The more you align your designs with how these boards are built, the more successful your projects will be. This blog breaks down the rigid flex PCB manufacturing process so you can design smarter from the start.
Why Manufacturing Knowledge Matters
Every design decision you make has real-world consequences. Overlooking the smallest detail could result in delays, costly redesigns, or devastating failures in the field.
For example, something as simple as specifying the wrong bend radius or ignoring support during layer transitions can lead to cracking, delamination, or reduced flex life. The earlier you understand the trade-offs in the rigid flex manufacturing process, the better you can design for reliability, cost-efficiency, and long-term performance.
Deep Dive: The Rigid-Flex Manufacturing Process
The rigid flex manufacturing process involves multiple stages with unique design implications.
Material Selection & Constraints
Material choices define your board’s durability, flexibility, and thermal performance. Polyimide is the go-to for flex regions due to its heat resistance and mechanical strength. Rigid zones typically use FR-4 or polyimide. You’ll also need to consider how copper weight and adhesive systems affect impedance, bendability, and heat dissipation.
Know the trade-offs early. When choosing between coverlay and flexible solder mask, for example, coverlay offers better mechanical protection but is less precise. Flexible solder mask gives more accuracy for dense designs but may offer less durability.
Stack-Up Configuration
When planning your stack-up, you need to maintain controlled impedance across both rigid and flex zones. Pay close attention to layer transitions. Air gaps or stress points can form if they aren’t supported properly.
Use ground planes to control EMI and keep signal integrity high. Especially in mixed zones – small decisions here have big consequences later.
Drilling, Via Formation, and Plating
Flex layers are often drilled with lasers, while rigid zones may use mechanical drills. Each method comes with different tolerances and constraints. Vias must be designed for reliability, especially in dynamic environments. Follow IPC-2223 guidelines to avoid cracking or fatigue over time.
Plating gets more complex with high-layer counts or tight pitches. Missteps here can lead to poor connectivity or weak joints that won’t survive flexing.
Imaging, Etching, & Registration
It’s time to bring your design to life. Imaging tolerances limit how tight your traces and spacing can be, so you must use caution. Push them too far, and yield suffers.
Rigid-flex designs also require extremely tight registration. Any shift during imaging or etching can throw off pad alignment and compromise the entire board. Factor this into your DFM process.
Lamination & Bonding
Rigid-flex lamination is done in stages. Sequential lamination helps manage complex stack-ups but introduces new risks, like Z-axis expansion, resin squeeze-out, or layer misalignment.
Avoid placing critical features in transition zones. Use isolation routing and clear separation to reduce the risk of delamination during bonding.
Coverlay & Protective Layer Application
Coverlay acts as a flexible solder mask but behaves differently in production. It’s thicker and applied differently, so you must manage clearance and adhesive flow precisely. You also need to consider testing or reworks, especially if the application demands high-reliability.
Don’t assume one protective layer fits all. Each comes with electrical, thermal, and mechanical trade-offs.
Final Fabrication, Forming, and Testing
In the final stage, the board is routed, formed, and tested. For dynamic applications, bend regions require precision forming and stress relief techniques. Sharp bends or improper folding can kill flex-cycle life.
Testing is also more complex here. In-circuit testing for rigid-flex designs needs special fixtures and access planning. Design with this in mind from the start to avoid bottlenecks later.
For greater discussion, please see All Flex Solution’s Rigid Flex Design for Manufacturing Manual.
Manufacturing Constraints that Should Influence Your Design
Even the most well-intentioned designs can fail in production or the field if you ignore the rigid flex PCB manufacturing process limits.
- Respect bend radius rules. Too tight, and you’ll cause copper fractures or delamination. Stack materials with flex fatigue in mind. Thinner copper, staggered vias, and proper neutral axis placement can extend board life dramatically.
- Avoid placing copper in rigid-to-flex transition zones. These areas need relief. Use isolation routing or hatched copper patterns to reduce strain and improve flexibility.
- Know your limits. Every fab shop has minimum trace widths, via sizes, and aspect ratios they can hold. Design these margins into your layout, or you may face costly revisions later.
All Flex Solutions Is Your Rigid Flex Manufacturing Process Expert
The more you understand the rigid flex manufacturing process, the better you can design for performance, reliability, and cost.
Partnering with a manufacturer like All Flex gives you that edge. Our team works alongside you to streamline prototyping and bring your designs to life with precision.
Learn more about our rigid flex PCBs. For a more in-depth look at this information, please see All Flex Solution’s Rigid Flex Design for Manufacturing Manual.