capacitor

Abstract

To prevent cracks and breaks during a process of connecting a tab to an electrode foil that has been subjected to high-magnification surface enlargement and chemical conversion treatment, thereby improving the reliability of the capacitor.SOLUTION: A method for manufacturing a capacitor in which an electrode foil 2 and a terminal (tab) 4 are connected includes the steps of subjecting an electrode foil to a surface-expanding treatment, forming a plurality of divided sections 12 in the electrode foil that has been subjected to the surface-expanding treatment, forming an oxide film on the surfaces of the divided portions in the electrode foil with the plurality of divided portions formed, and arranging terminals on the electrode foil with the oxide film formed on the surfaces of the plurality of divided portions and performing a connection process, and the plurality of divided portions are formed at least in a connection portion with the terminal.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a terminal technology for electrode foils used in electrolytic capacitors and the like. [Background technology]

[0002] In capacitors such as electrolytic capacitors, terminals, which are separate components, are connected to the electrode foil. Techniques for connecting terminals to electrode foil include stitch connection and cold welding. In stitch connection, the flat portion of the terminal is placed on the electrode foil, a stitch needle is passed through the flat portion, and a raised piece on the terminal side that follows the needle's penetration is passed through the electrode foil. The raised piece is then shaped and pressed against the electrode foil, connecting the electrode foil and the terminal. Unlike other connection techniques, this technology is an excellent connection technique that uses the minimum number of components, namely, terminals and electrode foils, and the connection process also utilizes the formability and retention properties of the terminal material.

[0003] Regarding this stitch connection, it has been disclosed that an electrode foil and a plate-like terminal are overlapped and sandwiched together, a through-hole is formed in both, and a cut-and-raised piece on the terminal side that penetrates the electrode foil is molded on the electrode foil (for example, Patent Document 1).It is also known that a tab is overlapped on the electrode foil and placed in a lower mold, a stitch needle is passed from above the tab toward the electrode foil, and a push-up pin is pressed toward an upper mold against the cut-and-raised piece that penetrates from the tab into the electrode foil, thereby connecting the tab and the electrode foil (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 44-006110 [Patent Document 2] Japanese Patent Application Publication No. 7-106203 Summary of the Invention [Problem to be solved by the invention]

[0005] The electrode foils used in electrolytic capacitors are valve metal foils such as aluminum and copper. An etching layer, for example, is formed on the surface of this valve metal foil by a surface-expanding process, and a dielectric oxide film is then formed on top of this by a chemical conversion process. For example, in the case of aluminum electrode foils, the aluminum itself has excellent stretchability and flexibility, but the dielectric oxide film is hard, reducing the stretchability and flexibility of the electrode foil. In particular, in recent years, in order to meet the demand for higher capacity, smaller size, and lighter weight of electrolytic capacitors, electrode foils have been subjected to more extensive surface-expanding processes to increase the surface area. However, this also increases the area of the dielectric oxide film, resulting in the electrode foil becoming brittle and hard, and significantly reducing the flexibility of the material itself. In stitch connections, in which a terminal is placed on such an electrode foil and a stitch needle is passed through it, or in cold pressure welding, in which the electrode foil and the terminal are pressure-welded, stress acts on the electrode foil when the stitch needle passes through or when the terminal is pressure-welded, and this stress may cause cracks, breaks, etc. Damage such as cracks and breaks can be repaired by an aging treatment that includes another chemical conversion treatment, but repair treatments that assume breaks, etc., have the problem of requiring time and effort for the aging treatment.

[0006] Patent Documents 1 and 2 do not disclose or suggest anything about such a problem, and their configurations cannot solve such a problem.

