Nippon Mining Co., Ltd.

Japan Energy Corporation

Yoshio Kawasumi

Masanori Kato

Chikara Tominaga

Takashi Ogata

Kanji Tanaka

Haruki Sato

A copper foil for printed circuits including a thermal oxidation-resistant treated layer (e.g., Zn--Ni or Zn--Co alloy plating) formed on the shiny side of the foil and a Cr-base anticorrosive treated layer (e.g., chromate film, mixed film of chromium oxide and zinc and/or zinc oxide, or both) formed further thereon, characterized in that a copper plating layer or an etched surface is provided before forming the thermal oxidation resistant treated layer. The copper plating or etching permits the shiny side to be completely covered with fresh copper or purified to overcome any ununiformity of the chemical activity and/or any lack of smoothness of the entire surface of the shiny side. The evenness of the freshly formed copper surface enhances the homogeneity and completeness of the thermal oxidation-resistant plated layer to be formed subsequently by thermal oxidation resistance treatment, rendering it possible to take the full advantage of the thermal oxidation-resistant treated layer. Thus a surface treatment technique of imparting a thermal oxidation resistance upon heating at 300.degree. C. for 30 minutes to the shiny side of copper foil has now been successfully developed for the first time in the art.

Copper foil for printed circuits

A method is provided for producing high purity electrolytic copper useful, for example, to make a copper wire for use in sound or image reproducing systems, such as audio, video and television systems, etc. The copper wire consists of high purity copper in which silver and sulfur contents are both not more than 0.5 ppm and preferably has a crystal grain size not less than 0.02 mm and is unidirectionally solidified or is a single crystal. Such a copper wire is manufactured by continuously casting electrodeposited copper which has been obtained by refining by re-electrolysis of electrolytic copper, using a specially arranged casting apparatus having a mold projecting to an electrolytic bath.

Method for producing high purity electrolytic copper

The present invention relates to a copper wire for use in sound or image reproducing systems, such as audio, video and television systems, etc., and a method for manufacturing the same. The copper wire consists of high purity copper in which silver and sulfur contents are both not more than 0.5 ppm and preferably has a crystal grain size not less than 0.02 mm and is unidirectionally solidified or single crystallized. Such a copper wire is manufactured by continuously casting electrodeposited copper which has been obtained by refining by re-electrolysis of electrolytic copper, using a specially arranged casting apparatus having a mold projecting to an electrolytic bath.

Copper wires used for transmitting sounds or images

A method for preparing a raw board for use in printed circuits comprising the steps of first electroplating a foil or sheet of synthesized resins in an electrolytic bath containing copper sulfate, sulfuric acid, chlorine ion and a surface glazing agent including thiourea, and secondly electroplating the foil or sheet completed the above step in a conventional electrolytic bath containing copper sulfate and sulfuric acid. Also, an apparatus therefor is disclosed.

Growing community of inventors

Toda, Japan

Yoshio Kawasumi