Solid electrolytic capacitor and method for manufacturing the same

Abstract

To provide a manufacturing method of a solid electrolytic capacitor, capable of performing a resistance welding without a problem even if a copper is used as a base material of a positive electrode terminal, and a solid electrolytic capacitor manufactured by the manufacturing method.SOLUTION: A solid electrolytic capacitor 100 comprises: a capacitor element 200; a positive electrode terminal 400; and a negative electrode terminal 500. The capacitor element 200 comprises: a positive electrode body 210; and a positive electrode lead wire 300 extended from the positive electrode body 210 in a horizontal direction. Both of a lower surface 324 of a thin film part 320 and a lower surface 314 of a thick film part 310 are provided on the same surface. On the other hand, an upper surface 322 of the thin film part 320 is positioned lower than an upper surface 312 of the thick film part 310 in a vertical direction orthogonal to the horizontal direction. In a state where one end 410 of the positive electrode terminal 400 is positioned on the thin film part 320 of the positive electrode lead wire 300 and an overlapping part 450 of the positive electrode terminal 400 is overlapped with the thick film part 310 of the positive electrode lead wire 300, the positive electrode terminal 400 is bonded to the positive electrode lead wire 300.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a solid electrolytic capacitor including a capacitor element and an anode terminal, and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 discloses a solid electrolytic capacitor 900 of this type. As shown in FIG. 10, the solid electrolytic capacitor 900 of Patent Document 1 includes a capacitor element 910, an outer resin 920, an anode terminal 930, and a cathode terminal 940. The capacitor element 910 includes an anode body 912, a solid electrolyte layer 914, a conductor layer 916, and an anode lead wire 918. The anode body 912 is made of a valve action metal. A dielectric layer 913 is formed on the surface of the anode body 912, and the solid electrolyte layer 914 is formed on the dielectric layer 913. The conductor layer 916 is formed on the solid electrolyte layer 914. The anode lead wire 918 is formed by pulling out one end of the anode body 912. Specifically, the anode lead wire 918 is partially embedded in the anode body 912 and extends horizontally from the anode body 912. The outer resin 920 covers the capacitor element 910. The anode terminal 930 is connected to the anode lead wire 918. The cathode terminal 940 is connected to the conductor layer 916.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] At the time of filing Patent Document 1, it was mainstream to use iron-nickel as the base material of the anode terminal. On the other hand, due to the desire to further reduce the ESR, in recent years, copper has been increasingly used as the base material of the anode terminal. Here, since copper has a lower melting point than iron-nickel, the anode terminal is likely to melt during resistance welding. Also, generally, when a metal melts, its resistance increases. Therefore, in the configuration of Patent Document 1, during resistance welding, the resistance becomes too high due to the melting of copper at the joint between the anode terminal and the anode lead wire, which may cause abnormal heat generation.

[0005] An object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor that can be resistance-welded without problems even when copper is used as the base material of the anode terminal, and a solid electrolytic capacitor manufactured by the manufacturing method.

Means for Solving the Problems

[0006] As a first method for manufacturing a solid electrolytic capacitor, the present invention forming a capacitor element including an anode body made of a valve-acting metal, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer formed on the dielectric layer, a conductor layer formed on the solid electrolyte layer, and an anode lead wire partially embedded in the anode body and extending horizontally from the anode body, wherein the anode lead wire has a thick portion and a thin portion located closer to the anode body side than the thick portion in the horizontal direction, the lower surface of the thin portion and the lower surface of the thick portion are on the same plane, while in the vertical direction orthogonal to the horizontal direction, the upper surface of the thin portion is located below the upper surface of the thick portion; partially arranging the anode terminal on the anode lead wire such that one end of the anode terminal is positioned above the thin portion and an overlapping portion located on the other end side of the one end of the anode terminal overlaps with the thick portion; Both the upper electrode and the lower electrode are arranged to occupy a region corresponding to the thick portion of the anode lead wire in the horizontal direction and partially occupy a region corresponding to the thin portion of the anode lead wire, and the one end of the anode terminal and the thin portion of the anode lead wire are sandwiched between the upper electrode and the lower electrode, and the overlapping portion of the anode terminal and the thick portion of the anode lead wire are sandwiched, and a current is passed while applying pressure in the vertical direction to perform resistance welding to join the anode terminal and the anode lead wire. Provided is a method for manufacturing a solid electrolytic capacitor including the above.

[0007] Further, the present invention provides, as a first solid electrolytic capacitor, a solid electrolytic capacitor including a capacitor element, an anode terminal, and a cathode terminal, wherein the capacitor element includes an anode body made of a valve action metal, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer formed on the dielectric layer, a conductor layer formed on the solid electrolyte layer, and an anode lead wire partially embedded in the anode body and extending horizontally from the anode body. The anode lead wire has a thick portion and a thin portion located closer to the anode body side than the thick portion in the horizontal direction. The lower surface of the thin portion and the lower surface of the thick portion are on the same plane, while in the vertical direction orthogonal to the horizontal direction, the upper surface of the thin portion is located below the upper surface of the thick portion. The anode terminal has at least one end, the other end, and an overlapping portion located on the other end side from the one end. The anode terminal is joined to the anode lead wire in a state where the one end of the anode terminal is located on the thin portion and the overlapping portion of the anode terminal overlaps with the thick portion. The upper surface of the one end of the anode terminal and the upper surface of the overlapping portion of the anode terminal are on the same plane. Provided is a solid electrolytic capacitor.

