Capacitor laminate and solid electrolytic capacitor

Abstract

A capacitor laminate (10) comprises a plurality of capacitor elements (11, 12, 13, 14) each of which is formed in a flat film shape and which are laminated such that flat film surfaces thereof overlap. The capacitor elements (11, 12, 13, 14) are provided with: positive electrode bodies (111, 121, 131, 141) that are each composed of a film-shaped valve action metal; dielectric layers (112, 122, 132, 142) that cover the positive electrode bodies (111, 121, 131, 141); conductive polymer layers (113, 123, 133, 143) that cover the dielectric layers (112, 122, 132, 142); and conductive layers (114, 124, 134, 144) that cover the conductive polymer layers (113, 123, 133, 143). The conductive layers (114, 124, 134, 144): are formed to have a prescribed area that does not include one end, in a first direction, of each of the positive electrode bodies (111, 121, 131, 141) but includes the other end; and each have a first end on the one end side and a second end on the other end side. The conductive layers (114, 124, 134, 144) and the conductive polymer layers (113, 123, 133, 143) have a first region (RE1) on the first end side and a second region (RE2) on the second end side in a flat surface on which the conductive layers (114, 124, 134, 144) are formed. The conductive polymer layers (113, 123, 133, 143) are provided with first protrusions that extend in a direction orthogonal to the first direction (DIR1) in the second region (RE2) and protrude toward the conductive layers. At least a portion of the first protrusions of adjacent ones of the plurality of capacitor elements overlap each other when viewed in the lamination direction. The adjacent ones of the plurality of capacitor elements (11, 12, 13, 14) are connected through the respective first protrusions.

Description

Laminated capacitors, solid electrolytic capacitors

[0001] The present invention relates to a solid electrolytic capacitor formed by stacking a plurality of capacitor elements.

[0002] Patent Document 1 describes a solid electrolytic capacitor, which includes a plurality of solid electrolytic capacitor elements.

[0003] Each of the plurality of solid electrolytic capacitor elements has a flat membrane shape and includes an anode portion of the flat membrane and a cathode portion covering the anode portion. Here, "flat membrane shape" refers to a solid shape having a predetermined thickness (e.g., about 0.1 mm) and area, and is also expressed as a plate shape or a foil shape. The plurality of solid electrolytic capacitor elements are stacked so that their cathode portions face each other and their flat membrane surfaces overlap.

[0004] A conductive adhesive containing silver (Ag) is placed between the cathode portions of adjacent solid electrolytic capacitor elements, and the cathode portions are electrically and physically connected by the conductive adhesive.

[0005] WO 2007 / 4505

[0006] However, in the conventional configuration as shown in Patent Document 1, the electrical and physical connection between adjacent cathode parts (between capacitor elements) relies on a silver-containing conductive adhesive, which can cause problems with reliability and characteristics.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to reduce reliability and performance problems that arise in the electrical and physical connections of multiple capacitor elements without relying on silver-containing conductive adhesives.

[0008] A laminated capacitor according to one embodiment of the present invention includes a plurality of capacitor elements each having a flat film shape and stacked so that the flat film surfaces overlap each other.

[0009] The capacitor element includes an anode body made of a film-like valve metal, a dielectric layer covering the anode body, a conductive polymer layer covering the dielectric layer, and a conductive layer covering the conductive polymer layer. The conductive layer is formed with a predetermined area that does not include one end of the anode body in a first direction but includes the other end, and has a first end on the one end side and a second end on the other end side.

[0010] The conductive layer and the conductive polymer layer have a first region on the first end side and a second region on the second end side in a plane on which the conductive layer is formed. The conductive polymer layer has a first protrusion extending in the second region in a direction perpendicular to the first direction and protruding toward the conductive layer.

[0011] The first protrusions of adjacent capacitor elements among the plurality of capacitor elements at least partially overlap when viewed in the stacking direction, and the adjacent capacitor elements among the plurality of capacitor elements are connected via their respective first protrusions.

[0012] In this configuration, the first convex portions of adjacent capacitor elements come into contact before the non-formed portions of the adjacent capacitor elements. When the capacitor elements are pressed in the stacking direction in this state, the first convex portions of the adjacent capacitor elements are crushed. As a result, the adjacent capacitor elements are reliably connected by their respective first convex portions over a predetermined area.

[0013] Therefore, adjacent capacitor elements among the plurality of capacitor elements are connected in a physically and electrically stable state without using a separate conductive adhesive.

[0014] According to the present invention, problems in reliability and characteristics that arise in the electrical and physical connections of a plurality of capacitor elements can be suppressed.

[0015] FIG. 1 is a side cross-sectional view of a solid electrolytic capacitor according to the first embodiment. FIG. 2 is an external perspective view of a capacitor element according to the first embodiment. FIG. 3(A) is a first plan view, FIG. 3(B) is a side cross-sectional view, and FIG. 3(C) is a second plan view of the capacitor element according to the first embodiment. FIG. 4 is an enlarged cross-sectional view of a portion of the capacitor element according to the first embodiment, including a convex portion. FIGS. 5(A) and 5(B) are enlarged cross-sectional views showing the location of the convex portion when multiple capacitor elements are stacked. FIGS. 6(A), 6(B), 6(C), 6(D), and 6(E) are plan views showing the state of the capacitor element according to the first embodiment in each manufacturing process. FIG. 7(A) is a plan view and FIG. 7(B) is a side cross-sectional view of a capacitor element according to a second embodiment. FIG. 8(A) is a plan view and FIG. 8(B) is a side cross-sectional view of a capacitor element according to a third embodiment. FIG. 9 is a side cross-sectional view of a solid electrolytic capacitor according to a fourth embodiment.

