Solid electrolytic capacitor and method of manufacturing solid electrolytic capacitor

Abstract

To provide a new manufacturing method in which a positive electrode lead is joined to a positive electrode lead frame by laser welding, the method being suitable for manufacturing a solid electrolytic capacitor with excellent characteristic.SOLUTION: The present invention provides a method of manufacturing a solid electrolytic capacitor 10 comprising: a positive electrode body 20; a positive electrode lead 30; and a positive electrode lead frame 40. The positive electrode lead 30 extends from a front surface 22 of the positive electrode body 20 to a front direction. The positive electrode lead frame 40 includes a standing portion 44. The manufacturing method comprises: an opposing step in which a predetermined region in a rear surface 444 of the standing portion 44 is opposed to a front end 32 of the positive electrode lead 30; and a welding step in which the predetermined region of the standing portion 44 is irradiated with a laser beam LL toward from an irradiation position RP positioned to an upper direction and a rear direction of the standing portion 44, and the front end 32 of the standing portion 44 and the positive electrode lead 30 are welded.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a solid electrolytic capacitor including an anode body, an anode lead, and an anode lead frame.

Background Art

[0002] This type of solid electrolytic capacitor is disclosed in Patent Document 1.

[0003] Patent Document 1 discloses a solid electrolytic capacitor including an anode body (anode body), an anode wire (anode lead), and an anode terminal portion (anode lead frame). An organic electrolyte layer is provided at the front end of the anode body. The organic electrolyte layer is covered by a light reflection layer. The anode lead frame is located in front of the light reflection layer. The anode lead passes through the light reflection layer and protrudes forward. The anode lead is laser welded to the anode lead frame. According to Patent Document 1, since the light reflection layer is provided, damage to the organic electrolyte layer due to reflection of laser light during laser welding is prevented, and thus deterioration of the characteristics of the solid electrolytic capacitor is prevented.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] There is a need for a new technique for laser welding an anode lead and an anode lead frame to each other while preventing deterioration of the characteristics of a solid electrolytic capacitor.

[0006] Therefore, an object of the present invention is to provide a new manufacturing method for laser-welding an anode lead to an anode lead frame, which is a manufacturing method suitable for manufacturing a solid electrolytic capacitor with excellent characteristics. Another object of the present invention is to provide a solid electrolytic capacitor in which an anode lead is laser-welded to an anode lead frame, which is a solid electrolytic capacitor with excellent characteristics.

Means for Solving the Problems

[0007] As a first manufacturing method, the present invention is a manufacturing method of a solid electrolytic capacitor including an anode body, an anode lead, and an anode lead frame, wherein the anode lead extends forward from the front surface in the front-rear direction of the anode body, the anode lead frame has a rising portion, an opposing step of opposing a predetermined region on the rear surface of the rising portion and the front end of the anode lead, and a welding step of irradiating laser light from an irradiation position located above and behind the rising portion in the up-down direction orthogonal to the front-rear direction toward the predetermined region of the rising portion to weld the rising portion and the front end of the anode lead is provided. A manufacturing method is provided.

[0008] As a second manufacturing method, the present invention is the first manufacturing method, wherein in the opposing step, when a gap is formed between the rear surface of the rising portion and the front end of the anode lead, the gap widens upward, and the angle formed by the rear surface of the rising portion and the front end of the anode lead is 13° or less A manufacturing method is provided.

[0009] As a third manufacturing method, the present invention is the second manufacturing method, wherein in the opposing step, the angle formed by the front end of the anode lead and the lower end of the anode lead is 80° or more Provide a manufacturing method.

[0010] As a fourth manufacturing method, the present invention is a first manufacturing method, In the facing step, the angle formed by the virtual line extending forward from the lower end of the rising portion and the rear surface of the rising portion is 93° or less. Provide a manufacturing method.

[0011] As a fifth manufacturing method, the present invention is a first manufacturing method, In the facing step, the angle formed by the front end of the anode lead and the lower end of the anode lead is 90° or less. Provide a manufacturing method.

[0012] As a sixth manufacturing method, the present invention is any one of the first to fifth manufacturing methods, The size of the minor axis of the condensing point of the laser beam in the predetermined region is 0.01 mm or more and 0.05 mm or less. Provide a manufacturing method.

[0013] As a first solid electrolytic capacitor, the present invention is A solid electrolytic capacitor including an anode body, an anode lead, and an anode lead frame, The anode lead extends forward from the front surface in the front-rear direction of the anode body, The anode lead frame has a rising portion, The front end of the anode lead is welded to a predetermined region on the rear surface of the rising portion, Laser marks are formed on at least one of the front end of the anode lead and the predetermined region of the rising portion. Provide a solid electrolytic capacitor.

[0014] As a second solid electrolytic capacitor, the present invention is a first solid electrolytic capacitor, In the lateral direction orthogonal to the front-rear direction, the rising portion has a size larger than the front end of the anode lead. Two notches are formed in the starting portion. The two notches are respectively formed at both ends of the starting portion in the lateral direction. Each of the notches is recessed inward of the starting portion in the lateral direction. Provide a solid electrolytic capacitor.

[0015] The present invention is a first solid electrolytic capacitor as a third solid electrolytic capacitor, A recess is formed on the front surface of the starting portion. The recess is located at a position corresponding to the predetermined region in a vertical plane perpendicular to the front-rear direction and is recessed rearward. Provide a solid electrolytic capacitor.

[0016] The present invention is a third solid electrolytic capacitor as a fourth solid electrolytic capacitor, The recess has an elliptical shape. The recess has a first size in the lateral direction perpendicular to the front-rear direction and has a second size in the vertical direction perpendicular to both the front-rear direction and the lateral direction. The second size is larger than the first size. Provide a solid electrolytic capacitor.

