JPH0222431A - Copper wire rod for extra fine wire - Google Patents

Abstract

PURPOSE:To obtain the title wore rod having high electric conductivity, contg. less wear of a die and in which wire disconnection is hard to occur at the time of making copper into an extra fine wire by regulating the content of O, C and S in copper to the speific value. CONSTITUTION:In the copper wire rod for an extra fine wire, <=10ppm O and <=10ppm S are regulated and the balance is constituted of copper with inevitable impurities. The wire rod has improved wire drawability and is suitable for the manufacture of an extra fine wire having about <=0.1mm wire diameter. In the above copper wire rod, the reduction of the O content is permitted by an ordinary vacuum melting method, the regulation of the C content is obtd. by melting it in an inert gaseous atmosphere in the use of a graphite crucible and the reduction of S is furthermore attained by reelectrolyzing ordinary electric copper in a bath of nitric acid. The copper wire rod of pure copper obtd. by this method has high electric conductivity, is soft and with which the wear of a die is hard to occur. The wire rod can stably be subjected to wire drawing into about <=50mum extra fine wire without wire disconnection at low cost.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a copper wire material for ultra-fine wires used as thin copper wires or winding core wires for magnetic heads, etc. The present invention relates to a copper wire material for ultra-fine wires suitable for manufacturing ultra-fine wires with a diameter of 0.1 or less.

[Prior Art] In the field of thin copper wires and core wires for magnet wires used in electronic watches or flyback transformers, etc., with the recent development of electronic devices, ultrafine copper wires with wire diameters of 0.1 m+n or less have been developed. Demand for wires, especially ultrafine copper wires with a wire diameter of 50 μm or less, is rapidly increasing.

Therefore, there is a strong demand for reducing the manufacturing cost of this ultra-fine copper wire as well as reducing the wire diameter tolerance.

For this reason, there is an urgent need to develop a copper wire material that has less wear on the wire drawing die, suppresses expansion of the die diameter, and is less likely to break, even when a large amount of wire material is drawn into ultra-fine wire. It becomes.

[Problems to be solved by the invention] However, in general, pure silver has excellent conductivity and is softer than copper alloys, making wire drawing dies less likely to wear out, but it has low mechanical strength and is difficult to draw. There is a drawback that wire breakage is likely to occur during processing. In addition, although copper alloy has higher mechanical strength than pure copper and is less likely to break, it is harder than pure copper, so the die is more likely to wear out and the conductivity is low.

In this way, the wire rods used as conventional thin copper wires and core wires for magnet wires are required to have long lifespans with resistance to die wear, excellent conductivity, and resistance to wire breakage during wire drawing. It is not possible to satisfy both at the same time.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a copper wire material for ultra-fine wires that has high electrical conductivity, suppresses die wear during wire drawing during ultra-fine wire drawing, does not impair die life, and is less likely to break.

[Means for solving the problem] The copper wire material for ultrafine wire according to the present invention has a content of 0.
m or less, the total content of C and S is regulated to 10 ppm or less, and the remainder is copper and inevitable impurities.

[Function] The present invention focuses on the fact that pure copper has higher electrical conductivity than copper alloy, is softer and has less die wear, and in order to satisfy all the above requirements, it is necessary to make this pure copper wire material stretchable. This was done from the perspective of eliminating the drawback that wires tend to break during wire processing.

Therefore, as a result of repeated experiments in which various pure copper wire materials were drawn into ultra-fine wires with a wire diameter of 50 μm or less, the inventors of the present application found that non-metallic inclusions were often involved in the cause of wire breakage. I discovered that.

Nonmetallic inclusions include "oxides,""sulfides," and "carbides." Therefore, interstitial impurity elements that are constituent elements of these nonmetallic inclusions are 0. Focusing on S and C, prepare copper wire materials with various contents of these elements, draw each copper wire material to an ultra-fine wire with a wire diameter of 30 μm or less, and examine the wire drawability. The experiment was repeated.

As a result, when the C content is 110 PP or less and the total content of C and S is 10 ppm or less, it is possible to stably and continuously draw an ultrafine wire with a wire diameter of 30 μm or less. Ta.

