WO2004079053A1

WO2004079053A1 - Process for producing electrolytic copper foil

Info

Publication number: WO2004079053A1
Application number: PCT/JP2004/002869
Authority: WO
Inventors: Hisao Sakai; Shinichi Obata; Makoto Dobashi
Original assignee: Mitsui Mining & Smelting Co., Ltd.
Priority date: 2003-03-07
Filing date: 2004-03-05
Publication date: 2004-09-16
Also published as: JP2004269950A

Abstract

A process for producing an electrolytic copper foil using sampled copper sulfate solution being discharged from a copper refining process in order to supply a low-cost electrolytic copper foil for printed wiring board to the market. The process for producing an electrolytic copper foil by electrolyzing copper sulfate solution is characterized in that copper sulfate solution sampled from a refining electrolytic cell for obtaining electric copper is employed after being subjected to activated carbon treatment. The process for producing an electrolytic copper foil by electrolyzing copper sulfate solution is characterized in that copper sulfate solution is sampled from a refining electrolytic cell for obtaining electric copper and subjected to activated carbon treatment and then added with an additive for improving the physical properties of the copper foil.

Description

Description Name of Invention

Manufacturing method of electrolytic copper foil

The present invention relates to a method for producing an electrolytic copper foil.

Background technology

First, the history of the development of a method for producing an electrolytic copper foil is described. The production of electrolytic copper foil was started in the early 1930s by Anaconda (USA), the world's largest copper producer at the time. The origin of the production of this electrolytic copper foil is as follows.In copper refining electrolysis, copper components eluted into sulfuric acid from blister copper are deposited on the seed copper of the cathode by using blister copper containing impurities in the anode and seed copper in the cathode to form copper electrolytic copper. It is collected as. At this time, the amount of copper eluted from the blister copper is greater than the amount of copper precipitated as electrolytic copper, so the copper concentration in the electrolyte gradually increases. Therefore, in order to maintain the copper concentration in the electrolyte within a certain range, and to extract copper of stable quality as an industrial product, it is necessary to constantly withdraw the electrolyte (hereinafter referred to as the extracted electrolyte). The solution is referred to as “sampled copper sulfate solution”.)

This extracted copper sulfate solution is a so-called copper sulfate solution, and production of electrolytic copper foil was attempted in order to effectively use the copper sulfate solution. At that time, the equipment for producing electrolytic copper foil already had a drawn copper sulfate solution, which is a copper sulfate solution, flowing between a rotating cathode in the form of a drum and a lead-based anode placed opposite to the rotating cathode. However, copper was deposited on the drum surface of the rotating cathode using an electrolytic reaction, and the deposited copper became a foil state, which was continuously peeled off from the rotating cathode and wound up. The electrodeposited copper foil obtained in this way was referred to as an electoru-kappa sheet at that time, and was mainly used for building materials and decorative purposes.

Then, in the 1950's, transistors became practical and electronic Printed wiring boards have come to be used for wiring products. When the etching method is used to form the circuit of the printed wiring board, it is necessary to use a copper foil which is made of copper in the same manner as general copper wire and which can be designed with the same circuit resistance. Has proven to be very advantageous. At this time, the rolled copper foil and the electrolytic copper foil were present in the copper foil. Rolled copper foil has a high manufacturing cost due to its manufacturing method, but its copper purity can be adjusted and it satisfies the electrical resistance specifications required for electronic products. On the other hand, the electrolytic copper foil at that time was cheaper in production cost than the rolled copper foil and could be provided at a lower price, but the extracted copper sulfate solution contained many impurities such as zinc, calcium, nickel, and arsenic. The electrical resistance increased compared to copper foil, and the electrical resistance specifications required for electoronics products could not be satisfied.

Therefore, if high-purity electrolytic copper foil can be produced, rolled copper foil is not a problem, and it is clear that the use of electrolytic copper foil in the electronics field will rapidly expand. Against this background, Circuit Oil Company (USA) was established to supply electrolytic copper foil for printed wiring boards.

