WO2022092105A1

WO2022092105A1 - Method for manufacturing electrode foil for electrolytic capacitor, method for manufacturing electrolytic capacitor, and power supply device

Info

Publication number: WO2022092105A1
Application number: PCT/JP2021/039535
Authority: WO
Inventors: 満久吉村; 真佐美椿; 宗史門川
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2020-10-30
Filing date: 2021-10-26
Publication date: 2022-05-05
Also published as: CN116419992A; JPWO2022092105A1

Abstract

This method for manufacturing an electrode foil for an electrolytic capacitor involves an etching step in which an AC current is applied to a metal foil in an etching solution and an electrode foil having a porous part in the surface is obtained. The aforementioned AC current includes at least two mutually different waveforms.

Description

Manufacturing method of electrode foil for electrolytic capacitors, manufacturing method of electrolytic capacitors and power supply

The present invention relates to a method for manufacturing an electrode foil for an electrolytic capacitor, a method for manufacturing an electrolytic capacitor, and a power supply device.

The electrolytic capacitor is equipped with a capacitor element. As the anode body of the capacitor element, a metal foil containing a valve acting metal is used. In order to increase the capacity of the capacitor element, all or part of the main surface of the metal leaf is etched. Etching is performed by applying an alternating current to the metal foil in the etching solution.

Patent Documents

1 and 2 propose to make the waveform into a specific shape in an alternating current that repeats one type of waveform. Specifically, in Patent Document 1, the alternating current contains two half-waves having the same or different waveforms, amplitudes, and application times, or all of them, in the positive and negative half cycles. It is proposed to provide a rest period between each half wave in which the amplitude is 0 or the positive or negative side is applied with a minute current within 1/15 of the maximum amplitude. Patent Document 2 proposes that the waveform in a positive half cycle includes a portion in which the waveform greatly decreases from the peak time and a portion in which the waveform rises or falls gradually or gradually from immediately after the end of the decrease to the end of the half cycle. ..

Japanese Unexamined Patent Publication No. 7-235456 Japanese Unexamined Patent Publication No. 2007-123552

When an AC current is applied to the metal foil, the anodic reaction that melts the surface of the metal foil to form pits and the cathode reaction that forms a thin protective film on the surface of the metal foil and suppresses the melting of the surface are repeated alternately. Is done. The thickness of the protective film is non-uniform, and when an alternating current that repeats the same waveform is applied, pits are likely to be locally formed in the portion where the protective film is thin, and it is difficult to form pits uniformly on the metal foil surface. In

Patent Documents

1 and 2, an alternating current that repeats the same waveform is applied, and it is difficult to form pits uniformly.

One aspect of the present invention includes an etching step of applying an alternating current to a metal foil in an etching solution to obtain an electrode foil having a porous portion on the surface, and the alternating current has at least two types of waveforms different from each other. The present invention relates to a method for manufacturing an electrode foil for an electrolytic capacitor, including.

Another aspect of the present invention is a step provided in the above-mentioned method for manufacturing an electrode foil for an electrolytic capacitor, a step of covering the porous portion with a dielectric layer, and a step of covering at least a part of the dielectric layer with a solid electrolyte layer. It relates to a process and a method of manufacturing an electrolytic capacitor, including.

Yet another aspect of the present invention is a power supply device that applies an alternating current to the metal foil in the etching solution in the metal foil etching step, and includes an output unit that outputs the alternating current. It relates to a power supply device containing at least two types of waveforms that are different from each other.

According to the present invention, a good etching pit can be formed on the metal foil.

