Keith TeichmannSimilar to technology trends in other arenas, reduced size and weight, highly reliable materials, and greater functionality are in the forefront of connector design trends for the military market. Deployed in a variety of modern and “future soldier” applications, such as sophisticated command, control, communications, computer, and intelligence (C41) systems, connectors with these design considerations enable soldiers to become more mobile and their equipment to become more portable.

Defense applications have also always called for components that are highly reliable, as there is no room for field failure. Connector shells made of stainless steel material meet stringent requirements for corrosion resistance under MIL-Spec “P” grade standards, while at the same time meeting JEDEC standards for RoHS compliance. Still other connector designs are constructed with high temperature LCP dielectric materials, allowing them to be employed in applications with temperatures as high as 200°C – such as military vehicles as well as space and avionics use.

While materials such as stainless steel are highly reliable, they affect a connector’s weight. Soldiers often carry gear weighing in excess of 100 kilos, so components for soldier applications need to be extremely robust yet as lightweight and small as possible. These are often conflicting demands – robustness often requires the use of stainless steel as it is extremely durable and allows for a significant number of mating and unmating cycles; 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 but it is offset by the additional weight.

In terms of size, contact spacing as low as 0.635mm 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 0.193mm. Some nano-miniature connectors for soldier technology applications weigh no more than 25 grams, whereas other MIL-DTL-38999 connectors are up to 71% lighter and 52% smaller than comparable devices. 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.

Finally, because requirements in defense applications are both varied and stringent, connector functionality is also critical. As such, many high reliability connectors employ pogo pin/pad and breakaway technologies. The pogo pin/pad design utilizes an internal clip mechanism that maintains constant contact with the contact itself, reducing electrical resistance and accommodating misalignment issues. Further, the spring probe contact system and touch pads allow for ease-of-cleanability in the field where moisture and contaminants may be present, while breakaway designs incorporate a simple push/pull mating mechanism to mate and demate the connector system quickly as the need arises.