[0017] The present invention is a fourth solid electrolytic capacitor as a fifth solid electrolytic capacitor, The second size is twice or more the first size. Provide a solid electrolytic capacitor.

[0018] The present invention is a solid electrolytic capacitor according to any one of the first to fifth solid electrolytic capacitors as a sixth solid electrolytic capacitor, The solid electrolytic capacitor includes an exterior resin. The anode body and the anode lead are located inside the exterior resin. The distance between the front surface of the exterior resin and the front surface of the anode body is 0.3 mm or more and 0.5 mm or less. To provide a solid electrolytic capacitor.

[0019] The present invention is, as a seventh solid electrolytic capacitor, any one of the first to fifth solid electrolytic capacitors, comprising a cathode layer and a cathode lead frame, wherein the cathode layer is electrically connected to the cathode lead frame via a conductive adhesive, and the conductive adhesive is a conductive metal paste To provide a solid electrolytic capacitor.

Advantages of the Invention

[0020] According to the present invention, the front end of the anode lead is opposed to the rear surface of the rising portion and welded. According to this manufacturing method, when the manufactured solid electrolytic capacitor is covered with an exterior resin, the space occupied by the anode lead frame can be reduced, and the front surface of the anode body can be brought closer to the front surface of the exterior resin. As a result, the volume efficiency of the anode body in the solid electrolytic capacitor including the exterior resin can be increased, and thus a solid electrolytic capacitor with excellent characteristics can be obtained. Further, when welding the rising portion and the front end of the anode lead, the laser beam is irradiated from an irradiation position located above and behind the rising portion. According to this irradiation method, welding can be surely performed with relatively small irradiation energy, and deterioration of the characteristics of the solid electrolytic capacitor can be prevented.

[0021] Summarizing the above description, according to the present invention, there is provided a new manufacturing method of laser-welding an anode lead to an anode lead frame, which is a manufacturing method suitable for manufacturing a solid electrolytic capacitor with excellent characteristics. Further, the solid electrolytic capacitor manufactured by the above manufacturing method has excellent characteristics. That is, according to the present invention, there is provided a solid electrolytic capacitor in which an anode lead is laser-welded to an anode lead frame, and the solid electrolytic capacitor has excellent characteristics.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0023] Referring to FIGS. 1 and 2, a solid electrolytic capacitor 10 according to an embodiment of the present invention includes a main body portion 12 having capacitance, an exterior resin 18 made of an insulator, an anode lead frame 40 made of a conductor, and a cathode lead frame 60 made of a conductor. The solid electrolytic capacitor 10 of the present embodiment includes the above-described members. However, the present invention is not limited thereto. For example, the solid electrolytic capacitor 10 may further include another member in addition to the above-described members.

[0024] The solid electrolytic capacitor 10 of the present embodiment has a rectangular flat plate shape parallel to the horizontal plane (XY plane). In particular, the solid electrolytic capacitor 10 of the present embodiment has a small size of about 0.6 mm in the vertical direction orthogonal to the horizontal plane. In other words, the thickness of the solid electrolytic capacitor 10 is thin. More specifically, the thickness of the solid electrolytic capacitor 10 is smaller than half the length of the short side of the solid electrolytic capacitor 10 in the horizontal plane. However, the present invention is not limited to the small and thin solid electrolytic capacitor 10 and is applicable to solid electrolytic capacitors having various shapes and sizes.

[0025] The vertical direction of the present embodiment is the Z direction. In the present embodiment, "upward" is the +Z direction and "downward" is the -Z direction. Terms related to positions such as the horizontal plane and the vertical direction do not indicate an absolute positional relationship with respect to the ground, but merely indicate a relative positional relationship in the drawing. For example, in the present embodiment, a plane in which the main surface of a circuit board (not shown) on which the solid electrolytic capacitor 10 is mounted extends is defined as the horizontal plane.

[0026] The main body 12 of this embodiment generally has a rectangular flat plate shape parallel to the horizontal plane (XY plane). The anode lead frame 40 and the cathode lead frame 60 are fixed to the main body 12. The main body 12 is generally located above the anode lead frame 40 and the cathode lead frame 60. The exterior resin 18 is molded from resin so as to embed the main body 12, the anode lead frame 40, and the cathode lead frame 60 therein. That is, the main body 12, the anode lead frame 40, and the cathode lead frame 60 are embedded inside the exterior resin 18. However, each of the anode lead frame 40 and the cathode lead frame 60 is partially exposed outside the exterior resin 18.

[0027] Referring to FIG. 2, the exposed portion of the anode lead frame 40 exposed from the exterior resin 18 functions as the anode terminal 41, and the exposed portion of the cathode lead frame 60 exposed from the exterior resin 18 functions as the cathode terminal 61. When using the solid electrolytic capacitor 10, the anode terminal 41 and the cathode terminal 61 are respectively soldered to a conductive pattern (not shown) formed on the upper surface of a circuit board (not shown).

[0028] The main body 12 includes an anode body 20, an anode lead 30 made of a metal such as tantalum, and a cathode layer 50. That is, the solid electrolytic capacitor 10 includes an anode body 20, an anode lead 30, and a cathode layer 50. The anode body 20 of this embodiment includes a plurality of layers including an anode (not shown) made of a valve metal such as tantalum and a dielectric layer (not shown) covering the anode. The cathode layer 50 of this embodiment includes a plurality of layers including a solid electrolyte layer (not shown) covering the dielectric layer and a surface layer made of a conductor such as silver paste. The anode body 20, the anode lead 30, and the cathode layer 50 are located inside the exterior resin 18. Specifically, the anode body 20, the anode lead 30, and the cathode layer 50 are completely embedded inside the exterior resin 18.

