Flexible PCB design specifications

Flexible PCB (Flexible Printed Circuit, FPC) is a bendable and flexible printed circuit board, which is widely used in consumer electronics, medical equipment, automotive electronics and other fields.

Since flexible PCB has excellent flexibility and bendability, it needs to follow a series of specifications and requirements during the design and manufacturing process.

The following will introduce the design specifications of flexible PCB in detail to help designers and manufacturers better understand and apply flexible circuit board technology.

Preparatory work before design

Flexible PCB design specifications
  1. Clarify design requirements and goals: Before starting the design, full communication should be carried out with the customer or project leader to clarify the application scenarios, performance parameters, size requirements, etc. of the flexible PCB to ensure that the design can meet actual needs.
  2. Determine material selection: Select appropriate flexible substrates, insulation materials, covering layers, etc. based on application needs and design requirements. Parameters such as the material’s flexibility, heat resistance, and electrical properties need to be considered.
  3. Understand the manufacturing process: Be familiar with the manufacturing process of flexible PCB, including circuit printing, etching, cutting, lamination, etc., so that the limitations and requirements of the manufacturing process can be taken into consideration in the design.

Detailed introduction to design specifications

  1. Minimum bending radius: In flexible PCB design, the minimum bending radius is an important parameter. It refers to the minimum radius at which a circuit board can be safely bent during the manufacturing process. If the bend radius is too small, it may cause cracks or damage to the circuit board during bending. Therefore, the bending properties of the material should be fully considered in the design and an appropriate bending radius should be selected. Generally speaking, the minimum bending radius is related to the thickness and bendability of the material, as well as the manufacturing process.
  2. Maximum line width and spacing: In flexible PCB design, the width and spacing of circuit lines are also important parameters. Thinner lines can provide higher connection density, but also increase the circuit’s resistance and reliability issues. Therefore, a compromise design needs to be made based on specific application requirements. Generally speaking, the maximum line width and spacing depend on the accuracy of the manufacturing process and the properties of the material.
  3. Substrate thickness: The substrate thickness of a flexible PCB will also affect its bendability and reliability. Thinner substrates can provide better bending, but will increase the stress on the circuit board when bending, which may lead to problems such as breakage. Therefore, the appropriate substrate thickness needs to be selected based on specific application requirements. In design, the impact of the thickness of the substrate on overall flexibility and reliability needs to be considered.
  4. Pad size: The pad is a metallized area used to connect the circuit board and other components. Its size and location need to be accurately determined to ensure reliable connection with other components. When designing, the appropriate pad size and spacing should be selected according to the connection requirements and the requirements of the welding process should be taken into consideration.
  5. Avoid sharp angles and right angles: In flexible PCB design, sharp angles and right angles should be avoided as much as possible. This reduces stress concentrations and increases board reliability and longevity. If sharp or right angles cannot be avoided, they should be chamfered. Right or acute angle areas can create stress concentrations that can cause cracks or damage to the board during bending or use. Therefore, arc transitions should be used as much as possible in the design to reduce the use of right angles and acute angles.
  6. Fixing method: The flexible circuit board needs to be fixed on the corresponding equipment in a certain way. The fixing method should be considered during design, such as screw fixing, welding, adhesive fixing, etc., to ensure the stability and reliability of the circuit board. Choose the appropriate fixing method according to the specific application scenario, and take into account the stability requirements of the circuit board in various environments.
  7. Thermal management: Since flexible circuit board materials have poor thermal conductivity, you need to consider how to effectively transfer heat out to avoid overheating problems. Factors such as thermal expansion coefficient and heat dissipation design should be taken into consideration in the design to reduce stress problems caused by temperature changes.
  8. Anti-electromagnetic interference: Electromagnetic interference may affect the performance and stability of flexible PCB. Therefore, appropriate measures need to be considered during design to reduce the impact of electromagnetic interference. For example, appropriate shielding materials, optimized wiring design, and decoupling capacitors can be used to reduce the impact of electromagnetic interference.
  9. Reliability design: Since flexible PCB is prone to problems such as fatigue damage and chemical corrosion during continuous bending, its reliability needs to be considered during design. Measures such as high-durability materials, adding reinforcement ribs, and optimizing circuit design can be used to improve the reliability of flexible PCBs.
  10. Repairability design: When designing a flexible PCB, its repairability also needs to be considered. Since the structure of the flexible circuit board is relatively complex and difficult to repair, it should be designed as modular as possible to facilitate repair and replacement of components.
  11. Environmental protection requirements: With the increasing emphasis on environmental protection issues, environmental protection requirements also need to be considered when designing flexible PCBs. Measures such as selecting environmentally friendly materials, optimizing material usage, and reducing unnecessary connections should be used to reduce its impact on the environment. At the same time, recyclable materials and processes should be used as much as possible to improve the environmental performance of flexible PCBs.

