JPH11154626A - Method and device of manufacture of electrode foil for aluminum electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device of manufacture of an electrode foil for a high quality and highly reliable aluminum electrolytic capacitor having no deposition of copper. SOLUTION: A change-over switch 14, which switches polarity of chemical formation DC power source 11 applying a DC current to aluminum foil 13 and a chemical reaction cathode plate 12 in a chemical reaction vessel 4, is provided, and growth of copper deposited on a chemical formation cathode plate 12 can be blocked and the deposition of copper on the aluminum foil 13 can be prevented by applying reverse polarity voltage for a prescribed time at the prescribed interval while chemical formation is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electrode foil for an aluminum electrolytic capacitor used for manufacturing an electrode foil which is a main component of an aluminum electrolytic capacitor used for various electronic devices, and an apparatus for manufacturing the same. It is.

[0002]

2. Description of the Related Art As electronic devices have been reduced in size and performance, aluminum electrolytic capacitors have also been required to be reduced in size and performance. High capacity and high reliability have become important technologies, and etching technology to increase the surface area of the electrode foil, and improvement of the quality of the oxide film formed on the surface of the electrode foil are particularly important technical issues. In the case of foil, removal of copper remaining on the electrode foil surface after etching, which has a significant effect on product reliability, is an important technical issue in addition to capacity improvement. On the other hand, it was a fact that they were competing.

[0003] A method and an apparatus for manufacturing such a conventional electrode foil for an aluminum electrolytic capacitor will be described below with reference to the drawings.

FIG. 2 is a conceptual diagram showing the structure of a conventional apparatus for manufacturing an electrode foil for an aluminum electrolytic capacitor. In FIG. 2, reference numeral 1 denotes an unwinding roll for supplying an aluminum foil wound in a roll shape; Pretreatment tank, 3 is an etching tank,
4 is a chemical conversion tank, 5 is a copper removal tank, 6 is a post-treatment tank, 7 is a drying furnace,
8 is a take-up roll, 9 is an etching cathode plate, 10 is a DC power source for etching, 11 is a DC power source for formation, 12 is a formation cathode plate, and 13 is an aluminum foil.

[0005] An example in which an alloy-based cathode foil for an aluminum electrolytic capacitor is manufactured using the apparatus for manufacturing an electrode foil for an aluminum electrolytic capacitor thus configured will be described below.

First, copper is used as the aluminum foil 13.
A surface having a thickness of 20 to 50 μm containing 1 to 1% is cleaned with an alkali or acid-based treatment liquid in the pretreatment tank 2. Next, the pretreated aluminum foil 13 is transported to the etching bath 3 and immersed in a hydrochloric acid-based etching solution containing a small amount of impurities such as sulfuric acid, nitric acid, and phosphoric acid and heated to 70 to 90 ° C. I do.

At this time, the aluminum foil 13 is used as a positive electrode,
By applying a DC current from an etching DC power supply 10 with the etching cathode plate 9 arranged in parallel on both sides of the aluminum foil 13 as a negative electrode, the aluminum foil 13
An etching step is performed to increase the surface area by chemically and electrically etching the surface of the substrate. In this etching step, aluminum and copper are dissolved in the etching solution and exist as aluminum ions and copper ions, and some of the copper ions in the etching solution are electrically collected on the etching cathode plate 9. Is deposited as metallic copper, and a part of the remaining copper ions is
Deposited on the surface of the substrate and carried to the next step.

Next, the etched aluminum foil 13 is conveyed to a chemical conversion tank 4, where the aluminum foil 13 is subjected to 60-70.
The aluminum foil 13 is used as a positive electrode in a chemical solution heated to 0 ° C., and a direct current is applied by a direct-current power source 11 for formation using a negative electrode 12 formed in parallel with both sides of the aluminum foil 13 as a negative electrode. Chemical formation is performed in which a thin oxide film is formed by anodic oxidation between 13 and copper deposited on the surface of aluminum foil 13.

