Famous High-Quality Rigid Flex PCB Manufacturers in China - 1 to 16 Layers Flexible Circuit Boards Supplier Factory Pricelist, Factory

Rigid Sections 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.

Flexible Sections 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.

Interconnect Layers 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 rigid and flex boards, reducing failure risks.

Single Flex Zone The entire board has only one continuous flexible zone, with both ends or one end connected to the rigid board. Used for "folding" or "turning" functions, such as flat cables connecting laptop screens to the main unit. Simple structure, low cost, most common in consumer electronics.

Multi Flex Zone Contains two or more independent flexible zones forming a complex structure through series connection of multiple rigid boards. Suitable for multi-directional bending and decentralized layout, such as industrial sensor modules and multi-camera mobile phone lens module circuit boards.

3D Rigid-Flex The flexible area achieves bending and twisting in three-dimensional space, with rigid areas distributed in different spatial planes. Used in UAV fuselage control boards and car instrument panel integrated circuit boards to maximize 3D space utilization.

Static The flexible area is only bent once during assembly, maintaining a fixed form during subsequent use. Core requirement is structural stability after shaping. Example: foldable phone frame connections.

Dynamic The flexible area withstands long-term repeated bending and twisting, requiring extremely high fatigue resistance and copper layer adhesion. Must meet no-failure requirements after tens of thousands of bends. Example: printer paper feed mechanisms, foldable wearable devices.

Single Layer Contains only one layer of conductive copper foil. Simplest structure, lowest cost, suitable for low-complexity circuits such as simple toy control boards and small remote controls.

Double Layer Two layers of conductive copper foil with interlayer conduction through vias. Widely used as peripheral modules for smartphones and tablet computers, balancing cost and practicality.

Multi Layer (≥4L) Composed of alternating "rigid layer – flexible layer – rigid layer" structures with power, ground, and signal layers. High integration for complex signal transmission and power management. Used in satellite circuit boards and medical precision detection mainboards.

High Frequency Uses low dielectric constant flexible substrates (e.g., PTFE-modified polyimide), reducing signal attenuation. Suitable for 5G equipment, radar systems, and satellite communication.

High Temperature Made of high-temperature resistant materials (special PI), operating stably from -55°C to 200°C or wider. Used in aero engine peripheral equipment and industrial high-temperature sensors.

HDI Uses micro-vias and fine line width/spacing technologies to enhance line density and reduce board size. Suitable for smartwatches and implantable medical devices such as pacemaker auxiliary circuit boards.

• Clear rigid/flex boundaries: A transition zone (usually 0.5–1mm) should be reserved at the boundary between the rigid zone and the flexible zone to prevent components, vias, and copper foils from crossing the boundary and to avoid cracking due to material differences during bending. Edges of the flexible zone need to be rounded (radius ≥1mm) to reduce stress concentration.

• Flexible zone 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 the outer copper foil is ≥15 times. Avoid overlapping and bending in the flexible zone to prevent long-term compression from damaging the circuit.

• Reasonable component layout: Heat-generating components (chips, resistors) should be concentrated in the rigid area and kept away from the flexible area. Heavy-duty components (interfaces, sensors) must be fixed in rigid areas with reserved heat dissipation space and fixing holes.

• Line direction: In the flexible zone, line direction is preferred to be horizontal (parallel to the bending direction) to reduce tensile/compressive damage to the copper foil. Minimum line width/spacing ≥0.1mm is recommended for flexible areas.

• Stacking structure: For multi-layer boards, the flexible layer should adopt a symmetrical structure to prevent warping. Rigid core materials are prohibited in the flexible zone; adhesive should be made of flexible materials such as acrylic.

• 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 flexible zone boundary. In high-frequency scenarios, "microstrip line" or "ribbon line" structures can optimize signal transmission.

• Flexible substrate: For dynamic bending, choose polyimide (PI) with good fatigue resistance. For static scenarios, polyester (PET) with lower cost can be selected. High-frequency equipment should use PI substrates with low dielectric constants (e.g., PTFE-modified PI).

• Copper foil and covering film: For flexible areas, rolled copper foil (with good ductility and bending resistance) is preferred. For rigid areas, electrolytic copper foil can be used. The flexible zone surface should be covered with a flexible PI film, with the edge extending 0.2–0.3mm beyond the copper foil for protection and insulation.

• Substrate cleaning: The surface of the flexible PI substrate is prone to adsorbing impurities. Remove oil stains and oxide layers through plasma cleaning or chemical treatment to enhance adhesion between the copper foil and the substrate. Rigid FR-4 substrates need to be dried and dehumidified to prevent air bubbles during lamination.

• Precise lamination: Temperature, pressure, and time need to be controlled during lamination. Bonding parameters of the flexible zone and 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. UV parallel light exposure machines are used to ensure line pattern accuracy, controlling line width error in the flexible zone within ±0.02mm.

• Etching process optimization: Alkaline etching solution is used for the flexible zone copper foil. Etching speed is slightly lower than in the rigid zone to prevent excessive etching causing line breakage. After etching, clean promptly to avoid residual liquid corroding the substrate.

• Flexible zone contour cutting: Processed by laser cutting (CO₂ or UV laser) with smooth cuts and no burrs, avoiding tearing of the base material from mechanical cutting. Laser power must be controlled to prevent damage to internal circuits.

• Rigid zone forming: Formed by CNC milling with edges deburred and chamfered. The boundary between rigid and flexible zones needs secondary grinding 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 flexible zone surface is only protected by a covering film. High-temperature treatments such as tin spraying are prohibited to prevent base material deformation.

• Full-process inspection: During production, interlayer adhesion (peel test) and line conductivity (flying probe test) need to be inspected. Finished products undergo bending tests (dynamic bending simulates tens of thousands of cycles) and high/low temperature environment tests to ensure stability and reliability.