[0008] Further, the present invention provides a first solid electrolytic capacitor as a second solid electrolytic capacitor, wherein when the size of the thick portion in the horizontal direction is St and the size of the joint portion between the anode terminal and the anode lead wire in the horizontal direction is Sc, St / Sc ≦ 0.5 is satisfied. A solid electrolytic capacitor is provided.

[0009] Further, the present invention provides a third solid electrolytic capacitor as a first or second solid electrolytic capacitor, wherein the anode lead wire has a connecting portion connecting the thin portion and the thick portion, the connecting portion has an intersecting surface that connects the upper surface of the thin portion and the upper surface of the thick portion and intersects the vertical direction. A solid electrolytic capacitor is provided.

[0010] Further, the present invention provides a fourth solid electrolytic capacitor as any one of the first to third solid electrolytic capacitors, wherein the anode lead wire is made of tantalum, the base material of the anode terminal is copper. A solid electrolytic capacitor is provided.

Advantages of the Invention

[0011] According to the present invention, as welding progresses, the anode lead wire is pressed against the melted anode terminal, and the anode terminal and the anode lead wire come into contact not only in the thick portion but also in the thin portion. That is, as welding progresses, the contact area between the anode terminal and the anode lead wire increases. Thereby, it is possible to avoid the resistance at the joint portion from becoming too high and prevent the temperature from becoming too high.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0013] (First Embodiment) As shown in FIG. 1, the solid electrolytic capacitor 100 according to the first embodiment of the present invention includes a capacitor element 200, an anode terminal 400, a cathode terminal 500, a conductive resin 580, and an exterior insulating member 590. The manufacturing method of the solid electrolytic capacitor 100 will be described later.

[0014] As shown in FIG. 1, the capacitor element 200 of the present embodiment includes an anode body 210, a dielectric layer 220, a cathode layer 240, and an anode lead wire 300.

[0015] Referring to FIG. 1, the anode body 210 of the present embodiment is made of a valve - acting metal. Specifically, the anode body 210 is a porous sintered body made of sintered valve - acting metal powder. That is, the anode body 210 of the present embodiment has sintered valve - acting metal powder and a large number of pores. Here, the valve - acting metal powder is tantalum powder.

[0016] Referring to FIG. 1, the dielectric layer 220 of the present embodiment is an anodic oxide film, that is, made of tantalum oxide. The dielectric layer 220 is formed on the surface of the anode body 210. Specifically, the dielectric layer 220 is formed on a part of the anode body 210 and on the anode lead wire 300.

[0017] As shown in FIG. 1, the cathode layer 240 of the present embodiment includes a solid electrolyte layer 230 and a conductor layer 570. The solid electrolyte layer 230 is formed on the dielectric layer 220, and the conductor layer 570 is formed on the solid electrolyte layer 230. However, the present invention is not limited thereto. The cathode layer 240 may have other structures as long as it includes the solid electrolyte layer 230. The cathode layer 240 is formed on the dielectric layer 220 so as to wrap the entire anode body 210. In other words, the dielectric layer 220 is located between the anode body 210 and the solid electrolyte layer 230.

[0018] The solid electrolyte layer 230 of the present embodiment is made of polyethylene dioxythiophene. That is, the solid electrolyte layer 230 of the present embodiment is made of a conductive polymer. The solid electrolyte layer 230 is formed by repeatedly immersing the anode body 210 on which the dielectric layer 220 is formed in a conductive polymer solution, taking it out, and drying it. The conductive polymer solution is a solution containing an aqueous solution of ethylenedioxythiophene, an oxidizing agent, and a dopant. As the oxidizing agent, various substances such as iron salts of inorganic acids or organic acids can be used. Also, as the dopant, various substances such as polystyrene sulfonic acid can be used.

[0019] The conductor layer 570 of this embodiment is a laminate of a carbon layer and a conductive paste layer. However, the present invention is not limited to this. The conductor layer 570 may have a configuration other than the laminate of the carbon layer and the conductive paste layer. In this embodiment, the conductor layer 570 is formed on the solid electrolyte layer 230. The carbon layer is formed by immersing the anode body 210 on which the solid electrolyte layer 230 is formed in a solution containing carbon black, a graphite filler, and a binder, taking it out, and drying it. Further, the conductive paste layer is formed by applying a silver paste on the surface of the carbon layer and drying it.

