JPH07214232A - Production of high-purity copper ingot - Google Patents

Abstract

PURPOSE:To produce a high-purity copper ingot contg. Fe and Si at extremely low ratios by using a carbon crucible, nozzle and casting mold. CONSTITUTION:This method comprises producing the high-purity copper ingot by melting a high-purity copper raw material, such as electric copper, by using the carbon crucible and passing the resulted high-purity copper melt through the carbon nozzle into the carbon casting mold, thereby casting the ingot. The carbon crucible, the carbon nozzle and the carbon casting mold are previously heat treated under a condition of holding at 800 to 1120 deg.C in a non-oxidizing atmosphere before the high-purity copper raw material is melted and cast. The high-purity copper ingot is produced by using the heat treated carbon crucible, the carbon nozzle and the carbon casting mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an audio wire,
The present invention relates to a method for producing a high-purity copper ingot for producing a high-purity copper wire rod such as a bonding wire of a semiconductor device or a superconducting stabilizer.

[0002]

2. Description of the Related Art Generally, 99.9 is used for audio wires, bonding wires for semiconductor devices, and superconducting stabilizers.
A high-purity copper wire of 999% by weight (hereinafter referred to as 6N) or more is used.

These high purity copper wires of 6N or more are manufactured by first producing high purity copper ingots of 6N or more, rolling the high purity copper ingot, repeating wire drawing and annealing, and finally drawing a predetermined fine wire by drawing. Produced a high purity copper wire having a diameter.

Conventionally, high purity copper ingots of 6N or more are
It is manufactured by melting 6 N or more high-purity electrolytic copper in a high-purity alumina crucible in a vacuum or in an inert gas atmosphere, and casting the resulting melt in a high-purity alumina mold through a high-purity alumina nozzle.

However, although a high-purity copper ingot manufactured by using a high-purity alumina crucible, a high-purity alumina nozzle and a high-purity alumina mold can maintain a purity substantially equal to that of electrolytic copper, Alumina crucibles, nozzles, molds and the like are easily cracked, easily cast, and expensive, so that the price of the high-purity copper wire obtained is also high.

Therefore, a commercially available high-purity carbon crucible is usually used to melt high-purity electrolytic copper, and the resulting molten metal is used as a high-purity copper ingot using a commercially available high-purity carbon nozzle and carbon mold. Was being manufactured.

[0007]

However, using a commercially available high-purity carbon crucible, a carbon nozzle, and a carbon mold (these are collectively referred to as carbon furnace materials), high-purity electrolytic copper is used. When a high-purity ingot is manufactured by melting and casting, Fe contained in the carbon furnace material is
And Si elute and dissolve in molten copper, and the obtained high-purity ingot contains 0.5 ppm of Fe and Si, respectively.
Inclusion to some extent was unavoidable.

This is because even if Fe and Si are dissolved using high-purity electrolytic copper as a raw material that cannot be detected by a mass spectrometer, the contents of Fe and Si contained in the obtained high-purity copper ingot are high. It has been confirmed that the content of each is 0.5 ppm or more.

If the high-purity copper wire contains 0.5 ppm or more of Fe and Si, respectively, the residual resistance ratio (ratio of electric resistance ρ _{298 K} at room temperature to electric resistance ρ _{4.2 K} at liquid helium temperature ρ _{298 K} / ρ _4.2). Defined by _K , hereafter RRR
, And the use of such a high-purity wire with a low RRR for an audio wire significantly increases noise generation.
Even if it is used as a superconducting stabilizer, the electric resistance under cryogenic temperature becomes large and the desired effect cannot be obtained, and even when it is used as a bonding wire of a semiconductor device, the adhesiveness becomes poor.

Therefore, a wire material that can be used as an audio wire, a superconducting stabilizing material, a bonding wire, etc., must have an RRR of 10,000 or more, and 6N is required to obtain an RRR of 10,000 or more. And above, and the contents of Fe and Si are each 0.1
Since it is necessary to be less than or equal to ppm, there has been a demand for technological development capable of inexpensively producing a high-purity copper ingot with Fe and Si contents of less than or equal to 0.1 ppm using a carbon furnace material. .

[0011]

Therefore, the present inventors have
As a result of conducting research to manufacture high-purity copper ingots each containing Fe and Si of 0.1 ppm or less by using a carbon furnace material, (a) high-purity electrolytic copper was preheated in a non-oxidizing atmosphere at a temperature : When a carbon furnace material is heat-treated at 800 to 1120 ° C. (preferably 900 to 1050 ° C.) and an ingot is manufactured using this heat-treated carbon furnace material, Fe and S contained in the carbon furnace material
i and impurities do not dissolve in molten copper, and Fe and S
A high-purity copper ingot each having an i impurity content of 0.1 ppm or less is obtained. (b) A part of the carbon furnace material may be replaced with a commercially available alumina nozzle and / or an alumina mold, The results of such research were obtained.

The present invention has been made on the basis of the above research results. (1) In a method for producing a high-purity copper ingot by melting and casting a high-purity copper raw material using a carbon furnace material, Before melting and casting the pure copper raw material,
Carbon furnace material in advance in a non-oxidizing atmosphere, temperature: 800
˜1120 ° C. (preferably 900 to 1050 ° C.), and a high-purity copper ingot is produced by using the heat-treated carbon furnace material to produce a high-purity copper ingot. (2) A high purity copper ingot is manufactured by replacing a part of the heat-treated carbon furnace material of (1) with an alumina nozzle and / or an alumina mold to manufacture a high purity copper ingot. It is characterized by the law.

[0013]

【Example】

Examples 1 to 7, Comparative Examples 1 and 2 and Conventional Example, high-purity electrolytic copper was prepared, and this high-purity electrolytic copper was GD-MS.
As a result of analysis by (mass spectrometer), the analysis results as shown in Table 1 were obtained.

