Abstract: Rigid flex printed circuit boards are formed with great efficiency and high yield in an assembly process wherein each circuit layer is punched in peripheral regions with alignment slots along two orthogonal radii and all layers are assembled without any acrylic bonding in a single hot press operation. A central flex layer spans a window defined in the rigid boards, and is covered with an insulating layer that overshoots the window and underlaps a rigid layer. At least the first rigid layer extends inwardly past the edge of the window, and provides a cantilevered edge support ribbon at the flex region boundary. Preferably the rigid and flex layers are all formed with a glass/epoxy material.