[0020] Referring to FIG. 1, the anode lead wire 300 of this embodiment is made of tantalum. The anode lead wire 300 is partially embedded in the anode body 210 and extends horizontally from the anode body 210. In this embodiment, the horizontal direction is the X direction. Also, the horizontal direction is the front-rear direction. Here, the front is defined as the +X direction and the rear is defined as the -X direction. The rear portion of the anode lead wire 300 is embedded in the anode body 210. The anode lead wire 300 extends forward in the front-rear direction from the anode body 210. As shown in FIG. 2, the anode lead wire 300 has a thick portion 310 and a thin portion 320.

[0021] As shown in FIG. 2, the thick portion 310 of this embodiment is located at the end of the anode lead wire 300 in the horizontal direction. More specifically, the thick portion 310 is located at the front end of the anode lead wire 300 in the front-rear direction. In the vertical direction perpendicular to the horizontal direction, the size of the thick portion 310 is larger than the size of the thin portion 320. The vertical direction in this embodiment is the Z direction. Here, the upper side is defined as the +Z direction and the lower side is defined as the -Z direction. The thick portion 310 has an upper surface 312 and a lower surface 314 in the vertical direction.

[0022] As can be understood from FIGS. 1 and 2, the thin portion 320 of the present embodiment is located closer to the anode body 210 side than the thick portion 310 in the horizontal direction. The thin portion 320 has an upper surface 322 and a lower surface 324 in the vertical direction. The lower surface 324 of the thin portion 320 and the lower surface 314 of the thick portion 310 are on the same plane. In the vertical direction orthogonal to the horizontal direction, the upper surface 322 of the thin portion 320 is located below the upper surface 312 of the thick portion 310.

[0023] As shown in FIG. 2, the anode lead wire 300 has a connecting portion 330. Note that the present invention is not limited to this, and the anode lead wire 300 may not have the connecting portion 330. That is, the thin portion 320 and the thick portion 310 may be directly connected so that a step is formed between the thin portion 320 and the thick portion 310.

[0024] As shown in FIG. 2, the connecting portion 330 of the present embodiment is located between the thin portion 320 and the thick portion 310 in the horizontal direction. The connecting portion 330 is located behind the thick portion 310 in the front-rear direction. The connecting portion 330 is located in front of the thin portion 320 in the front-rear direction. The connecting portion 330 connects the thin portion 320 and the thick portion 310. The connecting portion 330 has an intersecting surface 332 and a lower surface 334. The intersecting surface 332 intersects the vertical direction. The intersecting surface 332 intersects the horizontal direction, that is, the front-rear direction. Note that the present invention is not limited to this, and the intersecting surface 332 up and down may not intersect the direction. Also, the intersecting surface 332 may be a plane or a curved surface. In addition, the intersecting surface 332 may have a step or unevenness. The intersecting surface 332 connects the upper surface 322 of the thin portion 320 and the upper surface 312 of the thick portion 310. The lower surface 334 of the connecting portion 330, the lower surface 324 of the thin portion 320, and the lower surface 314 of the thick portion 310 are on the same plane.

[0025] Referring to FIGS. 1 and 2, the base material of the anode terminal 400 of the present embodiment is copper. That is, the anode terminal 400 is formed by applying Ni plating to a copper base material. The anode terminal 400 has one end 410, the other end 420, an overlapping portion 450 located on the other end 420 side from one end 410, and an additional overlapping portion 460 located between one end 410 and the overlapping portion 450. Note that the present invention is not limited thereto, and the anode terminal 400 may have at least one end 410, the other end 420, and an overlapping portion 450 located on the other end 420 side from one end 410. That is, the anode terminal 400 may not have the additional overlapping portion 460.

[0026] As shown in FIGS. 1 and 2, each of one end 410 and the other end 420 of the present embodiment is a free end. One end 410 has an upper surface 412 and a lower surface 414 in the vertical direction.

[0027] As shown in FIG. 2, the overlapping portion 450 of the present embodiment is located in front of one end 410 in the front-rear direction. The overlapping portion 450 is located in front of the additional overlapping portion 460 in the front-rear direction. The overlapping portion 450 has an upper surface 452 and a lower surface 454 in the vertical direction.

[0028] As shown in FIG. 2, the additional overlapping portion 460 of the present embodiment is located between one end 410 and the overlapping portion 450 in the horizontal direction. The additional overlapping portion 460 is located in front of one end 410 in the front-rear direction. The additional overlapping portion 460 has an upper surface 462 and an inclined surface 464 in the vertical direction.

