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Connectors for Soldier Technology

Fri, 05/21/2010 - 12:12pm
Ted Worroll, David Impett, and Barry Cambeilh, ITT Interconnect Solutions

The “future” dismounted soldier sector is increasingly using advanced technology to equip its infantry, and sophisticated command, control, communications, computer and intelligence (C41) systems are being deployed that require increasingly sophisticated interconnection. Due to the nature of the applications, modern and “future” soldier use requires components that are miniature, lightweight, and capable of withstanding extreme environments.

Materials
Soldiers often carry in excess of 100 kilos (from gear such as night vision goggles, radios, navigation systems and firearms, to water and ammunition), so components for soldier applications need to be extremely robust yet as lightweight and small as possible. These are often conflicting demands, as robustness often requires the use of stainless steel as it is extremely durable and allows for a significant number of mating and unmating cycles (imperative given the number of times soldiers strip their gear on and off), however it’s not lightweight. Manganese is also an option in terms of robustness, but it is a more expensive material. Stainless steel is often implemented due to its robustness, however it is at the expense of a lighter weight material.

In addition to stainless steel, black zinc nickel is often utilized as a plating material because it is non-reflective, so the soldier isn’t spotted because of a shiny piece of metal. Aluminum shells and housings further contribute to a lightweight connector design.

Size and Sealing
In terms of size, contact spacing as low as 0.635 mm provides high signal density in minimal space, whereas other designs feature size 23 pin and socket contacts that have the equivalent electrical performance of size 22 contacts, reducing contact spacing to as little as 0.193 mm. Some nano-miniature connectors for soldier technology applications weigh no more than 25 g. The incorporation of knurled jackscrew assemblies also allows for easier mating and de-mating, which is critical in nano-miniature form factors. In some designs, the use of size 23 contacts for the interconnection of the cable also allows for the use of less stainless steel, thus decreasing both cost and weight. 

Trinity MKJ connectors from ITT Interconnect Solutions are 71% lighter and 52% smaller than comparable MIL-DTL-38999 circular connectors

Sealing
Sealing also plays a critical role, allowing the connectors to withstand harsh environmental elements often experienced during use in the battlefield. In addition to standard IP67 sealing, rear fluorosilicone wire seal grommets provide a strong environmental seal, while interface sealing can be achieved with a pin fluorosilicone interfacial seal. Several watertight connectors are also available with sealing to IP68, meaning the connectors are operational below 20 m of water, which is ideal for conditions where the soldier may be treading or submerged in water.

Contact System
Whether designed for thermal visors, navigation systems, fire arms, or even embedded electronics in carrying packs on the soldier where electronic circuitry or cabling is embedded into the soldier’s gear, key elements of connector contact systems designed into military applications include high reliability, resistance to shock and vibration, and quick disconnect capability.

Nano twist pin contact technology is gaining significant traction in connectors for soldier technology. Featuring five points of electrical contact and high-reliability crimp joints to ensure signal integrity and provide superior and reliable performance in harsh environments, including high shock and vibration conditions, nano twist pin contact systems allow the connector to perform much better electrically than comparable designs. Twist pin contact systems also provide increased flexibility in terms of wire gauge sizes suitable for back end harnessing, as well as special keys to prevent mismating during the ganging together of connectors. 

Nano miniature connectors employ a nano twist pin contact system, providing superior electrical performance in harsh shock and vibration environments

Quick disconnect is imperative for safety purposes. If a soldier is running and a cable gets caught on a branch, for example, they don’t want to be pulled backward or worse yet, strangled. The quick disconnect feature is often achieved through a canted spring and Pogo pin design, which allow for extremely high life cycles for the actual engagement and disengagement of the connector. A Pogo pin contact system uses an internal clip mechanism that stays in constant contact with the contact itself, helping to reduce electrical resistance while also accommodating misalignment issues.

The quick disconnect also provides ease of use for the soldier particularly as it relates to blind mating. If the soldier’s vision is impeded and he or she needs to feel for the metal receptacle, it will find home much more quickly and easily with the quick disconnect technology. Quick disconnect is also beneficial for a soldier when he or she needs to disconnect from a piece of equipment that is no longer needed, such as a battery pack for night vision goggles, tactical communications equipment, or a release mechanism on a telescopic weapon system.

The contact system also allows the connector receptacle to house individual touch pad contact areas, allowing for a highly effective electrical engagement point of contact. Further, the Pogo pin spring probe contact system and touch pads allow for ease of cleaning in the field, as the individual touch pad contacts incorporate no crevices for contaminants to accumulate.

Other features including audible tactile sound and touch are also being incorporated into some connector designs to let the soldier know the connector is fully mated and engaged, verifying reliability and signal integrity. Versatility is further increased through varying pin counts and different coupling mechanism options within a single connector, such as threaded and quick disconnect, as well as water tight, high mating, and super clean, for example. Because of high density and low contact resistance requirements, high pin counts with low contact pitch spacing and EMI shielding are also integral to connector designs for soldier technology.

Future Advancements
As soldier technology continues to advance, so too will the connectors used in these systems. Today, an increasing demand is for connectors that are sealed yet cleanable, meaning they meet at least IP67 standards but feature a system in which they can be instantly cleaned in the field if necessary. Some such solutions incorporate a pullback barrel system that facilitates cleaning and allows the user to return the connector to full operational functionality in seconds. 

These connectors shown above feature a pullback barrel system and can be cleaned more than 2500 times.


Further advancements are being considered that include bayonet-style coupling mechanisms with push-pull locking to lock the connector in place until the user pulls back on the coupling mechanism, guaranteeing no mismating; while others are designing-in a robust insert retention system to prevent the insert from pushing out from within the shell in the case of high-force mating environments. There are even some quick disconnect right-angle connectors being considered to provide soldiers with a quick connection solution off of the side of a firearm scope or on a radio.

Whether specified to equip infantry or for sophisticated command and control systems, miniature, lightweight connectors capable of withstanding extreme field use are being continuously designed into “future” soldier applications. As soldier technology advances, so too do the interconnect systems to include tighter tolerances, higher densities and smaller sizes for faster use, greater safety, and increased versatility.

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