flex cable with matched length & controlled impedance
Flex cable design requires different materials than rigid designs. Typical materials are a type of polyimide that have different dielectric constants than rigid materials. Like rigid boards, trace width, distance to the reference plane, and dielectric constant will determine trace impedance. Selecting the correct values will affect the flexibility of the cable. Material thickness & width along with amount of copper & weight will also contribute to the flexibility and bend radius of the design.