Improving Flex Life in Rigid-Flex PCBs: Material & Structural Optimization
As rigid-flex PCBs become more common in automotive, medical, aerospace, and wearable electronics, mechanical reliability is becoming just as important as electrical performance. Repeated bending can lead to copper fatigue, cracked vias, or delamination if the design is not optimized.
Key engineering considerations:
• Select suitable materials. For dynamic flex applications, polyimide with high flexibility and rolled annealed (RA) copper generally provides better fatigue performance than standard ED copper.
• Design smooth rigid-to-flex transitions. Large corner radii and gradual copper transitions help reduce stress concentration.
• Optimize copper thickness. Thinner copper improves bending endurance while still meeting electrical requirements.
• Protect the bend area. Avoid placing vias, pads, or components within the bending zone whenever possible.
• Use a balanced stackup. Symmetrical constructions help keep the neutral axis centered, reducing strain during repeated flexing.
Rigid-flex reliability is rarely determined by a single factor. It results from the combination of material selection, stackup design, copper routing, and mechanical structure, all considered early in the design process.
What design practices have you found most effective for improving rigid-flex reliability?

Originally published on ShinePCB’s LinkedIn company page: 2026-07-21.