Solid electrolytic capacitor

Abstract

[Problem] To have a highly reliable connection structure between a capacitor element and an external electrode. [Solution] This solid electrolytic capacitor includes: a plurality of capacitor elements extending in a first direction, each of the plurality of capacitor elements having an anode part that has a valve-metal base part and a cathode part that has a solid electrolyte layer; a coating resin part covering at least part of each of the capacitor elements in a state where the plurality of capacitor elements are arranged in a second direction; an electroconductive paste part electrically connected to the cathode part of each of the capacitor elements; a first external electrode provided to a first end surface of a laminate including the plurality of capacitor elements, the coating resin part, and the electroconductive paste part; and a second external electrode provided to a second end surface of the laminate. The first external electrode is connected to the anode part of each of the capacitor elements, and the second external electrode is indirectly connected to the cathode part of each of the capacitor elements via at least the electroconductive paste part.

Description

solid electrolytic capacitor

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

[0002] Attempts have been made to increase the capacitance of solid electrolytic capacitors by increasing the number of capacitor elements contained within them. However, in the structures of solid electrolytic capacitors proposed to date, capacitor elements are stacked and mounted on a lead frame and connected in parallel, which can lead to poor connections between the capacitor elements and the lead frame, hindering efforts to increase capacitance.

[0003] JP 2018-67572 A Japanese Patent No. 7067512 Japanese Patent No. 7300616

[0004] The present invention has been made in view of the above circumstances, and provides a solid electrolytic capacitor having a highly reliable connection structure between a capacitor element and an external electrode.

[0005] a conductive paste portion electrically connected to the cathode portion of each of the capacitor elements and made of hardened conductive paste; a first external electrode provided on a first end face, which is one end face in the first direction, of a laminate including the plurality of capacitor elements, the coating resin portion, and the conductive paste portion; and a second external electrode provided on a second end face, which is the other end face in the first direction, of the laminate, wherein the first external electrode is connected to the anode portion of each of the capacitor elements, and the second external electrode is indirectly connected to the cathode portion of each of the capacitor elements at least via the conductive paste portion.

[0006] In this type of solid electrolytic capacitor, the cathode of each capacitor element is indirectly connected to the external electrode via a conductive paste portion formed by hardening the conductive paste. The conductive paste portion absorbs dimensional variations between the capacitor element and its cathode portion, and can reliably connect the cathode portion to the second external electrode. This type of solid electrolytic capacitor can be produced using a simple process, and achieves a highly reliable connection structure between the capacitor element and the external electrode.

[0007] Furthermore, for example, the conductive paste portion may have a second direction continuous portion formed continuously in the second direction, and an inter-element portion that extends from the second direction continuous portion toward the first end face side and intersects between the cathode portions of adjacent capacitor elements.

[0008] Such a conductive paste portion forms a wide contact area with both the cathode portion of the capacitor element and the second external electrode, thereby reliably connecting the cathode portion and the second external electrode and reducing the resistance value at the connection structure between the cathode portion and the second external electrode.

[0009] Furthermore, for example, the thickness of the conductive paste defined by the average distance between the second end face of the element, which is the end face on the second end side of the capacitor element connected by the conductive paste portion, and the second external electrode may be 2 to 400 μm.

[0010] By making the thickness of the conductive paste equal to or greater than a predetermined value, it is possible to absorb dimensional variations between the capacitor element and its cathode portion, and to reliably connect the cathode portion and the second external electrode. Furthermore, by making the thickness of the conductive paste equal to or less than a predetermined value, it is possible to suppress an increase in resistance in the connection structure between the cathode portion and the second external electrode.

[0011] Furthermore, for example, the conductive paste portion may individually cover at least a portion of the element second end portion, which is the end portion on the second end face side of each of the capacitor elements, and connect the cathode portions of adjacent capacitor elements in the second direction.

[0012] Such a conductive paste portion serves to maintain the connection between the capacitor elements in the laminate, thereby increasing durability against external forces. Furthermore, because such a conductive paste portion serves to maintain the connection between the capacitor elements before the formation of the coating resin portion, it may be possible to omit structures such as adhesives that connect the capacitor elements, thereby simplifying the manufacturing process.

[0013] Furthermore, for example, the solid electrolytic capacitor according to the present disclosure may have a non-conductive paste portion that connects the cathode portions of adjacent capacitor elements and is made of hardened non-conductive paste.

[0014] Such non-conductive paste portion has a higher bonding strength than conductive adhesives and the like, and therefore can increase durability against external forces.