[0029] As shown in FIG. 2, one end 410 of the anode terminal 400 is located on the thin portion 320, and the overlapping portion 450 of the anode terminal 400 overlaps with the thick portion 310. In this state, the anode terminal 400 is joined to the anode lead wire 300. More specifically, one end 410 of the anode terminal 400 is located on the thin portion 320, the additional overlapping portion 460 of the anode terminal 400 is located on the connecting portion 330, and the overlapping portion 450 of the anode terminal 400 overlaps with the thick portion 310. In this state, the anode terminal 400 is joined to the anode lead wire 300. The upper surface 412 of one end 410 of the anode terminal 400 and the upper surface 452 of the overlapping portion 450 of the anode terminal 400 are on the same plane. More specifically, the upper surface 412 of one end 410 of the anode terminal 400, the upper surface 462 of the additional overlapping portion 460 of the anode terminal 400, and the upper surface 452 of the overlapping portion 450 of the anode terminal 400 are on the same plane. The upper surface 312 of the thick portion 310 is in contact with the lower surface 454 of the overlapping portion 450 in the vertical direction. The intersecting surface 332 of the connecting portion 330 is in contact with the inclined surface 464 of the additional overlapping portion 460 in the vertical direction. The upper surface 322 of the thin portion 320 is in contact with the lower surface 414 of one end 410 in the vertical direction.

[0030] Referring to FIG. 2, when the size of the thick portion 310 in the horizontal direction is St and the size of the joint portion between the anode terminal 400 and the anode lead wire 300 in the horizontal direction is Sc, St / Sc≤0.5 is satisfied. Thereby, it becomes easy to specify the melted portion of the anode terminal 400 welded to the anode lead wire 300.

[0031] Referring to FIG. 1, the cathode terminal 500 of the present embodiment is formed by forming a solder plating on a substrate made of 42 alloy. However, the cathode terminal 500 may be made of other metals.

[0032] Referring to FIG. 1, the conductive resin 580 according to the present embodiment is made of a silver paste. The cathode terminal 500 is adhered onto the conductor layer 570 of the capacitor element 200 using the conductive resin 580. Note that other conductive adhesives may be used instead of the conductive resin 580.

[0033] Referring to FIG. 1, the exterior insulating member 590 of the present embodiment is formed to include a part of the anode terminal 400 and a part of the cathode terminal 500 and wrap the entire capacitor element 200. The exterior insulating member 590 of the present embodiment is made of an epoxy resin and is formed by injection molding using a mold of a predetermined shape and curing it. However, the exterior insulating member 590 may be made of other insulating materials. In this way, the capacitor element 200 is sealed from the outside by the exterior insulating member 590.

[0034] The solid electrolytic capacitor 100 of the present embodiment is manufactured as follows.

[0035] As shown in FIG. 3, the solid electrolytic capacitor 100 of the present embodiment is manufactured through step 1 (formation step), step 2 (arrangement step), and step 3 (bonding step). In other words, the manufacturing method of the solid electrolytic capacitor 100 includes a formation step, an arrangement step, and a bonding step.

[0036] First, referring to FIGS. 1 and 2, a forming process for forming the capacitor element 200 of the present embodiment is performed. Specifically, in this forming process, an anode body 210 made of a valve-acting metal, a dielectric layer 220 formed on the surface of the anode body 210, a solid electrolyte layer 230 formed on the dielectric layer 220, a conductor layer 570 formed on the solid electrolyte layer 230, and an anode lead wire 300 partially embedded in the anode body 210 and extending horizontally from the anode body 210 are provided. The capacitor element 200 includes an anode lead wire 300 having a thick portion 310 and a thin portion 320 located closer to the anode body 210 than the thick portion 310 in the horizontal direction. The lower surface 324 of the thin portion 320 and the lower surface 314 of the thick portion 310 are on the same plane, while the upper surface 322 of the thin portion 320 is located below the upper surface 312 of the thick portion 310 in the vertical direction perpendicular to the horizontal direction. Here, in the capacitor element 200, the anode lead wire 300 has a connecting portion 330 that connects the thin portion 320 and the thick portion 310 and has an intersecting surface 332 that intersects the vertical direction. The thick portion 310, the thin portion 320, and the connecting portion 330 of the anode lead wire 300 are roll-formed by a mold. Note that the method for forming the capacitor element 200 including the anode lead wire 300 is not particularly limited and may be formed by a known method.

[0037] Next, after performing the forming process, referring to FIG. 4, an arranging process is performed. Specifically, in this arranging process, one end 410 of the anode terminal 400 is positioned above the thin portion 320, and the anode terminal 400 is partially arranged on the anode lead wire 300 such that an overlapping portion 450 located on the other end 420 side from the one end 410 of the anode terminal 400 overlaps with the thick portion 310. More specifically, one end 410 of the anode terminal 400 is positioned above the thin portion 320, and an additional overlapping portion 460 of the anode terminal 400 is positioned on the connecting portion 330, and the anode terminal 400 is partially arranged on the anode lead wire 300 such that the overlapping portion 450 located on the other end 420 side from the one end 410 of the anode terminal 400 overlaps with the thick portion 310.

[0038] Next, after performing the placement process, refer to FIGS. 4 and 5 and perform the joining process. Specifically, in this joining process, both the upper electrode 700 and the lower electrode 800 are arranged to occupy the region A1 corresponding to the thick portion 310 of the anode lead wire 300 and partially occupy the region A2 corresponding to the thin portion 320 of the anode lead wire 300 in the horizontal direction. Then, one end 410 of the anode terminal 400 and the thin portion 320 of the anode lead wire 300 are sandwiched between the upper electrode 700 and the lower electrode 800, and the overlapping portion 450 of the anode terminal 400 and the thick portion 310 of the anode lead wire 300 are sandwiched, and a current is passed while applying pressure in the vertical direction to perform resistance welding to join the anode terminal 400 and the anode lead wire 300.