[0007] In view of the above problems, an object of the present invention is to prevent cracks and breaks during the process of connecting tabs to electrode foil that has been subjected to high-magnification surface enlargement treatment and chemical conversion treatment, thereby improving the reliability of the capacitor. [Means for solving the problem]

[0008] In order to achieve the above object, one aspect of the capacitor of the present invention is a capacitor in which a surface-enlarged electrode foil and a terminal are connected, the surface-enlarged layer of the electrode foil being The cutting section has an oxide film formed on the surface. , at least the connection portion with the terminal In the part where , an oxide film was formed on the surface The aforementionedIt contains multiple disconnected parts. ,before a dielectric oxide film is formed on the surface-enlarging treatment layer and the inner surface of the dividing portion; Formed in the area excluding the connection Divided part of the electrode foil It is open in a rolled state.

[0009] The above condenser Sa Leave, The electrode foil has a plurality of the divided portions, leaving a foil core portion. That's fine.

[0010] The above condenser Sa Leave ,before Separated section is before Electrode foil Even if the groove width is 50μm or less, including 0, when the surface is flattened good.

[0011] The above condenser Sa Leave ,before Separated section are spaced apart with an average pitch of 2100 μm or less. good.

[0012] In the capacitor, the dividing portions may be provided at intervals with an average pitch of 220 μm or less. 。 [Effects of the Invention]

[0013] According to the present invention, any of the following effects can be obtained.

[0014] (1) The divided portions formed on the surface of the electrode foil can impart flexibility to the electrode foil with a high capacity, thereby suppressing the occurrence of cracks due to pressure and preventing the cracks from expanding.

[0015] (2) Furthermore, the formation of the dividing portion improves the formability of the electrode foil, thereby preventing damage to the electrode foil during the process of connecting the electrode foil and the tab, which includes folding the electrode foil and pressing the cut-out piece of the tab against the electrode foil.

[0016] (3) By improving the formability of the electrode foil, the core of the electrode foil can be made thinner, enabling the capacitor to have a higher capacity.

[0017] (4) By suppressing damage to the electrode foil, the reliability of the electrode foil and the capacitor can be improved. [Brief explanation of the drawings]

[0018] [Figure 1] 3A and 3B are diagrams showing an example of a connection state between an electrode foil and a terminal component according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the surface state of an electrode foil. [Figure 3] FIG. 10 is a diagram illustrating an example of stitch connection processing. [Figure 4] 10 is a diagram showing an example of a position where a dividing portion is formed in an electrode foil according to a second embodiment. FIG. [Figure 5] FIG. 10 is a diagram showing a comparative example in which cracks occur due to stitch connection. [Figure 6] 10A and 10B are diagrams showing experimental examples illustrating the flexibility of an electrode foil due to the formation of divided portions. DETAILED DESCRIPTION OF THE INVENTION

[0019] First Embodiment

[0020] A first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 shows an example of a connection state between an electrode foil and a terminal component according to the first embodiment. The configuration shown in Fig. 1 is an example, and the present invention is not limited to the configuration.

[0021] In this capacitor, as shown in FIG. 1, a tab 4, which is a terminal component, is overlapped on the flat surface of electrode foil 2, and a stitch connection 6 that connects electrode foil 2 and tab 4 is formed in part of the overlapping portion. This electrode foil 2 is, for example, primarily the anode side electrode foil, and a highly etched layer 16 (B in FIG. 2) is formed on the surface side of the electrode foil. Electrode foil 2 is formed, for example, in the shape of a horizontally elongated strip. A separator (not shown) is then interposed between the anode side and cathode side electrode foil, and the foils are wound or overlapped to form a capacitor element.

[0022] The electrode foil 2 is also surface-treated at least in the area where the stitch connection 6 is formed. The surface-treated electrode foil 2 has a plurality of dividing portions 12 (FIG. 2) in the etching layer 16 formed on the surface.

[0023] The tab 4 connected to the electrode foil 2 has, for example, a flat portion and a lead portion that are placed on the flat surface of the electrode foil 2. The flat portion of the tab 4 is a flat portion formed by compressing an aluminum rod into a flat shape. The lead portion is formed, for example, by a wire plated with a solderable metal surface.