It is a graph which shows the case where an alternating current is a sine wave. It is a graph which shows the case where an alternating current is a triangular wave. It is a graph which shows an example of the waveform of the alternating current in the electrolytic etching process in the manufacturing method of the electrode foil for an electrolytic capacitor which concerns on one Embodiment of this invention. It is a graph which shows another example of the waveform of the alternating current in the electrolytic etching process in the manufacturing method of the electrode foil for an electrolytic capacitor which concerns on one Embodiment of this invention. It is a graph which shows still another example of the waveform of the alternating current in the electrolytic etching process in the manufacturing method of the electrode foil for an electrolytic capacitor which concerns on one Embodiment of this invention. It is explanatory drawing which shows typically the power-source device which concerns on one Embodiment of this invention. It is a graph which shows an example of the 1st waveform data stored in the waveform storage part of FIG. It is a graph which shows an example of the 2nd waveform data stored in the modulation storage part of FIG. It is a graph which shows another example of the 2nd waveform data stored in the modulation storage part of FIG. It is a graph which shows still another example of the 2nd waveform data stored in the modulation storage part of FIG. It is explanatory drawing which shows typically an example of the etching apparatus used in the etching process. It is sectional drawing which shows typically the capacitor element which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the electrolytic capacitor which concerns on one Embodiment of this invention.

Although the novel features of the invention are described in the appended claims, the invention is further described in detail with respect to both configuration and content, in conjunction with other objects and features of the invention, with reference to the drawings below. It will be well understood.

[Manufacturing method of electrode foil for electrolytic capacitors]
The method for producing an electrode foil according to an embodiment of the present invention includes an etching step of applying an alternating current to a metal foil in an etching solution to obtain an electrode foil having a porous portion on the surface. Alternating current includes at least two different waveforms that differ from each other. Note that the different waveforms here mean that the shape and / or magnitude of the waves are different.

By applying an alternating current containing at least two types of waveforms different from each other to the metal foil, the starting point where the pit is generated can be dispersed on the surface of the metal foil, and the pit is localized in the portion where the protective film is thin. The formation can be suppressed. That is, the pits can be formed more uniformly on the surface of the metal foil.

In the profile of current density with respect to time, one waveform has a period Tw and a fluctuation range, and includes a positive half period and a negative half period. The positive half-cycle shape and the negative half-cycle shape may have a point-symmetrical relationship with each other. The fluctuation range corresponds to the sum of the maximum value of the current density in the positive half cycle and the maximum value (absolute value) of the current density in the negative half cycle. The maximum values of the current densities existing in the positive and negative half cycles may be the same as each other. Examples of the wave shape include a sine wave shown in FIG. 1, a triangular wave shown in FIG. 2, a rectangular wave, and the like. In FIGS. 1 and 2, Im indicates the maximum value of the current density, and Tw indicates the period. In this case, 2 × Im corresponds to the fluctuation width, and Im corresponds to the amplitude.

At least two types of waveforms may have different fluctuation widths and / or periods from each other. At least two types of waveforms may differ from each other in the maximum value of the current density in the positive half cycle and / or the maximum value of the current density in the negative half cycle.

Further, at least two types of waveforms may have the same fluctuation width and period, and may have different shapes. For example, the timing at which the current density becomes maximum in one cycle may be different.

The alternating current is a modulated wave containing at least two types of waveforms that are different from each other, and the modulated wave may be repeated with a predetermined period Tm. The period Tm of the modulated wave is preferably a value obtained by summing the periods Tw of a plurality of waves (for example, 2 or more and 400 or less). When the wave period Tw is constant, the period Tm is preferably an integral multiple of the period Tw, and may be, for example, twice or more and 400 times or less of the period Tw, and may be twice or more and 100 times or less. May be good.

In the modulated wave, the fluctuation range may change periodically. The maximum value of the current density may be changed into a sinusoidal shape, a triangular wave shape, or a sawtooth wave shape, as shown in FIGS. 3 to 5 described later, for example. In this case, the period Tm of the modulated wave may be constant, and the fluctuation range may change periodically. In this case, from the viewpoint of efficiently forming the etching pits, the ratio of the minimum value A _min of the fluctuation width to the maximum value A _max of the fluctuation width: A _min / A _max may be 0.5 or more, and is 0. It may be 6.6 or more, or 0.7 or more. Further, from the viewpoint of forming a good etching pit, A _min / A _max may be 0.99 or less, 0.97 or less, or 0.9 or less. Regarding the range of A _min / A _max , the upper limit and the lower limit of the above A _min / A _max may be arbitrarily combined. For example, A _min / A _max may be 0.5 or more and 0.99 or less, 0.5 or more and 0.97 or less, and 0.6 or more and 0.97 or less. It may be 0.7 or more and 0.97 or less. The maximum value of the current density may be, for example, 5 A / cm ² or less. Further, when the pit is large, the maximum value of the current density may be 3 A / cm ² or less.

