Solid electrolytic capacitor and method for manufacturing same

Abstract

[Problem] To provide a solid electrolytic capacitor suitable for high capacity, and a method for manufacturing the same. [Solution] A solid electrolytic capacitor 10 comprising: an insulating molded body 12 having therein a laminate 11 in which a capacitor element 20 having a solid electrolyte is laminated; a first external electrode 51 provided on a first end surface 12a of the insulating molded body 12; and a second external electrode 52 provided on a second end surface 12b of the insulating molded body 12. The insulating molded body 12 includes: a filler 14 covering at least one first main surface 11a along the lamination direction of the laminate; and a molding die 16 having at least a bottom plate part 16a arranged at a position directly or indirectly covering a second main surface 11b on the opposite side from the first main surface in the lamination direction of the laminate 11.

Description

Solid electrolytic capacitor and method of manufacturing the same

[0001] The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same.

[0002] For example, as shown in Patent Document 1 below, attempts have been made to increase the capacitance of solid electrolytic capacitors by increasing the number of capacitor elements contained therein.

[0003] However, the conventional solid electrolytic capacitor structures involve stacking capacitor elements on a printed circuit board or the like, which makes it difficult to stack a large number of elements and places a limit on the number of elements that can be stacked, hindering efforts to increase capacitance.

[0004] Japanese Patent Application Laid-Open No. 2008-078230

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid electrolytic capacitor suitable for achieving high capacitance, and a method for manufacturing the same.

[0006] In order to achieve the above-mentioned object, one embodiment of the solid electrolytic capacitor of the present invention is a solid electrolytic capacitor having an insulating molding having an internal laminate in which one or more capacitor elements having a solid electrolyte are stacked, a first external electrode provided on a first end face of the insulating molding, and a second external electrode provided on a second end face of the insulating molding, wherein the insulating molding has a filler covering at least one first main surface along the stacking direction of the laminate, and a molding die having at least a bottom plate portion positioned in a position so as to directly or indirectly cover a second main surface opposite the first main surface along the stacking direction of the laminate.

[0007] In this solid electrolytic capacitor, the laminate is placed inside a molding die, and then the filler that will form the filler is poured into the molded body, and the laminate is covered with an insulating molded body, eliminating limitations on the number of stacked elements in the laminate.This makes it easy to realize high-capacity solid electrolytic capacitors.

[0008] Preferably, the mold has side walls or side corners that are continuous with the bottom plate and are positioned so as to directly or indirectly cover at least a portion of the side peripheral surface of the laminate. In such a configuration, the side walls or side corners serve as positioning and guides when placing the laminate inside the mold, making it possible to place the laminate inside the mold in an orderly manner along the stacking direction.

[0009] In other words, it becomes easier to arrange the stacked elements in an orderly manner, generally parallel to the bottom plate, without tilting some of the elements inside the mold, which contributes to increasing the number of stacked elements. Furthermore, by leaving the sidewalls of the mold on the solid electrolytic capacitor, the moisture resistance and reliability of the product are improved.

[0010] Preferably, at a first end surface of the insulating molding, a first end portion of a first element electrode of each of the capacitor elements is exposed and connected to the first external electrode, and at a second end surface of the insulating molding, a paste electrode that is connected to integrate the second ends of the second element electrodes of each of the capacitor elements is exposed and connected to the second external electrode.

[0011] This configuration shortens the length of the lead-out region from the element electrode to the external electrode of the element, thereby reducing the ESR and enabling the device to be more compact. In addition, the paste electrode can reliably connect the stacked second element electrodes to the second external electrode, improving connection reliability.

[0012] Preferably, a pair of side corners that are continuous with the bottom plate of the mold are located on both sides of the paste electrode. By configuring in this manner, it becomes easier to pour conductive paste into the gap between the side corners during manufacturing, and it becomes possible to easily manufacture a structure in which stacked second element electrodes are connected by paste electrodes along the stacking direction.

[0013] Preferably, the step distance of the side corner from the second end face is 2 to 400 μm. This configuration facilitates the formation of paste electrodes with a predetermined thickness of 2 to 400 μm. By making the paste electrode thickness equal to or greater than the predetermined value, dimensional variations between the capacitor elements and their second element electrodes can be absorbed, enabling reliable connection between the second element electrodes and second external electrodes of all capacitor elements, contributing to improved reliability. Furthermore, making the paste electrode thickness equal to or less than the predetermined value contributes to reduced ESR and cost.

[0014] The width between the pair of side corners may be smaller than the width of the second element electrode of the capacitor element, and a second end of the second element electrode may be connected to the paste electrode located between the pair of side corners. Alternatively, the width between the pair of side corners may be larger than the width of the second element electrode of the capacitor element, and the second end of the second element electrode may be inserted between the pair of side corners and connected to the paste electrode.

[0015] Preferably, the second ends of the second element electrodes of the capacitor elements adjacent in the stacking direction in the laminate are fixed together with a conductive or non-conductive adhesive. The plurality of capacitor elements may be stacked with an adhesive to form a laminate, and then the laminate may be placed inside a molding die. Alternatively, the plurality of capacitor elements may be bonded with an adhesive while being placed inside a molding die, either individually or in blocks, and then the laminate may be assembled and placed inside a molded body.

[0016] Preferably, the adhesive is disposed between the second ends of the second element electrodes of the capacitor elements adjacent in the stacking direction in the laminate so as to prevent the paste electrodes from entering between the second ends of the second element electrodes of the capacitor elements adjacent in the stacking direction in the laminate. This configuration makes it possible to reduce the amount of rare metal (e.g., Ag) used in the paste electrodes, thereby contributing to cost reduction.

[0017] The first element electrode may be made of, for example, a valve metal, and may have an etched or sintered metal. For example, but not limited to, the first element electrode may be an anode and the second element electrode may be a cathode.

[0018] A method for manufacturing a solid electrolytic capacitor according to one aspect of the present invention includes the steps of: placing a laminate, in which capacitor elements each having a solid electrolyte are stacked, in a cavity of an insulating mold having a bottom plate portion and a sidewall portion integral with the bottom plate portion; pouring a conductive paste into the cavity of the mold in which the laminate is placed and hardening the paste to form a paste electrode that integrates second ends of second element electrodes of the capacitor elements in the laminate; injecting an insulating material into the cavity of the mold through an opening in the sidewall portion to form a filler inside the mold that covers at least one first main surface along the stacking direction of the laminate; cutting an insulating molded body consisting of the mold and the filler to form a first cut surface so that first ends of first element electrodes of the capacitor elements in the laminate located inside the mold are exposed to the outside; and cutting the insulating molded body to form a second cut surface so that ends of the paste electrodes located inside the mold are exposed to the outside. The method includes the steps of: forming a first external electrode on a first cut surface of the insulating molding; and connecting ends of the stacked first element electrodes to the first external electrode; and forming a second external electrode on a second cut surface of the insulating molding; and connecting the paste electrode to the second external electrode.

