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

In modern electronic devices, the ultra-fine coaxial cable (Micro Coaxial Cable) has become the preferred choice for high-frequency and high-speed transmission scenarios due to its excellent signal transmission performance and high flexibility. It can be seen in 5G communication, USB4, Thunderbolt 3, eDP HBR3, and PCIe Gen3/Gen4 interfaces. The I-PEX connector, with its high density, miniaturization, and excellent electrical performance, has become the ideal partner for ultra-fine coaxial cables. This article will discuss how to achieve efficient and stable signal transmission from three aspects: cable characteristics, connector selection, and matching techniques.

Main Characteristics of Ultra-fine Coaxial Cable
Extremely thin coaxial cables are widely favored in the industry for their compact structure and excellent electrical performance, mainly featuring the following characteristics:
Small outer diameter design: The outer diameter is generally less than 1mm and can adapt to the assembly space of ultra-thin and lightweight equipment.
High flexibility and bendability: maintains 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: Adopted full-encapsulation shielding layer, effectively inhibiting 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.

Selection and Application Direction of I-PEX Connectors
I-PEX as a representative brand of high-density connectors, offers a variety of product series for extremely thin coaxial cables, including:
1. CABLINE® series
CABLINE®-VS II: 0.5mm spacing, horizontal insertion/extraction design, supports 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, supports 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, with transmission rates up to 16Gbps/lane.
2. FPL™ II series
FPL™ II: 0.5mm pitch, vertical insertion and removal, 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's bandwidth requirements.
Spacing and structural dimensions: evaluated based on the internal space of the whole machine.
Screening Design: For environments with high requirements for anti-interference, it should be prioritized to choose a full-screen structure.
The insertion and extraction method: Choose a vertical or horizontal insertion and extraction style based on the harness routing and assembly convenience.

Three, matching techniques for wiring harnesses and connectors
The correct matching method directly affects the stability of signal transmission and the lifespan of the product. The following points should be paid attention to in the design:
Specification compatibility: Confirm that the connector can support the cable's outer diameter, AWG specification, and impedance parameters.
Ensure consistent insertion and extraction direction: When wiring, ensure that 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.
Shielding and grounding reliability: Ensure good contact between the shielding layer and the earth wire, thereby enhancing 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 effects can be achieved in limited spaces, providing a solid support for the high-performance operation of modern electronic equipment.

I am[Suzhou Huichengyuan Electronic]Long-term focus on the design and customization of high-speed signal cable harnesses and ultra-fine coaxial cable harnesses, committed to providing customers with stable and reliable high-speed interconnection solutions. If you have related needs or wish to learn more about application solutions, please contact:Manager Zhang 18913228573 (WeChat number the same)。