{"id":11352,"date":"2025-06-06T01:08:46","date_gmt":"2025-06-06T05:08:46","guid":{"rendered":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/?p=11352"},"modified":"2026-03-27T09:46:59","modified_gmt":"2026-03-27T13:46:59","slug":"bending-the-rules-how-to-design-smarter-with-rigid-flex-pcbs","status":"publish","type":"post","link":"https:\/\/blogs.sw.siemens.com\/electronic-systems-design\/2025\/06\/06\/bending-the-rules-how-to-design-smarter-with-rigid-flex-pcbs\/","title":{"rendered":"Bending the rules: How to design smarter with rigid-flex PCBs"},"content":{"rendered":"\n

In a season three of the Printed Circuit Podcast<\/em>, host Steph Chavez welcomed industry expert Tara Dunn<\/strong>, Director of Training and Education at SMTA, for a deep dive into the evolving world of rigid-flex PCB design. Dunn, whose career spans fabrication, supplier representation, and content creation\u2014including her long-running Flex007 column\u2014brought grounded insights into a technology many designers still consider \u201cblack magic.\u201d<\/p>\n\n\n\n

\u201cRigid-Flex is one of those technologies that feels familiar\u2014but it’s just different enough to trip people up,\u201d Dunn said. And when not approached intentionally, those trips can turn into costly falls.<\/p>\n\n\n\n

Dunn\u2019s unconventional entry into the industry\u2014starting in HR and accounting at a flex circuit manufacturer\u2014turned out to be a blessing. Early on, she was asked to work the production floor to better understand what she was budgeting for. \u201cI went through drilling, imaging, wet processing, final inspection\u2014the whole line,\u201d she recalled. \u201cThat foundation gave me more than just technical knowledge. It helped me speak the same language as fabricators.\u201d<\/p>\n\n\n\n

That language, she says, is what many designers still haven\u2019t learned.<\/p>\n\n\n\n

Chavez agreed, sharing that early in his career, flex design felt mysterious. \u201cIt was black magic,\u201d he said. \u201cPeople stuck with connectors rather than diving into the unknowns of rigid-flex.\u201d<\/p>\n\n\n\n

Why <\/strong>collaboration beats guesswork<\/strong><\/h2>\n\n\n\n

As designs get denser and systems shrink, the case for rigid-flex strengthens. But so does the need for upfront collaboration. From adhesive vs. adhesive-less polyimide to coverlay handling, Dunn emphasized that many manufacturing quirks are invisible from the CAD screen.<\/p>\n\n\n\n

\u201cYou\u2019re running ultra-thin materials through equipment built for rigid boards,\u201d she said. \u201cThat means taping leaderboards, managing scrap risk, avoiding key features near panel edges\u2014it\u2019s a completely different game.\u201d<\/p>\n\n\n\n

And then there\u2019s coverlay. \u201cMost people assume there\u2019s a photo-imageable version, like in rigid boards,\u201d she said. \u201cBut for higher copper weights or flex counts, you\u2019re drilling round holes over square pads. That\u2019s a specialized\u2014and delicate\u2014process.\u201d<\/p>\n\n\n\n

Chavez\u2019s advice? \u201cGet your butt on the fab floor. The things you\u2019ll learn by seeing it live will change how you design.\u201d<\/p>\n\n\n\n

When rigid-flex wins and what it costs<\/strong><\/h2>\n\n\n\n

\u201cThere\u2019s a tipping point,\u201d Dunn explained. \u201cIf space, weight, or performance is a concern, rigid-flex almost always wins. But people get hung up comparing raw fabrication costs.\u201d<\/p>\n\n\n\n

Instead of comparing just the board + connector price to the rigid-flex cost, she urges engineers to think holistically: multiple POs, higher assembly yield loss, longer cycle times, and supply chain complexity. \u201cWith rigid-flex, you issue one PO, inspect one item, and install one assembly,\u201d she said. \u201cThat\u2019s powerful.\u201d<\/p>\n\n\n\n

Rigid-flex in PCB also eliminates bulky connectors, a benefit familiar to Chavez from his aerospace background. \u201cI\u2019m holding a board in my hand where Rigid-Flex enabled a miniaturized system,\u201d he said. \u201cNo connectors. Less weight. Better thermal performance.\u201d<\/p>\n\n\n\n

The most common PCB design mistake? Dunn was blunt: \u201cDesigning a flex that doesn\u2019t flex.\u201d<\/p>\n\n\n\n

From improper bend radii to ignoring pad anchoring and stiffener needs, she\u2019s seen it all. \u201cDynamic vs. static flex makes a difference. And if you design flex like it\u2019s rigid, you\u2019re in for trouble.\u201d<\/p>\n\n\n\n

Chavez added that advanced 3D modeling helps, but nothing beats clear communication: \u201cShow your supplier the real-world application, the physical envelope, how the board bends, and where it connects.\u201d<\/p>\n\n\n\n

Learning the PCB <\/strong>rigid-flex way: the education curve<\/strong><\/h2>\n\n\n\n

Dunn\u2019s first piece of advice: Be intentional<\/strong>. \u201cThere\u2019s no shortage of resources,\u201d she said. \u201cSMTA, PCEA, IPC, webinars, eBooks, LinkedIn columns, podcasts. But make sure the source is trusted and vetted.\u201d<\/p>\n\n\n\n

She warns against relying too heavily on random YouTube videos or unverified blog posts. \u201cIf you\u2019re getting advice, make sure it\u2019s from someone who\u2019s actually built a board.\u201d<\/p>\n\n\n\n

Chavez echoed the sentiment. \u201cAuthors of these eBooks and columns are approachable. Add them to your network. Reach out. You\u2019ll be surprised who responds.\u201d<\/p>\n\n\n\n

Dunn also recommends using industry-vetted resources like Flex007<\/strong>, iConnect eBooks, and manufacturer websites from leaders like NCAB, TTM, and Sanmina.<\/strong><\/p>\n\n\n\n

Dunn closed with reassuring words for engineers just beginning their Rigid-Flex journey.<\/p>\n\n\n\n

\u201cEveryone is on a learning curve,\u201d she said. \u201cEven people with 30 years in the industry are now learning Ultra HDI, MSAP, additive processes. It\u2019s okay to make mistakes\u2014as long as you learn and keep iterating.\u201d<\/p>\n\n\n\n

Chavez nodded in agreement: \u201cRigid-flex isn\u2019t just about passing DRC. It\u2019s about passing HASS, HALT, and the shake-and-bake of real-world Mil-Aero environments. That\u2019s where design for manufacturability really<\/em> gets tested.\u201d<\/p>\n\n\n\n

Conclusion<\/strong><\/h2>\n\n\n\n

Rigid-flex PCB design may still feel like magic to some, but as Dunn and Chavez made clear, success lies in education, collaboration, and intention.<\/p>\n\n\n\n

From material stackups to supply chain planning, from coverlay cutouts to eliminating costly connectors, rigid-flex PCB design represents both a challenge and a competitive edge. The engineers who lean in, learn fast, and collaborate early will be the ones to unlock its full potential.<\/p>\n\n\n\n

Learn more expert advice on rigid-flex and flexible circuit design<\/a>, and listen to the Printed Circuit <\/em><\/strong>Podcast<\/em><\/strong><\/a>.<\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

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