[0019] Preferably, a recess is provided in a part of the inner wall surface of the side wall of the molding die, and the conductive paste is poured into the recess. The formation of the recess makes it easy to position and arrange the laminate inside the molding die, and also makes it easy to pour the conductive paste along the recess.

[0020] Preferably, the depth of the recess is 2 to 400 μm. By configuring in this way, it becomes easier to form a paste electrode made of conductive paste with a predetermined thickness corresponding to the depth of the recess.

[0021] The inner wall surface of the side wall on which the recess is formed may be tapered so that the depth of the recess becomes shallower toward the bottom plate portion. By configuring in this manner, it is easier to pour the conductive paste along the recess.

[0022] Preferably, the mold is pre-molded from a molding resin.

[0023] Preferably, the mold comprises a first mold having a first cavity corresponding to the cavity, and a second mold molded continuously from the first mold and having a second cavity corresponding to the cavity, wherein a first recess facing the first cavity is formed on one side wall surface of an intermediate side wall portion separating the first cavity and the second cavity, and a second recess facing the second cavity is formed on the other side wall surface of the intermediate side wall portion, and the first recess and the second recess have a configuration corresponding to the recesses.

[0024] With this configuration, a large number of solid electrolytic capacitors can be easily manufactured at the same time.

[0025] The mold may include a first mold having a first cavity corresponding to the cavity, and a second mold formed continuously from the first mold and having a second cavity corresponding to the cavity, and a notch may be formed in an intermediate side wall portion separating the first cavity and the second cavity, allowing the conductive paste to be poured continuously between the first cavity and the second cavity.

[0026] With this configuration, it becomes possible to supply the conductive paste to two cavities simultaneously by a single application (pouring) operation of the conductive paste.

[0027] FIG. 1A is a schematic perspective view of a solid electrolytic capacitor according to a first embodiment. FIG. 1B is a schematic perspective view of a solid electrolytic capacitor according to another embodiment. FIG. 2A is a schematic cross-sectional view taken along line IIA-IIA in FIG. 1A. FIG. 2B is a schematic cross-sectional view showing an enlarged view of the capacitor element and its surrounding structure shown in FIG. 2A. FIG. 3A is a schematic cross-sectional view taken along line IIIA-IIIA in FIG. 2A. FIG. 3B is a schematic cross-sectional view showing a modified example of the solid electrolytic capacitor shown in FIG. 3A. FIG. 4 is a schematic perspective view of a mold used to manufacture the solid electrolytic capacitor shown in FIG. 1A. FIG. 5A is a conceptual diagram of a planar pattern showing the shape of a portion of the mold shown in FIG. 4 in the XY plane. FIG. 5B is a conceptual diagram of a planar pattern of a mold showing a modified example of the shape of the mold shown in FIG. 5A. FIG. 5C is a conceptual diagram of a planar pattern of a mold showing a further modified example of the shape of the mold shown in FIG. 5A. FIG. 5D is a conceptual diagram of a planar pattern of a mold showing a further modified example of the shape of the mold shown in FIG. 5A. FIG. 5E is a conceptual diagram of a planar pattern of a mold showing a further modified example of the shape of the mold shown in FIG. 5A. FIG. 6A is a schematic cross-sectional view of a molding die taken along line VIA-VIA shown in FIG. 5A. FIG. 6B is a schematic cross-sectional view of a molding die according to a modification of the molding die shown in FIG. 6B. FIG. 6C is a schematic cross-sectional view of a molding die according to a further modification of the molding die shown in FIG. 6B. FIG. 7A is a schematic exploded perspective view showing a method for producing a laminate for the solid electrolytic capacitor shown in FIG. 2A. FIG. 7B is a schematic perspective view of a laminate showing a step subsequent to the step shown in FIG. 7A. FIG. 7C is a schematic perspective view showing a step of applying adhesive to the interior of a molding die that accommodates the laminate shown in FIG. 7B. FIG. 7D is a schematic perspective view showing a step of placing the laminate shown in FIG. 7B inside a molding die. FIG. 7E is a schematic perspective view showing a step subsequent to that shown in FIG. 7D. FIG. 7F is a schematic perspective view showing a step subsequent to that shown in FIG. 7E. FIG. 7G is a schematic perspective view showing a step subsequent to that shown in FIG. 7E. FIG. 8A is a schematic plan view showing a step subsequent to that shown in FIG. 7F, illustrating the cutting position. FIG. 8B is a schematic plan view showing the cutting position according to the modification of FIG. 8B. Fig. 8C1, Fig. 8C2, and Fig. 8D are schematic plan views showing cutting positions according to the modified example of Fig. 8A.FIG. 9 is a schematic cross-sectional view of the insulating molding after being cut in the step shown in FIG. 8A.

[0028] The following describes the embodiments.

[0029] 1A, a solid electrolytic capacitor 10 according to this embodiment has an insulating compact 12. As shown in Fig. 2A, a first external electrode 51 is provided on a first end surface 12a of the insulating compact 12 along the X-axis, and a second external electrode 52 is provided on a second end surface 12b.

[0030] A laminate 11 is disposed inside the insulating molding 12, in which a large number of capacitor elements 20 are stacked along the Z axis with adhesive layers 60 interposed therebetween. In this embodiment, the thickness T (see FIG. 2A) of each capacitor element 20 along the Z axis is not particularly limited, but is, for example, about 20 to 500 μm. In the drawings, the X axis, Y axis, and Z axis are perpendicular to one another.

[0031] 2B , each capacitor element 20 has a first element electrode 21, a second element electrode 22, and a solid electrolyte layer 24 and a dielectric layer 28 disposed between these electrodes 21 and 22. In this embodiment, the first element electrode 21 is made of a thin plate of valve metal and constitutes the anode of the capacitor 10.

[0032] In this embodiment, the first element electrode 21 is made of aluminum metal foil with an etched surface, but other than aluminum, tantalum, niobium, or the like may also be used as the valve metal constituting the electrode 21. Furthermore, the shape of the first element electrode 21 is not limited to a foil shape (including a plate shape), and at least a portion of it may be rod-shaped or block-shaped.

[0033] The surface of the main portion of the first element electrode 21, excluding the first lead-out end 21a of the first element electrode 21, is preferably roughened (enlarged) by etching or the like to increase the surface area and made porous. The surface of the main portion of the first element electrode 21 is also preferably provided with a dielectric layer 28 by chemical conversion treatment (anodization) or the like. The dielectric layer 28 is formed, for example, from an aluminum oxide coating.

