Multilayer capacitor

Abstract

This multilayer capacitor (10) is provided with first and second capacitor elements (20, 30) which are stacked on each other and each have a positive electrode body (21, 31) and a negative electrode part (22, 32). The positive electrode body (21) of the first capacitor element (20) has a first portion (21a) that is disposed on one side in a first direction, and a second portion (21b) that is disposed on the other side in the first direction. The positive electrode body (31) of the second capacitor element (30) has a third portion (31a) that is disposed on one side in the first direction, and a fourth portion (31b) that is disposed on the other side in the first direction. The multilayer capacitor (10) is provided with: a first positive electrode terminal (51) that is electrically connected to the first portion (21a); a second positive electrode terminal (52) that is electrically connected to the third portion (31a); and a negative electrode terminal (60) that is electrically connected to the negative electrode parts (22, 32) of the first and second capacitor elements (20, 30). The second portion (21b) and the fourth portion (31b) are electrically connected to each other.

Description

Multilayer capacitors

[0001] The present disclosure relates to multilayer capacitors.

[0002] Conventionally, a surface-mount type multilayer capacitor known as a transmission line type noise filter has been known (see, for example, Patent Document 1). The multilayer capacitor in Patent Document 1 includes a box-shaped resin molded case base, a plurality of capacitor elements stacked with anodes at both ends and a cathode in the center, and a box-shaped case lid.

[0003] Japanese Patent Application Laid-Open No. 2009-076651

[0004] In recent years, the operating frequencies of electronic devices have become increasingly higher, and therefore further improvements in the performance of multilayer capacitors are desired.

[0005] One aspect of the present disclosure relates to a multilayer capacitor, comprising: a first capacitor element and a second capacitor element stacked on each other, each having an anode body, a cathode portion, and a dielectric layer interposed between the anode body and the cathode portion, the anode body of the first capacitor element having a first portion protruding from the cathode portion in one region in a first direction and a second portion protruding from the cathode portion in the other region in the first direction, the anode body of the second capacitor element having a third portion protruding from the cathode portion in one region in the first direction and a fourth portion protruding from the cathode portion in the other region in the first direction, a first anode terminal electrically connected to the first portion of the first capacitor element, a second anode terminal electrically connected to the third portion of the second capacitor element, and cathode terminals electrically connected to the cathode portions of the first capacitor element and the second capacitor element, the second portion and the fourth portion being electrically connected to each other.

[0006] According to the present disclosure, it is possible to provide a multilayer capacitor that reduces noise.

[0007] 1A and 1B are cross-sectional views schematically showing a multilayer capacitor according to a first embodiment, where (a) shows a cross-section along line IA-IA in FIG. 2A and (b) shows a cross-section along line IB-IB in FIG. 2A. 1B are cross-sectional views schematically showing a multilayer capacitor according to a first embodiment, where (a) shows a cross-section along line IIA-IIA in FIG. 1A and (b) shows a cross-section along line IIB-IIB in FIG. 1A. 1C are side cross-sectional views schematically showing capacitor elements, where (a) shows a capacitor element when the multilayer capacitor is a solid electrolytic capacitor, and (b) shows a capacitor element when the multilayer capacitor is a ceramic capacitor. 1C are perspective views schematically showing first and second capacitor elements and a cathode terminal according to a first embodiment. 1D are perspective views schematically showing first and second capacitor elements and a cathode terminal according to a second embodiment. 1E are perspective views schematically showing a multilayer capacitor according to a third embodiment, where (a) shows the first and second capacitor elements and (b) shows a state in which they are covered with an exterior body.

[0008] Embodiments of the multilayer capacitor according to the present disclosure will be described below using examples. However, the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be used as examples, but other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained.

[0009] The multilayer capacitor according to the present disclosure can be used as a transmission line component having a noise filter function. The multilayer capacitor according to the present disclosure includes a first capacitor element, a second capacitor element, a first anode terminal, a second anode terminal, and a cathode terminal. Note that there may be two or more anode terminals and one or more cathode terminals.

[0010] The first capacitor element has an anode body, a cathode portion, and a dielectric layer. The anode body may be, for example, sheet-like and have a shape (typically a rectangle) with two sides opposing each other in a first direction and two sides opposing each other in a second direction intersecting the first direction. The rectangle is preferably a rectangle with a short side and a long side. The anode body of the first capacitor element has a first portion protruding from the cathode portion in one region in the first direction and a second portion protruding from the cathode portion in the other region in the first direction. The first direction is preferably the longitudinal direction of the anode body. The first direction may be orthogonal to the stacking direction, and the second direction may be orthogonal to the first direction and the stacking direction. The one region in the first direction and the other region in the first direction refer to one region and the other region when the anode body is equally divided into two regions in the first direction (preferably the longitudinal direction) (the same applies to the anode body of the second capacitor element). When there are a plurality of first capacitor elements, the first portions adjacent to each other in the stacking direction may be electrically connected to each other, and the second portions adjacent to each other in the stacking direction may be electrically connected to each other.