Thereafter, the aluminum foil 13 after the formation is formed.
Is transferred to a copper removal tank 5, and the aluminum foil 13 is immersed in an acid solution heated to 40 to 50 ° C. in the copper removal tank 5 to dissolve copper precipitated on the surface of the aluminum foil 13. After the removal, a post-treatment in a post-treatment tank 6 and a drying step in a drying furnace 7 were taken up on a take-up roll 8 to produce an alloy-based cathode foil for an aluminum electrolytic capacitor.

[0010]

However, in the above-mentioned conventional method for manufacturing an electrode foil for an aluminum electrolytic capacitor, a thin oxide film is formed between the aluminum foil 13 and copper deposited on the surface of the aluminum foil 13 by anodic oxidation. During the formation, a part of the copper deposited on the surface of the aluminum foil 13 is ionized and diffuses into the formation solution to form the copper plate 12.
Copper deposited again on the cathode plate 12 and grown on the cathode plate 12 grows with time, becomes thicker by long-time operation, detaches from the cathode plate 12, and floats in the formation solution. . If the copper floating in the chemical conversion solution adheres to the aluminum foil 13 and is brought to the product without removing the copper in a later process, the product may cause a short-circuit failure, and the reliability of the product is reduced. There was a problem of lowering.

The present invention solves such a conventional problem,
Aluminum that can prevent the growth of copper deposited on the chemical conversion cathode plate and can produce a high-quality and highly reliable electrode foil without copper floating in the chemical conversion solution and no adhesion of copper An object of the present invention is to provide a method for manufacturing an electrode foil for an electrolytic capacitor and an apparatus for manufacturing the same.

[0012]

In order to solve the above-mentioned problems, a method for manufacturing an electrode foil for an aluminum electrolytic capacitor according to the present invention comprises: an etching step for enlarging the surface area of an aluminum foil containing at least a trace amount of impurities; An oxide film forming step of forming an oxide film on the surface of the aluminum foil by anodic oxidation, and a copper removing step of removing copper deposited on the surface of the aluminum foil, A copper dissolving step of applying a voltage having a polarity opposite to the polarity of the applied voltage to the aluminum foil for a predetermined time is provided at predetermined intervals in the oxide film forming step. The manufacturing apparatus has a configuration in which a polarity switching unit that switches the polarity of a DC power supply that applies a DC current to the aluminum foil and the formation cathode plate is provided in the oxide film forming unit.

According to this method, it is possible to prevent the growth of copper deposited on the formation cathode plate, and to prevent the copper from floating in the formation solution and to prevent the adhesion of copper. Can be manufactured.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides an etching step for enlarging the surface area of an aluminum foil containing at least a trace amount of impurities, and forming an oxide film on the surface of the etched aluminum foil by anodic oxidation. An oxide film forming step to be formed, and a copper removing step of removing copper deposited on the surface of the aluminum foil, having a polarity opposite to the polarity of the voltage applied to the aluminum foil during anodic oxidation in the oxide film forming step. A copper dissolving step of applying a voltage to the aluminum foil for a predetermined time is provided at predetermined intervals in the oxide film forming step, and according to this manufacturing method,
The copper deposited on the formation cathode plate during the anodic oxidation in the oxide film formation step is dissolved by applying a voltage of the opposite polarity to the formation cathode plate, thereby preventing the growth of copper and preventing the copper from floating in the formation solution. It has the effect that it can be eliminated.

According to a second aspect of the present invention, in the first aspect of the present invention, the aluminum foil is an alloy-based cathode foil, and has the same function as that of the first aspect of the invention. Have.

