JP2002053992A - Method for manufacturing metallic foil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the consumption of an electrode coating in a method of manufacturing metallic foil by electrolysis from a nitric acid acidic solution using an anode having the coating containing a platinum group metal or metal oxide. SOLUTION: In the method of manufacturing metallic foil by electrolysis from a nitric acid acidic solution, by adding a lead carbonate into the nitric acid acidic solution of electrolyte while using the anode having the coating of a platinum group metal or platinum group metal oxide formed, electrolysis is performed in the state of maintaining the lead concentration in the electrolyte at >=10 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for continuously producing a metal foil such as a copper foil mainly used for a printed wiring board or the like.

[0002]

2. Description of the Related Art There are various methods for producing a metal foil depending on its material or use. A method of producing a metal foil by rolling and a method of electrodepositing an aqueous solution of a metal compound on a cathode by electrolysis using an electrolytic solution as an electrolytic solution. A typical example is a method based on electrolysis, which is manufactured by using an electrolysis method. Most copper foils used for printed circuit boards for electronic circuits are manufactured by electrolysis. This is because, in the case of electrolytic copper foil, even if inexpensive scrap copper or the like is used as a raw material, components that do not precipitate at the deposition potential of copper from the electrolytic solution do not migrate into the copper foil, so impurities Can be obtained.

[0003] Further, the electrolytic copper foil has a feature that a foil having a uniform thickness can be easily obtained over a wide area, and the structure of metal deposited by electrolysis is suitable for the purpose of forming an electronic circuit. And has a feature that etching with a large aspect ratio can be easily performed.

FIG. 1 illustrates an example of an apparatus for producing copper foil by electrolysis. As shown in the cross-sectional view of FIG. 1, a large cathode drum 4 whose lower part is immersed in an electrolytic bath 3 in an electrolytic cell 2 is used as a cathode, and an insoluble anode 5 is used as a counter electrode to supply a current to supply an electrolytic solution of the anode. This is a method in which metal copper 7 deposited while continuously depositing metal on the surface of the drum from the slit 6 while supplying an electrolytic solution is continuously peeled off from the surface of the cathode drum 4. The average thickness can be easily controlled by changing the supplied current value or the drum rotation speed, so that a thin foil can be easily formed.

[0005] The thickness of the electrolytic copper foil is usually 10 to several tens of µm, and a lead electrode or a lead alloy electrode is used as the anode. In addition, the quality of the obtained copper foil was adversely affected. Therefore, an insoluble metal electrode in which a coating of an electrode catalyst material containing a platinum group metal or a platinum group metal oxide is coated on a substrate of a thin film-forming metal such as titanium or a titanium alloy is being used as an anode. . However, when an insoluble metal electrode coated with a platinum group metal or metal oxide is used as the anode, the life of the anode may be significantly longer than when a lead electrode is used, but it should be used forever. However, there has been a demand for a method for producing a metal foil that reduces the consumption of an insoluble metal electrode and enables long-term use.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a metal foil such as an electrolytic copper foil by electrolysis using an insoluble metal electrode coated with a platinum group metal or a platinum group metal oxide for a long time. The purpose of the present invention is to stably perform electrolytic production of a metal foil over a long period of time.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a metal foil from a sulfuric acid acid solution, wherein an anode coated with a platinum group metal or a platinum group metal oxide is used, and The problem can be solved by a production method by electrolysis of a metal foil in which electrolysis is performed in a state where the lead concentration in an electrolytic solution is maintained at 10 ppm or more by adding a carbonate of lead to an acidic solution. Further, the present invention is a method for producing the metal foil by electrolysis, wherein the metal foil is a copper foil.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the production of a metal foil by electrolysis, the consumption of the electrode active coating formed on the insoluble metal electrode is added to the electrolytic solution in order to improve the electrodeposition of the metal foil on the cathode drum. It has been clarified that the increase is caused by the presence of various organic additives or fluorine ions. The present applicant has disclosed a method for electrolytically producing a metal foil while forming a stable lead dioxide coating on an electrode active coating by including a lead component in an electrolytic solution.
No. 052.

In the production of metal foil, additives such as gelatin, glue, thiourea and cellulose are used at a concentration of several ppm to several tens ppm in order to improve foil characteristics. All of these are known to promote the consumption of the coating of the electrode active material containing the self-metal group metal oxide serving as the anode, thereby shortening the life of the anode. Lead dioxide that precipitates on the anode during electrolysis has the effect of mitigating the adverse effects of such additives, and for that purpose, it is necessary that the lead concentration in the electrolytic solution be at least a certain value. The present inventors have studied the lead concentration and found that at 8 ppm, no effect of extending the anode life was observed, and it was found that at least 10 ppm or more was required. The concentration of the lead component in the electrolytic solution can be adjusted by dissolving the lead introduced from the raw material, or the metal or various lead compounds in the electrolytic solution,
There was a problem that the lead concentration in the electrolyte was limited by the solubility product with the sulfate in the electrolyte. When the concentration of the lead component in the sulfuric acid acidic electrolytic bath was examined, several pp
It is difficult to increase the concentration to about m or more.
The limit was about 8 ppm.

[0010] The inventors of the present invention have conducted intensive studies on a method capable of increasing the lead concentration in an electrolytic solution and stably maintaining the lead component concentration over a long period of time. When lead powder, lead dioxide, lead sulfate, etc. were dissolved in an acidic solution, even if the lead concentration temporarily increased, the lead concentration could not be stably maintained for a long period of time, When using lead carbonate,
It has been found that the concentration of the lead component can be stably maintained at 10 ppm or more. Lead carbonates include lead carbonate (PbCO ₃ ) and basic lead carbonate (2Pb
CO ₃ .Pb (OH) ₂ ) or the like can be used. These lead carbonates dissolve in the sulfuric acid acidic electrolyte while generating carbon dioxide. The reason for this is not clear, but the process of dissolving the lead carbonate in the sulfuric acid bath is an electrolytic process. It is presumed that they play an effect in increasing the concentration of lead in the liquid.

