Solid electrolytic capacitor and method for manufacturing a 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 comprising 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 comprising an anode body, an anode wire (anode lead), and an anode terminal portion (anode lead frame). An organic electrolyte layer is provided on a front end of the anode body. The organic electrolyte layer is covered by a light reflection layer. The anode lead frame is positioned forward 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 resulting from reflection of laser light during laser welding is prevented, whereby deterioration of the characteristics of the solid electrolytic capacitor is prevented. [Prior Art Literature] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent No. 5078827 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] There is a demand 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 the solid electrolytic capacitor.

[0006] Therefore, the present invention aims to provide a novel manufacturing method for laser welding anode leads to an anode lead frame, which is suitable for manufacturing solid electrolytic capacitors with excellent characteristics. Furthermore, the present invention aims to provide a solid electrolytic capacitor in which anode leads are laser-welded to an anode lead frame, which has excellent characteristics. [Means for solving the problem]

[0007] The present invention provides a first manufacturing method, A method for manufacturing a solid electrolytic capacitor comprising an anode body, anode leads, and an anode lead frame, The anode lead extends forward from the front surface in the front-to-back direction of the anode body. The anode lead frame has a raised portion, A facing step that brings a predetermined region on the rear surface of the rise portion and the front end of the anode lead facing each other, A welding step in which a laser beam is irradiated from an irradiation position located above and behind the raised portion in the vertical direction perpendicular to the front-rear direction toward the predetermined area of ​​the raised portion, thereby welding the raised portion and the front end of the anode lead; Equipped with To provide a manufacturing method.

[0008] The present invention provides a second manufacturing method, which is the first manufacturing method, In the aforementioned opposing step, if a gap is formed between the rear surface of the riser portion and the front end of the anode lead, the gap widens upward, and the angle between the rear surface of the riser portion and the front end of the anode lead is 13° or less. To provide a manufacturing method.

[0009] The present invention provides a third manufacturing method, which is a second manufacturing method, In the aforementioned opposing step, the angle between the front end and the lower end of the anode lead is 80° or greater. To provide a manufacturing method.

[0010] The present invention provides a fourth manufacturing method, which is the first manufacturing method, In the aforementioned opposing step, the angle between the imaginary line extending forward from the lower end of the rising portion and the rear surface of the rising portion is 93° or less. To provide a manufacturing method.

[0011] The present invention provides a fifth manufacturing method, which is the first manufacturing method, In the aforementioned opposing step, the angle between the front end and the lower end of the anode lead is 90° or less. To provide a manufacturing method.

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

[0013] The present invention relates to a first solid electrolytic capacitor, A solid electrolytic capacitor comprising an anode body, an anode lead, and an anode lead frame, The anode lead extends forward from the front surface in the front-to-back direction of the anode body. The anode lead frame has a raised portion, The front end of the anode lead is welded to a predetermined area on the rear surface of the rise portion. A laser mark is formed on at least one of the predetermined region of the front end and the rising portion of the anode lead. We provide solid electrolytic capacitors.

[0014] The present invention provides a second solid electrolytic capacitor, which is a first solid electrolytic capacitor, The aforementioned risen portion has a size larger than the front end of the anode lead in the lateral direction perpendicular to the front-rear direction. Two notches are formed in the rising portion, the two notches are respectively formed at both ends of the rising portion in the lateral direction, each of the notches is recessed toward the inner side of the rising portion in the lateral direction A solid electrolytic capacitor is provided.

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

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

[0017] The present invention provides, as a fifth solid electrolytic capacitor, the fourth solid electrolytic capacitor, wherein the second size is at least twice the first size A solid electrolytic capacitor is provided.

[0018] The present invention provides, as a sixth solid electrolytic capacitor, any one of the first to fifth solid electrolytic capacitors, wherein the solid electrolytic capacitor comprises an exterior resin, the anode body and the anode lead are located inside the exterior resin, a distance between a front surface of the exterior resin and the front surface of the anode body is not less than 0.3 mm and not more than 0.5 mm We provide solid electrolytic capacitors.

