Capacitor and method for manufacturing the same

Abstract

The objective is to provide a capacitor and a method for manufacturing the same, which provides a durable and reliable connection using the cold pressure welding method for connecting an electrode foil having an expanded surface layer with a divided section to a lead terminal. [Means for solving the problem] A capacitor comprising an electrode foil 510 having an expanded surface layer 515 with a divided portion 516, and a connection portion where the electrode foil 510 and a terminal are connected by a cold pressure welding method, wherein the connection portion has a shape having a short side and a long side in plan view, with the short side being in the width direction of the electrode foil 510, and preferably the divided portion 516 is a linear shape extending in the width direction of the electrode foil 510, more preferably the long side of the connection portion is perpendicular to the divided portion 516, and more preferably the Erichsen value of the electrode foil 510 is 6.53 N / mm 2 Let the following be the capacitor.

Description

Technical Field

[0001] The present invention relates to a capacitor with reduced foil cracking of an electrode foil and a method for manufacturing the same.

Background Art

[0002] In order to improve the capacitance of a capacitor, a device for expanding the surface area of an electrode foil has been realized. Specifically, a method for expanding the surface area of an anode foil is known as described below.

[0003] For example, an anode foil forms an etched layer obtained by performing an etching treatment on its surface, a deposited body layer obtained by depositing a powder of a valve-acting metal on the surface of a rolled foil, or a sintered body layer obtained by sintering a powder layer formed by applying and drying a powder of a valve-acting metal on the surface of a rolled foil. By doing so, the surface is expanded.

[0004] That is, the anode foil may be either a powder laminated foil having a powder layer in which powders of a valve-acting metal are aggregated as an expanded layer or an etched foil obtained by etching the surface of a stretched foil. The expanded layer can be composed of tunnel-shaped pits, sponge-shaped pits, or voids between densely packed powders.

[0005] The tunnel-shaped etching pits are holes dug in the foil thickness direction, which are typically formed by flowing a direct current in an acidic aqueous solution containing halogen ions such as hydrochloric acid. Further, the tunnel-shaped etching pits can be expanded in diameter by flowing a direct current in an acidic aqueous solution such as nitric acid.

[0006] In addition, the sponge-shaped etching pits form a sponge-shaped layer in which fine voids are connected and spread, which is formed by flowing an alternating current in an acidic aqueous solution containing halogen ions such as hydrochloric acid.

[0007] Furthermore, the powder is a powder of the same or different valve metal as the foil, and is formed by methods such as grinding, atomization, melt spinning, rotating disc method, or rotating electrode method. The atomization method can be water atomization, gas atomization, or water-gas atomization. If the powder layer is formed by sintering, it can be made by pasteuring with a binder or solvent, applying it to the foil and drying it, and then heating and sintering it in a vacuum or reducing atmosphere.

[0008] When forming a powder layer by vapor deposition, this powder layer can be produced, for example, by resistance heating vapor deposition or electron beam heating vapor deposition. This vapor deposition powder layer can be formed by heating the same or different valve metal as the foil body with resistance heat or electron beam energy to evaporate it, and depositing the vapor of the valve metal particles onto the surface of the foil body.

[0009] A dielectric film is formed on the surface of the enlarged anode foil by chemical conversion treatment. The dielectric film is hard, reducing the stretchability and flexibility of the anode foil. In particular, when the enlarged layer is made denser and its surface area increased (roughened, etc.) by enlarging the anode foil as described above in order to improve the capacitance of the capacitor, the proportion of the dielectric film on the anode foil increases, raising concerns that the flexibility and pliability will be further impaired. Patent Document 1 below discloses a technical concept for stress distribution measures, in which a divided section is provided in the width direction of the anode foil (short direction perpendicular to the length direction) approximately parallel to the length direction (long side direction) as a measure to suppress the occurrence of foil cracks and fissures due to the decrease in the flexibility of the anode foil. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] International release WO2017 / 171028 [Overview of the project] [Problems that the invention aims to solve]

[0011] In recent years, the demand for higher capacitance in capacitors has increased. Consequently, the surface area of ​​the dielectric film has also expanded, resulting in increased brittleness and hardening of the electrode foil, and a drastic reduction in the flexibility of the material itself. Therefore, even when electrode foil (typically anode foil) with an expanded surface layer having the aforementioned divided sections is used, and the connection between the lead terminal and the electrode foil is secured by cold welding (CW), there is a high possibility that stress on the terminal may cause foil cracking or fissures in the electrode foil.

[0012] Through diligent research by the inventors, it is becoming clear that the relative relationship between the divided portion and the cold welding die used during cold welding is deeply related to such foil cracking and fissures. The present invention has been made in view of the above-mentioned problems, and aims to provide a capacitor and a method for manufacturing the same, which have a durable and reliable connection portion when connecting an electrode foil having an expanded surface layer with a divided portion and a lead terminal using a cold welding method. [Means for solving the problem]

[0013] The present invention relates to a capacitor comprising an electrode foil having an expanded surface layer with a divided portion, and a connection portion in which the electrode foil and lead terminals are connected by a cold pressure welding method, wherein the divided portion is formed in the width direction of the electrode foil, and the connection portion has a shape having a short side and a long side in a plan view, with the short side being arranged in the width direction of the electrode foil.