[0024] At the stitch connection portion 6, for example, an opening 8 is formed by a stitch needle 30 (FIG. 3) penetrating the flat portion of the electrode foil 2 and the tab 4, and a cut-and-raised piece 10 of the tab 4 that has been inserted into the electrode foil 2 through the opening 8 is disposed on the back side of the electrode foil 2. This cut-and-raised piece 10 is folded back onto the flat surface of the electrode foil 2 on the insertion side. This causes the electrode foil 2 and the tab 4 to be integrated.

[0025] <Surface processing of electrode foil 2>

[0026] Fig. 2 shows an example of the surface state of the electrode foil. The surface state shown in Fig. 2 is just an example.

[0027] 2A, linear dividing portions 12 are formed in electrode foil 2 along the short side direction of electrode foil 2. The length and the intervals between dividing portions 12 may be set arbitrarily, or the linear direction may be determined depending on the method for forming them. The direction in which dividing portions 12 are formed may be along the long side direction of electrode foil 2, in the long side direction of electrode foil 2, or obliquely.

[0028] As shown in Fig. 2B, the electrode foil 2 has a core 14 of a predetermined thickness formed at the center in the thickness direction, and etching layers 16 that have been subjected to a surface-enlarging process on both ends of the core 14. The dividing portions 12 are formed in the etching layer 16 of the electrode foil 2. The electrode foil 2 has a dielectric oxide film 18 formed on the surfaces of the etching layer 16 and the dividing portions 12. The thickness of the core 14 is, for example, 20 to 60 μm, and the thickness of the etching layer 16 on both sides may be in the range of 40 to 200 μm.

[0029] The dividing portions 12 are formed, for example, by dividing the etching layer 16 at a predetermined depth from the surface of the electrode foil 2 toward the core 14. The depth of the dividing portions 12 may be set so as not to divide the core 14, and may be, for example, approximately the same as the depth of the etching layer 16 in the thickness direction of the electrode foil 2. It is not necessary for all dividing portions 12 to have a uniform depth. The dividing portions 12 may be formed, for example, by cracking the etching layer 16 in the thickness direction, or by using a predetermined jig to tear, cut, notch, or carve the surface of the electrode foil. Cracks may also be formed by applying a predetermined amount of pressure or tension to the surface of the electrode foil 2 that has been subjected to a surface-enlarging treatment or a chemical conversion treatment.

[0030] The opening width of the dividing portions 12 may be formed so that it is 0 to 50 μm or less when the electrode foil 2 is flattened. The dividing portions 12 may not necessarily be formed in the etching layer 16 on both sides of the electrode foil 2, but may be formed only on the side of the electrode foil 2 that is subjected to deformation or pressure in the winding direction or during stitching. The dividing portions 12 are formed by forming multiple cuts, giving the surface of the electrode foil 2 a so-called bellows shape. The position, range, number, and spacing of the dividing portions 12 may be determined depending on, for example, the magnitude of the bending stress due to the pressure or deformation applied to the electrode foil 2. The spacing between adjacent dividing portions 12 may be, for example, an average pitch of 220 μm.

[0031] When a pressure force F1 is applied to the surface of the electrode foil 2 with the dividing portions 12 formed in this manner, as shown in FIG. 2C, the electrode foil 2 is flexible and deforms without cracking. The force F2 acting on the electrode foil surface due to the pressure force F1 is dispersed to the slits of the dividing portions 12 formed, for example, at a position close to the pressure position. In other words, the dividing portions 12 can prevent the force F2 from reaching the end surface of the electrode foil through the surface. This prevents the electrode foil 2 from developing large cracks from the pressed portion toward the foil end when pressure is applied.

[0032] <Capacitor manufacturing process>

[0033] Next, an example of a capacitor manufacturing process is shown. Fig. 3 shows an example of a stitch connection process. The process shown in Fig. 3 is an example of a capacitor manufacturing method of the present disclosure. Note that the process procedure, process steps, and jigs used in the connection process shown in Fig. 3 are merely examples, and are not limited to the configuration to which the present invention relates.