[0019] The present invention provides a seventh solid electrolytic capacitor, which is any of the first to fifth solid electrolytic capacitors. It comprises 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. We provide solid electrolytic capacitors. [Effects of the Invention]

[0020] According to the present invention, the front end of the anode lead is welded to the rear surface of the raised portion. With this manufacturing method, when the manufactured solid electrolytic capacitor is covered with an outer 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 outer resin. As a result, the volumetric efficiency of the anode body in the solid electrolytic capacitor including the outer resin can be increased, thereby enabling the production of a solid electrolytic capacitor with excellent characteristics. Furthermore, when welding the raised portion and the front end of the anode lead, the laser beam is irradiated from an irradiation position located above and behind the raised portion. With this irradiation method, welding can be reliably performed with relatively little irradiation energy, preventing deterioration of the characteristics of the solid electrolytic capacitor.

[0021] In summary, the present invention provides a novel manufacturing method for laser welding anode leads to an anode lead frame, which is suitable for manufacturing solid electrolytic capacitors with excellent characteristics. Furthermore, solid electrolytic capacitors manufactured by the above-described manufacturing method have excellent characteristics. In other words, the present invention provides a solid electrolytic capacitor in which anode leads are laser-welded to an anode lead frame, and which has excellent characteristics. [Brief explanation of the drawing]

[0022] [Figure 1]This is a perspective view showing a solid electrolytic capacitor according to an embodiment of the present invention. The outlines of components hidden by the outer resin are drawn with dashed lines. [Figure 2] Figure 1 is a perspective view showing a solid electrolytic capacitor. The outlines of the outer resin and the hidden outlines of the anode leads are drawn with dashed lines. The irradiation position where the laser is shone is drawn with a white circle. [Figure 3] Figure 2 is a perspective view showing the anode lead frame of a solid electrolytic capacitor. The contour of the predetermined area irradiated by the laser, the contour of the focal point in the predetermined area, and the position of the leading edge of the base of the anode lead frame are drawn with dashed lines. [Figure 4] Figure 1 is a flowchart showing the manufacturing process of a solid electrolytic capacitor. [Figure 5] Figure 2 is a top view showing the anode lead frame and cathode lead frame of a solid electrolytic capacitor. The outline of the main body of the solid electrolytic capacitor is drawn with a dashed line. The main body, anode lead frame, and cathode lead frame shown are in the preparation stage. [Figure 6] Figure 5 is a top view showing the main body, anode lead frame, and cathode lead frame of a solid electrolytic capacitor. The main body, anode lead frame, and cathode lead frame shown are in opposing processes. The outline of the resin casing of the solid electrolytic capacitor is drawn with a dashed line. [Figure 7] Figure 6 is a side view showing the main body, anode lead frame, and cathode lead frame of the solid electrolytic capacitor. The outline of the outer resin is drawn with a dashed line. [Figure 8] Figure 7 is a side view showing a portion of a solid electrolytic capacitor. The hidden portion of the anode lead frame and the front surface of the casing resin are depicted with dashed lines. [Figure 9] This is a side view showing a modified example of the solid electrolytic capacitor in Figure 8. The hidden portion of the anode lead frame and the imaginary lines extending forward from the lower end of the rising portion of the anode lead frame are drawn with dashed lines. [Figure 10] Figure 2 is a schematic side view illustrating the laser marks formed on the solid electrolytic capacitor. The contours of the hidden recesses and the contours of the front ends of the anode leads before laser welding are shown with dashed lines. [Figure 11] Figure 10 is a schematic rear view illustrating the laser trace. The outline of the anode lead is shown with a dashed line. [Figure 12] This is a schematic front view illustrating the laser trace in Figure 10. [Modes for carrying out the invention]

[0023] Referring to Figures 1 and 2, the solid electrolytic capacitor 10 according to an embodiment of the present invention comprises a main body 12 having capacitance, an outer resin 18 made of an insulating material, an anode lead frame 40 made of a conductive material, and a cathode lead frame 60 made of a conductive material. The solid electrolytic capacitor 10 of this embodiment comprises the above-mentioned components. However, the present invention is not limited thereto. For example, the solid electrolytic capacitor 10 may further comprise other components in addition to the above-mentioned components.

