JPH0747809B2 - Manufacturing method of high-purity copper wire consisting of coarse crystal grains - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-purity copper wire composed of coarse crystal grains.

[0002]

2. Description of the Related Art Conventionally, high-purity copper has been used not only for electronics such as bonding wires and metal / semiconductor contacts, but also for conductive materials such as superconductivity, ultra-high voltage, ultra-high vacuum or acoustic equipment, and cooling media for cryogenic equipment. Or in many advanced technology fields such as high-proof laser mirrors,
It has been widely used as one of the materials that control its performance. In particular, it is known that the quality of copper affects the sound quality of cable wires, lead wires, cord parts, terminals, connectors, etc., which are conductive materials for audio equipment.

For example, in a copper wire used for wiring audio equipment and visual equipment, the purity and crystal grains of copper particularly affect sound quality. That is, the lower the content of sulfur as a non-metallic inclusion in the copper wire and the higher conductivity of silver, and the smaller the number of crystal grain boundaries (the coarser the crystal grains are), the less the deterioration of sound quality. Become.

Conventionally, a high-purity copper wire has been manufactured by using 99.
Using 99% or higher high-purity copper, the purity is 99.99 by the method of manufacturing a wire rod by the hot working method or the casting method.
%, There has been used a method of forming a cast copper wire of at least 100% and cold drawing it to a desired wire diameter. According to the former method, hot working at a temperature higher than the recrystallization temperature is repeated to obtain a recrystallized material in which relatively fine crystal grains are aggregated. Crystals can be sufficiently grown by annealing. However, if hot working is adopted, it is inevitable that impurities will be mixed into the product, and a wire rod in which the purity of the material is maintained cannot be manufactured. On the other hand, according to the latter method, since hot working is not performed, it is possible to avoid inclusion of impurities in the product, but since a relatively large cast structure with different crystal orientations is cold worked at a temperature below the recrystallization temperature. However, it was not possible to give a uniform strain to each crystal grain. Therefore, even if this is annealed at a high temperature, the recrystallization behavior in each crystal grain is different from each other, and it has been extremely difficult to obtain a structure composed of only coarse crystal grains.

Further, Japanese Patent Application Nos. 1-269015 and 1-269016 disclose a method for producing a high-purity copper wire composed of coarse crystal grains. According to the methods disclosed in these publications, Although we have achieved the objectives of preventing impurities from entering the product and coarsening the crystal grains,
There is a problem that the wire rods are welded to each other.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a high-purity copper wire made of coarse crystal grains which retains the high-purity characteristics of the high-purity copper used as a material. It is an object of the present invention to provide a method capable of manufacturing wires without welding them together.

[0007]

Means for Solving the Problems The inventors of the present invention have made earnest studies to solve the above-mentioned problems. As a result, primary cold wire drawing and suitable atmosphere without hot working using a high-purity cast material. By performing intermediate annealing below, fine primary recrystallization with a specific orientation is obtained, and secondary cold wire drawing and continuous annealing in a suitable atmosphere for a predetermined period of time make it coarse with high purity. It was found that the secondary recrystallization described above was obtained, and the present invention could be achieved.

That is, according to the present invention, a casting material made of high-purity copper having a total content of silver and sulfur of 0.5 ppm or less and a purity of 99.9999% or more is drawn by cold drawing without hot working. A method of obtaining a wire rod that retains the high purity by processing, wherein the casting material is subjected to primary cold wire drawing at a working rate of 60% to 99.9%, and then in an inert gas atmosphere or in a vacuum. After intermediate annealing in a temperature range of 150 ° C to 600 ° C, and then secondary cold drawing to the final product wire diameter, in an inert gas atmosphere or in a vacuum, in a temperature range of 450 ° C to 950 ° C for 2 seconds. The present invention provides a method for producing a high-purity copper wire made of coarse crystal grains, characterized by performing continuous annealing.

The intermediate annealing in the present invention is preferably carried out by holding at the annealing temperature for 10 to 180 minutes and then rapidly cooling, whereby a higher quality product can be obtained. In the present invention, when it is difficult to reduce the final product wire diameter by two cold drawing processes of primary cold drawing and secondary cold drawing, after the second cold drawing, ,
After performing the intermediate annealing similar to the above, perform the final cold wire drawing,
Further, final annealing may be performed.

[0010]

In the present invention, a wire having a high purity casting material as described above is obtained by annealing and cold drawing in a suitable atmosphere (in vacuum or in an inert gas atmosphere) without hot working. Therefore, the mixture of impurities and the oxidation are suppressed, the total content of silver and sulfur is 0.5 ppm or less, and a high-purity copper wire having a purity of 99.9999% or more can be obtained. When the annealing step is unavoidably performed in the air, it is preferable to remove the oxide film in the pickling step.