[0011] The second capacitor element has an anode body, a cathode portion, and a dielectric layer. The anode body of the second capacitor element has a third portion protruding from the cathode portion in one region in the first direction and a fourth portion protruding from the cathode portion in the other region in the first direction. When there are multiple second capacitor elements, adjacent third portions in the stacking direction may be electrically connected to each other, and adjacent fourth portions in the stacking direction may be electrically connected to each other.

[0012] The first capacitor elements and the second capacitor elements are stacked on top of each other. The number of first capacitor elements and the number of second capacitor elements is not particularly limited. The stacking order of the first capacitor elements and the second capacitor elements is not particularly limited, regardless of the number of each capacitor element. When there are multiple first capacitor elements, the first portions are electrically connected to each other and the second portions are electrically connected to each other. When there are multiple second capacitor elements, the third portions are electrically connected to each other and the fourth portions are electrically connected to each other.

[0013] The anode bodies of the first and second capacitor elements may be made of a valve metal. Examples of valve metals that make up the anode bodies include aluminum, tantalum, niobium, and titanium. The anode bodies may be a valve metal foil or a sintered body of valve metal particles. Alternatively, the anode bodies of the first and second capacitor elements may be made of a metal other than a valve metal, such as a vapor-deposited metal. Examples of such metals include silver, nickel, and palladium.

[0014] The dielectric layers of the first and second capacitor elements may cover at least a portion of the surface of the anode body. The dielectric layers may be composed of an oxide (e.g., aluminum oxide) formed on the surface of the anode body by a liquid-phase method such as anodization, or a gas-phase method such as vapor deposition or atomic layer deposition. Alternatively, the dielectric layers may be composed of sintered particles of a dielectric ceramic composition. The dielectric ceramic composition may be primarily composed of barium titanate, for example. The dielectric layers are formed so as to be interposed at least between the anode body and the cathode portion.

[0015] The cathode portions of the first and second capacitor elements may have a solid electrolyte layer covering at least a portion of the surface of the dielectric layer and a cathode layer covering at least a portion of the surface of the solid electrolyte layer. Adjacent cathode portions in the stacking direction may be electrically connected to each other. The solid electrolyte layer may contain a conductive polymer. The solid electrolyte layer may further contain a dopant, as necessary. Alternatively, the cathode portion may be a metal layer made of silver, nickel, palladium, or the like, or may be a vapor-deposited metal.

[0016] Conductive polymers that can be used include known polymers used in solid electrolytic capacitors, such as π-conjugated conductive polymers. Examples of conductive polymers include polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, polyfuran, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polythiophene vinylene. Of these, polymers with a basic skeleton of polypyrrole, polythiophene, or polyaniline are preferred. The above polymers also include homopolymers, copolymers of two or more monomers, and derivatives thereof (e.g., substituted products having substituents). For example, polythiophenes include poly(3,4-ethylenedioxythiophene). Conductive polymers may be used alone or in combination.

[0017] The dopant may be, for example, at least one selected from the group consisting of low molecular weight anions and polyanions. Examples of low molecular weight anions include, but are not limited to, sulfate ions, nitrate ions, phosphate ions, borate ions, organic sulfonate ions, and carboxylate ions. Examples of dopants that generate organic sulfonate ions include benzenesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid. Examples of polyanions include polymeric polysulfonic acids and polymeric polycarboxylic acids. Examples of polymeric polysulfonic acids include polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacrylicsulfonic acid, and polymethacrylicsulfonic acid. Examples of polymeric polycarboxylic acids include polyacrylic acid and polymethacrylic acid. Examples of polyanions include polyestersulfonic acid and phenolsulfonic acid novolac resin. However, the polyanions are not limited to these.

[0018] The solid electrolyte layer may further contain, as necessary, known additives and known conductive materials other than conductive polymers, such as at least one selected from the group consisting of conductive inorganic materials such as manganese dioxide and TCNQ (7,7,8,8-tetracyanoquinodimethane) complex salts.

[0019] The cathode layer may be composed of a carbon layer formed on the surface of the solid electrolyte layer and a conductor layer formed on the surface of the carbon layer. The conductor layer may be composed of a silver paste. For example, the silver paste may be a composition containing silver particles and a resin component (binder resin). Although a thermoplastic resin may be used as the resin component, it is preferable to use a thermosetting resin such as an imide resin or an epoxy resin. The conductor layer may also be composed of a metal foil based on aluminum or copper.

