Rigid-flex PCB Design Guidelines and Layout in Altium Designer
Military systems, foldable electronics, devices with odd form factor: if it curves, folds, or bends, then it probably includes a rigid-flex PCB. The right design software can help you create the layer stack you need to integrate a flexible ribbon into your PCB. With Altium Designer, you’ll have access to the tools you need to create any rigid-flex design you can imagine, examine its mechanical behavior, and prepare your board for production, and all within a single program.
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A unified PCB design package with the production and layout tools you need for rigid-flex PCB design.
At any given time, whether you are in your home, office, or automobile, you are likely surrounded by a dozen or more Printed Circuit Boards. Some of these PCBs are inevitably rigid-flex PCBs, especially in devices with curves, any electronic device that folds, and devices with electromechanical parts. From laptops to DVD players, rigid-flex PCBs have made their mark and will continue to remain important for years to come.
With devices becoming smaller and form factors bordering on downright strange, PCB designers should take the time to learn some important rigid-flex PCB design guidelines. Working with the right design tools can help you create any rigid-flex PCB you can imagine, as well as help you plan for manufacturing.
When you work with Altium Designer, you’ll have the capabilities you need to design your stackup for rigid-flex boards, layout electrical connections across your flexible ribbon, and prepare your boards for production. You’ll have full control over your component supply chain and you’ll be able to generate complete documentation within a single program. All this is possible thanks to Altium Designer’s underlying rules-driven design engine.
Rigid-flex PCB design begins with the right stackup. Because the flexible ribbon in a rigid-flex PCB is integrated into the interior layers of the rigid board, you’ll need to define a layer stack that places the flexible layers inside the rigid PCB layers. Although you can place the flexible ribbon near a surface layer in your Circuit Boards, mechanical durability will be maximized when you place the flexible ribbon in the central layers of your rigid boards.
If you like, you can extend a thick layer of copper across the flexible layer as ground and power planes. However, you can also route power lines across the flexible ribbon to provide power throughout your flexible regions. In this case, you should route return lines across the flexible ribbon alongside signal traces.
Advantages of Rigid-flex PCBs
Rigid-flex PCBs offer several advantages over their rigid counterparts. Perhaps most notably, these boards do not need connectors or cables to send electronic signals between boards. This prevents losses at the connector in the event of poor connections and eliminates problems with frequency compatibility. The final point is also important as rigid-flex PCB design naturally accommodates controlled impedance design. Finally, you can have some control over the stiffness of the flexible ribbon based on the amount of copper placed on the ribbon.
- Rigid-flex PCBs are unique systems, and some expert advice can ensure that your rigid-flex PCB ends up being manufacturable.Learn more about rigid-flex design from John Magyar.
- Like the foundation for a house, your rigid and rigid-flex PCBs won’t go anywhere without the right layer stackup.
- Powerful CAD tools in your PCB design software will allow you to define bending regions in mechanical drawings for your manufacturer.Learn more about defining bend areas in your PCB design software.
Unified hierarchical schematic and rigid-flex design in Altium Designer
Interior core/prepreg layers are typically made from polyamide and are clad with copper signal layers. The outer coverlay layers on the flexible ribbon are typically made from polyimide. The rigid portion of a rigid-flex board is normally FR4 as this easily accepts polyamide in the interior layers. You can then make connections from the rigid portion of the surface layer to the interior copper layers through vias.
Working and Designing with Rigid-Flex Materials
A rigid-flex circuit board is divided into zones that feature different materials and even different layer counts. You may need to transition from a rigid substrate to the flexible ribbon multiple times in a single system, and you will need to transition from the FR4 portion of the circuit board to polyimide and back as you move between these zones. In order to improve the structural strength of your flexible ribbon, it may be a good idea to add a stiffener. This also provides additional support for any components that are mounted on or embedded in the flexible ribbon.
- In addition to controlling the stiffness of the flexible ribbon by routing more copper, you can also use stiffeners to secure a board in an odd package.
- More advanced devices are pushing the limits of rigid-flex design and are forcing designers to pack more functionality on individual boards.
- Rigid-flex design is easiest when you use PCB design software with native 2D and 3D design tools.Learn more about designing using 2D and 3D design tools for rigid-flex PCB design.
Designing your board outline and bending region in Altium Designer
Rigid-flex design takes tools that let you define any board shape and bending regions in your board. As layer stacks vary between rigid and flex regions, you’ll also need to specify the stackup in each region. When your stackup and rigid-flex layout features are integrated alongside native 3D design features, you’ll have full control over all aspects of your board. You can also see exactly how your board will bend, allowing you to check mechanical clearances and design your packaging.
When these design features are accessible within a unified design environment on top of a rules-driven design engine, you’ll have the capabilities you need to create Printed Circuit Boards with flex circuits while staying within standard and custom design guidelines. Routing tools in this type of software are adaptable to rigid and flex circuits, allowing you to create a fully customized circuit board for any application.
Altium Designer: Unifying Rigid, Rigid-flex, and Flex Design
Altium Designer is the only PCB design package that includes tools that are specialized for rigid-flex design in a single program. These specialized tools are accessible within a 2D or 3D design interface. Best of all, these tools are integrated alongside traditional rigid PCB design features. No other design platform offers the same level of functionality and accessibility as Altium Designer.
- The unified environment in Altium Designer includes an extensive stackup library for multilayer PCBs, including rigid-flex PCBs.Learn more about the stackup materials library in Altium Designer.
- Rigid-flex PCBs are complicated enough on paper, but your PCB design software should make it easy to define layer stack regions in your board with 3D design tools and an intuitive layer stack manager.
- Routing through interior layers with blind and buried vias is just one measure for implementing physical layer security in military PCBs.See how you can design blind and buried vias in Altium Designer.
Altium wants you to be successful and will be there with the resources you need for success. You’ll have access to the AltiumLive forum, design tutorials from industry experts, webinars and podcasts, and an extensive knowledge base. While other PCB design software companies leave you to figure out design on your own, Altium gives you the resources you need to design successfully.
A unified PCB design package like Altium Designer includes all the tools you need for flex, rigid-flex, or rigid boards for any application. Instead of placing design tools in separate programs, Altium Designer includes all of your critical design features in a single program with a consistent interface and workflow. You can watch your productivity and quality skyrocket when you work with Altium Designer.