[0014] Furthermore, the capacitor of the present invention is more preferably characterized in that the longer side of the connection portion is perpendicular to the direction of the division portion.

[0015] Furthermore, the capacitor of the present invention more preferably has an Erichsen value of 6.53 N / mm² for the electrode foil. 2 The following characteristics apply:

[0016] The method for manufacturing a capacitor of the present invention includes a step of providing a dividing portion in the width direction of an electrode foil in the enlarged surface layer of the electrode foil having an enlarged surface layer, and a step of connecting the electrode foil and the lead-out terminal by a cold pressure welding method using a cold pressure welding die. The cold pressure welding die includes a pressing portion having a shape with a short side and a long side in a plan view, and cold pressure welding is performed by arranging the short side of the pressing portion in the width direction of the electrode foil.

[0017] The method for manufacturing a capacitor of the present invention is more preferably characterized in that the long side of the connecting portion is in a direction orthogonal to the dividing portion.

[0018] The method for manufacturing a capacitor of the present invention is more preferably characterized in that the Erichsen value of the electrode foil is 6.53 N / mm 2 as follows.

Effects of the Invention

[0019] It is possible to provide a capacitor having a connection portion with highly durable and reliable terminal attachment by a cold pressure welding method using an electrode foil provided with an enlarged surface layer provided with a dividing portion, and a method for manufacturing the same.

Brief Description of the Drawings

[0020] [Figure 1] It is a diagram for explaining a dividing portion provided in advance in the enlarged surface layer of an electrode foil. [Figure 2] It is a conceptual diagram showing an example of a pressing portion of a cold pressure welding die. (a) is a conceptual diagram in a plan view of the pressing portion contacting the connection target portion of the cold pressure welding die, (b) is a conceptual diagram in a front view of the pressing portion observed from the A direction in FIG. 2(a), and (c) is a conceptual diagram in a left side view of the pressing portion observed from the B direction in FIG. 2(a). [Figure 3] It is an enlarged photograph of an anodic foil with foil cracking caused by the pressing of the pressing portion of the cold pressure welding die. [Figure 4] It is a diagram for explaining the preconditions and experimental results of an experiment for confirming the effects of the present invention. [Figure 5] It is a diagram showing an example of a connection portion between an anodic foil and a lead-out terminal of a capacitor according to an embodiment. <00​[Modes for carrying out the invention]

[0021] [Anode foil] The anode foil 510 shown in Figure 1(a) constitutes the anode electrode of the capacitor. The anode foil 510 is a valve-acting metal foil, such as tantalum foil or aluminum foil, and is, for example, a strip-shaped foil. The anode foil 510 has a surface expansion layer 515 on the surface of the core metal portion 514 (base material). As an anode foil 510 with a surface expansion layer 515 formed thereon, there is an etched foil in which the surface of the metal foil has been etched, a foil in which a vapor-deposited body is formed by depositing valve-acting metal powder onto the surface of the metal foil, or a powder laminated foil in which a sintered body is formed on the surface by coating and drying valve-acting metal powder onto the surface of the metal foil and sintering the resulting powder layer. That is, the surface expansion layer 515 consists of tunnel-shaped pits, sponge-like pits, or voids between densely packed powder particles.

[0022] Furthermore, tunnel-shaped etching pits are holes carved in the thickness direction of the metal foil. These tunnel-shaped etching pits are typically formed by passing a direct current through the metal foil in an acidic aqueous solution containing halogen ions, such as hydrochloric acid. The tunnel-shaped etching pits are further expanded in diameter by passing a direct current through them in an acidic aqueous solution containing halogen ions, such as nitric acid. Sponge-like etching pits form a sponge-like layer with a series of fine voids. These sponge-like etching pits are formed by passing an alternating current through the base foil in an acidic aqueous solution containing halogen ions, such as hydrochloric acid. In other words, the surface portion of the metal foil where etching pits are formed becomes the expanded surface layer 515, and the central portion in the thickness direction of the metal foil where etching pits are not formed becomes the core metal portion 514.

[0023] Furthermore, the powder is a valve metal powder of the same or different type as the foil. This powder is obtained by methods such as grinding, atomization, melt spinning, rotating disk method, and rotating electrode method. The atomization method can be water atomization, gas atomization, or water-gas atomization. When the powder layer is formed by sintering, it is made into a paste with a binder or solvent, applied to the metal foil and dried, and then heated and sintered in a vacuum or reducing atmosphere. When the powder layer is formed by vapor deposition, this powder layer is made by methods such as resistance heating vapor deposition or electron beam heating vapor deposition. That is, the powder layer formed by vapor deposition is created by heating a valve metal of the same or different type as the foil with resistance heat or electron beam energy to evaporate it, and depositing the vapor of valve metal particles onto the surface of the base foil. In these cases, the powder layer formed on the surface of the metal foil becomes the expanding layer 515, and the metal foil becomes the core metal portion 514.