[0020] The first anode terminal is electrically connected to the first portion of the first capacitor element. When multiple first capacitor elements are present, the first anode terminal may be electrically connected to the first portions of all of the first capacitor elements. The first anode terminal may be divided into two or more portions. The first anode terminal may be made of copper, a copper alloy, aluminum, or an aluminum alloy, and may be plated. Alternatively, the first anode terminal may have a conductive layer (e.g., a silver paste layer) containing conductive particles and a resin material and at least one plating layer (e.g., a Ni / Sn plating layer). The first anode terminal may be electrically connected to the first portion by crimping or by welding (e.g., laser welding or resistance welding). The first anode terminal may also be an end surface current collector exposed from the exterior housing.

[0021] The second anode terminal is electrically connected to the third portion of the second capacitor element. When multiple second capacitor elements are present, the second anode terminal may be electrically connected to the third portions of all of the second capacitor elements. The second anode terminal may be divided into two or more portions. The constituent material of the second anode terminal may be the same as or different from the constituent material of the first anode terminal. The second anode terminal may be electrically connected to the third portion by crimping or by welding (e.g., laser welding or resistance welding). The second anode terminal may also be an end surface current collector exposed from the exterior housing.

[0022] One of the first anode terminal and the second anode terminal may be disposed on one side in the second direction, and the other of the first anode terminal and the second anode terminal may be disposed on the other side in the second direction. The first anode terminal and the second anode terminal may be spaced apart from each other in the second direction. In the second direction, the length dimension of the first anode terminal may be 50% or less, or 45% or less, of the length dimension of the first capacitor element. In the second direction, the length dimension of the second anode terminal may be 50% or less, or 45% or less, of the length dimension of the second capacitor element.

[0023] The cathode terminal is electrically connected to the cathode portions of the first capacitor element and the second capacitor element. That is, the cathode terminal is electrically connected to all of the cathode portions. The cathode terminal may be electrically connected to the cathode portions via a conductive adhesive. The cathode terminal may be made of copper, a copper alloy, aluminum, or an aluminum alloy, and may be plated or formed of a vapor-deposited metal. The constituent material of the cathode terminal may be the same as or different from the constituent material of the first anode terminal. The cathode terminal may be divided into two or more parts. The cathode terminal may also be an end surface current collector exposed from the exterior body.

[0024] The second portion of the first capacitor element and the fourth portion of the second capacitor element are electrically connected to each other. This electrical connection may be achieved by any method. For example, the second portion and the fourth portion may be electrically connected to each other via a metal terminal, or the second portion and the fourth portion may be electrically connected to each other by cold compression bonding, laser welding, or the like.

[0025] The multilayer capacitor having the above-described configuration has a transmission line (or current path) in the following order (or in the reverse order): the first anode terminal, the first portion, the body portion of the first capacitor element (i.e., the portion of the first capacitor element excluding the first and second portions), the second portion, the fourth portion, the body portion of the second capacitor element (i.e., the portion of the second capacitor element excluding the third and fourth portions), the third portion, and the second anode terminal. When a current containing noise components flows through this transmission line, the noise components can be reduced by flowing into the cathode portions and cathode terminals of each capacitor element. The longer the transmission line, the greater the noise reduction function. Furthermore, the transmission line of the multilayer capacitor according to the present disclosure includes the body portion of the first capacitor element and the body portion of the second capacitor element in series, and is therefore longer than the transmission line of a conventional multilayer capacitor (i.e., a transmission line including only one body portion of a capacitor element). Therefore, the multilayer capacitor according to the present disclosure has a high noise reduction function relative to its size.

[0026] The multilayer capacitor according to the present disclosure may include a third anode terminal electrically connected to the second portion of the first capacitor element and the fourth portion of the second capacitor element. In this case, the multilayer capacitor is a four-terminal multilayer capacitor. In addition to the use as a multilayer capacitor having a long transmission line described above, such a four-terminal multilayer capacitor can also be used in a configuration in which the third anode terminal serves as an input terminal and each of the first and second anode terminals serves as an output terminal. The third anode terminal may be divided into two or more parts. The third anode terminal may be made of copper, a copper alloy, aluminum, or an aluminum alloy, and may be plated. The third anode terminal may be electrically connected to the second and fourth portions by crimping or by welding (e.g., laser welding or resistance welding). The third anode terminal may also be an end surface current collector exposed from the exterior housing.

