| 摘要 |
PROBLEM TO BE SOLVED: To provide rolled copper foil for FPC having both excellent flexibility and appropriate softening characteristics by appropriately increasing the softening temperature of high flexibility rolled copper foil, and solving troubles to accompany its softening in the process of storage. SOLUTION: The rolled copper foil for a flexible printed circuit board having excellent flexibility and suitable softening characteristics has a composition containing 100 to 500 mass ppm oxygen, and containing one or more kinds selected from Ag, Au, Pd, Pt, Rh, Ir, Ru and Os in the ranges so as to control T defined by the following formula to 100 to 400: T=[Ag]+0.6[Au]+0.6[Pd]+0.4[Pt]+0.4[Rh]+0.3[Ir]+0.3[Ru]+0.3[Os] (wherein, [M] is the mass ppm concentration of the element M), and in which the total content of S, As, Sb, Bi, Se and Te is <=30 mass ppm. The rolled copper foil has a thickness of 5 to 50μm. The intensity (I) in the 200 plane obtained by X-ray diffraction for the rolled face after annealing at 200 deg.C for 30 min to the intensity (I0) in the 200 plane obtained by X-ray diffraction for the pulverized copper, i.e., I/I0 is >20. The rolled copper foil has a semi-softening temperature of 120 to 150 deg.C, and continuously maintains tensile strength of >=300 N/mm2 at a room temperature.
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