TWO-LAYERED FLEXIBLE WIRING SUBSTRATE, FLEXIBLE WIRING BOARD, AND METHODS FOR PRODUCING SAME

摘要

[Problem] To provide a two-layered flexible wiring substrate and a flexible wiring board which are of excellent folding resistance, and methods for producing same. [Solution] A two-layered flexible wiring substrate of a multilayered structure in which an underlying metal layer composed of nickel alloy is provided to the surface of a polyimide film, with no intervening adhesive, and a copper layer is provided to the surface of the underlying metal layer, wherein the two-layered flexible wiring substrate is characterized in that the difference d[(200)/(111)] in the crystal orientation ratio [(200)/(111)] of the copper layer obtained before and after conducting the folding resistance test stipulated in JIS C-5016-1994 is 0.03 or greater.