[0024] Furthermore, a dielectric film (not shown) is formed on the uneven surface of the expanding layer 515 of the anode foil 510. The dielectric film is typically an oxide film formed on the uneven surface of the expanding layer 515, and if the anode foil 510 is made of aluminum, it is an aluminum oxide layer obtained by oxidizing the uneven surface of the expanding layer. In the chemical conversion treatment to form the dielectric film, a voltage is applied to the anode foil in the conversion solution to achieve a desired withstand voltage. The conversion solution is a halogen ion-free solution, such as a phosphoric acid-based conversion solution such as ammonium dihydrogen phosphate, a boric acid-based conversion solution such as ammonium borate, or an adipic acid-based conversion solution such as ammonium adipate. In the chemical conversion treatment to form the dielectric film, it is preferable to form a dielectric film with a thickness of 0.9 to 1.5 nm in order to obtain a withstand voltage of 1 V.

[0025] As mentioned above, in order to improve capacitor capacitance, the surface area of ​​the anode foil is increased by increasing the density of the expanding layer. However, forming a chemical conversion film (oxide film) on the surface of the high-density expanding layer tends to reduce the flexibility of the metal foil using valve metals such as aluminum (because the chemical conversion film is hard and brittle). As a result, it is known that cracks are more likely to occur in the anode foil when stress or load is applied to the electrode foil, such as when connecting the electrode foil to the lead terminals or when winding and forming the capacitor element.

[0026] To suppress the occurrence of such unexpected cracks, it has been proposed to pre-form a segmented portion 516 in the widening layer 515, as shown in Figures 1(b) and 1(c), in order to prevent the occurrence of unexpected cracks that could significantly affect the characteristics and processability of the anode foil and capacitor element. Figure 1(b) is a conceptual plan view of the surface of the anode foil 510 observed from direction A in Figure 1(a), and Figure 1(c) is a conceptual side view of the cross-section of the anode foil 510 observed from direction B in Figure 1(a). For example, Japanese Patent No. 6723252 discloses a method for manufacturing an anode foil equipped with such segmented portions, and a method for manufacturing a wound capacitor. The segmented portion 516 is pre-formed with cracks to the extent that it does not adversely affect the characteristics of the capacitor, thereby ensuring the desired flexibility of the anode foil.

[0027] In Figure 1(c), the dividing portion 516 is formed to a desired depth that does not reach the core metal portion 514 of the anode foil, thereby dividing at least the surface of the expanding layer 515. The dividing portion 516 does not need to go so far as to completely sever the core metal portion 514, and may be to a depth that does not reach the core metal portion 514, a depth where the deepest part just reaches the core metal portion 514, or a depth where the deepest part bites into the core metal portion 514. Furthermore, the depths of all the dividing portions 516 on a single anode foil 510 do not need to be the same.

[0028] Furthermore, the dividing portion 516 has a desired length in a direction perpendicular to the longitudinal direction of the anode foil 510, i.e., in the width direction of the anode foil 510, so as to ensure flexibility that the anode foil 510 can be easily wound. The dividing portion 516 extends to completely or partially traverse the anode foil 510. That is, some dividing portions 516 extend from one long side of the anode foil 510 to the other long side. Others extend from one long side of the anode foil 510 to below or beyond the foil centerline and not to the other long side. Others extend from the other long side of the anode foil 510 to below or beyond the foil centerline and not to the one long side. Dividing portions 516 formed along the width direction may be connected to each other. The direction and length of all the divisions 516 on a single anode foil 510 do not need to be the same.

[0029] Furthermore, the divided portion 516 exhibits a state of multiple linear trenches / scratches or thin recesses, and is provided on both sides of the foil in principle. This divided portion 516 is formed by cracking the expanding layer 515, tearing the expanding layer 515, making cuts in the expanding layer 515 along the thickness direction of the anode foil 510, notching the expanding layer 515, or carving out the expanding layer 515 along the thickness direction of the anode foil 510. Therefore, examples of embodiments of the divided portion 516 include cracks, tears, cuts, notches, or carvings. However, the form of the divided portion 516 is not particularly limited as long as the expanding layer 515 is divided. Furthermore, the statement that the dividing portion 516 is in the width direction of the foil and is in a thin linear shape means that the dividing portion 516 does not have to be a straight line but a curve, and that the overall stretching direction when observing one dividing portion 516 is generally the width direction of the anode foil 510.

[0030] The groove width of the divided portion 516 is 50 μm or less, including 0, when the anode foil 510 is flattened without curving. The groove width of the divided portion 516 is the length along the longitudinal direction of the anode foil 510, measured near the surface layer of the anode foil 510. If the divided portion 516 is formed by cracking, tearing, or cutting, the groove width of the divided portion 516 becomes substantially 0. Substantially 0 means that when the anode foil 510 is flattened without curving, the interface of the divided portion 516 is at least partially in contact. If the groove width of the divided portion 516 is 50 μm or less, a large decrease in the capacitance of the wound capacitor due to the reduction in the surface area of ​​the dielectric film can be suppressed without impairing the flexibility and stretchability of the anode foil 510.