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

[0025] In this embodiment, the vertical direction is the Z direction. In this embodiment, "up" is the +Z direction and "down" is the -Z direction. Terms related to position such as the horizontal plane and 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 this embodiment, the plane on which the main surface of the 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 has a rectangular plate shape that is generally 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 as a whole is located above the anode lead frame 40 and the cathode lead frame 60. The outer 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 inside. That is, the main body 12, the anode lead frame 40 and the cathode lead frame 60 are embedded inside the outer resin 18. However, the anode lead frame 40 and the cathode lead frame 60 are partially exposed to the outside of the outer resin 18.

[0027] Referring to Figure 2, the exposed portion of the anode lead frame 40 that is exposed from the outer resin 18 functions as the anode terminal 41, and the exposed portion of the cathode lead frame 60 that is exposed from the outer 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 soldered to a conductive pattern (not shown) formed on the upper surface of a circuit board (not shown), for example.

[0028] The main body 12 comprises 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 comprises an anode body 20, an anode lead 30, and a cathode layer 50. The anode body 20 in this embodiment comprises 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 in this embodiment comprises 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, anode lead 30, and cathode layer 50 are located inside the outer resin 18. More specifically, the anode body 20, anode lead 30, and cathode layer 50 are completely embedded inside the outer 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-to-back direction perpendicular to the vertical direction. In this embodiment, the front-to-back direction is the X direction. In this embodiment, "front" is the +X direction and "back" is the -X direction.

[0030] The anode lead 30 in this embodiment has a cylindrical shape that extends along the front-rear direction. The rear part of the anode lead 30 is embedded inside the anode body 20, and the front part 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 in the front-rear direction of the anode body 20.

[0031] The anode lead 30 has a front end 32, which is the cut surface during 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. Before welding, the front end 32 is a plane parallel to the vertical plane (YZ plane) perpendicular 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 12 in the vertical direction. For example, the size of the main body 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 12 of this embodiment has the structure described above and can be manufactured by a conventional manufacturing method, such as the one disclosed in Patent Document 1. However, the structure and manufacturing method of the main body 12 in the present invention are not particularly limited, as long as the solid electrolytic capacitor 10 is provided with an anode body 20 that holds the anode lead 30. 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 that intersects obliquely with the front-rear direction.

[0033] Referring to Figure 5 in conjunction with Figures 2 and 3, the anode lead frame 40 and cathode lead frame 60 in this embodiment are each formed by bending a single metal piece cut into a predetermined shape from a metal plate. That is, the anode lead frame 40 and cathode lead frame 60 are each a single metal plate that has been bent.

[0034] In this embodiment, the anode lead frame 40 and the cathode lead frame 60 are each formed from a relatively easy-to-process metal such as iron or copper. Therefore, the melting points of the anode lead frame 40 and the cathode lead frame 60 are considerably lower than the melting point of the anode lead 30, which is made of tantalum. However, the materials, structure, and manufacturing methods of the anode lead frame 40 and the cathode lead frame 60 in this invention are not particularly limited. Furthermore, the cathode lead frame 60 may be provided as needed.

[0035] The anode lead frame 40 of this embodiment will be described in more detail below.

[0036] Referring to Figure 3 in conjunction with Figure 2, the anode lead frame 40 of this embodiment has a base portion 42 and a rise portion 44. The lateral size of the base portion 42 is slightly smaller than the lateral size of the main body portion 12. The lateral size of the rise portion 44 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 parts. However, the present invention is not limited thereto. For example, the anode lead frame 40 may have other parts in addition to the above-described parts.

[0037] Referring to Figure 3, the base 42 of this embodiment extends along the horizontal plane (XY plane). The base 42 has a main portion 422 and two leg portions 424. The main portion 422 has a rectangular plate shape parallel to the horizontal plane. The front edge of the main portion 422 extends along the lateral direction, which is perpendicular to both the vertical and longitudinal directions. In this embodiment, the lateral direction is the Y direction. The two leg portions 424 are connected to both sides of the front edge of the main portion 422 in the lateral direction. 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 in this embodiment has the structure described above. However, the present invention is not limited thereto, and the structure of the base portion 42 can be modified as needed. Furthermore, the base portion 42 may be provided only if necessary.

[0039] The riser portion 44 of this embodiment extends along the vertical plane (YZ plane) as a whole. More specifically, the riser portion 44 is connected to the intermediate portion in the lateral direction of the front edge of the main portion 422. The riser portion 44 extends forward from the front edge of the main portion 422, then curves in an arc and extends upward. The riser portion 44 has a front surface 442 and a rear surface 444. The front surface 442 and the rear surface 444 of this embodiment are both flat surfaces without irregularities.

