Cables and interconnects need to be able to withstand long life cycles, be able to operate in harsh conditions which can involve high levels of vibration, exposure to the elements and temperature extremes as well as cope with every day use in the field.
“Ruggedisation, along with reducing size, weight and power, remains a key differentiator in this space,” explains Phil McDavitt, Managing Director of Nicomatic. “Today, connectors and supporting cables are exposed to a wide variety of environmental conditions and have to operate over extended periods of time.”
There is also a growing need to shield sensitive electrical connections from electromagnetic interference (EMI) and pulse (EMP), as well as electrostatic discharge (ESD).
“We’re seeing more of this as the spectrum becomes more congested and contested,” says McDavitt, “especially at a time when electronic and information warfare are becoming more prevalent along with the push towards more drones and the growing use of robotic systems.
“We talk to customers and they are now asking about the shielding options that we can provide. Obviously, the specifications will be determined by the system under development but, in response to customer requests, we are now able to offer a scale of shielding to work with.”
Many military platforms under development also need to be able to transmit data such as high-resolution, multispectral imagery. As such connectors need to be able to support a broad range of different mission requirements. The military connector space is seeing growing demand for higher data rates, and companies are being steered by their customers to develop new high-bandwidth, radio-frequency (RF) and data connectors capable of functioning in the multi-gigahertz and multi-gigabit ranges.
Environmental concerns
When it comes to designing in a connector, the environment in which it will operate will always be of particularly importance.
“Where will the cable assembly be used? Will the conditions be sandy or corrosive? Does the connector need to be able to withstand high-vibration events and will it be mated and unmated frequently? All of these have to be taken into account when designing for military use,” McDavitt explains.
Connectors also have to be able to deliver when it comes to performance.
Are they going to be required to carry power and signal and what are the bandwidth requirements likely to be?
Connectors play a critical role in electrical and electronic systems; yet, interconnect requirements are frequently one of the last design issues to be taken into account and that often occurs at the end of the product design phase.
“If you look at the recent announcements at the Defence and Security Equipment International exhibition (DSEI) then it could be five years before we are engaged in developing and supplying the connectors and cables necessary for a particular project,” says McDavitt. “In terms of the UK, many of the projects under development are not about new innovative designs, much of that work is being out on the back-burner, rather it is about using existing technology at a time when defence budgets are under strain.”
Talking to a number of companies for this article it appears that the importance of good design is only ever really appreciated when the connectors used are either poorly manufactured or incorrectly specified.
“The quality and reliability of the connector is certainly critical and will directly influence the system’s performance and its reliability,” says McDavitt. “If connector selection is not given proper consideration, then the entire application can be left exposed to poor levels of performance and reliability issues.”
However, McDavitt doesn’t think that the approach and attitude towards connector design will change, any time soon.
“With these types of projects there will always be levels of discussion that will ultimately filter down to power supply and connector companies, like ourselves. It’s a well-defined process. However, it would help if we could get involved sooner and it would save a lot of time and avoid the risk of redesigns.”
The need to address reliability and quality was on display at the DSEI exhibition last month where a large number of connector companies were in attendance.
Lemo demonstrated its M Series High Power range which comprises of miniature high density ratchet-locking circular connectors that are suitable for use in harsh environments and are intended for applications such as soldier equipment, communications equipment and vehicles electronics.
Smiths Interconnect showed off the relaunched HBB series of single pole high power 300A and 500A circular connectors which have also been designed with extreme conditions in mind.
Above: Smiths Interconnect unveiled its relaunched HBB series of single pole high power connectors at DSEI 2019
Nicomatic took the opportunity to introduce its DLMM range of metallised composite 2mm pitch connectors, which can not only deal with extreme conditions but weigh in at less than 60% of its Micro D counterparts.
These connectors are available with 4-32 signal contacts, 1-8 high power or coax contacts, or a mixed arrangement of signal and high power/coax contacts in the same connector body.
“We have made these devices available in board-to-board, board-to-wire and wire-to-wire configurations for wire gauges of AWG 12-30 and in through-hole or surface-mount styles,” explains McDavitt.
The connectors on display were addressing key trends in the market from miniaturisation to lower weight and EMC protection.
“There’s a move towards using composite materials that are lighter, but just as tough as traditional materials – in many cases we can save between 20-40 percent in terms of weight and the modular approach we take means that you don’t have to go from one shell size to another. You have the flexibility to add up to 60 pins in one connector and that is a real benefit when it comes to prototyping. Designers appreciate that flexibility.”
Signal integrity
Another issue when it comes to cable and connector selection in the military space is the issue of signal integrity.
Today, connectors have to ensure that the signal that they receive is passed through it as purely and cleanly as possible and that is an increasing challenge as speeds go up and voltages decrease.
Providers of interconnect technologies are seeing greater demand for smaller connectors but with more complicated cable systems and a need to handle very fast and clean digital signals.
“Signal integrity in terms of the design and its management is now more important,” explains McDavitt.
“In the past there were rarely any specifications associated with this. You would supply a connector with a signal pin but there would be no specifications in terms of data.
“Today, newer connector releases have already been tested and qualified and because we have our own analysers in-house we can now test connectors should a customer ask us for something we haven’t got. That ability to provide a proper pass or fail test means that we can test connectors far more quickly.”
According to McDavitt companies, like Nicomatic, are looking to extend their testing capabilities.
“Testing in the past focused on electrical and mechanical testing, now we are having to extend those tests into the digital world and to some other areas such as higher power handling. How much current can a connector handle if it’s been specified for 3-5A but expected to handle 10A over a short period of time? We are helping customers to better understand the capabilities of connectors.”
The military market is evolving rapidly and the move to more mobile military systems is certainly a challenge as the demand grows to combine data with video and communications, leading to even more pressure in designing efficient and capable connectors.
