JPS62240785A - Production of high purity copper - Google Patents

Abstract

PURPOSE:To economically produce high purity Cu in large quantities when Cu is electrolytically refined, by bringing part of an electrolytic soln. contg. Cu sulfate acidified with sulfuric acid into contact with an Ag adsorbing substance so as to remove impurities. CONSTITUTION:An anode of Cu as starting material and a cathode on which Cu is electrodeposited are placed opposite to each other in an aqueous Cu sulfate soln. acidified with sulfuric acid as an electrolytic soln. One or more kinds of compounds such as Cu or Pd sulfide, selenide and telluride are used as an Ag adsorbing substance. This Ag adsorbing substance is brought into contact with part of the electrolytic soln. to treat the soln. and electrolysis is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to high-purity Cu, particularly purity 99.99-99.99.
The present invention relates to a method for manufacturing high-purity steel that has excellent conductivity properties of 9% or more, softness, and low-temperature softening properties.

(Prior art) Electrical Cu has a purity of 99.95% or more, usually 99.95-9
It is used as tough pitch Cu containing 9.99% and 100 to 500 ppm of 02 and OFC containing 5 to 20 ppm of 02, and is used in bonding wires for semiconductors, sputter targets, soft rolled printed wiring, thin electrical wires for audio, etc. There is. All of these are Pb, Sb, Ni1Bi, As, and F in crude Cu by electrolysis.
Impurities such as e and Zn are separated with high refining efficiency.
In addition to the above-mentioned impurities, which are usually truer than Cu or more base, S,
Contains trace amounts of 0, C, etc., and these impurities are high purity C.
It is harmful to the properties of u.

Therefore, when higher purity Cu is required, special methods such as zone melting, float melting, or distillation are used.

(Problems to be solved by the invention) The above-mentioned special method for producing 1 q of high-purity Cu is limited to small-scale production and is extremely expensive.
Unable to meet the above-mentioned large demand that focused on the characteristics of
There is a strong demand for the development of a continuous industrial manufacturing method, that is, a manufacturing method that satisfies the following requirements.

(1> High purity, that is, pure Cu with a purity of 99.99 to 99.999% or higher can be continuously mass-produced.

(2) Impurities that are particularly harmful to the properties of high-purity Cu, such as S
, 0, CAg can be removed efficiently.

(3) Efficiently remove impurities that cannot be removed even by using a normal industrial electrolytic method and repeating this process multiple times. That is, it is possible to obtain a degree of refinement that cannot be achieved simply by repeating conventional industrial methods.

(4) Has affinity with Cu, which is the most difficult to separate using conventional methods,
In addition, it is possible to efficiently separate and recover Ag, which is an element similar to the substance.

[Means for solving problems]

In view of this, as a result of various studies, the present invention has developed a method for producing high-purity Cu1, particularly high-purity copper with a purity of 99.99 to 99.999% or higher, which has excellent conductive properties, softness, and low-temperature softening properties.

One of the manufacturing methods of the present invention is to use an anode made of a Cu raw material and a C
The method is characterized in that cathodes for electrodepositing U are disposed opposite each other, and at least a portion of the circulating electrolyte is brought into contact with an AQ-adsorbing substance for electrolytic treatment.

Another manufacturing method of the present invention is to electrolytically process at least a part of the circulating electrolyte by contacting it with an AC7 adsorptive substance by disposing an anode made of a Cu raw material and a cathode for electrodepositing Cu. After that, the electrodeposited Cu is dissolved and subjected to an oxidation treatment, and then a reduction treatment or a re-dissolution in a vacuum after the reduction treatment.

That is, when electrolytically refining high-purity Cu by placing a Cu raw material at an anode and a cathode for electrodepositing Cu, at least a part of the electrolyte is brought into contact with an A (J adsorbent substance. Although a H2So+ solution in which 50% of H2SO+ is dissolved is preferable, an aqueous solution of sulfamic acid, borofluoric acid, acetic acid, nitric acid, ammonia, cyanide, organic amines, etc. may also be used.

The raw material CU is electrolytically treated and deposited on an insoluble metal such as Ti, Zr, SUS or a cathode of high purity Cu. It is advantageous to heat and circulate the electrolytic solution, and the electrolytic current is approximately in the range of 0.01 to 10 A/dm2, depending on the conditions, and a large number of anodes and cathodes are arranged alternately in the same tank. This allows for long-term production.

