Solid electrolytic capacitor

Abstract

A solid electrolytic capacitor element according to the present disclosure comprises: at least one capacitor element including an anode part and a cathode part that extends in a first direction from the anode part; a lead frame electrically connected to the cathode part; an exterior body sealing the at least one capacitor element and the lead frame; a first external electrode electrically connected to the anode part at a first end surface on one side of the exterior body in the first direction; and a second external electrode electrically connected to the lead frame at a second end surface on the other side of the exterior body in the first direction. The lead frame includes: a side wall section that extends along the second end surface of the exterior body and faces a terminal surface of the cathode part in the first direction; and a projecting part that intersects the side wall section, extends toward the second end surface of the exterior body, and is exposed at the second end surface. The lead frame is electrically connected to the second external electrode via the projecting part.

Description

solid electrolytic capacitor

[0001] The present invention relates to a solid electrolytic capacitor, and more specifically to a solid electrolytic capacitor having a current collecting structure at least on the side end face side of a cathode part of a capacitor element.

[0002] A solid electrolytic capacitor includes, for example, at least one capacitor element and an exterior body that seals the capacitor element. The capacitor element includes, for example, an anode portion, a dielectric layer that covers at least a portion of the anode portion, and a cathode portion that covers at least a portion of the dielectric layer. Known examples of such solid electrolytic capacitors include those disclosed in Patent Documents 1 and 2 listed below.

[0003] The following Patent Document 1 describes a solid electrolytic capacitor including a capacitor element, a cathode lead frame on which the cathode portion of the capacitor element is mounted, an anode lead frame on which the anode portion of the capacitor element is mounted, a cathode terminal on which the cathode lead frame is mounted, an anode terminal on which the anode lead frame is mounted, and an exterior housing that covers the capacitor element, the cathode lead frame, the anode lead frame, the cathode terminal, and the anode terminal. The following Patent Document 1 also describes placing the capacitor element on the cathode lead frame with the side end surface of the cathode portion positioned by a guide portion, and arranging the guide portion inside the exterior housing with a sufficient distance from the side end surface of the exterior housing. That is, the following Patent Document 1 describes providing a sufficient distance between the side end surface of the cathode portion of the capacitor element and the side end surface of the exterior housing within the exterior housing.

[0004] Patent Document 2 below describes a solid electrolytic capacitor including a capacitor element, an exterior housing that covers the capacitor element so as to expose side end faces of the anode portion and the cathode portion, a first current collector arranged on one side end face of the exterior housing to be connected to the side end face of the anode portion, a second current collector arranged on the other side end face of the exterior housing to be connected to the side end face of the cathode portion, an anode lead portion having a first connection portion connected to the first current collector inside the exterior housing and a first lead portion connected to the first connection portion and extending to the outside of the exterior housing, and a cathode lead portion having a second connection portion connected to a second current collector inside the exterior housing and a second lead portion connected to the second connection portion and extending to the outside of the exterior housing. Patent Document 2 below also describes that the first lead portion of the anode lead portion and the second lead portion of the cathode lead portion are formed in an L shape so as to extend along the bottom end face of the exterior housing and then along the side end faces of the exterior housing.

[0005] Patent No. 5095107 Patent No. 6975915

[0006] As described above, in the solid electrolytic capacitor of Patent Document 1, the guide portion is positioned sufficiently away from the side end face of the exterior body, so there is excess space on the side end face of the exterior body. The existence of such excess space requires that the size of the capacitor element placed inside the exterior body be reduced by the amount of the excess space. Furthermore, if the size of the capacitor element is reduced, the capacitance of the solid electrolytic capacitor also decreases.

[0007] Furthermore, in the solid electrolytic capacitor of Patent Document 2, as described above, the first connection portion of the anode lead portion and the second connection portion of the cathode lead portion are disposed inside the exterior body, resulting in excess space on the lower end surface of the exterior body. The presence of such excess space reduces the number of capacitor elements stacked in the height direction of the exterior body by the amount of excess space. Furthermore, reducing the number of capacitor elements disposed inside the exterior body also reduces the capacitance of the solid electrolytic capacitor.

[0008] However, from the viewpoint of the surplus space inside the exterior body, it is difficult to say that sufficient consideration has been given to increasing the capacitance of the solid electrolytic capacitor.

[0009] Therefore, an object of the present disclosure is to provide a solid electrolytic capacitor that can increase the capacitance.

[0010] One aspect of the present invention relates to a solid electrolytic capacitor comprising: at least one capacitor element having an anode portion and a cathode portion extending in a first direction from the anode portion; a lead frame electrically connected to the cathode portion; an exterior housing sealing the at least one capacitor element and the lead frame; a first external electrode electrically connected to the anode portion at a first end face on one side of the exterior housing in the first direction; and a second external electrode electrically connected to the lead frame at a second end face on the other side of the exterior housing in the first direction, wherein the lead frame has a side wall portion extending along the second end face of the exterior housing and facing an end face of the cathode portion in the first direction, and a protrusion portion that intersects the side wall portion, extends toward the second end face of the exterior housing, and is exposed at the second end face, and the lead frame is electrically connected to the second external electrode via the protrusion portion.

[0011] According to the present disclosure, a solid electrolytic capacitor capable of increasing capacitance can be provided.