[0027] The first portion may protrude in one direction in the first direction from the cathode portion of the first capacitor element. The second portion may protrude in the other direction in the first direction from the cathode portion of the first capacitor element. The third portion may protrude in one direction in the first direction from the cathode portion of the second capacitor element. The fourth portion may protrude in the other direction in the first direction from the cathode portion of the second capacitor element. In this case, the transmission line between the first portion and the second portion and the transmission line between the fourth portion and the third portion are lengthened. Therefore, by further lengthening the transmission line from the first portion to the third portion, the noise reduction performance of the multilayer capacitor can be further improved. At least one of the first portion and the second portion may protrude in the second direction (i.e., a direction perpendicular to the plane of the paper in FIG. 1 ) from the cathode portion of the first capacitor element, and at least one of the third portion and the fourth portion may protrude in the second direction from the cathode portion of the second capacitor element.

[0028] At least one of the first portion and the second portion may protrude in a second direction from the cathode portion of the first capacitor element. In this case, a large distance between the first portion and the second portion can be easily ensured, thereby increasing the degree of freedom in the arrangement of the first anode terminal and the second anode terminal electrically connected thereto. The second direction may intersect (preferably orthogonal to) the stacking direction and the first direction.

[0029] The cathode terminal may have a mounting surface portion disposed at one end of the first capacitor element and the second capacitor element in the stacking direction, and a sidewall portion rising continuously from the mounting surface portion and electrically connected to the side surfaces of each cathode portion of the first capacitor element and the second capacitor element. The mounting surface portion and the sidewall portion are integrally formed with each other. The mounting surface portion may be electrically connected to the cathode portion of the first or second capacitor element closest to it. The sidewall portion may be electrically connected to the side surfaces of each cathode portion via a conductive adhesive. The presence of such sidewall portions reduces impedance resulting from the resistance and inductance components of the cathode terminal, thereby improving the noise reduction function of the multilayer capacitor. Furthermore, because the sidewall portion is integrally formed with the mounting surface portion, a cathode terminal having a mounting surface portion and a sidewall portion can be easily fabricated, for example, by bending a predetermined frame blank.

[0030] The first capacitor element and the second capacitor element may have a conductive polymer layer covering at least a portion of the dielectric layer, or a ceramic layer constituting the dielectric layer. The conductive polymer layer may include the conductive polymer described above. The ceramic layer may include, for example, barium titanate and a minor component. The minor component may include at least one rare earth element selected from dysprosium, holmium, erbium, and yttrium, at least one rare earth element selected from manganese and vanadium, at least one rare earth element selected from silicon and aluminum, barium, and magnesium.

[0031] At least a plurality of second capacitor elements may be provided. In this case, the capacitance of the multilayer capacitor can be increased and the equivalent series resistance and impedance of the multilayer capacitor can be reduced. Note that a plurality of first capacitor elements and a plurality of second capacitor elements may be provided. The number of first capacitor elements and the number of second capacitor elements may be the same or different.

[0032] The first capacitor element and the plurality of second capacitor elements may be stacked alternately. In this case, the direction of the current flowing through the first capacitor element and the direction of the current flowing through the second capacitor element are opposite to each other, and therefore, by stacking the two capacitor elements alternately, the equivalent series inductance of the multilayer capacitor can be reduced.

[0033] The cathode terminal may have a mounting surface portion disposed at one end in the stacking direction of the first capacitor element and the second capacitor element. A plurality of second capacitor elements may be stacked together on the mounting surface portion side. The first capacitor element may be stacked on the opposite side of the mounting surface portion. The mounting surface portion may be electrically connected to the cathode portion of the second capacitor element closest to it. Here, the closer to the mounting surface portion, the higher the noise reduction function of the current flowing through the capacitor element. Therefore, when the multilayer capacitor having this configuration uses each of the first anode terminal and the second anode terminal as an output terminal, it is considered that an electrical circuit with relatively strict noise requirements will be connected to the output terminal corresponding to the second capacitor element stacked together on the mounting surface portion side. The cathode terminal may further have a sidewall portion extending continuously from the mounting surface portion and electrically connected to the side surfaces of the cathode portions of the first capacitor element and the second capacitor element.

[0034] As described above, according to the present disclosure, by increasing the length of the transmission line, it is possible to provide a multilayer capacitor having a high noise reduction function.

[0035] An example of a multilayer capacitor according to the present disclosure will be specifically described below with reference to the drawings. The components described above can be applied to the components of the example multilayer capacitor described below. The components of the example multilayer capacitor described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above-described embodiment. Of the components of the example multilayer capacitor described below, components that are not essential to the multilayer capacitor according to the present disclosure may be omitted. Note that the drawings shown below are schematic and do not accurately reflect the shapes and numbers of actual components.

