JP2023146859A - Capacitor and method for manufacturing the same - Google Patents

Abstract

To provide a stitch connection structure suitable for a cathode foil including, for example, a carbon layer.SOLUTION: A capacitor (2) includes a cathode foil (6) including a carbon layer formed on a surface of a base material foil, and a lead-out terminal (4) connected to the cathode foil by stitch connection. The lead-out terminal includes a metal wire (17) and a flat portion (18) connected to the cathode foil. A press mark end (32) formed on a metal wire side of the flat portion by the stitch connection protrudes from a foil end (30) of the cathode foil, or coincides with the foil end, or overlaps with the cathode foil at an interval of 0.1 millimeter or less from the foil end.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a capacitor including a cathode foil including a carbon layer and a method for manufacturing the same.

A capacitor includes an anode foil, a cathode foil, and a separator disposed between the anode foil and the cathode foil, and is capable of storing electricity. Regarding such capacitors, capacitors including a cathode foil made of aluminum foil are known. Furthermore, in recent years, capacitors including a cathode foil containing a carbon layer have been known (for example, Patent Document 1). The carbon layer has the effect of increasing the capacitance of the cathode foil, for example.

Japanese Patent Application Publication No. 2006-80111

The electrode foil is connected to the lead terminal by a connecting means such as a stitch connection. In the stitch connection process for forming a stitch connection, a stitch needle is inserted through the stacked lead terminal and electrode foil from the lead terminal side, a terminal hole and a terminal piece are formed in the lead terminal, and a through hole and a terminal piece are formed in the electrode foil. Pieces are formed. The terminal piece passes through the through hole in the electrode foil and protrudes from the back surface of the electrode foil. The terminal piece and foil piece are pressed and stacked on the back side of the electrode foil. As a result, a stitch connection is formed and the electrode foil is connected to the lead terminal.

By the way, the carbon layer is formed, for example, by applying a slurry mainly composed of carbon particles and a binder to the surface of an aluminum foil, and bonding the carbon particles together with the binder. In a cathode foil containing a carbon layer, the binder contained in the carbon layer generates stress directed outward from the pressed part in response to the pressing force on the carbon layer, causing stress to be generated in a cathode foil made only of metal foil such as aluminum foil. In comparison, a cathode foil containing a carbon layer is easier to stretch. In the stitch connection process of a cathode foil having a carbon layer, when the terminal piece and the foil piece are pressed, the carbon layer stretches, and the base material of the cathode foil stretches following the carbon layer. In other words, there is a problem that a cathode foil having a carbon layer is more easily stretched than a cathode foil not including a carbon layer in the stitch connection process. Furthermore, when the cathode foil having the carbon layer stretches, there is a problem that the strength of the cathode foil decreases.

Patent Document 1 does not disclose or suggest such a problem, and the configuration disclosed in Patent Document 1 cannot solve this problem.

Therefore, an object of the present disclosure is to provide a stitch connection structure suitable for, for example, a cathode foil including a carbon layer.

In order to achieve the above object, according to a first aspect of the present disclosure, a capacitor includes a cathode foil including a carbon layer formed on a surface of a base foil, and an extraction terminal connected to the cathode foil by a stitch connection. including. The pull-out terminal has a metal wire and a flat part connected to the cathode foil, and a press mark end formed on the metal wire side of the flat part by the stitch connection protrudes from the foil end of the cathode foil, Alternatively, it coincides with the foil edge, or overlaps the cathode foil at a distance of 0.1 mm or less from the foil edge.

In the above capacitor, the terminal end of the lead-out terminal may protrude from the other foil end of the cathode foil, or may coincide with the other foil end, or may be 0.1 mm from the other foil end. It may overlap the cathode foil with an interval of less than a millimeter or more than 0.5 mm.

In order to achieve the above object, according to a second aspect of the present disclosure, a capacitor manufacturing method includes a step of manufacturing a lead terminal including a metal wire and a flat portion, and a carbon layer formed on a surface of a base foil. a step of producing a cathode foil comprising: arranging the flat part of the lead-out terminal on the cathode foil, and forming a press mark end formed on the metal wire side of the flat part by pressing with a mold into the cathode foil; or such that the press mark edge is aligned with the foil edge, or such that the press mark edge overlaps the cathode foil at an interval of 0.1 mm or less from the foil edge; pressing the lead-out terminal with the mold to connect the lead-out terminal to the cathode foil through a stitch connection;

In the step of connecting the drawer terminal to the cathode foil, the drawer terminal may be connected to the cathode foil such that the terminal end of the drawer terminal protrudes from the other foil end of the cathode foil, or In the step of connecting the terminal to the cathode foil, the terminal end is aligned with the other foil end or overlaps the cathode foil at an interval of 0.1 mm or less or 0.5 mm or more from the other foil end. The lead terminal may be connected to the cathode foil.

In order to achieve the above object, according to a third aspect of the present disclosure, a method for manufacturing a capacitor including a cathode foil including a carbon layer includes a step of producing a lead terminal including a metal wire and a flat part, and a step of pressing a mold. so that the end of the press mark to be formed on the metal wire side of the flat part protrudes from the foil end of the cathode foil, or the end of the press mark is aligned with the foil end, or the press mark is formed on the metal wire side of the flat part. adjusting a stitch connection device such that the end overlaps the cathode foil at a distance of 0.1 mm or less from the foil edge; and stitch-connecting the extraction terminal to the cathode foil using the adjusted stitch connection device. and forming the press mark end at the adjusted position.

In the step of adjusting the stitch connection device, the stitch connection device may be adjusted so that the terminal end of the extraction terminal protrudes from the other foil end of the cathode foil, or the step of adjusting the stitch connection device In the method, the stitch connection device may be adjusted so that the terminal end coincides with the other foil end or overlaps the cathode foil at an interval of 0.1 mm or less or 0.5 mm or more from the other foil end. good.