In order to produce high-purity electrolytic copper foil that can be used in the electronics field, Circuit Oil has given up using conventional copper sulfate solution instead of dissolving copper wire with sulfuric acid and adding copper sulfate solution with less impurities. It was decided to use. This concept is based on the idea that Clevit (later Gould), a manufacturer of electrolytic copper foils for electronics that was established to date, is now an electrolytic copper foil manufacturer in Japan, including the Company, and other Taiwanese companies. It is used by all electrolytic copper foil manufacturers in Korea, China and other countries. The contents related to the technical background described above and the production of conventional copper foil for printed wiring boards are disclosed in various patent documents and technical documents shown below. For example, U.S. Pat. No. 1,952,762, U.S. Pat. No. 1,978,037, U.S. Pat. No. 2,035,517, U.S. Pat. 044, 415, U.S. Patent No. 2,051,923, BOUNDARY "Electrodeposited copper foil encountered a printed circuit was fortunate (by Kazuo Mase)" Month issue). However, in the field of electronics in recent years, global price competition has become intense, and the production of electrolytic copper foil in emerging industrial countries has become active. As a result, price reductions have progressed sharply, creating a situation that has put pressure on the management of domestic electrolytic copper foil manufacturers.

On the other hand, the demand for downsizing of electronic and electrical equipment is boundless, and there is a strong need for multi-layer printed wiring boards that are the basic components, higher density of circuits, and higher density of mounted components. As a result, there is a growing demand for improving the quality of electrolytic copper foil.

Against this background, copper foil manufacturers in Japan have been able to supply products equivalent to those of conventional electrolytic copper foil to the market at even lower cost, and have an international competitiveness to compete with products from overseas countries. Need to be raised.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a comparison of the metal component content in the liquid before and after activated carbon filtration. FIG. 2 shows a comparison of the content of the impurity metal component in the electrolytic copper foil produced using each copper sulfate solution before and after the activated carbon filtration. Fig. 3 shows the roughened surface shape of the electrolytic copper foil produced using each copper sulfate solution before and after activated carbon filtration.

Overview of the invention

The inventors of the present invention, as a result of diligent research, returned to the origin of electrolytic copper foil production and found that even with the above-mentioned extracted copper sulfate solution, the same electronics as high-purity electrolytic copper foil supplied to the conventional market were used. They have come up with a method that can produce electrolytic copper foil with a purity that can be used in applications. The idea of producing electrolytic copper foil with a purity that can be used for electronics using the extracted copper sulfate solution has been neglected by those skilled in the art for more than 50 years.

The basic technical idea of the present invention is as described in the claim: `` In a method for producing an electrolytic copper foil by electrolyzing a copper sulfate solution, the copper sulfate solution is withdrawn from a refining electrolytic cell for obtaining electrolytic copper. The extracted copper sulfate solution is treated with activated carbon. A method for producing an electrolytic copper foil, comprising: It is to adopt. Here, "the extracted copper sulfate solution extracted from the refining electrolytic cell for obtaining the electrolytic copper" contains various impurities in the extracted copper sulfate solution. Generally, the most common impurities are nickel, arsenic, iron, calcium, aluminum, zinc, magnesium and the like, and also include glue and thiourea which are intentionally added.

The greatest feature of the present invention lies in that this solution is treated with activated carbon. Certainly, activated carbon treatment of a plating solution or the like is generally used for cleaning a solution, and it is apparent that the same cleaning effect can be obtained by filtering the extracted copper sulfate solution with activated carbon. However, the cleaning effect referred to here is to remove so-called organic substances such as glue in a solution and decomposition residues of the organic substances, and to adsorb and remove a part of metal components that are ionized. It has been considered promising. In the activated carbon treatment according to the present invention, it is desirable to employ treatment conditions that enable the activated carbon to come into contact with the extracted copper sulfate solution for 5 hours or more. For example, `` Add activated carbon to the extracted copper sulfate solution and stir it for at least 5 hours to make contact '', `` Disperse the activated carbon in the precoat attached to the leaf of the ultrafiltration machine and make it very loose and the activated carbon and extracted copper sulfate Contact with a solution. "