[0036] Embodiment 1 Embodiment 1 of the present disclosure will be described. As shown in Figures 1 to 4, a multilayer capacitor 10 of this embodiment includes at least one (two in this example) first capacitor element 20, at least one (two in this example) second capacitor element 30, a first anode terminal 51, a second anode terminal 52, a third anode terminal 53, a cathode terminal 60, and an exterior body 70. In Figure 1, a side wall portion 60b, which will be described later, is indicated by a two-dot chain line.

[0037] The first capacitor element 20 has a first anode body 21, a first cathode portion 22, and a first dielectric layer 23. The first anode body 21 has a first portion 21a protruding from the first cathode portion 22 in one longitudinal region (the left side in FIG. 1 ) and a second portion 21b protruding from the first cathode portion 22 in the other longitudinal region (the right side in FIG. 1 ). The first capacitor element 20 further has a first insulating portion 24 provided between the first anode body 21 and the first cathode portion 22 to electrically insulate them from each other. The first anode body 21 is an example of an anode body. The first cathode portion 22 is an example of a cathode portion. The first dielectric layer 23 is an example of a dielectric layer. The longitudinal direction in FIG. 1 is an example of a first direction.

[0038] The second capacitor element 30 has a second anode body 31, a second cathode portion 32, and a second dielectric layer 33. The second anode body 31 has a third portion 31a protruding from the second cathode portion 32 in one longitudinal region (the left side in FIG. 1 ) and a fourth portion 31b protruding from the second cathode portion 32 in the other longitudinal region (the right side in FIG. 1 ). The second capacitor element 30 further has a second insulating portion 34 provided between the second anode body 31 and the second cathode portion 32 to electrically insulate them from each other. The second anode body 31 is an example of an anode body. The second cathode portion 32 is an example of a cathode portion. The second dielectric layer 33 is an example of a dielectric layer.

[0039] The first portion 21a protrudes from the first cathode portion 22 in one longitudinal direction (leftward in FIG. 1 ). The second portion 21b protrudes from the first cathode portion 22 in the other longitudinal direction (rightward in FIG. 1 ). The third portion 31a protrudes from the second cathode portion 32 in one longitudinal direction (leftward in FIG. 1 ). The fourth portion 31b protrudes from the second cathode portion 32 in the other longitudinal direction (rightward in FIG. 1 ). Note that the first to fourth portions 21a, 21b, 31a, 31b may protrude from the first or second cathode portion 22, 32 in the short direction (direction perpendicular to the plane of the paper in FIG. 1 ). The short direction is an example of the second direction.

[0040] The two first capacitor elements 20 and the two second capacitor elements 30 are stacked on top of each other. In this embodiment, the two first capacitor elements 20 and the two second capacitor elements 30 are stacked alternately.

[0041] The first anode body 21 and the second anode body 31 are each made of a foil of a valve metal (aluminum in this example), but are not limited to this. The first portions 21a of the two first anode bodies 21 are electrically connected to each other. The third portions 31a of the two second anode bodies 31 are electrically connected to each other. The first portions 21a and the third portions 31a are not directly connected to each other on one side in the longitudinal direction of the multilayer capacitor 10 (the left side in FIG. 1 ). In other words, the first portions 21a and the third portions 31a are spaced apart from each other in the short-side direction of the multilayer capacitor 10 (the direction perpendicular to the plane of the paper in FIG. 1 ).

[0042] 3( a), the first dielectric layer 23 covers at least a portion of the surface of the first anode body 21. The first dielectric layer 23 is made of an oxide (in this example, aluminum oxide) formed on the surface of the first anode body 21 that has been subjected to a surface roughening treatment, but is not limited to this. The second dielectric layer 33 covers at least a portion of the surface of the second anode body 31. The second dielectric layer 33 is made of an oxide (in this example, aluminum oxide) formed on the surface of the second anode body 31 that has been subjected to a surface roughening treatment, but is not limited to this.

[0043] The first cathode portion 22 includes a solid electrolyte layer (conductive polymer layer) covering at least a portion of the first dielectric layer 23 and a cathode layer covering at least a portion of the surface of the solid electrolyte layer. The second cathode portion 32 includes a solid electrolyte layer (conductive polymer layer) covering at least a portion of the second dielectric layer 33 and a cathode layer covering at least a portion of the surface of the solid electrolyte layer. Adjacent first cathode portions 22 and second cathode portions 32 in the stacking direction (the vertical direction in FIG. 1 ) are electrically connected to each other via conductive paste 40. Thus, all first cathode portions 22 and second cathode portions 32 are electrically connected to each other. The solid electrolyte layer includes a conductive polymer and a dopant. The cathode layer includes a carbon layer formed on the surface of the solid electrolyte layer and a conductor layer formed on the surface of the carbon layer. The conductor layer may be formed of silver paste. Alternatively, the conductor layer may be a metal foil based on aluminum or copper.

