The Evolving Role of Interconnects in High-Frequency System Architectures

Read Below

• High-frequency interconnects now function as integral transmission structures that directly influence signal integrity, EMI performance and channel reliability.

• As bandwidths increase, connector selection must be evaluated through system-level metrics such as insertion loss, return loss, crosstalk and lifecycle stability rather than mechanical specifications alone.

• McKinsey Electronics supports engineering teams with access to high-performance interconnect technologies and engineering-led guidance focused on signal integrity, reliability and long-term lifecycle management.

In high-frequency electronic systems, the interconnect is no longer a passive mechanical interface. At multi-gigahertz data rates and microwave RF frequencies, connectors, cables, sockets, backplane interfaces and board-to-board transitions function as part of the transmission channel itself. Their electrical and mechanical characteristics directly influence signal integrity, EMI performance, channel loss and timing margin.

This shift is becoming more pronounced as interface standards continue to increase bandwidth. PCIe 7.0, released to members in June 2025, targets 128 GT/s signaling for AI infrastructure, cloud computing, 800G Ethernet, high-performance computing and related high-bandwidth systems. USB4 Version 2.0 defines operation up to 80 Gbps over certified 80 Gbps cables. These interfaces compress electrical margins and force engineers to treat interconnects as controlled-impedance channel elements rather than catalog-selected hardware.

Interconnects as Part of the Signal Channel

At lower frequencies, a connector can often be approximated as a low-resistance contact pair. That assumption fails when the physical dimensions of the interconnect become significant relative to signal wavelength or edge rate. The connector then introduces distributed inductance, capacitance, dielectric loss, conductor loss and impedance discontinuities. A high-frequency channel should therefore be viewed as a continuous electromagnetic structure.

The most critical transition is often not the connector body alone, but the launch region where the PCB trace, via field, connector pin, dielectric cavity and return-path geometry interact. Even when a connector is rated for high-frequency operation, a poor launch can become the dominant source of impedance discontinuity, significantly degrading return loss and create reflections that degrade eye opening or RF power transfer.

This reality is shifting engineering focus away from individual component specifications and toward complete channel behavior.

Why S-Parameters Are Driving Interconnect Selection

In modern systems, connector performance is increasingly evaluated through S-parameters rather than simple contact resistance.

Insertion loss describes how much transmitted signal is attenuated through the interconnect. Return loss describes how much energy is reflected because of impedance mismatch. Crosstalk describes unwanted coupling between adjacent signal paths.

Samtec notes that return loss, insertion loss, crosstalk and EMI all influence the suitability of high-speed interconnect solutions. Its high-speed connector rating methodology uses the -3 dB insertion-loss point as a practical bandwidth indicator.

This is why connector selection cannot be separated from channel simulation. Engineers must evaluate the connector, footprint, cable assembly, via structure and receiver equalization together. A connector that performs acceptably in isolation can fail in-system if the channel budget is already constrained by long traces, lossy PCB materials or dense routing.

As signaling rates continue increasing, channel margin is becoming a finite resource that must be managed across the entire signal path.

The Convergence of RF and High-Speed Digital Design

RF and high-speed digital systems historically used different design languages. RF engineers focused on impedance, VSWR, insertion loss, phase stability and shielding. Digital engineers focused on timing margin, eye diagrams, voltage levels and bit error rate.

At today's data rates, these disciplines increasingly overlap.

For RF and microwave connectors, minimizing VSWR and insertion loss remains central to preserving signal integrity. Molex describes its high-frequency RF connectors as targeting tight impedance and power-handling tolerances, with products reaching microwave and mmWave frequency ranges.

In high-speed digital systems, the same physics appears through different measurements.

A reflected RF signal becomes deterministic jitter.

Excessive insertion loss becomes inter-symbol interference.

Poor shielding becomes common-mode noise or radiated emissions.

The connector is therefore both an RF structure and a digital channel element.

