High-speed connectors are critical to the efficient and rapid transmission of data between components of a high-performance computing system (HPC). Applications such as scientific simulations, machine learning, big data analytics, and weather modeling frequently require large volumes of data to be rapidly transferred between storage, memory, and processing units. As data rates increase, issues such as signal degradation and insertion loss become more prevalent in high-speed connectors.
The term insertion loss refers to the reduction in signal power as the signal is transmitted through a connector, cable, or interconnect system (pin connections, for example). This results in signal attenuation, which can affect the quality of data transmission, especially at high frequencies. There are several reasons for the loss, including:
- Conductor resistance: The inherent resistance of connector materials.
- Dielectric losses: Signal energy lost in the dielectric material surrounding the conductors.
- Losses caused by reflection: mismatch between connectors and cables in terms of impedance.
- Losses caused by radiation: Energy that escapes the connector in the form of electromagnetic radiation, especially at higher frequencies.
As frequencies rise to 50-60 GHz, even slight imperfections in the connector’s design or material properties can have a significant impact on signal quality, as these signals are much more susceptible to reflection, crosstalk, and insertion loss.
The importance of grounding in high-speed connectors can be attributed to the fact that it contributes to the control of electromagnetic interference (EMI) and signal reflection, both of which contribute to insertion loss. Soft grounding materials are increasingly used to improve the electrical connection between the pin (or signal line) and the connector cage (the metallic shielding surrounding the connector). By improving the return path of current, minimizing impedance mismatches, and reducing EMI, these materials can reduce signal drop-off.
It is possible to position soft grounding materials in a manner that minimizes insertion loss, especially at higher frequencies, using several techniques.
A ground shield between pins and the connector cage is one method of improving signal grounding. Often, soft conductive materials are implemented, such as silver-based elastomers or conductive foams. At high frequencies, these shields ensure a reliable grounding path and help maintain impedance matching between the pin and connector cage.
This method has the advantage of reducing crosstalk between adjacent signal lines as well as providing a cleaner signal return path.
As connectors become smaller, and wire gauges used for pin connections become thinner, a challenge arises. To handle increasing workloads, HPC systems are designed to scale up by adding more nodes, processors, and memory. The high-speed connectors provide the necessary infrastructure to maintain performance, but the clusters used are more densely located to increase system bandwidth and reduce transmission distance and signal loss due to travel. Connectors and pin surfaces that are smaller require a reduction in the size of the soft grounding materials.
Engineering at Vanguard Products Corporation has developed a special line of grounding materials to address current challenges in the connector industry. Materials made from silicone sponges are difficult to manufacture and have a limited size range.
Vanguard’s team has developed materials as thin as 0.2mm-1.25mm with innovative tooling and material processing techniques that can compress up to 50% with minimal compression forces, while maintaining high conductivity (0.005 Ohm-cm or better) that provides grounding between the pins and the transmission wires. These materials are manufactured using silicone compounds, which are capable of withstanding temperatures up to 250 degrees Celsius in continuous processing.
The strips are attached with pressure-sensitive adhesives that do not affect the conductive path or profile of the strips. If the insertion loss is minimized and maintained at a level that is desired, the signal can be transmitted effectively.
You can find out more about these innovative materials on our website, www.vanguardproducts.com, or by contacting Vanguard Products Corporation at sales@vanguardproducts.com. Vanguard will also be exhibiting these new innovations at Electronica in Munich, Germany November 12-15, 2024, Hall B3, Booth 150 www.electronica.de.