Sumitomo Electric Industries, Limited

Tadanori Sano

Yoshihiro Nakai

Kazuo Sawada

Kenji Miyazaki

A method of manufacturing an improved conductor wire, especially for use as wiring in audio/video devices is disclosed. The conductor consists of copper having a high purity of at least 99.9 wt. %. High purity copper starting material is formed as a rod which is then heat treated at a temperature in the range of 400.degree. C. to 700.degree. C. for 1 minute to 24 hours. The heat treated rod is then cold worked with a reduction in area of at least 65%. This method provides an electrical conductor wire which avoids irregularities of electron density and thereby eliminates phase differences in a high frequency signal, such as an audio or video signal, passing through the wire to obtain clear transmission and reproduction of an audio sound or video image. The method of the invention increases the residual resistance ratio of the conductor wire to at least 179 or by at least 20% as compared to a conventional conductor which is not heat treated according to the invention. Finally, in a quality control method, the expected audio and video transmission characteristics of a manufactured conductor wire can be evaluated by determining the residual resistance ratio of the conductor wire.

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Osaka, Japan

Tadanori Sano