[0015] Furthermore, for example, the solid electrolytic capacitor according to the present disclosure may include a substrate that is disposed on one side of the laminate in the second direction and supports the laminate from the one side in the second direction.

[0016] In such a solid electrolytic capacitor, the substrate supports the laminate, thereby increasing durability against external forces.

[0017] Furthermore, for example, in the solid electrolytic capacitor according to the present disclosure, the coating resin portion may have an inner resin portion that covers at least a portion of the cathode portions of the plurality of capacitor elements and does not cover at least a portion of the conductive paste portion, and an outer resin portion that covers the inner resin portion, the capacitor elements, and at least a portion of the conductive paste portion.

[0018] Furthermore, for example, the first external electrode and the second external electrode may each include a conductive paste electrode layer made of hardened conductive paste, and a plating layer formed on the conductive paste electrode layer by plating.

[0019] Such a solid electrolytic capacitor has highly reliable conductive paths formed by a rational manufacturing process between the first and second external electrodes and the capacitor element.

[0020] Also, for example, the valve metal may be either an etched foil of aluminum or a sintered block of tantalum or niobium.

[0021] Such valve metals have good electrochemical properties for use in solid electrolytic capacitors, and therefore solid electrolytic capacitors having such valve metal portions can have improved characteristics such as capacitance.

[0022] FIG. 1 is a conceptual diagram of a solid electrolytic capacitor according to a first embodiment. FIG. 2 is an enlarged schematic cross-sectional view of one capacitor element included in the solid electrolytic capacitor shown in FIG. 1 and its surrounding structure. FIG. 3 is an enlarged cross-sectional view of the surrounding structure of the cathode part of the capacitor element shown in FIG. 2. FIG. 4 is a conceptual diagram showing a first stage in a method for manufacturing the solid electrolytic capacitor shown in FIG. 1. FIG. 5 is a conceptual diagram showing a second stage in a method for manufacturing the solid electrolytic capacitor shown in FIG. 1. FIG. 6 is a conceptual diagram showing a third stage in a method for manufacturing the solid electrolytic capacitor shown in FIG. 1. FIG. 7 is a conceptual diagram of a solid electrolytic capacitor according to a second embodiment.

[0023] The solid electrolytic capacitor according to the present disclosure will be described in detail based on specific embodiments.

[0024] First Embodiment Fig. 1 is a conceptual diagram of a solid electrolytic capacitor 10 according to the present invention. Fig. 1 shows a cross section perpendicular to a first direction D1 (X-axis direction), which is the direction in which multiple capacitor elements 20 included in the solid electrolytic capacitor 10 extend, and a second direction (Y-axis direction), which is the arrangement direction (stacking direction) of the multiple capacitor elements 20. However, the internal structure of the capacitor element 20 is not shown in Fig. 1.

[0025] 1, solid electrolytic capacitor 10 has a laminate 12 including a plurality of capacitor elements 20 (eight in the example shown in FIG. 1). In addition to the plurality of capacitor elements 20, laminate 12 also has a coating resin portion 50 that covers the capacitor elements 20, a conductive paste portion 40 that is electrically connected to cathode portions 31 (see FIG. 2) of the capacitor elements 20, and the like. Solid electrolytic capacitor 10 also has a first external electrode 71 provided on a first end face 12a, which is one end face of laminate 12 in the first direction D1 (end face in the negative X-axis direction), and a second external electrode 72 provided on a second end face 12b, which is the other end face of laminate 12 in the first direction D1 (end face in the positive X-axis direction).

[0026] Fig. 2 is an enlarged schematic cross-sectional view of one of the capacitor elements 20 included in the solid electrolytic capacitor 10 shown in Fig. 1, showing the capacitor element 20 and its surrounding structure. Note that Fig. 2 omits the coating resin portion 50, the non-end paste portion 62, and the other capacitor elements 20.

[0027] 2, capacitor element 20 has an anode portion 25 having a base portion 27 of valve metal 26 and a cathode portion 31 having a solid electrolyte layer 32, and extends in a first direction D1. Capacitor element 20 has a generally rectangular thin plate shape when viewed from the Y-axis direction, and second direction D2 (Y-axis direction) shown in FIGS. 1 and 2 is the thickness direction of capacitor element 20. Thickness T2 of capacitor element 20 is not particularly limited, but is, for example, approximately 20 to 500 μm at element second end 22, which is the end of capacitor element 20 on the second end face 12b side.