[0039] That is, in this joining process, first, both the upper electrode 700 and the lower electrode 800 are arranged to occupy the region A1 corresponding to the thick portion 310 of the anode lead wire 300 and partially occupy the region A2 corresponding to the thin portion 320 of the anode lead wire 300 in the horizontal direction. More specifically, both the upper electrode 700 and the lower electrode 800 are arranged to occupy the region A3 corresponding to the thick portion 310 and the connecting portion 330 of the anode lead wire 300 and partially occupy the region A2 corresponding to the thin portion 320 of the anode lead wire 300 in the horizontal direction. Next, one end 410 of the anode terminal 400 and the thin portion 320 of the anode lead wire 300 are sandwiched between the upper electrode 700 and the lower electrode 800, and the overlapping portion 450 of the anode terminal 400 and the thick portion 310 of the anode lead wire 300 are sandwiched. More specifically, one end 410 of the anode terminal 400 and the thin portion 320 of the anode lead wire 300 are sandwiched between the upper electrode 700 and the lower electrode 800, the additional overlapping portion 460 of the anode terminal 400 and the connecting portion 330 of the anode lead wire 300 are sandwiched between the upper electrode 700 and the lower electrode 800, and the overlapping portion 450 of the anode terminal 400 and the thick portion 310 of the anode lead wire 300 are sandwiched between the upper electrode 700 and the lower electrode 800. At this time, the upper electrode 700 is in contact with the upper surface 412 (see FIG. 2) of the one end 410, the upper surface 462 (see FIG. 2) of the additional overlapping portion 460, and the upper surface 452 (see FIG. 2) of the overlapping portion 450 in the vertical direction. Also, at this time, the lower electrode 800 is in contact with the lower surface 324 (see FIG. 2) of the thin portion 320, the lower surface 334 (see FIG. 2) of the connecting portion 330, and the lower surface 314 (see FIG. 2) of the thick portion 310 in the vertical direction. Finally, in this sandwiched state, while applying pressure so that the upper electrode 700 and the lower electrode 800 approach each other in the vertical direction, a current is passed through the upper electrode 700 and the lower electrode 800 to join the anode terminal 400 and the anode lead wire 300 by resistance welding.

[0040] Referring to FIG. 2, in the solid electrolytic capacitor 100 manufactured through this bonding process, the size St in the horizontal direction of the thick portion 310 and the size Sc in the horizontal direction of the bonding portion between the anode terminal 400 and the anode lead wire 300 satisfy St / Sc≤0.5. Thereby, since the contact area between the anode terminal 400 and the anode lead wire 300 at the start of the resistance welding between the anode terminal 400 and the anode lead wire 300 does not become too large, the weldability between the anode terminal 400 and the anode lead wire 300 is enhanced.

[0041] According to the manufacturing method of the present embodiment, in the above bonding process, as the welding between the anode terminal 400 and the anode lead wire 300 progresses, the anode lead wire 300 is pressed against the melted anode terminal 400, and the anode terminal 400 and the anode lead wire 300 come into contact not only in the thick portion 310 but also in the thin portion 320. That is, as the welding between the anode terminal 400 and the anode lead wire 300 progresses, the contact area between the anode terminal 400 and the anode lead wire 300 becomes larger. Thereby, it is possible to avoid the resistance in the joint portion between the anode terminal 400 and the anode lead wire 300 from becoming too high, and it is possible to prevent the anode terminal 400 from becoming too hot. From these facts, in the manufacturing method of the present embodiment, during the resistance welding between the anode terminal 400 and the anode lead wire 300, it is suppressed that a part of the anode terminal 400 melts and diffuses to the region on the anode body 210 side.

[0042] In particular, according to the manufacturing method of the present embodiment, in the above bonding step, as the welding between the anode terminal 400 and the anode lead wire 300 progresses, the anode lead wire 300 is pressed against the melted anode terminal 400, and the anode terminal 400 and the anode lead wire 300 also come into contact at the intersection surface 332. That is, as the welding between the anode terminal 400 and the anode lead wire 300 progresses, the contact area between the anode terminal 400 and the anode lead wire 300 gradually expands. Thereby, it is possible to further avoid the resistance at the joint between the anode terminal 400 and the anode lead wire 300 from becoming too high, and it is possible to further prevent the anode terminal 400 from becoming too hot. From these facts, in the manufacturing method of the present embodiment, during the resistance welding between the anode terminal 400 and the anode lead wire 300, it is particularly suppressed that a part of the anode terminal 400 melts and diffuses to the region on the anode body 210 side.