[0016] [First Embodiment] A solid electrolytic capacitor according to a first embodiment of the present invention will be described with reference to the drawings. In this embodiment, an aluminum solid electrolytic capacitor will be described as an example, but the configuration of this embodiment can be applied to any capacitor that includes multiple capacitor elements, each functioning individually as a capacitor, within a single housing (insulating resin body).

[0017] Fig. 1 is a side cross-sectional view of the solid electrolytic capacitor according to the first embodiment. Fig. 2 is an external perspective view of the capacitor element according to the first embodiment. Fig. 3(A) is a first plan view of the capacitor element according to the first embodiment, Fig. 3(B) is a side cross-sectional view, and Fig. 3(C) is a second plan view. Fig. 4 is an enlarged cross-sectional view of a portion including a protruding portion of the capacitor element according to the first embodiment.

[0018] (Outline of Solid Electrolytic Capacitor 1) As shown in FIG. 1, the solid electrolytic capacitor 1 includes a capacitor laminate 10, a first terminal electrode 20, a second terminal electrode 30, and an insulating resin body 40.

[0019] The laminated capacitor 10 includes a plurality of capacitor elements 11-14 (capacitor element 11, capacitor element 12, capacitor element 13, and capacitor element 14). In this embodiment, the number of capacitor elements constituting the laminated capacitor 10 is four, but the number of capacitor elements may be any number as long as it is plural.

[0020] (Capacitor elements 11-14) The multiple capacitor elements 11-14 have the same configuration in terms of the configuration in which they function as capacitors. Here, the configuration of the multiple capacitor elements 11-14 will be described, using capacitor element 12 as a representative, with reference to Figures 2, 3(A), 3(B), 3(C), and 4.

[0021] The capacitor element 12 includes an anode body 121 , a dielectric layer 122 , a conductive polymer layer 123 , and a conductive layer 124 .

[0022] Anode body 121 is a rectangular flat membrane in a plan view. Anode body 121 has main surfaces 121F1 and 121F2 that are parallel to first and second directions DIR1 and DIR2 that are perpendicular to each other. One end of anode body 121 in first direction DIR1 is one end 121EL1, and the other end is the other end 121EL2. The area and other parameters of anode body 121 are set based on the capacitance achieved by capacitor element 12.

[0023] The anode body 121 is made of, for example, a metal such as aluminum, tantalum, niobium, titanium, zirconium, magnesium, or silicon, or an alloy containing any of these metals. The anode body 121 is preferably made of aluminum or an aluminum alloy. The anode body 121 may be made of any valve metal that exhibits so-called valve action.

[0024] Although detailed illustration is omitted, anode body 121 is composed of multiple layers in the thickness direction (DIRH direction). Specifically, anode body 121 is composed of a core portion, a first surface layer portion, and a second surface layer portion. The first surface layer portion, core portion, and second surface layer portion are arranged in this order (first surface layer portion, core portion, second surface layer portion) from main surface 121F1 toward main surface 121F2 of anode body 121.

[0025] The core portion is not porous. The first surface layer portion and the second surface layer portion are porous. The thickness of the core portion is preferably 5 μm or more and 100 μm or less. The thicknesses of the first surface layer portion and the second surface layer portion are preferably 5 μm or more and 200 μm or less, respectively. The porous body is formed by communicating cavities having a diameter (or the maximum dimension determining the volume) of, for example, 0.5 μm or less, and the maximum dimension of the area portion opening to the main surface 12F1 and the main surface 12F2 is 0.5 μm or less.

[0026] Dielectric layer 122 covers anode body 121. More specifically, dielectric layer 122 covers main surface 12F1 and main surface 12F2 of anode body 121. More specifically, dielectric layer 122 covers the surface of the porous body that constitutes the first surface layer portion of anode body 121 and the surface of the porous body that constitutes the second surface layer portion. Dielectric layer 122 also covers both side surfaces and the end face of other end 121EL2 of anode body 121.

[0027] Dielectric layer 122 is preferably made of an oxide film of anode body 121. When aluminum foil is used for anode body 121, dielectric layer 122 is formed by oxidizing the anode body 121 in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or a sodium salt or ammonium salt thereof. The thickness of dielectric layer 122 is preferably 1 nm or more and 100 nm or less.

[0028] Conductive polymer layer 123 covers the outer surface of dielectric layer 122 opposite the surface that abuts anode body 121. Conductive polymer layer 123 has first surface 123F1 as the surface of conductive polymer layer 123 on the main surface 121F1 side of anode body 121. Conductive polymer layer 123 has second surface 123F2 as the surface of conductive polymer layer 123 on the main surface 121F2 side of anode body 121. First surface 123F1 and second surface 123F2 are substantially flat surfaces except for areas where convex portions 129 (described in detail below) are formed.