[0031] Here, one possible method for forming the divided portion 516 is by physical means, such as pressing the anode foil 510 onto a round bar. In the formation method using a round bar, the core metal portion 514 of the anode foil 510 stretches in the longitudinal direction, resulting in a reduction in the thickness of the core metal portion 514. However, by setting the groove width of the divided portion 516 to 50 μm or less, the thickness of the core metal portion 514 is less likely to decrease, and the flexibility and stretchability of the anode foil 510 are improved. In this respect as well, it is preferable to set the groove width of the divided portion 516 to 50 μm or less.

[0032] Furthermore, the divided sections 516 are provided at four or more locations per 10 mm in the longitudinal direction of the anode foil 510. If the number of divided sections 516 is small, even if the bending stress is distributed to each divided section 516 when winding the anode foil 510, the stress on each divided section 516 will be large, making it easier for cracks and foil splitting to occur that can also destroy the core metal section 514 from the divided sections 516. The spacing between adjacent divided sections 516 should be such that the average pitch is 2.1 mm or less, and more preferably the average pitch is 1.0 mm or less. If the average pitch is 2.1 mm or less, the exelin value will be larger compared to electrode foil without divided sections 516.

[0033] The average pitch was calculated by selecting several arbitrary locations along the longitudinal direction of the anode foil 510, calculating the average distance between four consecutive divisions 4 selected from each cross-sectional photograph, and then taking the average of these average values. The distance between the divisions 516 was obtained by measuring near the surface of the anode foil 510.

[0034] A dielectric film (not shown) is formed on the surface of the expanding layer 515. The dielectric film is formed by chemical conversion treatment of the expanding layer 515, and typically uses an oxide film formed by applying a voltage in a halogen-free solution such as an aqueous solution of adipic acid or boric acid. Here, it is preferable to also form the dielectric film on the inner surface of the divided portion 516. Forming a dielectric film on the surface of the divided portion 516 increases the stability of the anode foil 510. Furthermore, forming a dielectric film on the inner surface of the divided portion 516 reduces the amount of electricity (A·s / F) required for the aging treatment to repair the dielectric film.

[0035] [Capacitor]

[0036] Figure 5 shows an example of a connection portion 700 between the anode foil 510 and the lead terminal 600 of a capacitor according to an embodiment. In Figure 5(a), the edge portion of the lead terminal 600 hidden by the anode foil 510 is shown by a dashed line. The configuration shown in Figure 5 is an example, and the technical concept of this disclosure is not limited to the configuration described herein. In this embodiment, the connection portion 700 includes the connection portion 700 formed by the anode foil 510 being pressed against the lead terminal 600 by the pressing portion 100 of the cold pressure welding die, and the surrounding portion thereof.

[0037] Furthermore, the capacitor is an example of an electronic component, and may be, for example, an electrolytic capacitor, or even an aluminum electrolytic capacitor. The capacitor includes, for example, a capacitor element (not shown), lead terminals 600, an electrolyte (not shown), a sealing member, and an outer casing.

[0038] A capacitor element includes an anode foil 510, a cathode foil, and a separator. The anode foil 510, cathode foil, and separator are stacked and wound together so that the separator is positioned between the anode foil 510 and the cathode foil, thereby forming a wound element. This wound element forms a capacitor element.

[0039] The anode foil 510 that is wound around the foil is one that has the aforementioned divided portion 516 formed on it beforehand.

[0040] The cathode foil, like the anode foil 510, is formed by expanding a metal foil made of the valve metal described above, and is shaped into a metal foil selected from the valve metals described above. The etching process for the metal foil is the same as for the anode foil 510, so the explanation is omitted here. An oxide film is formed on the expanded layer of the cathode foil, and this oxide film may be intentionally formed or naturally occurring (spontaneous oxide film). The oxide film is formed by a chemical conversion treatment in which a voltage is applied in a halogen ion-free solution such as an aqueous solution of adipic acid or boric acid, and is a thin oxide film of about 1 to 10 V. The spontaneous oxide film is a thin oxide film formed by the reaction of the cathode foil with oxygen in the air. In addition, this cathode foil may be a carbon foil in which a carbon layer is laminated on the expanded layer.

[0041] A separator is placed between the anode foil 510 and the cathode foil to prevent a short circuit between the anode foil 510 and the cathode foil. The separator is an insulating material and may include, for example, kraft, and may also include other separator materials such as Manila hemp, esparto, hemp, rayon, cellulose, or mixtures thereof.

[0042] The lead terminal 600 is made of a conductive metal such as aluminum. The lead terminal 600 is, for example, a tab terminal or a lead terminal. A tab terminal includes a flat portion made of a thin, strip-shaped metal foil, as shown in Figure 5(a). One end of the tab terminal is connected to an external terminal attached to a sealing member. A lead terminal includes a lead wire and a terminal portion. The lead wire is connected to the terminal portion by, for example, arc welding. The terminal portion comprises a roughly cylindrical round bar portion and a flat portion formed by, for example, press working. The round bar portion has an inclined portion on the side of the flat portion, in which the thickness decreases linearly to the thickness of the flat portion.