[0043] Assume a case where a spherical melt is generated due to the melting of the anode terminal 400 in the above bonding step. In the manufacturing method of the present embodiment, since the welding between the anode terminal 400 and the anode lead wire 300 starts from the thick portion 310 away from the anode body 210, even if the above-described spherical melt is generated, it will be generated at a location away from the anode body 210. Thereby, in the solid electrolytic capacitor 100 manufactured by the manufacturing method of the present embodiment, the path length of the migration of metal ions that can occur from the spherical melt to the cathode layer 240 side under high temperature and high humidity is long, and the occurrence of insulation failure is suppressed.

[0044] After the above steps, through the connection of the cathode terminal 500 to the capacitor element 200 and the sealing of the capacitor element 200 by the exterior insulating member 590, the solid electrolytic capacitor 100 of the present embodiment is manufactured.

[0045] (Second Embodiment) As shown in FIG. 6, the solid electrolytic capacitor 100X according to the second embodiment of the present invention includes a capacitor element 200X, an anode terminal 400X, a cathode terminal 500, a conductive resin 580, and an exterior insulating member 590. Here, the configurations other than the capacitor element 200X and the anode terminal 400X are the same as those in the first embodiment. Therefore, the same reference numerals are used for the same configurations as in the first embodiment, and detailed descriptions thereof are omitted. Also, the orientation and direction in the present embodiment use the same expressions as those in the first embodiment hereinafter.

[0046] As shown in FIG. 6, the capacitor element 200X of the present embodiment includes an anode body 210, a dielectric layer 220, a cathode layer 240, and an anode lead wire 300X. Here, since the configurations other than the anode lead wire 300X are the same as those in the first embodiment, detailed descriptions thereof are omitted.

[0047] Referring to FIGS. 6 and 7, the anode lead wire 300X of the present embodiment is made of tantalum. The anode lead wire 300X is partially embedded in the anode body 210 and extends horizontally from the anode body 210. The rear portion of the anode lead wire 300X is embedded in the anode body 210. The anode lead wire 300X extends forward in the front-rear direction from the anode body 210. The anode lead wire 300X has a thick portion 310 and a thin portion 320. Different from the anode lead wire 300 in the first embodiment, the anode lead wire 300X of the present embodiment does not have a connecting portion 330. That is, in the anode lead wire 300X of the present embodiment, the thin portion 320 and the thick portion 310 are directly connected so that a step is formed between the thin portion 320 and the thick portion 310.

[0048] Referring to FIGS. 6 and 7, the base material of the anode terminal 400X of the present embodiment is copper. That is, the anode terminal 400X is formed by nickel-plating a copper base material. The anode terminal 400X has one end 410, the other end 420, and an overlapping portion 450 located on the other end 420 side from the one end 410. That is, unlike the anode terminal 400 of the first embodiment, the anode terminal 400X of the present embodiment does not have an additional overlapping portion 460.

[0049] As shown in FIGS. 6 and 7, each of the one end 410 and the other end 420 of the present embodiment is a free end. The one end 410 has an upper surface 412 and a lower surface 414 in the vertical direction.

[0050] As shown in FIG. 7, the overlapping portion 450 of the present embodiment is located in front of the one end 410 in the front-rear direction. The overlapping portion 450 has an upper surface 452 and a lower surface 454 in the vertical direction.

[0051] As shown in FIG. 7, with one end 410 of the anode terminal 400X located on the thin portion 320 and the overlapping portion 450 of the anode terminal 400X overlapping with the thick portion 310, the anode terminal 400X is joined to the anode lead wire 300X. The upper surface 412 of the one end 410 of the anode terminal 400X and the upper surface 452 of the overlapping portion 450 of the anode terminal 400X are on the same plane. The upper surface 312 of the thick portion 310 is in contact with the lower surface 454 of the overlapping portion 450 in the vertical direction. The upper surface 322 of the thin portion 320 is in contact with the lower surface 414 of the one end 410 in the vertical direction.

[0052] Referring to FIG. 7, when the size of the thick portion 310 in the horizontal direction is St and the size of the joining portion of the anode terminal 400X and the anode lead wire 300X in the horizontal direction is Sc, St / Sc ≤ 0.5 is satisfied. Thereby, it becomes easy to specify the melting portion of the anode terminal 400X welded to the anode lead wire 300X.

[0053] The solid electrolytic capacitor 100X of the present embodiment is manufactured as follows.

[0054] The solid electrolytic capacitor 100X of this embodiment is manufactured through step1 (formation process), step2 (arrangement process), and step3 (bonding process) in the same manner as the solid electrolytic capacitor 100 of the above-described first embodiment. In other words, the manufacturing method of the solid electrolytic capacitor 100X includes a formation process, an arrangement process, and a bonding process.