[0029] Conductive polymer layer 123 does not cover one end 121EL1 of anode body 121 in first direction DIR1. Conductive polymer layer 123 covers the other end 121EL2 of anode body 121 in first direction DIR1 via dielectric layer 122.

[0030] The conductive polymer layer 123 may be, for example, a conductive polymer having a skeleton of pyrroles, thiophenes, anilines, or the like, or a PEDOT:PSS layer realized by PEDOT [poly(3,4-ethylenedioxythiophene)], a conductive polymer having a skeleton of thiophenes, and composited with polystyrene sulfonic acid (PSS) as a dopant. The conductive polymer layer 123 is formed by a method of forming a polymer film of poly(3,4-ethylenedioxythiophene) or the like on the surface of the dielectric layer 122 using an electrolyte solution, for example, a treatment liquid containing a monomer such as 3,4-ethylenedioxythiophene, or a method of applying a dispersion of a polymer such as poly(3,4-ethylenedioxythiophene) to the surface of the dielectric portion and drying it.

[0031] The conductive layer 124 has a two-layer structure of a carbon layer 1241 and a silver layer 1242. The carbon layer 1241 is formed on the surface of the conductive polymer layer 123. The silver layer 1242 is formed on the surface of the carbon layer 1241.

[0032] The conductive layer 124 has a surface 124F1 on the first surface 123F1 side of the conductive polymer layer 123. The conductive layer 124 has a surface 124F2 on the second surface 123F2 side of the conductive polymer layer 123. The surfaces 124F1 and 124F2 are substantially flat surfaces except for portions of the conductive polymer layer 123 where convex portions 129 (described in detail below) are formed.

[0033] Conductive layer 124 has a first end 124EL1 on one end 121EL1 side of anode body 121 in first direction DIR1, and a second end 124EL2 on the other end 121EL2 side.

[0034] The conductive layer 124 has a first side end 124ES1 at one end in the second direction DIR2 and a second side end 124ES2 at the other end.

[0035] The conductive layer 124 has an edge 124CN1 where the second end 124EL2 and the first side end 124ES1 intersect, and has an edge 124CN2 where the second end 124EL2 and the second side end 124ES2 intersect.

[0036] The thickness of the conductive layer 124 is preferably, for example, 2 μm or more and 20 μm or less.

[0037] With this configuration, capacitor element 12 functions as a solid electrolytic capacitor with anode body 121 as the anode and conductive polymer layer 123 and conductive layer 124 as the cathode.

[0038] The capacitor element 12 may further include an insulating mask layer of a predetermined width provided on the periphery of the dielectric layer 122. In this case, the insulating mask layers are provided on both main surfaces and both side surfaces of the anode body 121 so as to be parallel to the short sides of the anode body 121. The insulating mask layers effectively separate the anode body 121 into an anode and a cathode. That is, the region where the conductive polymer layer 123 and the conductive layer 124 (the carbon layer 1241 and the silver layer 1242) are not formed is the anode, and the region where the conductive polymer layer 123 and the conductive layer 124 are formed is the cathode.

[0039] The conductive polymer layer 123 may be provided so as to cover at least a portion of the outer surface of the insulating mask layer, or may be provided so that the tip of the conductive polymer layer 123 on the insulating mask layer side does not overlap the insulating mask layer. The insulating mask layer may also be provided in the capacitor elements of the following embodiments.

[0040] Furthermore, capacitor element 12 includes protrusions 129. Protrusions 129 are formed on first surface 123F1 and second surface 123F2 of conductive polymer layer 123. Protrusions 129 are made of the same material as conductive polymer layer 123.

[0041] 4, the height H129 of the protrusion 129 is greater than the thickness D124 of the conductive layer 124. Note that the height H129 of the protrusion 129 may be equal to or less than the thickness D124 of the conductive layer 124, but is preferably greater.

[0042] The convex portions 129 on the first surface 123F1 protrude from the first surface 123F1 toward the conductive layer 124 that abuts against the first surface 123F1. The convex portions 129 on the second surface 123F2 protrude from the second surface 123F2 toward the conductive layer 124 that abuts against the second surface 123F2.

[0043] The convex portions 129 on the first surface 123F1 and the convex portions 129 on the second surface 123F2 have the same shape when the capacitor element 12 is viewed in plan, and overlap with each other.

[0044] More specifically, in a planar view of the capacitor element 12, the convex portion 129 is composed of a rod-shaped first convex portion 1291 extending along the second direction DIR2 and two rod-shaped second convex portions 1292 extending along the first direction DIR1.

[0045] The first convex portion 1291 is formed near the second end 124EL2 of the conductive layer 124 in the first direction DIR1 and has a shape extending parallel to the direction in which the second end 124EL2 extends. One end of the first convex portion 1291 in the extension direction is located near the first side end 124ES1, and the other end is located near the second side end 124ES2. In other words, the first convex portion 1291 is formed on the conductive polymer layer 123 in a shape that extends over substantially the entire length of the conductive layer 124 and the conductive polymer layer 123 in the second direction DIR2.

