JP2023133550A - Electrolytic capacitor and manufacturing method thereof - Google Patents

Abstract

To make it difficult for cracks to occur in an electrode foil when the electrode foil of an electrolyte capacitor is connected to a lead.SOLUTION: A lead 22 is arranged on one side of an electrode foil 21 in the thickness direction, and a caulking needle is inserted from one side in the thickness direction to form a burr 22b penetrating the electrode foil 21 on the lead 22. Subsequently, the burr 22b is pressure-welded from the other side in the thickness direction to connect the electrode foil 21 and the lead 22 with the pressure-welded burr 22b. Before insertion of the caulking needle, in the electrode width direction, the electrode foil 21 is located between the end of the electrode foil 21 and a connection portion 31 between the electrode foil 21 and the lead 22 by the burr 22b is formed with a circular through hole 32.SELECTED DRAWING: Figure 4

Description

The present invention relates to an electrolytic capacitor and a method for manufacturing an electrolytic capacitor.

In Patent Document 1, in order to connect an electrode foil and a lead constituting an electrolytic capacitor, the lead is arranged on one side of the electrode foil in the thickness direction, and a caulking needle is pierced from one side in the thickness direction. A burr is formed on the lead that penetrates the electrode foil in the thickness direction. Thereafter, the crimping needle is removed and the burr is pressed from the other side in the thickness direction using a push-up pin. As a result, the electrode foil is sandwiched between the lead and the burr that is pressed into contact with the lead, and the electrode foil and the lead are connected.

Japanese Patent Application Publication No. 7-106203

Here, when connecting an electrode foil and a lead as described in Patent Document 1, when the burr is pressed into contact with the burr, strain due to compressive stress is generated in the burr, and the strain due to this compressive stress is transmitted to the electrode foil. As a result, cracks may occur at the ends of the electrode foil. When a crack occurs in the electrode foil, the bonding strength between the electrode foil and the lead decreases, and in the worst case, the conduction between the electrode foil and the lead is completely cut off (open).

Furthermore, an oxide film (dielectric film) of aluminum oxide (Al ₂ O ₃ ) is usually formed on the surface of the electrode foil of an electrolytic capacitor as described in Patent Document 1. Here, the greater the thickness of the oxide film, the higher the withstand voltage of the electrolytic capacitor, and the larger the surface area of the oxide film, the greater the capacitance of the electrolytic capacitor. Therefore, in order to improve the performance of an electrolytic capacitor, the thickness and surface area of the oxide film formed on the surface of the electrode foil may be increased. On the other hand, aluminum oxide is hard and brittle. Therefore, in an electrode foil in which the thickness or surface area of the oxide film is increased, cracks are particularly likely to occur in the electrode foil when the electrode foil and the lead are joined as described above.

An object of the present invention is to provide an electrolytic capacitor and a method for manufacturing an electrolytic capacitor in which cracks are less likely to occur in the electrode foil when connecting the electrode foil and the lead.

An electrolytic capacitor according to a first aspect of the present invention includes an electrode foil extending in a first direction; and a lead drawn out in a second direction orthogonal to the electrode foil, and a burr of the lead protruding through the electrode foil in the thickness direction is pressed against the surface of the electrode foil on the other side in the thickness direction. By doing so, the electrode foil is sandwiched between the lead and the burr, the electrode foil and the lead are connected, and the end of the electrode foil and the electrode foil are connected in the second direction of the electrode foil. A through hole is provided in an edge region of the electrode foil for a portion located between the electrode foil and the connecting portion with the lead, and the diameter of the through hole is such that the diameter of the through hole is such that the diameter of the through hole is such that the diameter of the through hole is such that the diameter of the through hole is such that the diameter of the through hole is such that the diameter of the through hole is the same as that between the lead of the electrode foil and the burr. smaller than the diameter of the caulking hole formed through the area.

According to the present invention, the strain caused by the compressive stress generated in the burr and transmitted to the electrode foil when the burr is pressed is absorbed in the through hole. This can make it difficult for cracks to occur at the ends of the electrode foil in the second direction.

An electrolytic capacitor according to a second invention is the electrolytic capacitor according to the first invention, wherein the through hole is circular or elliptical. In particular, it is preferable that the through hole is circular.