[0012] 2B is a cross-sectional view showing the configuration of a capacitor element according to an embodiment of the present disclosure; FIG. 2C is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to a first embodiment of the present disclosure; FIG. 2D is a plan view of the solid electrolytic capacitor as viewed from above; FIG. 2E is a plan view showing the solid electrolytic capacitor according to the first embodiment of the present disclosure as viewed from the second end face of the exterior body before a second external electrode is attached; FIG. 2F is a plan view of a lead frame as viewed from above; FIG. 2G is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to a third embodiment of the present disclosure; FIG. 2H is a plan view showing the solid electrolytic capacitor according to the third embodiment of the present disclosure as viewed from the second end face of the exterior body before a second external electrode is attached; FIG. 2H is a side cross-sectional view showing the configuration of a solid electrolytic capacitor according to a fourth embodiment of the present disclosure; FIG. 2K is a plan view of the solid electrolytic capacitor as viewed from above. FIG. 10 is a plan view showing the solid electrolytic capacitor according to the fourth embodiment of the present disclosure as viewed from the second end face side of the exterior package before the second external electrode is attached.

[0013] Below, embodiments of the present disclosure will be described using examples, but the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be exemplified, but other numerical values, materials, etc. may be applied as long as the effects of the present disclosure are obtained. Note that known components may be applied to components characteristic of the present disclosure. In this specification, when a "range from numerical value A to numerical value B" is mentioned, the range includes numerical value A and numerical value B.

[0014] In the following description, when lower and upper limits of numerical values ​​relating to specific physical properties, conditions, etc. are exemplified, any of the exemplified lower limits and any of the exemplified upper limits can be arbitrarily combined, as long as the lower limit is not equal to or greater than the upper limit. When multiple materials are exemplified, one of them can be selected and used alone, or two or more can be used in combination, unless otherwise specified.

[0015] The present disclosure encompasses any combination of two or more claims arbitrarily selected from the appended claims, i.e., any combination of two or more claims arbitrarily selected from the appended claims can be combined unless a technical contradiction arises.

[0016] [Solid Electrolytic Capacitor] A solid electrolytic capacitor according to an embodiment of the present disclosure includes at least one capacitor element having an anode portion and a cathode portion extending from the anode portion in a first direction, a lead frame electrically connected to the cathode portion, an exterior body sealing the at least one capacitor element and the lead frame, a first external electrode electrically connected to the anode portion at a first end face on one side of the exterior body in the first direction, and a second external electrode electrically connected to the lead frame at a second end face on the other side of the exterior body in the first direction.

[0017] 1 , capacitor element 10 includes anode portion 11, dielectric layer 12 covering at least a portion of anode portion 11, solid electrolyte layer 13 covering at least a portion of dielectric layer 12, and cathode extraction layer 14 covering at least a portion of solid electrolyte layer 13. In capacitor element 10, for example, solid electrolyte layer 13 and cathode extraction layer 14 form cathode portion 15. With the above configuration, capacitor element 10 has anode portion 11 and a cathode portion extending from anode portion 11 in first direction D1. Note that first direction D1 is a direction parallel to a main surface of anode portion 11.

[0018] 1 , anode portion 11 is covered with dielectric layer 12 so that one side in first direction D1 is exposed. That is, in the example shown in Fig. 1 , anode portion 11 has a covered portion C covered with dielectric layer 12 and an uncovered portion NC that is not covered with dielectric layer 12. Preferably, an insulating separation portion (insulating region, not shown) is formed in a portion of uncovered portion NC adjacent to cathode portion 15 so as to cover the surface of anode portion 11 in a strip shape, thereby restricting contact between anode portion 11 and cathode portion 15.

[0019] The anode portion 11 may be formed of an anode body made of a valve metal. Examples of the valve metal constituting the anode body include aluminum, tantalum, niobium, and titanium. The anode body may be a valve metal foil or a sintered body of valve metal particles. When the anode body is a valve metal foil, the foil may be etched from the outer surface toward the center. That is, an etched layer (porous portion) may be formed on the surface layer of the foil.

[0020] The dielectric layer 12 may be made of an oxide (e.g., aluminum oxide) formed on the surface of the anode body by a liquid phase method such as anodization, or a gas phase method such as vapor deposition or atomic layer deposition.

[0021] The solid electrolyte layer 13 is formed on the surface of the dielectric layer 12. The solid electrolyte layer 13 contains, for example, a conductive polymer. The solid electrolyte layer 13 may further contain a dopant in addition to the conductive polymer.

[0022] Examples of conductive polymers include known polymers used in solid electrolytic capacitors, such as π-conjugated conductive polymers. Examples of conductive polymers include polymers with a basic skeleton of polypyrrole, polythiophene, polyaniline, polyfuran, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, and polythiophene vinylene. Of these, polymers with a basic skeleton of polypyrrole, polythiophene, or polyaniline are preferred. The above polymers also include homopolymers, copolymers of two or more monomers, and derivatives thereof (e.g., substituted products having substituents). For example, polythiophenes include poly(3,4-ethylenedioxythiophene). Conductive polymers may be used alone or in combination of two or more.

[0023] The dopant may be, for example, at least one selected from the group consisting of low molecular weight anions and polyanions. Examples of low molecular weight anions include sulfate ions, nitrate ions, phosphate ions, borate ions, organic sulfonate ions, and carboxylate ions. Examples of dopants that form with organic sulfonate ions include benzenesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid. Examples of polyanions include polymeric polysulfonic acids and polymeric polycarboxylic acids. Examples of polymeric polysulfonic acids include polyvinylsulfonic acid, polystyrenesulfonic acid, polyallylsulfonic acid, polyacrylicsulfonic acid, and polymethacrylicsulfonic acid. Examples of polymeric polycarboxylic acids include polyacrylic acid and polymethacrylic acid. Examples of polyanions include polyestersulfonic acid and phenolsulfonic acid novolac resin. However, polyanions are not limited to the above examples.