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

[0041] The manufacturing method for the solid electrolytic capacitor 10 of this embodiment (see Figures 1 and 2) will be described below.

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

[0043] Referring to Figure 4 in conjunction with Figures 1 and 2, the solid electrolytic capacitor 10 of this embodiment is manufactured by four steps: a preparation step (S10), a counter-assembly step (S20), a welding step (S30), and an casing step (S40). However, the manufacturing method described below is merely an example, and the manufacturing method of the solid electrolytic capacitor 10 can be modified in various ways. For example, multiple solid electrolytic capacitors 10 may be manufactured together.

[0044] First, in the preparation step (S10), 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, are manufactured and prepared. The prepared main body 12 has the shape shown in Figure 2. The prepared anode lead frame 40 and cathode lead frame 60 are each single metal plates having a predetermined shape, as shown in Figure 5. For example, the base 42 and the rising portion 44 of the anode lead frame 40 each extend along the horizontal plane (XY plane). Similarly, the entire cathode lead frame 60 extends along the horizontal plane.

[0045] Next, referring to Figure 4 in conjunction with Figures 5 to 7, in the opposing 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 portion 12 is placed on the base portion 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 portion 12 is placed on the base portion 42 via an insulating member (not shown). The rear portion of the main body portion 12 is fixed to the cathode lead frame 60 with conductive adhesive 70. As a result, the cathode layer 50 of the main body portion 12 is electrically connected to the cathode lead frame 60 via the conductive adhesive 70.

[0046] Referring to Figures 6 and 7, as a result of the opposing step (see Figure 4), the rear surface 444 of the riser portion 44 faces the front end 32 of the anode lead 30. The rear surface 444 of the riser portion 44 shown is in contact with the front end 32 of the anode lead 30. However, the present invention is not limited thereto. For example, a small gap may be formed between the rear surface 444 of the riser 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 riser portion 444, pushing the rear surface 444 forward.

[0047] The portion of the rear surface 444 of the rise portion 44 that faces the front end 32 of the anode lead 30, either at close range or at a distance, is a predetermined region 447 (see Figure 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 this embodiment includes a facing step (see Figure 4) in which the predetermined region 447 on the rear surface 444 of the rise portion 44 and the front end 32 of the anode lead 30 face each other, either at close range or at a distance. The predetermined region 447 of this embodiment has a circular shape corresponding to the front end 32 of the anode lead 30.

[0048] Referring to Figure 5, according to this embodiment, two U-shaped grooves 46 are formed on both sides of the rise portion 44 in the lateral direction. Each of the grooves 46 is located between the rise portion 44 and the leg portion 424 in the lateral direction. This structure makes it easy to bend the rise portion 44 so that it extends along the vertical plane (YZ plane). However, the present invention is not limited thereto. For example, the anode lead frame 40 does not have to be provided with leg portions 424. That is, the entire leading edge of the base portion 42 may be connected to the rise portion 44.

[0049] Next, referring to Figure 4 in conjunction with Figures 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 rise portion 44. Referring to Figure 2 in conjunction with Figure 3, in the laser welding of this embodiment, the laser beam LL is irradiated from a predetermined irradiation position RP toward a predetermined region 447 of the rear surface 444. More specifically, the laser beam LL is irradiated from the upper end of the front end 32 of the anode lead 30 toward the center of the predetermined region 447. 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 rise portion 444 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 via the anode lead 30.

[0050] In this embodiment, the irradiation position RP is located above and behind the rise portion 44. That is, the manufacturing method of the solid electrolytic capacitor 10 in this embodiment includes a welding step (see Figure 4) in which laser light LL is irradiated from the irradiation position RP, which is located above and behind the rise portion 44, toward a predetermined region 447 of the rise portion 44, to weld the rise portion 44 and the front end 32 of the anode lead 30.

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

[0052] Referring to Figures 2 and 8, according to this embodiment, as described above, the front end 32 of the anode lead 30 is welded to the rear surface 444 of the rise portion 44. With this manufacturing method, when the manufactured solid electrolytic capacitor 10 is covered with the outer 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 outer resin 18. That is, the space between the front surface 22 of the anode body 20 and the front surface 182 of the outer resin 18 can be reduced. As a result, the volumetric efficiency of the anode body 20 can be increased, thereby obtaining a solid electrolytic capacitor 10 with excellent characteristics.

