COPPER ALLOY FOIL, FLEXIBLE PRINTED WIRING BOARD OBTAINED USING SAME, AND PROCESS FOR PRODUCING COPPER ALLOY FOIL

摘要

The zirconium content of the alloy composition of a copper alloy foil 10 of the present invention is 3.0 to 7.0 atomic percent, and the copper alloy foil 10 includes copper matrix phases 30 and composite phases 20 composed of copper-zirconium compound phases 22 and copper phases 21. As shown in Fig. 1 , the copper matrix phases 30 and the composite phases 20 form a matrix phase-composite phase layered structure and are arranged alternately parallel to a rolling direction as viewed in a cross-section perpendicular to the width direction. In addition, the copper-zirconium compound phases 22 and the copper phases 21 in the composite phases 20 form a composite phase inner layered structure and are arranged alternately parallel to the rolling direction at a phase pitch of 50 nm or less as viewed in the above cross-section. This double layered structure presumably makes the copper alloy foil 10 densely layered to provide a strengthening mechanism similar to multilayer reinforced composite materials.