[0024] The solid electrolyte layer 13 may further contain known additives and known conductive materials other than conductive polymers, as needed. Examples of such conductive materials include at least one selected from the group consisting of conductive inorganic materials such as manganese dioxide and TCNQ (tetracyanoxydimethane) complex salts.

[0025] The cathode extraction layer 14 may be composed of a carbon layer (not shown) formed on the surface of the solid electrolyte layer 13 and a conductor layer (not shown) formed on the surface of the carbon layer. The conductor layer may be composed of a metal paste layer containing metal particles, or a silver paste layer. The silver paste layer may be composed of, for example, a composition containing silver particles and a resin component (binder resin). The resin component may be either a thermoplastic resin or a thermosetting resin, but a thermosetting resin is preferably used. Examples of thermosetting resins include imide resins and epoxy resins.

[0026] First Embodiment Next, a solid electrolytic capacitor according to a first embodiment of the present disclosure will be described with reference to Figures 2A to 2C. In the example shown in Figures 2A to 2C, the solid electrolytic capacitor 100 includes a plurality of capacitor elements 10. Specifically, as shown in Figure 2A, in the solid electrolytic capacitor 100, the plurality of capacitor elements 10 are stacked in the height direction with their main surfaces overlapping each other. Also, as shown in Figure 2A, in the solid electrolytic capacitor 100, the plurality of capacitor elements 10 are stacked such that the protruding end faces Sa of the anode portions 11 and the terminal faces Sc of the cathode portions 15 face the same direction in the first direction D1.

[0027] The solid electrolytic capacitor 100 of the first embodiment comprises a lead frame 110 electrically connected to each of the cathode portions 15 of the plurality of capacitor elements 10, an outer casing 120 that seals the plurality of capacitor elements 10 and the lead frame 110, a first external electrode 130 electrically connected to each of the anode portions 11 of the plurality of capacitor elements 10 at a first end face E1 on one side of the outer casing 120 in the first direction D1, and a second external electrode 140 electrically connected to the lead frame 110 at a second end face E2 on the other side of the outer casing 120 in the first direction D1.

[0028] The exterior body 120 may be a resin exterior body or another exterior body. The first external electrode 130 and the second external electrode 140 can be obtained by applying a conductive paste containing conductive particles (e.g., silver particles) to the first end face E1 and the second end face E2 of the exterior body 120, drying the paste to form a conductive paste layer, and then plating a metal (e.g., nickel) on the conductive paste layer to form a metal plating layer. In the solid electrolytic capacitor 100, the first external electrode 130 is configured to cover the first end face E1 of the exterior body 120, and the second external electrode 140 is configured to cover the second end face E2 of the exterior body 120.

[0029] In the solid electrolytic capacitor 100 according to the first embodiment, the lead frame 110 has a sidewall portion 111 that extends along the second end face E2 of the exterior body 120 and faces the terminal end face Sc of the cathode portion 15 in the first direction D1, and an overhang portion 112 that intersects the sidewall portion 111, extends toward the second end face E2 of the exterior body 120, and is exposed at the second end face E2. The lead frame 110 is electrically connected to the second external electrode 140 via the overhang portion 112. In other words, at the second end face E2 of the exterior body 120, the protruding end surface Ss of the overhang portion 112 of the lead frame 110 is exposed and electrically connected to the second external electrode 140.

[0030] By configuring the lead frame 110 as described above, it is possible to design the length L of the protruding portion 112 to be as small as possible. This reduces the excess space formed between the second end surface E2 of the exterior body 120 and the side wall portion 111 of the lead frame 110, allowing the size of the capacitor element 10 to be placed inside the exterior body 120 to be increased. As a result, the capacitance of the solid electrolytic capacitor 100 can be increased. Furthermore, since the lead frame 110 has the side wall portion 111, it is possible to prevent the end surface Sc of the cathode portion 15 from coming too close to the second end surface E2 of the exterior body 120.

[0031] The length L of the protruding portion 112 is preferably 0.60 mm or less, and more preferably 0.40 mm or less. The lower limit of the length L of the protruding portion 112 is usually 0.15 mm. The protruding portion 112 includes a first protruding portion 112A and a second protruding portion 112B, which will be described later.

[0032] The side wall portion 111 of the lead frame 110 and the plurality of capacitor elements 10 are connected by a first conductive paste layer (not shown). This allows electrical connection between each of the cathode portions 15 of the plurality of capacitor elements 10 and the side wall portion 111 of the lead frame 110. More specifically, the side wall portion 111 of the lead frame 110 can be electrically connected to each of the end faces Sc of the cathode portions 15 of the plurality of capacitor elements 10. The second end face E2 of the exterior body 120 and the second external electrode 140 are also connected by a second conductive paste layer. This allows electrical connection between the second external electrode 140 and the protruding portion 112 of the lead frame 110. The first conductive paste layer and the second conductive paste layer can be formed using various known conductive adhesives.