Further, in the modulated wave, the period Tw may be changed periodically. The frequency (1 / Tw) is preferably 3 Hz or higher and 65 Hz or lower, for example.

Here, FIGS. 3 to 5 are graphs showing examples of alternating current modulated waves in the electrolytic etching step in the method for manufacturing an electrode foil for an electrolytic capacitor according to an embodiment of the present invention, respectively.
In the graphs of FIGS. 3 to 5, the vertical axis is the current density. The modulated wave of FIGS. 3 to 5 is obtained by synthesizing the first waveform data shown in FIG. 7 with the second waveform data of FIGS. 8 to 10. The current density on the vertical axis of FIGS. 3 to 5 is represented as a relative value when the maximum value of the current density of the first waveform data of FIG. 7 is 1. The horizontal axis is time (seconds), and represents, for example, the time from the start of etching.

The alternating current shown in FIGS. 3 to 5 is a triangular wave, the period Tw is constant, and the fluctuation range changes periodically. The alternating current in FIG. 3 includes eight types of waveforms different from each other, the maximum value of the current density changes in a sinusoidal shape, and Tm is eight times Tw. In the alternating current of FIG. 3, the ratio of the minimum value A _min of the fluctuation width to the maximum value A _max of the fluctuation width: A _min / A _max is about 0.55.

The alternating current in FIG. 4 includes two types of waveforms having different fluctuation widths, the maximum value of the current density changes in a triangular wave shape, and Tm is twice Tw. In the alternating current of FIG. 4, the ratio of the minimum value A _min of the fluctuation width to the maximum value A _max of the fluctuation width: A _min / A _max is about 0.77.

The alternating current in FIG. 5 includes three types of waveforms having different fluctuation widths, the maximum value of the current density changes in a sawtooth shape, and Tm is three times Tw. In the alternating current of FIG. 5, the ratio of the minimum value A _min of the fluctuation width to the maximum value A _max of the fluctuation width: A _min / A _max is about 0.77.

Although triangular waves are shown in FIGS. 3 to 5, waves other than triangular waves such as sine waves may be used. In the alternating current shown in FIGS. 3 to 5, the types of waveforms are not limited to the above numbers. Tm / Tw is not limited to the above values. Tm / Tw is preferably 2 or more and 100 or less, and preferably 2 or more and 80 or less. 1 / Tm is preferably 0.2 Hz or more and 100 Hz or less, and more preferably 0.5 Hz or more and 50 Hz or less. In FIGS. 3 to 5, the frequency (1 / Tw) is about 24 Hz, but is not limited thereto. The frequency (1 / Tw) is, for example, 4 Hz or more and 60 Hz or less, preferably 5 Hz or more and 55 Hz or less. A _min / A _max is not limited to the above numerical values. In the case of the modulated wave of FIG. 3, A _min / A _max may be 0.55 or more and 0.99 or less, and may be 0.6 or more and 0.97 or less. In the case of the modulated wave of FIGS. 4 and 5, A _min / A _max may be 0.6 or more and 0.99 or less, and may be 0.7 or more and 0.97 or less.

(Etching process)
Etching of the metal leaf is performed by passing the above-mentioned AC current between the metal leaf and the electrode in the etching solution with the electrode facing the at least one main surface of the metal leaf. Etching may be performed on only one main surface of the metal leaf or on both main surfaces. The current density and etching time of the alternating current are not particularly limited, and may be appropriately set according to the thickness of the electrode foil, the desired depth of the etching pit, and the like.