[0053] The laser welding described above is suitable for small and thin solid electrolytic capacitors 10. However, generally, during laser welding, the laser beam LL may scatter and damage the anode body 20. On the other hand, according to this embodiment, when welding the rise portion 44 and the front end 32 of the anode lead 30, the laser beam LL is irradiated from an irradiation position RP located above and behind the rise portion 44. That is, the laser beam LL is irradiated onto the rise portion 44 from the side where the main body 12 is located in the front-to-back direction. This irradiation method makes it easier to prevent damage to the main body 12. In addition, by bringing the irradiation angle of the laser beam LL (angle with respect to the front-to-back direction) 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] Furthermore, according to this embodiment, the anode body 20 is electrically connected to the anode lead frame 40 by welding only the small front end 32 of one anode lead 30 to the riser portion 44. Specifically, the laser beam LL only needs to melt the upper end of the front end 32 and a portion of the low-melting-point anode lead frame 40. In other words, according to this embodiment, welding can be reliably performed with relatively little irradiation energy, and the anode body 20 can be electrically connected to the anode lead frame 40 while preventing deterioration of the characteristics of the solid electrolytic capacitor 10 caused by irradiation with laser beam LL.

[0055] In summary, according to this embodiment, a new manufacturing method is provided in which the anode lead 30 is laser-welded to the anode lead frame 40, and a manufacturing method suitable for producing a solid electrolytic capacitor 10 with excellent characteristics can be provided. Furthermore, the solid electrolytic capacitor 10 produced by the above manufacturing method has a larger volumetric efficiency than conventional capacitors. In other words, according to this embodiment, a solid electrolytic capacitor 10 in which the anode lead 30 is laser-welded to the anode lead frame 40 can be provided, and a solid electrolytic capacitor 10 with excellent characteristics can be provided.

[0056] In particular, this embodiment provides a solid electrolytic capacitor 10 that is small and thin yet has high volumetric efficiency, and also provides a suitable manufacturing method for this solid electrolytic capacitor 10. For example, the size (length) of the solid electrolytic capacitor 10 in the front-to-back direction in this embodiment is about 3.5 mm, and the distance D1 between the front surface 182 of the outer 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 this embodiment, the distance D1 can be made 15% or less of the length of the solid electrolytic capacitor 10, thereby increasing the volumetric efficiency of the anode body 20.

[0057] The manufacturing method of this embodiment will be described in more detail below.

[0058] From the viewpoint of increasing the volumetric efficiency of the anode body 20, it is preferable that the distance D1 between the front surface 182 of the outer resin 18 and the front surface 22 of the anode body 20 be as small as possible. However, if 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 riser portion 44 also becomes smaller. Generally, if 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, with a typical YAG laser, increasing the irradiation energy of the laser beam LL may damage the anode 20. More specifically, the rising portion 44 may vaporize significantly, and the vaporized gas may adhere to the front surface 22 of the anode 20, potentially degrading the anode 20. However, decreasing the irradiation energy of the laser beam LL may result in unreliable welding. In other words, decreasing the irradiation energy of the laser beam LL may cause so-called open faults.

[0060] On the other hand, the laser light LL in this embodiment is generated by a pulsed fiber laser. A pulsed fiber laser can easily generate laser light LL with a small spot diameter. By reducing the spot diameter, it is easier to increase the irradiation energy density while reducing the irradiation energy.

[0061] For details, referring to Figure 3 in conjunction with Figure 2, the laser beam LL of this embodiment is focused at a focal point 448 located in 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 this embodiment is 0.01 mm or more and 0.05 mm or less. As described above, the laser beam LL of this embodiment has a small spot diameter and therefore has a small irradiation energy overall.

[0062] As described above, generating laser light LL using a pulsed fiber laser makes it easier to control the irradiation energy. However, the method for generating laser light LL in this invention is not particularly limited.