[0043] The flat portion of the lead terminal 600 is, for example, a thin metal plate or metal tab, and has a strip shape. The flat portion is superimposed on the anode foil 510 and connected to the anode foil 510 by pressure welding, such as cold pressure welding, at a plurality of connection portions 700. In other words, the connection portions 700 are formed by pressure welding by the pressing portion 100 of a cold pressure welding die. As shown in Figure 5(a), the connection portion 700 has a shape with a long side and a short side when viewed from the surface of the anode foil 510 in a plan view, with the short side positioned in the width direction of the anode foil 510, i.e., in the direction in which the dividing portion 516 is formed. In this application, the arrangement of the short side in the width direction of the anode foil 510 or the direction of formation of the divided portion 516 is not limited to the short side of the connecting portion 700 being in the same direction as the width direction of the anode foil 510 or the direction of formation of the divided portion 516. The short side of the connecting portion 700 may have an angle with respect to the width direction of the anode foil 510 or the direction of formation of the divided portion 516, as long as it is within the range of having the effects of the present invention. For example, if the short side of the connecting portion 700 is at an angle of about 30° with respect to the width direction of the anode foil 510 or the direction of formation of the divided portion 516, it is included in the capacitor of the present invention. Also, in Figure 5, the connecting portion 700 has a rectangular shape with a long side and a short side, but it is not limited to a rectangular shape as long as it has a long side and a short side. For example, it may be a trapezoid, a parallelogram, or a triangle.

[0044] The connection portion 700 may be defined as the location where the lead terminal 600 is connected to the anode foil 510, or it may be defined as the lead terminal 600 and the anode foil 510 present at that location. The connection portion 700 of the lead terminal 600 is connected to the connection portion 700 on the anode foil 510 side by pressure contact. In the cross-section shown in Figure 5(b) (cross-section along the BB line in Figure 5(a)), the connection portion 700 has, for example, a trapezoidal pressure mark, and in the cross-section perpendicular to the BB line in Figure 5(a), it also has, for example, a trapezoidal pressure mark. Therefore, the connection portion 700 has a bottom portion and a sloped portion.

[0045] In Figure 5(a), the connecting parts 700 may be arranged in a line at equal intervals, for example. However, the connecting parts are not limited to this arrangement; they may be arranged at uneven intervals, and they may be arranged in two or more lines, or at any interval S.

[0046] The number of connection portions 700 is determined, for example, by the length over which the flat portion overlaps the anode foil 510. To stabilize the mechanical and electrical connection between the lead terminal 600 and the anode foil 510, it is preferable that there be three or more connection portions 700.

[0047] The cathode foil is connected to a cathode lead terminal (not shown) by cold pressure welding or other connection means.

[0048] The electrolyte can be a liquid electrolyte, a gel electrolyte, or a solid electrolyte containing a conductive polymer. The electrolyte may also consist of a liquid electrolyte or a gel electrolyte and a solid electrolyte, forming a so-called hybrid electrolytic capacitor.

[0049] The electrolyte comprises a solvent and a solute dissolved in the solvent, and may further contain additives. The solvent may be either a protic polar solvent or an aprotic polar solvent. Examples of protic polar solvents include monohydric alcohols, polyhydric alcohols, oxyalcohol compounds, and water. Examples of aprotic polar solvents include sulfones, amides, lactones, cyclic amides, nitriles, and oxides. The solute comprises anionic and cationic components and is typically an organic acid or its salt, an inorganic acid or its salt, or a complex compound of an organic acid and an inorganic acid or an ionically dissociable salt thereof, and is used alone or in combination of two or more. The anionic acid and the cationic base may be added separately to the electrolyte as solute components.

[0050] The solid electrolyte has, for example, an electrolyte layer containing a conductive polymer. The conductive polymer is a conjugated polymer or a doped conjugated polymer. The conjugated polymer is a known conjugated polymer such as polypyrrole, polythiophene, polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylenevinylene, polyacene, and polythiophenevinylene, with poly(3,4-ethylenedioxythiophene) being preferred. The conjugated polymer may be a single conjugated polymer, a composite conjugated polymer, or a copolymer of two or more monomers.

[0051] When tab terminals are used as the lead terminals 600, the sealing member may be, for example, a phenolic laminate with external terminals attached. The external terminals attached to the phenolic laminate are connected to one end of the tab terminals protruding from the capacitor element. When lead terminals are used as the lead terminals 600, the sealing member may be made of, for example, insulating rubber. The sealing member made of insulating rubber has an insertion hole at a position corresponding to the lead terminals protruding from one end face of the capacitor element, and the round bar portion and metal wire of the lead terminals pass through the insertion hole of the sealing member, exposing the lead terminals to the outside of the capacitor.

[0052] The outer casing is, for example, a bottomed cylindrical aluminum case. The capacitor element and part of the lead terminals 600 are housed inside the outer casing along with the electrolyte, and a sealing member is installed at the opening of the outer casing to seal the inside of the outer casing. In other words, the capacitor element and part of the lead terminals 600 are sealed inside the outer casing.

