One circuit, multiple planes
A rigid-flex PCB combines rigid board sections and flexible dielectric regions in an integrated interconnect. It can replace selected board-to-board connectors and cable assemblies, allowing electronics to fit a three-dimensional enclosure. Whether this improves cost or reliability depends on the mechanical design, production yield, assembly process and service requirements.
Define the rigid and flex regions separately
Document total layer count, the conductive layers present in each region, flex thickness, copper type, coverlay, finished rigid thickness and the transition geometry. A six-layer rigid area does not automatically mean a six-layer flexible span. Use region-specific stackup drawings so the fabricator can review the intended construction.
Static installation or repeated motion?
A bend used during installation has a different fatigue requirement from a hinge that moves throughout product life. Specify bend direction, minimum installed radius, motion envelope, temperature and expected cycle profile. Do not select a bend radius from total board thickness alone; the flexible region and its full material stack determine the mechanical problem.
What to send for a useful review
Include Gerber or agreed intelligent manufacturing data, drill files, netlist, fabrication drawing, layer mapping, mechanical outline, bend diagram and quantity breaks. Identify impedance requirements, acceptance criteria, finish and revision. If the enclosure is still changing, attach a clearly marked preliminary drawing and list the dimensions that remain open.
Compare the full assembly
Compare the bare-board price with the cost of connectors, cable assembly, installation labor, assembly testing and field service. Integrated rigid-flex can reduce interconnect count, but a fabrication defect may affect the whole assembly. Use the same production quantity and acceptance criteria when comparing alternatives.