[0034] The surface of the main part of the first element electrode 21 is not limited to being etched to increase the surface area, but may be made of a sintered metal surface, etc. By configuring it in this way, the surface area of ​​the electrode is increased, and the capacitance can be increased.

[0035] The solid electrolyte layer 24 present around the dielectric layer 28 contains a conductive polymer compound. The conductive polymer compound contained in the solid electrolyte layer 24 is not particularly limited, but examples thereof include polythiophene and polypyrrole. Although shown in a simplified form in Figures 2A and 2B, the inner surface of the solid electrolyte layer 24 has a complex shape that penetrates into the roughened surface of the first element electrode 21. The thickness of the solid electrolyte layer 24 is not particularly limited, but is, for example, about 5 to 30 µm.

[0036] The second element electrode 22 has a cylindrical shape with a bottom that covers the entire main portion of the first element electrode 21 via the dielectric layer 28 and the solid electrolyte layer 24, and in this embodiment, constitutes the cathode of the capacitor 10. The second element electrode 22 can be formed, for example, by a dipping method in which the main portion of the first element electrode 21, on which the dielectric layer 28 and the solid electrolyte layer 24 are formed, is immersed in a paste liquid for forming the second element electrode 22.

[0037] The second element electrode 22 has a current collecting function and may be configured as a single layer or multiple layers as long as it is a layer that contacts the outside of the solid electrolyte layer 24. In this embodiment, the second element electrode 21 has, for example, a graphite paste layer that contacts the outside of the solid electrolyte layer 24 and a silver paste layer that contacts the graphite paste layer from the outside, and performs a current collecting function. The thickness of the graphite paste layer can be, for example, about 1 to 10 μm, and the thickness of the silver paste layer can be, for example, about 5 to 30 μm.

[0038] Of the surfaces of the first element electrode 21, the first end 21a located on the first end face 12a side of the insulating molding 12 is preferably free of the dielectric layer 28 and the solid electrolyte layer 24. The outer peripheral surface of the first end 21a protruding outward along the X-axis beyond the first end 22a of the second element electrode 22 may be covered with a resist film 26, except for the end face 21a1 connected to the first external electrode 51. The resist film 26 is formed of an insulating resin such as epoxy resin or silicone resin, and preferably insulates the first element electrode 21 and the second element electrode 22 to prevent short-circuiting, but is not necessary as long as insulation is ensured.

[0039] In Figures 2A and 2B, the boundary between the dielectric layer 28 and the first element electrode 21 and the boundary between the dielectric layer 28 and the solid electrolyte layer 24 are depicted as straight lines for simplification, but in reality they have complex shapes that follow the roughened surface.

[0040] An end face 21a1 of the first end 21a along the X-axis of the first element electrode 21 is connected to the inside of the first external electrode 51 directly or via an end face deposition film 21a2. An end face of the second end 21b along the X-axis of the first element electrode 21 is covered by the second end 22b of the second element electrode 22 via the dielectric layer 28 and the solid electrolyte layer 24.

[0041] The second end 22b of the second element electrode 22 that is not covered by the adhesive layer 60 is electrically connected to the paste electrode 40, and the outer surface of the paste electrode 40 along the X-axis is connected to the second external electrode 52. The paste electrode 40 is made of a hardened conductive paste, such as a silver paste electrode made by hardening a silver paste containing silver powder and a binder resin (such as an epoxy resin), but may also be a paste electrode made of another conductive metal.

[0042] It is sufficient that at least the end surface of the second end 22b of the second element electrode 22 along the X-axis is connected to the paste electrode 40, but the main surface of the second end 22b (the surface substantially perpendicular to the Z-axis) that is not covered by the adhesive layer 60 may be connected to the paste electrode 40. Note that it is preferable that the adhesive layer 60 covers the main surface of the second end 22b as close to the end surface as possible, other than the end surface along the X-axis of the second end 22b of the second element electrode 22. This is to reduce the amount of paste electrode 40 used, which contains relatively expensive Ag.

[0043] The adhesive layer 60 is made of, for example, epoxy resin, acrylic resin, or the like. In this embodiment, the adhesive layer 60 is made of a non-conductive adhesive, which does not form a conductive path, but tends to have higher bonding strength than conductive adhesives, etc. Note that if the mechanical strength of the laminate 11 is ensured in relation to the number of layers of the capacitor elements 20, etc., the adhesive layer 60 can be omitted. The adhesive layer 60 may also be made of a conductive paste, such as silver paste, or may be something like an adhesive sheet.

[0044] 2A, the paste electrode 40 extends along the Z-axis so as to connect along the Z-axis the second ends 22b of the second element electrodes 22 of all of the capacitor elements 20 present inside the insulating molding 12. Also, as shown in Fig. 3A, the paste electrode 40 is preferably connected to the second element electrode 22 over the entire width, or over 30% or more, 40% or more, 50% or more, 60% or more, or 70% or more of the width of the second end 22b of the second element electrode 22 along the Y-axis.

[0045] 2A , in this embodiment, the insulating molding 12 includes a filler 14 and a molding die 16. The filler 14 covers at least one first main surface 11a (top surface substantially perpendicular to the Z axis) along the Z axis, which is the stacking direction of the laminate 11. The molding die 16 includes at least a bottom plate portion 16a disposed in a position that directly or indirectly covers a second main surface 11b opposite the first main surface 11a along the Z axis.

[0046] 3A, the molding die 16 has a pair of sidewalls 16b located on opposite outer surfaces of the insulating molding 12 along the Y axis. The lower portion of each sidewall 16b along the Z axis (the bottom plate portion 16a side) is continuous with the bottom plate portion 16a, and the sidewalls 16b and the bottom plate portion 16a are integrally formed.

[0047] As shown in FIG. 1A , the upper end surface 16b1 of the side wall portion 16b may be substantially flush with the upper surface 14b1 of the filler 14. Alternatively, as shown in FIG. 7G , the upper end surface 16b1 of the side wall portion 16b may also be covered by the upper surface 14b1 of the filler 14. For example, the upper end surface 16b1 of the side wall portion 16b may be covered at the same time as filling the cavity 162 with the filler 14. Alternatively, after filling the cavity 162 with the filler 14, the upper end surface 16b1 of the side wall portion 16b may be covered with the upper surface 14b1 of the filler 14 in a separate process. As shown in FIG. 2A , the bottom surface 14a of the filler 14 may be in contact with and integrated with the upper surface of the bottom plate portion 16a of the molding die 16.

[0048] 3A, one first end face 16b2 of the side wall portion 16b along the X axis is substantially flush with one first end face 14b2 along the X axis of the filler 14 filling the inside of the side wall portion 16b, and both are covered with and connected to a first external electrode 51. The first external electrode 51 is connected to an end face 21a1 of the first element electrode 21 of each capacitor element 20 and / or an end face deposited film 21a2 shown in FIG. 2B, and they are electrically connected to each other.