According to the present invention, a cast material having a cast structure (preferably continuous cast material) is not subjected to hot working,
By performing cold wire drawing (primary cold wire drawing) processing and intermediate annealing, the cast structure is completely crushed and a fine recrystallized structure (primary recrystallization) having a specific orientation is obtained. The finer the primary recrystallization, the easier the control of the crystal orientation and the coarsening in the subsequent steps, so that the working rate of the primary cold drawing must be sufficiently high. However, if the working rate exceeds 99.9%, the risk of disconnection increases in the intermediate annealing, and if it is less than 60%, the recrystallization temperature in the intermediate annealing becomes high and fine recrystallized grains can be sufficiently obtained. Therefore, the range is set to 60 to 99.9%.

The annealing temperature in the intermediate annealing is 150.
Since ℃ is the lower limit of the annealing temperature of high-purity copper, a temperature higher than that is required, but if it exceeds 600 ° C., the crystal grains increase sharply and secondary recrystallization is formed at this stage. The range was limited to 150 to 600 ° C. Further, the time of holding at the above temperature is also related to the annealing temperature, but within 10 minutes, sufficient recrystallization cannot be obtained, and if it is too long, the crystal grains become coarse, so that 10 minutes to 180 minutes. And After annealing under the above conditions, the growth of crystal grains can be suppressed by quenching from the intermediate annealing temperature,
The obtained fine primary recrystallization structure can be more reliably maintained.

Next, the obtained fine primary recrystallized annealed material is subjected to cold wire drawing (secondary cold wire drawing) up to the product wire diameter to give an appropriate strain, and further The secondary recrystallized grains are coarsened by carrying out continuous annealing (final annealing) for 2 seconds or more at a temperature of 450 ° C. or higher under an active gas atmosphere or under vacuum. Since the crystal grains are coarsened in this way, it is also possible to obtain a wire rod in which the maximum diameter of the crystal exceeds the wire diameter in the case of producing a thin wire.

The working ratio of the secondary cold wire drawing is
Depending on the final wire diameter, 80% or more is sufficient. In addition, the temperature in the final annealing is in the range of 450 to 950 ° C because the wire may soften and break if the temperature exceeds 950 ° C.

Since the final annealing in the present invention is performed by a continuous method rather than a batch method, the adhesion between the wire rods during the final annealing step is reduced, and the wire rods are prevented from being welded to each other. .

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited by the following examples.

[0017]

Example 1 An example of a method for producing a high-purity copper wire made of coarse crystal grains of the present invention will be described below.

First, the purity produced by continuous casting is 9
Cold drawing (primary cold drawing) of high purity copper casting wire with a total content of silver and sulfur of 0.5ppm or less to 9.9999% or more up to a diameter of 2 mm (working rate of about 96.7%) Processed,
Annealing (intermediate annealing) was performed at 300 ° C. for 1 hour in a nitrogen gas atmosphere. The cooling from the annealing temperature of the wire rod in this intermediate annealing was performed by a water cooling method.

Next, the above-mentioned annealed material is cold-drawn (secondary cold-drawn) to a diameter of 120 μm (working rate of about 99.6%) and continuously annealed at 650 ° C. for 8 seconds in a nitrogen gas atmosphere. (Final annealing) was performed.

When the crystal structure of the wire thus obtained was examined, it was found to be huge crystal grains (coarse crystal grains) having an average crystal grain size of 60 μm. FIG. 1 shows a copy of a micrograph of a cross section of the obtained wire rod which is orthogonal to the wire axis.

[0021]

Example 2 Another example of the method for producing a high-purity copper wire made of coarse crystal grains of the present invention will be described below.

In this example, the intermediate annealing was carried out in the same manner as in Example 1 except that the wire material was cooled from the annealing temperature and was gradually cooled without being rapidly cooled.

As a result, when the crystal structure of the obtained final wire was examined, it was found to be huge crystal grains (coarse crystal grains) having an average crystal grain size of 50 μm. FIG. 2 shows a photomicrograph of a cross section of the obtained wire rod which is orthogonal to the line axis.

[0024]

COMPARATIVE EXAMPLE 1 A comparative example to the method for producing a high-purity copper wire made of coarse crystal grains of the present invention is shown below.

The same procedure as in Example 1 was carried out except that continuous annealing (final annealing) was performed at 400 ° C. for 8 seconds in a nitrogen gas atmosphere.