When an elliptical through hole is formed in the electrode foil, the ability of the through hole to absorb compressive stress is mainly determined by the length of the ellipse in the minor axis direction. On the other hand, if the through-hole is made circular with the same diameter as the length of the short axis of the ellipse, it will maintain the same compressive stress absorption performance as the oval-shaped through-hole, but The through hole can be made smaller than in the case of an elliptical shape. By making the through-holes smaller, the area of the portion of the electrode foil where the through-holes are not formed can be made as large as possible to ensure the electrostatic capacitance of the electrolytic capacitor.

The electrolytic capacitor according to a third aspect of the present invention is the electrolytic capacitor according to the first or second aspect of the present invention, in which the through hole is connected to each of both ends of the electrode foil in the second direction of the electrode foil. They are provided at both ends of the electrode foil, with respect to the portion located between the electrode foil and the connecting portion of the lead.

According to the present invention, cracks can be made less likely to occur at both ends of the electrode foil in the second direction.

The electrolytic capacitor according to a fourth invention is the electrolytic capacitor according to any one of the first to third inventions, wherein the through hole is displaced in the first direction from a connection portion of the electrode foil with the lead. It is provided in the right part.

Strain due to compressive stress generated at the connection portion between the electrode foil and the lead propagates radially through the electrode foil, and the closer the portion of the electrode foil to the connection portion with the lead, the greater the strain due to the compressive stress. Therefore, if the distance between the through hole and the connection part between the electrode foil and the lead is short, the strain due to compressive stress will be large in the part of the electrode foil where the through hole is formed, and the strain due to compressive stress will be sufficiently absorbed by the through hole. There are things I can't do. In the present invention, the through hole is provided in a portion of the electrode foil that is shifted in the first direction from the connection portion with the lead. As a result, compared to the case where the through hole is provided at the same position in the first direction as the connection part of the electrode foil to the lead, the through hole and the connection part between the electrode foil and the lead are The distance can be increased. Thereby, the strain caused by the compressive stress can be sufficiently absorbed in the through hole.

The electrolytic capacitor according to a fifth aspect of the present invention is the electrolytic capacitor according to the fourth aspect, in which the through hole is located on both sides in the first direction of a connecting portion of the electrode foil with the lead. Each is equipped.

According to the present invention, the strain due to the compressive stress transmitted to the portions of the electrode foil connected to the leads located on both sides in the first direction can be absorbed by the through holes.

The electrolytic capacitor according to a sixth invention is the electrolytic capacitor according to the fourth or fifth invention, in which the through hole is provided at a position away from a position where the electrode foil and the lead overlap.

In the present invention, the through hole is provided in a portion away from the position where the electrode foil and the lead overlap. As a result, the distance between the through hole and the connection portion between the electrode foil and the lead can be made longer than when the through hole is provided in a portion where the electrode foil and the lead overlap. Thereby, the strain caused by the compressive stress can be sufficiently absorbed in the through hole.

A method for manufacturing an electrolytic capacitor according to a seventh aspect of the present invention includes an electrode foil extending in a first direction; A method for manufacturing an electrolytic capacitor, comprising: a lead drawn out in a second direction perpendicular to both of the electrode foil and the electrode foil; a burr forming step of forming a burr on the lead that penetrates the electrode foil in the thickness direction by inserting a crimping needle into the lead from the one side in the thickness direction; a pressure welding step of sandwiching the electrode foil between the lead and the burr to connect the electrode foil and the lead by pressure contacting a surface on the other side of the direction; Previously, in the second direction of the electrode foil, a through hole is formed in an edge region of the electrode foil in a portion located between the electrode foil and the connection portion with the lead. The diameter of the through hole is smaller than the diameter of a caulking hole formed through a region sandwiched between the lead and the burr of the electrode foil.

According to the present invention, it is possible to prevent cracks from occurring at the ends of the electrode foil when connecting the electrode foil and the lead.

