A flexible printed circuit board (150A-150H) has a flexible dynamic region (151), and relatively rigid static regions (152,153) between which the dynamic region (151) extends. Portions of a base layer (161), a conductive layer (165) extending on the base layer (161), and a cover layer (162) covering the conductive layer (165) make up the dynamic region (151). Extensions of the base layer (161), the conductive layer (165), and the cover layer (162), and portions of a metal layer (180) to which the base layer (161) is attached make up each of the static regions (152,153). The metal layer (180) enhances the rigidity of the flexible printed circuit board (150A-H) at the static regions (152,153). The metal layer (180) also has rounded corners (190A-D,192A-D) at sides of each of the boundaries (i,ii) between the dynamic region (151) and each of the static regions (152, 153) to minimize stress concentrations at the boundaries (i,ii). The conductive layer (165) is made up of real traces (166) through which electrical signals are transmitted, and dummy traces (167A). The dummy traces (167A) are disposed outwardly of the real traces (166) to prevent the flexible printed circuit board (150A-H) from cracking at the boundaries (i,ii) between the dynamic region (151) and each of the static regions (152,153). In a hard disk drive (HDD) the flexible printed circuit board (150A-F) electrically connects a head stack assembly (HSA) and a main circuit board.