According to the above aspect of the present disclosure, for example, any of the following effects can be obtained.

(1) Foil cracking caused by cathode foil containing a carbon layer is suppressed. Therefore, the connection between the lead terminal and the cathode foil can be stabilized.

(2) A stitch connection suitable for the properties of the cathode foil can be realized.

(3) The stability or reliability of a capacitor equipped with a cathode foil containing a carbon layer can be improved.

FIG. 3 is a diagram showing an example of a lead terminal and a cathode foil of a capacitor according to an embodiment. FIG. 3 is a diagram showing the results of a first experiment. It is a figure for explaining the presumed mechanism of foil cracking suppression. It is a figure for explaining the presumed mechanism of foil cracking. FIG. 7 is a diagram showing the results of a second experiment. It is a figure for explaining the presumed mechanism of foil cracking suppression. FIG. 3 is a diagram for explaining an estimated mechanism of foil cracking suppression or foil cracking. It is a figure which shows an example of the connection process of the extraction terminal to electrode foil. It is a figure showing a modification.

FIG. 1 shows an example of a lead terminal and a cathode foil of a capacitor according to an embodiment. The configuration shown in FIG. 1 is an example, and the technology of the present disclosure is not limited to such a configuration.

Capacitor 2 is an example of an electronic component, and is, for example, an electrolytic capacitor. The capacitor 2 includes, for example, a capacitor element (not shown), a lead-out terminal 4, an electrolyte (not shown), a sealing member, and an exterior case.

The capacitor element includes a cathode foil 6, an anode foil, and a separator. The cathode foil 6, anode foil and separator are stacked and wound to form a wound element such that the separator is placed between the cathode foil 6 and the anode foil. This wound element forms the capacitor element.

The cathode foil 6 constitutes the cathode side electrode of the capacitor 2 . The cathode foil 6 is, for example, a strip-shaped foil, and includes a base foil and a carbon layer. The base foil is, for example, a valve metal foil such as aluminum foil, tantalum foil, niobium foil, titanium foil, hafnium foil, zirconium foil, zinc foil, tungsten foil, bismuth foil, or antimony foil. On the surface of the base foil, a surface-expanding layer having irregularities, that is, depressions and protrusions formed by etching, for example, is formed, and the surface area of the base foil is expanded. The surface of the base foil may, for example, contain tunnel-like or cavernous etching pits, which may form depressions and protrusions.

The carbon layer is arranged, for example, on both sides of the base foil. The carbon layer may be arranged only on one side of the base foil. The carbon layer partially penetrates into the depressions and depressions of the base foil, so that it closely adheres and engages with the depressions and depressions of the base foil. The carbon layer is arranged on the outside of the base foil, and the cathode foil 6 has a two-layer structure of the base foil and the carbon layer, or a three-layer structure with carbon layers arranged on both sides of the base foil. The carbon layer contains a carbon material as a main material, and further contains a binder and a dispersant as additives.

Examples of the carbon material include activated carbon, carbon black, carbon nanohorn, amorphous carbon, natural graphite, artificial graphite, graphitized Ketjenblack, mesoporous carbon, and fibrous carbon. Activated carbon is produced, for example, from natural plant tissues such as coconut shells, synthetic resins such as phenol, and those derived from fossil fuels such as coal, coke, or pitch. Carbon black is Ketjen black, acetylene black, channel black, thermal black, or the like. Fibrous carbon includes carbon nanotubes, carbon nanofibers, and the like. The carbon nanotube may be a single-walled carbon nanotube with a single layer of graphene sheets, or a multi-walled carbon nanotube (MWCNT) with two or more layers of graphene sheets rolled coaxially to form a multilayered tube wall.

The carbon material is preferably carbon black, which is spherical carbon. By using spherical carbon black with an average primary particle size of 100 nanometers or less, the carbon layer becomes dense and the carbon layer easily adheres to the surface-expanding layer, so that the interface between the carbon layer and the base foil Resistance tends to drop. The carbon material is also preferably a mixture containing spherical carbon and graphite. Graphite is, for example, natural graphite, artificial graphite, or graphitized Ketjenblack, and has a shape such as flaky, scale-like, lump-like, earth-like, spherical, or flake-like. The graphite is preferably in the form of scales or flakes, and the aspect ratio of the short axis to the long axis of the graphite is preferably in the range of 1:5 to 1:100. Scale-like or flaky graphite having the above-mentioned aspect ratio can push spherical carbon into uneven depressions such as etching pits, and a part of the carbon layer can be formed even inside the etching pits. Therefore, the anchor effect allows the carbon layer to firmly adhere to the base foil.

The binder is a resin-based binder such as styrene-butadiene rubber, polyvinylidene fluoride, or polytetrafluoroethylene, and binds the carbon material. The dispersant is, for example, sodium carboxymethyl cellulose. The carbon layer is made, for example, from an aqueous solution in which spherical carbon is dispersed. The dispersant can disperse the carbon material in an aqueous solution.

The anode foil constitutes the anode side electrode of the capacitor 2. The anode foil is, for example, a valve metal foil such as tantalum foil or aluminum foil, and is, for example, a band-shaped foil. The surface of the anode foil has irregularities formed by, for example, etching, and also includes a dielectric oxide film formed by, for example, chemical conversion treatment. The unevenness formed by etching has, for example, a porous structure.

The separator is placed between the anode foil and the cathode foil 6 to prevent short circuits between the anode foil and the cathode foil 6. The separator is an insulating material, including kraft, and may include other separator members such as Manila hemp, esparto, hemp, rayon, cellulose, and mixtures thereof.

