Famous High-Quality Rigid Flex PCB from China Factory - Single & Double-Sided, 4-16 Layer Suppliers Quotes, Factory
Product Description
What is Rigid Flex PCB?
Core Components & Structure
A typical rigid-flex PCB consists of three key parts, layered and bonded together through specialized processes:
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 between separate boards, reducing failure risks.
Key Advantages
Compared to standalone rigid PCBs or flex PCBs, rigid-flex PCBs offer distinct benefits:
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
Rigid-flex PCBs are indispensable in industries where space, reliability, and flexibility are paramount:
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).
Satellites, aircraft avionics, and military equipment (they withstand extreme temperatures, vibration, and space constraints).
In-vehicle infotainment systems, sensor modules, and advanced driver-assistance systems (ADAS) (adapt to the curved or confined spaces of car interiors).
Portable monitors, implantable devices (e.g., pacemakers), and diagnostic equipment (offer biocompatibility, miniaturization, and durability).
The Type of Rigid Flex PCB
The classification dimensions of Rigid-Flex PCB are numerous. The core classification can be based on structural form, flexible area characteristics, number of layers, and adaptability to application scenarios. Different categories correspond to different process difficulties and usage requirements.
This is the most commonly used classification method. The core basis is the connection mode and layout characteristics of the rigid and flexible areas.
The entire board has only one continuous flexible zone, with both ends or one end connected to the rigid board. Simple structure and low cost — the most common basic model in consumer electronics.
Contains two or more independent flexible zones forming complex structures through series connection of multiple rigid boards. Suitable for multi-directional bending and decentralized layout applications.
The flexible area achieves bending and twisting in 3D space, with rigid areas distributed in different spatial planes. Used in equipment with extremely compact, irregular shapes like UAV control boards.
The flexible area is only bent and shaped once during assembly, maintaining a fixed form during subsequent use and not subject to repeated deformation. Core requirement is structural stability after shaping.
The flexible area needs to withstand long-term and repeated bending, twisting and other dynamic actions. Requires extremely high fatigue resistance. Must meet the requirement of no failure after tens of thousands of bends.
Contains only one layer of conductive copper foil. Simplest structure and lowest cost. Suitable for low-complexity circuits such as simple toy control boards.
Two layers of conductive copper foil with interlayer conduction via vias. Widely used as peripheral modules for smartphones and tablets. Balances cost and practicality.
≥4 layers composed of alternating rigid-flexible-rigid layers. High integration for complex signal transmission. Suitable for satellite circuit boards and medical precision detection.
Uses PTFE-modified polyimide flexible substrates with low dielectric constant. Suitable for 5G equipment, radar systems, and satellite communication.
Made of high-temperature resistant materials (special PI), operating stably within -55°C to 200°C or wider. Used in aero engine peripherals and industrial high-temperature sensors.
Uses micro-vias and fine line width/spacing technologies for enhanced line density. Suitable for smartwatches and implantable medical devices such as pacemaker auxiliary boards.
How to Design Rigid Flex PCB
The design and production of rigid-flex PCBs need to take into account both the structural stability of rigid PCBs and the bending adaptability of flexible PCBs. During the design stage, potential risks in subsequent production and use should be avoided.
For dynamic bending scenarios, choose polyimide (PI) with good fatigue resistance. For static scenarios, polyester (PET) with lower cost can be selected. High-frequency equipment should use PTFE-modified PI substrates.
For flexible areas, rolled copper foil (with good ductility and bending resistance) is preferred. The surface of the flexible zone should be covered with a flexible PI film, with edges extending 0.2–0.3mm beyond the copper foil for protection and insulation.
Key Points of Manufacturing
The production of rigid-flexible combined PCBs integrates the processes of rigid and flexible PCBs, and requires additional control over the connection links between rigidity and flexibility.
Substrate cleaning: The surface of the flexible PI substrate is prone to adsorbing impurities. It is necessary to remove oil stains and oxide layers through plasma cleaning or chemical treatment to enhance the adhesion between the copper foil and the substrate. Rigid FR-4 substrates need to be dried and dehumidified to prevent air bubbles from forming during lamination.
Precise lamination: During lamination, temperature, pressure and time need to be controlled. The bonding parameters of the flexible zone and the rigid zone should be set differently. The stepwise lamination method is adopted — first the flexible layer is laminated, then it is laminated with the rigid layer to ensure a tight interlayer bond.
High-precision exposure: Flexible substrates are prone to stretching. Special fixtures should be used for fixation during exposure to prevent line deviation. UV parallel light exposure machines are adopted to ensure accuracy — line width error in the flexible zone should be controlled within ±0.02mm.
Etching process optimization: Alkaline etching solution is used to treat the copper foil in the flexible zone. The etching speed is slightly lower than that in the rigid zone to prevent excessive etching from causing line breakage. After etching, it is necessary to clean it in time to avoid residual liquid from corroding the substrate.
Flexible zone contour cutting: The flexible zone contour is processed by laser cutting (CO₂ laser or UV laser), with a smooth cut and no burrs, avoiding tearing of the base material caused by mechanical cutting. Laser power needs to be controlled to prevent damage to internal circuits.
Rigid zone forming: The rigid zone can be formed by CNC milling, with edges deburred and chamfered. The boundary between the rigid zone and the flexible zone needs to be ground a second time to ensure a smooth transition and reduce stress concentration during bending.
Surface treatment: Rigid areas can undergo surface treatments such as tin spraying, gold plating, and OSP to enhance soldering performance. The surface of the flexible zone is only protected by a covering film — high-temperature treatments such as tin spraying are prohibited to prevent deformation of the base material.
Full-process inspection: During production, interlayer adhesion (through peel test) and line conductivity (flying probe test) need to be inspected. Finished products need to undergo bending tests (dynamic bending requires simulating tens of thousands of cycles) and high/low temperature environment tests.
| Category | Parameter | Standard Capability | Advanced 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. | ||
