Overcoming the Challenges with Rigid Flex Design

Mark Forbes
|  Created: May 22, 2017  |  Updated: December 2, 2020

wearables of the future

There is no question that wearable electronic devices qualify as “break-out products”. The market for wearables is forecasted to be $30 billion in 2016 and will grow to be $150 billion by 2026[1]. Most of these devices are simply impossible without rigid flex PCB design technology. This means that engineers and PCB designers need to become experts in designing, testing, and manufacturing in a wearable and “foldable” world.

The most familiar products are probably smartwatches that link with smartphones, and fitness trackers that are also worn on the wrist. But beyond these consumer products, wearables have made huge inroads into medical devices and military applications. Now, smart clothing is appearing that could virtually eliminate the possibility of incorporating rigid PCBs. So what is required to successfully design flex and rigid flex PCBs to keep up with the market?

Wearable Technology - What You’re Up Against

It goes without saying that a wearable device has to be small and virtually unnoticeable to the wearer. In the case of medical wearables, users usually don’t want them to be noticed by others either. Wearable devices that attach to the human body in one way or another dictates the flex circuitry and very dense layouts. Not only that, but rigid flex board shapes are often round, elliptical or even more unusual shapes. From a designer’s point of view these projects call for clever placement and routing. For such small and densely-packed boards, a PCB tool that is optimized for rigid flex designs makes handling odd shapes much easier.Rigid Flex

Typically, a rigid flex design has the electronic components mounted to the rigid flex PCB, then interconnected by flexible circuits. The flex circuit let the assembly to be bent to fit the assembly into the product enclosure.

The majority of PCBs designed today are basically rigid plates to connect circuitry. But, wearable devices present a number of difficulties for PCB designers that rigid flex PCB does not, including:

  • Precisely aligning flexible circuits and their respective components to fit their 3D packaging without putting stress on connection points.
  • Designing your stackup with both the rigid and the flexible of the assembly integrated - just as the final product will be.
  • Shaping the final assembly of rigid and a flexible printed circuit board to fit a product enclosure without producing stresses from bending the flex circuit.

On top of that, once the design is complete, there’s still the challenge of qualifying rigid flex fabricators, which can prove a bit more difficult than standard rigid PCB fabs. With all of these added challenges with rigid flex design, how can you ensure integrity while avoiding the issues not typically encountered in standard rigid board designs?

Master the Art of Rigid Flex PCB Design

Altium Designer® provides the most comprehensive set of tools for working with rigid flex designs. Stackups can be fully mapped and then modeled in 3D. Teardrops and reliability enhancement techniques are simple and quick. And, you can select either ODB++ or IPC-2581 for formatting your manufacturing output data to ensure complete design intent communications.

Rigid flex movie
PCB design software that provides 3D modelling lets designers see exactly how the PCB assembly fits together.

Want to learn more about overcoming the many challenges presented by rigid flex PCB designs with the powerful technology in Altium Designer? Download the free white paper Meeting the Challenges of Wearable Devices with Rigid- Flex PCB Design today.

About Author

About Author

Mark Forbes graduated from Bradley University with a BS in Electrical Engineering and has been in the EDA industry for over 30 years.

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