The cathode foil 6 is connected to the lead terminal 4 by stitch connection. The anode foil is connected to another lead terminal (not shown) (hereinafter referred to as "drawer terminal 4" for convenience) by stitch connection or other connection means. The lead terminal 4 protrudes from one end surface of the capacitor element. The lead terminal 4 is made of a highly conductive metal, such as aluminum. The lead terminal 4 is composed of, for example, an aluminum wire and a metal wire 17, and the aluminum wire and the metal wire 17 are connected by arc welding or the like. The aluminum wire includes a substantially cylindrical round bar part and a flat part 18 formed by pressing the round bar part. It has an inclined portion where the thickness decreases linearly. The flat portion 18 is superimposed on the cathode foil 6 and connected to this cathode foil 6 by a stitch connection to form a stitch connection. The stitch connection is the area where the terminal piece 24 (FIG. 8) is arranged, and the flat portion 18 is connected to the cathode foil 6 at the stitch connection by a stitch connection.

The electrolyte contains, for example, an electrolytic solution, and is filled in the voids and separators within the capacitor element. A solid electrolyte may be used instead of the electrolyte, or a solid electrolyte layer may be used in addition to the electrolyte. When a solid electrolyte layer is used in combination, the capacitor element on which the solid electrolyte layer is formed is impregnated with an electrolytic solution. Note that the solid electrolyte layer includes a conductive polymer, and the conductive polymer is a conjugated polymer or a doped conjugated polymer. As the conjugated polymer, known ones can be used without particular limitation.

The sealing member is made of, for example, insulating rubber. The sealing member has an insertion hole at a position corresponding to the lead-out terminal 4. The lead terminal 4 passes through the insertion hole of the sealing member and is exposed to the outside of the capacitor 2.

The exterior case is, for example, a cylindrical aluminum case with a bottom. The capacitor element and a portion of the lead-out terminal 4 are inserted into the exterior case together with the electrolyte. A sealing member is installed in the opening of the outer case to seal the inside of the outer case. That is, the capacitor element and a portion of the lead-out terminal 4 are sealed inside the outer case. The pull-out terminal 4 passes through the through hole of the sealing member and protrudes from the sealing member.

As already mentioned, the flat portion 18 is connected to the cathode foil 6 by a stitch connection to form a stitch connection. The flat portion 18 includes a terminal hole 22 and a terminal strip 24 (FIG. 8), and the cathode foil 6 includes a through hole and a foil strip 28 (FIG. 8). The terminal hole 22, the terminal piece 24, the through hole, and the foil piece 28 are formed by inserting a stitch needle 46 (FIG. 8) from the pull-out terminal 4 side. The terminal hole 22 is arranged at a position overlapping the through hole. The terminal piece 24 and the foil piece 28 are folded back by pressure from the cathode foil 6 side, and are pressed against the back surface of the cathode foil 6, that is, the surface opposite to the terminal arrangement surface.

The positions of the press mark end 32 and the terminal end 34 of the pull-out terminal 4 are adjusted or managed with respect to the foil end 30 and the foil end 31 of the cathode foil 6, respectively, so that foil cracking of the cathode foil 6 is suppressed. The press marks are marks formed on the pull-out terminal 4, especially the flat part 18, by pressing with a mold such as the second mold 44 or the molding mold 48 (B in FIG. 3). This is a trace formed on the flat part 18 of the pull-out terminal 4 by pressing the mold end 45 (B in FIG. 3) of the mold 44. In other words, the press mark end 32 represents the boundary of the pressed area. The press mark end 32 is formed, for example, on the metal wire 17 side of the flat portion 18.

The press mark end 32 of the pull-out terminal 4 is recessed from the foil end 30 of the cathode foil 6, for example, and the distance Z1 (unit: mm) between the press mark end 32 and the foil end 30 is adjusted to 0.1 or less. managed. The distance Z1 may be 0.0, and the press mark end 32 may coincide with the foil end 30. That is, the distance Z1 is adjusted or managed, for example, within the range expressed by the following equation (1).
0.0≦Z1≦0.1 ...(1)

Further, the press mark end 32 may protrude from the foil end 30. When the press mark end 32 is adjusted or managed so as to protrude from the foil end 30, foil cracking of the cathode foil 6 is suppressed.

The terminal end 34 of the pull-out terminal 4 is recessed from the foil end 31 of the cathode foil 6, for example, and the distance Y1 (unit: mm) between the terminal end 34 and the foil end 31 is 0.1 or less, or 0.5 It is preferable that it is above. The distance Y1 may be 0.0, and the terminal end 34 may coincide with the foil end 31. That is, the distance Y1 is adjusted or managed, for example, within the range expressed by the following equation (2).
0.0≦Y1≦0.1, or 0.5≦Y1...(2)

When the distance Y1 is 0.5 or more, it is expected that the foil cracking of the cathode foil 6 will be suppressed as the distance Y1 becomes larger. Therefore, the maximum value of the distance Y1 may be set from the viewpoint of the structure or performance of the capacitor 2. Further, the lead terminal 4 may protrude from the foil end 31. The protruding lead terminal 4 prevents the cathode foil 6 from cracking.