The average current density of the alternating current applied in the etching step may be constant. In this case, the average current density of the alternating current is, for example, 0.05 A / cm ² or more and 1.7 A / cm ² or less, preferably 0.08 A / cm ² or more and 1.2 A / cm ² or less. The average current density is obtained by dividing the integrated value of the current density by the time in the current density profile with respect to time. When the period Tm of the modulated wave is constant, the integrated value of the current density in the period Tm is obtained, and the integrated value is divided by Tm to obtain the integrated value. For example, in the case of the sine wave of FIG. 1 (the maximum value of the current density is Im), the average current density is (2 / π) × Im. In the case of the triangular wave of FIG. 2 (the maximum value of the current density is Im), the average current density is 1/2 × Im.

In the etching process, the etching of the metal foil may be performed intermittently. In other words, the electrolytic etching step preferably has an electroless time. As a result, the diffusion of metal ions derived from the metal foil generated in the etching pit is promoted, and the etching efficiency is easily improved. The electroless time is, for example, the time for the metal foil to move between the electrodes when there are a plurality of electrodes, and the time for the metal leaf to move between the etching tanks when there are a plurality of etching tanks.

The electroless time may also be a cleaning step of cleaning the metal leaf. Pure water (ion-exchanged water) is preferably used for cleaning the metal foil. This is because impurities are removed and the metal ions are more easily diffused. The cleaning step may be performed during the etching.

(Metal leaf)
The metal leaf contains valve acting metals such as titanium, tantalum, aluminum and niobium. The metal leaf contains one or more of the above valve acting metals. The metal leaf may contain the above-mentioned valve acting metal in the form of an alloy or an intermetallic compound. The thickness of the metal foil is not particularly limited. The thickness of the metal foil is, for example, 10 μm or more and 300 μm or less. When the metal foil is used as the anode foil, the thickness of the metal foil is preferably 60 μm or more and 250 μm or less. When the metal foil is used as the cathode foil, the thickness of the metal foil is preferably 10 μm or more and 80 μm or less.

(Etching liquid)
As the etching solution, a known etching solution used for electrolytic etching can be used. Examples of the etching solution include an aqueous solution containing sulfuric acid, nitric acid, phosphoric acid and / or oxalic acid and hydrochloric acid. The aqueous solution may contain various additives such as a chelating agent. The concentration of hydrochloric acid in the etching solution, the concentration of other acids, and the temperature are not particularly limited, and may be appropriately set according to the desired shape of the etching pit and the performance of the capacitor. The concentration of hydrochloric acid in the etching solution is, for example, 1 mol / L or more and 10 mol / L or less. The concentration of other acids in the etching solution is, for example, 0.01 mol / L or more and 1 mol / L or less. The temperature of the etching solution during the electrolytic etching step is not particularly limited, and is, for example, 5 ° C. or higher and 60 ° C. or lower.

[Power supply]
The power supply device according to an embodiment of the present invention includes an output unit that outputs an alternating current with respect to a power supply device that applies an alternating current to the metal foil in the etching solution in the metal foil etching step, and the alternating currents are mutually exclusive. Includes at least two different waveforms.

Here, FIG. 6 is a configuration diagram schematically showing an example of a power supply device that outputs an alternating current.
The power supply device 200 shown in FIG. 6 has a waveform storage unit 201 that stores the first waveform data of the first alternating current, a modulation storage unit 202 that stores the second waveform data that modulates the first waveform data, and a first waveform. It includes a synthesis unit 203 that synthesizes data and a second waveform data, and an output unit 204 that outputs an alternating current as a modulated wave based on the synthesis data synthesized by the synthesis unit 203. The second waveform data is data indicating the degree of modulation of the current density (maximum value), fluctuation width, period, etc. with respect to the first waveform data.

The waveform storage unit 201 stores, for example, the first waveform data of the first alternating current shown in FIG. 7. FIG. 7 shows waveform data in which a constant triangular wave is repeated. In the graph shown in FIG. 7, the vertical axis represents the current density, and is represented as a relative value with the maximum value of the current density being 1. The horizontal axis is time (seconds).

The modulation storage unit 202 stores, for example, the second waveform data shown in FIGS. 8 to 10. In the graphs shown in FIGS. 8 to 10, the horizontal axis is time (seconds). Further, the vertical axis represents the degree of modulation, which indicates the degree of modulation of the current density of the first waveform data in FIG. 7.

