Copper clad laminate and method for producing the same

A flexible circuit board comprising:

• a circuit of metal wires formed by a copper clad laminate on a low dielectric resin film, said copper clad laminate comprising a low dielectric resin film having a relative permittivity of 3.5 or lower and a dissipation factor of 0.0008 or lower at a frequency of 10 GHZ, and an electroless copper plating layer laminated on at least one surface of the low dielectric resin film, wherein a Ni content in the electroless copper plating layer is 0.01 to 1.2 wt %, and the electroless copper plating layer has a volume resistivity of 6.0 μΩ·cm or lower, wherein, assuming that a height of each metal wire from the low dielectric resin film is Hw, a width of a bottom base of the metal wire in contact with the low dielectric film is Lb, a width of an upper surface of the metal wire is Lt, and an inter-wire distance from another adjacent metal wire on the low dielectric resin film is S, at least some of the metal wires each have a conductor shape with a rectangularity A of 2.5 or greater, the rectangularity A being defined by a value (Hw/(Lb−Lt)) obtained by dividing the height of the metal wire by a difference between the width of the bottom base and the width of the upper surface, S of 60 μm or smaller, and a conductor wiring density WD of 10.0 or lower, the conductor wiring density WD being defined by a value (S/A) obtained by dividing the inter-wire distance by the rectangularity of the conductor shape.