FIG. 2 shows the first experimental results, and shows the occurrence of foil cracking at distance Z1 or Z2 (hereinafter referred to as "distance Z1, Z2"). A foil crack is defined as a crack extending from the foil end 30 of the cathode foil 6 to the terminal piece 24 of the stitched connection. Foil cracks may be formed in the cathode foil 6 by pressing the drawer terminal 4 and the cathode foil 6, for example, when the drawer terminal 4 is connected to the cathode foil 6 by stitch connection. Note that in the first experiment, cracks that do not meet the above definitions, such as cracks that do not reach the terminal piece 24, are not treated as foil cracks. The distance Z2 (unit: mm) is defined as the distance between the press mark end 32 of the pull-out terminal 4 protruding from the foil end 30 of the cathode foil 6 and the foil end 30. The first experiment was to check the presence or absence of foil cracking when the distances Z1 and Z2 between the press mark edge 32 and the foil edge 30 were changed as a condition for stitch connection of the drawer terminal 4 to the cathode foil 6 containing the carbon layer. This is an experiment to

When the press mark end 32 protruded from the foil end 30, no foil cracking occurred. Moreover, when the press mark edge 32 coincided with the foil edge 30 or was recessed from the foil edge 30, no foil cracking occurred within the range of distance Z1 expressed by the above formula (1). When the distance Z1 was 0.2 mm (hereinafter referred to as "mm") or 0.3 mm, experimental pieces with foil cracks were confirmed. In the first experiment, it was found that a capacitor 2 that satisfies condition (1) or condition (2) shown below is less likely to cause foil cracking than a capacitor 2 that does not meet conditions (1) or (2). Ta.
Condition (1): The press mark end 32 protrudes from the foil end 30.
Condition (2): Distance Z1 is a value within the range of formula (1) above. In other words, the press mark end 32 coincides with the foil end 30 or overlaps the cathode foil 6 at a distance of 0.1 mm or less from the foil end 30.

When the press mark end 32 protrudes from the foil end 30 as shown in FIG. When the lead terminal 4 is connected to the cathode foil 6 by stitch connection, as shown in FIG. It is sandwiched between and fixed. As already mentioned, the cathode foil 6 including the carbon layer is easier to stretch than the cathode foil not including the carbon layer. However, when the cathode foil 6 and the lead-out terminal 4 are sandwiched between the second mold 44 and the mold 48 so that the press mark end 32 is formed outside the foil end 30, the foil end 30 is fixed. It is estimated that the elongation of the film 30 is suppressed, and the cracking of the cathode foil 6 is also suppressed. When the press mark end 32 is aligned with the foil end 30 and when the press mark end 32 is slightly retracted (for example, 0.1 mm) from the foil end 30, by fixing the foil end 30 or the vicinity of the foil end 30, It is estimated that the elongation of the foil end 30 is suppressed, and it is estimated that the foil cracking of the cathode foil 6 is suppressed.

As shown in FIGS. 4A and 4B, when the press mark end 32 is recessed by 0.2 mm or 0.3 mm from the foil end 30, the cathode foil 6 protrudes from the pressed area of the drawer terminal 4, The foil end 30 and its vicinity become free. Stress from the mold 48 and the lead-out terminal 4 propagates to the foil end 30 of the cathode foil 6 and its vicinity. Therefore, it is estimated that the foil end 30 of the cathode foil 6 including the carbon layer and its vicinity are deformed, and it is estimated that the cathode foil 6 is cracked.

At a distance Z1 of 0.4 mm or more, there is a possibility that there are conditions under which foil cracking of the cathode foil 6 is suppressed. The first experimental results do not suggest that a distance Z1 of 0.4 mm or more will produce results similar to those of 0.2 mm and 0.3 mm.

FIG. 5 shows the second experimental results, and shows the occurrence of foil cracking at distance Y1 or Y2 (hereinafter referred to as "distance Y1, Y2"). The definition of foil cracking is the same as the definition of foil cracking in the first experiment, except that foil end 30 is changed to foil end 31. Note that in the second experiment, cracks that do not meet the above definitions, such as cracks that do not reach the terminal piece 24, are not treated as foil cracks. The distance Y2 (unit: mm) is defined as the distance between the terminal end 34 of the lead terminal 4 protruding from the foil end 31 of the cathode foil 6 and the foil end 31. In the second experiment, the presence or absence of foil cracking was confirmed when the distances Y1 and Y2 between the terminal end 34 and the foil end 31 were changed as a condition for stitch connection of the drawer terminal 4 to the cathode foil 6 containing the carbon layer. This is an experiment for

When the terminal end 34 protruded from the foil end 31, no foil cracking occurred. Further, when the terminal end 34 was aligned with the foil end 31 or recessed from the foil end 31, no foil cracking occurred within the range of distance Y1 expressed by the above equation (2). When the distance Y1 was 0.2 mm, 0.3 mm, or 0.4 mm, experimental pieces with foil cracks were confirmed. In the second experiment, it was found that capacitors 2 that meet condition (3) or condition (4) shown below are less likely to cause foil cracking than capacitors 2 that do not meet conditions (3) or (4). Ta.
Condition (3): The terminal end 34 protrudes from the foil end 31.
Condition (4): Distance Y1 is a value within the range of equation (2) above. In other words, the terminal end 34 coincides with the foil end 31, or overlaps the cathode foil 6 at an interval of 0.1 mm or less or 0.5 mm or more from the foil end 31.

When the terminal end 34 protrudes from the foil end 31 as shown in FIG. 6A, the lead terminal 4 overlaps up to the foil end 31 of the cathode foil 6. Therefore, when the lead terminal 4 is connected to the cathode foil 6 by stitch connection, as shown in B of FIG. It is sandwiched between molds 48 and fixed. As already mentioned, the cathode foil 6 including the carbon layer is easier to stretch than the cathode foil not including the carbon layer. However, when the terminal end 34 protrudes from the foil end 31, it is estimated that the elongation of the foil end 31 is suppressed by fixing the foil end 31, and it is estimated that foil cracking of the cathode foil 6 is suppressed. Ru. When the terminal end 34 is aligned with the foil end 31 and when the terminal end 34 is slightly recessed from the foil end 31 (for example, by 0.1 mm), the foil end 34 is fixed by fixing the foil end 31 or the vicinity of the foil end 31. It is estimated that the elongation of the foil 31 is suppressed, and that the cracking of the cathode foil 6 is suppressed.