[0033] In the solid electrolytic capacitor 100 according to the first embodiment, the anode portion 11 has a protruding end surface Sa exposed at the first end surface E1 of the exterior body 120. The anode portion 11 is electrically connected to the first external electrode 130 via the protruding end surface Sa. In other words, the protruding end surface Sa of the anode portion 11 is exposed at the first end surface E1 of the exterior body 120 and electrically connected to the first external electrode 130. Specifically, the first end surface E1 of the exterior body 120 and the first external electrode 130 are connected by a third conductive paste layer (not shown). The solid electrolytic capacitor 100 configured as described above can prevent excess space from being formed between the protruding end surface Sa of the anode portion 11 and the first end surface E1 of the exterior body 120. This allows the size of the capacitor element 10 disposed inside the exterior body 120 to be further increased. As a result, the capacitance of the solid electrolytic capacitor 100 can be further increased.

[0034] In the solid electrolytic capacitor 100 according to the first embodiment, the lead frame 110 includes a pair of first protruding portions 112A spaced apart from each other as the protruding portion 112 (see FIGS. 2B and 2C ). As shown in FIG. 2A , the pair of first protruding portions 112A are disposed on the lower edge side of the side wall portion 111. In the lead frame 110, the side wall portion 111 extends along the second end surface E2 of the exterior body 120 from between the pair of first protruding portions 112A toward the terminal surface Sc of the cathode portion 15. The solid electrolytic capacitor 100 configured as described above can increase the contact area between the second external electrode 140 and the lead frame 110. This allows for more optimal electrical connection between the lead frame 110 and the second external electrode 140.

[0035] In solid electrolytic capacitor 100 according to the first embodiment, lead frame 110 extends in first direction D1 along the lower end surface of cathode portion 15 and further includes bottom plate portion 113 connected to side wall portion 111 and the pair of first protrusions 112A. When lead frame 110 is configured as described above, bottom plate portion 113 can adequately support multiple capacitor elements 10 from below.

[0036] In the solid electrolytic capacitor 100 according to the first embodiment, the bottom plate portion 113 of the lead frame 110 is connected to the lower end surface of the cathode portion 15 of the capacitor element 10 by a fourth conductive paste layer (not shown). With the above configuration, the lower end surface of the capacitor element 10 can also be electrically connected to the lead frame 110. That is, the bottom plate portion 113 of the lead frame 110 can be electrically connected so as to contact the lower end surface of the cathode portion 15. In FIG. 2A , the boundary between the bottom plate portion 113 and the first protruding portion 112A is indicated by a dashed line L1. This also applies to the side cross-sectional views ( FIGS. 2E and 2H ) of the solid electrolytic capacitors according to the second and third embodiments described below.

[0037] As described above, when lead frame 110 includes bottom plate 113 in addition to side wall 111 and first protruding portion 112A, the angle formed between bottom plate 113 and side wall 111 is preferably an obtuse angle in which side wall 111 is inclined toward second end face E2 of exterior body 120. The obtuse angle as described above makes it easier to place cathode 15 of capacitor element 10 on lead frame 110.

[0038] In the solid electrolytic capacitor 100 according to the first embodiment, the thickness of the side wall portion 111 and the first protruding portion 112A in the lead frame 110 is preferably 0.08 mm or more and 0.30 mm or less. By making the side wall portion 111 and the first protruding portion 112A have such a thickness, deformation of the side wall portion 111 and the first protruding portion 112A in the thickness direction can be suppressed when the multiple capacitor elements 10 and the lead frame 110 are resin-sealed to obtain an outer casing. It is also preferable that the second protruding portion 112B, which will be described later, has a thickness within the above range.

[0039] In the solid electrolytic capacitor 100 according to the first embodiment, a notch S is preferably formed in the lead frame 110 between the pair of first protrusions 112A and the sidewalls 111 (see FIG. 2B ). Here, the sidewalls 111 of the lead frame 110 are typically formed by bending a portion of a flat plate (e.g., a metal plate). Therefore, if the regions corresponding to the sidewalls 111 and the regions corresponding to the pair of first protrusions 112A are in contact with each other in the flat plate, the regions corresponding to the sidewalls 111 are likely to be obstructed by the regions corresponding to the first protrusions 112A when the flat plate is bent. However, by forming the notch S, the regions corresponding to the sidewalls 111 and the regions corresponding to the first protrusions 112A can be kept out of contact with each other in the flat plate. This makes the regions corresponding to the sidewalls 111 less likely to be obstructed by the regions corresponding to the first protrusions 112A when the flat plate is bent. That is, the area corresponding to the side wall portion 111 can be easily bent to any desired position.

[0040] In the solid electrolytic capacitor 100 according to the first embodiment, it is preferable that the corners of the bottom plate portion 113 of the lead frame 110 opposite the side wall portion 111 are chamfered (see FIG. 2D ). Such chamfering can prevent the corners of the bottom plate portion 113 from deforming. This provides the bottom plate portion 113 with excellent shape stability. The chamfering may be R-chamfering or C-chamfering. From the viewpoint of further preventing deformation of the corners, it is preferable that the chamfering be R-chamfering.

[0041] Second Embodiment Next, a solid electrolytic capacitor 100 according to a second embodiment of the present disclosure will be described with reference to Figures 2E to 2G. The solid electrolytic capacitor 100 according to the second embodiment is the same as the solid electrolytic capacitor 100 according to the first embodiment except for the configuration of the lead frame 110. Therefore, the configuration of the lead frame 110 of the solid electrolytic capacitor 100 according to the second embodiment will be described below.