[0028] As shown in Figure 2, the anode portion 25 of the capacitor element 20 has a base portion 27 of a valve metal 26. In the solid electrolytic capacitor 10 shown in Figures 1 and 2, an etched aluminum foil is used as the valve metal 26, and the base portion 27 is made of aluminum. However, the valve metal used in the capacitor element 20 is not limited to this, and a tantalum or niobium sintered block (see Figure 7) or other valve metals can be used. By using either an etched aluminum foil or a tantalum-niobium sintered block as the valve metal 26, a solid electrolytic capacitor 10 with excellent characteristics such as capacitance can be realized.

[0029] 2 , the base portion 27 of the valve metal 26 in the capacitor element 20 extends in the first direction D1 and is exposed on the outermost surface of the capacitor element 20 at the element first end face 21 a, which is the end face on the first end face 12 a side of the capacitor element 20. The base portion 27 of the valve metal 26 constituting the anode portion 25 is directly connected to the first external electrode 71 at the element first end face 21 a.

[0030] The valve metal 26 has a dielectric layer 28 made of an aluminum oxide film formed on the surface of the base portion 27. The surface of the base portion 27 of the valve metal 26 is roughened (enlarged) to increase the surface area and become porous at the element second end portion 22, which is the end portion on the second end face 12b side of the capacitor element 20, and at the element central portion. The dielectric layer 28 is formed by subjecting the roughened surface of the base portion 27 to a chemical conversion treatment (anodization). Note that in Figures 2 and 3, the boundaries between the dielectric layer 28 and the base portion 27 and between the dielectric layer 28 and the solid electrolyte layer 32 are depicted as straight lines for simplification, but in reality they have complex shapes that follow the roughened surfaces.

[0031] It is desirable that the dielectric layer 28 is not formed on the surface of the base portion 27, which is the element first end portion 21, which is the end portion on the first end face 12a side of the capacitor element 20. The surface of the element first end portion 21, except for the element first end face 21a connected to the first external electrode 71, is covered with a resist layer 35. The resist layer 35 is formed of an insulating resin such as epoxy resin or silicone resin, and insulates the anode portion 25 and the cathode portion 31 of the capacitor element 20 from short-circuiting. Alternatively, the resist layer 35 may be omitted, and only the valve metal 26 may be formed.

[0032] 2 , cathode portion 31 of capacitor element 20 includes solid electrolyte layer 32 and cathode extraction layer 33. Cathode portion 31 is formed in a portion of capacitor element 20 excluding element first end portion 21, which is the end portion on the first end face 12 a side, so as to cover dielectric layer 28 made of an aluminum oxide film of valve metal 26.

[0033] 3 is an enlarged cross-sectional view of the structure around the cathode portion 31 of the capacitor element 20 shown in FIG. 2. The solid electrolyte layer 32 of the cathode portion 31 contains a conductive polymer compound and constitutes the inner layer of the cathode portion 31. The conductive polymer compound contained in the solid electrolyte layer 32 is not particularly limited, but examples thereof include polythiophene and polypyrrole. Although shown in a simplified form in FIGS. 2 and 3, the inner surface of the solid electrolyte layer 32 has a complex shape that penetrates into the roughened surface of the valve metal 26. The thickness of the solid electrolyte layer 32 is not particularly limited, but is, for example, about 5 to 30 μm.

[0034] 2 and 3 , cathode extraction layer 33 of cathode unit 31 is formed to cover the outside of solid electrolyte layer 32, and the inner surface of cathode extraction layer 33 is in contact with the outer surface of solid electrolyte layer 32. Cathode extraction layer 33 constitutes the outer layer of cathode unit 31. As shown in FIG. 3 , cathode extraction layer 33 according to this embodiment has graphite paste layer 33a in contact with solid electrolyte layer 32 from the outside and silver paste layer 33b in contact with graphite paste layer 33a from the outside, and exhibits a current collecting function. The thickness of graphite paste layer 33a can be, for example, approximately 3 μm, and the thickness of silver paste layer 33b can be, for example, approximately 10 μm.

[0035] 1 and 2, the conductive paste portion 40 is electrically connected to the cathode portion 31 (see FIG. 2) of each capacitor element 20. The conductive paste portion 40 is made of hardened conductive paste. For example, the conductive paste portion 40 may be a hardened silver paste portion formed by hardening a silver paste containing silver powder and a binder resin (such as an epoxy resin).

[0036] As will be understood from the manufacturing method described below, the conductive paste portion 40 is formed separately from the capacitor elements 20 so as to span across all of the capacitor elements 20 included in the laminate 12. As shown in FIG. 1 , the conductive paste portion 40 individually covers at least a portion of the element second end 22, which is the end of each capacitor element 20 on the second end face 12b side, and connects the cathode portions 31 of adjacent capacitor elements 20 in the second direction D2. Also, as shown in FIG. 1 , the conductive paste portion 40 preferably covers the entire element second end face 22a of each capacitor element 20. However, there may also be embodiments in which a portion of the element second end face 22a of the capacitor element 20 is not covered by the conductive paste portion 40.