When the terminal end 34 is retracted from the foil end 31 as shown in FIG. When the drawer terminal 4 is connected to the cathode foil 6 by stitch connection, the protruding foil end 36 connects to the second mold 44 and the cathode foil 6 via the drawer terminal 4, as shown in FIGS. 7B and 7C. It is not pinched by the mold 48 and is in a free state. When the distance of the protruding foil end 36, that is, the distance Y1, is, for example, 0.5 mm or more and the area of the protruding foil end 36 is wide, the stress propagating from the mold 48 and the lead-out terminal 4 to the cathode foil 6 is It is estimated that this is dispersed in the buffer region 38 including the end portion 36 and its surrounding area, and it is estimated that foil cracking of the cathode foil 6 is suppressed. Note that the arrows in A of FIG. 7 and C of FIG. 7 represent stress propagating to the cathode foil 6.

Even if the terminal end 34 is recessed from the foil end 31, if the distance of the protruding foil end 36, that is, the distance Y1 is, for example, 0.2 mm or more and 0.4 mm or less, and the area of the protruding foil end 36 is narrow, the mold It is presumed that the stress propagating from the terminal 48 and the lead-out terminal 4 to the cathode foil 6 propagates to the protruding foil end 36, and the elongation of the cathode foil 6 due to this stress increases. Therefore, it is presumed that the cathode foil 6 breaks.

Foil cracks in the cathode foil 6 do not affect the performance or vibration resistance of the capacitor 2. However, if more vibration than expected is applied to the metal wire 17 of the capacitor 2 and the vibration propagates to the connection between the lead terminal 4 and the cathode foil 6, the vibration resistance of the capacitor 2 will be affected, for example. Therefore, by adjusting or managing the distances Z1 and Z2 between the press mark end 32 and the foil end 30 so as to satisfy condition (1) or condition (2), the vibration resistance of the capacitor 2 can be improved, and the condition By adjusting or managing the distances Y1 and Y2 between the terminal end 34 and the foil end 31 so as to satisfy (3) or condition (4), the vibration resistance of the capacitor 2 can be improved. Even when used in an environment where vibrations are applied, the equivalent series resistance of the capacitor 2 can be maintained for a long period of time.

[Capacitor manufacturing process]

The manufacturing process of the capacitor 2 is an example of the capacitor manufacturing method of the present disclosure, and includes, for example, an anode foil manufacturing process, a cathode foil 6 manufacturing process, a separator manufacturing process, and a stitch connection device 40 (A in FIG. 8). The process includes an adjustment process, a process of connecting the lead terminal 4 to the electrode foil (hereinafter referred to as "a process of connecting the lead terminal"), a process of manufacturing the capacitor element, and a process of encapsulating the capacitor element.

In the anode foil manufacturing process, the surface of a valve metal foil such as tantalum foil or aluminum foil is etched to form a surface-expanding layer consisting of irregularities on the surface of the valve metal foil. The valve metal foil after the etching treatment is subjected to a chemical conversion treatment to form a dielectric oxide film on the surface of the valve metal foil. An anode foil is produced by cutting the chemically formed valve metal foil.

In the manufacturing process of the cathode foil 6, the surface of a valve metal foil such as aluminum foil, tantalum foil, niobium foil, titanium foil, hafnium foil, zirconium foil, zinc foil, tungsten foil, bismuth foil, or antimony foil is etched. A base foil is produced by forming irregularities on the surface of a valve metal foil. A carbon layer is formed on the valve metal foil after the etching process, that is, the base foil, and the base foil on which the carbon layer is formed is cut to produce the cathode foil 6.

The carbon layer is produced as follows. The above-mentioned carbon material, binder, and dispersant are added to the diluted liquid and mixed by a dispersion process such as a mixer, jet mixing, ultracentrifugation, and ultrasonication to form a slurry. The binder is added, for example, in an amount necessary for binding the carbon material, and the dispersant is added, for example, in the amount necessary for dispersing the carbon material.

Examples of the diluent include alcohol, hydrocarbon solvents, aromatic solvents, amide solvents, water, and mixtures thereof. Alcohol is, for example, methanol, ethanol or 2-propanol. The amide solvent is, for example, N-methyl-2-pyrrolidone (NMP) or N,N-dimethylformamide (DMF).

The slurry is applied to the valve metal foil after the etching process, that is, the base foil. After drying the slurry and volatilizing the solvent to form a carbon layer, the carbon layer is pressed to push the carbon material into the pores of the unevenness and deform the carbon material along the uneven surface of the unevenness.

In the separator production step, the separator member described above is cut to produce a separator.

In the adjustment process of the stitch connection device 40, distances Y1 and Y2 and distances Z1 and Z2 are adjusted. In the process of adjusting the distances Y1 and Y2, for example, the arrangement position of the lead terminal 4 with respect to the cathode foil 6 is adjusted so as to satisfy the above condition (3) or condition (4). For example, the second press mark edge 32 on the cathode foil 6 is applied so that the press mark end 32 that will be formed on the drawer terminal 4 by the pressing of The arrangement position of the mold 44, especially the arrangement position of the mold end 45, is adjusted. The distances Y1, Y2 and the distances Z1, Z2 can be adjusted, for example, by adjusting the position of the alignment device of the lead terminal 4 or the cathode foil 6, adjusting the position of the second mold 44 or the mold 48, or adjusting the positions of a plurality of these. It will be done. For example, when the cathode foil 6 is fixed at the reference position, the distances Y1 and Y2 are adjusted by adjusting the position of the lead terminal 4. When the positions of the cathode foil 6 and the lead-out terminal 4 are fixed, the distances Z1 and Z2 are adjusted by adjusting the position of the second mold 44, particularly by adjusting the position of the mold end 45. The distances Y1 and Y2 and the distances Z1 and Z2 are basically the same before and after the process of connecting the lead terminals. Therefore, in the adjustment process of the stitch connection device 40, conditions (1) to (4) for the capacitor 2 can be used.

