March 23, 2017

We have been mentioning the use of flex circuits in high speed applications over and over.


  • Flex circuits provides 5 times the density of high speed transmission cable
  • The use of RA copper allows high speed signals (see our technology discussion from last month’s newsletter “RA vs ED Copper”)
  • Flexibility. Flex allows thinner material stacks, bendability, flexibility and enables 3D solutions
  • Integration – Flex allows integration of connectors, PCB and cable all into one solution – cutting down on electrical resistance and at a minimized cost

Last month I had the CTO and Marketing Director of a connector company stop by our booth at the DesignCon exhibit in Santa Clara, CA. He explained that he was frustrated with the flex circuit industry. He was amazed at the lack of information available for high speed and impedance control flex and rigid flex.

After thinking about it for some time, I understand where he is coming from. If you make connectors and provide cable assemblies, you can guarantee results. Additionally, industry standards can dictate dimensions, signal counts, speeds, loss requirements, etc. Now, I am not trying to minimize the cost and testing that have gone into the connector and cable development. There is a ton of design and testing that goes into providing a connector, a cable and then a cable assembly that meets industry standards and customer expectations, and it is all well tested and documented.

light bulb on circuit backgroundFor flex circuits, we provide custom solutions every time. The solutions are complex. We deal with resistors, caps, semiconductors, ASICs, mechanical requirements, temperature, bend radius, material thicknesses, dielectric properties, trace and space widths, connectors – all affecting signal speeds. So it is difficult for PFC or any flex vendor to provide a simple answer to a high speed solution. Every one is different.

For example, we are in development on and shipping 5 different 28 gig/sec applications, for the same industry standard. Every build/construction is different – layer counts, material thickness components, bending requirements – while the one thing that is constant is the speed of the data output.

PFC and the flex industry, including all the material suppliers, spends millions of dollars searching and qualifying different combinations of materials, coverlays, and adhesives to create stack ups to meet all potential circuit requirements. To a certain extent, our database of information and test results becomes PFC’s Intellectual Property and in many cases is our competitive advantage.

The connector CTO and Marketing Director are good guys. We went through their specific requirement and provided a high speed solution to meet his customers’ needs. We look forward to working with them on a solution when their customer is ready.