[0046] One of the second protrusions 1292 is formed near the first side end 124ES1 of the conductive layer 124 in the second direction DIR2 and has a shape that extends parallel to the direction in which the first side end 124ES1 extends. One end of the one of the second protrusions 1292 in the extension direction is connected to the end of the first protrusion 1291 on the first side end 124ES1 side. One of the second protrusions 1292 in the extension direction is shaped to extend from the end connected to the first side end 124ES1 toward the first end 124EL1 of the conductive layer 124. The other end of the one of the second protrusions 1292 in the extension direction is located closer to the second end 124EL2 than the center of the conductive layer 124 and the conductive polymer layer 123 in the first direction DIR1. In other words, the other end of one second convex portion 1292 in the extending direction is not positioned closer to first end 124EL1 than the center of conductive layer 124 and conductive polymer layer 123 in first direction DIR1.

[0047] The other second protrusion 1292 is formed near the second side end 124ES2 of the conductive layer 124 in the second direction DIR2 and has a shape that extends parallel to the extension direction of the second side end 124ES2. One end of the other second protrusion 1292 in the extension direction is connected to the end of the first protrusion 1291 on the second side end 124ES2 side. The other second protrusion 1292 has a shape that extends from the end connected to the second side end 124ES2 toward the first end 124EL1 of the conductive layer 124. The other end of the other second protrusion 1292 in the extension direction is located closer to the second end 124EL2 than the center of the conductive layer 124 and the conductive polymer layer 123 in the first direction DIR1. In other words, the other end of the other second convex portion 1292 in the extending direction is not located closer to first end 124EL1 than the center of conductive layer 124 and conductive polymer layer 123 in first direction DIR1.

[0048] As described above, the convex portion 129 has a shape in which a first convex portion 1291 extending along the second direction DIR2 and two second convex portions 1292 extending along the first direction DIR1 are connected. In other words, the convex portion 129 has a shape that is bent at approximately right angles at two locations in the direction in which it extends as a whole. By having these bent portions, the convex portion 129 has a shape that extends along the ridge portion 124CN1 (a first corner when the conductive layer 124 is viewed in a plan view) and the ridge portion 124CN2 (a second corner when the conductive layer 124 is viewed in a plan view).

[0049] A reference line Ls parallel to the second direction DIR2 is set midway between the first end 124EL1 and the second end 124EL2 with respect to the plane (surfaces 124F1, 124F2) of the conductive layer 124. This divides the plane (surfaces 124F1, 124F2) of the conductive layer 124 into a first region RE1 at the first end 124EL1 from the reference line Ls and a second region RE2 at the second end 124EL2 from the reference line Ls.

[0050] In this way, the convex portion 129 is formed in the second region RE2. Note that although a part of the second convex portion 1292 of the convex portion 129 may reach the first region RE1, it is preferable that substantially the entire convex portion 129 is formed in the second region RE2.

[0051] (Specific Configurations of the Laminated Capacitor 10 and the Solid Electrolytic Capacitor 1 ) As described above, the solid electrolytic capacitor 1 includes the laminated capacitor 10 , the first terminal electrode 20 , the second terminal electrode 30 , and the insulating resin body 40 .

[0052] 1, the plurality of capacitor elements 11-14 are stacked in the order of capacitor element 14, capacitor element 13, capacitor element 12, and capacitor element 11 from the bottom surface side to the top surface side of solid electrolytic capacitor 1. Capacitor element 11 and capacitor element 14 correspond to the "first capacitor elements," and capacitor element 12 and capacitor element 13 correspond to the "second capacitor elements."

[0053] The capacitor element in the bottom layer of capacitor laminate 10 is capacitor element 14, and the capacitor element in the top layer is capacitor element 11. Capacitor element 14 and capacitor element 13 are adjacent to each other in the stacking direction, capacitor element 13 and capacitor element 12 are adjacent to each other in the stacking direction, and capacitor element 12 and capacitor element 11 are adjacent to each other in the stacking direction.

[0054] Capacitor element 11 includes anode body 111, dielectric layer 112, conductive polymer layer 113, and conductive layer 114. Capacitor element 11 has substantially the same configuration as capacitor element 12 described above, but includes a protrusion 119 on only one surface in the thickness direction.

[0055] Capacitor element 12 has the above-described configuration and includes protrusions 129 on both sides in the thickness direction.

[0056] Capacitor element 13 includes an anode body 131, a dielectric layer 132, a conductive polymer layer 133, and a conductive layer 134. Capacitor element 13 has the same configuration as capacitor element 12 described above, and includes protrusions 139 on both sides in the thickness direction.

[0057] Capacitor element 14 includes an anode body 141, a dielectric layer 142, a conductive polymer layer 143, and a conductive layer 144. Capacitor element 14 has substantially the same configuration as capacitor element 12 described above, but includes a protrusion 149 on only one surface in the thickness direction.

[0058] The conductive layer 114 of capacitor element 11 and the conductive layer 124 of capacitor element 12 are in contact with each other. A portion of the plate-shaped second terminal electrode 30 is sandwiched between the conductive layer 124 of capacitor element 12 and the conductive layer 134 of capacitor element 13. The conductive layer 134 of capacitor element 13 and the conductive layer 144 of capacitor element 14 are in contact with each other.

[0059] Anode body 111 of capacitor element 11 , anode body 121 of capacitor element 12 , anode body 131 of capacitor element 13 , and anode body 141 of capacitor element 14 are bundled together and joined to a plate-shaped first terminal electrode 20 .

