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Flex PCB Design Guide

The Sierra Circuits Flex PCB Design Guide helps you design highly flexible PCBs for electronics that move with you.

8 Chapters
8 Chapters

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.

The flex design guide helps you design flex and rigid-flex PCBs for all applications and covers:

  • Calculating the bend radius
  • Annular ring and via specifications
  • Build your flex stack-up
  • Controlled impedance for flex
  • Fabrication and drawing requirements


The advantages of flex PCBs

Ease of use

  1. Design constraints are minimal. PCBs can be designed to fit any device shape.
  2. Range of motion allows boards to suit nearly any application.
  3. Less mass reduces risk in environments with regular vibrations.
  4. Reduces errors found in standard assemblies.
  5. Reduces weight through the elimination of additional wires, cables and connectors.

Reducing PCB size

  1. Thinner and more lightweight than their rigid alternatives.
  2. Durable against motion and bending.
  3. HDI allows for the miniaturization of devices.

Rigid-flex PCBs

  1. Blends flexible and rigid PCBs. Commonly formed with flexible circuits connecting several rigid flex boards.

HDI for flex

  1. Smaller package size increases the need of HDI.
  2. Allows additional space for other features on the PCB.

Cost reduction

  1. Total cost of installation is reduced.
  2. Flex circuits eliminate several steps within the production process, shortening overall turntime and reducing cost.


Also inside this Flex PCB Design Guide:

  • The importance of the bend radius calculation
  • How to increase flexibility in ground
  • Manufacturing considerations for success
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Sierra Circuits PCB Certifications & Registrations

Sierra Circuits holds IPC-6012, IPC-6013, IPC-6015, IPC-6018, and IPC-A-600 PCB certifications
Sierra Circuits is ISO 9001:2015 certified for Military and Aerospace PCBs
Sierra Circuits is ISO 13485:2016 certified for Medical Device PCBs
Sierra Circuits is ITAR Registered
Sierra Circuits holds MIL-PRF-55110 & MIL-PRF-31032 PCB certifications
Sierra Circuits is certified by the National Institute of Standards and Technology
Sierra Circuits is REACH Compliant for PCB certifications
Sierra Circuits is RoHS Compliant for PCB certifications
Sierra Circuits holds PCB certifications for Flex, Rigid-Flex, and Rigid PCBs by the Underwriters Laboratory

Flex PCB design guidelines for manufacturing

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Sierra Circuits has been trusted by innovators as a go to resource for best in class circuit boards since 1986.

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About Sierra Circuits

Since 1986, Sierra Circuits has faithfully served more than 20,000 PCB designers and engineers with PCB design, manufacturing and assembly and High-Density Interconnect technology.

Sierra Circuits handles all aspects of PCB production. From PCB layout and design, to assembly and manufacturing—we provide our customers with unprecedented quality, reliability, and a single point of support.

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