Flex PCB Assembly

What is Flex PCB assembly?

Flex PCB assembly is the process of fixing electronic components such as resistors, capacitors, and chips onto flexible materials such as polyimide using a welding process adapted to flexible substrates. After necessary surface treatment and performance testing, it forms a flexible, thin, and durable functional electronic component suitable for consumer electronics, automotive electronics, medical devices, and other scenarios.

The main tests for Flex PCB Assembly focus on electrical performance, mechanical reliability, soldering and appearance quality, and environmental adaptability, specifically including
1. Continuity test to check circuit continuity and troubleshoot open and short circuits: Verify the correctness of electrical connections. 
2. Insulation resistance test to verify the insulation performance between lines. 
3. Impedance test to ensure signal transmission quality. 
4. Withstand voltage test to prevent high voltage breakdown. 
5. Bending test simulating actual working conditions: Evaluate the circuit's ability to withstand repeated bending. 
6. Torsion test and tensile test to verify the solder strength of components. 
7. AOI inspection to identify defects such as cold solder joints and false solder joints. 
8. AXI inspection of the appearance and soldering quality of internal solder joints: Test the component's resistance to temperature fluctuations. 
9. And simulated high and low temperature tests and damp heat tests in extreme environments to comprehensively ensure the stable operation of components in complex scenarios.

Due to its thinness, flexibility, and bend resistance, Flex PCB Assembly is widely used in many industries with high requirements for space adaptability and miniaturization.

Consumer Electronics: Adapts to the irregular structures of foldable phones, smartwatches, wireless headphones, and other devices, enabling compact layouts. Used in cameras, game consoles, and other products, meeting the flexible connection requirements of complex internal circuits.
Automotive Electronics: Used in dashboards, central control screens, and in-vehicle entertainment systems, enabling flexible wiring between components. Adapts to the battery management system (BMS) of new energy vehicles, withstanding vibrations and temperature changes during vehicle operation.
Medical Devices: Used in implantable medical devices, possessing biocompatibility and resistance to the internal environment. Adapts to medical imaging equipment, enabling miniaturized, high-precision circuit integration.
Aerospace Industry: Adapts to drones, aviation sensors, and other equipment, reducing weight and adapting to vibration and shock conditions.
Industrial Electronics: Used in the joints of industrial robots, enabling reliable circuit connections between moving parts. Used in automated testing equipment and sensor modules, meeting the environmental resistance and flexible installation requirements of industrial scenarios.

For Kingfield's target audience, understanding the core differences between flexible and rigid PCB assembly is critical for product design, performance, and cost optimization. Below is a structured, industry-specific comparison to highlight key distinctions and guide decision-making:

1. Core Substrate Material

2. Mechanical Performance & Design Flexibility

4. Application Scenarios

5. Kingfield’s Assembly Capabilities Summary

Decision Guide for Customers Choose Flexible PCB Assembly if:
✅ Your product requires compactness, bendability, or 3D integration.
✅ You’re designing for wearables, automotive, aerospace, or IoT devices.
✅ Vibration/shock resistance is a critical requirement. Choose Rigid PCB Assembly if.
✅ Cost-effectiveness for high-volume production is a priority.
✅ Your product is stationary or requires large/heavy components.
✅ You need a simple, durable solution for standard electronics.

Kingfield offers end-to-end assembly services for both technologies, with engineering support to optimize your design for performance, cost, and manufacturability. Contact our technical team to discuss your specific project needs!

1.Preparation: Clean the flexible substrate, removing surface impurities and checking circuit integrity. Perform surface treatment on the substrate to improve soldering performance and prevent copper oxidation.
2.Component Placement: Use Surface Mount Technology to precisely position SMD components such as resistors, capacitors, and chips onto the designated locations on the substrate. Control pressure and temperature during placement to prevent deformation of the flexible substrate from affecting accuracy.
3.Soldering and Curing: Use reflow soldering to melt and cool the solder paste, achieving a stable connection between the components and the substrate. Some through-hole components require wave soldering to ensure soldering reliability.
4.Inspection and Troubleshooting: Visual Inspection: Use AOI equipment to check for defects such as cold solder joints, bridging, and component misalignment. Internal Inspection: Use X-rays to inspect the solder joint quality of BGA and other packaged components. Electrical Testing: Perform continuity and insulation resistance tests to eliminate short circuits and open circuits.
5.Post-Processing: Perform encapsulation and protection as needed to improve environmental resistance. Fold and shape according to the application scenario; some require layering and lamination. Finally, reliability tests such as bending and high/low temperature tests are conducted to ensure that the product meets the standards.