A rigid-flex PCB combines rigid PCB sections and flexible circuits into one integrated interconnect. They eliminate the need for connectors and cables by allowing the board to bend and fold, enabling complex three-dimensional packaging and improved system reliability. Rigid-flex is widely used where space, weight, durability and reliability all matter at the same time.
Key features
Integrated rigid and flexible layers
- Rigid sections support component mounting.
- Flexible sections enable dynamic or static bending.
- Seamless electrical interconnection throughout the board.
Flexible polyimide materials
- High thermal stability.
- Excellent mechanical flexibility.
- Long flex life for dynamic applications.
Reduced interconnects
- Eliminates connectors, cables and a long list of solder joints.
- Improves electrical reliability and signal integrity.
3-D packaging
- Boards can fold, twist or bend to fit compact enclosures.
- Ideal for complex mechanical designs and tightly-packed products.
Advantages
Improved reliability
Reducing interconnections cuts connector failures, solder-joint fatigue and signal discontinuities.
Space and weight savings
- Replaces cables and connectors.
- Reduces overall system size and product weight.
- Enables compact, lightweight devices.
Enhanced electrical performance
- Shorter signal paths.
- Reduced impedance discontinuities.
- Better signal integrity for high-speed designs.
Simplified assembly
- Fewer parts and assembly steps.
- Lower risk of assembly errors.
- Improved manufacturing yield.
Construction and stackup
Rigid-flex PCBs are built using a layered construction that may include:
- Rigid FR-4 (or polyimide) layers for component mounting.
- Flexible polyimide layers for the bend regions.
- Adhesive or adhesiveless bonding systems.
- Copper layers optimized for flex reliability (rolled-annealed for dynamic flex).
- Coverlays or flexible solder mask in the bend areas.
Stackups are carefully designed to balance mechanical durability, electrical performance and manufacturability.
Manufacturing process
Rigid-flex requires specialized expertise and tight process control:
- Flexible circuit fabrication.
- Rigid core fabrication.
- Controlled lamination of rigid and flex layers together.
- Precision drilling — mechanical and laser.
- Plating and via formation.
- Fine-line imaging and etching.
- Coverlay and solder-mask application.
- Electrical testing and inspection.
Rigid-flex vs standard PCB + cables
| Feature | Rigid-Flex PCB | Standard PCB + cables |
|---|---|---|
| Interconnections | Integrated | Connectors and cables |
| Reliability | Very high | Moderate |
| Size / weight | Compact, light | Bulkier, heavier |
| Assembly steps | Fewer | More |
| Long-term cost | Lower (system level) | Higher (failure prone) |
Where rigid-flex shines
Aerospace and defense, medical devices, wearables, industrial robotics, and any compact product where cables and connectors would be the weakest link. Talk to us early — stackup symmetry, bend radius and copper choice are best decided before layout.
Need help on your build?
Talk to a Sunrise PCB engineer.