[0029] The cathode layer 50 covers the entire anode body 20 except for the front surface 22 of the anode body 20 in the front-rear direction orthogonal to the vertical direction. The front-rear direction in the present embodiment is the X direction. In the present embodiment, "front" is the +X direction, and "rear" is the -X direction.

[0030] The anode lead 30 of the present embodiment has a cylindrical shape extending along the front-rear direction. The rear portion of the anode lead 30 is embedded inside the anode body 20, and the front portion of the anode lead 30 protrudes forward from the front surface 22 of the anode body 20. That is, the anode lead 30 extends forward from the front surface 22 of the anode body 20 in the front-rear direction.

[0031] The anode lead 30 has a front end 32 which is a cut surface in the manufacturing process of the anode lead 30. As will be described later, the front end 32 is welded to the anode lead frame 40. The front end 32 before welding is a plane parallel to the vertical plane (YZ plane) orthogonal to the front-rear direction and has a small circular shape. The diameter of the front end 32 is smaller than the size of the main body portion 12 in the vertical direction. For example, the size of the main body portion 12 in the vertical direction is about 0.3 mm, and the diameter of the front end 32 is about 0.15 mm.

[0032] The main body portion 12 of the present embodiment has the above-described structure and can be manufactured, for example, by a conventional manufacturing method as disclosed in Patent Document 1. However, as long as the anode body 20 for holding the anode lead 30 is provided in the solid electrolytic capacitor 10, the structure and manufacturing method of the main body portion 12 in the present invention are not particularly limited. For example, the anode lead 30 may have a polygonal prism shape extending along the front-rear direction. The front end 32 of the anode lead 30 before welding may be a plane obliquely intersecting the front-rear direction.

[0033] Referring to FIG. 5 in combination with FIGS. 2 and 3, each of the anode lead frame 40 and the cathode lead frame 60 of the present embodiment is formed by bending a single metal piece cut out from a metal plate into a predetermined shape. That is, each of the anode lead frame 40 and the cathode lead frame 60 is a single bent metal plate.

[0034] Each of the anode lead frame 40 and the cathode lead frame 60 in the present embodiment is formed of a relatively easily machinable metal such as iron or copper. Therefore, the melting point of each of the anode lead frame 40 and the cathode lead frame 60 is considerably lower than the melting point of the anode lead 30 made of tantalum. However, the material, structure, and manufacturing method of each of the anode lead frame 40 and the cathode lead frame 60 in the present invention are not particularly limited. Also, the cathode lead frame 60 may be provided as necessary.

[0035] Hereinafter, the anode lead frame 40 of the present embodiment will be described in more detail.

[0036] Referring to FIG. 3 in combination with FIG. 2, the anode lead frame 40 of the present embodiment has a base portion 42 and a rising portion 44. The size of the base portion 42 in the lateral direction is slightly smaller than the size of the main body portion 12 in the lateral direction. The size of the rising portion 44 in the lateral direction is larger than the diameter of the front end 32 of the anode lead 30. The anode lead frame 40 has only the above-described portions. However, the present invention is not limited thereto. For example, the anode lead frame 40 may further have another portion in addition to the above-described portions.

[0037] Referring to FIG. 3, the base portion 42 of the present embodiment extends along the horizontal plane (XY plane). The base portion 42 has a main portion 422 and two leg portions 424. The main portion 422 has a rectangular flat plate shape parallel to the horizontal plane. The front edge of the main portion 422 extends along the lateral direction that is orthogonal to both the vertical direction and the front-rear direction. The lateral direction in the present embodiment is the Y direction. The two leg portions 424 are respectively connected to both sides in the lateral direction of the front edge of the main portion 422. Each of the leg portions 424 extends forward from the front edge of the main portion 422.

[0038] The base portion 42 of the anode lead frame 40 of the present embodiment has the above-described structure. However, the present invention is not limited thereto, and the structure of the base portion 42 can be deformed as necessary. Also, the base portion 42 may be provided as necessary.

[0039] The starting portion 44 of the present embodiment extends along the vertical plane (YZ plane) as a whole. Specifically, the starting portion 44 is connected to the middle portion in the lateral direction of the front edge of the main portion 422. The starting portion 44 extends forward from the front edge of the main portion 422, then bends in an arc shape, and extends upward. The starting portion 44 has a front surface 442 and a rear surface 444. Each of the front surface 442 and the rear surface 444 of the present embodiment is a flat surface without unevenness.

[0040] The starting portion 44 of the anode lead frame 40 of the present embodiment has the above-described structure. However, the present invention is not limited thereto, and the structure of the starting portion 44 can be deformed as necessary. For example, each of the front surface 442 and the rear surface 444 may be a curved surface.

[0041] Hereinafter, a method for manufacturing the solid electrolytic capacitor 10 (see FIGS. 1 and 2) of the present embodiment will be described.

[0042] Referring to FIGS. 1 and 2, generally, it is difficult to increase the volume efficiency of the anode body (the ratio of the volume occupied by the anode body to the volume of the entire solid electrolytic capacitor including the exterior resin) in a small and thin solid electrolytic capacitor 10 as in the present embodiment. On the other hand, as will be described later, according to the manufacturing method of the present embodiment, even if the solid electrolytic capacitor 10 is small and thin, the volume efficiency of the anode body 20 can be increased, thereby improving the characteristics.

