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Rigid Flex PCB Cost Optimization

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • Rigid flex PCBs combine the challenges of rigid board and flex PCB design.

  • The flexibility, small package size, and durability advantages of rigid-flex can be negated by the complexity, material, equipment specialities and lifecycle structural integrity challenges associated with rigid flex PCBs. 

  • OrCAD X includes functionalities and capabilities to help you overcome rigid flex PCB cost, design, and development challenges.  

Overlooking rigid flex cost factors can significantly impact your PCB development efficiency.
Rigid flex PC

Most circuit boards are rigid and green, but not all. In fact, many predictions indicate the range of application and usage of flexible PCBs will significantly increase in the near future and be a major contributor to future electronics innovation. Flex and rigid-flex PCBs offer a number of advantages; such as more varied installation possibilities, reliability and flexibility. However, leveraging these advantages is best achieved by knowing what issues influence rigid flex PCB cost and including these considerations during your design. 

Rigid Flex PCB Design Considerations

Flex circuit boards share many attributes with rigid PCBs. Consequently, all of the typical issues associated with designing rigid boards are also applicable for rigid flex PCBs. The converse is not true; however, and there are important design considerations and factors, as listed below, which have a profound impact on design and development, as well as rigid flex PCB cost.

RIGID FLEX PCB COST FACTORS

Design Consideration

Rigid-Flex Impact

Component Selection

Rigid-flex boards often will require additional components; such as stiffeners and/or bolts to aid in assembly or restrict movement once deployed.

Component Placement

It is highly recommended to only place SMD components on rigid surfaces, which may add constraints to your layout options.

Material Selection

PCB material must be chosen to allow for bend radius adherence and withstand thermal manufacturing requirements.

Trace Routes

When routing traces on flex boards, trace width and spacing should be maximized, without negatively affecting signal flow and integrity.

Stackup Configuration

The bendability required for rigid-flex PCBs is most easily achieved with minimal layer counts. 

Manufacturability

In addition to adding components to aid in assembly, excessive sequential laminations and heat requirements for fabrication should be kept to a minimum.

Standard Compliance

There are a number of PCB standards that specifically target flex boards. These include:


  • IPC 6013: Qualification and Performance Specification for Flexible/Rigid-Flexible Printed Boards

  • IPC 2223: Sectional Design Standard for Flexible/Rigid-Flexible Printed Boards

Operational Reliability

The high temperature exposure that circuits boards are exposed to during fabrication and assembly can have long term adverse effects. Therefore, process cycles should be minimized as much as possible by reducing layer counts that require lamination and choosing components such that multiple wave or reflex oven assembly stages are not necessary. 

Flexibility is the greatest advantage gained by opting for a rigid-flex board design. Yet, there are other characteristics that make flex boards attractive for engineers, as there are challenges that also must be considered. 

Benefits and Challenges of Rigid Flex PCBs

The major benefits of rigid flex boards are:

Rigid Flex PCB Benefits:

  • Flexibility

  • More condensed installation

  • Smaller package sizes

  • Less connectors and stress points for failure

  • Durability

Compelling attributes, which are often sufficient to warrant a rigid flex board design. Nevertheless, there are disadvantages as well. The most notable challenges to leveraging the advantages of flex and rigid flex PCB implementation are related to manufacturing.

Rigid Flex PCB Challenges:

  • Greater complexity

  • Additional components

  • More expensive board materials

  • More expensive manufacturing equipment

  • Maintaining structural integrity over product lifecycle

As shown, the benefits of opting for a rigid flex PCB design can be negated by higher design, manufacturing and operational–for boards that fail to maintain structural integrity over their lifecycle–rigid flex PCB costs, if design essentials are not implemented.

Efficient Flex Board Design Essentials

Knowing the challenges that must be overcome for rigid flex PCB design, manufacturing and usage may seem daunting. However, these issues can be successfully mitigated by following good rigid flex design rules and applying the best design tools. 

Guidelines for Rigid Flex PCB Design

  • Choose lightweight components
  • Use through-hole components, if possible
  • Choose high Tg materials
  • Follow your CM’s design for manufacturing (DFM) and design for assembly (DFA) rules
  • Use stiffeners and other mounting support to ensure reliable connectivity and operation

The PCB design software tools you employ are the key to not only implementing the best design rules, but in doing so the most efficiently. 

OrCAD X Reduces Time and Rigid Flex PCB Cost

In terms of development efficiency, designing your board to help facilitate the fabrication and assembly stages of manufacturing is among the most important actions you can take as a designer. Doing so ensures that your design specifications fall within the capabilities of your CM’s equipment and processes. This coupled with maximally reflecting your design intent are the drivers of manufacturing efficiency. 

PCB development optimization is achieved when manufacturing efficiency is coupled with design efficiency. The best way to design your rigid flex board efficiently is by applying advanced design software functionalities, such as the layout features inherent with OrCAD X.  

OrCAD X PCB Layout Features for Improved Rigid Flex Design

  • Enhanced 2D and 3D visualization to view board bend and flex region attributes
  • Intuitive design environment with OrCAD X Presto PCB Editor
  • Seamless schematic⇔PCB layout integration
  • Simple DFM/DFA import
  • In-design analyses to simulate and validate operation and performance before board build
  • Ability to define dedicated flex regions while specifying stackup properties.

Maximize the efficiency of your design and manufacturing processes by optimizing your board development to mitigate the rigid flex PCB cost challenges. Cadence, the industry leader in providing PCB Design and Analysis Software for engineers and teams for rigid, flex and rigid flex PCB design, has elevated the design environment with the OrCAD X platform.

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