1 is a front view showing the appearance of an electrolytic capacitor in an embodiment of the present invention. FIG. 1 is an exploded view showing the components of an electrolytic capacitor in an embodiment of the present invention. FIG. 2 is an explanatory diagram showing components of a capacitor element according to an embodiment of the present invention. (a) is a diagram showing the connection between an electrode foil and a lead, and (b) is a cross-sectional view taken along the line IVB-IVB in (a). (a) is a diagram showing a process of forming a through hole in an electrode foil, (b) is a diagram showing a process of setting a laminate of an electrode foil and a lead in a press machine, and (c) is a diagram showing a process of removing burrs. It is a figure which shows the process of forming, and (d) is a figure which shows the process of pressuring a burr. (a) is a diagram showing a joined body of an electrode foil and a lead according to Example 1, and (b) is a diagram showing a joined body of an electrode foil and a lead according to Comparative Example 1. (a) is a diagram showing an analytical model according to Example 2, (b) is a diagram showing an analytical model according to Example 3, and (c) is a diagram showing an analytical model according to Example 4. , (d) is a diagram showing an analytical model according to Example 5, and (e) is a diagram showing an analytical model according to Comparative Example 2.

Hereinafter, preferred embodiments of the present invention will be described.

<Configuration of electrolytic capacitor>
FIG. 1 is a front view showing the appearance of an electrolytic capacitor 1 according to an embodiment of the invention, and FIG. 2 is an exploded view showing the components of the electrolytic capacitor 1 according to an embodiment of the invention. As shown in FIG. 2, the electrolytic capacitor 1 of this embodiment includes a capacitor element 2, a case 3a, and a sealing body 3b.

The capacitor element 2 is an element that stores and releases electric charge according to its capacitance, and as shown in FIG. 2, is housed inside a case 3a.
The case 3a is a bottomed cylindrical body made of aluminum material, and is open at one end in the axial direction and closed at the other end.

The sealing body 3b is a substantially cylindrical insulating member that seals the opening of the case 3a containing the capacitor element 2, and is made of, for example, rubber or synthetic resin.

<Configuration of capacitor element>
Next, the capacitor element 2 will be explained.
FIG. 3 is an explanatory diagram showing the components of the capacitor element 2. As shown in FIG.
As shown in FIG. 3, the capacitor element 2 includes an anode foil 2x, a cathode foil 2y, a plurality of separators 2z, an anode lead 2b, a cathode lead 2a, and an element fixing tape 2t.

The anode foil 2x is a long strip-shaped electrode foil made of a valve metal such as aluminum, and as described later, an oxide film serving as a dielectric is essentially formed on the surface. The cathode foil 2y is a long strip-shaped electrode foil made of a valve metal such as aluminum, like the anode foil 2x. The anode foil 2x and the cathode foil 2y are rectangular, and for convenience of explanation below, in the rectangle, the width extending in the longitudinal direction is referred to as the width or the electrode length direction (the "first direction" of the present invention), and the longitudinal direction is referred to as the width extending in the longitudinal direction. The width extending in the direction perpendicular to the electrode will be referred to as the vertical width or the electrode width direction (the "second direction" of the present invention). The vertical widths of the anode foil 2x and the cathode foil 2y are the same, but may be different.The width of the cathode foil 2y is set longer than that of the anode foil 2x, but the width of the cathode foil is set shorter or the same. You can also set the length. Further, the anode foil 2x has a thickness of 0.05 to 0.12 mm, the cathode foil 2y has a thickness of about 0.02 to 0.05 mm, and the anode foil 2x is set to be slightly thicker.

The surface of this anode foil 2x is roughened by etching treatment (etching pits are formed) and an anodic oxide film is formed by anodic oxidation (chemical conversion). Similarly to the anode foil 2x, the cathode foil 2y is also made of aluminum or the like, and its surface is roughened (etching pits are formed) and has a natural oxide film or an anodic oxide film formed thereon. Note that the surface of the cathode foil 2y may be formed of Ti, TiN, TiC, or the like.

The separator 2z is a rectangular band-shaped electrolytic paper or nonwoven fabric, and a driving electrolyte and/or a solid electrolyte are held on both sides of the separator 2z. According to this embodiment, two separators 2z are used. The vertical widths of the two separators 2z, 2z are set to be the same, and the horizontal width of one of the separators 2z is set to be longer. Further, the vertical width of the separator 2z is set to be slightly longer than the vertical widths of the anode foil 2x and the cathode foil 2y.

The anode lead 2b is a conductive metal member electrically connected to the anode foil 2x. The cathode lead 2a is a conductive metal member electrically connected to the cathode foil 2y.

