Rigid-flex boards suitable for various electronic devices

A flex-rigid PCB (printed circuit board) is a specialized type of circuit board that combines flexible circuitry with rigid sections into a single, integrated unit. This hybrid design allows it to bend or conform to complex shapes while providing structural support in critical areas, enhancing overall reliability and space efficiency.

1. Structure and Materials: It typically consists of flexible polyimide layers (for bending) bonded to rigid FR4 or similar substrates (for stability), interconnected through plated through-holes or vias.

2. Key Advantages: This configuration reduces the need for connectors and cables, minimizing failure points, improving signal integrity, and enabling compact designs in devices with moving parts or irregular layouts.

• Consumer Electronics: Integrated into folding smartphones (supporting screen flexibility and camera module connections), laptops (hinge area interconnections), smart wearables (smartwatches, fitness bands) and true wireless earbuds, catering to tight internal configurations and repeated bending requirements.
• Automotive Sector: Applied in in-car entertainment systems, advanced driver assistance systems (ADAS) sensors, instrument cluster displays and automotive LED lighting, enduring vehicle vibrations and wide temperature variations.
• Aerospace & Defense: Deployed in satellites, airborne avionics, unmanned aerial vehicles (UAVs) and military communication gear, cutting down on weight while maintaining reliable performance in extreme operating conditions.
• Medical Equipment: Utilized in portable health monitors, implantable medical devices (such as pacemakers), endoscopes and diagnostic instruments, satisfying the miniaturization needs and specialized installation demands related to biocompatibility.
• Industrial Machinery: Incorporated into industrial sensors, robotic joints, automated control systems and IoT edge devices, adapting to complex mechanical motions and harsh industrial environments.

1. Inner Layer Prep: Fabricate and etch the patterns for both the Flexible (polyimide) and Rigid (FR4) inner layers.
2. Lamination & Stacking: Stack the prepared rigid cores, flexible layers, and adhesive prepreg. A critical step is the application of heat and pressure to bond the layers, carefully leaving the designated flexible areas unbonded.
3. Drilling & Plating: Drill the entire integrated stack and use Plated Through Holes (PTH) to create electrical connections between all layers (rigid and flex).
4. Outer Layer Patterning: Pattern and etch the outermost copper layers.
5. Protection: Apply Solder Mask to rigid areas and Coverlay (flexible protective film) to the flexible areas.
6. Finishing & Test: Apply the final Surface Finish (e.g., ENIG) and perform Electrical Testing to ensure functionality before cutting the final board outline.