[0034] The manufacturing process for this capacitor includes, for example, a process for forming electrode foil 2, which includes forming dividing portions 12 in the anode foil, and a process for connecting tabs 4 to electrode foil 2. The process for forming electrode foil 2 includes, for example, a process for shaping aluminum foil, a process for forming etching layer 16 on the anode-side surface by surface-enlarging treatment, and a process for forming a dielectric oxide film by chemical conversion treatment. After dividing portions 12 are formed in predetermined positions on the surface of electrode foil 2, an aging process may be performed to form dielectric oxide film 18 on the surface of dividing portions 12.

[0035] In the process of connecting the electrode foil 2 and the tab 4, for example, as shown in A of Fig. 3, the tab 4 is placed as a terminal part on the upper surface of the electrode foil 2. The electrode foil 2 and the tab 4 are placed on a lower mold 20 as an example of a first mold, and an upper mold 22 as an example of a second mold is placed on the upper surface of the tab 4. In other words, the electrode foil 2 and the tab 4 are sandwiched and held between the lower mold 20 and the upper mold 22.

[0036] The lower mold 20 and the upper mold 22 are formed with through-holes 24, 26, respectively. A stitching needle 30 is disposed in the center of the through-hole 26 of the upper mold 22. The stitching needle 30 has, for example, a cylindrical shaft 32 and an acute-angled pyramidal tip 34.

[0037] At this time, the electrode foil 2 is positioned such that the formation range 36 of the dividing portion 12 is aligned with, for example, the punching position of the stitch needle 30. This formation range 36 is an example of the range of the stitch connection portion 6 described above, and may be set so as to include the range in which the cut-and-raised piece 10 of the tab 4 is folded back, with the punching position of the stitch needle 30 as the center.

[0038] In the piercing step with stitch needle 30, as shown in B of Fig. 3, electrode foil 2 and tab 4 are held between lower mold 20 and upper mold 22, and stitch needle 30 is inserted through electrode foil 2 and tab 4 from the tab 4 side. This insertion creates cut-and-raised piece 10 in tab 4 cut by tip 34 of stitch needle 30, and cut-and-raised piece 38 in electrode foil 2. At this time, cut-and-raised piece 10 is inserted into the electrode foil 2 side together with stitch needle 30.

[0039] After forming the cut-and-raised piece 10 on the back side of the electrode foil 2 with the stitching needle 30, the stitching needle 30 is retracted. After the stitching needle 30 is retracted, a forming die 40 is placed below the electrode foil 2. A pressing surface 42 is formed on the forming die 40. This pressing surface 42 is brought into contact with the cut-and-raised piece 10, and pressing is performed between the forming die 40 and the upper die 22, thereby forming the cut-and-raised piece 10 of the tab 4 on the back side of the electrode foil 2.

[0040] 3D, cut-and-raised pieces 10, 38 are pressed against the back surface of electrode foil 2 to connect to electrode foil 2. This forms folded connection portions 44 that tightly attach tab 4 to electrode foil 2. If each corner of pressing surface portion 42 of forming die 40 is curved, for example, the cut-and-raised pieces 10, 38 of electrode foil 2 and tab 4 will not be damaged, and the quality of pressure welding forming will be improved.

[0041] After this stitching process, an aging process may be performed to form a dielectric oxide film 18 on the surface of the divided portion 12 .

[0042] During this stitch connection process, the electrode foil 2 is subjected to pressure from, for example, the tab 4 deformed by the perforation by the stitch needle 30, and pressure FB from the pressing of the forming die 40. The dividing portion 12 of the electrode foil 2 disperses the applied pressure in the forming region 36 including the stitch connection portion 6 or in the surrounding area, preventing the pressure from propagating to the end face side of the electrode foil 2.