When the second waveform data shown in FIG. 8 is used, when the current density of the first waveform data is I and the modulation degree is f at an arbitrary time, the current density after modulation is I × (1 + a × f). It becomes. The degree of modulation varies from -1 to 1 in a sinusoidal manner. a is a coefficient, and is set in the range of, for example, 0.01 to 0.3. When the degree of modulation f is 0, the current density is the same as the current density in FIG. 7. When the degree of modulation f is 1 and the coefficient a is 0.3, the current density (absolute value) is 30% larger than the current density (absolute value) of the first waveform data in FIG. 7. When the degree of modulation f is -1 and the coefficient a is 0.3, the current density (absolute value) is 30% smaller than the current density (absolute value) of the first waveform data in FIG. 7. When the coefficient a is 0.3, the modulated wave of FIG. 3 is obtained.

When the second waveform data shown in FIGS. 9 and 10 is used, when the current density of the first waveform data is I and the degree of modulation is f at an arbitrary time, the current density after modulation is I × (1 + a). × | f |). In the positive half cycle, the degree of modulation varies between 0 and 1, and in the negative half cycle, the degree of modulation varies between -1 and 0. a is a coefficient, and is set in the range of, for example, 0.01 to 0.3. When the degree of modulation f is 0, the current density is the same as the current density in FIG. 7. In the positive half cycle, when the modulation factor f is 1 and the coefficient a is 0.3, the current density is 30% larger than the current density of the first waveform data (positive half cycle) in FIG. 7. In the negative half cycle, when the degree of modulation f is -1 and the coefficient a is 0.3, the current density (absolute value) with respect to the current density (absolute value) of the first waveform data (negative half cycle) in FIG. Absolute value) increases by 30%. When the coefficient a is 0.3, the modulated wave of FIGS. 4 and 5 is obtained.

When the first waveform data shown in FIG. 7 and the second waveform data (coefficient a = 0.3) shown in FIG. 8 are combined, the alternating current is output as the modulated wave shown in FIG. When the first waveform data shown in FIG. 7 and the second waveform data (coefficient a = 0.3) shown in FIG. 9 are combined, the alternating current is output as the modulated wave shown in FIG. When the first waveform data shown in FIG. 7 and the second waveform data (coefficient a = 0.3) shown in FIG. 10 are combined, the alternating current is output as the modulated wave shown in FIG.

The fluctuation width of the modulated wave changes periodically, and the ratio of the minimum fluctuation width A _min to the maximum fluctuation width A _max : A _min / A _max may be within the above range, and is 0. It may be 5.5 or more and 0.97 or less. In this case, good etching pits can be efficiently formed.

Although the waveform storage unit and the modulation storage unit are provided inside the power supply device in FIG. 6, they may be provided outside the power supply device.

Further, the power supply device is divided into a synthesis unit that synthesizes the first waveform data of the first alternating current and the second waveform data of the second alternating current whose waveform is different from that of the first alternating current, and the composite data synthesized by the synthesis unit. Based on this, an output unit that outputs an alternating current as a modulated wave may be provided. The first alternating current and the second alternating current have different periods or periods and fluctuation ranges from each other, for example. The power supply device may include a storage unit that stores waveform data of the first alternating current and the second alternating current. The storage unit may be provided outside the power supply device.

[Etching equipment]
FIG. 11 is an explanatory diagram schematically showing an example of an etching apparatus used in the etching process. The etching apparatus 20 includes an etching tank 23 for holding an etching solution, a plurality of transport rolls 25 for transporting the metal foil 10, a pair of electrodes 22 facing the metal foil 10, and an AC power supply 24 for passing a current through the electrodes 22. , Equipped with. As the AC power supply 24, the above power supply device (for example, the power supply device 200) is used. The metal leaf 10 moves in the etching tank 23 while being conveyed via the plurality of conveying rolls 25. The metal leaf 10 is etched while facing the electrode 22 in the etching tank 23. As a result, the electrode foil 11 is obtained.