[0043] Referring to FIG. 4 in combination with FIGS. 1 and 2, the solid electrolytic capacitor 10 of the present embodiment is manufactured by four steps: a preparation step (S10), an opposing step (S20), a welding step (S30), and an exterior step (S40). However, the manufacturing method described below is merely an example, and the manufacturing method of the solid electrolytic capacitor 10 can be variously deformed. For example, a plurality of solid electrolytic capacitors 10 may be manufactured together.

[0044] First, in the preparation step (S10), each of the three components of the solid electrolytic capacitor 10, namely the main body 12, the anode lead frame 40, and the cathode lead frame 60, is manufactured and prepared. The prepared main body 12 has the shape depicted in FIG. 2. Each of the prepared anode lead frame 40 and cathode lead frame 60 is a single metal plate having a predetermined shape as shown in FIG. 5. For example, each of the base 42 and the rising portion 44 of the anode lead frame 40 extends along the horizontal plane (XY plane). Similarly, the entire cathode lead frame 60 extends along the horizontal plane.

[0045] Next, referring to FIG. 4 in combination with FIGS. 5 to 7, in the facing step (S20), the rising portion 44 of the anode lead frame 40 is bent upward so as to extend along the vertical plane (YZ plane). Similarly, the rear portion of the cathode lead frame 60 is bent upward so as to extend along the vertical plane. Next, the main body 12 is placed on the base 42 of the anode lead frame 40 and the portion of the cathode lead frame 60 that extends along the horizontal plane (XY plane). At this time, the front portion of the main body 12 is placed on the base 42 via an insulating member (not shown). Also, the rear portion of the main body 12 is fixed to the cathode lead frame 60 by a conductive adhesive 70. As a result, the cathode layer 50 of the main body 12 is electrically connected to the cathode lead frame 60 via the conductive adhesive 70.

[0046] Referring to FIGS. 6 and 7, as a result of the facing step (see FIG. 4), the rear surface 444 of the rising portion 44 faces the front end 32 of the anode lead 30. The illustrated rear surface 444 of the rising portion 44 is in contact with the front end 32 of the anode lead 30. However, the present invention is not limited to this. For example, a small gap may be formed between the rear surface 444 of the rising portion 44 and the front end 32 of the anode lead 30. On the other hand, the front end 32 of the anode lead 30 may abut against the rear surface 444 of the rising portion 44 and push the rear surface 444 forward.

[0047] Among the rear surface 444 of the rising portion 44, the portion facing the front end 32 of the anode lead 30 without or with a distance therebetween is a predetermined region 447 (see FIG. 3) that is laser-welded to the front end 32 of the anode lead 30 as will be described later. That is, the manufacturing method of the solid electrolytic capacitor 10 of the present embodiment includes an opposing step (see FIG. 4) of opposing the predetermined region 447 on the rear surface 444 of the rising portion 44 and the front end 32 of the anode lead 30 without or with a distance therebetween. The predetermined region 447 of the present embodiment has a circular shape corresponding to the front end 32 of the anode lead 30.

[0048] Referring to FIG. 5, according to the present embodiment, two U-shaped groove portions 46 are respectively formed on both sides in the lateral direction of the rising portion 44. Each of the groove portions 46 is located between the rising portion 44 and the leg portion 424 in the lateral direction. According to this structure, it is easy to bend the rising portion 44 so as to extend along the vertical plane (YZ plane). However, the present invention is not limited to this. For example, the anode lead frame 40 may not be provided with the leg portion 424. That is, the entire front edge of the base portion 42 may be connected to the rising portion 44.

[0049] Next, referring to FIG. 4 in combination with FIGS. 2 and 3, in the welding step (S30), the front end 32 of the anode lead 30 is laser-welded to the rear surface 444 of the rising portion 44. Referring to FIG. 2 in combination with FIG. 3, in the laser welding of the present embodiment, the laser beam LL is irradiated from a predetermined irradiation position RP toward the predetermined region 447 of the rear surface 444. Specifically, the laser beam LL is irradiated toward the center of the predetermined region 447 through the upper end portion of the front end 32 of the anode lead 30. When the laser beam LL is irradiated as described above, the front end 32 of the anode lead 30 and the rear surface 444 of the rising portion 44 are partially melted and welded to each other. As a result, the anode terminal 41 of the anode lead frame 40 is electrically connected to the anode body 20 through the anode lead 30.

[0050] The irradiation position RP of the present embodiment is located above and behind the starting portion 44. That is, the manufacturing method of the solid electrolytic capacitor 10 of the present embodiment irradiates the laser light LL from the irradiation position RP located above the starting portion 44 and behind the starting portion 44 toward a predetermined region 447 of the starting portion 44, and includes a welding step (see FIG. 4) of welding the starting portion 44 and the front end 32 of the anode lead 30.

[0051] Next, referring to FIG. 4 in combination with FIGS. 1 and 2, in the exterior step (S40), the exterior resin 18 is molded from the resin. Specifically, the main body portion 12 to which the anode lead frame 40 and the cathode lead frame 60 are fixed is disposed inside a mold (not shown). Next, a sol-like thermosetting resin is injected into the mold. Next, the thermosetting resin is heated and cured. As a result, the main body portion 12, the anode lead frame 40, and the cathode lead frame 60 are completely covered with the exterior resin 18 except for the anode terminal 41 and the cathode terminal 61. At this time, the solid electrolytic capacitor 10 is manufactured.

