2 is 0.2 μm or more and 40 μm or less.

4. The multilayer ceramic capacitor according to any one of claims 1 to 3, wherein: The T p When the minimum value of is T2, the percentage of the difference between T1 and T2 with respect to T1 {(T1-T2) / T1}×100 is 0.2% or more and 40% or less.

5. The multilayer ceramic capacitor according to any one of claims 1 to 4, wherein: The dimension in the stacking direction is 100 μm or less.

6. A circuit board, characterized in that: The multilayer ceramic capacitor according to any one of claims 1 to 5 is mounted thereon.

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