Building High-Frequency, High-Stability, and Highly Reliable Transmission Cables

 

Technical Challenges in High-Speed Cable Design

Driven by the exponential growth of data exchange demands in AI systems and cloud data centers, the performance standards for high-speed transmission cables are rising rapidly. Every aspect—from structural design and material selection to manufacturing precision and signal integrity (SI)—must now meet engineering tolerances in the millimeter or even micrometer range.

Emerging applications such as 112G PAM4 and PCIe Gen5/Gen6 are pushing the boundaries of frequency stability and long-term cable reliability, setting new benchmarks for performance.

 

Electromagnetic Spectrum

 

Signal Integrity (SI)

At high frequencies, signal loss and reflection become critical factors. To maintain signal integrity, conductors must be made from high-purity silver-plated copper. Insulation materials like FEP or foamed FEP are preferred for their low dielectric loss and thermal stability under long-term heat exposure.

 

Crosstalk Suppression and EMI Immunity

As data rates increase, controlling crosstalk and electromagnetic interference (EMI) becomes essential:

• NEXT/FEXT crosstalk should be kept below –30 dB.
• Multi-layer shielding and precise control of pair-to-pair spacing help minimize electromagnetic coupling.
• Metal foil shielding and optimized grounding structures are used to suppress radiation noise and improve overall EMC performance.

 

Structural Precision and Process Consistency

To ensure reliable high-speed performance, cables must be manufactured with ultra-high dimensional accuracy:

• Micron-level electrical tolerance control is necessary.
• Foamed dielectric layers and integrated tape wrapping reduce signal flaws caused by uneven winding.
• Advanced polymer processing during extrusion improves stability and reduces signal loss in wrapped sections.

 

While wrapped cable structures save valuable connector space, they must be precisely controlled to avoid SI issues, especially in ultra-wideband environments.

 

Durability and Reliability Testing Standards

High-end AI and server equipment demand cables that can operate reliably over extended periods:

• Jackets must meet VW-1 flame resistance ratings.
• Selected cables must pass "85/85" reliability tests (85°C / 85% RH), including JEDEC JESD22-A110 (BHAST) and JESD22-A101 (THB), to simulate prolonged exposure to high humidity and temperature.

 

Military-Grade Consistency and Traceability

For mission-critical and high-performance environments, cable uniformity and reliability must meet military-level standards. Modern manufacturing now relies on digital traceability systems—such as a single A4-sized record tracking 1,200 meters of cable—documenting dimensional variations (<3μm) and electrical deviations (<3pF).

This level of control ensures every production batch meets high process capability indices (CPK > 1.33), enabling full traceability and consistent product quality across the board.