According to a third aspect of the present invention, in the first aspect of the present invention, the impurity is copper.
It has the same operation as the operation according to the first aspect of the present invention.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the aluminum foil is supplied as a roll-shaped product obtained by continuously joining a plurality of roll-shaped products having a predetermined length,
In addition, a copper dissolving process is performed when the joint portion of the roll-shaped article passes through the oxide film forming process.In order to perform the copper dissolving process at the joint portion not used as a product, aluminum is formed by chemical conversion. This has the effect of stabilizing the quality without affecting the state of the oxide film formed on the surface of the foil.

According to a fifth aspect of the present invention, there is provided an unwinding section for supplying a rolled aluminum foil, an etching tank for immersing the aluminum foil supplied from the unwinding section in an etching solution, and A DC current is applied from a DC power supply for etching in which an aluminum foil immersed in an etching solution in a tank is connected to a positive electrode, and an etching cathode plate disposed opposite to both surfaces of the aluminum foil in the etching solution is connected to a negative electrode. An etching section for chemically and electrically etching the surface of an aluminum foil by means of an aluminum foil having a chemical conversion tank for immersing the etched aluminum foil in a chemical conversion liquid, and immersed in a chemical conversion liquid in the chemical conversion tank Is connected to the anode and the cathode is connected to the anode and the cathode is placed on both sides of the aluminum foil in the chemical solution. An oxide film is formed between the aluminum foil and the copper deposited on the aluminum foil by applying a DC current from a power supply, and a DC current is applied to the aluminum foil and the cathode plate at the oxide film formation portion. A polarity switching unit for switching the polarity of the DC power supply to be applied, and a copper removal tank for immersing the aluminum foil on which the oxide film is formed in the oxide film formation unit in an acid solution, and in the copper removal tank, It consists of a copper removal part that dissolves and removes the copper deposited on the surface of the foil, and a winding part that winds up the aluminum foil that has passed through the copper removal part into a roll shape. The copper deposited on the plate is dissolved by applying a voltage of the opposite polarity to the formation cathode plate to prevent the growth of copper and to prevent the copper from floating in the formation solution. It has the effect of say.

According to a sixth aspect of the present invention, in the fifth aspect of the invention, a pair of electrodes connected to a DC power supply are arranged in a chemical solution circulating in a chemical conversion tank. In addition, since copper dissolved in the chemical conversion solution can be deposited on the negative electrode plate of the pair of electrodes and removed, copper has an effect of preventing floating in the chemical formation solution.

An embodiment of the present invention will be described below with reference to the drawings. Components having the same configuration as the components described in the section of the related art are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a conceptual diagram showing the configuration of an apparatus for manufacturing an electrode foil for an aluminum electrolytic capacitor according to the embodiment.
In the figure, 1 is an unwinding roll, 2 is a pretreatment tank, 3
Is an etching tank, 4 is a formation tank, 5 is a copper removal tank, 6 is a post-treatment tank, 7 is a drying furnace, 8 is a take-up roll, 9 is an etching cathode plate, 10 is a DC power supply for etching, and 11 is a DC for formation. A power supply, 12 is a chemical cathode plate, and 13 is an aluminum foil. The above configuration is the same as that of FIG. 2 described in the section of the prior art.

Reference numeral 14 denotes a changeover switch. The changeover switch 14 is provided so that the polarity of the DC voltage output from the formation DC power supply 11 can be switched between A side and B side in the figure. The DC voltage output from the power supply 11 is connected via the changeover switch 14 so as to be applied to the formation cathode plate 12 and the aluminum foil 13.

Next, an example in which an alloy-based cathode foil for an aluminum electrolytic capacitor is manufactured using the apparatus for manufacturing an electrode foil for an aluminum electrolytic capacitor of the present embodiment having the above-described configuration will be described. This will be described below.

First, as the aluminum foil 13, 0.3%
The aluminum foil 13 is transported at a feed speed of about 10 m / min using a 50 μm-thick roll-shaped product containing copper and a small amount of iron, and the etching is uniformly performed except for the rolling oil and the natural oxide film on the surface. To perform the pretreatment, the aluminum foil 13 was immersed in the treatment liquid in the pretreatment tank 2 containing 2% sodium hydroxide at a liquid temperature of 50 ° C. for 10 seconds to perform the pretreatment.