As a result, when the crystal structure of the obtained final wire was examined, the growth of crystal grains was poor and the average crystal grain size was 1
It was only 0 μm, and it was a mixed grain.

[0027]

Comparative Example 2 Another comparative example with respect to the method for producing a high-purity copper wire made of coarse crystal grains of the present invention is shown below. It carried out like Example 1 except having performed intermediate annealing at 100 ° C x 1 hour under nitrogen gas atmosphere.

As a result, when the crystal structure of the obtained final wire was examined, it was found that the average crystal grain size was 2 μm and that it was a fine crystal grain.

[0029]

COMPARATIVE EXAMPLE 3 Yet another comparative example with respect to the method for producing a high-purity copper wire made of coarse crystal grains of the present invention is shown below.

The annealed material obtained after the intermediate annealing has a diameter of 7.5.
The same procedure as in Example 1 was performed except that the primary cold drawing was performed up to mm (working rate: about 54%).

As a result, when the crystal structure of the obtained final wire was examined, it was found to be fine crystal grains having an average crystal grain size of 3 to 4 μm.

[0032]

COMPARATIVE EXAMPLE 4 Yet another comparative example with respect to the method for producing a high-purity copper wire made of coarse crystal grains of the present invention is shown below.

The procedure of Example 1 was repeated except that the intermediate annealing was not performed.

As a result, when the crystal structure of the obtained final wire was examined, it was found that the average crystal grain size was 2 μm. FIG. 3 shows a copy of a micrograph of the cross section of the wire rod obtained, which is orthogonal to the wire axis.

[0035]

As a result of the development of the present invention, the total content of silver and sulfur is 0.5 ppm or less, and the purity is 99.9999%.
It has become possible to manufacture a high-purity copper wire composed of coarse crystal grains while maintaining the ultra-high-purity characteristics of the above materials. Further, according to the present invention, the wires are not welded to each other, so that the productivity is remarkably improved.

[Brief description of drawings]

FIG. 1 shows a crystal structure of a high-purity copper wire produced based on an example of a method for producing a high-purity copper wire composed of coarse crystal grains of the present invention, and is a micrograph of a cross section orthogonal to a line axis. Is a copy of.

FIG. 2 shows a crystal structure of a high-purity copper wire manufactured according to another example of the method for manufacturing a high-purity copper wire composed of coarse crystal grains of the present invention, showing a cross-section of a cross section orthogonal to the line axis. It is a copy of a micrograph.

FIG. 3 shows a crystal structure of a high-purity copper wire manufactured based on a comparative example of a method for manufacturing a high-purity copper wire composed of coarse crystal grains of the present invention, and is a microscope of a cross section orthogonal to a line axis. It is a copy of a photo.

[Explanation of symbols]

 1 crystal grain

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Claims (3)

[Claims] 1. A casting material made of high-purity copper having a total content of silver and sulfur of 0.5 ppm or less and a purity of 99.9999% or more is subjected to cold wire drawing without hot working. A method for obtaining a wire having a high purity, wherein the casting material is subjected to primary cold wire drawing at a working rate of 60% to 99.9%, and then 150 ° C to 6 ° C in an inert gas atmosphere or in a vacuum.
After intermediate annealing in the temperature range of 00 ° C, then secondary cold drawing to the final product wire diameter, continuous annealing in the temperature range of 450 ° C to 950 ° C for 2 seconds or more in an inert gas atmosphere or in vacuum. A method for producing a high-purity copper wire composed of coarse crystal grains, characterized in that 2. A casting material made of high-purity copper having a total content of silver and sulfur of 0.5 ppm or less and a purity of 99.9999% or more is subjected to cold wire drawing without hot working. A method for obtaining a wire having a high purity, wherein the casting material is subjected to primary cold wire drawing at a working rate of 60% to 99.9%, and then 150 ° C to 6 ° C in an inert gas atmosphere or in a vacuum.
Intermediate annealing in a temperature range of 00 ° C, and then a working rate of 60
% 99.9% secondary cold drawing, then secondary intermediate annealing in the temperature range of 150 ° C to 600 ° C in an inert gas atmosphere or in vacuum, and then tertiary cold drawing until the final product. After processing, in an inert gas atmosphere or in vacuum, 450
A method for producing a high-purity copper wire composed of coarse crystal grains, which comprises continuously annealing for 2 seconds or more in a temperature range of ℃ to 950 ℃. 3. The method for producing a high-purity copper wire according to claim 1, wherein the intermediate annealing is performed by holding at the annealing temperature for 10 minutes to 180 minutes and then quenching.