The copper weight and corresponding thickness used in a flexible circuit board need to be carefully selected in order to meet both the electrical and mechanical bend requirements of specific flex circuit design. Copper weight for a flex PCB is both the stiffest and most critical component.
Copper Flex PCB Weight Recommendations
It is recommended to use the thinnest and lowest copper weight in your flexible circuit design that meets the proper electrical requirements in order to improve the flexibility and reliability of the flex circuit.
Small Flexible Circuit Boards Used in a Medical Device
Base Copper
- 0.33 oz. - 0.00046" (0.012mm) ED Copper
- 0.5 oz. - 0.0007" (0.018mm) RA Copper
- 1 oz. - 0.0014" (0.036mm) RA Copper
- 2 oz. - 0.0028" (0.071mm) RA Copper
RA = Rolled Annealed
ED = Electro-Deposited
Most Common Copper Weights
The most common flex PCB copper weights are 0.5oz and 1oz, however, lighter copper weights are available. 2oz and greater copper weights are also available when manufacturing flexible PCBs but may not allow the required flexibility needed for the particular application that they will be used in. Using 2oz and greater copper weights in your flex circuit could create additional design and manufacturing challenges.
Summary
When designing a flexible printed circuit board, it is always the best practice to make sure your design meets current IPC standards with regard to specific flexible materials, circuit design, performance, and assembly processes involved in manufacturing flexible circuits.
Visit our website for more information on flexible PCB gerber layout & design recommendations.
Key Takeaways
- Copper weight is the most critical factor in flex PCB design: It directly impacts both electrical performance and the mechanical bend reliability of the circuit.
- Use the thinnest copper that meets electrical needs: Minimizing copper weight improves flexibility, reduces stress during bending, and increases long-term reliability.
- Standard copper weights vary by process: Common options include 0.33 oz ED copper, 0.5 oz RA copper, 1 oz RA copper, and 2 oz RA copper, with RA (rolled annealed) providing superior flexibility.
- 5 oz and 1 oz copper are most commonly used: These balance electrical performance with the flexibility needed for medical, consumer, and industrial flex applications.
- Heavier copper (2 oz or more) adds challenges: While available, thick copper reduces flexibility and can create manufacturing difficulties, making it suitable only for specific high-current designs.