[0014]

[Table 1]

On the other hand, a commercially available high-purity graphite crucible, a high-purity graphite nozzle and a high-purity graphite mold were prepared and heat-treated under the conditions shown in Table 2, and the heat-treated high-purity graphite crucible was used. Examples 1 to 7 and Comparative Examples 1 to 1 by melting at 1150 ° C. in a vacuum atmosphere and casting the molten metal using the heat-treated high-purity graphite nozzle and mold to produce a high-purity copper ingot. 2 was carried out.

Further, for comparison, the above-mentioned commercially available high-purity graphite crucible, high-purity graphite nozzle and high-purity graphite mold are used without heat treatment to melt-cast the high-purity electrolytic copper to obtain high-purity copper. A conventional example was carried out by manufacturing an ingot.

The high-purity copper ingots obtained in Examples 1 to 7, Comparative Examples 1 and 2 and Conventional Example were analyzed by GD-MS (mass spectrometer), and the analysis results are shown in Table 2.

[0018]

[Table 2]

From the analysis results of the high-purity copper ingots shown in Table 2, Example 1 manufactured using a high-purity graphite crucible, a nozzle and a mold which were heat-treated in a non-oxidizing atmosphere at a temperature of 800 to 1120 ° C. It can be seen that the high-purity copper ingots of Nos. 7 to 7 contain less Fe and Si than the conventional high-purity copper ingots manufactured using the high-purity graphite crucible, the nozzle, and the mold that are not heat-treated. Further, as shown in Comparative Examples 1 and 2, it is understood that even if the high-purity graphite crucible, the nozzle and the mold are heat-treated at a temperature outside the range of 800 to 1120 ° C, a sufficient effect cannot be obtained.

Examples 8 to 10 In addition to a high-purity graphite crucible, a nozzle and a mold heat-treated under the conditions of Example 4 in Table 2, a commercially available high-purity alumina nozzle and mold were prepared, and these crucible, nozzle and Examples 8 to 10 shown in Table 3 by producing high purity copper ingots from the high purity electrolytic copper of Table 1 using a mold
10 is carried out, and the obtained high-purity copper ingot is subjected to GD-M.
It analyzed by S (mass spectrometer), and the analysis result was shown in Table 3.

[0021]

[Table 3]

From Examples 8 to 10 in Table 3, at least a heat-treated graphite crucible was used for melting, and a commercially available high-purity alumina nozzle and / or a mold were used, but the heat treatment in Table 2 was not performed. Fe and Si compared to the conventional example using a high-purity graphite crucible, nozzle and mold
It can be seen that a high-purity copper ingot with a low content can be obtained.

[0023]

As described above, even if high-purity electrolytic copper, which has hardly detected Fe and Si, is used, a high-purity copper ingot produced by using a normal carbon furnace material is used. Fe and Si are contained in an increased amount, and a wire obtained by rolling and drawing this ingot also contained a large amount of Fe and Si, which caused various electrical troubles. According to the method of the present invention in which a furnace material is heat-treated before being melt-cast, a high-purity copper ingot with an extremely low Fe and Si content can be produced, and a wire rod having an RRR of 10,000 or more can be provided at low cost. It is possible to bring about excellent effects in industry.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideyuki Ikenoya 1-297 Kitabukuro-cho, Omiya-shi, Saitama Central Research Laboratory, Mitsubishi Materiality Co., Ltd.

Claims (5)

[Claims] 1. A method for producing a high-purity copper ingot by melting a high-purity copper raw material using a carbon crucible, casting the obtained high-purity copper melt in a carbon mold through a carbon nozzle, Before melting and casting the pure copper raw material, the carbon crucible, the carbon nozzle, and the carbon mold are heat-treated in advance in a non-oxidizing atmosphere at a temperature of 800 to 1120 ° C. A method for producing a high-purity copper ingot, which comprises producing a high-purity copper ingot using a crucible made of carbon, a nozzle made of carbon, and a mold made of carbon. 2. A method for producing a high-purity copper ingot by melting a high-purity copper raw material using a carbon crucible and casting the obtained high-purity copper melt into a high-purity alumina mold through a high-purity alumina nozzle. In the above, before melting the high-purity copper raw material, the carbon crucible was previously heated in a non-oxidizing atmosphere at a temperature of 800 to 1120 ° C.
A method for producing a high-purity copper ingot, characterized in that the high-purity copper raw material is melted using the heat-treated carbon crucible. 3. A method for producing a high-purity copper ingot by melting a high-purity copper raw material using a carbon crucible, casting the obtained high-purity copper melt into a high-purity alumina mold through a carbon nozzle, Before the high-purity copper raw material is melted and cast, the carbon crucible and the carbon nozzle are heat-treated in advance in a non-oxidizing atmosphere at a temperature of 800 to 1120 ° C., and the heat-treated carbon crucible is heated. And a method for producing a high-purity copper ingot, which comprises melting and casting using a carbon nozzle. 4. A method for producing a high-purity copper ingot by melting a high-purity copper raw material using a carbon crucible and casting the obtained high-purity copper molten metal into a high-purity carbon mold through a high-purity alumina nozzle. In the above, before melting and casting the high-purity copper raw material, the carbon crucible and the carbon mold are preliminarily heat-treated in a non-oxidizing atmosphere at a temperature of 800 to 1120 ° C. A method for producing a high-purity copper ingot, which comprises melting and casting using a crucible made of carbon and a mold made of carbon. 5. The heat treatment temperature of the carbon crucible, the carbon nozzle and the carbon mold is 900 to 10.
The temperature is in the range of 50 ° C., and
3. The method for producing a high purity copper ingot according to 3 or 4.