To confirm this, the present inventors compared the metal component content of the extracted copper sulfate solution (manufactured by Hibi Kyodo Co., Ltd.) before and after activated carbon filtration. Figure 1 shows the results. As can be seen from FIG. 1, the content of each metal component in the liquid hardly changed before and after activated carbon filtration. However, using the extracted copper sulfate solution before and after the activated carbon filtration described above, a titanium plate was placed on the cathode and an insoluble DSE electrode was placed on the anode so that the distance between the electrodes was 10 mm, and the solution temperature was 48 ° C and the current density was An electrolytic copper foil of 35 m was produced at 35 AZ dm ² . Then, the amounts of impurities in the two electrolytic copper foils obtained here were analyzed, and the results are shown in FIG. As can be seen from Fig. 2, despite the fact that the content of each metal component in the solution does not change, the amount of impurity elements contained in the copper foil manufactured using the extracted copper sulfate solution filtered with activated carbon was low. It is extremely low.

Moreover, as is clear from Fig. 3, the rough surface of the copper foil produced using the extracted copper sulfate solution treated with activated carbon (Fig. 3 (A)) and the extracted copper sulfate solution not treated with activated carbon were used. Comparing with the rough surface of copper foil manufactured using the liquid (Fig. 3 (B)), the latter rough surface of the copper foil has many abnormal deposition spots and is not uniform. Therefore, by using the extracted copper sulfate solution that has been treated with activated carbon, the stability of copper precipitation can be maintained.

The following can be understood from these facts. The activated carbon treatment used in the present invention removes only organic additives such as glue and thiourea in the solution, and does not remove contained metal ions. I think that when the organic additive is removed from the sampled copper sulfate solution, copper electrolysis using the solution suppresses the precipitation of impurity metal components other than copper, and satisfies the copper purity required for electrolytic copper foil for printed wiring boards. It is thought that the product which was obtained is obtained.

Further, the electrolytic copper foil may be produced by adding an additive such as glue to a copper sulfate solution for controlling physical properties. Therefore, the inventors of the present invention have filtered the extracted copper sulfate solution extracted from the refining electrolytic cell for obtaining the electrolytic copper with activated carbon, and then added an additive for improving the physical properties of the copper foil. As described above, they have found that it is possible to produce an electrolytic copper foil without containing the impurity component contained in the extracted copper sulfate solution.

The additives mentioned here mainly refer to organic additives such as glue, gelatin, and surfactants. In the case of electrolytic copper foil, the purity of its components is a problem, and it is hardly conceivable to use metal additives except when trying to produce copper alloy foil.

Next, the current density used during electrolysis will be described. In the production of electrolytic copper foil, a copper component is deposited on the surface of the cathode in a manner to make it smooth, and this is stripped off. Therefore, it is clear that the current density must be within the range that allows smooth copper plating. That is, the relationship between the copper concentration and the current density largely determines the condition of copper smoothness. If the copper concentration is low, the current density will normally be low unless the current density is set low. Conventionally, the copper concentration in the copper sulfate solution used for the production of copper foil for printed wiring boards has been increased to 80 g Z1 as a solution with a high copper concentration and high current density electrolysis to improve production efficiency. Have been.

However, the copper concentration of the extracted copper sulfate solution extracted from the electrolytic cell for obtaining electrolytic copper The density is usually 55 g / 1 or less, and it is not possible to perform electrolysis at a high current density exceeding 5 OAZdm ² used in the production of the current copper foil for printed wiring boards. Therefore, by setting the current density lower, it is possible to produce electrolytic copper foil that satisfies the purity of copper foil for printed wiring boards. Here, since there is no particular problem regarding the low current density, it is not necessary to particularly consider the lower limit of the current density. However, considering the industrial base, it is advantageous to secure high productivity at the highest possible current density, and operating conditions near the upper limit current density will be determined.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an example in which an electrolytic copper foil is manufactured using the method for manufacturing an electrolytic copper foil according to the present invention will be described.