The element fixing tape 2t is based on a long film such as polypropylene or polyphenylene sulfide, and one side is an adhesive surface coated with acrylic adhesive, and the other side is a non-stick surface. It is an adhesive surface. The vertical width of the element fixing tape 2t is preferably at least 70% of the vertical width of the electrode foil and at most the vertical width of the separator 2z, more preferably at least the vertical width of the electrode foil and at most the vertical width of the separator 2z.

The capacitor element 2 is constructed by winding a cathode foil 2y to which a cathode lead 2a is attached and an anode foil 2x to which an anode lead 2b is attached, with a separator 2z interposed therebetween, and the outer periphery of the wound body thus formed. It is formed by fixing with an element fixing tape 2t, and then impregnating the wound body with a conductive polymer dispersion solution, drying it, and/or impregnating it with a driving electrolyte.

<Connection structure between electrode foil and lead>
Next, the connection between the anode foil 2x and the anode lead 2b and the connection between the cathode foil 2y and the cathode lead 2a will be explained. However, since these are the same, in the following, as shown in FIGS. 4(a) and 4(b), the anode foil 2x and the cathode foil 2y are used as the electrode foil 21, and the anode lead 2b and the cathode lead 2a are used as the leads 22. Give an explanation.

As shown in FIGS. 4A and 4B, the lead 22 is arranged on one surface of the electrode foil 21 in the thickness direction. Further, the lead 22 is drawn out from the electrode foil 21 toward one end in the electrode width direction. Further, the lead 22 and the electrode foil 21 are connected to each other at three connection parts 31 spaced apart in the electrode width direction. Note that the number of connecting parts 31 is not limited to three; the leads 22 and the electrode foil 21 may be connected at one connecting part 31, or they may be lined up at intervals in the electrode width direction. They may be connected at two or four or more connecting portions 31.

In each connection portion 31, caulking holes 21a and 22a are formed in the electrode foil 21 and the lead 22, respectively. Then, as will be described later, the burr 22b, which is a part of the lead 22, formed when the caulking hole 22a is formed passes through the caulking hole 21a (penetrating the electrode foil 21) and the electrode foil 21. The burr 22b protrudes to the other side in the thickness direction, and is pressed against the surface of the electrode foil 21 on the other side in the thickness direction. As a result, the electrode foil 21 is sandwiched between the lead 22 on one side in the thickness direction of the electrode foil 21 and the press-welded burr 22b, and the electrode foil 21 and the lead 22 are connected.

Further, four through holes 32 are formed in the electrode foil 21. Among the four through holes 32, two through holes 32 are arranged on one end side of the electrode foil 21 with respect to the connecting portion 31 closest to one end among the three connecting portions 31 in the electrode width direction. There is. These two through holes 32 are arranged one each at positions that are shifted from the leads 22 on both sides in the electrode length direction and do not overlap with the leads 22 in the thickness direction. Of the four through holes 32, the remaining two through holes 32 are arranged on the other end side of the electrode foil 21 with respect to the connecting part 31 closest to the other end among the three connecting parts 31 in the electrode width direction. ing. These two through holes 32 are arranged one by one at positions that are shifted from the leads 22 on both sides in the electrode length direction and do not overlap with the leads 22 in the thickness direction. By arranging the four through holes 32 in this way, the centers of the caulking holes 21a and 22a of the three connecting portions 31 are located at the center of each of the four through holes shown by the dashed line in FIG. 4(a). It is located within a rectangular region R having the center of 32 as its apex.

<How to fix the lead to the electrode foil>
Next, a method for connecting the lead 22 to the electrode foil 21 will be explained. When connecting the electrode foil 21 and the lead 22, first, as shown in FIG. ). The through holes 32 are formed in the electrode foil 21 using, for example, a cylindrical punch. Alternatively, the through holes 32 may be formed in the electrode foil 21 by laser processing or the like.

Subsequently, as shown in FIG. 5(b), the electrode foil 21 having four through holes 32 formed therein and the lead 22 are laminated and set in the caulking device 100. The crimping device 100 includes a lower die 101, an upper die 102, a crimping needle 103, and a press pin 104.

The lower mold 101 has a sliding hole 101a that extends in the vertical direction and is open at the upper end, and the press pin 104 is movable in the vertical direction along the sliding hole 101a. The press pin 104 is a member with a flat upper surface.

The upper mold 102 is arranged above the lower mold 101. A guide hole 102a extending in the vertical direction is formed in the upper die 102 at a portion vertically overlapping with the sliding hole 101a. The caulking needle 103 is movable in the vertical direction through the guide hole 102a. The caulking needle 103 has a tapered lower end.

