Patent ID: 6915566

Claim:
A method of manufacturing a flex circuit on a flexible base polymer film including the steps of: a) superimposing on said film an embossing tool having raised areas comprising a pattern of conductors and vias corresponding to a circuit design, wherein, said raised areas are coated with a thin layer of metal, comprising copper, b) applying heat and pressure to simultaneously emboss the film and to transfer said thin metal layer from the embossing tool to the polymer film, c) removing the embossing tool, d) embossing a pattern corresponding to that of the second surface of a flex circuit, and simultaneously transferring a thin layer of metal into the embossed pattern, e) physically removing the embossing tool, f) plating a layer of copper to fill the vias and conductor patterns on both sides of the film, g) plating a layer of nickel and gold onto the exposed copper patterns, and h) applying a solder mask on the surface of the film surrounding the solder ball contact pads.