Therefore, in the present invention, the zero content of pure copper wire is regulated to 10 ppm or less, and the total content of C and S is regulated to 10 ppm or less. This improves wire drawability and increases the wire diameter to 30
It becomes possible to stably draw even ultra-fine wires of ATM or less without causing wire breakage. When the content of O, C, and S exceeds such regulatory values, wire drawability deteriorates and wire breakage becomes more likely to occur.

In addition, since the present invention is a pure copper wire material without adding alloying elements, it has high conductivity, is soft, and the die is not easily worn.

In addition, the reduction of the 0 content is possible by ordinary vacuum melting, the adjustment of the C content is possible by melting in an inert gas atmosphere using a graphite crucible, and the reduction of S is usually possible by melting in an inert gas atmosphere using a graphite crucible. This is possible by re-electrolyzing the electrolytic steel in nitric acid.

[Example] Next, examples of the present invention will be specifically described.

Electrolytic copper with a purity of 99.95% by weight is placed in a vacuum atmosphere or N2
The cast rods of Examples 1 to 4 and Comparative Examples 1 to 3 were melted in a graphite crucible in a gas atmosphere, and the degree of vacuum was adjusted, or the oxygen partial pressure was adjusted to 0.1 to ITorr. Created. The composition of each cast rod is shown in Table 1 below.

Table 1 In Table 1, Comparative Example 4 is a cast rod of tough pitch copper produced by melting the electrolytic copper in the atmosphere. In addition, in Comparative Example 5, sb was added to the cast rod of Example 1 to 0.
．． This is a cast copper alloy rod containing 0.05% by weight. The diameter of each of these cast rods is 17 mm.

Next, each of the cast rods described above was repeatedly subjected to wire drawing and annealing to obtain an ultrafine wire with a wire diameter of 30 μm. The wire drawability in this wire drawing process, the degree of die wear, and the electrical conductivity of the obtained ultrafine wire (diameter 30 JJ, m) are shown in Table 2 below.

Table 2 However, in Table 2, the wire drawability column shows 1 kg of wire with wire diameters of 70) t m, 50 μm, 40 μm, and 3
When the wire was drawn to a wire diameter of 0 μm, the number of wire breaks was 0 when the wire broke, △ when it was 1 to 3, and × when it was 4 or more times. Further, in the die wear column, ○ indicates a case where the wire drawing amount is 30 kg or more until the die diameter, which was initially 30 μm, increases by 1 μm, and similarly, × indicates a case where the wire drawing amount is less than 25 kg.

As is clear from Table 2, Examples 1 to 1 have high electrical conductivity because they are pure copper wires, extremely little die wear, and excellent wire drawability. There was no wire breakage even when 1 kg of wire was drawn. On the other hand, since Comparative Example 5 is made of a copper alloy, the conductivity is low and the die wear is large. Furthermore, since Comparative Example 1 had a high O content and Comparative Example 2 had a high S content, wire drawability was poor, and wire breakage occurred during wire drawing up to a diameter of 40 μm. Furthermore, Comparative Example 3 has a high content of O and S, and Comparative Example 4 was dissolved in the atmosphere, so these interstitial impurity elements are extremely large, so the wire drawability is lower than that of Comparative Example 1. It is 1~1 which is even worse than .2.

[Effects of the Invention] According to the present invention, the content of 0 is 10 ppm or less, and the total content of C and S is 1. Since we have regulated the amount of interstitial impurity elements to less than Oppm, we can obtain a copper wire material for ultra-fine wires with excellent wire drawability while fully utilizing the advantages of pure copper wire material, such as high conductivity and low die wear. It will be done. For this reason,
Ultra-fine wires with a wire diameter of 30 μm or less can be stably mass-produced at low cost.

Claims (1)

[Claims] (1) A copper wire material for ultra-fine wires, characterized in that the content of O is regulated to 10 ppm or less, the total content of C and S is regulated to 10 ppm or less, and the remainder is copper and unavoidable impurities.