(First embodiment)

In this example, using the extracted copper sulfate solution with activated carbon treatment shown in Fig. 1 above, a titanium electrolytic drum for the cathode, an insoluble DSE electrode for the anode, and an interelectrode distance of 10 mm were arranged. Then, an electrolytic copper foil of 35 m was manufactured at a solution temperature of 52 ° C. and a current density of 37.5 AZdm ² . The properties of the resulting electrolytic copper foil are shown below. The activated carbon filtration treatment at this time was performed by adding activated carbon to the extracted copper sulfate solution at a concentration of 5 g / 1, stirring for 12 hours, and filtering. The physical properties of the copper foil shown below are basically measured according to IPC-TM-650. However, as for the roughness, "center line average roughness (Ra)" and "10 point average roughness (Rz)" described in JISB0601 are used. Unit weight: 279 g / m ²

Surface roughness: glossy surface R a = 0.25 m, R z = 1.82 im

Rough surface Ra = 0.95 urn, R z = 6.10 0 ^ m

Tensile strength: Normal 41.6 kg f / mm ² After heat 24.7 kg f / mm ²

Elongation: Normal 1 7.9%

After heat 22.8%

Copper purity: 99. 99% or more

Electrical resistance: shows the physical properties of HTE class 0. 160 Ω- g / m ² or more of the properties I PC standard, ordinary Japanese Patent wire ratio Comparative Examples 1 described below was obtained by dissolving in sulfuric acid There is no difference between the physical properties of the electrolytic copper foil (HTE) obtained using the copper sulfate solution. Therefore, it is clear that the properties as an electrolytic copper foil for a printed wiring board can be sufficiently satisfied.

(Second embodiment)

In this example, using the extracted copper sulfate solution with activated carbon treatment used in the first example, glue was added to the extracted copper sulfate solution after the activated carbon treatment so as to have a concentration of 3 ppm. In the same manner as described in Example 1, a 35 xm electrolytic copper foil was produced. The properties of the resulting electrolytic copper foil are shown below. Unit weight: 275 gXm ²

Surface roughness: glossy surface R a = 0.25 urn, R z = 1.47 / 2 m

Rough surface R a = = 0.86 urn, R z

Tensile strength: Stand 39.5 kgf / mm ²

After heat 38.2 kgf Z mm ²

Elongation rate: always 13.0%

After 15.5%

Copper purity: 99 99% or more

Electrical resistance: 0. 1 61 Ω- - g / m 2 or more of the properties can be prepared by dissolving the conventional Japanese Patent wire of Comparative Example 2 described below with sulfuric acid ', a copper sulfate solution obtained by adding glue What is the difference between the physical properties of the electrolytic copper foil obtained by using It is not. Therefore, it is clear that the properties as an electrolytic copper foil for a printed wiring board are sufficiently satisfied.

(First comparative example)

In this comparative example, a special copper wire was dissolved with sulfuric acid to produce a copper sulfate with a copper concentration of 80 g / sulfuric acid concentration of 150 gZ1 as in the conventional method of manufacturing electrolytic copper foil for printed wiring boards. Using the solution, an electrolytic copper foil of 35 im was produced under the same electrolysis conditions as those used in the first example. The properties of the resulting electrolytic copper foil are shown below. Unit weight: 284 g / m ²

Surface roughness: Glossy surface Ra = 0.26 nm, Rz = 1.83 urn

Rough surface R a = 1.18 urn, R z = 7.18

Tensile strength: Normal 38.8 kf / mm ²

After heat 29.5 kg f / mm ²

Growth rate: Normal 19.7%

After heat 21.3%

Copper purity: 99. 99% or more

: 0.160 Ω-g, / m-Each of the above physical properties indicates the physical properties of the HTE foil of the IPC standard obtained by the usual method for producing an electrolytic copper foil. These are to be compared with the first embodiment described above. As can be seen from this, the physical properties of the electrolytic copper foil obtained in the first example are not inferior to those of the copper foil of the first comparative example.