[0052] Referring to FIGS. 2 and 8, according to the present embodiment, as described above, the front end 32 of the anode lead 30 is opposed to the rear surface 444 of the starting portion 44 and welded. According to this manufacturing method, when the manufactured solid electrolytic capacitor 10 is covered with the exterior resin 18, the space occupied by the anode lead frame 40 can be reduced, and the front surface 22 of the anode body 20 can be brought closer to the front surface 182 of the exterior resin 18. That is, the space between the front surface 22 of the anode body 20 and the front surface 182 of the exterior resin 18 can be reduced. As a result, the volume efficiency of the anode body 20 can be increased, and thereby, a solid electrolytic capacitor 10 having excellent characteristics can be obtained.

[0053] The above-described laser welding is suitable for the small and thin solid electrolytic capacitor 10. However, generally, during laser welding, there is a risk that the laser beam LL scatters and damages the anode body 20. On the other hand, according to the present embodiment, when welding the rising portion 44 and the front end 32 of the anode lead 30, the laser beam LL is irradiated from the irradiation position RP located above and behind the rising portion 44. That is, the laser beam LL is irradiated onto the rising portion 44 from the side where the main body portion 12 exists in the front-rear direction. According to this irradiation method, it is easy to prevent damage to the main body portion 12. Further, by bringing the irradiation angle (angle with respect to the front-rear direction) of the laser beam LL closer to 90°, the space between the front surface 22 of the anode body 20 and the front surface 182 of the outer resin 18 can be further reduced.

[0054] Moreover, according to the present embodiment, by only welding the small front end 32 of one anode lead 30 to the rising portion 44, the anode body 20 is electrically connected to the anode lead frame 40. Specifically, the laser beam LL only needs to melt the upper end portion of the front end 32 and a part of the low-melting-point anode lead frame 40. That is, according to the present embodiment, reliable welding can be achieved with relatively little irradiation energy, and while preventing deterioration of the characteristics of the solid electrolytic capacitor 10 caused by the irradiation of the laser beam LL, the anode body 20 can be electrically connected to the anode lead frame 40.

[0055] Summarizing the above description, according to the present embodiment, there is provided a new manufacturing method for laser-welding the anode lead 30 to the anode lead frame 40, which is a manufacturing method suitable for manufacturing a solid electrolytic capacitor 10 with excellent characteristics. Further, the solid electrolytic capacitor 10 manufactured by the above-described manufacturing method has a larger volume efficiency than before. That is, according to the present embodiment, there is provided a solid electrolytic capacitor 10 in which the anode lead 30 is laser-welded to the anode lead frame 40 and having excellent characteristics.

[0056] In particular, according to the present embodiment, it is possible to provide a solid electrolytic capacitor 10 that is small and thin while having a large volume efficiency, and it is also possible to provide a manufacturing method suitable for the solid electrolytic capacitor 10. For example, the size (length) of the solid electrolytic capacitor 10 in the front-rear direction of the present embodiment is about 3.5 mm, and the distance D1 between the front surface 182 of the exterior resin 18 and the front surface 22 of the anode body 20 is 0.3 mm or more and 0.5 mm or less. According to the present embodiment, the distance D1 can be made 15% or less of the length of the solid electrolytic capacitor 10, thereby increasing the volume efficiency of the anode body 20.

[0057] Hereinafter, the manufacturing method of the present embodiment will be described in more detail.

[0058] From the viewpoint of increasing the volume efficiency of the anode body 20, it is preferable that the distance D1 between the front surface 182 of the exterior resin 18 and the front surface 22 of the anode body 20 is as small as possible. However, when the distance D1 is reduced, the distance D2 between the front surface 22 of the anode body 20 and the rear surface 444 of the rising portion 44 also becomes smaller. Generally, when the distance D2 is too small, laser welding may become difficult, and the anode body 20 may be damaged due to laser welding.

[0059] For example, according to a general YAG laser, if the irradiation energy of the laser beam LL is increased, the anode body 20 may be damaged. More specifically, the rising portion 44 may be largely vaporized, and the vaporized gas may adhere to the front surface 22 of the anode body 20, deteriorating the anode body 20. However, if the irradiation energy of the laser beam LL is reduced, there is a risk that welding cannot be performed reliably. That is, if the irradiation energy of the laser beam LL is reduced, a so-called open defect may occur.

[0060] On the other hand, the laser beam LL of the present embodiment is generated by a pulsed fiber laser. The pulsed fiber laser is likely to generate a laser beam LL with a small spot diameter. By reducing the spot diameter, it is easy to increase the density of the irradiation energy while reducing the irradiation energy.

[0061] Specifically, referring to FIG. 3 in combination with FIG. 2, the laser beam LL of the present embodiment is focused on a focal point 448 located at the center of a predetermined region 447. The size of the minor axis of the focal point 448 of the laser beam LL in the predetermined region 447 is 0.01 mm or more and 0.05 mm or less. That is, the spot diameter of the laser beam LL of the present embodiment is 0.01 mm or more and 0.05 mm or less. The laser beam LL of the present embodiment has a small spot diameter as described above, and thus has a small irradiation energy as a whole.

[0062] By generating the laser beam LL by the pulsed fiber laser as described above, it is easy to control the irradiation energy. However, the method for generating the laser beam LL in the present invention is not particularly limited.

[0063] According to the present embodiment, while visually recognizing the front end 32 of the anode lead 30, the front end 32 of the anode lead 30 and the rear surface 444 of the rising portion 44 can be surely welded by a relatively small irradiation energy. Therefore, the anode body 20 can be prevented from being damaged without providing a special layer such as a light reflection layer on the front surface 22 of the anode body 20. That is, according to the present embodiment, the manufacturing cost of the solid electrolytic capacitor 10 can be reduced.