Subsequently, the aluminum foil 13 is washed with water and conveyed to the etching tank 3 and contains a small amount of sulfuric acid.
% Of hydrochloric acid at the same time as the immersion in an etching solution at a temperature of 80 ° C., and at the same time, a DC power supply 10
Current of 0.1 A / cm ² to the aluminum foil 13
Chemical and electrolytic etching was performed by flowing for 2 seconds.

In this etching step, the aluminum in the aluminum foil 13 dissolves in the etching solution as aluminum ions and the aluminum foil 13
The copper contained in is also dissolved in the etching solution as copper ions,

[0027]

Embedded image

Since the reaction proceeds to the left, the aluminum foil 1
The copper ions existing near the interface between 3 and the etching solution oxidize the aluminum and reduce itself to form metallic copper, which is deposited on the surface of the aluminum foil 13.

Subsequently, the etched aluminum foil 13 is washed with water, transported to a chemical conversion tank 4, and contained in a chemical solution containing 10% adipic acid and having a temperature of 70 ° C., and a DC power source 11 for chemical formation. The aluminum foil 13 is used as a positive electrode while the changeover switch 14 of the
By performing formation at a formation voltage of 5 V using 2 as a negative electrode,
An oxide film is formed between the aluminum foil 13 and copper deposited on the aluminum foil 13 to prevent exchange of electric charge due to reduction of copper and oxidation of aluminum.

When the formation is continuously performed, copper is gradually deposited on the formation cathode plate 12, and as time elapses, the copper grows and becomes thicker, resulting in peeling. Before switching, the changeover switch 14 is switched to the side B in the figure to switch the polarity of the direct-current power supply 11 for formation, so that the aluminum foil 13 is used as a negative electrode and the formation cathode plate 12 is used as a positive electrode. Is dissolved in a chemical solution. The time for reversing the polarity may be extremely short, and the failure of the aluminum foil 13 caused by the polarity reversal hardly occurs. However, in the present invention, in order to minimize the failure of the aluminum foil 13, a seam of the original foil is used. At an interval of about 8 hours according to the timing of passing through the formation tank 4.
Performed for 0 seconds.

The time for maintaining the reverse polarity state is as follows.
Although it depends on the time of continuous chemical formation, copper dissolves in about 10 seconds, so it is better if it is longer than that, and after elapse of 20 seconds, which is the time maintained in the opposite polarity state,
The changeover switch 14 is returned to the A side in the figure again so that normal formation is continuously performed.

The copper dissolved in the chemical conversion solution by the polarity reversal is formed separately from the chemical conversion apparatus, and is configured so that a pair of electrodes is disposed in the circulating chemical conversion solution, not shown. A direct current is applied between the electrodes of the copper dissolving portion to deposit and remove the negative electrode plate on the negative electrode plate. Further, the aluminum foil 13 that has been formed in this manner is subjected to a post-treatment step in the post-treatment tank 6. And a drying step by a drying furnace 7 to complete an alloy-based cathode foil for an aluminum electrolytic capacitor.

Before the copper deposited on the formation cathode plate 12 becomes thicker with time and peels off, the formation cathode plate 1
2. By removing copper from above, the copper pieces do not float in the chemical conversion solution and do not adhere to the aluminum foil 13, so that an electrode foil of excellent quality can be stably obtained. is there.