[0037] 1 , the conductive paste portion 40 has a second direction continuous portion 41 formed continuously in the second direction D2, and an inter-element portion 42 protruding from the second direction continuous portion 41 toward the first end face 12a. The inter-element portion 42 is inserted between the element second end portions 22 on which the cathode portions 31 of adjacent capacitor elements 20 are formed, and is sandwiched between the cathode portions 31 on both sides in the second direction D2. Therefore, the inter-element portion 42 of the conductive paste portion 40 connects the cathode portions 31 of adjacent capacitor elements 20 along the second direction D2.

[0038] At least a portion of the second direction continuous portion 41 of the conductive paste portion 40 is sandwiched on both sides in the first direction D1 between the second external electrode 72 and the element second end surface 22 a of the capacitor element 20. Therefore, at least a portion of the second direction continuous portion 41 of the conductive paste portion 40 connects the second external electrode 72 and the element second end surface 22 a of the capacitor element 20 along the second direction D2. The conductive paste thickness T1 (see FIG. 2 ), which is defined by the average distance between the element second end surface 22 a of the capacitor element 20 connected by the second direction continuous portion 41 of the conductive paste portion 40 and the second external electrode 72, is not particularly limited, but is preferably, for example, 2 to 400 μm, and more preferably 5 to 100 μm.

[0039] By setting the conductive paste thickness T1 to a predetermined value or more, it is possible to absorb dimensional variations in the capacitor element 20 and its cathode portion 31, and to ensure that the conductive paste portion 40 reliably connects the cathode portion 31 and the element second end portion 22 to the second external electrode 72. Furthermore, by setting the conductive paste thickness T1 to a predetermined value or less, it is possible to suppress an increase in the resistance value in the connection structure portion between the cathode portion 31 and the second external electrode 72.

[0040] As shown in FIG. 1 , the solid electrolytic capacitor 10 has a non-end paste portion 62 that connects the cathode portions 31 of adjacent capacitor elements 20. In the embodiment shown in FIG. 1 , the non-end paste portion 62 is a non-conductive paste portion made of hardened non-conductive paste. However, the non-end paste portion 62 is not limited to being non-conductive and may be made of a conductive material such as a conductive adhesive or hardened conductive paste. The non-end paste portion 62 itself may be omitted, in which case the portion where the non-end paste portion 62 is formed may be hollow. The non-end paste portion 62 is formed near the center of the laminate 12 in the first direction D1 and connects the element centers of each capacitor element 20 in the second direction D2.

[0041] The non-end paste portion 62 is made of, for example, epoxy resin, acrylic resin, or the like. In the embodiment shown in FIG. 1 , the non-end paste portion 62 is a non-conductive paste portion and does not form a conductive path. However, it tends to have higher bonding strength than conductive adhesives, etc. Therefore, the laminate 12 and solid electrolytic capacitor 10 having the non-conductive non-end paste portion 62 can effectively increase durability against external forces. Note that, in relation to the number of layers of the capacitor element 20, if the mechanical strength of the laminate 12 is ensured by the conductive paste portion 40, the coating resin portion 50, and the substrate 64 supporting the laminate 12, the non-end paste portion 62 can be omitted. The non-end paste portion 62 may also be made of a conductive paste, such as silver paste, or an adhesive sheet.

[0042] The substrate 64 is disposed on one side in the second direction D2 (the negative Y-axis direction side) of the laminate 12, and supports the laminate 12 from at least one side in the second direction D2. The substrate 64 is connected and fixed to the laminate 12 by the coating resin portion 50 of the laminate 12, particularly the outer resin portion 52 of the coating resin portion 50. The substrate 64 is not particularly limited as long as it has the strength to support the laminate 12, and may be a resin plate, a silicon plate, a PCB substrate, or the like.

[0043] 1 , the coating resin part 50 fixes the plurality of capacitor elements 20 in an arrayed state in a second direction D2 intersecting the first direction D1. The coating resin part 50 covers at least a portion of each capacitor element 20. In the solid electrolytic capacitor 10 according to the embodiment, the coating resin part 50 has a double structure made up of an inner resin part 51 and an outer resin part 52. However, the coating resin part 50 may have a single structure made up of the outer resin part 52 made of molded resin.