[0043] <Advantages of the First Embodiment>

[0044] (1) The dividing portions 12 formed on the surface of the electrode foil 2 can impart flexibility to the electrode foil with a high capacity, suppressing the occurrence of cracks due to pressure and preventing the cracks from expanding.

[0045] (2) Furthermore, the formation of the dividing portion 12 improves the formability of the electrode foil 2, thereby preventing damage to the electrode foil 2 during the connection process of the tab 4, which includes folding back the electrode foil 2 and pressing the cut-up pieces 10, 38 of the electrode foil 2 and the tab 4 against the electrode foil 2.

[0046] (3) By improving the formability of the electrode foil 2, the core portion 14 of the electrode foil 2 can be made thinner, and the capacitance of the capacitor can be increased.

[0047] (4) By suppressing damage to the electrode foil 2, the reliability of the electrode foil 2 and the capacitor can be improved.

[0048] (5) By providing flexibility to the electrode foil 2, the processing accuracy of the electrode foil 2 can be improved and the probability of producing non-conforming products can be reduced.

[0049] (6) It becomes easier to adjust the force applied during the punching process and folding process in stitch connection.

[0050] (7) The reduction in the rate of damage to the electrode foil 2 allows for faster processing and product checks.

[0051] (8) By preventing damage to the electrode foil 2 due to the connection of the tabs, the aging treatment after processing can be omitted or can be performed with only a light treatment, thereby speeding up the capacitor manufacturing process.

[0052] Second Embodiment

[0053] FIG. 4 shows an example of the positions where the dividing portions of the electrode foil according to the second embodiment are formed.

[0054] In this embodiment, the positions at which dividing portions 12 are formed on electrode foil 2 will be described.

[0055] The dividing portion 12 disperses pressure FB applied to the electrode foil 2 due to the perforation by the stitch needles 30 and the folding process of the cut-and-raised pieces 10, 38 that form the folded-back connection portion 44. To achieve this pressure dispersion function, the electrode foil 2 may have dividing portion 12 formed over the entire stitch connection portion 6, or may have dividing portion 12 formed over a partial range thereof.

[0056] 4A, the electrode foil 2 may have a dividing portion 12 formed in at least an area 50 where the cut-and-raised piece 10 of the tab 4 abuts when the folded-back connection portion 44 is formed. In this case, the area where the dividing portion 12 is formed may be determined, for example, before the stitch connection process is performed, taking into account the width of the opening formed by the stitch needle 30 and the length of the cut-and-raised piece 10 formed by the stitch needle 30. The electrode foil 2 may have divided portions 12 formed in the portions where the stitch needles 30 are to be pierced, or the divided portions 12 may be formed to avoid such piercing portions.

[0057] By forming a dividing section 12 in the range 50 of this electrode foil 2, when the forming die 40 is pressed, the electrode foil 2 releases the applied pressure FB at the contact portion with the cut-and-raised piece 10, and does not transmit the pressure to the surrounding area of the electrode foil 2.

[0058] 4B, the electrode foil 2 may have a dividing portion 12 formed in at least a range 52 that does not come into contact with the cut-and-raised piece 10 of the tab 4 when the folded-back connection portion 44 is formed. In this range 52, the dividing portion 12 may be formed so as to surround the abutting portion of the cut-and-raised piece 10, for example.

[0059] By forming the dividing section 12 in this manner in the range 52 of the electrode foil 2, stresses received by the electrode foil 2, for example, by the perforation process of the stitch needle 30 or the folding back of the cut-and-raised piece 10, are released from the electrode foil 2 on the outer edge side within the stitch connection section 6, and are not propagated to the surroundings of the electrode foil 2.

[0060] <Advantages of the second embodiment>

[0061] According to this configuration, in addition to the effects shown in the above embodiment, the following effects can be obtained.

[0062] (1) The area in which the dividing portion 12 is formed can be reduced, thereby reducing the processing load.