[0044] The multilayer capacitor 10 of this embodiment is a solid electrolytic capacitor including first and second capacitor elements 20, 30 of the type shown in Fig. 3(a). However, the present disclosure is not limited thereto, and the technical concept of the present disclosure can also be applied to a multilayer ceramic capacitor including first and second capacitor elements 20, 30 of the type shown in Fig. 3(b). Briefly describing the first and second capacitor elements 20, 30 in Fig. 3(b), the first and second anode bodies 21, 31 are composed of metal layers formed inside first and second dielectric layers 23, 33 (ceramic layers) containing barium titanate as a main component, and the first and second cathode portions 22, 32 are composed of metal layers formed on the surfaces of the first and second dielectric layers 23, 33. The first and second cathode portions 22, 32 protrude from the first and second anode bodies 21, 31 on both the front side and the back side in the direction perpendicular to the plane of the paper in Fig. 3(b).

[0045] The first anode terminal 51 is electrically connected to the first portion 21a of the first capacitor element 20. The first anode terminal 51 is made of, but is not limited to, a copper alloy. The first anode terminal 51 is electrically connected to the first portion 21a by crimping. Alternatively or in addition to crimping, the first anode terminal 51 may be welded to the first portion 21a.

[0046] The second anode terminal 52 is electrically connected to the third portion 31 a of the second capacitor element 30. The second anode terminal 52 is made of, but is not limited to, a copper alloy. The second anode terminal 52 is electrically connected to the third portion 31 a by crimping. Note that instead of or in addition to crimping, the second anode terminal 52 may be welded to the third portion 31 a.

[0047] The third anode terminal 53 is electrically connected to the second portion 21b of the first capacitor element 20 and the fourth portion 31b of the second capacitor element 30. This electrically connects the second portion 21b and the fourth portion 31b to each other. The third anode terminal 53 is made of, but is not limited to, a copper alloy. The third anode terminal 53 is electrically connected to the second portion 21b and the fourth portion 31b by crimping. Alternatively, or in addition to crimping, the third anode terminal 53 may be welded to the second portion 21b and the fourth portion 31b. This electrical connection may be achieved inside the multilayer capacitor 10 (or inside the exterior body 70) without going through the third anode terminal 53. Examples of such a method include cold pressure bonding and laser welding.

[0048] The cathode terminal 60 is electrically connected to the first cathode portion 22 and the second cathode portion 32 via, for example, a conductive adhesive (not shown). The cathode terminal 60 is made of a copper alloy, but is not limited to this.

[0049] The cathode terminal 60 has a mounting surface portion 60a disposed at one end (the lower end in FIG. 1 ) of the first and second capacitor elements 20, 30 in the stacking direction, and a sidewall portion 60b rising continuously from the mounting surface portion 60a and electrically connected to the side surfaces of the first cathode portion 22 and the second cathode portion 32. The mounting surface portion 60a is electrically connected to the second cathode portion 32 of the second capacitor element 30 closest thereto (the lowest in FIG. 1 ). The sidewall portion 60b is electrically connected to the side surfaces of each of the first cathode portion 22 and each of the second cathode portions 32 via a conductive adhesive (not shown). The cathode terminal 60 preferably has two or more sidewall portions 60b electrically connected to both side surfaces (the side surfaces on the front and rear sides of the page in FIG. 1 ) of each of the first cathode portion 22 and each of the second cathode portions 32.

[0050] The exterior body 70 covers the first and second capacitor elements 20, 30, the first to third anode terminals 51 to 53, and the cathode terminal 60 so that a portion of each of the first to third anode terminals 51 to 53 and the cathode terminal 60 is exposed. The exterior body 70 may be made of any insulating material, including, but not limited to, a resin or ceramic layer. The exposed portions of each of the first to third anode terminals 51 to 53 function as external terminals of the multilayer capacitor 10.

[0051] Second Embodiment A second embodiment of the present disclosure will be described. The multilayer capacitor 10 of this embodiment differs from the first embodiment in the stacking order of the first and second capacitor elements 20, 30. The following mainly describes the differences from the first embodiment.

[0052] As shown in Figure 5, in this embodiment, a plurality of (two in this example) second capacitor elements 30 are stacked together on the mounting surface portion 60a side of the cathode terminal 60 (the lower side in Figure 5), and a plurality of (two in this example) first capacitor elements 20 are stacked together on the opposite side of the mounting surface portion 60a (the upper side in Figure 5).