[0063] According to this embodiment, the front end 32 of the anode lead 30 and the rear surface 444 of the rise portion 44 can be reliably welded with relatively little irradiation energy while visually inspecting the front end 32 of the anode lead 30. Therefore, damage to the anode body 20 can be prevented without providing a special layer such as a light-reflecting layer on the front surface 22 of the anode body 20. In other words, according to this embodiment, the manufacturing cost of the solid electrolytic capacitor 10 can be reduced.

[0064] Referring to Figure 8, the lower end 38 of the anode lead 30 in this 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 opposing step (see Figure 4), 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, welding can be reliably performed with relatively little irradiation energy. Specifically, the front end 32 and the rear surface 444 can be reliably welded using laser light LL with a small irradiation energy, while reducing the melting of the anode lead 30 and vaporization of the riser portion 44. However, the present invention is not limited thereto. For example, the arrangement of the anode lead 30 and the riser portion 44 can be modified in various ways, as described below.

[0066] Referring to Figure 9, in the opposing step (see Figure 4), a gap GP may be formed between the rear surface 444 of the riser portion 44 and the front end 32 of the anode lead 30. If a gap GP is formed, it is preferable that the gap GP widens upward. Furthermore, the angle θ1 formed by the rear surface 444 of the riser 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, it is preferable that the angle θ1 is 13° or less.

[0067] To summarize the above explanation, in the opposing step (see Figure 4), if a gap GP is formed between the rear surface 444 of the riser portion 44 and the front end 32 of the anode lead 30, it is preferable that the gap GP widens upward and the angle θ1 between the rear surface 444 of the riser portion 44 and the front end 32 of the anode lead 30 is 13° or less.

[0068] The front end 32 of the anode lead 30 may be oblique to the lower end 38 of the anode lead 30. However, if the angle θ2 between the front end 32 and the lower end 38 of the anode lead 30 is too small, it becomes difficult to apply the laser beam LL (see Figure 2) with a large irradiation angle to the upper end of the front end 32 of the anode lead 30, making it difficult to weld the front end 32 to the rear surface 444 of the riser portion 44. Therefore, it is preferable that the angle θ2 is close to 90°. More specifically, it is preferable that the angle θ2 is 80° or more. Also, if the angle θ2 exceeds 90°, the gap GP widens downwards. With this structure, during laser welding, the lower part of the riser portion 44 may vaporize, and the vaporized gas may adhere to the front surface 22 of the anode body 20, potentially degrading the anode body 20. Therefore, it is preferable that the angle θ2 is 90° or less.

[0069] To summarize the above explanation, in the opposing step (see Figure 4), it is preferable that 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 80° or more. Also, in the opposing step (see Figure 4), it is preferable that 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 90° or less.

[0070] In the opposing step (see Figure 4), if the rising portion 44 is bent too far backward, the front end 32 of the anode lead 30 may abut against the rising portion 44 when the main body 12 is placed on the anode lead frame 40. Therefore, it is preferable that the rising portion 44 extends substantially parallel to the vertical plane (YZ plane). More specifically, in the opposing step, it is preferable that the angle θ3 between the imaginary 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 93° or less.

[0071] The solid electrolytic capacitor 10 of this embodiment (see Figure 1) will be described below.

[0072] As shown in Figure 6, the rise portion 44 of this embodiment is larger in size than the front end 32 of the anode lead 30 in the lateral direction. Also, as shown in Figure 3, two notches 446 are formed in the rise portion 44. The two notches 446 are formed at both ends of the rise portion 44 in the lateral direction. Each of the notches 446 is recessed inward in the lateral direction of the rise portion 44.

[0073] Referring to Figure 2, according to the manufacturing method described above, the anode lead 30 and the riser portion 44 are fixed to each other only at the weld 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 riser portion 44 fixed to the circuit board and the anode lead 30 fixed to the riser portion 44. As a result, force is concentrated at the weld between the anode lead 30 and the riser portion 44, which may cause an open circuit failure.

[0074] On the other hand, according to this embodiment, a notch 446 is formed, and resin is embedded inside the notch 446. With this structure, the force applied to the solid electrolytic capacitor 10 can be distributed, and the upward force applied to the anode lead 30 can be reduced. As a result, the force applied to the weld between the anode lead 30 and the riser portion 44 can be reduced. In addition, the notch 446 functions as an anchor to fix the anode lead frame 40 to the outer resin 18, thereby securely fixing the main body portion 12, the anode lead frame 40 and the cathode lead frame 60 inside the outer resin 18. In particular, since two notches 446 are provided at both ends of the riser portion 44 in the lateral direction, a stable anchoring effect can be obtained.