In addition to a heat exchanger, a filter, etc., the electrolytic solution is fluidized and circulated through a pump-driven circulation system through a contact treatment process with an Ag-adsorbing substance.

Among Ag adsorbents, sulfides, selenides, tellurides, sulfur, selenium, etc. of CU and Pb are particularly effective among specific chelate resins, specific activated carbons, specific inorganic gels, etc.
These can be used alone or together with a suitable support and packed in a column. The adsorption amount is determined empirically based on the raw material Cu and electrolytic conditions. The degree of purification can be further increased by repeatedly electrolytically treating the Cu electrodeposited on the cathode as an anode.

In the above electrolytic purification, the degree of purification can be further improved by partitioning the anode and cande with an electrolyte-permeable diaphragm, performing the adsorption treatment on the anode side, and then refluxing the electrolyte to the cathode side. As the diaphragm, unglazed ceramics, porous inorganic materials such as asbestos cloth, organic polymer cloths such as Saran cloth, etc. are used.

In addition, the CU obtained above is heated and melted above the melting point,
For deoxidation and reduction, molten Cu is brought into contact with the atmosphere or 02 gas in advance, and oxidized Cu is added to increase the 02 content in Cu to 20 to 11,000 pp.

Desirably, the amount is set to 50 ppm or more, and then the amount of H2, natural scum, CO, charcoal W, 7 elements, and 02 is set to 20 ppm or less, preferably 5 pI)m or less. This process is repeated as necessary, and more preferably, the residual gas is completely removed by remelting in vacuum or by treating the molten metal. Vacuum degree is 10'r
Orr or less is desirable.

(Function) Electrical Cu is J: sea urchin Ag defined in JISI+2121 is added to Cu. This is based on the fact that AQ does not reduce the electrical conductivity, but Ag is also a harmful component in high-purity Cu, for which demand has recently increased. By electrolytic refining and repeating this process, metal impurities other than Ag, such as Fe, Zn, 3n, Ni, P
b, 3b.

3i, AS, Cd, etc. can be removed to 190 m or less, but Ag is not removed at all. The present invention can efficiently remove 1 to zoppm of Ac2 remaining in electric Cu. The Ag content in electric Cu is in a state of solid solution in Cu, and is eluted as ACJ+ during electrolysis, and is 0.
．． At a slight NG level of 1ppm or less, most of the NG is deposited on the cathode, but in the present invention, by adsorbing and removing a trace amount of /'l+, Ag
This made it possible to eliminate

Among adsorbents, Cu and Pb sulfides, selenides, and tellurides, especially Cu sulfides and selenides, are effective, and on the particle surface Cu2 S+A g-A g
CuS+Cu +10Cu2 S+2Ac>-+A g
An exchange reaction such as "Z S Cu" occurs, and Ag can be immobilized.

The most effective implementation state of the present invention is to separate the anode and cathode with a diaphragm, and perform the above-mentioned adsorption treatment on the liquid on the anode side to remove a trace amount of Ac, which is then refluxed to the cathode side.
At the same time, impurities and colloidal particles eluted from the anode are also adsorbed and microfiltered, and the highly purified liquid is supplied to the cathode side, thereby reducing the time required for reflux treatment and maximizing adsorption and filtration efficiency.

By repeating the above electrolysis as necessary, metal impurities can be highly purified to 1 DI) lit or less. Also remaining l
The amount of nonmetallic components such as -+2, S, 0, and C reaches 10 ppm or more, depending on the electrolytic bath composition and electrolytic conditions. These can be completely removed by melting the Cu electrodeposited on the cathode, followed by an oxidation-reduction treatment, and further by adding a vacuum degassing step. Trace amounts of S, O, C, etc. are unavoidably mixed into the electrolyte as additive components such as cavin, glue, thiourea, etc., and have an extremely harmful effect on the properties of high-purity Cu, especially its softness and softening properties. This is completely removed by the above treatment.

〔Example〕

(1) An anode made of an industrial electric CU and an insoluble cathode made of Ti are placed opposite each other in the following electrolytic solution, and the current density is 1.
Electrolysis was carried out at 5 A/dm2. The electrolyte was passed through a cartridge filter with a thickness of 0.2 μ containing 8 Cuz particles.
Reflux was carried out at a rate of 5 times/hr. The electrolyte contains Cu2304
t509/, G 1H2304309/I, 1 mg/l of glue, and a liquid temperature of 48°C were used.