[0042] In the solid electrolytic capacitor 100 according to the second embodiment, as shown in FIGS. 2E to 2G , the lead frame 110 includes a pair of first protrusions 112A spaced apart from each other, as well as a pair of second protrusions 112B on the side wall 111 that is disposed between the pair of first protrusions 112A and extends along the second end face E2 of the exterior package 120. That is, in the solid electrolytic capacitor 100 according to the second embodiment, the lead frame 110 includes a pair of first protrusions 112A and a pair of second protrusions 112B that are disposed between the pair of first protrusions 112A. The pair of second protrusions 112B extend from both side edges of the side wall 111 toward the second end face E2 of the exterior package 120. In the solid electrolytic capacitor 100 according to the second embodiment, the lead frame 110 is electrically connected to the second external electrode 140 via the pair of second protrusions 112B in addition to the pair of first protrusions 112A. In other words, at the second end surface E2 of the outer casing 120, the tip surface Ss of the first protrusion 112A of the lead frame 110 and the tip surface St of the second protrusion 112B are exposed, and are electrically connected to the second external electrode 140 by the tip surface Ss and the tip surface St.

[0043] By configuring the lead frame 110 as described above, it is possible to increase the contact area between the lead frame 110 and the second external electrode 140. This makes it possible to reduce the equivalent series resistance (ESR) of the solid electrolytic capacitor 100.

[0044] 2E shows an example in which a pair of second protrusions 112B are arranged on the upper end sides of the side wall portion 111 in the height direction, but the arrangement of the pair of second protrusions 112B on the side wall portion 111 is not limited to this. The pair of second protrusions 112B may be arranged at any position in the height direction of the side wall portion 111. For example, the pair of second protrusions 112B may be arranged on the lower end sides of the side wall portion 111 in the height direction, or may be arranged on the center side of the side wall portion 111 in the height direction. The pair of second protrusions 112B can be formed, for example, by bending both side edge sides of the side wall portion 111 so as to align with the extension direction of the pair of first protrusions 112A.

[0045] 2H to 2J, a solid electrolytic capacitor 100 according to a third embodiment of the present disclosure will be described. The solid electrolytic capacitor 100 according to the third embodiment is the same as the solid electrolytic capacitor 100 according to the first embodiment except for the configuration of the lead frame 110. Therefore, the configuration of the lead frame 110 of the solid electrolytic capacitor 100 according to the third embodiment will be described below.

[0046] 2H to 2J , in the solid electrolytic capacitor 100 according to the third embodiment, the lead frame 110 includes, in addition to a pair of first protrusions 112A spaced apart from each other, a second protrusion 112B also on the side wall 111 that is disposed between the pair of first protrusions 112A and extends along the second end face E2 of the exterior package 120. That is, in the solid electrolytic capacitor 100 according to the third embodiment, the lead frame 110 includes, in addition to the pair of first protrusions 112A, a second protrusion 112B that is disposed between the pair of first protrusions 112A. The second protrusion 112B extends from the upper edge of the side wall 111 toward the second end face E2 of the exterior package 120. In the solid electrolytic capacitor 100 according to the third embodiment, the lead frame 110 is electrically connected to the second external electrode 140 via one second protruding portion 112B in addition to the pair of first protruding portions 112A. In other words, at the second end surface E2 of the exterior body 120, the protruding end surfaces Ss of the pair of first protruding portions 112A and the protruding end surface St of the one second protruding portion 112B of the lead frame 110 are exposed, and are electrically connected to the second external electrode 140 by the protruding end surfaces Ss and St.

[0047] Similarly to the second embodiment, the lead frame 110 configured as described above can increase the contact area between the lead frame 110 and the second external electrode 140. This can reduce the equivalent series resistance (ESR) of the solid electrolytic capacitor 100.

[0048] One second protruding portion 112B can be formed, for example, by bending the upper edge side of the side wall portion 111 along the extension direction of the pair of first protruding portions 112A.

[0049] 2K to 2M, a solid electrolytic capacitor 100 according to a fourth embodiment of the present disclosure will be described. The solid electrolytic capacitor 100 according to the fourth embodiment is the same as the solid electrolytic capacitor 100 according to the first embodiment except for the configuration of the lead frame 110. Therefore, the configuration of the lead frame 110 of the solid electrolytic capacitor 100 according to the fourth embodiment will be described below.

[0050] In the solid electrolytic capacitor 100 according to the fourth embodiment, as shown in FIGS. 2K to 2M, the lead frame 110 includes a pair of spaced-apart sidewalls 111 and a single first protrusion 112A extending from between the pair of sidewalls 111 toward the second end face E2 of the exterior package 120. Therefore, in the cross-sectional side view of the solid electrolytic capacitor 100 according to the fourth embodiment, the sidewalls 111 appear closer to the page than the first protrusion 112A in part A of FIG. 2K. Note that in FIG. 2K, the boundary between the sidewalls 111 and the bottom plate 113 is indicated by a dashed line L2. As shown in FIG. 2M, the first protrusion 112A has a protruding end face Ss exposed at the second end face E2 of the exterior package 120, and is electrically connected to the second external electrode 140 via the protruding end face Ss. The single first protrusion 112A is disposed on the lower edge of the sidewalls 111.