[0075] The notches 446 in this embodiment are formed and function as described above. However, the present invention is not limited thereto. For example, the shape of each of the notches 446 is not limited. The two notches 446 may be in different positions in the vertical direction. Also, the notches 446 may be provided as needed. For example, the size of the riser portion 44 in the lateral direction may be increased upward without providing the notches 446. This structure can also be used to obtain the same effect as when the notches 446 are provided.

[0076] Referring to Figures 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 rise portion 44. The gap GP (see Figure 9) located between the front end 32 and the rear surface 444 is at least partially filled by the molten anode lead 30. In addition, 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 rise portion 44.

[0077] The laser mark LM is a depression formed as a result of laser welding. In other words, the laser mark LM is a notch in the anode lead 30 formed as a result of laser welding. A portion 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 downwards. Another portion of the laser mark LM is located at the upper end of a predetermined region 447 and is slightly recessed forwards. The area where the laser mark LM is formed is made of an alloy of tantalum and iron and is discolored.

[0078] The illustrated laser trace LM is formed as described above. However, the illustrated laser trace LM is merely a schematic example, and the specific location, shape, and size of the actual laser trace LM vary considerably. The presence of a laser trace LM (i.e., a depression formed due to laser welding) on ​​at least one of the front end 32 and the predetermined region 447 suggests that the solid electrolytic capacitor 10 was manufactured by the aforementioned manufacturing method.

[0079] Referring to Figures 10 and 12, a recess 449 is formed on the front surface 442 of the illustrated rise portion 44. The recess 449 is the trace left by the laser beam LL passing forward and downward through the rise portion 44. In other words, the recess 449 is also a type of laser trace. Referring to Figure 12 in conjunction with Figure 11, the recess 449 is located in a position corresponding to a predetermined region 447 in the vertical plane (YZ plane) and is recessed toward the rear from the front surface 442. Referring to Figure 2, the recess 449 formed as described above functions as an anchor for fixing the anode lead frame 40 to the outer resin 18, similar to the notch 446. Furthermore, the formation of the recess 449 on the front surface 442 of the rise portion 44 suggests that the solid electrolytic capacitor 10 was manufactured by the aforementioned manufacturing method.

[0080] Referring to Figure 12, the recess 449 in this embodiment has an elliptical shape. The recess 449 has a width (first size) WT in the lateral 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 more than 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 light LL (see Figure 10). Also, the recess 449 may not be formed in some cases.

[0081] Referring to Figure 2, if the anode lead 30 is laser-welded to the anode lead frame 40 over a wide area with high irradiation energy, there is a risk that a large portion of the raised portion 44 of the anode lead frame 40 will melt. On the other hand, according to this embodiment, since laser welding is performed with laser light LL of low irradiation energy, the raised portion 44 hardly melts, and the shape of the raised portion 44 before laser welding is maintained. For this reason, the shape of the raised portion 44 can be designed relatively freely without considering the effects of laser welding. For example, as mentioned above, two notches 446 can be formed in the raised portion 44.

[0082] Referring to Figures 10 to 12, as mentioned above, the presence of laser marks LM on at least one of the front end 32 of the anode lead 30 and the predetermined region 447 of the rise portion 44 suggests that the front end 32 of the anode lead 30 is welded to the predetermined region 447 of the rise portion 44 by the manufacturing method of this 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 rise portion 44 of the anode lead frame 40, the volumetric efficiency of the solid electrolytic capacitor 10 can be increased compared to conventional methods. That is, the solid electrolytic capacitor 10 may be manufactured by a manufacturing method different from that of this embodiment.

[0083] The conductive adhesive 70 of this embodiment (see Figure 7) will be described below.

[0084] Referring to Figure 7, in the opposing step (see Figure 4), the cathode layer 50 at the rear of the main body 12 is fixed to the cathode lead frame 60 by conductive adhesive 70. Specifically, first, conductive adhesive 70 is applied to the cathode lead frame 60. Next, the cathode layer 50 is placed on top of the conductive adhesive 70. Then, the solid electrolytic capacitor 10 in the process of being manufactured is heated at a temperature considerably 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 in this embodiment is not particularly limited. For example, the conductive adhesive 70 may be a commonly used silver paste, or it may be a conductive metal paste (metal molten paste) different from silver paste.

