How to Properly Match Ultra-Fine Coaxial Cables with I-PEX Connectors? Key Guide to High-Speed Transmission Stability

In modern electronic devices, micro coaxial cables, with their excellent signal transmission performance and high flexibility, have become the preferred wiring material for high-frequency and high-speed transmission scenarios. They can be seen in the 5G communication, USB4, Thunderbolt 3, eDP HBR3, as well as PCIe Gen3/Gen4 interfaces. The I-PEX connectors, with their high density, miniaturization, and excellent electrical performance, have become the ideal partner for micro coaxial cables. This article will discuss how to achieve efficient and stable signal transmission from three aspects: cable characteristics, connector selection, and matching techniques.

The main characteristics of ultra-fine coaxial cables
Extremely thin coaxial cables are widely favored in the industry due to their compact structure and excellent electrical performance, mainly featuring the following characteristics:
Small outer diameter design: The outer diameter is generally less than 1mm, which can adapt to the assembly space of ultra-thin and lightweight equipment.
High flexibility and bendability: still maintain good mechanical properties in complex wiring scenarios.
Excellent signal integrity: low insertion loss, low reflection, low VSWR (Voltage Standing Wave Ratio), ensuring stable transmission of high-speed signals.
Excellent electromagnetic shielding performance: Full encapsulation shielding layer, effectively suppresses external electromagnetic interference.
With these advantages, ultra-fine coaxial cables are widely used in laptops, smartphones, medical equipment, drones, and other high-performance miniaturized products.

Section 2: Selection and Application Direction of I-PEX Connectors
I-PEX is a representative brand of high-density connectors, providing a variety of product series for ultra-thin coaxial cables, including typical ones such as:
CABLINE® series
CABLINE®-VS II: 0.5mm spacing, horizontal insertion/extraction design, supporting transmission rates up to 32Gbps/lane, suitable for PCIe Gen5 and other high-speed applications.
CABLINE®-UM: 0.4mm spacing, vertical insertion and removal, using 360° full shielding design, supporting 20Gbps/lane speed, commonly used in Thunderbolt 3 and eDP HBR3 interfaces.
CABLINE®-UA II: 0.3mm spacing, smaller volume, suitable for module structures with extremely limited space, transmission rate up to 16Gbps/lane.
2. FPL™ II series
FPL™ II: 0.5mm pitch, vertical insertion/extraction, supports 12Gbps/lane speed, commonly used in high-speed signal channels such as USB 3.1.
When selecting a connector, the following aspects should be paid close attention to:
Transmission Rate: Select an appropriate model according to the system design bandwidth requirements.
Spacing and structural dimensions: assessed based on the internal space of the whole machine.
Shielding Design: For environments with high anti-interference requirements, the full shielding structure should be prioritized.
The insertion/extraction method: choose vertical or horizontal insertion/extraction style based on the cable harness routing and assembly convenience.

Section 3: Techniques for Harness and Connector Matching
The correct match directly affects the stability of signal transmission and the lifespan of the product. The following points should be paid attention to in design:
Specification compatibility: Confirm that the connector supports the cable's outer diameter, AWG specification, and impedance parameters.
Ensure consistent insertion and extraction direction: When wiring, make sure the connection direction is consistent with the harness routing to avoid performance degradation caused by bending stress.
Welding and assembly technology: control the welding temperature and time to prevent damage to the internal conductor or insulation layer.
Reliable Shielding and Grounding: Ensure good contact between the shielding layer and the ground wire to enhance the electromagnetic interference resistance performance.
In high-speed signal systems, the perfect match between extremely thin coaxial cables and I-PEX connectors is crucial for ensuring signal integrity and system reliability. Through reasonable selection and precise assembly, high bandwidth and low interference transmission can be achieved in limited spaces, providing solid support for the high-performance operation of modern electronic devices.

I am[Suzhou Huichengyuan Electronics], Long-term focus on the design and customization of high-speed signal cable harnesses and ultra-fine coaxial cable harnesses, committed to providing stable and reliable high-speed interconnect solutions. If you have any related needs or wish to learn more about application solutions, please contact:Manager Yin 18913280527 (WeChat same number)。