JPS62287508A - Copper wire for signal transmission - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Technical Field] The present invention relates to a copper wire for signal transmission used for internal wiring or inter-device wiring such as audio equipment, video equipment, and computers. be.

[Prior art and its problems] Conventionally, TPO (tough pitch core) annealed copper wire has been used as a conductor for audio equipment, and even higher grade products have O.
FC (oxygen-free copper) annealed copper wire has been used, but recently, for some high-end audio applications, the crystal grains of FC copper wire are enlarged by heat treatment and then drawn, and the crystal grains are made larger in the length direction. A hard copper wire oriented in
Publication No. 08).

However, although the crystal grains are enlarged, the technical limit is to make the grain size about 115 to 1/3 of the wire diameter, and the state before wire drawing is still polycrystalline. Therefore, even if the polycrystalline wire is drawn and the crystal grains are stretched in the longitudinal direction, the grain boundaries, that is, the planar defects do not disappear, but are merely dispersed in the longitudinal direction. For this reason, in the cross section of the manufactured copper wire, countless planar defects, which were originally grain boundaries, now exist in the form of dots. Naturally, it is thought that these dotted grain boundaries act as capacitance due to the presence of Cu 20 and the like, as has been conventionally said. Therefore, OFC hard copper wire was still not sufficient as a conductor for audio equipment.

Further, since conventional copper wire is drawn from an ingot prepared using a cooling mold, it has numerous defects on its surface and inside. In other words, on the surface, there are defects such as scratches and rough skin caused by rubbing between the mold and the ingot, and on the inside, there are defects such as cracks and blowholes that occur during solidification and shrinkage. Cheap. Of course, internal defects are not desirable, but surface defects are also not desirable for high frequency signal current flowing near the surface of the wire, and t? When used as an A-line conductor, wires with surface defects come into contact with each other to form a complicated circuit, causing signal waveform distortion and attenuation. Therefore, a copper wire for audio equipment is also required to have fewer surface defects and internal defects.

Furthermore, the above-mentioned ○FC hard copper wire for high-grade audio is used as is after wire drawing, so compared to OFC soft copper wire, it is less susceptible to atomic vacancies (point defects) and dislocations (linear defects).
density is extremely high. Therefore, like grain boundaries, these defects also cause phase differences and attenuation of signals, which is undesirable.

Although the problems with W4 wires for audio equipment have been described above, similar problems also apply to copper wires for signal transmission in electronic equipment such as video equipment and computers.

[Means for solving problems and their effects]

In view of the problems of the prior art as described above, the present invention provides a high quality copper wire for signal transmission free of various defects.

The signal transmission copper wire of the present invention is obtained by wire-drawing an oxygen-free copper ingot with a unidirectionally solidified structure, and then annealed to reduce electrical resistance without causing recrystallization. This is what happens.

Oxygen-free copper ingots having a unidirectional solidification structure can be produced by a casting method using a heated mold (for example, Japanese Patent Publication No. 56-46265 11i). This method uses a mold and a solidified shell (
Since the molten metal exists between the two skins and the two do not come into direct contact, an ingot with a mirror-like surface without any skin breakage or rough casting surface can be obtained. In addition, the ingot obtained by this casting method takes a solidification form called unidirectional solidification and has a single crystal structure, so the crystal grains are different from those of conventional materials, as well as elongation and vA.
Although high-temperature annealing was performed during processing, the size is approximately 100,000 times larger. As described above, the unidirectionally solidified Mi woven oxygen-free copper ingot has no surface defects or internal defects, and can be said to be the optimal material for signal transmission copper wires.

The unidirectionally solidified Mi woven oxygen-free copper ingot is extremely excellent as a material as mentioned above, but when it is drawn into a wire rod, it has more atomic vacancies and translocations than the raw material. The density of increases. These defects cause scattering of electrons, causing a phase difference or attenuation of high-frequency signals. Therefore, the atomic vacancies increased by cold working,
As a result of examining various means to reduce dislocation, we found that although normal annealing produces recrystallized grains (planar defects), if held at a lower temperature for an appropriate time, recrystallization does not occur but electrical resistance decreases. This phenomenon was observed, and it was found that atomic vacancies and dislocations decreased.

Based on this knowledge, the present invention aims to obtain high-quality copper wire for signal transmission by annealing the above-mentioned wire in such a way that the electrical resistance decreases without causing recrystallization. It was a success.

It is appropriate to perform the above annealing at a temperature of 120 to 180°C, and at 180°C it may take only a few seconds, but as the temperature decreases, the annealing time needs to be longer. Alternatively, the coating may be carried out at the time of extrusion coating or painting of the insulating material.

〔Example〕

A unidirectionally solidified Mi woven oxygen-free copper ingot with a diameter of 151 mm was cast using a mold heating method, and this was cold wire-drawn to a diameter of 0.1 mm.
A wire rod of 8 mI++ was manufactured. The conductivity of this wire is 10
1.5%, atomic vacancy/dislocation density is 1011 pieces/cm2,
The length of the crystal grains was ~1600 m/piece, there were no internal defects such as blowholes, and the surface quality was extremely good.

Next, the above wire rod was annealed at 180° C. to obtain a copper wire for signal transmission of the present invention. The yield strength decreased by 8% due to annealing. The α electric rate increased to 102.1%, and the vacancy/dislocation density decreased significantly to 10'/cra'.The length of the crystal grains and other aspects were the same as the wire before annealing. .

On the other hand, a polycrystalline oxygen-free copper ingot cast using the normal mold cooling method was wire-drawn to a diameter of 1.61, then annealed to enlarge the crystal grains to about 173 of the wire diameter, and then further wire-drawn. The diameter of the crystal grains oriented in the longitudinal direction is 0.1
An 8 mm OFC hard copper wire was obtained. The conductivity of this hard copper wire is 1
．． 00.2%, atomic vacancy/dislocation density is 10"/cm"
The length of the crystal grains was 0.03 m/piece. In addition, blowhole shrinkage holes from casting remained inside, and surface defects from casting remained on the surface.

For comparison, a polycrystalline oxygen-free copper ingot cast using a normal mold cooling method was cold drawn to a diameter of 0.18 mm, and then annealed at 180°C in the same manner as in the present invention. Obtained. Due to annealing, the yield strength decreased by 10% compared to before annealing. The conductivity of this copper wire was 101.1% (annealed...1% higher than I), the atomic vacancy/dislocation density was 108/am", and the length of crystal grains was 0.01 m/piece. Blowhole shrinkage holes from casting remained inside, and surface defects from casting remained on the surface.

As is clear from the above experimental results, the signal transmission copper wire of the present invention has significantly fewer atomic vacancies and dislocations than the conventional OFC hard copper wire, and has almost no internal defects or surface defects. Therefore, by using this, you can obtain clear audio and images with almost no signal distortion.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain a copper wire for signal transmission that has no internal defects or surface defects due to casting and has an extremely low density of atomic vacancies and dislocations. Therefore, by using this copper wire for signal transmission, it is possible to minimize signal phase distortion and attenuation, and it is possible to obtain clear sound and images in audio and video equipment, and to improve reliability in systems such as computers. can be configured.

Claims (1)

[Claims] A signal transmission copper wire made by drawing an oxygen-free copper ingot with a unidirectionally solidified structure and annealing the wire to reduce electrical resistance without causing recrystallization.