[0060] The laminated capacitor 10 having such a configuration, a portion of the first terminal electrode 20, and a portion of the second terminal electrode 30 are sealed with an insulating resin body 40. The insulating resin body 40 has a substantially rectangular parallelepiped shape having a top surface 401, a bottom surface 402, a first end surface 403, and a second end surface 404.

[0061] The first terminal electrode 20 is exposed to the outside from a first end surface 403 of the insulating resin body 40, and is bent along the first end surface 403 and the bottom surface 402. The second terminal electrode 30 is exposed to the outside from a second end surface 404 of the insulating resin body 40, and is bent along the second end surface 404 and the bottom surface 402.

[0062] The first terminal electrode 20 and the second terminal electrode 30 are preferably made of a metal material that is easy to bend and has high conductivity. The first terminal electrode 20 and the second terminal electrode 30 are made of, for example, a material cut out from a metal plate. The first terminal electrode 20 and the second terminal electrode 30 may be made of the same material or different materials.

[0063] The insulating resin body 40 is mainly made of resin and may contain a filler. Examples of preferred resins include epoxy resin, phenol resin, polyimide resin, silicone resin, polyamide resin, and liquid crystal polymer. The resin may be in either solid or liquid form. It is preferred that corners and edges are rounded by barrel polishing after resin sealing. Examples of preferred fillers include silica particles, alumina particles, and metal particles. The maximum diameter of the filler is preferably 30 μm or more and 40 μm or less. It is more preferred that the solid epoxy resin and phenol resin contain silica particles.

[0064] 5A and 5B are enlarged cross-sectional views showing the locations of protrusions when multiple capacitor elements are stacked. Fig. 5A shows the state before adjacent capacitor elements come into contact, and Fig. 5B shows the state after adjacent capacitor elements have come into contact. Fig. 5B shows the state of capacitor laminate 10 in solid electrolytic capacitor 1.

[0065] 5(A) and 5(B), by employing the above-described configuration, the convex portion 119 of the capacitor element 11 and the convex portion 129 of the capacitor element 12 face each other. The convex portion 129 of the capacitor element 12 and the convex portion 139 of the capacitor element 13 face each other. The convex portion 139 of the capacitor element 13 and the convex portion 149 of the capacitor element 14 face each other.

[0066] In this state, when forming the laminated capacitor 10, pressure is applied to the stacked capacitor elements 11-14 so as to sandwich them from above and below. In this case, the portions of the conductive layers 114, 124, 134, and 144 of the capacitor elements 11, 12, 13, and 14 where the protrusions 119, 129, 139, and 149 are formed come into contact with each other. Further pressure is then applied to the stacked capacitor elements 11-14, whereby the protrusions 119, 129, 139, and 149, each formed by a conductive polymer layer, are crushed, as shown in FIG. 5B .

[0067] This ensures a predetermined contact area between the adjacent conductive layers 114, 124, 134, and 144. Therefore, the laminated capacitor 10 can achieve stable electrical and physical connections between the adjacent conductive layers 114, 124, 134, and 144.

[0068] In this way, solid electrolytic capacitor 1 can connect adjacent capacitor elements among multiple capacitor elements 11-14 in a physically and electrically stable manner without using a separate conductive adhesive.

[0069] As a result, the solid electrolytic capacitor 1 can avoid the following various problems that arise from using a conductive adhesive, and can achieve the effects that are unique to the solid electrolytic capacitor 1.

[0070] For example, conductive adhesive is usually supplied in a paste form, but if too much is applied, the thickness of the capacitor laminate 10 becomes undesirably thick, which causes the capacitor laminate 10 to be exposed from the insulating resin body 40, resulting in a defective product.

[0071] However, since the solid electrolytic capacitor 1 does not use a conductive adhesive, it is possible to prevent the capacitor laminate 10 from becoming undesirably thick. This allows the solid electrolytic capacitor 1 to more reliably cover the capacitor laminate 10 with the insulating resin body 40.

[0072] In particular, in the above-described configuration, the uppermost capacitor element 11 and the lowermost capacitor element 14 do not have any convex portions that protrude outside the capacitor laminate 10. This allows the capacitor laminate 10 to be more reliably covered by the insulating resin body 40, thereby achieving a further reduction in thickness of the solid electrolytic capacitor 1.

[0073] Furthermore, if the amount of conductive adhesive is too large, it may overflow from the sides of the capacitor laminate 10. However, since the solid electrolytic capacitor 1 does not require the use of a conductive adhesive, such overflow does not occur.

[0074] Furthermore, when a conductive adhesive is used, the conductive adhesive may undesirably fall onto the manufacturing equipment, which may cause contamination problems. However, the solid electrolytic capacitor 1 does not require the use of a conductive adhesive, and therefore can avoid contamination problems.

[0075] Furthermore, if the amount of conductive adhesive is too small, the adhesive strength between adjacent capacitor elements will be reduced. This can lead to, for example, peeling from the corners and edges of the cathode side of the capacitor element, leading to an increase in ESR and a decrease in reliability. However, because solid electrolytic capacitor 1 does not require the use of conductive adhesive, peeling and an increase in ESR can be avoided.

