Who is the preferred choice for high-speed signal transmission: ultra-fine coaxial cable束 VS FPC?

Under the current trend of electronic devices pursuing slimness and high performance, how to achieve high-speed and stable signal transmission in limited space has become an important challenge for design engineers. Although FPC (flexible printed circuit) is widely used, manufacturers in many high-end devices tend to choose ultra-thin coaxial cables. What is the reason that makes this micro cable stand out in the field of high-speed transmission?

Background of Application
With the popularity of new generation electronic products such as foldable smartphones, slim laptops, AR/VR devices, and so on, data transmission rates are continuously increasing, with rates above 10Gbps becoming the norm. In such high-speed environments, the industry usually adopts two internal connection solutions:
Firstly, it is FPC (Flexible Printed Circuit), which has the advantages of low cost and convenient wiring, but its anti-interference performance is limited in high-frequency environments.
The second is a super-fine coaxial cable束, which is specifically designed for high-speed signal channels and is often used for connections between the screen module and the mainboard. Many manufacturers eventually chose the latter, and the fundamental reason for this is that the super-fine coaxial cable performs better in terms of signal anti-interference and integrity control.

The anti-interference advantage of ultra-fine coaxial beam
Firstly, it has a full shielding structure. Each signal core wire is wrapped with an insulating layer and a metal braid layer, forming an independent shielding cavity, which is equivalent to putting a "protection armor" on each line. This design can effectively isolate external electromagnetic interference and prevent cross-interference between signals. In contrast, FPC relies solely on the surface coating film for protection and almost does not have real electromagnetic shielding capability.
Secondly, the impedance control of ultra-fine coaxial cable束 is more stable. In high-speed interfaces such as USB4, MIPI DSI, and eDP, impedance consistency directly determines signal integrity. By precisely controlling the spacing between the conductor and the shielding layer, ultra-fine coaxial cable束 can maintain the impedance within the range of 40~50Ω, thereby reducing the risk of reflections and jitter; in contrast, FPC is greatly affected by material and process errors during the manufacturing process, resulting in significant impedance fluctuations.
Again, it adapts to dynamic bending environments. The application scenarios of foldable screen hinges, notebook hinges, VR headsets, etc., are extremely compact, with the diameter of extremely thin coaxial cable bundles usually only 0.3mm~0.5mm, exhibiting excellent flexibility. Even after multiple bends, they can maintain excellent electrical performance. FPC is prone to cracks or performance degradation after frequent bending.
Finally, the data rate support is higher. Currently, high-end micro coaxial cables can easily support 10Gbps and even higher speeds, widely used in video and data interfaces, while FPC is prone to signal attenuation and crosstalk amplification in transmission exceeding 5Gbps.
Section 3: The Value and Limitations of FPC
FPC indeed still has advantages in the low-speed signal field—structurally thin, low cost, and free wiring, so it is still widely used in non-high-speed scenarios such as control signals and touch lines. However, in high-frequency and high-speed environments, its electromagnetic interference resistance and signal integrity are insufficient, which is also a key reason why high-end equipment generally shifts to extremely thin coaxial cables.

Extremely thin coaxial cable束 is not only a "thin" material, but also a systematic solution for high-speed signal transmission. It effectively compensates for the deficiency of FPC's anti-interference capability in high-speed transmission through independent shielding, precise impedance control, and high flexibility. In the future, with the continuous growth trend of high-speed interfaces and high-frequency signal applications, extremely thin coaxial cable束 will undoubtedly continue to become the mainstream solution for internal connections in electronic devices.
I amSuzhou Huichengyuan ElectronicsFocusing on the research and development, as well as customization, of high-speed signal cables and ultra-fine coaxial cables, committed to providing customers with stable and reliable high-speed interconnection solutions. If you have any related needs or wish to learn more about product details, please feel free to contact us:Manager Yin 18913280527 (WeChat same number)。