What is the bend radius of a flex PCB?
Flex pcb bend radius refers to the minimum bending radius that a flexible circuit board can withstand during the bending process.
The bending radius of flex circuit board directly affects its service life and reliability. Generally speaking, the smaller the bending radius of flex circuit board, the shorter its service life and lower its reliability. Therefore, when designing flex circuit board, it is necessary to determine the bending radius of flex circuit board based on specific application scenarios and requirements.
In practical applications, the bending radius of flex circuit board also needs to be determined based on specific application scenarios. For example, in small electronic products such as mobile phones, the bending radius of flex circuit board is generally relatively small to adapt to the small size and bending needs of the product. In large electronic products, the bending half diameter of flex circuit board can be relatively large to ensure the reliability and service life of flex circuit board.
The bending radius of flex circuit board is one of the important parameters of flex circuit board, which needs to be determined based on specific application scenarios and requirements. When designing an flex circuit board, multiple factors need to be considered, such as the thickness, material, and line layout of the flex circuit board, to ensure that it will not break or be damaged during bending, thereby improving the reliability and service life of the flex circuit board.
When flex circuit board is bent, the types of stresses on both sides of the centerline are different. The inner side of the curved surface is pressure, and the outer side is tension. The magnitude of the stress applied is related to the thickness and bending radius of the flexible circuit board. Excessive stress can cause delamination of flex circuit board, copper foil breakage, and so on. Therefore, the lamination structure of flex circuit board should be reasonably arranged during design, so that the lamination at both ends of the bending surface centerline is as symmetrical as possible. At the same time, the minimum bending radius should be calculated based on different application scenarios.
How to calculate the optimal Flex pcb bend radius？
For Single Side FPC，Its minimum bending radius can be calculated by the following formula: R=(c/2) [(100 Eb)/Eb] - D, where R=minimum bending radius (in µ m), c=copper thickness (in µ m), D=coating film thickness (in µ m), and EB=allowable deformation of copper (in percentage). Different types of copper have different deformation amounts of copper.
A. The maximum deformation of the Rolled Anneal Copper Foil is ≤ 16%
B. The maximum deformation of the electrolytic copper is ≤ 11%.
Moreover, in different usage scenarios, the deformation value of the same material's copper sheet also varies. For one-time bending situations, use the limit value of the fracture critical state (for rolled copper, this value is 16%). For bending installation design, use the minimum deformation value specified in IPC-MF-150 (for rolled copper, this value is 10%). For dynamic flexible applications, the deformation amount of copper sheet is 0.3%. For magnetic head applications, the deformation of the copper sheet is 0.1%. By setting the allowable deformation of the copper sheet, the minimum radius of bending can be calculated.
Dynamic flexibility: The application scenario of this copper sheet is achieved through deformation. For example, the phosphor copper elastic piece inside the IC card holder is the part where the IC card contacts the chip after insertion. During the insertion process, the elastic piece continuously deforms, and this application scenario is flexible and dynamic.
For Double Sided FPC，Among them: R=minimum bending radius, unit µ m, c=copper sheet thickness, unit µ m, D=coating film thickness, unit µ m, EB=copper sheet deformation, measured as a percentage.The value of EB is the same as above.D=thickness of interlayer medium, in µ m。
SEEKPCB has extensive manufacturing experience in FPC and is proficient in the flex PCB prototype. For bending radius, we will calculate and optimize it for customers at the DFM level, so that the product can have better performance and lifespan.
If you have flex circuit prototyping demand, SEEKPCB will be your trusted solution.
