A flexible printed circuit board

PURPOSE:To enhance conductivity and to improve flexing resistance by forming a circuit pattern of rolled and annealed copper foil made of special copper alloy, and forming an electromagnetic wave shield layer, a jumper circuit, and a through-hole circuit of special conductive paint. CONSTITUTION:Copper alloy contains 0.02-3wt.% of at least one of Fe and Mg, 0.006-1wt.% of at least one of P and B, and 0.01-0.5wt.% of In, and the residue substantially of copper. Conductive paints (a), (b) include titanate-coated or zirconate-coated copper particles, resol type phenol resin, chelate layer forming agent, etc. The conductive paint (b) satisfies relationship between the phenol resin and infrared ray permeabilities of substituent groups. Further, thixotropic regulator is mixed. Electromagnetic wave shield layer 7 or/and a jumper circuit 6 are formed of the paint (a), and the circuit 6 and/or through- hole circuits 5a, 5b are formed of the paint (b).