[0064] Referring to FIG. 8, the lower end 38 of the anode lead 30 of the present embodiment extends straight along the front-rear direction. The front end 32 of the anode lead 30 is a plane parallel to the vertical plane (YZ plane), and in the opposed step (see FIG. 4), it faces and is in surface contact with the rear surface 444 of the rising portion 44 which is a plane parallel to the vertical plane.

[0065] According to the above arrangement, it is easy to surely weld with a relatively small irradiation energy. Specifically, the front end 32 and the rear surface 444 can be surely welded by the laser beam LL having a small irradiation energy while reducing the melting of the anode lead 30 and the vaporization of the rising portion 44. However, the present invention is not limited thereto. For example, the arrangements of the anode lead 30 and the rising portion 44 can be variously deformed as described below.

[0066] Referring to FIG. 9, in the opposing step (see FIG. 4), a gap GP may be formed between the rear surface 444 of the rising portion 44 and the front end 32 of the anode lead 30. When the gap GP is formed, it is preferable that the gap GP widens upward. Also, the angle θ1 formed by the rear surface 444 of the rising portion 44 and the front end 32 of the anode lead 30 is preferably as small as possible from the viewpoint of preventing open defects while increasing the irradiation angle of the laser beam LL. More specifically, the angle θ1 is preferably 13° or less.

[0067] Summarizing the above description, in the opposing step (see FIG. 4), when a gap GP is formed between the rear surface 444 of the rising portion 44 and the front end 32 of the anode lead 30, the gap GP widens upward, and the angle θ1 formed by the rear surface 444 of the rising portion 44 and the front end 32 of the anode lead 30 is preferably 13° or less.

[0068] The front end 32 of the anode lead 30 may be obliquely intersecting with respect to the lower end 38 of the anode lead 30. However, when the angle θ2 formed by the front end 32 of the anode lead 30 and the lower end 38 of the anode lead 30 is too small, it is difficult to apply the laser beam LL (see FIG. 2) having a large irradiation angle to the upper end portion of the front end 32 of the anode lead 30, and it is difficult to weld the front end 32 and the rear surface 444 of the rising portion 44. Therefore, the angle θ2 is preferably closer to 90°. More specifically, the angle θ2 is preferably 80° or more. Also, when the angle θ2 exceeds 90°, the gap GP widens downward. According to this structure, during laser welding, the lower part of the rising portion 44 may vaporize, and the vaporized gas may adhere to the front surface 22 of the anode body 20, deteriorating the anode body 20. Therefore, the angle θ2 is preferably 90° or less.

[0069] Summarizing the above description, in the opposing step (see FIG. 4), the angle θ2 formed by the front end 32 of the anode lead 30 and the lower end 38 of the anode lead 30 is preferably 80° or more. Also, in the opposing step (see FIG. 4), the angle θ2 formed by the front end 32 of the anode lead 30 and the lower end 38 of the anode lead 30 is preferably 90° or less.

[0070] In the opposing step (see FIG. 4), if the rising portion 44 is bent too far backward, when the main body portion 12 is placed on the anode lead frame 40, the front end 32 of the anode lead 30 may hit the rising portion 44. Therefore, it is preferable that the rising portion 44 extends substantially parallel to the vertical plane (YZ plane). More specifically, in the opposing step, the angle θ3 formed by the virtual line IL extending forward from the lower end 48 of the rising portion 44 and the rear surface 444 of the rising portion 44 is preferably 93° or less.

[0071] Hereinafter, the solid electrolytic capacitor 10 (see FIG. 1) of the present embodiment will be described.

[0072] As shown in FIG. 6, the rising portion 44 of the present embodiment has a size larger than the front end 32 of the anode lead 30 in the lateral direction. Further, as shown in FIG. 3, two notches 446 are formed in the rising portion 44. The two notches 446 are respectively formed at both ends of the rising portion 44 in the lateral direction. Each of the notches 446 is recessed inward of the rising portion 44 in the lateral direction.

[0073] Referring to FIG. 2, according to the manufacturing method described above, the anode lead 30 and the rising portion 44 are fixed to each other only at the welding portion near the front end 32 of the anode lead 30. If the notch 446 is not formed, for example, when an upward force is applied to the solid electrolytic capacitor 10 mounted on a circuit board (not shown), an upward force is applied to the rising portion 44 fixed to the circuit board and the anode lead 30 fixed to the rising portion 44. As a result, force is concentrated on the welding portion between the anode lead 30 and the rising portion 44, and there is a risk of open failure.

[0074] On the one hand, according to this embodiment, a notch 446 is formed, and resin is embedded inside the notch 446. According to this structure, the force applied to the solid electrolytic capacitor 10 can be dispersed, and the upward force applied to the anode lead 30 can be reduced. As a result, the force applied to the welded part between the anode lead 30 and the rising part 44 can be reduced. Further, the notch 446 functions as an anchor for fixing the anode lead frame 40 to the exterior resin 18, whereby the main body part 12, the anode lead frame 40, and the cathode lead frame 60 can be reliably fixed inside the exterior resin 18. In particular, since the two notches 446 are respectively provided at both ends in the lateral direction of the rising part 44, a stable anchor effect can be obtained.

[0075] The notch 446 of this embodiment is formed as described above and functions as described above. However, the present invention is not limited to this. For example, the shape of each of the notches 446 is not limited. The two notches 446 may be at different positions in the vertical direction. Further, the notch 446 may be provided as needed. For example, without providing the notch 446, the size in the lateral direction of the rising part 44 may be increased upward. Even with this structure, the same effect as in the case of providing the notch 446 can be obtained.