[0053] [Capacitor manufacturing process]

[0054] The capacitor manufacturing process is an example of the capacitor manufacturing method of the present disclosure and includes, for example, a process for manufacturing an anode foil 510, a process for manufacturing a cathode foil, a process for manufacturing lead terminals 600, a process for manufacturing a separator, a process for connecting the lead terminals 600 to the electrode foil, a process for manufacturing a capacitor element, and a process for encapsulating the capacitor element.

[0055] In the process of manufacturing the anode foil 510, for example, a porous expansion layer is formed on the surface of a metal foil made of the valve metal described above, and a dielectric film is formed on the surface of the expansion layer by a chemical conversion treatment. The expansion portion is formed, for example, by etching or particle deposition treatment. The etching treatment may be DC etching or AC etching. In DC etching or AC etching, typically a DC current or AC current is applied to a valve metal foil immersed in an acidic aqueous solution containing halogen ions, such as hydrochloric acid. In particle deposition treatment, metal particles or the like are deposited or sintered onto the valve metal foil. The anode foil 510 is manufactured by cutting the metal foil on which the dielectric film has been formed.

[0056] In the cathode foil manufacturing process, for example, an etching treatment or particle deposition treatment is used to form irregularities on the surface of the valve-acting metal foil described above. The etching treatment or particle deposition treatment of the cathode foil may be the same as or different from that of the anode foil. A carbon layer may also be formed on the metal foil.

[0057] In the manufacturing process of the lead terminal 600, in the case of a tab terminal, a metal foil made of a conductive metal such as aluminum is cut to the desired size to produce the lead terminal 600. In the case of a lead terminal, a part of a round bar made of a conductive metal such as aluminum is pressed to produce the aforementioned terminal part which has a flat part. A lead wire is connected to the aforementioned terminal part, for example by arc welding, to produce the lead terminal.

[0058] In the separator manufacturing process, the separator components described above are cut to produce the separators.

[0059] In the process of connecting the lead terminals 600 to the anode foil 510 and the cathode foil, the lead terminals 600 are connected to the anode foil 510 and the cathode foil, respectively.

[0060] In the process of connecting the lead terminals 600 to the anode foil 510 and cathode foil, first the lead terminals 600 are placed on the pressure receiving plate, and then the anode foil 510 is placed on top of the lead terminals 600. The anode foil 510 and lead terminals 600, which are stacked on top of each other, are positioned between the pressing part 100 and the pressure receiving plate such that the anode foil 510 is positioned on the side facing the pressing part 100.

[0061] The lead terminal 600 is cold-welded to the anode foil 510 by, for example, cold pressure welding. In the cold pressure welding process, the distance between the pressing part 100 and the pressure receiving plate is narrowed in a non-heated state, and the pressing part 100 presses the anode foil 510 and the lead terminal 600, for example, from the anode foil 510 side. The pressing part 100 has at least one projection, which is a pressing part 100, in the part that contacts the anode foil 510 (the pressing part 100 part). As shown in Figure 2(a), the pressing part 100 has a rectangular shape with a long side and a short side in plan view. In Figure 2, the pressing part 100 has a rectangular shape with a long side and a short side, but it is not limited to a rectangular shape as long as it has a long side and a short side, and the pressing part 100 may have a trapezoidal, parallelogram, or triangular shape in plan view. The pressing portion 100 forms a connection portion 700 by the pressure applied by the cold pressure welding die, and the lead terminal 600 is cold pressure welded to the anode foil 510 at the connection portion 700. At this time, the short side of the pressing portion 100 is positioned in the width direction of the anode foil 510, that is, in the direction in which the division portion 516 is formed, and the pressing portion 100 presses the anode foil 510 and the lead terminal 600. In this application, positioning the short side of the pressing portion 100 in the width direction of the anode foil 510 or the direction in which the division portion 516 is formed is not limited to the short side of the pressing portion 100 being in the same direction as the width direction of the anode foil 510 or the direction in which the division portion 516 is formed. Within the range in which the effects of the present invention are achieved, the pressing portion 100 may press the anode foil 510 and the lead terminal 600 with the short side of the pressing portion 100 at an angle to the width direction of the anode foil 510 or the direction in which the division portion 516 is formed. For example, if the short side of the pressing portion 100 is at an angle of about 30° with respect to the width direction of the anode foil 510 or the direction in which the dividing portion 516 is formed, and the pressing portion 100 presses the anode foil 510 and the lead terminal 600, then it is included in the capacitor of the present invention.

[0062] The process for connecting the lead terminals to the cathode foil may be the same as, or different from, the process for connecting the lead terminals to the anode foil 510.

[0063] In the capacitor element fabrication process, a separator is placed between the anode foil 510 and the cathode foil. The anode foil 510, cathode foil, and separator are wound together to fabricate the capacitor element.

[0064] In the capacitor element encapsulation process, the capacitor element is impregnated with an electrolyte solution, and then the lead terminals 600 extending from the capacitor element are connected to external terminals attached to a sealing member. After that, the capacitor element is inserted into the outer casing. Finally, the capacitor element is sealed by crimping the sealing member placed at the opening of the outer casing, and the capacitor is manufactured.