[0049] The end face 21a1 of the first element electrode 21 is formed on the same cut surface (or polished surface, etc.) as the tip face 26a of the resist film 26, the first end face 16b2 of the molding die 16, and the first end face 14b2 of the filler 14, and is formed to be approximately flush with them. Note that an end face deposition film 21a2 protruding from the end face 21a1 of the first element electrode 21 may be formed by, for example, plating, to further strengthen the mechanical and electrical connection between the first external electrode 51 and the first element electrode 21.

[0050] 3A , the other second end surface 16b3 of each of the pair of side wall portions 16b along the X-axis is formed with side corners 16c and protrusions 16d that protrude from the side corners 16c in directions toward each other along the Y-axis. A paste electrode 40 is inserted between the pair of protrusions 16d, and the paste electrode 40 electrically connects the second ends 22b of the plurality of second element electrodes 22 to the second external electrode 52. In other words, the pair of side corners 16c and protrusions 16d that are continuous with the bottom plate portion 16a of the molding die 16 are located on both sides along the Y-axis of the paste electrode 40 that electrically connects the plurality of second element electrodes 22 to the second external electrode 52.

[0051] In this embodiment, the width y1 along the Y-axis between the pair of protrusions 16d is narrower than the width y2 of the second end 22b of the capacitor element 20 along the Y-axis, and during the manufacturing process, the second end 22b abuts against the inner surface of the protrusion 16d, enabling the element 20 to be positioned along the X-axis inside the mold 16.

[0052] The width y1 along the Y axis between the pair of protrusions 16d may be smaller than the width y2 of the second end 22b of the capacitor element 20 along the Y axis, allowing the second end 22b of the element 20 to fit between the pair of protrusions 16d. The width y1 along the Y axis between the pair of protrusions 16d is not particularly limited, but is preferably y1 / y2 = 1 / 3 or more, 1 / 2 or more, or 2 / 3 or more of the width y2 of the second end 22b. Setting this width facilitates ensuring good electrical connection between the second external electrode 52 and the second element electrode 22. The upper limit of y1 / y2 is not particularly limited, but is preferably approximately 1.5 or less, or 1.2 or less. A too large y1 / y2 ratio would violate the demand for a compact capacitor 10. While the present embodiment includes a recess 16e, the recess 16e is not necessarily required, as shown in FIG. 8C1 , for example. In that case, y1 shown in FIG.

[0053] In this embodiment, the paste electrode 40 protrudes from the gap between the end 22 b of the element 20 and the protrusion 16 d toward the side corner 16 c, but may be contained within the gap between the pair of protrusions 16 d. The gap between the element 20 and the molding die 16 is filled with an insulating filler 14, except for the portion in contact with the first external electrode 51 and the portion in contact with the paste electrode 40.

[0054] As described above, the second ends 22b of the second element electrodes 22 of each stacked capacitor element 20 are continuously connected along the Z-axis by the paste electrode 40. The outer end surface 40a of the paste electrode 40, located outward along the X-axis, and the second end surface 12b of the insulating molding body 12 are substantially flush with each other. A second external electrode 52 is formed to cover these end surfaces 40a and 12b and is electrically connected to the paste electrode 40. The second end surface 12b includes the second end surface 14b3 of the filler 14 and the second end surface 16b3 of the molding die 16. The first end surface 12a includes the first end surface 14b2 of the filler 14 and the first end surface 16b2 of the molding die 16.

[0055] In this embodiment, the thickness of the paste electrode 40 along the X axis is preferably equal to or greater than the thickness X1 of the pair of protrusions 16d along the X axis, but may be thinner than the thickness X1 if the second end 22b of the element 20 fits between the pair of protrusions 16d. However, even in this case, the thickness of the paste electrode 40 along the X axis is preferably 2 μm or more, more preferably 5 μm or more, and is preferably 400 μm or less, more preferably 100 μm or less.

[0056] In this embodiment, the molding die 16 is made of an insulating material, and since it is assumed that it will be cut together with the filler 14 as will be described later in the manufacturing method, it is preferably made of an insulating material that is easily cut together with the filler 14, such as epoxy resin, silicone resin, phenolic resin, or fluororesin. The resin may contain a filler such as silica.

[0057] The filler 14 is manufactured by a method described below and is made of an insulating material that can be cut together with the molding die 16, such as an epoxy resin, a silicone resin, or a phenolic resin, and the resin may contain a filler such as silica. The molding die 16 and the filler 14 may be made of the same or different materials, but since the filler 14 fills a relatively narrow space, it is preferable that the filler 14 be made of a resin that has excellent fluidity before hardening.

[0058] In this embodiment, the electrode material constituting the first external electrode 51 and the second external electrode 52 is not particularly limited and may be, for example, a laminated film of a conductive paste film and a plating film. The plating layer may also have a two-layer structure, for example, a Ni plating layer (lower layer) and a Sn plating layer (upper layer).

[0059] An example of a method for manufacturing the solid electrolytic capacitor 10 will be described below with reference to the drawings.

[0060] In this embodiment, first, a molding die 160 as shown in Fig. 4 is prepared. The molding die 160 shown in Fig. 4 is a portion that will be cut in a step described below to become the molding die 16 shown in Fig. 1A, and has at least one cavity 162, and preferably two or more cavities 162. By increasing the number of cavities 162 formed in the molded body 160, the number of solid electrolytic capacitors 10 that can be molded simultaneously can be increased.

[0061] Each cavity 162 has a filling space that is open above the Z axis and surrounded by four side walls 16b that extend upward along the Z axis from the four sides of the bottom plate 16a. The top of the filling space is open, forming an upper opening. This molding die 16 is molded in advance using, for example, a molding resin.

[0062] 5A, the shape of each cavity 162 is substantially rectangular when viewed in the Z-axis direction, but is not particularly limited thereto and may be circular, elliptical, polygonal, or another shape. However, it is preferable that a pair of side corners 16c protruding toward the interior of the cavity 162 be formed at the inner corners on both sides along the Y-axis of the side wall portion 16b separating two adjacent cavities 162 along the X-axis.

[0063] 3A after cutting, which will be described later, and may have a protrusion 16 d. The surface of side wall 16 b, located between a pair of side corners 16 c in cavity 162, facing cavity 162 is recessed along the X-axis more than side corners 16 c and has a recess 16 e.

[0064] Although it is not necessary to form side corners 16c (as well as protrusions 16d) inside cavity 162, forming them provides a function of positioning in the X-axis direction when stack 11, which will be described later, is placed inside cavity 162. Furthermore, inside cavity 162, recess 16e between the pair of side corners 16c also serves as a positioning space when pouring in the conductive paste for forming paste electrode 40 shown in FIG.