FIG. 11 shows a case where etching is performed on a long metal foil, but the present invention is not limited to this. For example, etching may be performed on a metal leaf having a certain area that has been stationary. Further, in FIG. 11, a pair of electrodes is used, but the present invention is not limited to this. For example, the metal leaf may be opposed to one electrode, and the electrode and the metal leaf may be connected to an AC power source for etching. Further, there may be a plurality of etching tanks. There may be two or more pairs of electrodes in one etching tank.

Further, the etching device may be provided with a plurality of power supply devices. For example, the etching apparatus may include a plurality of etching tanks, and a power supply device may be connected to each of the plurality of etching tanks. In this case, at least one of the plurality of power supply devices may output an alternating current as a modulated wave, and it is preferable that 20% or more of the plurality of power supply devices output an alternating current as a modulated wave. For example, when a power supply device is connected to each of 10 or more etching tanks, it is preferable that two or more power supply devices output an alternating current as a modulated wave.

[Manufacturing method of electrolytic capacitors]
The method for manufacturing an electrolytic capacitor according to an embodiment of the present invention includes a step (etching step) provided in the above-mentioned method for manufacturing an electrode foil for an electrolytic capacitor, a step of covering a porous portion with a dielectric layer, and a dielectric layer. It comprises a step of covering at least a part with a solid electrolyte layer.

(Dielectric layer forming process)
The dielectric layer may contain oxides of the valve acting metal. For example, when aluminum is used as the valve acting metal, the dielectric layer may contain Al ₂ O ₃ . The dielectric layer is formed by, for example, anodizing the surface of an anode body (the above-mentioned electrode foil) by chemical conversion treatment or the like. The dielectric layer is not limited to this, and may be any one that functions as a dielectric. The dielectric layer may be formed so as to cover at least a part of the surface of the anode. The dielectric layer is formed along the inner wall surface of the pores and pits of the porous portion of the electrode foil.

(Step of forming solid electrolyte layer)
The solid electrolyte layer contains, for example, a manganese compound or a conductive polymer. The solid electrolyte layer containing the conductive polymer can be formed, for example, by chemically polymerizing and / or electrolytically polymerizing the raw material monomer on the dielectric layer. Alternatively, it can be formed by applying a solution in which the conductive polymer is dissolved or a dispersion liquid in which the conductive polymer is dispersed to the dielectric layer. As the conductive polymer, polypyrrole, polyaniline, polythiophene, polyacetylene, derivatives thereof and the like can be used. The solid electrolyte layer may contain a dopant such as polystyrene sulfonic acid together with the conductive polymer. The solid electrolyte layer may further contain additives, if necessary.

(Cathode lead-out layer forming process)
The method for manufacturing an electrolytic capacitor may further include a step of covering the solid electrolyte layer with a cathode extraction layer. In this way, a capacitor element including an electrode foil, a dielectric layer, a solid electrolyte layer, and a cathode extraction layer may be formed. The cathode extraction layer may be formed so as to cover at least a part of the solid electrolyte layer, or may be formed so as to cover the entire surface of the solid electrolyte layer. The cathode extraction layer has, for example, a carbon layer and a metal (for example, silver) paste layer formed on the surface of the carbon layer. The carbon layer is composed of a composition containing a conductive carbon material such as graphite. The metal paste layer is composed of, for example, a composition containing silver particles and a resin. The configuration of the cathode extraction layer is not limited to this, and may be any configuration having a current collecting function.

FIG. 12 is a cross-sectional view schematically showing the capacitor element according to the present embodiment. The capacitor element 110 is in the form of a sheet. The anode portion 110a is composed of an electrode foil (anode body) 11. The cathode portion 110b includes an anode body 11, a dielectric layer 12, and a cathode layer 13. The cathode layer 13 has a solid electrolyte layer 13a and a cathode extraction layer 13b.

[Electrolytic capacitor]
The capacitor element constitutes an electrolytic capacitor. The electrolytic capacitor may include a plurality of capacitor elements. In the electrolytic capacitor, a plurality of capacitor elements may be laminated. The number of laminated capacitor elements is not particularly limited, and is, for example, 2 or more and 20 or less.