In this embodiment, the laminate of the electrode foil 21 and the lead 22 is oriented so that the lead 22 is located above the electrode foil 21 (one side in the thickness direction is the upper side), and the lower mold 101 and the upper mold The laminated body of the electrode foil 21 and the lead 22 is set in the caulking device 100 so that the electrode foil 21 and the lead 22 are sandwiched between the electrode foil 21 and the lead 102 and vertically overlap the sliding hole 101a and the guide hole 102a.

Subsequently, as shown in FIG. 5(c), the caulking needle 103 is lowered along the guide hole 102a (the "burr forming step" of the present invention). Thereby, the caulking needle 103 penetrates the lead 22 and the electrode foil 21, thereby forming caulking holes 21a and 22a in the electrode foil 21 and the lead 22, respectively. Further, when the caulking hole 22a is formed in the lead 22, the lead 22 is inserted through the caulking hole 21a (through the electrode foil 21), and is placed below the electrode foil 21 (with the lead 22 of the electrode foil 21). A burr 22b extending to the opposite side is formed.

Subsequently, as shown in FIG. 5(d), the caulking needle 103 is raised and returned to the position before being lowered (the position shown in FIG. 5(b)), and the pressure welding pin 104 is raised (the "pressure welding step" of the present invention). . As a result, the burr 22b is pressed against the surface (the other surface) of the electrode foil 21 on the side opposite to the lead 22 on one side in the thickness direction by the pressure contact pin 104. Then, the electrode foil 21 is sandwiched between the lead 22 on one side in the thickness direction and the pressed burr 22b on the other side in the thickness direction, and the electrode foil 21 and the lead 22 are connected.

In addition, although the connection between the electrode foil 21 and the lead 22 in one of the three connection parts 31 has been described here, the connection between the electrode foil 21 and the lead 22 in one of the three connection parts 31 is also described in FIGS. 5(c) and 5. The same process as in (d) is performed to connect the electrode foil 21 and the lead 22.

<Effect>
When the burr 22b of the lead 22 is pressed against the other surface of the electrode foil 21 in the thickness direction, strain due to compressive stress is generated in the burr 22b, and the strain due to the compressive stress is transmitted to the electrode foil 21. When strain due to this compressive stress is transmitted to the electrode foil, there is a risk that cracks may occur at the ends of the electrode foil in the electrode width direction.

Furthermore, in this embodiment, the anode foil 2x and the cathode foil 2y have an oxide film of aluminum oxide formed on their surfaces, and aluminum oxide is relatively hard and brittle. Therefore, the anode foil 2x and the cathode foil 2y on which the aluminum oxide oxide film is formed are likely to crack when strain due to compressive stress is transmitted. Further, as described above, since the anode foil 2x has a relatively thick anodic oxide film formed on its surface, cracks are particularly likely to occur when strain due to compressive stress is transmitted.

In contrast, in the present embodiment, circular through holes 32 are formed in the electrode foil 21 at one end and the other end of the electrode foil 21 with respect to the connection portion 31 in the electrode width direction. There is. As a result, the strain caused by the compressive stress is absorbed in the through hole 32. As a result, cracks can be made less likely to occur at the ends of the electrode foil 21 in the electrode width direction.

Here, unlike this embodiment, by forming an elliptical through hole in the electrode foil, it is possible to make it difficult for cracks to occur at the ends of the electrode foil 21 in the electrode width direction, as described above. In this case, the ability of the through hole to absorb strain due to compressive stress mainly depends on the length of the ellipse in the short axis direction.

In this embodiment, a circular through hole 32 is formed in the electrode foil 21. As a result, if the through hole 32 is made circular with the same diameter as the length in the minor axis direction of the ellipse, it is possible to ensure the same compressive stress absorption performance as when the through hole is made elliptical, but the through hole is made into an ellipse. The through hole 32 can be made smaller than when the through hole 32 is made into a shape. Thereby, the area of the portion of the electrode foil 21 where the through hole 32 is not formed can be made as large as possible, and the capacitance of the electrolytic capacitor 1 can be ensured.

Further, in this embodiment, the through holes 32 are provided in the electrode foil 21 at one end and the other end of the electrode foil 21 with respect to the connection portion 31 in the electrode width direction. This makes it possible to make it difficult for cracks to occur at both ends of the electrode foil 21 in the electrode width direction.