[0051] By configuring the lead frame 110 as described above, the area of ​​the protruding end surface Ss of the first protruding portion 112A can be increased compared to when a pair of first protruding portions 112A is provided. This makes it easier to establish contact between the first protruding portion 112A and the second external electrode 140. Furthermore, by providing a pair of sidewall portions 111, current collection can be more efficient and the equivalent series resistance can be reduced. Furthermore, each of the multiple capacitor elements 10 stacked in the height direction can be sufficiently supported from the cathode portion 15 side. This sufficiently prevents each of the multiple capacitor elements 10 from shifting position when stacked.

[0052] [Method for manufacturing a solid electrolytic capacitor] A method for manufacturing a solid electrolytic capacitor according to the present disclosure is a method for manufacturing a solid electrolytic capacitor comprising: at least one capacitor element having an anode portion and a cathode portion extending from the anode portion in a first direction; a lead frame electrically connected to the cathode portion; an exterior body sealing the at least one capacitor element and the lead frame; a first external electrode electrically connected to the anode portion at a first end face on one side of the exterior body in the first direction; and a second external electrode electrically connected to the lead frame at a second end face on the other side of the exterior body in the first direction, wherein the lead frame has a side wall portion extending along the second end face of the exterior body and facing an end face of the cathode portion in the first direction, and a protrusion portion extending toward the second end face of the exterior body, intersecting the side wall portion, and exposed at the second end face, wherein the anode portion has a protruding end face exposed at the first end face of the exterior body and is electrically connected to the first external electrode via the protruding end face, and the lead frame is electrically connected to the second external electrode via the protruding portion.

[0053] a second step of forming a cathode portion so as to cover at least a portion of the dielectric layer to obtain a laminate in which the anode portion, the dielectric layer, and the cathode portion are stacked in this order; a third step of disposing the laminate on a lead frame having sidewall portions and protruding portions extending in a direction intersecting the sidewall portions, with the sidewall portions of the lead frame and an end surface of the cathode portion electrically connected to each other, and sealing the lead frame and the laminate to obtain a sealed body; a fourth step of exposing a protruding end surface of the anode portion from a first end surface of the sealed body and exposing a protruding end surface of the protruding portion of the lead frame from a second end surface of the sealed body; and a fifth step of disposing a first external electrode so as to be electrically connected to the protruding end surface of the anode portion exposed from the first end surface of the sealed body, and disposing a second external electrode so as to be electrically connected to the protruding end surface of the protruding portion of the lead frame exposed from the second end surface of the sealed body.

[0054] In the first step, the dielectric layer covering at least a portion of the anode part can be formed by various known methods. The dielectric layer can be formed by oxidizing the valve metal contained in the anode part by chemical conversion treatment or the like. For example, the dielectric layer may be formed by immersing the anode part in a chemical conversion solution and applying a voltage. The anode part may have a porous part formed therein, which includes a plurality of pores opening from the outer surface toward the center. When a porous part is formed in the anode part, the dielectric layer is preferably formed so as to cover at least a portion of the outer surface of the anode part and at least a portion of the inner surface of each of the plurality of pores.

[0055] In the second step, the cathode covering at least a portion of the dielectric layer can be formed by various known methods. The solid electrolyte layer in the cathode can be formed by immersing the anode on which the dielectric layer has been formed in a conductive polymer solution containing a conductive polymer to deposit the conductive polymer solution on the dielectric layer, and then drying the conductive polymer solution deposited on the dielectric layer. When a porous portion is formed in the anode, the anode after depositing the conductive polymer solution on the dielectric layer is preferably exposed to a pressure higher or lower than the pressure P1 applied when the cathode was immersed in the conductive polymer solution. By exposing the anode to a pressure higher than P1, the conductive polymer solution can be forced into the multiple pores at high pressure, while by exposing the anode to a pressure lower than P1, the conductive polymer solution can be drawn into the multiple pores at low pressure. That is, the pressure difference from the pressure P1 allows a portion of the conductive polymer solution deposited on the dielectric layer formed on the outer surface of the anode to move into the multiple pores.

[0056] The cathode extraction layer in the cathode portion can be obtained, for example, by applying a carbon dispersion liquid containing dispersed carbon to cover at least a portion of the solid electrolyte layer, drying the liquid to form a carbon layer, and then applying a composition containing metal particles (e.g., silver particles) and a resin component (binder resin) to cover at least a portion of the carbon layer, and drying the composition to form a conductor layer. Note that, when the binder resin is a thermosetting resin, the binder resin can be thermally cured by the heating.

[0057] In the third step, a lead frame having sidewall portions and protruding portions extending in a direction intersecting the sidewall portions can be obtained by processing a metal plate into a predetermined shape. For example, it can be obtained by performing the bending process described in the first to fourth embodiments. In addition to the sidewall portions and protruding portions, the lead frame preferably further includes a bottom plate portion connected to the sidewall portions and the protruding portions. By including the bottom plate portion in the lead frame, it is possible to sufficiently support from the underside a laminate in which an anode portion, a dielectric layer, and a cathode portion are stacked in this order. The bottom plate portion preferably extends in the same direction as the extending direction of the protruding portions. In other words, the bottom plate portion preferably extends in a direction intersecting the sidewall portions.

[0058] The lead frame preferably has a first protruding portion as the protruding portion. As described above, the first protruding portion is a protruding portion arranged on the lower edge side of the side wall portion. A pair of first protruding portions may be arranged spaced apart from each other on the lower edge side of the side wall portion (as in the configuration of the first embodiment described above), or a single first protruding portion may be arranged (as in the configuration of the fourth embodiment described above). When the lead frame has a pair of first protruding portions, it is preferable that a second protruding portion be arranged between the pair of first protruding portions in order to reduce the equivalent series resistance (ESR) of the solid electrolytic capacitor. A pair of second protruding portions may be arranged between the pair of first protruding portions (as in the configuration of the second embodiment described above), or a single second protruding portion may be arranged (as in the configuration of the third embodiment described above).