[0055] First, referring to FIGS. 6 and 7, a formation process for forming the capacitor element 200X of this embodiment is performed. Specifically, in this formation process, a capacitor element 200X including an anode body 210 made of a valve-acting metal, a dielectric layer 220 formed on the surface of the anode body 210, a solid electrolyte layer 230 formed on the dielectric layer 220, a conductor layer 570 formed on the solid electrolyte layer 230, and an anode lead wire 300X partially embedded in the anode body 210 and extending horizontally from the anode body 210 is formed. The anode lead wire 300X has a thick portion 310 and a thin portion 320 located closer to the anode body 210 than the thick portion 310 in the horizontal direction. While the lower surface 324 of the thin portion 320 and the lower surface 314 of the thick portion 310 are on the same plane, the upper surface 322 of the thin portion 320 is located below the upper surface 312 of the thick portion 310 in the vertical direction perpendicular to the horizontal direction. Here, the anode lead wire 300X of the capacitor element 200X has the thin portion 320 and the thick portion 310 directly connected so that a step is formed between the thin portion 320 and the thick portion 310. The thick portion 310 and the thin portion 320 of the anode lead wire 300X are roll-formed by a mold. Note that the formation method of the capacitor element 200X including the anode lead wire 300X is not particularly limited and may be formed by a known method.

[0056] Next, after the formation process is performed, referring to FIG. 8, an arrangement process is performed. Specifically, in this arrangement process, one end 410 of the anode terminal 400X is positioned above the thin portion 320, and the anode terminal 400X is partially arranged on the anode lead wire 300X such that an overlapping portion 450 located on the other end 420 side from one end 410 of the anode terminal 400X overlaps with the thick portion 310.

[0057] Next, after performing the placement process, refer to FIGS. 8 and 9 and perform the joining process. Specifically, in this joining process, both the upper electrode 700 and the lower electrode 800 are arranged to occupy the region AX1 corresponding to the thick portion 310 of the anode lead wire 300X and partially occupy the region AX2 corresponding to the thin portion 320 of the anode lead wire 300X in the horizontal direction. Then, one end 410 of the anode terminal 400X and the thin portion 320 of the anode lead wire 300X are sandwiched between the upper electrode 700 and the lower electrode 800, and the overlapping portion 450 of the anode terminal 400X and the thick portion 310 of the anode lead wire 300X are sandwiched, and a current is passed while applying pressure in the vertical direction to perform resistance welding to join the anode terminal 400X and the anode lead wire 300X.

[0058] That is, in this joining process, first, both the upper electrode 700 and the lower electrode 800 are arranged to occupy the region AX1 corresponding to the thick portion 310 of the anode lead wire 300X and partially occupy the region AX2 corresponding to the thin portion 320 of the anode lead wire 300X in the horizontal direction. Next, one end 410 of the anode terminal 400X and the thin portion 320 of the anode lead wire 300X are sandwiched between the upper electrode 700 and the lower electrode 800, and the overlapping portion 450 of the anode terminal 400X and the thick portion 310 of the anode lead wire 300X are sandwiched. At this time, the upper electrode 700 is in contact with the upper surface 412 of the one end 410 (see FIG. 7) and the upper surface 452 of the overlapping portion 450 (see FIG. 7) in the vertical direction. Also, at this time, the lower electrode 800 is in contact with the lower surface 324 of the thin portion 320 (see FIG. 7) and the lower surface 314 of the thick portion 310 (see FIG. 7) in the vertical direction. Finally, in this sandwiched state, a current is passed through the upper electrode 700 and the lower electrode 800 while applying pressure so that the upper electrode 700 and the lower electrode 800 approach each other in the vertical direction, and the anode terminal 400X and the anode lead wire 300X are joined by resistance welding.

[0059] Referring to FIG. 7, in the solid electrolytic capacitor 100X manufactured through this bonding process, the size St in the horizontal direction of the thick portion 310 and the size Sc in the horizontal direction of the bonding portion between the anode terminal 400X and the anode lead wire 300X satisfy St / Sc≦0.5. Thereby, since the contact area between the anode terminal 400X and the anode lead wire 300X at the start of the resistance welding of the anode terminal 400X and the anode lead wire 300X does not become too large, the weldability between the anode terminal 400X and the anode lead wire 300X is enhanced.

[0060] According to the manufacturing method of the present embodiment, in the above bonding process, as the welding between the anode terminal 400X and the anode lead wire 300X progresses, the anode lead wire 300X is pressed against the melted anode terminal 400X, and the anode terminal 400X and the anode lead wire 300X come into contact not only in the thick portion 310 but also in the thin portion 320. That is, as the welding between the anode terminal 400X and the anode lead wire 300X progresses, the contact area between the anode terminal 400X and the anode lead wire 300X becomes larger. Thereby, it is possible to avoid the resistance in the joint portion between the anode terminal 400X and the anode lead wire 300X from becoming too high, and it is possible to prevent the anode terminal 400X from becoming too hot. From these facts, also in the manufacturing method of the present embodiment, during the resistance welding between the anode terminal 400X and the anode lead wire 300X, it is suppressed that a part of the anode terminal 400X melts and diffuses to the region on the anode body 210 side.

