INTERCONNECTION By Robert Webber, product specialist, Powell Electronics I
f you drill right down, industry demands can be stripped back to some bare requirements. Smaller size, lighter weight, higher performance (which can mean higher power), lower cost. There is a nice industry acronym that covers this – SwaP-C (size, weight and Power – Cost) – and it applies perfectly to the selection of high reliability connectors.
Interconnect is an interesting subject because connectors are required to play a dual function. They must ensure the transference of electrical signals and sometimes power from one part mechanical function, physically joining cables and boards. Sometimes they also play a structural role. Ensuring signal integrity and/ or power continuity in high-reliability (hi-rel) applications such as defence or space, where extremes of shock, vibration and temperature consideration of the connectors used. Let’s take, for example, the CubeSat. CubeSats are a class of miniature satellite based around a cubic form factor where each side measures 10 cm (roughly the size of a milk carton), and weigh no .more than 2 kg. CubeSats have been deployed from the International Space Station, or launched as secondary payloads. Currently, several thousand CubeSats have been launched.
Obviously size and weight are of paramount importance. But since the concept of the CubeSat was to get into space at low cost - with launch costs ranging from $60,000-100,000 and construction starting at just $50,000 – component cost needs to by minimized. If we look at the consumer electronics industry – for example cameras and other portable personal examples of miniature, lightweight connectors that are very cheap. But for an aerospace or
SWaP-C – the new way to consider hi-rel connectors
space applications such connectors would not be able to withstand the levels of shock and vibration present at launch. A paper by Dave Pignatelli of the California Polytechnic State University, San Luis Obispo, entitled ‘Improving Launch Vibration Environments for CubeSats’ explains that the ‘actual levels (of shock and vibration) experienced by a CubeSat will vary due to a number of factors: but ‘internally isolated CubeSat levels ranged
from 3.7 Grms to 4.4 Grms’. Other applications there is the issue of temperature change. CubeSat experiences very high or sub-zero temperatures, as it passes from direct sunlight to - borrowing from Pink Floyd – the dark side of the moon.
Clearly another interconnection option is required, and many times, the preferred option is a commercial off-the-shelf (COTS) device, which meet the performance requirements set out by organisations such as NASA or the military, but which may not have been fully are often orders of magnitude cheaper than withstand the severe demands of the rugged environments they will be used in.
There is another issue to consider. Connectors that carry full NASA approval may well have been designed 30 to 40 years ago.
12 APRIL 2023 | ELECTRONICS TODAY
If you are operating in the commercial space market, a connector that was designed in the 1980s may not be the best component for your application in terms of size, weight, performance and cost (SWaP-C). Also, you may need to be able to source your parts for prototype designs from a distributor (such as Powell), which can supply sample quantities from stock. Hi-rel connector makers such as Harwin regularly have conversations with companies in the commercial space sector, which are desperately trying to move away from NASA and ESA standards, wherever they possibly can, exactly for this reason and because older connectors with various ‘hi-rel’ was suitable for the Voyager 2 spacecraft to investigate Neptune 40 years ago may well not be suitable for putting up a constellation of 300 low orbit communication satellites to deliver broadband to Africa. It’s a totally different challenge.
So it becomes obvious that we need a modern interconnect solution that has the environmental capabilities (shock, vibration, temperature) of Mil-Spec devices but with the more recent design. Powell franchise Harwin plc is a long-established supplier of hi-rel interconnect solutions. The company retains all essential production elements in-house at its Portsmouth, UK, facility, so is able to guarantee the highest levels of quality. Some years ago, the company introduced the Gecko
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