US Patent 7545649 Double sided flexible printed circuit board

A flexible printed circuit board includes a flexible substrate having a first region, a second region and a third region; a first conductive foil layer disposed on a lower surface of the flexible substrate, so as to cover the first region, the second region and the third region; a first cap layer disposed on the first conductive foil layer; an second conductive foil layer disposed on an upper surface of the flexible substrate, so as to cover the first region, part of the second region, and the third region, and to expose part of the flexible substrate on the second region; and a second cap layer disposed on the second conductive foil layer.