In the step of connecting the lead terminals, the lead terminals 4 are connected to each of the cathode foil 6 and the anode foil. In the process of connecting the lead terminal 4 to the cathode foil 6, a stitch connection device 40 is used. Stitch connection device 40 includes, for example, a first mold 42, a second mold 44, a stitch needle 46, and a mold 48. In the step of connecting the lead terminal 4 to the cathode foil 6, the lead terminal 4 is connected to the cathode foil 6 after the distances Y1, Y2 and distances Z1, Z2 have been adjusted.

As shown in FIG. 8A, the cathode foil 6 is placed on a first mold 42 such as a lower mold, and the lead terminals 4 are stacked on the upper surface of the cathode foil 6, that is, the terminal arrangement surface. A second mold 44 such as an upper mold is installed on the upper surface of the lead terminal 4. Therefore, the cathode foil 6 and the lead-out terminal 4 are sandwiched between the first mold 42 and the second mold 44 and held by the first mold 42 and the second mold 44. The cathode foil 6 placed on the first mold 42 is the cathode foil 6 before the through holes and the foil piece 28 are formed, and the lead-out terminal 4 placed on the cathode foil 6 is placed on the terminal hole 22. and the lead-out terminal 4 before the terminal piece 24 is formed.

The first mold 42 has a through hole 50 and the second mold 44 has a through hole 52. The through hole 50 has a hole shape that is slightly larger than the cross-sectional shape of the mold 48. The through hole 52 has a hole shape that is slightly larger than the cross-sectional shape of the stitch needle 46. The through hole 52 is smaller than the through hole 50 and is arranged directly above the through hole 50. The stitch needle 46 has, for example, a cylindrical shaft portion with an acute angle and a pyramidal tip portion, and is disposed above the through hole 52 .

The stitch needle 46 is lowered in the direction of the arrow shown in FIG. 8A, and as shown in FIG. 8B, the stitch needle 46 is inserted into the lead-out terminal 4 and the cathode foil 6 from the lead-out terminal 4 side. By inserting the stitch needle 46, a through hole and a foil piece 28 are formed in the cathode foil 6, and a terminal hole 22 and a terminal piece 24 are formed in the lead-out terminal 4. The lowered stitch needle 46 is raised and removed from the pull-out terminal 4 and the cathode foil 6.

The mold 48 has, for example, a flat pressing surface on the upper side, and is arranged below the through hole 50. The mold 48 is raised in the direction of the arrow shown in FIG. 8B, and the pressing surface presses the lead-out terminal 4 and the cathode foil 6, particularly the terminal piece 24 and the foil piece 28 from the cathode foil 6 side. As shown in FIG. 8C, the terminal piece 24 and the foil piece 28 are sandwiched between the second mold 44 and the mold 48. The terminal piece 24 and the foil piece 28 are folded back by pressing, and the lead terminal 4 is connected to the cathode foil 6. When the pressing surface presses the drawer terminal 4 and the cathode foil 6 from the cathode foil 6 side, press marks are formed on the drawer terminal 4 by the pressure of the second mold 44, and press marks are formed at the contact position of the mold end 45. An edge 32 is formed.

The process of connecting the lead terminal 4 to the anode foil may be the same as or different from the process of connecting the lead terminal 4 to the cathode foil 6. Since the anode foil does not have a carbon layer formed on its surface, it is less likely to be easily stretched by the stress generated by the pressing of the mold, unlike the cathode foil 6, which is a carbon layer-containing foil.

In the manufacturing process of the capacitor element, a first separator is placed between the anode foil and the cathode foil 6, and a second separator is placed outside the anode foil or the cathode foil 6. A capacitor element is produced by winding the anode foil, the cathode foil 6, and the first and second separators.

In the step of enclosing a capacitor element, a capacitor element impregnated with an electrolyte such as an electrolytic solution is inserted into an exterior case, and then a sealing member is attached to an opening of the exterior case to produce a capacitor 2.

According to the embodiment, for example, the following effects can be obtained.

(1) Foil cracking of the cathode foil 6 is suppressed by adjusting the protrusion, coincidence, or retraction of the press mark end 32 or the terminal end 34 of the drawer terminal 4, or by adjusting the distances Y1, Y2 or distances Z1, Z2. The connection between the terminal 4 and the cathode foil 6 can be stabilized.

(2) By adjusting the protrusion, coincidence, or retraction of the press mark end 32 or the terminal end 34, or by adjusting the distances Y1, Y2, or distances Z1, Z2, the foil ends 30, 31 are fixed when stress is generated in the cathode foil 6, Or the generated stress is widely distributed. In order to strengthen the connection of the easily stretchable cathode foil 6, even if the stress generated in the cathode foil 6 is greater than the stress of the cathode foil that does not include the carbon layer described above, it can be fixed by fixing the foil ends 30, 31 or dispersing the stress. Foil cracking can be suppressed. For example, the connection between the lead terminal 4 and the cathode foil 6 can be stabilized.

(3) By suppressing foil cracks, the risk of crack expansion due to vibration can be suppressed, and the vibration resistance of the capacitor 2 can be improved.

(4) By suppressing foil cracking, the reliability of the capacitor 2 can be improved.

(5) A stitch connection suitable for the properties of the cathode foil 6 including the carbon layer can be realized, and the stability or reliability of the capacitor 2 including the cathode foil 6 including the carbon layer can be improved.