[0076] In particular, in the above-described configuration, the convex portions are formed in a concentrated manner at the end on the cathode side. This further prevents peeling and an increase in ESR in the solid electrolytic capacitor 1. Furthermore, in the above-described configuration, the convex portions are formed near and along the corners and ridges on the cathode side. This further prevents peeling and an increase in ESR in the solid electrolytic capacitor 1.

[0077] Furthermore, conductive adhesives often have a relatively high resistivity, but the solid electrolytic capacitor 1 does not require the use of a conductive adhesive, and therefore can achieve a low ESR.

[0078] Furthermore, since the solid electrolytic capacitor 1 does not require the use of a conductive adhesive, the number of components can be reduced, making it easier to manufacture. Furthermore, the reduction in the number of components also contributes to lowering the cost of the solid electrolytic capacitor 1.

[0079] In the above-described configuration, the convex portions 129 and 139 can also be used for connection with the second terminal electrode 30. This makes it possible to further stabilize the electrical and physical connection between the plurality of capacitor elements 12, 13 and the second terminal electrode 30.

[0080] In the above-described configuration, capacitor elements 12 and 13 located midway in the stacking direction have protrusions 129 and 139 on both sides, but they can also have protrusions on one side. However, by providing protrusions on both sides, electrical and physical connection can be ensured with lower pressure. This reduces damage to the anode body of solid electrolytic capacitor 1 due to pressure.

[0081] In the above configuration, the convex portion includes a first convex portion extending along the second direction DIR2 and a second convex portion extending along the first direction DIR1. However, it is sufficient for the convex portion to include either the first convex portion or the second convex portion, and preferably includes at least the first convex portion.

[0082] Furthermore, in the above-described configuration, conductive layer 124 made up of carbon layer 1241 and silver layer 1242 covers convex portion 129. This improves the connection reliability between adjacent capacitor elements, enabling a further reduction in ESR to be achieved.

[0083] In the above-described configuration, the thickness of the capacitor element, i.e., the thickness of the structure including the anode body, dielectric layer, conductive polymer layer, and conductive layer, is constant except for the protruding portions. However, in this structure, the second region RE2 may be thicker than the first region RE1, excluding the protruding portions. Furthermore, in this structure, the thickness may be increased toward the cathode end. This allows the capacitor elements 11, 12, 13, and 14 to be tilted so that the ends of the capacitor elements 11, 12, 13, and 14 on the exposed anode body side are centered at the center of the capacitor stack 10 in the height direction (thickness direction). This, for example, reduces the amount of curvature (bending) of the anode bodies 111 and 141 in the capacitor elements 11 and 14. This therefore reduces damage to the anode bodies 111 and 141.

[0084] (Method of Manufacturing Capacitor Element) FIGS. 6A, 6B, 6C, 6D, and 6E are plan views showing the states of the capacitor element according to the first embodiment in each manufacturing process.

[0085] 6A, anode body 121 is cut to a predetermined size. Dielectric layer 122 has already been formed on anode body 121 by oxidizing the surface in an aqueous solution containing boric acid, phosphoric acid, adipic acid, or a sodium salt or ammonium salt thereof to form an oxide film on the surface.

[0086] Next, as shown in FIG. 6B, a strip-shaped mask MK for conductive polymer layer 123 and conductive layer 124 is formed by screen printing at a position a predetermined distance from one end 121EL1 of anode body 121.

[0087] Next, as shown in FIG. 6C, conductive polymer layer 123 is formed on the other end 121EL2 side of anode body 121 by DIP coating.

[0088] Next, as shown in FIG. 6D, convex portions 129 are formed on the conductive polymer layer 123 using a dispenser or the like.

[0089] 6(E), a carbon layer and a silver layer are successively formed by DIP coating so as to cover the conductive polymer layer 123 on which the protrusions 129 are formed, thereby forming a conductive layer 124.

[0090] [Second Embodiment] A solid electrolytic capacitor according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 7(A) is a plan view of the capacitor element according to the second embodiment, and Fig. 7(B) is a side cross-sectional view.

[0091] 7A and 7B, the capacitor laminate and solid electrolytic capacitor according to the second embodiment differ from the capacitor laminate and solid electrolytic capacitor according to the first embodiment in the configuration of the capacitor elements that make them up. Other configurations of the capacitor laminate and solid electrolytic capacitor according to the second embodiment are similar to those of the capacitor laminate and solid electrolytic capacitor according to the first embodiment, and a description of similar parts will be omitted.

[0092] The capacitor laminate and the multiple capacitor elements constituting the solid electrolytic capacitor according to the second embodiment have the same configuration, and the following description will be given using capacitor element 12A in comparison with capacitor element 12 according to the first embodiment.

[0093] Capacitor element 12A according to the second embodiment differs from capacitor element 12 according to the first embodiment in that convex portion 129 is exposed from conductive layer 124. Other configurations of capacitor element 12A are similar to those of capacitor element 12, and descriptions of similar parts will be omitted.

[0094] The conductive layer 124 has an opening OP124A through which the protrusion 129 passes. The protrusion 129 passes through the opening OP124A and protrudes outward beyond the surfaces 124F1 and 124F2 of the conductive layer 124.

[0095] With this configuration, the laminated capacitor and solid electrolytic capacitor according to the second embodiment achieve the same effects as the laminated capacitor 10 and solid electrolytic capacitor 1 according to the first embodiment.