In the present invention, the lead carbonate added to the electrolytic solution can be dissolved in the copper raw material dissolving tank. The amount of lead carbonate may be added in excess to the amount dissolved, and if added in excess, the excess will become lead sulfate etc. and form a precipitate. Since they are separated, they do not adversely affect the metal foil deposition process.

[0012]

The present invention will be described below with reference to examples. Example 1 100 g / l diluted sulfuric acid was heated to 60 ° C., and an excess amount of lead carbonate was added. Once a day, the solution was collected and filtered through a membrane filter, and the lead concentration was analyzed and quantified using an induction plasma emission spectrometer (ICP). The results are shown in Table 1 together with Comparative Examples.

Example 2 Copper concentration 80 g / l, sulfuric acid concentration 95 g / l, lead concentration 4 pp
m, in a copper dissolving tank for a copper foil electrolyte having a gelatin concentration of 10 ppm, lead carbonate was converted to lead per liter of electrolyte in a copper solution of 0.1 ppm.
2 g were charged. The electrolytic cell is a composite oxidation containing 70:30 (molar ratio) of iridium and tantalum on an electrode substrate made of an arc-shaped titanium plate with a distance of 10 mm between electrodes with respect to a titanium drum type cathode having a diameter of 2 m. Anodes formed by pyrolysis of an electrode catalyst coating made of
Were arranged as shown in FIG. When the lead concentration in the electrolytic solution increased from 4 ppm to reach 12 ppm, electrolysis was started at a bath temperature of 50 ° C. at an anode current density of 40 A / dm ² . The electrodeposited copper was wound up in a foil form, and the concentration of lead in the electrolytic solution was analyzed in the same manner as in Example 1. Also, the anode could be operated without replacement for 10 months.

Comparative Example 1 Analysis was performed in the same manner as in Example 1 except that lead dioxide was used instead of lead carbonate in Example 1. Table 1 shows the results.

Comparative Example 2 Analysis was performed in the same manner as in Example 1 except that lead sulfate was used in place of lead carbonate in Example 1. Table 1 shows the results.

Comparative Example 3 Analysis was performed in the same manner as in Example 1 except that lead metal powder having an average particle size of 45 μm was used instead of the lead carbonate of Example 1. Table 1 shows the results.

Comparative Example 4 0.2 g of lead metal powder having an average particle diameter of 45 μm was charged per liter of an electrolytic solution, and the lead concentration increased from 4 ppm to 8 μm.
When the concentration reached ppm, electrolysis was started in the same manner as in Example 2, the deposited copper was wound up in a foil shape, and the concentration of lead in the electrolytic solution was analyzed in the same manner as in Example 1. It is shown in Table 1. After the operation for 6 months, the thickness distribution was generated in the width direction of the copper foil, and the copper foil could not be wound. In addition, when the anode was removed from the electrolytic cell and examined, it was confirmed that the electrode catalyst coating was partially consumed, and that the cause was that the thickness of the copper foil was uneven due to the consumption of the electrode catalyst coating.

[0018]

Table 1 Changes in lead concentration in dilute sulfuric acid Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 hours Lead carbonate Lead carbonate Lead dioxide Lead sulfate Metal lead powder Metal lead powder 10.4 1.9 0.9 1.2 7.8 2 days 8.8 10.7 9.3 5.0 8.4 9.3 3 days 12.2 9.2 5.6 9.3 4 days 11. 9 7.1 5.3 10.46 6 days 10.4 6.6 8.0 6.8 7.6 7 days 11.8 6.6 8.0 6.8 8 days 11.1 11.56 8.4 8.4 7.0 7.9 9 days 11.3 6.9 7.1 5.9 13 days 11.6 7.6 15 days 11.3 7.5 22 days 11.2 8.4 27 Days 11.7 7.6 29 days 12.1 7.6 34 days 11.8 7.2 41 days 12.2 8.1 43 days 12.1 8.6

[0019]

According to the present invention, by adding lead carbonate, the concentration of lead in the electrolytic solution is maintained at a high level of 10 ppm or more, whereby stable lead dioxide can be quickly deposited on the insoluble metal electrode. This lead dioxide served as an electrode catalyst for oxygen generation, and could significantly extend the life of the anode itself.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a metal foil manufacturing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Copper foil manufacturing apparatus, 2 ... Electrolysis tank, 3 ... Electrolysis bath, 4 ... Cathode drum, 5 ... Anode, 6 ... Electrolyte supply slit, 7 ... Metal copper, 8 ... Copper foil

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tamio Ishikawa No.8, No.2, No.2, Douliu-shi, Yunlin County, Taiwan Taichung Furukawa Copper Foil Co., Ltd. (72) Inventor Akihiro Kato Fujisawa, Kanagawa Prefecture Endo 2023-15 Permelec Electrode Co., Ltd. (72) Inventor Shuji Nakamatsu Endo 2023-15 Permelec Electrode Co., Ltd., Fujisawa-shi, Kanagawa

Claims (1)

[Claims] In a method for producing a metal foil from a sulfuric acid solution, an anode coated with a platinum group metal or a platinum group metal oxide is used, and lead carbonate is added to the sulfuric acid solution of the electrolytic solution. The lead concentration in the electrolyte to 10p
a method for producing a metal foil by electrolysis, wherein the electrolysis is performed while the pressure is maintained at pm or more.