(6) By sandwiching the periphery of the cathode foil 6 pressed by the molding die 48 between the first die 42 and the second die 44 and restraining the cathode foil 6, stress directed toward the outside of the carbon layer can be suppressed. can improve stability or reliability. In addition, as shown in FIG. 8, by sandwiching the corner of the lead terminal 4 between the first mold 42 and the second mold 44, the contact portion of the cathode foil 6 with the corner of the lead terminal 4 is provided with a mold It is possible to prevent stress from being propagated when pressed by 48. Therefore, cracks are less likely to occur at the contact portions of the cathode foil 6 with the corners of the lead-out terminals 4.

Characteristics and modifications of the embodiment described above are listed below.

(1) In the above embodiments, the capacitor element is a wound element. However, the capacitor element may be a laminated element in which a plurality of flat anode foils, cathode foils 6, and separators are laminated, for example.

(2) The materials for the anode foil, cathode foil 6, separator, exterior case, sealing member, and electrolyte are not limited to those described in the above embodiments. These materials may be other materials employed in aluminum electrolytic capacitors or similar capacitors. For example, a phenol laminate with external terminals attached may be used as the sealing member, or the above-mentioned capacitor element may be impregnated with electrolyte and then the lead-out terminal led out from the capacitor element may be connected to the external terminal of the sealing member. Often, the capacitor element and the sealing member may be inserted into an outer case and sealed with the sealing member.

(3) The material of the carbon layer is not limited to those described in the above embodiments. The material forming the carbon layer may be any conductive member containing carbon. Further, the state of adhesion or engagement of the carbon layer to the base foil is not limited to that described in the above embodiment.

(4) In the above embodiment, distances Y1 and Y2 and distances Z1 and Z2 are adjusted. However, only distances Z1 and Z2 may be adjusted. Foil cracking on the foil end 30 side can be suppressed by adjusting the distances Z1 and Z2.

(5) In the above embodiment, the shapes of the foil ends 30 and 31 and the terminal end 34 are almost unchanged except for the portion where cracks occur. However, the shapes of the foil ends 30, 31 and the terminal end 34 may change due to pressing in the process of connecting the lead-out terminals. As shown in FIG. 9, the foil end 31 and the terminal end 34 may swell outward, for example, by pressing in the process of connecting the drawer terminal. Even if the foil end 31 and the terminal end 34 swell outward, the position of the corner 54 of the terminal end 34 and the position of the foil end 31 near the corner 54 remain substantially unchanged. In other words, if the minimum distance between the corner portion 54 and the foil end 31 is measured as the distances Y1 and Y2, the distances Y1 and Y2 before and after the connecting process of the lead terminal can basically be made equal. Further, the foil end 30 and the press mark end 32 may bulge outward, for example, by pressing in the connecting process of the drawer terminal. Even if the foil end 30 and the press mark end 32 swell outward, the position of the corner of the press mark end 32 and the position of the foil end 30 near the corner remain substantially unchanged. In other words, if the minimum distance between the corner of the press mark end 32 and the foil end 30 is measured as the distances Z1 and Z2, the distances Z1 and Z2 before and after the connection process of the lead terminal can basically be made equal.

(6) In the above embodiment, the positions of both ends of the second mold 44 coincide with the positions of both ends of the mold 48 in the longitudinal direction of the extraction terminal 4. However, the positions of both ends or one end of the second mold 44 may be different from the positions of both ends or one end of the mold 48, and results similar to the first and second experimental results can be obtained. Be expected.

(7) In the above embodiment, the distances Y1 and Y2 and the distances Z1 and Z2 are adjusted by adjusting the stitch connection device 40. However, in order to adjust the distances Y1, Y2 or distances Z1, Z2, the foil width of the cathode foil 6 or the length of the flat portion 18 of the lead terminal 4 may be further adjusted. By increasing the number of adjustment items, the degree of freedom in adjustment can be increased.

(8) In the embodiment described above, the lead terminal 4 is placed on the cathode foil 6, the stitch needle 46 pierces the lead terminal 4 and the cathode foil 6 from above, and the mold 48 is inserted from below to pierce the lead terminal 4 and the cathode foil 6. 6 is pressed. However, it is only necessary that the relative arrangement of the extraction terminal 4, the cathode foil 6, the stitch needle 46, and the mold 48 be the same or similar. The lead terminal 4, the cathode foil 6, the stitch needle 46, and the mold 48 may be arranged upside down or rotated by an arbitrary angle relative to their arrangement in the embodiment, for example.

(9) In the embodiment described above, the stitch needle 46 is attached to the lead terminal 4 and the cathode foil 6 while both the cathode foil 6 and the lead terminal 4 are held between the first mold 42 and the second mold 44. Although the step of inserting the foil piece 28 and the terminal piece 24 through the process and the step of pressing the foil piece 28 and the terminal piece 24 with the mold 48 to form a stitched connection part were performed, the present invention is not limited thereto. For example, with both the cathode foil 6 and the lead terminal 4 held between the first mold 42 and the second mold 44, the stitch needle 46 is inserted through the lead terminal 4 and the cathode foil 6, and the foil pieces 28 and After the process of forming the terminal piece 24, the holding by the first mold 42 and the second mold 44 is released, and with the foil piece 28 and the terminal piece 24 formed, the cathode foil 6 and the lead-out terminal 4 are removed. It is sent to the next process, and pressed with a mold that has a flat pressing surface sandwiching the side of the cathode foil 6 on which the foil piece 28 and the terminal piece 24 are formed, and the side of the pull-out terminal 4 to form a stitched connection part. may be formed.