[0096] Furthermore, in this configuration, the conductive polymer layers of adjacent capacitor elements can be directly connected to each other, resulting in the lowest resistance at the connection points.

[0097] This configuration can be achieved by applying a liquid repellent agent to the surfaces of the convex portions 129 when the carbon layer 1241 and the silver layer 1242 are formed, for example.

[0098] [Third Embodiment] A solid electrolytic capacitor according to a third embodiment of the present invention will be described with reference to the drawings. Fig. 8(A) is a plan view of a capacitor element according to the third embodiment, and Fig. 8(B) is a side cross-sectional view.

[0099] 8A and 8B, the capacitor laminate and solid electrolytic capacitor according to the third embodiment differ from the capacitor laminate and solid electrolytic capacitor according to the first embodiment in the configuration of the capacitor elements that make them up. Other configurations of the capacitor laminate and solid electrolytic capacitor according to the third embodiment are similar to those of the capacitor laminate and solid electrolytic capacitor according to the first embodiment, and a description of similar parts will be omitted.

[0100] The capacitor laminate and the multiple capacitor elements constituting the solid electrolytic capacitor according to the second embodiment have the same configuration, and the following description will be given using capacitor element 12B in comparison with capacitor element 12 according to the first embodiment.

[0101] Capacitor element 12B according to the third embodiment differs from capacitor element 12 according to the first embodiment in that convex portion 129 is covered only with carbon layer 1241 and not with silver layer 1242. The other configuration of capacitor element 12B is the same as that of capacitor element 12, and a description of similar parts will be omitted.

[0102] The silver layer 1242 of the conductive layer 124 has an opening OP124B through which the protrusion 129 covered with the carbon layer 1241 passes. The protrusion 129 covered with the carbon layer 1241 passes through the opening OP124B and protrudes outward beyond the surfaces 124F1 and 124F2 of the conductive layer 124.

[0103] With this configuration, the laminated capacitor and solid electrolytic capacitor according to the third embodiment achieve the same effects as the laminated capacitor 10 and solid electrolytic capacitor 1 according to the first embodiment.

[0104] Furthermore, in this configuration, the carbon layers of adjacent capacitor elements are directly connected to each other, which provides an anchor effect and improves connection reliability.

[0105] This configuration can be realized, for example, by applying a liquid repellent agent to the surface of the convex portion 129 covered with the carbon layer 1241 when the silver layer 1242 is formed.

[0106] [Fourth Embodiment] A solid electrolytic capacitor according to a fourth embodiment of the present invention will be described with reference to the drawings. Fig. 9 is a side cross-sectional view of the solid electrolytic capacitor according to the fourth embodiment.

[0107] 9 , the solid electrolytic capacitor 1C according to the fourth embodiment differs from the solid electrolytic capacitor 1 according to the first embodiment in a capacitor laminate 10C, a first terminal electrode 20C, and a second terminal electrode 30C. Only the differences from the solid electrolytic capacitor 1 will be described below.

[0108] The laminated capacitor 10C includes a plurality of capacitor elements 11, 12, 13, and 14C. Like the capacitor elements 12 and 13, the capacitor element 14C includes protrusions on both sides.

[0109] The anode bodies of the plurality of capacitor elements 11, 12, 13, and 14C are bundled together, and this bundled portion is connected to a first terminal electrode 20C.

[0110] The second terminal electrode 30C has a flat base 309. The capacitor laminate 10C is placed on the base 309. At this time, the protrusions of the capacitor element 14C are crushed. This improves the connection reliability between the capacitor element 14C and the base 309.

[0111] The configurations shown in the above-described embodiments can be combined as appropriate, and effects according to each combination can be achieved.

[0112] <1> A capacitor laminate including a plurality of capacitor elements, each of which has a flat film shape and is stacked so that each flat film surface overlaps, wherein the capacitor elements include: an anode body formed of a film-like valve metal; a dielectric layer covering the anode body; a conductive polymer layer covering the dielectric layer; and a conductive layer covering the conductive polymer layer, the conductive layer being formed with a predetermined area that does not include one end of the anode body in a first direction but includes the other end, the conductive layer having a first end on the one end side and a second end on the other end side, wherein the conductive layer and the conductive polymer layer have a first region on the first end side and a second region on the second end side in a plane on which the conductive layer is formed, the conductive polymer layer having a first protrusion that extends in the second region in a direction perpendicular to the first direction and protrudes toward the conductive layer, the first protrusions of adjacent capacitor elements in the plurality of capacitor elements at least partially overlap in the stacking direction, and adjacent capacitor elements in the plurality of capacitor elements are connected via their respective first protrusions.

[0113] <2> The capacitor laminate according to <1>, wherein the height of the first protrusion is greater than the thickness of the conductive layer.

[0114] <3> The capacitor laminate according to <1> or <2>, further comprising a second protrusion extending in a direction parallel to the first direction in the anode body and protruding toward the conductive layer.

[0115] <4> The capacitor laminate of <3>, wherein the second convex portion is composed of a third convex portion and a fourth convex portion running side by side, the third convex portion is formed adjacent to and parallel to a first side end of the anode body that is parallel to the first direction, and the fourth convex portion is formed adjacent to and parallel to a second side end of the anode body that is parallel to the first direction and opposite the first side end.

