Custom Connectors are Common in High Performance Systems

By Jim Koch | September 17, 2024

The use of non-standard connectors is more common than most designers think. Many common connectors can be modified to achieve the performance, features, and format needed in high-performance systems.

Designers typically try to use standard interconnects in their end products. Most cite availability as to why they stick with standard, off-the-shelf products. However, there are times when a standard product does not exist that will meet the system’s design requirements, and a custom or modified interconnect is eventually selected.

The use of non-standard connectors is more common than most designers think. For example, approximately 25% of Samtec sales are non-standard products, ranging from slight modifications of existing products to completely new connector systems. These include high-speed board-to-board (mezzanine) systems, high-speed cable assemblies, backplane board and cable systems, two-piece pin and socket systems, active optical cable assemblies (called “mid-board optical transceivers,” in Samtec’s new Optics guide), and RF connector and cable assemblies.

Designers of high-speed systems (data rates of 112 Gb/s PAM4 per channel, with 224 just around the corner), like data centers, supercomputers, automated test equipment, and medical imaging, frequently use high-speed cable assemblies to transfer large volumes of data at high data rates.

Despite availability of a variety of standard high-speed cable assemblies, many customers specify modifications to these standard products. Common modifications include a custom PCB design for pin mapping specific to the application, placing protective sleeves around the low-skew twinax cable, or adding labels on the connectors and cables to identify the part number or provide instructions, to name a few of the hundreds of potential modifications that can be made.

Many designers modify high-speed cable assemblies to meet their system requirements.Above: Samtec’s AcceleRate® HP High Density Cable System

Another popular modification is mixing and matching the assembly’s end 1 and end 2 connectors. For example, a Flyover® QSFP-DD front panel connector may terminate to any number of high-density end 2 connectors placed adjacent to the chip. Designers request a variety of connector types for front panel, mid-board, and back panel interconnect systems.

Cutting-edge high-speed systems require next-gen high-performance connectors. However, many manufacturers’ designs are for more “straightforward” applications like industrial automation, robotics, embedded products, and vision and security systems. These boxes frequently use more basic, traditional interconnects like square post terminal (“header”) and socket strips. The relatively simpler design of these products – stripline plastic insulators, and centerlines that are not microminiature (for example, 2.54 or 2.00 mm vs. 1.00 or 0.80 mm pitch) – make for easy and relatively quick, and therefore inexpensive modifications.

Popular modifications include multiple-pin polarization – removing pins – to allow for keying, airflow, signal mapping, and additional space for power transfer or for creepage and clearance to meet safety and regulatory standards. Most designers who work with board-level connectors try to reach UL and CE 61800-5-1 specs that call out creepage and clearance distance given material grade, working voltage, and pollution degree.

Another popular modification is to add alignment and polarization features like shrouds, lead-ins, and blind mating support, as well as to combine power and signal pins into one connector. Combining power and signal pins into one connector system provides space savings on the PCB and improves tolerances for mating connector sets.

Most board-to-board connectors have well-designed signal to ground configurations for SI (signal integrity) performance, which require low mode-conversions to reduce radiated noise or susceptibility to noise. In the event additional shielding performance is needed, connectors can be encased in an outer metal shield, encircling the entire mated connector system to minimize the effects of EMI and EMC.

Plating is another common modification; this includes heavy gold, silver, and palladium nickel, to name a few. Most designers are aiming for higher cycles, protection against harsh environments, shock and vibration, and higher operating temperatures.

RF connectors and cable assemblies are frequently modified. Popular requests include ganged connectors on tighter centerlines or with odd pin counts. Designers often request our ganged RF connectors, such as MagnumRF™ or Bullseye® Test point system, with specific position counts, pitch, and custom layouts. This may allow them to reduce trace lengths or fit the connector into a limited space on their PCB, which permits the connector to be placed closer to the chip. Phase-matched cabling and labels are also common RF modifications.

Samtec RF connectors and cable assemblies are frequently modified.

All of the examples cited above are modifications to existing connectors. Some systems require completely new connectors that may include custom pins and stampings, plastic insulators and housings, custom RF, metals, special packaging, custom housings and footprints, to name a few. Work closely with your connector supplier to create an ideal interconnect solution to maximizes system performance.

Visit Samtec to learn more about solutions for high-performance design.