Further, the strain due to the compressive stress generated at the connection portion 31 between the electrode foil 21 and the lead 22 propagates radially through the electrode foil 21, and the strain due to the compressive stress becomes larger in a portion closer to the connection portion 31. Therefore, if the distance between the through hole 32 and the connecting portion 31 is too short, the strain due to compressive stress in the portion of the electrode foil 21 where the through hole 32 is formed is large, and the strain due to the compressive stress cannot be sufficiently absorbed by the through hole 32. It may not be absorbed. In this embodiment, the through hole 32 is provided in a portion of the electrode foil 21 that is shifted from the connection portion with the lead 22 in the electrode length direction. As a result, the distance between the through hole 32 and the connecting portion 31 can be reduced compared to the case where the through hole 32 is provided in a portion of the electrode foil 21 that is located at the same position as the connecting portion 31 in the electrode length direction. It can be made longer. Thereby, the strain caused by the compressive stress can be sufficiently absorbed in the through hole 32. Furthermore, in this embodiment, the through hole 32 is provided at a position away from the portion where the electrode foil 21 and the lead 22 overlap. Thereby, the distance between the through hole 32 and the connecting portion 31 can be made longer than when the through hole 32 is provided in a portion where the electrode foil 21 and the connecting portion 31 overlap. Thereby, the strain caused by the compressive stress can be sufficiently absorbed in the through hole 32.

Furthermore, in this embodiment, the through holes 32 are provided in portions of the electrode foil 21 located on both sides of the connecting portion 31 in the electrode length direction (first direction). Thereby, the strain caused by the compressive stress transmitted to the electrode foil 21 on both sides of the connecting portion 31 in the electrode length direction can be absorbed by the through hole.

Examples of the present invention will be described below.

In Example 1, similarly to the above embodiment, by forming the through hole 32 in the electrode foil 21 and then connecting the electrode foil 21 and the lead 22, the bonded body of the electrode foil 21 and the lead 22 is I made one piece. Figure 6(a) shows one of these ten conjugates. In Comparative Example 1, ten joined bodies of the electrode foil 21 and the leads 22 were manufactured by connecting the electrode foil 21 and the leads 22 without forming the through holes 32 in the electrode foil 21. Figure 6(b) shows one of these ten conjugates.

In Example 1 and Comparative Example 1, the length of the electrode foil 21 in the electrode width direction was 12 mm, and the thickness of the electrode foil 21 (length in the direction perpendicular to the plane of the paper in FIG. 6) was 0.105 mm. Further, in Example 1 and Comparative Example 1, the length of the lead 22 in the electrode length direction was 2.2 mm, and the thickness of the lead 22 was 0.28 mm. In addition, in order to increase the effect of distortion, the pressure welding pin is raised so that the thickness of the crimped part (total of lead thickness after crimping, electrode foil thickness, and burr thickness) is 0.390 mm, which is thinner than the normal crimped part thickness. I adjusted the position.

In Example 1, the diameter of the through hole 32 was 0.45 mm, and the length between the end of the lead 22 and the center of the through hole 32 in the electrode length direction was 0.33 mm. Further, in Example 1, the length between the end of the electrode foil and the center of the through hole 32 was 1.55 mm in the electrode width direction. Further, in Example 1 and Comparative Example 1, the caulking holes 21a and 22a and the burr 22b were formed using a caulking needle having a diameter of 1.15 mm.

Table 1 shows the number of bonded bodies in which wrinkles S occurred in the electrode foil 21 and cracks C in the electrode foil 21 among the ten bonded bodies produced in Example 1 and Comparative Example 1, respectively. The number of zygotes obtained is shown.

As can be seen from the results in Table 1, in the case of Example 1, cracks C are less likely to occur in the electrode foil 21 than in the case of Comparative Example 1, that is, the bond between the electrode foil 21 and the lead 22 is It can be seen that the strength does not easily decrease.