[0063] (2) The bending stress and stitch needle 30 stress transmitted from the contact portion with the tab 4 can be separated, and the stress can be prevented from reaching the end face of the electrode foil 2.

[0064] Comparative Example

[0065] FIG. 5 shows a comparative example in which a stitch connection process is performed on a high-capacity electrode foil.

[0066] As previously mentioned, the high-capacity electrode foil 60 becomes brittle and hardened due to the surface-expanding and chemical conversion treatments, significantly reducing the inherent flexibility of the material. Therefore, when a tab 4 is placed on such an electrode foil 60 and stitch-connected, some or all of the stress FX applied to the electrode foil 60 by the stitch needle piercing process and the folding back process of the cut-and-raised piece 10 propagates around the stitch connection 6, as shown in FIG. 5 . The stress FX is then released from the foil edge near the stitch connection 6. Because the cross-section of this foil edge is weaker than the foil surface, the electrode foil 60 is prone to cracking or separation, for example, toward the stitch connection 6, potentially forming a large crack 62. Such cracks 62 can lead to, for example, a decrease in the capacitance of the capacitor and an increase in the equivalent series resistance (ESR), thereby degrading the capacitor's performance.

[0067] In contrast, by forming a separation section 12 at least in the stitch connection section 6 as in the present invention, the stress applied by the stitch connection is released to the outside, and excessive force is not applied to the foil end section, thereby suppressing the occurrence of cracks.

[0068] [Experimental Example 1]

[0069] Next, we will explain the flexibility of the electrode foil 2 due to the formation of the dividing portions 12. The Erichsen value is used as an index of the flexibility of this electrode foil 2. Electrode foils 2 with average pitches of dividing portions 12 set to 70 μm, 220 μm, 950 μm, 2100 μm, and 3100 μm were prepared, along with an electrode foil without dividing portions as a comparative example. An Erichsen test was performed on each electrode foil. In the Erichsen test, each electrode foil 2 and the electrode foil without dividing portions were clamped at 10 kN using a die with an inner diameter of 33 mm and a blank holder, and pressed with a chisel-shaped punch. The chisel-shaped punch was 30 mm wide and had a spherical tip with a cross-sectional diameter of 4 mm. The chisel portion of the punch was pressed along the short side of the electrode foil. The punch pressing speed was 0.5 mm / min.

[0070] The results of this Erichsen test are shown in Figure 6. Figure 6 is a graph with the horizontal axis representing the average pitch of the dividing portions 12 and the vertical axis representing the Erichsen value. As shown in Figure 6, the Erichsen value of the comparative example was 1.4 mm, while the Erichsen value of the electrode foil 2 in which the average pitch of the dividing portions 12 was set to 3100 μm was 1.5 mm. This shows that providing dividing portions 12 distributes the bending stress during winding, thereby imparting flexibility to the electrode foil 2.

[0071] Furthermore, when the average pitch of the dividing portions 12 was 2100 μm or less, the Erichsen value was 1.7 mm or more, which was a clear difference compared to the comparative example in which the dividing portions 12 were not formed. In other words, it can be seen that providing dividing portions 12 at an average pitch of 2100 μm or less effectively distributes the bending stress during winding, and provides the electrode foil 2 with good flexibility.

[0072] In particular, when the average pitch of the dividing portions 12 was 950 μm or less, the Erichsen value was 2.0 mm or more, which was a dramatically better result than the comparative example in which the dividing portions 12 were not formed. In other words, it can be seen that by providing the dividing portions 12 at an average pitch of 950 μm or less, the bending stress during winding is dispersed extremely well, and extremely good flexibility is imparted to the electrode foil 2.

[0073] [Experimental Example 2]

[0074] Next, an experimental example will be shown in which a tab is stitch-connected to an electrode foil having a divided portion formed therein. In this experimental example, 10 pieces of electrode foil were stitch-connected, one with dividing portions 12 formed on the entire surface of the electrode foil, and the other with no dividing portions formed. Then, the state of cracks that had occurred between the stitch-connected portions was checked from the end face side of each electrode foil. The electrode foils used are similar except for the presence or absence of the dividing portion. The results of the experimental examples are shown in Table 1 below.