[0044] It is preferable that the inner resin portion 51 covers at least a portion of the cathode portions 31 of the plurality of capacitor elements 20, but does not cover at least a portion of the conductive paste portion 40. This prevents the boundary portion between the inner resin portion 51 and the outer resin portion 52 from appearing on the second end surface 12b of the laminate 12, and improves the shielding ability of the capacitor elements 20 from the external environment. For the same reason, it is also preferable that the inner resin portion 51 does not cover at least a portion of the resist layer 35 and the valve metal 26 of the plurality of capacitor elements 20.

[0045] The outer resin part 52 covers the inner resin part 51, the capacitor element 20, and at least a part of the conductive paste part 40. The outer resin part 52 entirely covers the other structures included in the laminate 12, such as the capacitor element 20, except for the parts where the laminate 12 is connected to the substrate 64, the first external electrode 71, and the second external electrode 72.

[0046] The inner resin portion 51 and the outer resin portion 52 are made of, for example, epoxy resin, phenolic resin, fluororesin, etc. As shown in Fig. 1 , by providing the coating resin portion 50 with a double structure of the inner resin portion 51 and the outer resin portion 52 as in the embodiment, the cathode portion 31 of the capacitor element 20, etc., coated by the inner resin portion 51, can be more effectively shielded from the outside air.

[0047] The first external electrode 71 is provided on the first end surface 12a of the laminate 12 and is connected to the anode portion 25 (see FIG. 2) of each capacitor element 20. The first external electrode 71 is directly connected to the base portion 27 of the valve metal 26 of all capacitor elements 20 included in the laminate 12 at the element first end surface 21a. In this manner, the first external electrode 71 is preferably directly connected to the anode portion 25 of each capacitor element 20. Note that, in addition to the configuration shown in FIGS. 1 and 2, configurations in which the first external electrode 71 is directly connected to the anode portion 25 of the capacitor element 20 also include a configuration (see FIG. 7) in which the anode portion 25 has a connecting member at the element first end portion 21 that connects to the base portion 27.

[0048] 1 , the first external electrode 71 has a first external electrode continuous portion 71a formed continuously on the first end surface 12a of the laminate 12, and a first external electrode discontinuous portion 71b formed in a portion of the first end surface 12a where the element first end surface 21a is exposed. The first external electrode discontinuous portion 71b is interposed between the element first end surface 21a and the first external electrode continuous portion 71a to connect them, and can have a two-layer structure, for example, a Ni-plated layer (lower layer) and an Ag or Au-plated layer (upper layer). The first external electrode continuous portion 71a covers the first external electrode discontinuous portion 71b and the remaining portion of the first end surface 12a of the laminate 12, and is formed, for example, by a layer of hardened conductive paste such as Ag paste. Furthermore, although not shown in Figure 1, the first external electrode 71 may further have a conductive plating layer such as a Ni plating layer that is formed on the first external electrode continuous portion 71a and constitutes the outermost layer of the first external electrode 71.

[0049] The second external electrode 72 is provided on the second end surface 12b of the laminate 12 and is indirectly connected to the cathode portion 31 (see FIG. 2 ) of each capacitor element 20 at least via the conductive paste portion 40. That is, as shown in FIG. 1 , the conductive paste portion 40 is interposed between the second external electrode 72 and the second end surface 22a of the capacitor element 20. The conductive paste portion 40 absorbs dimensional variations between the capacitor elements 20 and their cathode portions 31, reliably connecting the cathode portions 31 to the second external electrode 72 and ensuring an appropriate electrical conduction path. Therefore, this solid electrolytic capacitor 10 can be manufactured using a simple process and provides a highly reliable connection structure between the capacitor elements 20 and the second external electrode 72.

[0050] Unlike the second external electrode 72, the first external electrode 71 is directly connected to the anode portion 25. As shown in FIG. 2 , unlike the cathode portion 31, which has a multilayer structure, the anode portion 25 is composed of a base portion 27 extending in the first direction D1. Therefore, as will be described in the manufacturing method later, the position of the element first end surface 21 a can be easily aligned with the position of the first end surface 12 a of the laminate 12 by the cutting process of the laminate 12. Therefore, by directly connecting the first external electrode 71 to the anode portion 25, the manufacturing process can be simplified. In the embodiment, the conductive paste portion 40 is formed before the external resin portion 52 and becomes part of the laminate 12, and the first external electrode 71 and the second external electrode 72 are formed on the side surfaces of the laminate 12 later.