[0053] Third Embodiment A third embodiment of the present disclosure will be described. The multilayer capacitor 10 of this embodiment differs from the first embodiment in that it is a so-called end-face current collection type multilayer capacitor. The following mainly describes the differences from the first embodiment.

[0054] As shown in FIG. 6 , the multilayer capacitor 10 of this embodiment includes a plurality of cathode bodies C electrically connected to the cathode portions 22, 32 of the capacitor elements 20, 30 and projecting on both sides in the second direction between the cathode portions 22, 32. In each cathode body C, the portion projecting in one direction in the second direction and the portion projecting in the other direction are electrically connected to each other. Each cathode body C may be made of metal foil or vapor-deposited metal. The state shown in FIG. 6( a) is achieved by covering each component with an outer casing 70. Then, from the state shown in FIG. 6( b) , first to third anode terminals and cathode terminals (not shown) are formed, for example, by plating on the first to fourth portions 21 a, 21 b, 31 a, 31 b and the portions of each cathode body C exposed from the outer casing 70, thereby obtaining an end-collection type multilayer capacitor 10. In Figure 6, the two protrusions of each cathode body C are each marked with the symbol "C", but this is for ease of understanding, and each cathode body C is a single element extending in the second direction.

[0055] <<Notes>> The above description of the embodiment discloses the following techniques. (Technology 1) A multilayer capacitor comprising: a first capacitor element and a second capacitor element, each of which has an anode body, a cathode portion, and a dielectric layer interposed between the anode body and the cathode portion, and which are stacked on top of each other; the anode body of the first capacitor element has a first portion protruding from the cathode portion in one region in a first direction and a second portion protruding from the cathode portion in the other region in the first direction; the anode body of the second capacitor element has a third portion protruding from the cathode portion in one region in the first direction and a fourth portion protruding from the cathode portion in the other region in the first direction; a first anode terminal electrically connected to the first portion of the first capacitor element; a second anode terminal electrically connected to the third portion of the second capacitor element; and a cathode terminal electrically connected to the cathode portions of the first capacitor element and the second capacitor element; and the second portion and the fourth portion are electrically connected to each other. (Technology 2) The multilayer capacitor according to Technology 1, further comprising a third anode terminal electrically connected to the second portion of the first capacitor element and the fourth portion of the second capacitor element. (Technology 3) The multilayer capacitor according to Technology 1 or 2, wherein the first portion protrudes from the cathode portion of the first capacitor element in one direction in the first direction, the second portion protrudes from the cathode portion of the first capacitor element in the other direction in the first direction, the third portion protrudes from the cathode portion of the second capacitor element in one direction in the first direction, and the fourth portion protrudes from the cathode portion of the second capacitor element in the other direction in the first direction. (Technology 4) The multilayer capacitor according to Technology 1 or 2, wherein at least one of the first portion and the second portion protrudes from the cathode portion of the first capacitor element in a second direction.(Technology 5) The multilayer capacitor according to any one of Technologies 1 to 4, wherein the cathode terminal has: a mounting surface portion arranged at one end in the stacking direction of the first capacitor element and the second capacitor element; and a sidewall portion standing continuously from the mounting surface portion and electrically connected to a side surface of each of the cathode portions of the first capacitor element and the second capacitor element. (Technology 6) The multilayer capacitor according to any one of Technologies 1 to 5, wherein the first capacitor element and the second capacitor element have a conductive polymer layer covering at least a part of the dielectric layer or a ceramic layer constituting the dielectric layer. (Technology 7) The multilayer capacitor according to any one of Technologies 1 to 6, wherein at least a plurality of second capacitor elements are provided. (Technology 8) The multilayer capacitor according to Technology 7, wherein the first capacitor element and the plurality of second capacitor elements are alternately stacked. (Technology 9) The multilayer capacitor according to Technology 7, wherein the cathode terminal has a mounting surface portion disposed at one end in a stacking direction of the first capacitor element and the second capacitor element, the plurality of second capacitor elements are stacked together on the mounting surface portion side, and the first capacitor element is stacked on the opposite side of the mounting surface portion.

[0056] The characteristics of the multilayer capacitors of Examples and Comparative Examples were evaluated. Specifically, the multilayer capacitors of Examples were evaluated for the amount of noise suppression to the second anode terminal when a noise signal of 1 MHz or 100 MHz was input from the first anode terminal, and the multilayer capacitors of Comparative Examples were evaluated for the amount of noise suppression to one anode terminal when a noise signal of 1 MHz or 100 MHz was input from the other anode terminal.

[0057] Example: The multilayer capacitor of the type shown in the above-described embodiment 1 was evaluated. Three first capacitor elements and three second capacitor elements (six in total) were alternately stacked. The noise suppression amount was −108 dB for a 1 MHz noise signal and −136 dB for a 100 MHz noise signal.