[0075] [Table 1]

[0076] As a result of this experiment, by forming the dividing portion 12 in the electrode foil, the number of pieces without cracks due to the stitch connection increased significantly from 1 to 7. In addition, the number of pieces with some cracks that did not reach the stitch connection 6 decreased. Furthermore, by forming the dividing portion 12 in the electrode foil 2, no cracks occurred up to the stitch connection 6. In other words, by forming the dividing portion 12, the number of pieces with cracks due to the stitch connection process decreased from 9 to 3. The electrode foil 2 on which the tab 4 is installed can be either crack-free or cracked but not reaching the stitch connection 6. If the crack does not reach the stitch connection 6, it does not affect the strength of the connection of the tab 4. However, if the crack reaches the stitch connection 6, it cannot be used because it will affect the connection.

[0077] The above results show that using electrode foil 2 with dividing portion 12 can significantly reduce the impact of stitch connection on electrode foil 2. Furthermore, forming dividing portion 12 eliminates or reduces the need for repair of electrode foil 2 after stitch connection, and can also reduce the number of electrode foils 2 that become unusable due to cracks.

[0078] Other Embodiments

[0079] Modifications of the above-described embodiment are listed below.

[0080] (1) In the above embodiment, multiple dividing portions 12 are formed at least in the portion of the electrode foil 2 where the stitch connection 6 is formed. However, this is not limited to this. The dividing portions 12 may be provided at the end of the electrode foil 2, at least near the connection of the tab 4. This disperses stress from the stitch connection 6 toward the foil end of the electrode foil 2, thereby suppressing cracks between the stitch connection 6 and the foil end of the electrode foil. In particular, as capacitors become smaller, the distance between the stitch connection 6 and the foil end of the electrode foil becomes shorter, making stress dispersion more difficult. However, by providing flexibility to this portion through the formation of dividing portions 12, stress dispersion can be promoted and cracks can be suppressed. Alternatively, dividing portions 12 may be formed over the entire surface of the electrode foil. By providing flexibility to the entire electrode foil, not just the vicinity of the stitch connection 6, stress generated during connection can be more easily dispersed, which is expected to further suppress cracks.

[0081] (2) In the above embodiment, dividing portion 12 formed on the surface of electrode foil 2 is not limited to a linear shape or a linear shape having a bent portion. Dividing portion 12 may be, for example, a curved shape or a shape formed by intersecting multiple lines.

[0082] (3) In the above embodiment, dividing portion 12 is formed on both the front and back sides of electrode foil 2, but this is not limiting. Electrode foil 2 may have dividing portion 12 on only one of the front and back sides, for example.

[0083] (4) In the above embodiment, dividing portions 12 are formed on both the front and back surfaces of electrode foil 2, and dividing portions 12 are formed at positions facing each other across core portion 14 of electrode foil 2. However, this is not limiting. Dividing portions 12 may be formed at different positions on the front and back surfaces, for example.

[0084] (5) In the above embodiment, the electrode foil 2 is opened together with the tab 4 by the stitch needle 30 during the stitch connection process. However, this is not limited to this. For example, a through-hole may be opened in the electrode foil 2 at the position where the predetermined dividing portion 12 is formed before connection to the tab 4. Then, during the stitch connection process, the tab 4 may be positioned in accordance with the through-hole position, and the stitch needle 30 may be pierced. This prevents pressure due to deformation of the tab 4 from being applied when the stitch needle 30 pierces the hole. Furthermore, the dividing portion 12 of the electrode foil 2 only needs to be able to withstand pressure from the cut-and-raised piece 10 of the tab 4. For example, the dividing portion 12 can be formed on only one side of the electrode foil 2. Furthermore, by forming a through-hole in advance in the electrode foil 2, it is possible to prevent the occurrence of so-called "waviness," in which a portion of the foil is deformed when the stitch needle 30 is inserted.

