OEM High-Quality Rigid Flex PCB from China Suppliers | Custom 4-16 Layer Multi-Layer PCB Factory Manufacturer, Factories
Product Description
What is Rigid Flex PCB?
Core Components & Structure
Made of traditional rigid substrate materials (e.g., FR-4, a glass-reinforced epoxy resin). These parts provide mechanical stability to support electronic components (such as chips, resistors, capacitors) and ensure structural integrity.
Composed of flexible substrates (common materials include polyimide, PI, or polyester, PET). These parts are thin, lightweight, and can be repeatedly bent, folded, or twisted, allowing the board to adapt to irregular shapes or dynamic environments.
The rigid and flexible sections share internal conductive copper layers (signal traces, power lines, ground planes) that are seamlessly connected. This eliminates the need for wires, connectors, or solder joints, reducing failure risks.
Key Advantages
They can be folded to fit into tight, complex enclosures (e.g., foldable phones, wearables), reducing the overall size and weight of electronic devices.
Fewer connectors and solder joints mean fewer potential points of failure (e.g., loose connections from vibration or aging), which is critical for high-reliability applications like aerospace equipment.
Integrating multiple rigid and flex parts into one board streamlines the manufacturing process, reducing assembly time and human error.
Continuous copper traces minimize signal loss and electromagnetic interference (EMI), ensuring stable signal transmission—essential for high-frequency devices.
Common Applications
-
Consumer electronics:Foldable smartphones, smartwatches, laptops, cameras, and earbuds (e.g., the hinge area of foldable phones uses flexible sections to connect rigid display and battery boards).
-
Aerospace & defense:Satellites, aircraft avionics, and military equipment (they withstand extreme temperatures, vibration, and space constraints).
-
Automotive:In-vehicle infotainment systems, sensor modules, and advanced driver-assistance systems (ADAS) (adapt to the curved or confined spaces of car interiors).
-
Medical devices:Portable monitors, implantable devices (e.g., pacemakers), and diagnostic equipment (offer biocompatibility, miniaturization, and durability).
The Type of Rigid Flex PCB?
Classified by Structural Form
Single flexible zone rigid-flexible combined PCB: The entire board has only one continuous flexible zone, with both ends or one end connected to the rigid board. The flexible zone is mainly used to achieve "folding" or "turning" functions.
Multi-flexible zone rigid-flexible combined PCB: It contains two or more independent flexible zones and forms a complex structure through the series connection of multiple rigid boards.
Three-dimensional rigid and flexible combined PCB: The flexible area can achieve bending and twisting in three-dimensional space, while the rigid area is distributed in different spatial planes and seamlessly connected.
Classified by the Characteristics of Flexible Regions
Static rigid-flex combined PCB: The flexible area is only bent and shaped once during assembly, maintaining a fixed form during subsequent use and not subject to repeated deformation.
Dynamic rigid-flex PCB: The flexible area needs to withstand long-term and repeated bending, twisting and other dynamic actions, which requires extremely high fatigue resistance.
Classify by the Number of Line Layers
Single-layer rigid-flex PCB: Contains only one layer of conductive copper foil. It has the simplest structure and the lowest cost, suitable for low-complexity circuits.
Double-layer rigid-flexible combined PCB: Consists of two layers of conductive copper foil, with interlayer conduction achieved through vias. Widely used as a peripheral module for smart phones.
Multi-layer rigid-flex PCB: The number of layers is ≥4, usually composed of alternating superposition of "rigid layer - flexible layer - rigid layer", suitable for high-end electronic devices.
Classify by Special Function Adaptation
High-frequency rigid-flex combined PCB: Adopts flexible substrates with low dielectric constant and low loss, suitable for 5G equipment, radar systems, and satellite communication.
High-temperature resistant rigid-flex combined PCB: Made of high-temperature resistant materials (such as special PI), which can operate stably within a temperature range of -55 ℃ to 200℃.
High-density interconnect (HDI) rigid and flexible combined PCB: Uses micro-vias and fine line width and line spacing technologies to enhance line density and reduce board size.
How to Design Rigid Flex PCB?
Structural and Layout Design
• The boundary between the rigid zone and the flexible zone is clear: A transition zone (usually 0.5-1mm) should be reserved to prevent components, vias, and copper foils from crossing the boundary.
• Flexible zone location and bending planning: The bending radius should meet the requirement that "the minimum bending radius of the inner copper foil is ≥ 10 times the thickness of the flexible substrate, and that of the outer copper foil is ≥15 times".
• The layout of components is reasonable: Heat-generating components should be concentrated in the rigid area and far away from the flexible area.
Line and Layering Design
• The line direction is adapted to the bending direction: In the flexible zone, the line direction is preferred to be horizontal (parallel to the bending direction) to reduce the tensile/compressive damage.
• Stacking structure optimization: For multi-layer rigid-flexible combined PCBs, the flexible layer should adopt a symmetrical structure to prevent the board from warping.
• Via and grounding design: Metallized vias are prohibited in the flexible zone. All vias must remain in the rigid zone and be at least 1mm away from the boundary.
The Material Selection Meets the Requirements
• Flexible substrate: Choose polyimide (PI) with good fatigue resistance for dynamic bending; choose polyester (PET) with lower cost for static scenarios.
• Copper foil and covering film: Rolled copper foil is preferred for flexible areas. The surface of the flexible zone should be covered with a flexible covering film (PI film).
Key Points of Manufacturing
▶ Substrate Pretreatment and Lamination Process
• Substrate cleaning: Clean the flexible PI substrate surface through plasma cleaning or chemical treatment to enhance adhesion.
• Precise lamination: Control temperature, pressure, and time. Set different bonding parameters for the flexible and rigid zones to prevent deformation.
▶ Circuit Fabrication and Etching Control
• High-precision exposure: Use special fixtures for fixation during exposure to prevent line deviation. Control line width error in the flexible zone within ±0.02mm.
• Etching process optimization: Use alkaline etching solution for the flexible zone copper foil. The etching speed is slightly lower than that in the rigid zone.
▶ Cutting and Forming Processes
• Flexible zone contour cutting: Process the flexible zone contour by laser cutting (CO₂ or UV laser) to ensure a smooth cut with no burrs.
• Rigid zone forming: Form the rigid zone by CNC milling, and deburr and chamfer the edges.
▶ Post-processing and Quality Inspection
• Surface treatment: Rigid areas can undergo tin spraying, gold plating, and OSP. The flexible zone is protected only by a covering film.
• Full-process inspection: Inspect interlayer adhesion (peel test) and line conductivity (flying probe test). Finished products undergo bending and environmental tests.
| RIGID FLEXIBLE PCB CAPABILITY | |||||
|---|---|---|---|---|---|
| RIGID FLEX PCB | Flex layers | Lamination structure ≤ 4L; Book structure ≤ 10L | Lamination structure ≤ 4L; Book structure ≤ 12L | ||
| Max. Panel Size (shipping) | 210MM * 480MM | 460MM * 480MM | |||
| FPC dielectric thickness | 2MIL, 3MIL, 4MIL | 1MIL | |||
| PTH rigid-flex transition area | ≤ 1.2MM | ≤ 1.0MM | |||
| Pattern spacing, rigid area to rigid-flex transition area | ≥ 1.2MM | ≥ 0.9MM | |||
| Rigid-Flex Structure | Typical structure, Flying tail structure, Multi-flex book structure, Two-flex lamination structure, Single-sided asymmetric structure, Asymmetric structure etc. | ||||