[0065] Each cavity 162 preferably has at least one pair of side corners 16c, but this is not necessarily required. If one side wall 16b located along the X-axis within the cavity 162 has a pair of side walls 16c, the other side wall 16b along the X-axis does not necessarily have to have a side wall 16c. Furthermore, the pair of side walls 16c preferably have side corners 16c on both sides along the X-axis of the side wall 16b that separates adjacent cavities 162 along the X-axis. As shown in FIG. 4, adjacent cavities 162 along the Y-axis also preferably have side corners 16c.

[0066] Of the four side wall portions 16b, the side wall portions 16b parallel to the Y-axis and Z-axis are portions that will be removed by cutting in a later process, and in this embodiment, as shown in Fig. 1A, the side wall portions 16b parallel to the X-axis and Z-axis are separated by cutting and remain in the capacitor 10. In addition, the bottom plate portion 16a and the side corner portions 16c (including the protrusions 16d shown in Fig. 3A) shown in Fig. 6A also remain in the capacitor 10. By leaving the side wall portions 16b of the molding die 16 in the solid electrolytic capacitor 10, the moisture resistance and reliability of the product are improved.

[0067] 1B and 3B, all of the side wall portion 16b other than the side corner portion 16c and / or the protrusion 16d is cut away and does not remain in the capacitor 10A. In the capacitor 10A, only the bottom plate portion 16a and the side corner portion 16c (including the protrusion 16d) of the molding die 160 remain.

[0068] Before, after, or at the same time as preparing the molding die 150 shown in FIG. 4, the laminate 11 shown in FIG. 7B is prepared. The laminate 11 can be formed, for example, as shown in FIG. 7A, by sequentially stacking a plurality of capacitor elements 20 manufactured by a known method and bonding them with an adhesive 600. The adhesive 600 is preferably applied along the X-axis on the main surface (the surface with the largest area) of each element 20, and along the Y-axis on a portion of the main surface near the end 22b opposite the first element electrode 21. After hardening, the adhesive 600 becomes the adhesive layer 60 shown in FIG. 2A.

[0069] The laminate 11 shown in Fig. 7B may be assembled outside the mold 160 shown in Fig. 4 and then placed inside the cavity 162 of the mold 160 shown in Fig. 7C. Alternatively, the elements 20 may be stacked one by one or in blocks with adhesive 600 inside each cavity 162, and the laminate 11 may be assembled and placed as shown in Fig. 7.

[0070] When placing the laminate 11 inside each cavity 162, the laminate 11 is placed so that the first ends 21a of the first element electrodes 21 in the laminate 11 face the inner surface of the side wall portion 16b located on the opposite side of the recess 16e along the Y axis. In other words, the laminate 11 is placed inside the cavity 162 so that the second ends 22b of each element 20 face the recess 16e.

[0071] The number of stacked elements 20 in the laminate 11 is adjusted so that the first main surface 11a of the laminate 11 is lower along the Z axis than the upper end surface 16b1 of the side wall portion 16b. The number of stacked elements 20 in the laminate 11 is not particularly limited as long as it is one or more layers, and can be increased to five or more, ten or more, or several tens or more by increasing the height along the Z axis of the side wall portion 16b, i.e., the depth of the cavity 162.

[0072] After the laminate 11 is placed inside the cavity 162, in this embodiment, the recess 16e is filled with a conductive paste 400 as shown in Fig. 7E. The conductive paste 400 is the portion that becomes the paste electrode 40 shown in Fig. 2A and Fig. 3A, and is filled into the recess 16e so as to contact at least the second ends 22b of the second element electrodes 22 of all of the stacked elements 20.

[0073] Thereafter, an insulating filler material, such as a resin, that will become filler 14 shown in Fig. 7F is injected into the gap between side wall portion 16b and laminate 11 inside cavity 162 shown in Fig. 7E and cured, thereby forming filler 14 shown in Fig. 7F inside cavity 162 of molding die 160. Laminate 11 shown in Fig. 7E is embedded inside filler 14.

[0074] In this embodiment, the upper surface 14b1 of the filler 14 is preferably flush with the upper end surface 16b1 of the sidewall portion 16b of the molding die 160, but may be lower along the Z axis than the upper end surface 16b1. The position of the upper surface 14b1 of the filler 14 is not particularly limited as long as the filler 14 covers the first main surface 11a of the laminate 11 shown in FIG. 2A. As shown in FIG. 2A, the filler 14 may also penetrate into the gaps between the second element electrodes 22 of the element 20 along the Z axis, excluding the adhesive layer 60, or into the gap between the second main surface 11b of the laminate 11 and the bottom plate portion 16a. The filler 14 may also penetrate into the periphery of the resist film 26 or the periphery of the paste electrode 40. Furthermore, as shown in FIG. 7G, the upper end surface 16b1 of the sidewall portion 16b may also be covered by the upper surface 14b1 of the filler 14.

[0075] 5A and 6A show a mold having only two cavities 162, and FIGS. 7A to 7F show a mold having a single cavity 162, but in production it is preferable to use a mold 160 having multiple cavities 162 in the X-axis and Y-axis directions, as shown in FIGS. 4 and 8A.

[0076] As shown in Fig. 7F, after the insulating molding die 160 is filled with the insulating filler 14, the molding die 160 and the filler 14 are cut along the cutting planes Xc1, Yc1, and Yc2 as shown in Fig. 8A. The cutting plane Xc1 is a cutting plane substantially parallel to the X-axis and Z-axis, and is a cutting plane that divides the side wall portion 16b of the molding die 16 extending along the X-axis into two along the Y-axis, and is preferably a cutting plane that passes near the center line of the side wall portion 16b along the Y-axis.

[0077] The cutting line Yc1 passes through the recess 16e and is a position at which the paste electrode 40 is cut, and is determined so that the second end 22b of the element 20 is not cut, leaving the paste electrode 40 with a predetermined thickness in the X-axis direction. The cutting line Yc2 is determined so that a portion of the tip side of the first end 21a of the first element electrode is cut off along the X-axis, and so that a predetermined length of the first end 21a remains along the X-axis. The cutting line Yc2 may be a position at which the tip end 21a on which the resist film 26 is not formed is cut, or a position at which the tip end 21a on which the resist film 26 is formed is cut.

[0078] The method for cutting along these cutting surfaces Xc1, Yc1, and Yc2 is not particularly limited, and possible methods include using a dicing device, a laser device, etc. By cutting along these cutting surfaces Xc1, Yc1, and Yc2, the molding die 160 is cut as shown in Fig. 9, and an insulating molding 12 in which the molding die 16 and the filler 14 are integrated is obtained, with the laminate 11 embedded inside.