Embedded EMI Filtering Changes the Interconnect Boundary

One important architectural trend is the integration of filtering into connector assemblies. EMI-filtered D-sub connectors and RF filter plates demonstrate how the interconnect can function as a boundary-level filtering element rather than a simple pass-through interface.

EMI filter plates utilizing feedthrough capacitors can suppress conducted interference at the module or bulkhead level, with attenuation increasing into the gigahertz range. This changes system partitioning.

Instead of placing the entire filtering burden on the PCB, engineers can move part of the EMI control function to the enclosure boundary. This can reduce board area, improve modularity and prevent high-frequency noise from entering or leaving a shielded compartment.

The trade-off is bandwidth.

Added capacitance can improve noise suppression but may introduce impedance discontinuities and increase insertion loss if not matched carefully to interface requirements. This makes filtered interconnects particularly valuable for power, control, lower-speed signal and selected RF isolation functions, while high-speed data paths require careful validation.

Materials and Contact Physics Still Matter at High Frequency

Although S-parameters dominate high-frequency evaluation, mechanical contact physics remains fundamental.

Industry connector design practices continue to emphasize the importance of contact geometry, normal force, plating stack and housing materials in maintaining long-term electrical performance. Gold-over-nickel plating is commonly used to reduce oxidation and stabilize contact resistance, while copper alloys such as beryllium copper support spring behavior and fatigue resistance.

At high frequency, this becomes increasingly important because current flows primarily near the conductor surface due to the skin affect.

Surface condition, plating wear, corrosion and micro-motion can alter the effective conduction path. In vibration-prone environments, small mechanical movements can modulate contact resistance and create intermittent impedance discontinuities.

Multi-point contact systems improve redundancy and stability, but they can also increase insertion force and wear if not properly engineered.

Reliability, Traceability and Lifecycle Implications

For McKinsey Electronics, the engineering challenge extends beyond selecting an interconnect that meets a published frequency specification.

High-frequency performance depends on how the connector interacts with the complete signal path, including PCB materials, launch geometry, cable assemblies, shielding strategies and environmental operating conditions.

As bandwidths continue increasing across AI infrastructure, communications systems, industrial platforms and advanced embedded designs, engineering teams increasingly require interconnect solutions that combine electrical performance with lifecycle stability, sourcing continuity and long-term reliability.

The key issue is not only whether a connector meets a frequency rating. The more important question is whether the interconnect remains electrically stable across production lots, mating cycles, environmental exposure and lifecycle requirements.

In aerospace, industrial automation, high-performance computing and communications infrastructure, interconnect failure often appears as intermittent field behavior rather than immediate hard failure. That makes traceability, qualified sourcing, revision control and lifecycle management critical engineering considerations.

A second-source connector with similar pin count and nominal impedance may not reproduce the same launch behavior, plating durability, shielding continuity or EMI profile.

For systems operating with increasingly narrow electrical margins, these differences can become significant.

High-frequency system design has moved the interconnect from the mechanical domain into the center of signal integrity engineering.

Connectors can significantly influence channel loss, reflection, crosstalk, EMI containment, jitter and long-term reliability. As interface bandwidths rise through PCIe 7.0-class and USB4 v2.0-class architectures, interconnect selection must be based on electromagnetic behavior, mechanical stability, material integrity and lifecycle control.

The engineering takeaway is direct: high-frequency interconnects should be specified as system-level transmission structures rather than commodity connection points. Their performance must be validated in the full channel, under realistic mechanical and environmental conditions, with traceability sufficient for long-term reliability management.

Selecting high-performance interconnects today involves far more than ensuring component availability. As data rates continue to increase, engineering teams must balance signal integrity, EMI performance, mechanical robustness, and long-term lifecycle considerations across the entire system. Dubai-Based McKinsey Electronics supports organizations throughout the Middle East, Türkiye and Africa by providing access to advanced connector, cable, and interconnect technologies, together with the engineering expertise needed to develop high-frequency systems that deliver consistent electrical performance from design through production and long-term field operation.