[0061] Assume a case where spherical melt is generated due to the melting of the anode terminal 400X in the above bonding process. In the manufacturing method of the present embodiment, since the welding between the anode terminal 400X and the anode lead wire 300X starts from the thick portion 310 away from the anode body 210, even if the above-mentioned spherical melt is generated, it will be generated at a location away from the anode body 210. Thereby, also in the solid electrolytic capacitor 100X manufactured by the manufacturing method of the present embodiment, the migration path length of metal ions that can occur from the spherical melt to the cathode layer 240 side under high temperature and high humidity is long, and the occurrence of insulation failure is suppressed.

[0062] After the above steps, through the connection of the cathode terminal 500 to the capacitor element 200X and the sealing of the capacitor element 200X by the exterior insulating member 590, the solid electrolytic capacitor 100X of the present embodiment is manufactured.

[0063] As described above, the present invention has been specifically described with reference to the embodiments. However, the present invention is not limited thereto, and various modifications and changes are possible.

Explanation of Reference Numerals

[0064] 100, 100X Solid electrolytic capacitor 200, 200X Capacitor element 210 Anode body 220 Dielectric layer 230 Solid electrolyte layer 240 Cathode layer 300, 300X Anode lead wire 310 Thick portion 312 Upper surface 314 Lower surface 320 Thin portion 322 Upper surface 324 Lower surface 330 Connecting portion 332 Intersection surface 334 Lower surface 400, 400X Anode terminal 410 One end 412 Upper surface 414 Lower surface 420 The other end 450 Overlapping portion 452 Upper surface 454 Lower surface 460 Additional overlapping portion 462 Upper surface 464 Inclined surface 500 Cathode terminal 570 Conductor layer 580 Conductive resin 590 Exterior insulating member 700 Upper electrode 800 Lower electrode A1, AX1 Region A2, AX2 area A3 area St size Sc size

Claims

1. A capacitor element comprising an anode body made of valve-acting metal, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer formed on the dielectric layer, a conductor layer formed on the solid electrolyte layer, and an anode lead wire partially embedded in the anode body and extending horizontally from the anode body, wherein the anode lead wire has a thick portion, a thin portion located closer to the anode body side than the thick portion in the horizontal direction, and a connecting portion connecting the thin portion and the thick portion, the lower surface of the thin portion and the lower surface of the thick portion are on the same plane, while in the vertical direction orthogonal to the horizontal direction, the upper surface of the thin portion is located below the upper surface of the thick portion, and the connecting portion is an intersection surface connecting the upper surface of the thin portion and the upper surface of the thick portion and intersecting the vertical direction, the step of forming a capacitor element; The step of disposing the anode terminal partially on the anode lead wire such that one end of the anode terminal is positioned above the thin portion and an overlapping portion located on the other end side of the one end of the anode terminal overlaps with the thick portion; The step of disposing both the upper electrode and the lower electrode so as to occupy a region corresponding to the thick portion of the anode lead wire in the horizontal direction and partially occupy a region corresponding to the thin portion of the anode lead wire, sandwiching the one end of the anode terminal and the thin portion of the anode lead wire between the upper electrode and the lower electrode, sandwiching the overlapping portion of the anode terminal and the thick portion of the anode lead wire, and flowing a current while applying pressure in the vertical direction to perform resistance welding to join the anode terminal and the anode lead wire; A method for manufacturing a solid electrolytic capacitor comprising the above steps.

2. A solid electrolytic capacitor comprising a capacitor element, an anode terminal, and a cathode terminal, wherein the capacitor element comprises an anode body made of valve-acting metal, a dielectric layer formed on the surface of the anode body, a solid electrolyte layer formed on the dielectric layer, a conductor layer formed on the solid electrolyte layer, and an anode lead wire partially embedded in the anode body and extending horizontally from the anode body, the anode lead wire has a thick portion and a thin portion located closer to the anode body side than the thick portion in the horizontal direction. The lower surface of the thin portion and the lower surface of the thick portion are on the same plane. On the other hand, in the vertical direction perpendicular to the horizontal direction, the upper surface of the thin portion is located below the upper surface of the thick portion. The anode terminal has at least one end, the other end, and an overlapping portion located on the other end side from the one end. With the one end of the anode terminal located on the thin portion and the overlapping portion of the anode terminal overlapping the thick portion, the anode terminal is joined to the anode lead wire. The upper surface of the one end of the anode terminal and the upper surface of the overlapping portion of the anode terminal are on the same plane. The anode lead wire has a connecting portion that connects the thin portion and the thick portion. The connecting portion is an intersecting surface that connects the upper surface of the thin portion and the upper surface of the thick portion and has an intersecting surface that intersects the vertical direction. Solid electrolytic capacitor.

3. The solid electrolytic capacitor according to claim 2, When the size of the thick portion in the horizontal direction is St and the size of the joining portion of the anode terminal and the anode lead wire in the horizontal direction is Sc, St / Sc ≤ 0.5 is satisfied. Solid electrolytic capacitor.

4. The solid electrolytic capacitor according to claim 2 or claim 3, The anode lead wire is made of tantalum. The base material of the anode terminal is copper. Solid electrolytic capacitor.

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