Flex PCB Design Guide

Learn Insider Tips From the Flexperts!

Flexible printed circuits are quickly becoming the preferred printed circuit board. Unlike other boards and interconnects, flex circuits are lightweight, easy to install, durable, compact, and—yes—flexible. The range of motion can include over 360 degrees, making it the perfect choice for nearly any situation. You can use flexible circuits in “bend to install” or dynamic applications, where the circuits are continuously in motion. Flexible circuits are also advantageous for design packages where space is a primary concern.



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10 Chapters
26 Pages
5,000+ Downloads


1. Why design a flex PCB?

    1.1 Flexible PCB advantages
    1.2 Preparing the board outline and thickness

2. Calculating the bend radius

    2.1 Designing bend areas
    2.2 Increasing flexibility in ground planes

3. Controlled impedance in flex PCB designs

    3.1 Routing flex traces

4. Annular rings in flex PCBs

    4.1 Pad design for outer layers

5. Vias in flex PCB designs

    5.1 Flex vias
    5.2 Rigid-flex vias
    5.3 Drill-to-copper

6. Fab drawing for flex

    6. 1 Rigid PCBs vs flex PCBs

7. From design to assembly

    7.1 Designing rigid-flex PCBs

    7.2 Assembling flex PCBs
    7.3 Stiffeners and tear guards

8. Flex PCB stack-ups

    8.1 One-layer flex stack-up
    8.2 Two-layer flex stack-up
    8.3 Multilayer flex stack-up
    8.4 Rigid-flex stack-ups

9. Drawing requirements

    9.1 What to include in flex drawing notes

10. More information on flex PCBs

    10.1 Flex PCB standards
    10.2 Manufacturing classes

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Sierra Circuits has been faithfully serving PCB designers and engineers since 1986, and has worked with over 20,000 customers since then. We specialize in PCB design, manufacturing and assembly and High-Density Interconnect technology. From PCB layout and design to assembly and manufacturing, Sierra Circuits handles all aspects of PCB production. We provide our customers with unprecedented quality, reliability, and a single point of support.



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