Design verification and testing

After the design is completed, verification and testing are required to ensure the feasibility and reliability of the design. The content of verification and testing can include the following aspects:

  1. Design Review: A careful review of the design to ensure it meets specification requirements and customer expectations. Check the design for completeness, feasibility and feasibility of the manufacturing process.
  2. Simulation analysis: Use simulation software to conduct stress analysis, thermal analysis, etc. on the flexible PCB to predict its performance and reliability under various working conditions.
  3. Sample production and testing: Make samples and conduct actual tests to verify the feasibility and reliability of the design. Test content includes electrical performance testing, mechanical performance testing, environmental adaptability testing, etc.
  4. Reliability test: Conduct accelerated life test, fatigue test and other reliability tests on flexible PCB to evaluate its performance and life under various conditions.
  5. Customer verification: Provide flexible PCB to customers for practical application verification, collect customer feedback and make improvements to solve problems.

Through the above verification and testing process, the reliability and performance of the flexible PCB design can be ensured, and a reliable basis can be provided for subsequent manufacturing and production.

Manufacturing and Processing

After the flexible PCB design is completed, it needs to be transformed into an actual product. Certain specifications and requirements need to be followed during the manufacturing and processing process to ensure that the flexible PCB produced meets the design requirements and quality standards. Precautions during manufacturing and processing include:

  1. Process flow management: Establish a complete process flow management system to ensure that each process link has clear operating procedures and quality standards.
  2. Material management: Conduct quality inspection and control on raw materials to ensure that the quality of raw materials meets design requirements.
  3. Equipment maintenance and management: Maintain and maintain manufacturing equipment regularly to ensure the stability and accuracy of the equipment.
  4. Quality inspection and control: Multi-level quality inspection and control are carried out during the manufacturing process to ensure that the quality of each link meets the requirements. Conduct comprehensive quality testing on finished products, including electrical performance testing, mechanical performance testing, etc., to ensure that the product is qualified.
  5. Environmental control: Keep the manufacturing environment clean and stable, and reduce the impact of environmental factors on product quality.
  6. Production safety: Comply with production safety regulations during the manufacturing process to ensure the personal safety and health of employees.
  7. Environmental protection measures: Take environmental protection measures to reduce waste and harmful substances generated during the manufacturing process and comply with environmental protection regulations.

Through the above measures, it can be ensured that the manufactured flexible PCB meets the design requirements and quality standards, and improves the reliability and performance of the product.

In short, the design and manufacturing of flexible PCB is a complex and delicate process that needs to follow a series of specifications and requirements. From pre-design preparation to manufacturing and processing, every link requires careful consideration and strict control.

By following design specifications, conducting verification and testing, and strengthening control of the manufacturing and processing processes, it is possible to ensure that the flexible PCB produced has excellent performance and reliability and meets the needs of various application scenarios.

At the same time, continuous technological innovation and improvement are also important driving forces for the development of the flexible PCB industry, promoting its wide application and recognition in more fields.

Flexible PCB manufacturer

Shenzhen Fumai Technology Co., Ltd. was established in 2007, focusing on one-stop services such as circuit board PCBA design and custom development, software programming, component procurement, SMT patching, DIP welding, assembly testing, and painting.

It has nearly 20 years of rich industry experience and complete production and testing equipment.

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