Two-layer flexible board, and the printed wiring board has a substrate a two-layer flexible substrate

摘要

PROBLEM TO BE SOLVED: To provide a double-layer flexible substrate by a metallization method superior in fine wiring line's processability in processing by use of a semi-additive method, and to provide a printed wiring board which uses, as a base material, the double-layer flexible substrate superior in fine wiring line's processability.;SOLUTION: A double-layer flexible substrate comprises: a base metal layer made of a nickel-containing alloy, and provided on at least one surface of an insulator film with no adhesive agent interposed therebetween; a copper thin-film layer formed on a surface of the base metal layer by a dry plating method; and a copper-plated film formed on a surface of the copper thin-film layer by an electric plating method. The content of sulfur included in the copper-plated film ranging to a depth of at least 0.4 μm along the direction from a surface of the copper-plated film to the insulator film is 10-150 mass ppm.;COPYRIGHT: (C)2014,JPO&INPIT