[0086] 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 evaporates and the main component shrinks, causing the silver particles to come into contact with each other. As a result, the silver paste becomes conductive after heat curing. 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 silver paste, it is necessary to form an anchor structure such as irregularities on the cathode lead frame 60, for example. The anchor structure may increase the size of the solid electrolytic capacitor 10.

[0087] Conductive metal paste is an adhesive in which metal particles, including low-melting-point metal particles, are dispersed in a main component that contains a thermosetting resin and substantially no solvent. When conductive metal paste is heated, the low-melting-point metal particles melt and bond together. As a result, the conductive metal paste becomes conductive after heat curing. In other words, conductive metal paste is a metal-melting type paste. Furthermore, when conductive metal paste is heated, it 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. In other words, the solid electrolytic capacitor 10 can be made smaller and thinner. In addition, the connection strength between the cathode layer 50 and the cathode lead frame 60 is smaller when using conductive metal paste compared to when using silver paste. In other words, the cathode layer 50 and the cathode lead frame 60 can be electrically stably connected using conductive metal paste.

[0088] According to this embodiment, the base 42 of the anode lead frame 40 is located directly below the cathode layer 50 at the front of the main body 12. In order to reliably insulate the base 42 and the cathode layer 50 from each other, the vertical distance between the base 42 and the cathode layer 50 needs to be relatively large. That is, the vertical size (height) of the gap between the cathode lead frame 60 and the cathode layer 50 is inevitably large. Conductive metal paste is suitable for filling such a relatively large gap. On the other hand, if the height of the gap can be reduced, silver paste may be used. [Explanation of symbols]

[0089] 10 Solid electrolytic capacitors 12 Main body 18 Exterior resin 182 Front 20 Anode 22 Front 30 Anode Leads 32 Front end 38 Bottom end 40 Anode lead frames 41 Anode terminal 42 Base 422 Main section 424 Legs 44. Startup Department 442 Front 444 Rear 446 Notches 447 Predetermined area 448 Focusing points 449 recess 46 Groove 48 Bottom end 50 Cathode layer 60 Cathode Lead Frames 61 Cathode terminal 70 Conductive adhesive RP irradiation position GP gap IL virtual line LL laser light LM laser trace

Claims

1. A method for manufacturing a solid electrolytic capacitor comprising an anode body, anode leads, and an anode lead frame, The anode lead extends forward from the front surface in the front-to-back direction of the anode body. The anode lead frame has a raised portion, A facing step that brings a predetermined region on the rear surface of the rise portion and the front end of the anode lead facing each other, A welding step in which a laser beam is irradiated from an irradiation position located above and behind the raised portion in the vertical direction perpendicular to the front-rear direction toward the predetermined area of ​​the raised portion, thereby welding the raised portion and the front end of the anode lead; Equipped with Manufacturing method.

2. A manufacturing method according to claim 1, In the aforementioned opposing step, if a gap is formed between the rear surface of the riser portion and the front end of the anode lead, the gap widens upward, and the angle between the rear surface of the riser portion and the front end of the anode lead is 13° or less. Manufacturing method.

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

4. A manufacturing method according to claim 1, In the aforementioned opposing step, the angle between the imaginary line extending forward from the lower end of the rising portion and the rear surface of the rising portion is 93° or less. Manufacturing method.

5. A manufacturing method according to claim 1, In the aforementioned opposing step, the angle formed by the front end and the lower end of the anode lead is 90° or less. Manufacturing method.

6. A manufacturing method according to any one of claims 1 to 5, The size of the minor axis of the focal point of the laser beam 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 the front surface in the front-to-back direction of the anode body. The anode lead frame has a raised portion, The front end of the anode lead is welded to a predetermined area on the rear surface of the rise portion. A laser mark is formed on at least one of the predetermined region of the front end and the rising portion of the anode lead. Solid electrolytic capacitor.

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

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

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

11. A solid electrolytic capacitor according to claim 10, The second size is more than twice the first size. Solid electrolytic capacitor.

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

13. A solid electrolytic capacitor according to any one of claims 7 to 11, It comprises 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.

Images