[0076] Referring to FIGS. 10 and 11, the solid electrolytic capacitor 10 of this embodiment is manufactured as described above. Accordingly, the front end 32 of the anode lead 30 is welded to a predetermined region 447 on the rear surface 444 of the rising part 44. The gap GP (see FIG. 9) located between the front end 32 and the rear surface 444 is at least partially filled by the melted anode lead 30. Further, a laser mark LM is formed on at least one of the front end 32 of the anode lead 30 and the predetermined region 447 of the rising part 44.

[0077] The laser mark LM is a dent formed due to laser welding. In other words, the laser mark LM is a notch in the anode lead 30 formed due to laser welding. A part of the illustrated laser mark LM is located at the upper end of the front end 32 of the anode lead 30 and is recessed downward. Another part of the laser mark LM is located at the upper end of the predetermined region 447 and is slightly recessed forward. The part where the laser mark LM is formed is made of an alloy of tantalum and iron and is discolored.

[0078] The illustrated laser mark LM is formed as described above. However, the illustrated laser mark LM is only an example drawn schematically, and the specific position, shape, and size of the actual laser mark LM vary widely. By the fact that the laser mark LM (i.e., the dent formed due to laser welding) is formed in at least one of the front end 32 and the predetermined region 447, it can be inferred that the solid electrolytic capacitor 10 is manufactured by the aforementioned manufacturing method.

[0079] Referring to FIGS. 10 and 12, a recess 449 is formed in the front surface 442 of the illustrated rising portion 44. The recess 449 is a trace left by the laser beam LL passing through the rising portion 44 forward and downward. That is, the recess 449 is also a kind of laser mark. Referring to FIG. 12 in combination with FIG. 11, the recess 449 is at a position corresponding to the predetermined region 447 in the vertical plane (YZ plane) and is recessed backward from the front surface 442. Referring to FIG. 2, the recess 449 formed as described above functions as an anchor for fixing the anode lead frame 40 to the exterior resin 18, similar to the notch 446. Also, by the fact that the recess 449 is formed in the front surface 442 of the rising portion 44, it can be inferred that the solid electrolytic capacitor 10 is manufactured by the aforementioned manufacturing method.

[0080] Referring to FIG. 12, the recess 449 of the present embodiment has an elliptical shape. The recess 449 has a width (first size) WT in the horizontal direction and a height (second size) HT in the vertical direction. The second size HT is larger than the first size WT. More specifically, the second size HT is at least twice the first size WT. However, the present invention is not limited thereto. The shape, size, and arrangement of the recess 449 vary depending on the irradiation direction and irradiation energy of the laser beam LL (see FIG. 10). Also, the recess 449 may not be formed.

[0081] Referring to FIG. 2, if the anode lead 30 is laser welded to the anode lead frame 40 over a wide area with a large irradiation energy, most of the rising portion 44 of the anode lead frame 40 may melt. On the other hand, according to the present embodiment, since laser welding is performed with a laser beam LL having a small irradiation energy, the rising portion 44 hardly melts, and the shape of the rising portion 44 before laser welding is maintained. Therefore, the shape of the rising portion 44 can be designed relatively freely without considering the influence of laser welding. For example, as described above, two notches 446 can be formed in the rising portion 44.

[0082] Referring to FIGS. 10 to 12, as described above, since the laser mark LM is formed on at least one of the front end 32 of the anode lead 30 and the predetermined region 447 of the rising portion 44, it can be inferred that the front end 32 of the anode lead 30 is welded to the predetermined region 447 of the rising portion 44 by the manufacturing method of the present embodiment. However, the present invention is not limited thereto. As long as the anode lead 30 extending forward from the front surface 22 of the anode body 20 is welded to the rising portion 44 of the anode lead frame 40, the volume efficiency of the solid electrolytic capacitor 10 can be made larger than before. That is, the solid electrolytic capacitor 10 may be manufactured by a manufacturing method different from the manufacturing method of the present embodiment.

[0083] Hereinafter, the conductive adhesive 70 (see FIG. 7) of the present embodiment will be described.

[0084] Referring to Fig. 7, in the opposing step (see Fig. 4), the cathode layer 50 at the rear of the main body 12 is fixed to the cathode lead frame 60 by the conductive adhesive 70. Specifically, first, the conductive adhesive 70 is applied to the cathode lead frame 60. Next, the cathode layer 50 is placed on the conductive adhesive 70. Next, the solid electrolytic capacitor 10 during manufacturing is heated at a temperature much lower than the soldering temperature to cure the conductive adhesive 70. As a result, the cathode layer 50 and the cathode lead frame 60 are fixed to each other and electrically connected. According to this embodiment, the cathode layer 50 can be electrically connected to the cathode lead frame 60 while preventing deterioration of the characteristics of the solid electrolytic capacitor 10 due to heating.

[0085] The conductive adhesive 70 of this embodiment is not particularly limited. For example, the conductive adhesive 70 may be a commonly used silver paste, or may be a conductive metal paste (metal melting type paste) different from the silver paste.

[0086] The silver paste is an adhesive in which silver particles are dispersed in a main component containing a thermosetting resin and a solvent. When the silver paste is heated, the solvent volatilizes, the main component shrinks, and the silver particles come into contact with each other. As a result, the silver paste after heat curing has conductivity. However, when the main component shrinks, the entire conductive adhesive 70 shrinks. As a result, the conductive adhesive 70 may peel off from the cathode layer 50 or the cathode lead frame 60. In order to firmly connect the cathode layer 50 and the cathode lead frame 60 with the silver paste, for example, it is necessary to form an anchor structure such as unevenness on the cathode lead frame 60. The anchor structure may increase the size of the solid electrolytic capacitor 10.