[0085] (6) Furthermore, multiple dividing portions 12 may be formed radially from the punching position of stitch needle 30. By forming them in this manner, compressive stress caused by pressure application during punching can be absorbed, and cracking of electrode foil 2 can be prevented.

[0086] (7) In the above embodiment, the connection between the tab 4 and the electrode foil 2 is described as being a stitch connection, but cold pressure welding or ultrasonic welding may also be used. In cold pressure welding or ultrasonic welding, pressure is applied to the tab placed on the electrode foil from the tab direction, and the formation of the dividing portion 12 distributes the stress during pressure, preventing cracking of the electrode foil.

[0087] (8) In the above embodiment, the connection between the tab and the electrode foil is illustrated, but this connection can be applied to the connection between the tab and the electrode foil of various capacitors such as electrolytic capacitors and electric double layer capacitors.

[0088] (9) In the above embodiment, the perforation process of the stitch needle 30 and the folding back process of the cut-and-raised piece 10 are performed in a single flow, and the lower mold 20 and upper mold 22 that support the electrode foil 2 and the tab 4 are used in these processes. However, this is not limited to this. Different molds may be used for the perforation process and the folding back process, or a process for releasing the electrode foil 2 and the tab 4 from the mold may be interposed between these processes. This configuration can eliminate wrinkles and waves that occur in the electrode foil 2 due to pressing, and prevent damage to the electrode foil 2.

[0089] (10) In the above embodiment, the connection between the tab 4 and the electrode foil 2 is described, but it goes without saying that the manufacturing method of the capacitor includes other steps such as a step of winding the electrode foil and a step of sealing it in an outer case.

[0090] As explained above, the most preferred embodiment of the present invention has been described, but the present invention is not limited to the above description, and it goes without saying that various modifications and changes can be made by those skilled in the art based on the gist of the invention as described in the claims or disclosed in the specification, and such modifications and changes are included in the scope of the present invention. [Industrial Applicability]

[0091] The condensate of the present invention Sa Therefore, the stress applied to the electrode foil during the process of connecting the tab to the electrode foil is released to the outside by the dividing portion formed in the electrode foil, which is useful in preventing damage to the electrode foil, which has hardened and become weak due to increased capacity. [Explanation of symbols]

[0092] 2, 60 electrode foil 4 Tabs 6 Stitch connection 8 Openings 10, 38 Cut-out pieces 12 Divided section 14 Core 16 Etching layer 18 Dielectric oxide film 20 Lower mold 22 Upper mold 24, 26 Through-hole section 30 stitch needles 32 Shaft 34 Tip 36 Formation Range 40 mold 42 Pressing surface 44 Folded connection 50, 52 range 62 Crack

Claims

1. A capacitor in which a surface-enlarged electrode foil and a terminal are connected, A capacitor characterized in that the electrode foil has a divided portion with an oxide film formed on its surface relative to the surface-expanding treatment layer, and the divided portion with an oxide film formed on its surface is included in at least the portion where the connection portion with the terminal is formed, and a dielectric oxide film is formed on the inner surfaces of the surface-expanding treatment layer and the divided portion, and the divided portion formed in the portion excluding the connection portion is open when the electrode foil is wound.

2. 2. The capacitor according to claim 1, wherein the electrode foil has a plurality of the divided portions, leaving a foil core portion.

3. the dividing portion has a groove width of 50 μm or less, including 0 μm, when the electrode foil is flattened; The capacitor according to claim 1 or 2,

4. the dividing portions are provided at intervals with an average pitch of 2100 μm or less; 4. The capacitor according to claim 1, wherein

5. the dividing portions are provided at intervals with an average pitch of 220 μm or less; 4. The capacitor according to claim 1, wherein

Images