[0051] The second external electrode 72 includes a conductive paste layer formed by hardening a conductive paste containing, for example, Ag, from the viewpoint of adhesion to the electrode layer of the conductive paste portion 40 exposed at the second end surface 12b. The second external electrode 72 is continuously formed on the second end surface 12b of the laminate 12 and connects to the conductive paste portion 40 exposed at the second end surface 12b. Although not shown in FIG. 1 , the second external electrode 72 may further include a conductive plating layer, such as a Ni plating layer, formed on the conductive paste layer and constituting the outermost layer of the second external electrode 72. In this manner, the first external electrode 71 and the second external electrode 72 may include a conductive paste electrode layer formed of a hardened conductive paste and a plating layer formed by plating on the conductive paste electrode layer. This solid electrolytic capacitor 10 has a highly reliable conduction path formed by a streamlined manufacturing process between the first external electrode 71, the second external electrode 82, and the capacitor element 20.

[0052] An example of a method for manufacturing solid electrolytic capacitor 10 will be described below with reference to Figures 4 to 6. In manufacturing solid electrolytic capacitor 10, first, the required number (eight in this embodiment) of capacitor element materials 120, which will become capacitor elements 20 after lamination, are prepared and laminated to form conductive paste portion 40. Figure 4 is a conceptual diagram showing the process of forming conductive paste portion 40 in solid electrolytic capacitor 10.

[0053] The capacitor element material 120, which will become the capacitor element 20 (see FIG. 2 ) after lamination, is manufactured by, for example, chemically treating an aluminum foil (base portion 27), forming a resist layer 35 in a predetermined location, and then forming a cathode portion 31 on the surface of a dielectric layer 28 composed of an aluminum oxide film formed by the chemical treatment. The solid electrolyte layer 32 of the cathode portion 31 is formed by immersing the roughened surface of the dielectric layer in a liquid that becomes a conductive polymer that will become the solid electrolyte, followed by drying. A dispensing method, a screen printing method, a spray coating method, or the like may also be used. The cathode extraction layer 33 is formed on the surface of the solid electrolyte layer 32 by a screen printing method, a dipping method, a spray coating method, or the like.

[0054] As shown in FIG. 4 , the prepared capacitor element material 120 is stacked with the anode portion 25 and the cathode portion 31 aligned, and then the second end portion 22 of the element is immersed in a paste liquid 140 and dried to form a conductive paste portion 40 that covers at least a portion of the second end portion 22 of the element. A dispensing method, a spray coating method, or the like may also be used. The capacitor element material 120 has an exposed portion of the base portion 27 that was removed by cutting in the capacitor element 20 shown in FIG. 2 . Furthermore, by connecting the individual capacitor element materials 120 to each other with the non-end paste portion 62 before forming the conductive paste portion 40, it is possible to prevent the capacitor element material 120 from shifting in position during the process of forming the conductive paste portion 40.

[0055] Next, the aggregate 112 of the capacitor element material 120 on which the conductive paste portion 40 has been formed is placed on a plate 164 that will become the substrate 64 after cutting. The formation of the conductive paste portion 40 shown in FIG. 4 may be performed by dispensing after the conductive paste portion 40 is placed on the plate 164. After the conductive paste portion 40 is placed on the plate 164, the coating resin portion 50 (see FIG. 1) is formed. FIG. 5 is a conceptual diagram illustrating the coating resin portion 50 formation process in the manufacturing process of the solid electrolytic capacitor 10. As shown in the upper part of FIG. 5 , in the coating resin portion 50 formation process, an uncured resin is first applied to each aggregate 112 to form an inner resin portion 51. The upper right diagram of FIG. 5 is a conceptual diagram of the aggregate 112 of the capacitor element material 120 immediately after the inner resin portion 51 has been formed, viewed from a direction perpendicular to the first direction D1 and the second direction D2. The inner resin portion 51 is formed so that the resist layer 35, the base portion 27, and a portion of the conductive paste portion 40 are exposed from the inner resin portion 51.

[0056] Next, as shown in the lower left of Fig. 5 , a resin portion that will become the outer resin portion 52 after cutting is formed so as to cover the entire assembly 112 of capacitor element material 120 arranged on the plate material 164 and the inner resin portion 51. The outer resin portion 52 is formed by, for example, compression molding or transfer molding. After the coating resin portion 50 is formed as shown in Fig. 5 , it is cut into individual pieces to obtain the laminate 12 supported by the substrate 64 as shown in Fig. 6 .

