Definition

Rigid-flex PCBs combine rigid FR-4 sections with flexible polyimide circuits in a single integrated structure. The flex regions allow bending for packaging in tight enclosures, replace connectors and cables, and improve reliability by eliminating solder joints. Rigid-flex requires careful design of the transition zones between rigid and flex areas, with stiffeners and controlled bend radii. Construction can be bookbinder style (flex layers continuous through rigid) or loose-leaf style (flex attached at edges). Higher cost but enables form factors impossible with rigid boards and cable assemblies.