Patent ID: 7869164

Claim:
A flexible printed circuit board comprising: a conductive layer in the form of a circuit pattern; a sealing layer in which the conductive layer is encapsulated; and a metal layer to which the sealing layer is attached, wherein the flexible printed circuit board has a dynamic region made up of respective first portions of the conductive layer and the sealing layer but devoid of the metal layer, and static regions each made up of respective extensions of the first portions of the conductive layer and the sealing layer, and a respective portion of the metal layer, whereby the metal layer enhances the rigidity of the flexible printed circuit board at the static regions thereof and the dynamic region is more flexible than either of the static regions, wherein the metal layer has edges each of which delimits a boundary between the dynamic region and a respective one of the static regions, and each of said edges having a curvature to minimize stress concentrations at the boundaries between the dynamic region and each of the static regions, and wherein the conductive layer comprises a set of real traces through which electrical signals are transmitted by the flexible printed circuit board, and dummy traces disposed to the sides of the set of real traces, respectively, the dummy traces spanning the boundaries between the dynamic region and each of the static regions to prevent cracks from occurring at the boundaries.