FEAT


ATURE


CONNECTORS


What to look for in a ‘waterproof’ connector When a customer asks for a ‘waterproof’ connector, it is often a mystery as to what exactly


T


they require. Unfortunately it is often also a mystery to them! hey just don’t know what they want and


often end up specifying a totally unsuitable product. In a world where, increasingly , RF, microwave and electronics products generally are used ext ernally , in harsh environments and in situations where fluid ingress is an issue, it is critical t hat the customer is clear on his requirement s and equally, the manufacturer/ supplier is an expert in the different methods of ensuring that the integrity of the seals are sufficient to meet the needs of the application. One area which is often ‘forgott en’ is the unsuitability of certain materials in certain environments. For example, Intelliconnect have developed, in conjunct ion with our supply partners products manufactured from materials such as Nickel Aluminium Bronze for salt wat er applications and special proprietary rubbers for sealing gasket s and O rings.


The following brief case study demonstrates some of the challenges that we first faced when developing our wat erproof P isces range: Back in 2004 a major international


manufacturer of Personal Locator Beacons, approached us and requested t hat we design for t hem a range of special TNC connectors. Simple enough, we thought, we can do t hat!


“Good”, said the Customer, but the quantities are quite small, in the hundreds, in fact”. “No problem there, we’ll make a one off if you


want it”!


“Yes”, said the (potential) Customer, “but they need to be waterproof (mated and unmated)”. “OK that’s fine, a piece of hermetic glass in the rear end will do the trick!”


“Ah no we’ve already had a look at those and t hey’re far too expensive, we want something to work to a depth of 10 metres (1 bar) for four hours but we don’t want it to cost too much more than a standard connector, oh and because it’s a safety related military product, we need it to be highly reliable... and we don’t want to pay an NRE charge”


“Umm ok, any thing else?” we asked in trepidation.


“Yes, we need product on our dock in eight weeks”


So, we had an interesting problem on our hands. To design, develop, sample, machine, plate assemble and deliver a range of four different connectors wit h a completely new feature, in the space of eight weeks! Our design teams in Crossville Tn and Chelmsford, Essex UK, set to work. The connectors themselves were relatively


re relatively simple


bulkhead jacks and right angle cable plugs. The problem, of course, was how to make them waterproof... and that the sockets and the cabled plugs both presented a different set of challenges.


28 MAY 2020 | ELECTRONICS


a) Wat erproofing the bulkhead jacks so that there was no ingress of water int o the beacon when unmated.


b) Waterproofing the plugs so that t here was no ingress of water into the cable, either through t he face of the connector or the cable crimp area.


c) To ensure that materials were capable of withstanding prolonged exp osure to salt water and still maintain a seal.


d) To design the product so that it was manufacturable and cost effective.


e) Above all t o prove the integrity of what we designed/made to t he highest possible safety levels because this was a potential life or death situation product.


Aft er many late nights, meet ings with t he Customer, transatlant ic t eleconferences, trials and t ests and a huge amount of advice from specialist vendors, solutions were arrived at. Like most great idea’s it was ultimately a very simple one. Early on in the design process, the use of O rings was mooted as a potential way of internally sealing the connect ors but was quickly discarded as being too simplistic and potentially unreliable. The sealing properties of PT FE (T eflon) was looked at, epoxy sealing was investigated, glass was reviewed, some very st range ideas were brainstormed and all were discarded. Were we to fail? No, failure was not an option. Our pride as engineers (not t o mention a nice order) was at stake here and we would not be beaten.


very st


But what t o do? We had brainstormed unt il we had very few brains left to storm! “What about t hat idea of using ‘O’ rings? “Let’s look at it


’s look at it again.”


....and therein the answer lay. With much help from our O ring vendor, a special material was specified which would conform t o sealing and other mechanical requirements, other component s were specially designed, FMEAs and design reviews were carried out and now we could finally make protot ypes.


Initial prototy pes were made (not without some considerable pain) and our Rube Goldberg style t est equipment was brought into play . Jacks were tested using air at a pressure of 3 bar for 12 hours (twice the pressure and time t


for 12 hours (twice the pressure and time t hat t he customer required) with no failures. The right angle cable plugs proved more difficult. T he int ernal sealing was fine but even with u sing glu e lined heat shrink sleeving t here was a small amount of water seepage into the cable after prolonged immersion under pressure. The solution here was to mould a special ‘boot’ over the connect


special ‘boot’ over the connect or and cable. / ELECTRONICS


ately it is often also a mystery to them! The primary challenges were:


Samples were duly despatched t o the


Customer and within day s t he good news came back that t hey were happy!


Seven weeks and five days after the original enquiry, we were able to del iver the first production quantity with t wo day s to spare. T he Intelliconnect P isces connector range was born. Since 2005, Intelliconnect has developed a wide range of solutions for Customers


waterproofing issues as well as having many ‘off t he shelf’ connectors and cables. Applications range from safety and det ect ion equipment to hearing implant s,


Each application has its own challenges and since this time Intelliconnect has developed a special pat ented sealing sy stem for cable connectors using a special crimp ferrule and developed its test facility t o work to a dept h of 60m (100psi/7 bar).


All components are sourced in USA or UK and assembly is carried out in Crossville for the North American market and in Corby, UK for the European market.


Products as diverse as Triax, SMA, N T ype, Nim Camac, TNC, BNC, MCX and C t ype have been produced and Int elliconnect have even produced a brand new push on sub-miniature interface. Pisces is now Intelliconnect’s fastest growing brand


So the next time somebody asks for a ‘waterproof’ connector make sure t


‘waterproof’ connector make sure t hey know what they are asking for. Or alternatively, get them to ask an expert!


Intelliconnect www.intelliconnect.co.uk


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