Page 45 - 2019 How-to-Specify E-Book
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Five Unique Characteristics of Micro-Coaxial Cable Assemblies
Nick Murata, Product Marketing, and Jack Ozeki, Field Application Engineer at I-PEX Connectors
Micro-coaxial cable assemblies are one of the best solutions for high-data-rate signal transmission applications. The unique characteristics of micro-coaxial cables and connectors combine to provide stable, high-reliability performance in high-data-rate signal applications, as long as the signal speed and transfer distance are considered during the specification process.
1. Micro-Coaxial Cables
High-data-rate signal transfer relies on a number of parameters, including impedance, insertion and return loss, and crosstalk. The center conductors, dielectric cores, and outer conductors of micro-coaxial cables are stabilized at a specific impedance and are suitable for matching. Matched and stabilized impedance creates a low return loss (or low reflection loss) and center conductors can secure enough cross-sectional area with flexible printed circuits and flexible flat cables (FPCs and FFCs) to achieve low insertion loss. In addition, the outer conductors of these cables have a shielding effect that helps reduce external noise and/or crosstalk between signal lines.
2. Micro-Coaxial Cable Conductors and Connectors
One unique feature of micro-coaxial cable is its outer conductor, which connects to the designated position using micro-coaxial connectors. In many cases, the outer conductor is ultimately connected to a ground on the PCB, so micro-coaxial connectors are designed to be compatible with grounding connections. These connectors also have separate contacts for the center cable conductor and the outer cable conductor, and the soldering part opens widely so that multiple micro-coaxial cables can be easily soldered to the contacts.
3. Shielded EMI Covers
Micro-coaxial connectors typically have exposed solder on the receptacle contact tails, so they almost always have a metal shielding cover that goes over the entire connector to prevent electromagnetic interference (EMI) and protect from electromagnetic susceptibility (EMS). The higher an application’s signal transfer data rates, the more critical it is to prevent EMI and EMS from the contact tails.

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