Method of producing electrical conductor

Abstract

A method of producing an electrical conductor is described. The electrical conductor is made of an oxygen-free copper material having an oxygen content of not more than 50 ppm, wherein copper crystals constituting the copper material are giant crystals. These giant copper crystals are formed by heating the copper material in an inert atmosphere maintained at a temperature exceeding 800° C., but below the melting point of copper for at least 15 minutes.

We claim: 
     
       1. A method for improving multi-frequency signal transmission characteristics of an electrical conductor consisting essentially of an oxygen-free copper material having an oxygen content of not more than 50 ppm, comprising the steps of: heating the electrical conductor made of an oxygen-free copper material having an oxygen content of not more than 50 ppm in an inert atmosphere at a temperature exceeding 800° C. but below the melting point of copper for at least 15 minutes to form giant copper crystals .Iadd.which have an average crystal diameter of at least 400 μm.Iaddend..   
     
     
       2. The method as claimed in claim 1, wherein the oxygen content of said oxygen-free copper material is not more than 15 ppm. 
     
     
       3. The method as claimed in claim 1, wherein the oxygen content of said oxygen-free copper material is not more than 5 ppm. 
     
     
       4. The method as claimed in claim 1, wherein said oxygen-free copper material is heated in an inert gas atomosphere at a temperature exceeding 850° C. but below the melting point of copper for at least 30 minutes to form giant copper crystals. 
     
     
       5. A method for improving multi-frequency signal transmission characteristics of an electrical conductor consisting essentially of an oxygen-free copper material having an oxygen content of not more than 50 ppm, comprising the steps of: heating the electrical conductor made of an oxygen-free copper material having an oxygen content of not more than 50 ppm in an inert atmosphere at a temperature exceeding 800° C. but below the melting point of copper for at least 15 minutes to form giant copper crystals, and orienting the thus-formed giant copper crystals in a linear orientation by stretching said conductor in the lengthwise direction thereof.   
     
     
       6. The method as claimed in claim 5, wherein the oxygen content of said oxygen-free copper material is not more than 15 ppm. 
     
     
       7. The method as claimed in claim 5, wherein the oxygen content of said oxygen-free copper material is not more than 5 ppm. 
     
     
       8. The method as claimed in claim 5, wherein said oxygen-free copper material is heated in an inert gas atmosphere at a temperature exceeding 850° C. but below the melting point of copper for at least 30 minutes to form giant copper crystals. 
     
     
       9. The method as claimed in .[.claime.]. .Iadd.claim .Iaddend.5, wherein said giant copper crystals are cold stretched by cold drawing. 
     
     
       10. The method as claimed in claim 5, wherein said giant copper crystals are stretched by cold rolling. .Iadd. 
     
     
       11.  A method for producing a copper electrical conductor consisting essentially of oxygen-free copper having an oxygen content of not more than 50 ppm, said electrical conductor being characterized by improved multi-frequency signal transmission characteristics and being usable for multi-frequency signal transmission for an electrical apparatus, comprising (A) forming giant crystal grains which have an average crystal diameter of at least 400 μm in said oxygen-free copper electrical conductor and   (B) then stretching said oxygen-free copper electrical conductor in its lengthwise direction to form an oxygen-free copper electrical conductor having giant crystals oriented in the linear direction. .Iaddend. .Iadd.   
     
     
       12.  The method as claimed in claim 11 wherein said step (A) of forming giant crystal grains is carried out by heating said conductor at a temperature exceeding 800° C. .Iaddend. .Iadd.13. The method as claimed in claim 12 wherein said step (A) of forming giant crystal grains is carried out in an inert atmosphere. .Iaddend.