[0058] Comparative Example: A multilayer capacitor was evaluated in which six capacitor elements of a different type from those in the example were stacked. The capacitor element had an anode body, a cathode portion, and a dielectric interposed between the two. The anode body had two protrusions protruding from the cathode portion on both sides in the longitudinal direction. The multilayer capacitor of the comparative example had an anode terminal electrically connected to one of the protrusions, and an anode terminal electrically connected to the other protrusion. Therefore, in the multilayer capacitor of the comparative example, noise signals flowed in the same direction in all six capacitor elements. The noise suppression level was −84 dB for a 1 MHz noise signal and −87 dB for a 100 MHz noise signal.

[0059] As described above, the multilayer capacitor of the example had a significantly higher noise suppression amount than the multilayer capacitor of the comparative example, demonstrating the superiority of the example.

[0060] The present invention can be embodied in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as limiting. The scope of the present invention is defined by the claims and is not limited to the text of the specification. Furthermore, all modifications and variations within the equivalent range of the claims are within the scope of the present invention.

[0061] This application claims priority from Japanese Patent Application No. 2024-005653, filed on January 17, 2024, the contents of which are incorporated herein by reference. In addition, all documents cited herein are specifically incorporated herein by reference in their entirety.

[0062] The present disclosure can be used for multilayer capacitors.

[0063] 10: Multilayer capacitor 20: First capacitor element 21: First anode body (anode body) 21a: First portion 21b: Second portion 22: First cathode portion (cathode portion) 23: First dielectric layer (dielectric layer) 24: First insulating portion 30: Second capacitor element 31: Second anode body (anode body) 31a: Third portion 31b: Fourth portion 32: Second cathode portion (cathode portion) 33: Second dielectric layer (dielectric layer) 34: Second insulating portion 40: Conductive paste 51: First anode terminal 52: Second anode terminal 53: Third anode terminal 60: Cathode terminal 60a: Mounting surface portion 60b: Side wall portion 70: Exterior body C: Cathode body

Claims

1. A multilayer capacitor comprising a first capacitor element and a second capacitor element, each having an anode body, a cathode portion, and a dielectric layer interposed between the anode body and the cathode portion, and being stacked on top of each other. The anode body of the first capacitor element has a first portion protruding from the cathode portion in one region in a first direction and a second portion protruding from the cathode portion in the other region in the first direction. The anode body of the second capacitor element has a third portion protruding from the cathode portion in one region in the first direction and a fourth portion protruding from the cathode portion in the other region in the first direction. The multilayer capacitor further comprises a first anode terminal electrically connected to the first portion of the first capacitor element, a second anode terminal electrically connected to the third portion of the second capacitor element, and a cathode terminal electrically connected to the cathode portions of the first capacitor element and the second capacitor element, wherein the second portion and the fourth portion are electrically connected to each other.

2. The multilayer capacitor according to claim 1, further comprising a third anode terminal electrically connected to the second portion of the first capacitor element and the fourth portion of the second capacitor element.

3. The multilayer capacitor according to claim 1 or 2, wherein the first portion protrudes from the cathode portion of the first capacitor element in one direction in the first direction, the second portion protrudes from the cathode portion of the first capacitor element in the other direction in the first direction, the third portion protrudes from the cathode portion of the second capacitor element in one direction in the first direction, and the fourth portion protrudes from the cathode portion of the second capacitor element in the other direction in the first direction.

4. The multilayer capacitor according to claim 1 or 2, wherein at least one of the first portion and the second portion protrudes from the cathode portion of the first capacitor element in a second direction.

5. The multilayer capacitor according to claim 1 or 2, wherein the cathode terminal has a mounting surface portion disposed at one end in the stacking direction of the first capacitor element and the second capacitor element, and a side wall portion that continuously rises from the mounting surface portion and is electrically connected to the side surfaces of the cathode portions of the first capacitor element and the second capacitor element.

6. The laminated capacitor according to claim 1 or 2, wherein the first capacitor element and the second capacitor element have a conductive polymer layer covering at least a part of the dielectric layer or a ceramic layer constituting the dielectric layer.

7. The laminated capacitor according to claim 1 or 2, wherein at least a plurality of the second capacitor elements are provided.

8. The laminated capacitor according to claim 7, wherein the first capacitor element and the plurality of second capacitor elements are alternately laminated.

9. The laminated capacitor according to claim 7, wherein the cathode terminal has a mounting surface portion disposed at one end in the lamination direction of the first capacitor element and the second capacitor element, the plurality of second capacitor elements are laminated together on the mounting surface portion side, and the first capacitor element is laminated on the side opposite to the mounting surface portion.

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