The copper thickness used in a flexible circuit board needs to be carefully selected

The copper thickness used in a flexible circuit board needs 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 Weight Recommendations
It is recommended to use the thinnest 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.

Flexible Circuits used in Medical Device
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 two most common flex PCB copper weights are ½oz and 1oz however thinner copper weights are available. 2oz and greater copper weights are also available when manufacturing flexible PCB's 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.

Conclusion
When designing a flexible printed circuit board, it is always the best practice to make sure your design meets current IPC standards in regards to specific flexible materials, circuit design, performance, and assembly processes involved in manufacturing flexible circuits.
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