[0059] The side wall portion of the lead frame and the end surface of the cathode portion can be electrically connected, for example, by interposing a conductive paste layer therebetween. The lead frame and the laminate are sealed, for example, by using a sealing resin or the like to embed the entire lead frame and the laminate. When the sealing resin is a thermosetting resin, it is preferable that the sealing resin be thermally cured after embedding the lead frame and the laminate. For sealing with the sealing resin, conventionally known techniques such as transfer molding or compression molding can be applied.

[0060] In the fourth step, the first and second end faces of the sealing body are cut to a predetermined size, for example, by blade dicing or using an ultrasonic cutter, so that the protruding end faces of the anode portion and the protruding end faces of the lead frame are exposed. A cold spray treatment may be performed to form a coating on the first and second end faces of the sealing body after cutting. This prevents natural oxidation of the protruding end faces of the anode portion and the protruding end faces of the protruding portion exposed by cutting. Metal particles such as copper (Cu), aluminum (Al), titanium (Ti), silver (Ag), nickel (Ni), zinc (Zn), tin (Sn), molybdenum (Mo), iron (Fe), tantalum (Ta), niobium (Nb), silicon (Si), and chromium (Cr) can be used for the cold spray treatment.

[0061] In the fifth step, the first external electrode can be obtained by applying a conductive paste containing conductive particles (e.g., silver particles) to the first end face of the cut sealing body, drying the paste to form a conductive paste layer, and then plating a metal (e.g., nickel) on the conductive paste layer to form a metal plating layer. The second external electrode can be obtained in the same manner as above, by forming a conductive paste layer and a metal plating layer in this order on the second end face of the cut sealing body. The first external electrode obtained as described above is electrically connected to the protruding end face of the anode portion, and the second external electrode obtained as described above is electrically connected to the protruding end face of the protruding portion of the lead frame.

[0062] As described above, by carrying out the first to fifth steps, a solid electrolytic capacitor according to an embodiment of the present disclosure can be obtained.

[0063] In the method for manufacturing a solid electrolytic capacitor according to an embodiment of the present disclosure, a single metal plate on which multiple lead frames are formed may be used. Specifically, a single metal plate on which multiple lead frames are formed so as to be aligned in the length and width directions may be used. By using a single metal plate on which multiple lead frames are formed, multiple sealed bodies can be obtained at once by sealing the multiple lead frames and multiple laminates together on the single metal plate in the third step. The multiple sealed bodies can be individually cut out from the single metal plate by dicing or the like.

[0064] Although the present specification has described an example in which the solid electrolytic capacitor 100 includes a plurality of capacitor elements 10 as an embodiment, the solid electrolytic capacitor 100 may include only one capacitor element 10. Furthermore, the present specification has described an example in which the protruding end face of the anode portion 11 is exposed and electrically connected to the first external electrode 130 in the solid electrolytic capacitor 100 as an embodiment, but the electrical connection between the anode portion 11 and the first external electrode 130 is not limited to this. The anode portion 11 and the first external electrode 130 may be electrically connected via a lead frame.

[0065] (Additional Note) The above description discloses the following technology: (Technology 1) A solid electrolytic capacitor comprising: at least one capacitor element having an anode portion and a cathode portion extending from the anode portion in a first direction, a lead frame electrically connected to the cathode portion, a housing sealing the at least one capacitor element and the lead frame, a first external electrode electrically connected to the anode portion at a first end face on one side of the housing in the first direction, and a second external electrode electrically connected to the lead frame at a second end face on the other side of the housing in the first direction, wherein the lead frame has: a side wall portion extending along the second end face of the housing and facing an end face of the cathode portion in the first direction, and an overhang portion extending toward the second end face of the housing, intersecting the side wall portion, and exposed at the second end face, and the lead frame is electrically connected to the second external electrode via the overhang portion. (Technology 2) The solid electrolytic capacitor according to Technology 1, wherein the anode portion has a protruding end surface exposed on a first end surface of the exterior body and is electrically connected to the first external electrode via the protruding end surface. (Technology 3) The solid electrolytic capacitor according to Technology 1 or 2, wherein the lead frame includes, as the protruding portion, a pair of first protruding portions spaced apart from each other, the pair of first protruding portions being arranged on lower edge sides of the side wall portion, and the side wall portion extending along the second end surface of the exterior body from between the pair of first protruding portions toward the end surface of the cathode portion. (Technology 4) The solid electrolytic capacitor according to Technology 3, wherein the lead frame further includes, as the protruding portion, a pair of second protruding portions being arranged between the pair of first protruding portions, and the pair of second protruding portions respectively contacting both side edge sides of the side wall portion. (Technology 5) The solid electrolytic capacitor according to Technology 3, wherein the lead frame further includes one second protruding portion disposed between the pair of first protruding portions, and the one second protruding portion is in contact with an upper edge side of the side wall portion.(Technology 6) The solid electrolytic capacitor according to Technology 1 or 2, wherein the lead frame includes a pair of side wall portions spaced apart from each other, and the protruding portion includes one first protruding portion extending from between the pair of side wall portions toward the second end surface of the exterior body, and the one first protruding portion is disposed on the lower edge side of the side wall portions. (Technology 7) The solid electrolytic capacitor according to Technology 3, wherein the lead frame further includes a bottom plate portion extending in the first direction along a lower end surface of the cathode portion and connected to the side wall portions and the pair of first protruding portions, and the bottom plate portion contacts and is electrically connected to the lower end surface of the cathode portion. (Technology 8) The solid electrolytic capacitor according to any one of Technology 1 to 7, wherein the side wall portion contacts and is electrically connected to an end surface of the cathode portion. (Technology 9) The solid electrolytic capacitor according to Technology 7 or 8, wherein an angle formed between the bottom plate portion and the side wall portion is an obtuse angle such that the side wall portion is inclined toward the second end surface of the exterior body. (Technology 10) The solid electrolytic capacitor according to any one of Technologies 1 to 9, wherein in the lead frame, the side wall portions and the protruding portions have thicknesses of 0.08 mm or more and 0.30 mm or less. (Technology 11) The solid electrolytic capacitor according to any one of Technologies 3 to 5, wherein in the lead frame, notches are formed between the pair of first protruding portions and the side wall portions. (Technology 12) The solid electrolytic capacitor according to Technology 7, wherein in the lead frame, corners of the bottom plate portion opposite the side wall portions are chamfered.