[0087] The conductive metal paste is an adhesive in which metal particles including low melting point metal particles are dispersed in a main component containing a thermosetting resin and substantially no solvent. When the conductive metal paste is heated, the low melting point metal particles melt and connect the metal particles to each other. As a result, the conductive metal paste after thermosetting has conductivity. That is, the conductive metal paste is a metal melting type paste. Further, when the conductive metal paste is heated, the conductive metal paste hardly shrinks. Therefore, the cathode layer 50 and the cathode lead frame 60 can be firmly connected without forming an anchor structure on the cathode lead frame 60. That is, the solid electrolytic capacitor 10 can be easily made small and thin. Also, the connection by the conductive metal paste has less variation in the connection strength between the cathode layer 50 and the cathode lead frame 60 compared to the connection by the silver paste. That is, the cathode layer 50 and the cathode lead frame 60 can be electrically and stably connected by the conductive metal paste.

[0088] According to the present embodiment, the base portion 42 of the anode lead frame 40 is located directly below the cathode layer 50 at the front portion of the main body portion 12. In order to surely insulate the base portion 42 and the cathode layer 50 from each other, it is necessary to make the distance in the vertical direction between the base portion 42 and the cathode layer 50 relatively large. That is, the size (height) in the vertical direction of the gap between the cathode lead frame 60 and the cathode layer 50 inevitably becomes large. The conductive metal paste is suitable for filling such a relatively large gap. On the other hand, when the height of the gap can be reduced, a silver paste may be used.

Description of reference numerals

[0089] 10 Solid electrolytic capacitor 12 Main body portion 18 Exterior resin 182 Front surface 20 Anode body 22 Front surface 30 Anode lead 32 Front end 38 Lower end 40 Anode lead frame 41 Anode terminal 42 Base portion 422 Main portion 424 Foot 44 Uplifting part 442 Front 444 Rear 446 Notch 447 Predetermined area 448 Light-gathering point 449 Concave part 46 Groove part 48 Lower end 50 Cathode layer 60 Cathode lead frame 61 Cathode terminal 70 Conductive adhesive RP Irradiation position GP Gap IL Virtual line LL Laser beam LM Laser mark

Claims

1. A method for manufacturing a solid electrolytic capacitor including an anode body, an anode lead, and an anode lead frame, comprising the steps of: The anode lead extends forward from a front surface of the anode body in a front-rear direction, the anode lead frame has a raised portion, an opposing step for opposing a predetermined region on a rear surface of the raised portion to a front end of the anode lead; a welding step of irradiating a laser beam from an irradiation position located above and behind the rising portion in a vertical direction perpendicular to the front-rear direction toward the predetermined region of the rising portion to weld the rising portion and the front end of the anode lead; Equipped Manufacturing method.

2. The method according to claim 1, In the facing step, when a gap is formed between the rear surface of the rising portion and the front end of the anode lead, the gap widens upward, and an angle formed between the rear surface of the rising portion and the front end of the anode lead is 13° or less. Manufacturing method.

3. The method according to claim 2, In the facing step, the angle between the front end of the anode lead and the lower end of the anode lead is 80° or more. Manufacturing method.

4. The method according to claim 1, In the facing step, an angle formed between an imaginary line extending forward from a lower end of the rising portion and the rear surface of the rising portion is 93° or less. Manufacturing method.

5. The method according to claim 1, In the facing step, the angle between the front end of the anode lead and the lower end of the anode lead is 90° or less. Manufacturing method.

6. The method according to any one of claims 1 to 5, The size of the minor axis of the focal point of the laser light in the predetermined region is 0.01 mm or more and 0.05 mm or less. Manufacturing method.

7. A solid electrolytic capacitor comprising an anode body, an anode lead, and an anode lead frame, The anode lead extends forward from a front surface of the anode body in a front-rear direction, the anode lead frame has a raised portion, a front end of the anode lead is welded to a predetermined region on a rear surface of the raised portion; A laser mark is formed on at least one of the front end and the predetermined region of the rising portion of the anode lead. Solid electrolytic capacitor.

8. 8. The solid electrolytic capacitor according to claim 7, the rising portion has a size larger than the front end of the anode lead in a lateral direction perpendicular to the front-rear direction, The raised portion has two notches formed therein, The two notches are formed at both ends of the raised portion in the lateral direction, Each of the notches is recessed toward the inside of the raised portion in the lateral direction. Solid electrolytic capacitor.

9. 8. The solid electrolytic capacitor according to claim 7, A recess is formed on the front surface of the raised portion, The recess is located at a position corresponding to the predetermined area on a vertical plane perpendicular to the front-rear direction, and is recessed rearward. Solid electrolytic capacitor.

10. 10. The solid electrolytic capacitor according to claim 9, The recess has an elliptical shape, the recess has a first size in a lateral direction perpendicular to the front-rear direction and a second size in a vertical direction perpendicular to both the front-rear direction and the lateral direction, The second size is greater than the first size. Solid electrolytic capacitor.

11. 11. The solid electrolytic capacitor according to claim 10, The second size is greater than or equal to twice the first size. Solid electrolytic capacitor.

12. The solid electrolytic capacitor according to any one of claims 7 to 11, the solid electrolytic capacitor is provided with an exterior resin, the anode body and the anode lead are located inside the exterior resin, The distance between the front surface of the exterior resin and the front surface of the anode body is 0.3 mm or more and 0.5 mm or less. Solid electrolytic capacitor.

13. The solid electrolytic capacitor according to any one of claims 7 to 11, a cathode layer and a cathode lead frame, the cathode layer is electrically connected to the cathode lead frame via a conductive adhesive; The conductive adhesive is a conductive metal paste. Solid electrolytic capacitor.

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