The anode parts of the laminated capacitor elements are joined by welding and / or caulking, etc., and are electrically connected. An anode lead terminal is bonded to the anode portion of at least one capacitor element. The plurality of anode portions are crimped by, for example, bent anode lead terminals. The anode portion and the anode lead terminal may be further laser welded. This improves the connection reliability between the plurality of anode portions and the connection reliability between the anode portions and the anode lead terminals.

The cathode parts of the laminated capacitor elements are also electrically connected to each other. A cathode lead terminal is bonded to the cathode layer of at least one capacitor element. The cathode lead terminal is bonded to the cathode layer via, for example, a conductive adhesive.

The capacitor element is sealed with an insulating material so that at least a part of the anode lead terminal and the cathode lead terminal is exposed. Examples of the insulating material include a cured product of a thermosetting resin and engineering plastics. Examples of the thermosetting resin include epoxy resin, phenol resin, silicone resin, melamine resin, urea resin, alkyd resin, polyurethane, and unsaturated polyester. Engineering plastics include general purpose engineering plastics and super engineering plastics. Examples of engineering plastics include polyimide and polyamide-imide.

FIG. 13 is a cross-sectional view schematically showing an electrolytic capacitor according to this embodiment. The electrolytic capacitor 100 includes one or more capacitor elements 110, an anode lead terminal 120A bonded to the anode portion 110a of the capacitor element 110, a cathode lead terminal 120B bonded to the cathode portion 110b, and insulation for sealing the capacitor element. The material 130 is provided.

In the present embodiment, an electrolytic capacitor in which a solid electrolyte is used as an electrolyte and the capacitor element is sealed with an insulating material is mentioned, but the present invention is not limited to this. The electrode foil according to the present embodiment can be applied to, for example, an electrolytic capacitor having an anode and a cathode formed of a strip-shaped electrode foil wound around a separator and an electrolytic solution. In this case, the electrode foil according to this embodiment is used for at least one of the anode and the cathode. In particular, the electrode foil according to the present embodiment is preferably used for the anode of a large-capacity laminated electrolytic capacitor or a wound electrolytic capacitor. When the electrolytic capacitor includes a plurality of capacitor elements, each capacitor element may be of a winding type.

[Example]
Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to Examples.

<< Examples 1 to 3 >>
An aluminum foil having a thickness of 100 μm and a purity of 99.98% was prepared. This aluminum foil was immersed in an aqueous solution having a phosphoric acid concentration of 1.0% by mass and 90 ° C. for 60 seconds for pretreatment.

Subsequently, electrolytic etching was performed as follows using an etching apparatus as shown in FIG. As the etching solution, an aqueous solution containing 5% by mass of hydrochloric acid, 2% by mass of aluminum chloride, 0.1% by mass of sulfuric acid, 0.5% by mass of phosphoric acid, and 0.2% by mass of nitric acid was used, and the solution temperature was 35 ° C. The etching time was 5 minutes.

The power supply device shown in FIG. 6 was used as the AC power supply. The first waveform data and the second waveform data (coefficient a = 0.3) were combined, and the alternating current was output as a modulated wave. The waveform data shown in Table 1 was used for the first waveform data and the second waveform data, and the modulated waves shown in Table 1 were obtained.

The etching time was 2 minutes. The frequency of the alternating current (1 / Tw) was set to about 24 Hz. The average current density of the alternating current was constant and was set to 0.2 A / cm ² .

The aluminum foil was immersed in an aqueous solution at 60 ° C. containing 10% by mass of sulfuric acid for 60 seconds, and then heat-treated at 250 ° C. for 120 seconds to prepare an electrode foil for an electrolytic capacitor. Further, by anodizing, a dielectric layer containing aluminum oxide (Al ₂ O ₃ ) was formed on the surface of the electrode foil.