(10) In the above embodiment, the stitch needle 46 is attached to the lead terminal 4 and the cathode foil 6 while both the cathode foil 6 and the lead terminal 4 are held between the first mold 42 and the second mold 44. Although the step of forming the foil piece 28 and the terminal piece 24 by inserting the foil piece 28 is performed, the present invention is not limited thereto. For example, a through hole is formed in advance at the location where the through hole is to be formed using the stitch needle 46 of the cathode foil 6, and the lead terminal 4 is overlapped with the cathode foil 6 so as to cover the through hole, and then the cathode foil 6 and the lead terminal 4 are sandwiched and held between the first mold 42 and the second mold 44, and the stitch needle 46 is pulled out so that the terminal hole 22 is formed at a position that matches the through hole previously formed in the cathode foil 6. It may be inserted into the terminal 4. In this way, since a through hole is formed at the position where the stitch needle 46 is inserted into the cathode foil 6, the stitch needle 46 will not pierce the cathode foil 6, and the foil piece 28 will not be formed. Even if it is removed, a small foil piece 28 will be formed. Therefore, when the terminal piece 24 is pressed by the mold 48, the foil piece 28 is not present between the terminal piece 24 and the cathode foil 6 as in the above embodiment. As already mentioned, when a carbon layer is formed on the surface, the cathode foil 6 becomes easy to stretch. By not allowing the easily stretchable foil piece 28 to exist between the terminal piece 24 and the cathode foil 6, elongation due to pressing of the cathode foil 6 that overlaps with the foil piece 28 is suppressed, and the connection between the lead-out terminal 4 and the cathode foil 6 is improved. It can be stabilized. In this case, the stitch connection portion is a region where the terminal piece 24 is arranged, and refers to a region including a portion where the lead-out terminal 4 from the terminal hole 22, the cathode foil 6, and the terminal piece 24 are laminated.

As explained above, the most preferred embodiment of the present disclosure has been described, but the present disclosure is not limited to the above description, and the present disclosure is not limited to the inventions described in the claims or disclosed in the specification. It goes without saying that those skilled in the art can make various modifications and changes based on the gist of this disclosure, and it goes without saying that such modifications and changes are included within the scope of the present disclosure.

The technology of the present disclosure is useful because it can be used for connecting a cathode foil containing a carbon layer and an extraction terminal, and for a capacitor containing these.

2 Capacitor 4 Output terminal 6 Cathode foil 17 Metal wire 18 Flat part 22 Terminal hole 24 Terminal piece 28 Foil piece 30, 31 Foil end 32 Press mark end 34 Terminal end 36 Projecting foil end 38 Buffer area 40 Stitch connection device 42 First mold 44 second mold 45 mold end 46 stitch needle 48 mold 50, 52 through hole 54 corner

Claims (6)

a cathode foil including a carbon layer formed on the surface of the base foil;
an extraction terminal connected to the cathode foil by a stitch connection;
Equipped with
The lead terminal has a metal wire and a flat part connected to the cathode foil,
The press mark end formed on the metal wire side of the flat part by the stitch connection,
protrudes from the foil end of the cathode foil, or
coincident with said foil edge, or
A capacitor that overlaps the cathode foil at an interval of 0.1 mm or less from the end of the foil. The terminal end of the pull-out terminal is
protrudes from the other foil end of the cathode foil, or
coincident with said other foil edge, or
The capacitor according to claim 1, overlapping the cathode foil at an interval of 0.1 mm or less or 0.5 mm or more from the other foil end. A step of producing a lead terminal including a metal wire and a flat part;
A step of producing a cathode foil including a carbon layer formed on the surface of the base foil;
The flat part of the lead-out terminal is arranged on the cathode foil, and the end of the press mark that will be formed on the metal wire side of the flat part by pressing with a mold protrudes from the foil end of the cathode foil, or Pressing the lead-out terminal with the mold so that the edge of the press mark coincides with the edge of the foil, or so that the edge of the press mark overlaps the cathode foil at an interval of 0.1 mm or less from the edge of the foil. A method for manufacturing a capacitor, comprising the steps of: connecting the lead terminal to the cathode foil by stitch connection. In the step of connecting the extraction terminal to the cathode foil, the extraction terminal is connected to the cathode foil so that the terminal end of the extraction terminal protrudes from the other foil end of the cathode foil, or the extraction terminal is connected to the cathode foil. In the step of connecting to the cathode foil, the lead-out terminal is arranged such that the terminal end coincides with the other foil end or overlaps the cathode foil at an interval of 0.1 mm or less or 0.5 mm or more from the other foil end. 4. The method for manufacturing a capacitor according to claim 3, further comprising: connecting the cathode foil to the cathode foil. A method for manufacturing a capacitor comprising a cathode foil including a carbon layer, the method comprising:
A step of producing a lead terminal including a metal wire and a flat part;
so that the press mark end formed on the metal wire side of the flat part by the pressing of the mold protrudes from the foil end of the cathode foil, or so that the press mark end coincides with the foil end, or adjusting the stitch connection device so that the press mark edge overlaps the cathode foil at an interval of 0.1 mm or less from the foil edge;
A method for manufacturing a capacitor, comprising the steps of: connecting the lead-out terminal to the cathode foil by stitch connection using the adjusted stitch connection device, and forming the press mark end at the adjusted position. In the step of adjusting the stitch connection device, the stitch connection device is adjusted so that the terminal end of the drawer terminal protrudes from the other foil end of the cathode foil, or in the step of adjusting the stitch connection device, the step of adjusting the stitch connection device The stitch connection device is adjusted so that the terminal end coincides with the other foil end or overlaps the cathode foil at an interval of 0.1 mm or less or 0.5 mm or more from the other foil end. A method for manufacturing a capacitor according to claim 5.

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