(Second comparative example)

In this comparative example, a special copper wire was dissolved with sulfuric acid, and the copper concentration was 80 g / the sulfuric acid concentration was 150 g / 1, as in the conventional method of manufacturing electrolytic copper foil for printed wiring boards. A copper solution was added, glue was added thereto to a concentration of 3 ppm, and a 35 m electrolytic copper foil was manufactured using this solution under the same electrolytic conditions as those used in the first example. The properties of the resulting electrolytic copper foil are shown below.

282 g / m ²

Surface roughness Glossy surface Ra = 0.26 / im, R z 72 m

Rough surface Ra = 0.888 urn, R z 37 u

Tensile strength Normal 32.9 kg f / mm ²

After heat 33.8 kg f / mm ²

Growth rate Normal 6.0%

After heat 15.2%

Copper purity 99. 99% or more

0. 1 62 Ω - g / m 2 or more of the properties shows I PC standard Class 3 foil properties of obtained by the process of the conventional electrolytic copper foil. These are comparable to the second embodiment described above. As can be seen from the above, the physical properties of the electrolytic copper foil obtained in the second example are not inferior to those of the copper foil of the second comparative example.

(Third Comparative Example) In this example, an electrolytic copper foil of 35 m was manufactured under the same electrolytic conditions as in the first example using the extracted copper sulfate solution without the activated carbon treatment shown in FIG. . The properties of the resulting electrolytic copper foil are shown below. At this time, it is clarified that no activated carbon filtration was performed. Unit weight: 279 g / m ²

Surface roughness: glossy surface R a = ■■ 0.25 um, R z = = 1.82 zm

Rough surface R a =: 0.98 Aim, R z = = 6.88 ίΐνα Tensile strength: normal 42.3 kgf / mm ²

After heat 23.1 kgf / mm ²

Elongation: Normal 1 7.9%

After heat 22.8% Copper purity: 99.9%

Electrical resistance: Comparing each physical property of 0.165 Ω-g / m ² or more with the physical properties of the above embodiment, the copper purity is poor, and as a result, the electrical resistance is lower than that of the copper foil for printed wiring boards. The required level has not been reached. Therefore, although it can be used for decoration, the physical properties as electrolytic copper foil for printed wiring boards are not satisfied.

Industrial applicability

According to the method for producing an electrolytic copper foil according to the present invention, the technique that a person skilled in the art has given up for many years is improved from a new point of view, so that it can be said that the origin of the copper foil is `` extracted from the electrolytic cell for obtaining electrolytic copper '' It is possible to manufacture high-quality electrolytic copper foil for printed wiring boards using the “sampled copper sulfate solution” as a raw material. If such a manufacturing method can be established, the process of dissolving the conductive wire with sulfuric acid is not required, and the production line can be significantly shortened. In addition, by using the extracted copper sulfate solution generated from the electrolytic refining of copper, untitled use of resources can be suppressed, and extremely inexpensive copper foil can be supplied.

Claims

The scope of the claims

1. A method for producing an electrolytic copper foil by electrolyzing a copper sulfate solution, wherein the copper sulfate solution is obtained by treating an extracted copper sulfate solution withdrawn from a refining electrolytic cell for obtaining electrolytic copper with an activated carbon treatment. Method for producing an electrolytic copper foil.

2. In the method of producing an electrolytic copper foil by electrolyzing a copper sulfate solution, the copper sulfate solution is subjected to activated carbon treatment of a copper sulfate solution extracted from a refining electrolytic cell for obtaining electrolytic copper, and thereafter the physical properties of the copper foil are improved. A method for producing an electrolytic copper foil, characterized by adding an additive for performing the method.