Broadly speaking, a rigid flex PCB design will closely resemble a hardboard design, with the flexible layers fully extending into the rigid areas of the board. Similarly to hardboard layouts, a rigid flex PCB fabrication package will include Gerber layers, along with drill files, solder mask layers, nomenclature, perimeter/rout files, coverlayer, etc.
However, there are some key differences between the fabrication packages for rigid flex PCB’s and hardboard applications:
- A rigid flex PCB generally has many more dimensions on it, and should carefully define the requirements, as these boards are generally used in 3D applications. It should also accurately define the rigid to flex transition areas, as these are not always apparent when viewing the Gerber layers alone.
- The material layup in rigid flex boards is critical, and should be worked out in collaboration with fabricator. We can help you make the right choices in materials based your requirements such as UL flammability rating, minimum bend radii required, mechanical considerations, impedance control on both flex and rigid layers, RoHS certification, lead free assembly compatibility, and other considerations.
- Rigid flex PCB boards usually require additional layers in the Gerber files. Layers 1 and X will have solder mask layers, but you will also need artwork layers that define the coverlayer and bondply sections (if required) of the board, and how much each go into the hardboards. IPC 2223 recommends 0.100″ but fabricator may be able to accommodate less than that.
The IPC-2223 Sectional Design Standard for Flexible Printed Boards is an excellent resource for wise practices in both flexible circuit and rigid flex circuit design.