[0066] While the present invention has been described with respect to presently preferred embodiments, such disclosure should not be interpreted as limiting. Various variations and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. It is therefore intended that the appended claims be interpreted to cover all variations and modifications that do not depart from the true spirit and scope of the invention.

[0067] The solid electrolytic capacitor according to the present disclosure can be used in applications where it is required to suppress a decrease in capacitance.

[0068] 10: capacitor element, 11: anode portion, 12: dielectric layer, 13: solid electrolyte layer, 14: cathode lead layer, 15: cathode portion, 100: solid electrolytic capacitor, 110: lead frame, 111: side wall portion, 112: extension portion, 112A: first extension portion, 112B: second extension portion, 113: bottom plate portion, 120: exterior body, 130: first external electrode, 140: second external electrode, C: coated portion, D1: first direction, E1: first end face, E2: second end face, NC: uncoated portion, S: notch, Sa: tip face, Sc: terminal face, Ss: tip face, St: tip face

Claims

1. A solid electrolytic capacitor comprising: at least one capacitor element having an anode portion and a cathode portion extending from the anode portion in a first direction; a lead frame electrically connected to the cathode portion; an exterior housing sealing the at least one capacitor element and the lead frame; a first external electrode electrically connected to the anode portion at a first end face on one side of the exterior housing in the first direction; and a second external electrode electrically connected to the lead frame at a second end face on the other side of the exterior housing in the first direction, wherein the lead frame has: a side wall portion extending along the second end face of the exterior housing and facing an end face of the cathode portion in the first direction; and a protrusion portion extending toward the second end face of the exterior housing, intersecting the side wall portion, and exposed at the second end face, wherein the lead frame is electrically connected to the second external electrode via the protrusion portion.

2. The solid electrolytic capacitor according to claim 1, wherein the anode portion has a pointed end surface exposed at a first end surface of the outer casing, and is electrically connected to the first external electrode via the pointed end surface.

3. The solid electrolytic capacitor according to claim 1 or 2, wherein the lead frame has a pair of first protrusions spaced apart from each other as the protrusions, the pair of first protrusions being arranged on the lower edge sides of the side wall portions, and the side wall portions extending from between the pair of first protrusions toward the end face of the cathode portion along the second end face of the exterior body.

4. The solid electrolytic capacitor according to claim 3, wherein the lead frame further comprises a pair of second protruding portions disposed between the pair of first protruding portions, and the pair of second protruding portions respectively contact both side edge sides of the side wall portion.

5. The solid electrolytic capacitor according to claim 3, wherein the lead frame further comprises one second protruding portion disposed between the pair of first protruding portions, and the one second protruding portion is in contact with the upper edge of the side wall portion.

6. The solid electrolytic capacitor according to claim 1 or 2, wherein the lead frame has a pair of side wall portions spaced apart from each other, and the protrusion includes one first protrusion extending from between the pair of side wall portions toward the second end surface of the exterior body, and the one first protrusion is arranged on the lower edge side of the side wall portion.

7. The solid electrolytic capacitor according to claim 3, wherein the lead frame further comprises a bottom plate portion extending in the first direction along a lower end surface of the cathode portion and connected to the side wall portion and the pair of first protrusions, and the bottom plate portion abuts and is electrically connected to the lower end surface of the cathode portion.

8. The solid electrolytic capacitor according to claim 1 or 2, wherein the side wall portion is in contact with and electrically connected to an end face of the cathode portion.

9. The solid electrolytic capacitor according to claim 7, wherein the angle formed between the bottom plate and the side wall is an obtuse angle such that the side wall is inclined toward the second end surface of the exterior body.

10. The solid electrolytic capacitor according to claim 1 or 2, wherein the thickness of the side wall portion and the protruding portion of the lead frame is 0.08 mm or more and 0.30 mm or less.

11. The solid electrolytic capacitor according to claim 3, wherein the lead frame has notches formed between the pair of first protrusions and the side wall portions.

12. The solid electrolytic capacitor according to claim 7, wherein the corner of the bottom plate portion of the lead frame opposite the side wall portion is chamfered.

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