[0065] The capacitors, electronic components, electronic devices, and their manufacturing and molding methods, structures, and configurations described above are not limited to the specific descriptions illustrating numerical values, structures, configurations, and procedures in the examples, but are broadly applicable to any electronic component, and the structure, materials, process content, sequence, and procedures can be appropriately changed, arranged, and modified within the scope of the technical concept of the present invention, which is obvious to those skilled in the art. Specifically, the electrode foil is not limited to anode foil. In bipolar (nonpolar) capacitors, there may be no difference in electrode characteristics, but it is easily understood by those skilled in the art that the technical concept of the present invention can be applied.

[0066] [Examples] In the embodiment, the connection state between the divided portion 516 formed on the anode foil 510 and the connection portion formed by the cold pressure welding method is observed and confirmed. Here, considering the winding direction when wound as a capacitor, the divided portion 516 is usually formed linearly in the width direction (short side direction) of the anode foil 510. When attempting to connect such a divided portion 516 to the lead terminal 600 in a subsequent process using the cold pressure welding method on an anode foil 510 provided on an expanding layer 515, the inventors have found that the relationship between the orientation of the pressing portion 100 of the cold pressure welding die, which is rectangular in plan view, and the direction of the divided portion 516 is greatly related to foil cracking, as shown in Figure 2. In this experiment, the pressing portion 100 of the cold pressure welding die was a rectangular shape in plan view, with the long side and short side being perpendicular to each other.

[0067] Figure 2(a) is a conceptual plan view of the pressing portion 100 that contacts the connection target portion of the cold pressure welding die, Figure 2(b) is a conceptual front view of the pressing portion 100 observed from direction A in Figure 2(a), and Figure 2(c) is a conceptual left side view of the pressing portion 100 observed from direction B in Figure 2(a). Figure 3 shows a micrograph of the connection portion 700 formed by pressing the cold pressure welding die to obtain a connection between the anode foil 510 and the lead terminal 600. The anode foil 510 is a type of anode foil with reduced flexibility and a high magnification ratio, which has been used in recent years to meet the demand for higher capacity. In the process of attaching the lead terminal, the anode foil 510 is placed on the lead terminal 600, and the anode foil 510 is pressed down from above with the pressing part 100 of the cold pressure welding die, so that the anode foil 510 is pressed against the lead terminal 600 and crushed, thereby integrating the anode foil 510 and the lead terminal 600 and creating an electrical connection.

[0068] As can be seen from the magnified photograph in Figure 3(a), foil cracking is observed in the peripheral area along the long side of the pressing mark 100 of the rectangular cold welding die at the connection point 700 between the anode foil 510 and the lead terminal 600. Also, as can be seen from the magnified photograph in Figure 3(b), foil cracking is observed in the peripheral area extending along the long side of the pressing mark 100 of the rectangular cold welding die between the connection point 700 between the anode foil 510 and the lead terminal 600 and other adjacent connection points 700. In Figure 3, the locations of the foil cracks are indicated by arrows. There is a concern that the foil cracks shown in Figure 3, which were caused by the connection process between the anode foil 510 and the lead terminal 600 due to the pressing of the cold welding die, will be further exacerbated and amplified during the subsequent winding process.

[0069] Further detailed observation and research revealed that the foil cracks shown in Figure 3 are closely related to the direction of the divided portion 516, which was originally provided to ensure the flexibility of the anode foil 510, and that the foil cracks occur in the direction of the divided portion 516. In other words, in pursuit of higher capacitance of capacitors, the expanded surface layer 515 of the anode foil 510 was made denser, and the divided portion 516 was provided to address the weakening of the anode foil 510. However, it was found that the subsequent pressing process of the cold pressure welding die induces cracks in the divided portion 516. Based on this finding, the inventors conducted the following experiments to confirm whether this solution is useful for anode foil 510 of a certain degree of fragility.

[0070] Therefore, the inventors prepared anodic foils 1 to 4 with different hardness and expansion methods as shown in Figure 4(a), and compared them by conducting experiments using the Erichsen value as an indicator of hardness, pressing the pressing part 100 of a cold welding die against them as explained in Figure 4(b). The left side of Figure 4(b) illustrates the state in which the long side of the pressing part 100 of the cold welding die is pressed in a direction parallel to the direction of the division portion 516, and the right side of Figure 4(b) illustrates the state in which the long side of the pressing part 100 of the cold welding die is pressed in a direction perpendicular to the direction of the division portion 516. The likelihood of foil cracking occurring in both of these cases was compared for each of the four anodic foils 1 to 4. In all of the anodic foils shown in Figure 4(a), multiple division portions were pre-formed in the same amount under the same conditions in the width direction of each anodic foil. Specifically, in Figure 4(b), the anode foils 1 to 4 were connected to the lead terminals 600 by combining them with the pressing shape of the cold welding die, and samples 1 to 8 were prepared. An experiment was conducted to verify the relationship between the brittleness characteristics of the anode foil 510 and the shape of the pressing part 100 of the cold welding die (rectangular shape in plan view).

[0071] In the Erichsen test, each anode foil was sandwiched and pressed with a punch that had a chisel-shaped tip. The speed at which the chisel portion of the punch was pressed along the short side of the electrode foil was set to 1.0 mm / min.

