Applications for Flex Printed Circuit Boards

Posted on Sept. 12, 2017

Nearly all modern electronic products have benefitted from flexible and rigid-flex circuit technology. Today, electronic equipment typically uses flexible circuitry for applications that must process critical signals, need to perform flawlessly in extreme environments, enable national defense, manage heat and power distribution, reduce automobile accidents and more, and do so through increasingly miniaturized designs.

Advanced flexible circuit material options and customized flexible circuit design deliver unprecedented benefits to various sectors. For instance, anti-lock brake systems and engine maintenance units in vehicles are now increasingly replacing traditional wiring harnesses with polyimide-based circuits. Not only do these circuits save on weight and cost, but they can easily withstand under-the-hood environments as well. Other examples include:

  • Patients swallowing miniature cameras containing ultra-thin flex circuits, which allow physicians to see real-time gastrointestinal images, cutting down on time and diagnostic costs.
  • Oil and gas exploration thousands of feet below the earth’s surface relies on flexible circuitry for measuring and extracting process information.
  • Advances in flexible circuitry offer increased dynamic machine movement and step-changes of image resolution, while enabling critical rapid-scan analysis in MRI machines. With this, doctors can quickly diagnose a stroke and other critical health events at their early stages.
  • The next generation of satellites, ships, and military aircraft are now using rigid-flex PCBs with multiple layers and in-circuit patterns, with spacing as low as 0.001 inches.
  • 3-D antennas and advanced optical drivers use flexible PCBs in smartphones. These provide clear videos, while effectively dissipating heat.
  • Flexible circuitry has been spectacularly effective in reducing the weight of wiring harnesses in automotive wiring.

Although the concept of flexible circuitry is not new, as early researchers had patents issued in 1903, the defense and aerospace industry developments in the 1950s triggered the momentum of using flexible printed circuits as a replacement for wiring bundles. This led to a vast expansion of the use of flex PCBs across consumer and industrial electronic sectors. Beyond the 1990s, the growth of flex solutions took off with technical advancements, the demand for replacement of rigid boards, and the shrinking of wiring design footprints, including space constraints.

The market for flexible circuits opened further with the use of all-polyimide circuitry as the base for environments where temperatures exceeded 200°C, such as under the hood of an automobile. Even space exploration is making use of flex circuits with NASA using them in Mars explorations, where flexible circuitry components facilitated capturing panoramic views of the surface of Mars, and the search for water there.

Future Applications

Manufacturers are coming up with newer fabrication techniques for flex circuits for the next generation of design options. They are using liquid crystal polymer and other similar low-moisture-absorption/high-speed dielectrics along with ultra-thin copper conductors of thicknesses less than 5 microns.

Others are experimenting with non-copper metal traces such as cupro nickel or Inconel. These and other thermal management components on the flex circuits deliver precise heating. Such advances are improving navigation for pilots and other naval aviators, acting as deicers for aircraft wings. Flexible circuits heat up the wings quickly, shedding unwanted ice and preventing it from building up in flight, thereby improving airline safety.

Flexible circuits are also being increasingly used by hospitals for their newborn incubation chambers, surgical rooms, and equipment support, all of which require consistent and uniform temperature control. Additionally, flexible circuits are in great demand in low-power environments, such as in deep-space satellites for heating, in military electronics for vision systems, and in the automotive sector for heating and cooling of seats.

The requirement for flexible circuits is evolving very fast, as they are increasingly being used in electronic devices. They are allowing equipment to become efficient, rugged, and lightweight, improving development of miniature, complex, next-generation electronics.


The requirements for flexible circuits are evolving very fast, as they are increasingly being used in electronic devices. They are allowing equipment to become efficient, rugged, and lightweight, improving development of miniature, complex, next-generation electronics.

Copyright © 2019 Royal Flex Circuits