[0057] FIG. 6 is a conceptual diagram illustrating the process of forming the second external electrode 72 in the manufacturing process of the solid electrolytic capacitor 10. As shown in FIG. 6, the second end surface 12b of the laminate 12 is immersed in an electrode paste liquid 172 to form the second external electrode 72 covering the second end surface 12b. The first external electrode 71 is formed in the same manner on the first end surface 12a of the laminate 12. However, for the first end surface 12a of the laminate 12, before immersing it in the electrode paste liquid 172 as shown in FIG. 6 to form the first external electrode continuous portion 71a, the first external electrode discontinuous portion 71b covering the element first end surface 21a is formed by plating or the like. If necessary, a conductive plating layer such as a Ni plating layer is formed on the outermost surfaces of the first external electrode 71 and the second external electrode 72. In this manner, the solid electrolytic capacitor 10 shown in FIG. 1 is obtained.

[0058] The cutting position when cutting out the laminate 12 is adjusted so that the conductive paste portion 40 is exposed at the second end surface 12b of the laminate 12 and the element second end portion 22 is not exposed. The cutting position when cutting out the laminate 12 is adjusted so that the resist layer 35 and the base portion 27 (see FIG. 2 ) are exposed at the first end surface 12a of the laminate 12.

[0059] 1 , the cathode portion 31 of each capacitor element 20 is indirectly connected to the second external electrode 72 via the conductive paste portion 40. The conductive paste portion 40 absorbs dimensional variations between the capacitor elements 20 and their cathode portions 31, reliably connecting the cathode portion 31 to the second external electrode 72 and ensuring a conductive path. Therefore, such a solid electrolytic capacitor 10 can be manufactured using a simple process and provides a highly reliable connection structure between the capacitor elements 20 and the second external electrode 72.

[0060] While the solid electrolytic capacitor according to the present disclosure has been described above using an embodiment, it goes without saying that other embodiments and modifications are included within the technical scope of the solid electrolytic capacitor according to the present disclosure. For example, in the solid electrolytic capacitor 10 shown in FIG. 1, an etched aluminum foil is used as the valve metal of the 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 can be solved.

[0061] Second Embodiment For example, FIG. 7 is a conceptual diagram showing a solid electrolytic capacitor 210 according to a second embodiment, with internal capacitor elements 220 and conductive paste portions 240 shown in perspective. The solid electrolytic capacitor 210 has a laminate 212 including a plurality of capacitor elements 220 (two in the example shown in FIG. 7 ). In addition to the plurality of capacitor elements 220, the laminate 212 also has a coating resin portion 250 that covers the capacitor elements 220, a conductive paste portion 240 that electrically connects to the cathode portions 231 (see FIG. 2 ) of the capacitor elements 220, and the like. Regarding the solid electrolytic capacitor 210 according to the second embodiment, only the differences from the solid electrolytic capacitor 10 according to the first embodiment will be described, and a description of the commonalities with the solid electrolytic capacitor 10 will be omitted.

[0062] The solid electrolytic capacitor 210 also has a first external electrode 271 provided on a first end face 212a, which is one end face of the laminate 212 in the first direction D1 (end face in the negative X-axis direction), and a second external electrode 272 provided on a second end face 212b, which is the other end face of the laminate 212 in the first direction D1 (end face in the positive X-axis direction).

[0063] The capacitor element 220 of the solid electrolytic capacitor 210 according to the second embodiment is composed of a sintered block of tantalum, which is a valve metal. The capacitor element 220 has an anode portion 225 composed of a tantalum base portion 227 and a connecting member 229, and a cathode portion 231 formed to cover the sintered block. The connecting member 229 is composed of, for example, a highly conductive metal. The material of the cathode portion 231 is the same as that of the cathode portion 31 shown in FIG. 2. As with the coating resin portion 50 shown in FIG. 1, the coating resin portion 250 fixes a plurality of capacitor elements 220 in an array in a second direction D2 intersecting the first direction D1.

[0064] The first external electrode 271 is provided on the first end surface 212a of the laminate 212, and is connected to the anode portion 25 of each capacitor element 220. The first external electrode 271 is directly connected to the connecting members 229 of the anode portions 225 of all capacitor elements 220 included in the laminate 212, at the first end surfaces 221a of those elements.

[0065] On the other hand, the second external electrode 272 is provided on the second end surface 212b of the laminate 212, and is indirectly connected to the cathode portion 231 of each capacitor element 220 at least via the conductive paste portion 240. That is, the conductive paste portion 240 is interposed between the second external electrode 272 and the element second end surface 222a of the capacitor element 220. Note that the material of the conductive paste portion 240 may be the same as that of the conductive paste portion 40 shown in FIG. 1 .