[0079] The first end surface 12a of the insulating molding 12 is a cut surface corresponding to the cut surface Yc2 shown in FIG. 8A , and the end surface 21a1 of the first element electrode 21 is exposed flush with the first end surface 12a, which is the cut surface Yc2. In FIG. 9 , a deposition film 21a2 is preferably formed on the end surface 21a1 of the first element electrode 21 by plating or the like, but this is not necessarily required. Before forming the deposition film 21a2, the end surface 21a1, together with the end surface 12a, is preferably subjected to end surface treatment such as polishing so that the entire end surface 21a1 is exposed from the end surface 12a.

[0080] 8A , the second end surface 12b of the insulating molding 12 has a cut surface corresponding to the cut surface Yc1, and the outer end surface 40a of the paste electrode 40 connected to the second element electrode 22 is exposed substantially flush with the second end surface 12b. Note that the second end surface 12b, together with the outer end surface 40a, is preferably subjected to a surface treatment such as polishing. This is to ensure that the outer end surface 40a with as large an area as possible is exposed flush with the end surface 12b.

[0081] 2A , the first end surface 12a and the second end surface 12b are covered with a first external electrode 51 and a second external electrode 52, respectively, and the electrodes 51 and 52 are electrically connected to the first end 21a of the first element electrode 21 and the paste electrode 40 connected to the second element electrode 22, respectively. Each of the electrodes 51 and 52 may be a laminated film made of a paste electrode film formed by applying a conductive paste and a plating film formed thereon. The plating film may also be a laminate of multiple plating films.

[0082] In solid electrolytic capacitor 10 of this embodiment, laminate 11 is placed inside mold 16, and then the filler that will form filler 14 is poured into cavity 162 of molded body 16, and laminate 11 is covered with insulating molded body 12, eliminating any limitations on the number of stacked elements 20 in laminate 11. This makes it easy to realize a solid electrolytic capacitor 10 with a high capacity.

[0083] Furthermore, the molding die 16 has sidewalls 16b and side corners 16c that are continuous with the bottom plate 16a and are positioned so as to directly or indirectly cover at least a portion of the side peripheral surface of the laminate 11. In this configuration, the sidewalls 16b and side corners 16c serve as positioning and guides when the laminate 11 is placed inside the molding die 16, making it possible to orderly place the laminate 11 inside the molding die 16 along the stacking direction. In other words, it becomes easy to orderly place some of the stacked elements 20 substantially parallel to the bottom plate 16a without tilting them relative to the bottom plate 16a inside the molding die 16, contributing to an increase in the number of stacked elements 20.

[0084] At the first end surface 12a of the insulating molding 12, the end surfaces 21a1 of the first ends 21a of the first element electrodes 21 of each capacitor element 20 are exposed and connected to the first external electrode 51. At the second end surface 12b of the insulating molding 12, the base electrodes 40 that are connected to integrate the second ends 22b of the second element electrodes 22 of each capacitor element 20 are exposed and connected to the second external electrode 52.

[0085] This configuration makes it possible to shorten the length of the lead-out region from the element electrode 21 or 22 of the element 20 to the external electrode 51 or 52, thereby reducing the ESR and downsizing the device 10. Furthermore, the paste electrode 40 can reliably connect the stacked second element electrodes 22 and the second external electrode 52, improving the reliability of the connection.

[0086] As shown in Fig. 3A , a pair of side corners 16c that are continuous with the bottom plate portion 16a (see Fig. 2A ) of the molding die 16 are located on both sides of the paste electrode 40 along the Y axis. This configuration makes it easier to pour the conductive paste 400 into the gap between the side corners 16c (recess 16e shown in Fig. 7E ) during manufacturing, as shown in Fig. 7E . Therefore, as shown in Fig. 2A , it is possible to easily manufacture a structure in which stacked second element electrodes 22 are connected by the paste electrode 40 along the stacking direction (direction along the Z axis).

[0087] In this embodiment, as shown in FIG. 3A , the step distance X1 of the side corner 16c relative to the second end surface 16b3 is 2 to 400 μm. This configuration facilitates the formation of a paste electrode 40 with a predetermined thickness of 2 to 400 μm. By making the thickness of the paste electrode 40 equal to or greater than the predetermined value, dimensional variations between the capacitor elements 20 and their second element electrodes 22 can be absorbed, enabling reliable connection between the second element electrodes 22 of all capacitor elements 20 and the second external electrodes 52, thereby contributing to improved reliability. Furthermore, making the thickness of the paste electrode 40 equal to or less than the predetermined value contributes to reduced ESR and cost.

[0088] 3A, in this embodiment, the width y1 between the pair of side corners 16c is smaller than the width y2 of the second element electrode 22 of the capacitor element 20, but it may be larger. In that case, the second end 22b of the second element electrode 22 may be inserted between the pair of side corners 16c and connected to the paste electrode 40 located therebetween.

[0089] In the manufacturing method of this embodiment, as shown in FIG. 7E, a recess 16e is provided on a portion of the inner wall surface of the side wall 16b of the molding die 160, and the conductive paste 400 is poured into the recess 16e. The formation of the recess 16e makes it easy to position and arrange the laminate 11 inside the molding die 160, and also makes it easy to pour the conductive paste 400 along the recess 16e. The depth of the recess 16e along the X-axis is preferably 2 to 400 μm. This configuration makes it easy to form a paste electrode 40 made of conductive paste with a predetermined thickness corresponding to the depth of the recess 16e.

[0090] In the manufacturing method of this embodiment, as shown in Fig. 5B, the side end portions 16c or protrusions 16d located on both sides of the Y axis of the recesses 16e formed on the side wall surfaces located on both sides of the X axis of the side wall portion 16b may be wedge-shaped. By using such a shape, the conductive paste 400 shown in Fig. 7E can be easily accumulated inside the recesses 16e.

[0091] Alternatively, as shown in Fig. 5C, the side end portions 16c or protrusions 16d located on both sides of the Y axis of the recess 16e formed on the side wall surface located on both sides of the X axis of the side wall portion 16b may be tapered so that the thickness decreases from the side corners 16c toward the side wall portion 16b. By using such a shape, the conductive paste 400 shown in Fig. 7E can easily flow from the inside of the recess 16e toward the side corners 16c.

[0092] Alternatively, as shown in Fig. 5D, the thickness of a pair of side corners 16c located on both sides along the Y axis or a side wall portion 16bα located between a pair of protrusions 16d may be changed along the X axis, so that the shape of the recess 16e is semicircular or semielliptical. With this configuration, similar to the shape shown in Fig. 5C, the conductive paste 400 shown in Fig. 7E can easily flow from the inside of the recess 16e toward the side corners 16c.

[0093] 5E, the thickness of the side wall portion 16bβ located between adjacent cavities 162 along the X axis may be uniform along the Y axis. That is, as shown in FIG. 8C1, for example, recesses do not need to be formed on both surfaces of the side wall portion 16bβ along the X axis.

