Rigid-Flex printed circuit boards are boards that combine rigid and flexible board technologies in a single application. The flex layers are bonded to the rigid sections externally and/or between layers and the flexible substrate may be in a continual state of flex. 

Submitting a rigid-flex design is very similar to the standard PCB submission. Manufactures require that you enter in the thickness, number of layers, trace space, surface finish, copper weight, etc. for the rigid part and flex part individually.

Be sure to include a picture that clearly shows the location of the flex and rigid sections because it’s not always obvious to the CAM engineer. 

Below are some guidelines when designing and submitting a rigid flex PCB: 

• Avoid sharp corners and use soft curves when routing because sharp corners tear more easily when flexing. 

• Use teardrop shaped vias wherever possible

• Avoid mounting through hole components on a bend

• Use crosshatched planes when possible for the strongest bond between all layers

• Allow for product dimensional variations by making the flex region slightly longer than needed. 

• Consider the boards when they’re panelized and come up with the most efficient shape to reduce panel waste.

• Avoid sharp corners in the board outline and drill in the center to avoid tearing. Leave copper in the corner if you’re drilling in the corner for extra strength. 

• Widen the routes through the bending zone (this is especially important for permanent bends).

• Ideally, multi-layer circuits should have a bend ratio of at least 15:1. For double-sided circuits, the minimum ratio should be at least 10:1. For single-layer circuits, the minimum ratio should also be at least 5:1. For a dynamic application, aim for a bend ratio of 20-40:1.

• Rolled annealed copper is more ductile; plated copper is not the best choice for flexible regions.

• Specify if there are any additional stiffeners or adhesive backing requirements