Akitoshi Suzuki, Shin Fukuda, Kazuhiro Hoshino and Tadao Nakaoka, all from Imaichi, Japan, have developed a copper foil for a high-density ultra-fine printed wiring board.



An abstract of the invention, released by the U.S. Patent & Trademark Office, said: "The present invention is to provide an ultra-thin copper foil with a carrier which comprises a release layer, a diffusion preventive layer and a copper electroplating layer laminated in this order, or a diffusion preventive layer, a release layer and a copper electroplating layer laminated in this order on the surface of a carrier foil, wherein a surface of the copper electroplating layer is roughened; a copper-clad laminated board comprising the ultra-thin copper foil with a carrier being laminated on a resin substrate; a printed wiring board comprising the copper-clad laminated board on the ultra-thin copper foil of which is formed a wiring pattern; and a multi-layered printed wiring board which comprising a plural number of the above printed wiring board being laminated."