[0094] However, in this case, it is preferable to provide a positioning member (e.g., a positioning protrusion 16a1) or a positioning mark between the end 22a of the laminate 11 shown in Figure 7E and the side wall portion 16bβ to ensure a gap for injecting the conductive paste 400, for example, by providing the positioning member or mark protruding along the Z-axis on the surface of the bottom plate portion 16a.

[0095] Alternatively, as shown in Fig. 6B, the inner wall surfaces of the sidewall portions 16bγ separating adjacent cavities 162, 162 along the X axis on the opposite side along the X axis may be tapered so that the depth of the recesses 16e along the X axis decreases toward the bottom plate portion 16a. This configuration facilitates pouring the conductive paste 400 shown in Fig. 7E from the opening side of the recesses 16e toward the bottom plate 16a. This configuration allows for easy simultaneous production of a large number of solid electrolytic capacitors.

[0096] Alternatively, as shown in FIG. 6C , a notch 16b4 may be provided along the Z axis at the top of the side wall 16bδ that separates adjacent cavities 162, 162 along the X axis, thereby connecting adjacent cavities 162, 162 along the X axis. This configuration makes it possible to simultaneously pour conductive paste 400 into two recesses 16e from above along the Z axis of the notch 16b4, as shown in FIG. 7e . Therefore, it becomes possible to simultaneously supply conductive paste 400 to two cavities 162 by performing a single application (pouring) operation of the conductive paste 400.

[0097] In the example shown in Figure 6C, side wall portion 16b4 is located below side wall portion 16bδ along the Z axis, separating adjacent cavities 162, 162 along the X axis. However, side wall portion 16b4 may be completely removed, leaving only side corner portion 16c, such that recesses 16e are completely connected along the X axis. In this case, the height of side corner portion 16c along the Z axis may be equal to or smaller than the height of side wall portion 16b along the Z axis. Furthermore, when positioning protrusion 16a1 is provided as shown in Figure 5E, side wall portion 16bβ separating two cavities 162 may be completely eliminated, and cavities 162 may be continuous with each other with the same Y-axis width as adjacent cavities 162 along the X axis. In this case, the cutting line Yc1 that cuts between the capacitor elements 20, 20 arranged side by side along the X-axis direction shown in FIG. 8C1 may be single.

[0098] 1B and 3B, solid electrolytic capacitor 10A according to this embodiment is similar to that of the first embodiment, except for the configuration of molding die 16. In the manufacturing method of this embodiment, as can be seen from a comparison between FIGS. 8A and 8B, cut surfaces Yc1 and Yc2 are similar to those of the embodiment shown in FIG. 8A, and cut surface Xc2 shown in FIG. 8B is located at a different position from cut surface Xc1 of the embodiment shown in FIG.

[0099] 8A, the cut surface Xc2 shown in Fig. 8B is located as close as possible to the inner surface of the cavity 162, between the inner surface of the side wall portion 16b separating adjacent cavities 162 along the Y axis and the side portion 22c of the second element electrode 22. The cut surface Xc2 cuts the filler 14 located inside the cavity 162, but care must be taken not to cut the side portion 22c of the second element electrode 22.

[0100] By cutting in this manner, as shown in Figures 1B and 3B, only the bottom plate portion 16a and a pair of side corner portions 16c of the mold 16 remain, and the side surface 14b4 located on the opposite side along the Y axis of the filler 14 is not surrounded by the side wall portion 16b, unlike the example shown in Figure 3A.

[0101] The solid electrolytic capacitor 10A of this embodiment can also be modified in the manner described in the first embodiment, and provides the same effects as those of the first embodiment.

[0102] As described above, solid electrolytic capacitors 10 and 10A have been described using a number of embodiments, but the present invention is not limited to these embodiments, and other combinations and variations of the embodiments are contemplated. For example, in solid electrolytic capacitor 10 of the first embodiment, etched aluminum foil is used as the valve metal in capacitor element 20, but the material and shape of the valve metal and the material and shape of the cathode portion can be selected arbitrarily as long as the problem is solved.

[0103] In the solid electrolytic capacitors 10 and 10A described above, the thin or flat elements 20 are stacked, but the elements are not limited to being thin or flat, and may be rod-shaped or block-shaped, or a combination thereof. The second element electrode may have any shape as long as it surrounds the main portion of the first external electrode, and may, for example, have a cylindrical shape with a bottom.

[0104] 8A, the side wall portion 16b separating the two cavities 162 arranged along the Y axis may be deleted, and the cavities 162 may be continuous along the Y axis, as shown in Fig. 8C2. In this case, unlike the cutting line Xc2 shown in Fig. 8B, a single cutting line Xc1 may be used to cut along the X axis between the capacitor elements 20 arranged along the Y axis.

[0105] 8D, a recess 16f may be formed in the inner wall surface of the side wall 16b that constitutes the cavity 162 of the molding die 160, together with or without the recess 16e. The formation of the recess 16f makes it easy to position and arrange the laminate 11 inside the molding die 160.

[0106] Example 1: A 3.5 mm wide aluminum foil with roughened surfaces on both sides was prepared, and a resist layer was formed on it to position the solution during immersion. The portion of the aluminum foil under the resist where the cathode layer was to be formed was immersed in a 15% aqueous solution of ammonium adipate, and a voltage was applied using the aluminum foil as the positive electrode and the aqueous solution as the negative electrode to form a predetermined oxide film, which was then washed and dried.

[0107] A conductive polymer layer (such as polyethylenedioxythiophene or polypyrrole) was formed by a predetermined method on the cathode layer formation portion, followed by a carbon paste layer and a silver paste layer, thereby obtaining a capacitor element 20.

[0108] Next, an adhesive 600 shown in FIG. 7A was applied near the second end of the second element electrode 22, which is the element cathode portion, and the elements 20 were stacked. The adhesive 600 was then heated and cured to obtain a laminate 11 having a predetermined number of layers.

[0109] A mold 160 was prepared by molding. An adhesive 600 was applied to the bottom of each cavity 162, and the laminate 11 was attached thereto. As shown in FIG. 7e, a conductive paste was poured into the recess 16e located at the cathode end of the laminate 11. A filler was injected into the cavity 162, and the laminate 11 was embedded in the insulating compact 12 by molding the filler 14.

[0110] Thereafter, the substrate was diced along the cutting planes Xc1, Yc1, and Yc2 shown in Fig. 8A into individual pieces, and then, as shown in Fig. 2A, external electrodes 51 and 52 were formed to obtain solid electrolytic capacitor 10 shown in Figs. 1A and 3A.