<< Comparative Example 1 >>
An electrode foil was obtained in the same manner as in Example 1 except that the first alternating current of the first waveform data was output as it was without synthesizing the first waveform data and the second waveform data. By anodizing, a dielectric layer containing aluminum oxide (Al ₂ O ₃ ) was formed on the surface of the electrode foil.

For the electrode foil (anode) having a dielectric layer on the surfaces of Examples 1 to 3 and Comparative Example 1, a test method for an electrode foil for an aluminum electrolytic capacitor of RC-2364A of the Japan Electronic Machinery Manufacturers Association (EIAJ) standard (EIAJ). The capacitance was measured based on the type of foil, which is an anodized foil for medium and high pressure. As a result, it was confirmed that in Examples 1 to 3, the capacitance increased by about 15% as compared with Comparative Example 1.

Although the present invention has been described with respect to preferred embodiments at this time, such disclosure should not be construed in a limited way. Various modifications and modifications will undoubtedly become apparent to those skilled in the art belonging to the present invention by reading the above disclosure. Accordingly, the appended claims should be construed to include all modifications and modifications without departing from the true spirit and scope of the invention.

Since the electrode foil manufactured by the method according to the present invention can realize a high capacitance, it can be used as a capacitor for various purposes.

200: Power supply device 201: Waveform storage unit 202: Modulation storage unit 203: Synthesis unit 204: Output unit 20: Etching device 22: Electrode 23: Etching tank 24: AC power supply 25: Conveyance roll 10: Metal leaf 11: Electrode foil ( Anode)
100: Electrolytic capacitor 110: Condenser element 110a: Anode portion 110b: Cathode portion 12: Dielectric layer 13: Cathode layer 13a: Solid electrolyte layer 13b: Cathode extraction layer 120A: Anode lead terminal 120B: Cathode lead terminal 130: Insulation material

Claims

It includes an etching step of applying an alternating current to a metal foil in an etching solution to obtain an electrode foil having a porous portion on the surface.
A method for manufacturing an electrode foil for an electrolytic capacitor, wherein the alternating current includes at least two types of waveforms different from each other.
The method for manufacturing an electrode foil for an electrolytic capacitor according to claim 1, wherein at least one of the fluctuation width and the period of the at least two types of waveforms is different from each other.
The alternating current is a modulated wave including the at least two types of waveforms.
The method for manufacturing an electrode foil for an electrolytic capacitor according to claim 2, wherein the modulated wave is repeated at a predetermined cycle.
The fluctuation range of the modulated wave is changing periodically,
The electrode foil for an electrolytic capacitor according to claim 3, wherein the ratio of the minimum value A min of the fluctuation width to the maximum value A max of the fluctuation width: A min / A max is 0.5 or more and 0.97 or less. Manufacturing method.
The step provided in the method for manufacturing an electrode foil for an electrolytic capacitor according to any one of claims 1 to 4.
The step of covering the porous portion with a dielectric layer and
A step of covering at least a part of the dielectric layer with a solid electrolyte layer,
How to manufacture electrolytic capacitors, including.
A power supply that applies an alternating current to the metal leaf in the etching solution in the metal leaf etching process.
It is equipped with an output unit that outputs the alternating current.
A power supply device in which the alternating current contains at least two types of waveforms that are different from each other.
A waveform storage unit that stores the first waveform data of the first alternating current,
A modulation storage unit that stores the second waveform data that modulates the first waveform data,
A compositing unit that synthesizes the first waveform data and the second waveform data,
Based on the synthetic data synthesized by the synthesis unit, the output unit that outputs the alternating current as a modulated wave and the output unit.
The power supply device according to claim 6.
The fluctuation range of the modulated wave is changing periodically,
The power supply device according to claim 7, wherein the ratio of the minimum value A min of the fluctuation width to the maximum value A max of the fluctuation width: A min / A max is 0.5 or more and 0.97 or less.
A compositing unit that synthesizes the first waveform data of the first alternating current and the second waveform data of the second alternating current whose waveform is different from that of the first alternating current.
Based on the synthetic data synthesized by the synthesis unit, the output unit that outputs the alternating current as a modulated wave and the output unit.
The power supply device according to claim 6.