[0072] Figure 4(c) is a table describing the type of expanded surface layer, the Erichsen value indicating flexibility, the shape of the pressing part 100 of the cold welding die, and the presence or absence of foil cracks at the connection points and between connection points for each sample, for samples 1 to 8 (i.e., one vertical and one horizontal for each anode foil) prepared by combining the shapes of anode foils 1 to 4 and the pressing part 100 of the cold welding die. In the table in Figure 4(c), "vertical" in the column for the shape of the pressing part 100 of the cold welding die indicates that the connection was made by pressing the long side of the pressing part 100 of the cold welding die in a direction parallel to the direction of the division point, as shown on the left side of Figure 4(b), and "horizontal" indicates that the connection was made by pressing the long side of the pressing part 100 of the cold welding die in a direction perpendicular to the direction of the division point 516, as shown on the right side of Figure 4(b). Furthermore, the presence or absence of foil cracks was evaluated as present when the condition shown in Figure 3 was observed.

[0073] In Figure 4, the Erichsen value with a tunnel-shaped etched expansion layer is 5.18 N / mm². 2 In the cold pressure welding die using the anode foil 1, the shape of the pressing portion 100 differed between the vertically elongated sample 1 and the horizontally elongated sample 2. Foil cracking was observed in the vertically elongated sample, but not in the horizontally elongated sample. Furthermore, the Erichsen value with a tunnel-shaped etching expansion layer was 6.53 N / mm². 2 In the cold pressure welding die using the anode foil 2, the shape of the pressing portion 100 differed between the vertically elongated sample 3 and the horizontally elongated sample 4. Foil cracking was observed in the vertically elongated sample, but not in the horizontally elongated sample.

[0074] Furthermore, the Erichsen value with a tunnel-shaped etched expansion layer is 6.66 N / mm². 2 In the cold pressure welding die using the anode foil 3, the shape of the pressing portion 100 differed between the vertically elongated sample 5 and the horizontally elongated sample 6. No foil cracking was observed in the vertically elongated sample, and no foil cracking was observed in the horizontally elongated sample either. Furthermore, the Erichsen value with a powder laminated widening layer was 5.62 N / mm². 2 In the cold pressure welding die using the anode foil 4, when comparing the shape of the pressing portion 100 between the vertically elongated sample 7 and the horizontally elongated sample 8, foil cracking was observed in the vertically elongated sample, but not in the horizontally elongated sample.

[0075] Based on the results in Figure 4(c), it can be understood that foil cracking occurs when the long side of the pressing portion 100 of the cold welding die is connected to the cold welding weld in a direction parallel to the direction of the separation. This is likely due to the synergistic effect of the stress from the long side of the pressing portion 100 of the cold welding die and the crack direction of the separation.

[0076] Furthermore, regardless of whether the expanded layer is formed by etching or powder lamination, the Erichsen value is 6.53 N / mm². 2 Considering that foil cracking is observed only when the following anode foil is used, this method of adjusting the pressing direction of the pressing portion 100 of the cold pressure welding die, which is rectangular in plan view, relative to the dividing portion, is effective when the Erichsen value is 6.53 N / mm 2 It can be seen that this technical concept is particularly effective in the case of the following electrode foils. [Industrial applicability]

[0077] The present invention is suitable for manufacturing processes of various types of capacitors, such as aluminum electrolytic capacitors, and various electronic components that have a connection between an electrode foil with a divided surface layer and a lead terminal. [Explanation of Symbols]

[0078] 510... Anode foil, 514... Core metal section, 515... Expanding layer, 516... Separation section, 600... Lead-out terminal, 700... Connection section.

Claims

1. An electrode foil having an expanded surface layer with a divided portion, A capacitor comprising a connection portion in which the electrode foil and the terminal are connected by a cold pressure welding method, The divided portion is formed in the width direction of the electrode foil, The connecting portion has a shape with a short side and a long side in a plan view, and the short side is arranged in the width direction of the electrode foil. A capacitor characterized by the following features.

2. In the capacitor according to claim 1, The longer side of the connecting portion is perpendicular to the dividing portion. A capacitor characterized by the following features.

3. In the capacitor according to claim 1 or claim 2, The Erichsen value of the electrode foil is 6.53 N / mm². ２ The following is A capacitor characterized by the following features.

4. A step of providing a divided portion in the width direction of the electrode foil in the expanding layer of an electrode foil having an expanding layer, The process includes connecting the electrode foil and the terminal by a cold pressure welding method using a cold pressure welding die, The cold pressure welding die is provided with a pressing portion having a short side and a long side in a plan view, and cold pressure welding is performed with the short side of the pressing portion positioned in the width direction of the electrode foil. A method for manufacturing a capacitor characterized by the following:

5. In the method for manufacturing a capacitor according to claim 4, The long side of the pressing portion is positioned perpendicular to the dividing portion and cold-pressed. A method for manufacturing a capacitor characterized by the following:

6. In the method for manufacturing a capacitor according to claim 4 or claim 5, The Erichsen value of the electrode foil is 6.53 N / mm². ２ The following is A method for manufacturing a capacitor characterized by the following:

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