[0111] Example 2 Solid electrolytic capacitor 10A shown in FIGS. 1B and 3B was obtained in the same manner as in Example 1, except that the cut surfaces obtained by dicing were cut surfaces Xc2, Yc1, and Yc2 shown in FIG. 8B.

[0112] REFERENCE SIGNS LIST 10, 10A...Solid electrolytic capacitor 11...Laminate 11a...First main surface 11b...Second main surface 12...Insulating molding 12a...First end surface 12b...Second end surface 14...Filler 14a...Bottom surface 14b1...Top surface 14b2...First end surface 14b3...Second end surface 14b4...Side surface 16, 160...Mold 16a...Bottom plate portion 16a1...Positioning protrusion 16b, 16bα, 16bβ, 16bγ, 16bδ...Side wall portion 16b1...Upper end surface 16b2...First end surface 16b3...Second end surface 16b4...Notch 16c...Side corner portion 16d...Protrusion 16e, 16f...Recess 162...Cavity 20...Capacitor element DESCRIPTION OF SYMBOLS 21...First element electrode 21a...First end 21a1...End surface 21a2...End surface deposited film 21b...Second end 22...Second element electrode 22a...First end 22b...Second end 22c...Side portion 24...Solid electrolyte layer 26...Resist film 26a...Tip surface 28...Dielectric layer 40...Paste electrode 40a...Outer end surface 400...Conductive paste 51...First external electrode 52...Second external electrode 60...Adhesive layer 600...Adhesive

Claims

1. A solid electrolytic capacitor comprising: an insulating molding having an internal laminate in which one or more capacitor elements each having a solid electrolyte are stacked; a first external electrode provided on a first end face of the insulating molding; and a second external electrode provided on a second end face of the insulating molding, wherein the insulating molding has a filler covering at least one first main surface along the stacking direction of the laminate; and a molding die having at least a bottom plate portion positioned so as to directly or indirectly cover a second main surface of the laminate opposite the first main surface along the stacking direction.

2. The solid electrolytic capacitor according to claim 1, wherein the mold has a side wall or side corner portion that is continuous with the bottom plate portion and is positioned so as to directly or indirectly cover at least a portion of the side peripheral surface of the laminate.

3. A solid electrolytic capacitor as described in claim 1, wherein at a first end surface of the insulating molding, a first end of a first element electrode of each of the capacitor elements is exposed and connected to the first external electrode, and at a second end surface of the insulating molding, a paste electrode that is connected to integrate the second ends of the second element electrodes of each of the capacitor elements is exposed and connected to the second external electrode.

4. The solid electrolytic capacitor according to claim 3, wherein a pair of side corners are located on both sides of the paste electrode and are continuous with the bottom plate portion of the mold.

5. The solid electrolytic capacitor according to claim 4, wherein the step distance of the side corner from the second end face is 2 to 400 μm.

6. A solid electrolytic capacitor as described in claim 4 or 5, wherein the width between the pair of side corners is smaller than the width of the second element electrode of the capacitor element, and the second end of the second element electrode is connected to the paste electrode located between the pair of side corners.

7. A solid electrolytic capacitor as described in claim 4 or 5, wherein the width between the pair of side corners is greater than the width of the second element electrode of the capacitor element, and the second end of the second element electrode is inserted between the pair of side corners and connected to the paste electrode.

8. The solid electrolytic capacitor according to claim 1, wherein the second ends of the second element electrodes of the capacitor elements adjacent in the stacking direction in the laminate are integrally fixed to each other with a conductive or non-conductive adhesive layer.

9. A solid electrolytic capacitor as described in claim 8, wherein the adhesive layer is disposed between the second ends of the second element electrodes of the capacitor elements adjacent in the stacking direction in the laminate so as to prevent the paste electrode from entering between the second ends of the second element electrodes of the capacitor elements adjacent in the stacking direction in the laminate.

10. The solid electrolytic capacitor according to any one of claims 1 to 5, wherein the first element electrode is made of a valve metal and includes an etched metal or a sintered metal.

11. The solid electrolytic capacitor according to any one of claims 1 to 5, wherein the first element electrode is an anode and the second element electrode is a cathode.

12. A process of placing a laminate in which capacitor elements having a solid electrolyte are stacked in a cavity of an insulating mold having a bottom plate portion and a side wall portion integrated with the bottom plate portion; a process of pouring a conductive paste into the cavity of the mold in which the laminate is placed and hardening it to form a paste electrode that integrates second ends of second element electrodes of the capacitor elements in the laminate; a process of injecting an insulating material into the cavity of the mold from an opening in the side wall portion to form a filler inside the mold that covers at least one first main surface along the stacking direction of the laminate; a process of cutting an insulating molded body consisting of the mold and the filler to form a first cut surface so that first ends of first element electrodes of the capacitor elements in the laminate located inside the mold are exposed to the outside; and a process of cutting the insulating molded body to form a second cut surface so that ends of the paste electrodes located inside the mold are exposed to the outside. A method for manufacturing a solid electrolytic capacitor, comprising: a step of forming a first external electrode on a first cut surface of the insulating molding and connecting ends of the stacked plurality of first element electrodes to the first external electrode; and a step of forming a second external electrode on a second cut surface of the insulating molding and connecting the paste electrode to the second external electrode.

13. The method for manufacturing a solid electrolytic capacitor according to claim 12, wherein a recess is provided in a portion of the inner wall surface of the side wall of the molding die, and the conductive paste is poured into the recess.

14. The method for producing a solid electrolytic capacitor according to claim 13, wherein the depth of the recess is 2 to 400 μm.

15. A method for manufacturing a solid electrolytic capacitor as set forth in claim 13 or 14, wherein the inner wall surface of the side wall on which the recess is formed is tapered so that the depth of the recess becomes shallower toward the bottom plate portion.

16. The method for manufacturing a solid electrolytic capacitor according to any one of claims 12 to 14, wherein the molding die is preformed from a molding resin.

17. A method for manufacturing a solid electrolytic capacitor as described in claim 13 or 14, wherein the molding die comprises a first molding die having a first cavity corresponding to the cavity, and a second molding die molded continuously from the first molding die and having a second cavity corresponding to the cavity, wherein a first recess facing the first cavity is formed on one side wall surface of an intermediate side wall portion separating the first cavity and the second cavity, and a second recess facing the second cavity is formed on the other side wall surface of the intermediate side wall portion, and wherein the first recess and the second recess have a configuration corresponding to the recesses.

18. A method for manufacturing a solid electrolytic capacitor as described in claim 13 or 14, wherein the mold comprises a first mold having a first cavity corresponding to the cavity, and a second mold formed continuously from the first mold and having a second cavity corresponding to the cavity, and a notch is formed in an intermediate side wall portion separating the first cavity and the second cavity, allowing the conductive paste to be poured continuously between the first cavity and the second cavity.

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