[0116] <5> The capacitor laminate of <4>, wherein the first convex portion and the third convex portion are formed along a first corner where the first end and the first side end intersect, and the first convex portion and the fourth convex portion are formed along a second corner where the first end and the second side end intersect.

[0117] <6> The capacitor laminate according to <1> or <2>, wherein the conductive layer covers the first protrusion.

[0118] <7> The capacitor laminate according to any one of <1> to <6>, wherein the plurality of capacitor elements include first capacitor elements located at both ends in the stacking direction and second capacitor elements arranged between the first capacitor elements, the first capacitor elements include the first convex portion only on a surface where an adjacent capacitor element is present, and the second capacitor elements include the first convex portion on both surfaces.

[0119] <8> The capacitor laminate according to any one of <1> to <7>, wherein the conductive layer includes a carbon layer formed on the outer surface of the conductive polymer layer, and a silver layer formed on the outer surface of the carbon layer.

[0120] <9> The capacitor laminate according to any one of <1> to <8>, wherein a portion of the capacitor element corresponding to the second region is thicker than a portion of the capacitor element corresponding to the first region.

[0121] <10> A solid electrolytic capacitor comprising: a capacitor laminate according to any one of <1> to <9>; an insulating resin body covering the capacitor laminate; a first terminal electrode having a portion exposed on an outer surface of the insulating resin body and connected to the anode bodies of the plurality of capacitor elements; and a second terminal electrode having a portion exposed on the outer surface of the insulating resin body and connected to the conductive layers of the plurality of capacitor elements.

[0122] 1, 1C: solid electrolytic capacitor 10, 10C: capacitor laminate 11, 12, 12A, 12B, 13, 14, 14C: capacitor element 20, 20C: first terminal electrode 30, 30C: second terminal electrode 40: insulating resin body 111, 121, 131, 141: anode body 112, 122, 132, 142: dielectric layer 113, 123, 133, 143: conductive polymer layer 114, 124, 134, 144: conductive layer 119, 129, 139, 149: convex portion 1241: carbon layer 1242: silver layer 1291: first convex portion 1292: second convex portion 124CN1, 124CN2: ridge portion OP124A, OP124B: opening

Claims

1. A capacitor laminate comprising a plurality of capacitor elements, each of which has a flat film shape and is stacked so that their flat film surfaces overlap, wherein the capacitor elements comprise: an anode body formed of a film-shaped valve action metal; a dielectric layer covering the anode body; a conductive polymer layer covering the dielectric layer; and a conductive layer covering the conductive polymer layer, formed with a predetermined area that does not include one end of the anode body in a first direction but includes the other end, and having a first end on the one end side and a second end on the other end side, wherein the conductive layer and the conductive polymer layer have a first region on the first end side and a second region on the second end side in a plane on which the conductive layer is formed, and the conductive polymer layer has a first convex portion that extends in a direction perpendicular to the first direction in the second region and protrudes toward the conductive layer, the first convex portions of adjacent capacitor elements in the plurality of capacitor elements at least partially overlap when viewed in the stacking direction, and adjacent capacitor elements in the plurality of capacitor elements are connected via their respective first convex portions.

2. The capacitor laminate according to claim 1, wherein the height of said first protrusion is greater than the thickness of said conductive layer.

3. The capacitor laminate according to claim 1 or 2, further comprising a second protrusion extending in a direction parallel to the first direction in the anode body and protruding towards the conductive layer.

4. The capacitor laminate described in claim 3, wherein the second convex portion is composed of a third convex portion and a fourth convex portion running side by side, the third convex portion is formed adjacent to and parallel to a first side end of the anode body parallel to the first direction, and the fourth convex portion is formed adjacent to and parallel to a second side end of the anode body parallel to the first direction and opposite the first side end.

5. The capacitor laminate as described in claim 4, wherein the first convex portion and the third convex portion are formed along a first corner where the first end and the first side end intersect, and the first convex portion and the fourth convex portion are formed along a second corner where the first end and the second side end intersect.

6. The capacitor laminate according to claim 1 or 2, wherein the conductive layer covers the first protrusion.

7. A capacitor laminate as described in any one of claims 1 to 6, wherein the plurality of capacitor elements comprise first capacitor elements located at both ends in the stacking direction and second capacitor elements arranged between the first capacitor elements, the first capacitor elements comprise the first convex portion only on a surface on which an adjacent capacitor element is present, and the second capacitor elements comprise the first convex portion on both surfaces.

8. The capacitor laminate according to any one of claims 1 to 7, wherein the conductive layer comprises a carbon layer formed on the outer surface of the conductive polymer layer, and a silver layer formed on the outer surface of the carbon layer.

9. The capacitor laminate according to claim 1, wherein a portion of the capacitor element corresponding to the second region is thicker than a portion of the capacitor element corresponding to the first region.

10. A solid electrolytic capacitor comprising: a capacitor laminate according to any one of claims 1 to 9; an insulating resin body covering the capacitor laminate; a first terminal electrode having a portion exposed on an outer surface of the insulating resin body and connected to the anode bodies of the plurality of capacitor elements; and a second terminal electrode having a portion exposed on the outer surface of the insulating resin body and connected to the conductive layers of the plurality of capacitor elements.

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