[0066] As shown in FIG. 7 , in a solid electrolytic capacitor 210 using a tantalum sintered block as the valve metal of a capacitor element 220, the cathode portion 231 of the capacitor element 220 is indirectly connected to the second external electrode 272 via a conductive paste portion 240. The conductive paste portion 240 absorbs dimensional variations between the capacitor element 220 and its cathode portion 231, reliably connecting the cathode portion 231 to the second external electrode 272 and ensuring a conductive path. Therefore, like the solid electrolytic capacitor 10, the solid electrolytic capacitor 210 can be manufactured using a simple process and provides a highly reliable connection structure between the capacitor element 220 and the second external electrode 272. Furthermore, the solid electrolytic capacitor 210, with respect to the commonalities with the solid electrolytic capacitor 10, achieves the same effects as the solid electrolytic capacitor 10.

[0067] REFERENCE SIGNS LIST 10, 210...Solid electrolytic capacitor 12, 212...Laminate 12a, 212a...First end surface 12b, 212b...Second end surface 20, 220...Capacitor element T2...Thickness 21...Element first end surface 21a, 221a...Element first end surface 22...Element second end surface 22a, 222a...Element second end surface 25, 225...Anode portion 26...Valve metal 27, 227...Base portion 28...Dielectric layer 31, 231...Cathode portion 32...Solid electrolyte layer 33...Cathode extraction layer 33a...Graphite paste layer 33b...Silver paste layer 35...Resist layer 40, 240...Conductive paste portion 41...Second direction continuous portion 42...Inter-element portion T1...Conductive paste thickness 50...Coating resin portion 51...Inner resin portion 52: Outer resin portion 62: Non-end paste portion 64: Substrate 71, 271: First external electrode 71c: Undercoat layer 71b: Intermediate layer 71a: Surface layer 72, 272: Second external electrode 120: Capacitor element material 140: Paste liquid 164: Plate material 112: Assembly 172: Electrode paste liquid 229: Connection member

Claims

1. A solid electrolytic capacitor comprising: a plurality of capacitor elements extending in a first direction, the plurality of capacitor elements having an anode portion having a base portion made of a valve metal and a cathode portion having a solid electrolyte layer; a coating resin portion covering at least a portion of each of the plurality of capacitor elements when the plurality of capacitor elements are arranged in a second direction intersecting the first direction; a conductive paste portion made of hardened conductive paste and electrically connected to the cathode portion of each of the capacitor elements; a first external electrode provided on a first end face which is one end face in the first direction of a laminate including the plurality of capacitor elements, the coating resin portion, and the conductive paste portion; and a second external electrode provided on a second end face which is the other end face in the first direction of the laminate, the first external electrode being connected to the anode portion of each of the capacitor elements, and the second external electrode being indirectly connected to the cathode portion of each of the capacitor elements at least via the conductive paste portion.

2. The solid electrolytic capacitor as described in claim 1, wherein the conductive paste portion has a second direction continuous portion formed continuously in the second direction, and an inter-element portion extending between the cathode portions of adjacent capacitor elements from the second direction continuous portion toward the first end face side.

3. The solid electrolytic capacitor according to claim 1, wherein the conductive paste thickness defined by the average distance between the second end face of the element, which is the end face on the second end face side of the capacitor element connected by the conductive paste portion, and the second external electrode is 2 to 400 μm.

4. The solid electrolytic capacitor described in claim 1, wherein the conductive paste portion individually covers at least a portion of the element second end portion, which is the end portion on the second end face side of each of the capacitor elements, and connects the cathode portions of adjacent capacitor elements in the second direction.

5. The solid electrolytic capacitor according to claim 1, further comprising a non-conductive paste portion which connects the cathode portions of adjacent capacitor elements and which is made of a hardened non-conductive paste.

6. The solid electrolytic capacitor according to claim 1, further comprising a substrate supporting the laminate from at least one side in the second direction.

7. The solid electrolytic capacitor described in claim 1, wherein the covering resin portion comprises an inner resin portion that covers at least a portion of the cathode portions of the plurality of capacitor elements and does not cover at least a portion of the conductive paste portion, and an outer resin portion that covers the inner resin portion, the capacitor elements, and at least a portion of the conductive paste portion.

8. The solid electrolytic capacitor as described in claim 1, wherein the first external electrode and the second external electrode each include a conductive paste electrode layer made of hardened conductive paste, and a plating layer formed by plating on the conductive paste electrode layer.

9. The solid electrolytic capacitor of claim 1, wherein the valve metal is one of an etched foil of aluminum and a sintered block of tantalum or niobium.