In addition, in Example 1, the number of bonded bodies in which wrinkles S have occurred in the electrode foil 21 is greater than in Comparative Example 1, but when comparing FIG. 6(a) and FIG. In Example 1, the wrinkles S are strong wrinkles whose traces can be clearly discerned over the entire region of the electrode foil 21 between the connecting portion 31 and the end in the electrode width direction. The wrinkles S are so weak that traces can be discerned only in the area between the connection part 31 and the through-hole 32 in the area between the connection part 31 and the end in the electrode width direction of the electrode foil 21. It can be seen that wrinkles have occurred, the area where wrinkles S occur is small, and the traces are weak.

In Examples 2 to 5 and Comparative Example 2, the maximum displacement amount in the thickness direction that occurs in the electrode foil 21 when the burr 22b is displaced in the thickness direction in the laminated body of the electrode foil 21 and the lead 22 is calculated by numerical analysis. This is an analytical model for Displacing the burr 22b in the thickness direction corresponds to pressing the burr 22b against the electrode foil 21. The larger the maximum displacement amount in the thickness direction of the electrode foil 21, the greater the strain due to compressive stress in the electrode foil 21, indicating that cracks are more likely to occur in the electrode foil 21.

In Example 2, as shown in FIG. 7(a), among the four through holes 32 described in the above embodiment in the electrode foil 21, the upper side in the figure in the electrode width direction (lead extraction side) and the electrode length This is an example in which one through hole 32 on the left side in the figure in the horizontal direction is formed. In Example 3, as shown in FIG. 7(b), among the four through holes 32 described in the above embodiment in the electrode foil 21, the lower side in the figure in the electrode width direction (opposite side to the lead extraction direction), In addition, this is an example in which one through hole is formed on the left side in the figure in the electrode length direction. In Example 4, as shown in FIG. 7(c), out of the four through holes explained in the above embodiment in the electrode foil, two through holes on the left side in the figure in the electrode length direction (two on each side) are formed. This is an example of forming a . Example 5 is an example in which all four through holes 32 described in the above embodiments were formed in the electrode foil, as shown in FIG. 7(d). Comparative example 2 is an example in which no through hole 32 is formed in the electrode foil 21, as shown in FIG. 7(e).

In addition, in Examples 2 to 5 and Comparative Example 2, samples of the bonded bodies of the electrode foil 21 and the leads 22 that were actually produced were read using CT (Computed Tomography), and a CAD model for analysis was created from the CT data. did.

In the above sample, the length L1 of the lead 22 in the electrode length direction is 2.2 mm, and in the above samples of Examples 2 to 5 and Comparative Example 2, the left end of the electrode foil 21 in the electrode length direction in the figure is fixed. Then, a tensile stress of 5N was applied to the right end. Further, in the samples of Examples 2 to 5 and Comparative Example 2, the length W1 of the electrode foil 21 in the electrode width direction was 12 mm. In addition, in the samples of Examples 2 to 5 and Comparative Example 2, the thickness of the electrode foil 21 (length in the direction perpendicular to the paper surface of FIG. 7) was 0.105 mm, and the thickness of the lead 22 was 0.28 mm.

Further, in the samples of Examples 2 to 5, the diameter D of the through hole 32 is 0.45 mm, and the length W2 between the end of the electrode foil 21 and the center of the through hole 32 in the electrode length direction is 0. .33mm. Further, in the samples of Examples 2 to 5, the length L2 between the end of the lead 22 and the center of the through hole 32 in the electrode width direction was 0.33 mm. Further, in the samples of Examples 2 to 5, the caulking holes 21a and 22a were formed using a caulking needle having a diameter of 0.45 mm.

In Examples 2 to 5 and Comparative Example 2, the maximum amount of displacement in the thickness direction of the electrode foil was calculated when the burr 22b was displaced 0.02 mm toward the electrode foil 21 in the analytical model described above. Table 2 shows the maximum displacement amount in Examples 2 to 5 and Comparative Example 2, and the reduction rate of the maximum displacement amount in Examples 2 to 5 with respect to Comparative Example 2.

From the results in Table 2, in Examples 2 to 5 in which through-holes 32 were formed in electrode foil 21, the electrode foil 21 and leads 22 were bonded together, compared to Comparative Example 2 in which through-holes were not formed in electrode foil 21. It can be seen that the above maximum displacement amount is small, that is, cracks are less likely to occur in the electrode foil 21 when the electrode foil 21 and the lead 22 are joined.

<Modified example>
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made within the scope of the claims.