[0034]

As described above, the method and apparatus for manufacturing an electrode foil for an aluminum electrolytic capacitor according to the present invention switch the polarity of a DC power supply for applying a DC current to an aluminum foil and a formation cathode plate at an oxide film forming portion. A polarity switching unit is provided. By operating the polarity switching unit, the copper dissolving step of applying a voltage having a polarity opposite to the polarity of the voltage applied to the aluminum foil during the formation of the oxide film forming step to the aluminum foil for a predetermined time is performed by the above oxidation By providing at predetermined intervals in the film forming process, copper deposited on the formation cathode plate during anodic oxidation in the oxide film formation process is dissolved by applying a voltage of the opposite polarity to the formation cathode plate to grow copper. To prevent copper from floating in the chemical conversion solution, and to produce high quality and highly reliable electrode foil for aluminum electrolytic capacitors without copper adhesion. It is what it is.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the configuration of an apparatus for manufacturing an electrode foil for an aluminum electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a configuration of a conventional apparatus for manufacturing an electrode foil for an aluminum electrolytic capacitor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unwinding roll 2 Pretreatment tank 3 Etching tank 4 Chemical tank 5 Copper removal tank 6 Postprocessing tank 7 Drying furnace 8 Winding roll 9 Etching cathode plate 10 DC power supply for etching 11 DC power supply for formation 12 Cathode plate 13 Aluminum foil 14 Changeover switch

Claims (6)

[Claims] 1. An etching step for increasing the surface area of an aluminum foil containing at least a trace amount of impurities, an oxide film forming step of forming an oxide film on the surface of the etched aluminum foil by anodic oxidation, and depositing on the surface of the aluminum foil. And a copper dissolving step of applying a voltage having a polarity opposite to the polarity of the voltage applied to the aluminum foil during the anodic oxidation of the oxide film forming step to the aluminum foil for a predetermined time. A method for manufacturing an electrode foil for an aluminum electrolytic capacitor, wherein the electrode foil is provided at predetermined intervals in an oxide film forming step. 2. The method for producing an electrode foil for an aluminum electrolytic capacitor according to claim 1, wherein the aluminum foil is an alloy-based cathode foil. 3. The method for producing an electrode foil for an aluminum electrolytic capacitor according to claim 1, wherein the impurity is copper. 4. An aluminum foil is supplied in the form of a roll in which a plurality of rolls each having a predetermined length are continuously spliced, and when a spliced portion of the rolls passes through an oxide film forming step. 2. The method according to claim 1, wherein a copper dissolving step is performed.
2. The method for producing an electrode foil for an aluminum electrolytic capacitor according to item 1. 5. An unwinding section for supplying a rolled aluminum foil, an etching tank for immersing the aluminum foil supplied from the unwinding section in an etching solution, and immersing in an etching solution in the etching tank. A DC current is applied from a DC power source for etching in which the etched aluminum foil is used as a positive electrode, and an etching cathode plate arranged opposite to both surfaces of the aluminum foil in the etching solution is connected to the negative electrode to chemically treat the surface of the aluminum foil. An etching section for electrically and electrically etching, and a chemical conversion tank for immersing the etched aluminum foil in a chemical conversion liquid, and using the aluminum foil immersed in the chemical conversion liquid in the chemical conversion tank as a positive electrode, DC current was applied from a DC power supply for formation in which a formation cathode plate arranged on both sides of the aluminum foil was connected to the anode. An oxide film forming part for forming an oxide film between the aluminum foil and the copper deposited on the aluminum foil by applying a heat treatment, and a DC power supply for chemical formation for applying a DC current to the aluminum foil and the cathode plate at the oxide film forming part A polarity switching unit for switching the polarity of the aluminum foil having an oxide film formed in the oxide film forming unit has a copper removal tank for immersing the aluminum foil in an acidic solution, and deposited on the surface of the aluminum foil in the copper removal tank. An apparatus for manufacturing an electrode foil for an aluminum electrolytic capacitor, comprising a copper removal part for dissolving and removing copper and a winding part for winding the aluminum foil passing through the copper removal part into a roll. 6. The apparatus for producing an electrode foil for an aluminum electrolytic capacitor according to claim 5, wherein a pair of electrodes connected to a DC power supply are disposed in a chemical solution circulating in the chemical formation tank.