(2) In the above (1), an unglazed plate (thickness: 5 mtn) was placed between the anode and the cathode, and the electrolyte on the anode side was passed through a cartridge filter and refluxed at a rate of 25 times/hr.

(3> In (2) above, a cartridge filter containing 56 Cuz particles was used in place of the cartridge filter containing Cu2S particles.

(4) The cathode electrode @Cu recovered in (3) above was again used as an anode and electrolyzed again.

(5) In the above (2), a cartridge filter containing 3 Pb particles was used instead of the cartridge filter containing 8 Cuz particles.

(6) In (2) above, a cartridge filter filled with a 1:1 mixture of simple iodine and coconut husk charcoal was used instead of the cartridge filter containing 23 Cu particles.

(7) In the above (2), a cartridge filter filled with a 1:1 mixture of red selenium and X7 shigara charcoal was used in place of the Carr 1 to Tsutsuji filter containing 8 Cuz grains.

The cathode electrodeposited Cu and the raw material electrical Cu were analyzed according to (1) to (7) above. The results are shown in Table 1.

Next, according to (1) to (7) above, the cathode electrodeposited Cu was heated to 1100'C in an electric furnace using a nuclear reactor grade graphite crucible, melted, and then oxidized with air.
I raised it to DDm. Next, NH3 gas was blown in for reduction. This was repeated twice and then solidified. Subsequently, it was dissolved in an Ar gas flow, degassed in vacuum (0.051 orr) for 1 hour, and then solidified.

Analysis was limited to the nonmetallic components after oxidation-reduction and degassing. The results are shown in Table 2. All gas components in the table were analyzed by vacuum in-phase extraction at 950°C.

Next, the vacuum-degassed high-purity Cu shown in Table 2 was wire-drawn to a diameter of 25 μm and annealed. This was carried out using an ultrasonic thermocompression wire bonding machine (Nodel/1 manufactured by K&S).
123), a characteristic test was conducted as a bonding wire A7-.

The characteristics of the first bond (ball bond) were determined by examining the deformability of the ball on a 1μ thick evaporated Si wafer.
The bond (stay bond) is made of Cu alloy (Cu-0,1
5%Cr-0.2%Sn) and a pull test was performed. All bonding was performed in a 10% H2-N2 air flow at a temperature of 250°C, a load of 50g, and a bonding time of 50μs.
I did it with ec. These results were combined with electric Cu and commercially available A
A comparison with the u-line is shown in Table 3.

Table 3 D: Diameter after crimping As is clear from Tables 1 to 3, the production method of the present invention yields high-purity Cu with few impurities, especially AQ-containing groups, and is equivalent to or better than Au in terms of bonding properties, for example. It can be seen that it exhibits the characteristics of

This is because high-purity Cu is not only soft, but also easily recrystallized and easily deformed by the load during bonding, allowing complete bonding at the interface.

〔Effect of the invention〕

According to the present invention, mass productivity is higher than that of conventional methods, conductive properties with purity of 99.99 to 99.999% or more, softness,
High-purity copper with excellent low-temperature softening properties can be obtained, and the properties of sputter targets, printed circuits, etc., thin wire conductors, etc. can be significantly improved, resulting in remarkable industrial effects.

Claims (4)

[Claims] (1) An anode made of a Cu raw material and a cathode for electrodepositing Cu are installed opposite each other, and at least a part of the circulating electrolyte is transferred to Ag.
A method for producing high-purity copper characterized by contact treatment with an adsorbent substance and electrolytic treatment. (2) A sulfuric acid Cu sulfate aqueous solution is used as the electrolytic solution, and at least one of Cu, Pb sulfide, selenide, telluride, elemental sulfur, and selenium is used as the Ag adsorbing substance. manufacturing method for high-purity copper. (3) The anode and cathode are separated by an electrolyte-permeable diaphragm, and at least the electrolyte in the anode chamber is brought into contact with an Ag-adsorbing substance and returned to the cathode chamber. A method for producing high-purity copper. (4) An anode made of a Cu raw material and a cathode for electrodepositing Cu are installed opposite each other, and at least a part of the circulating electrolyte is transferred to Ag.
Electrodeposited C after contact treatment with adsorbent material and electrolytic treatment
A method for producing high-purity copper, which comprises dissolving u and subjecting it to oxidation treatment, followed by reduction treatment or re-dissolution in vacuum after the reduction treatment.