In the embodiment described above, in the electrode foil 21, in the electrode width direction, the lead 22 is located between the area where the three connection parts 31 are arranged and each of both ends of the electrode foil 21. Although the through holes 32 are formed in the portions located on both sides of the hole, the present invention is not limited thereto.

For example, of the four through holes 32 described above, only two through holes 32 located on one side of the lead 22 in the electrode length direction may be formed in the electrode foil 21. Furthermore, only one of these two through holes 32 may be formed in the electrode foil 21.

Alternatively, of the four through holes 32 described above, only two through holes 32 located at one end of the electrode foil 21 with respect to the connecting portion 31 may be formed in the electrode foil 21 in the electrode width direction. Furthermore, only one of these two through holes 32 may be formed in the electrode foil 21.

Furthermore, in the embodiment described above, the through hole 32 is located at a portion of the electrode foil 21 that is shifted from the connection portion 31 in the electrode length direction, and is located at a position away from the portion where the electrode foil 21 and the lead 22 overlap. However, it is not limited to this. For example, in the electrode width direction, the distance between the connection part 31 on the most one side and one end of the electrode foil 21 and the distance between the connection part 31 on the other side and the other end of the electrode foil 21 are sufficiently long, etc. When a sufficient distance between the connecting portion 31 and the through hole 32 can be secured, the through hole 32 is located at the same position in the electrode foil 21 as the connecting portion 31 in the electrode foil 21 in the electrode length direction. It may be formed in a portion overlapping with the lead 22 of.

Further, in the above-described embodiment, the through hole 32 is circular, but it is not limited to this. The through hole 32 may be elliptical, circular, or polygonal that approximates an ellipse.

1 Electrolytic capacitor 2a Cathode lead 2b Anode lead 2x Anode foil 2y Cathode foil 21 Electrode foil 22 Lead 22a Burr 32 Through hole

Claims (7)

an electrode foil extending in a first direction;
a lead disposed on one surface of the electrode foil in the thickness direction and drawn out from the electrode foil in a second direction perpendicular to both the first direction and the thickness direction;
The burr of the lead that protrudes through the electrode foil in the thickness direction is pressed against the surface of the electrode foil on the other side in the thickness direction, so that the electrode foil is sandwiched between the lead and the burr. the electrode foil and the lead are connected;
In the second direction of the electrode foil, a through hole is provided in an edge region of the electrode foil for a portion located between an end of the electrode foil and a connecting portion between the electrode foil and the lead. ,
An electrolytic capacitor characterized in that the diameter of the through hole is smaller than the diameter of a caulking hole formed through a region sandwiched between the lead and the burr of the electrode foil. The electrolytic capacitor according to claim 1, wherein the through hole is circular or oval. The through hole is located between both ends of the electrode foil in the second direction and between each of the ends of the electrode foil and the connecting portion between the electrode foil and the lead. 3. The electrolytic capacitor according to claim 1, wherein the electrolytic capacitor is provided on each side. 4. The electrolytic capacitor according to claim 1, wherein the through hole is provided in a portion of the electrode foil that is shifted in the first direction from a connection portion with the lead. 5. The electrolytic capacitor according to claim 4, wherein the through holes are provided in portions of the electrode foil located on both sides of the connection portion with the lead in the first direction. 6. The electrolytic capacitor according to claim 4, wherein the through hole is provided at a position away from a position where the electrode foil and the lead overlap. an electrode foil extending in a first direction;
A method for manufacturing an electrolytic capacitor, comprising: a lead disposed on one surface of the electrode foil in the thickness direction and drawn out from the electrode foil in a second direction perpendicular to both the first direction and the thickness direction. And,
The lead is placed on one side of the electrode foil in the thickness direction, and a crimping needle is inserted through the electrode foil and the lead from the one side in the thickness direction, so that the lead is crimped in the thickness direction. a burr forming step of forming a burr penetrating the electrode foil;
Pressing the burr to the other surface of the electrode foil in the thickness direction, sandwiching the electrode foil between the lead and the burr, and connecting the electrode foil and the lead. ,
moreover,
Before the pressure-welding step, a through hole is formed in an edge region of the electrode foil in a portion located between the electrode foil and the connection portion with the lead in the second direction of the electrode foil. A through-hole forming step,
A method for manufacturing an electrolytic capacitor, wherein the diameter of the through hole is smaller than the diameter of a caulking hole formed through a region of the electrode foil sandwiched between the lead and the burr.

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