FEATURE CABLES & CONNECTORS TAKING A


new perspective on EMC


connector design connector design


To overcome the issues faced by users of EMI filter connectors, a new solution has been developed that provides an EMC solution capable of surviving extreme environmental abuse. Gary Evans from Astute Electronics looks into the technology


embedded into a silicone rubber insert that matches the size, shape and pin configuration of the connector that needs to be filtered. Users specify which EMI filter elements, if any, are required for each pin. To ensure integrity of connection, all external and internal wiring is fully plated with 50-70 microns Au over Ni flash. In addition, the custom inserts are easily and quickly inserted into standard connector bodies, without the need for any special tooling or soldering, forming an effective EMI filter and an environmental seal. EESeal’s elastomeric body and adaptive


E


MI filter connectors can, quite frankly, be a pain. No one designs a


system around a connector, so often by the time EMC is considered there is very little space left for traditional, bulky, filter connectors. Furthermore, achieving sufficient EMI noise protection may require the system to be fully developed before the problem can be accurately assessed, and any last minute system changes may require a complete rethink. Being custom parts, ceramic


filter arrays that are inserted into specially-adapted connector shells can take weeks to arrive, and can also be expensive and fragile. Worse, retrofits are difficult to achieve, since adding EMI filtering almost always requires a complete new connector body – assuming you have room enough to accommodate the extended length. However, this may be set to change


with the introduction of a simple retrofit EMI connector technology. Invented by a company based in Albuquerque and available in the UK from Astute Electronics, this is deliverable in under one week and can be retrofitted into existing connectors very simply, even in the field, providing an effective EMC solution that will survive extreme environmental abuse. The technology can also be used to provide surge suppression.


BEHIND THE TECHNOLOGY Quell’s EESeal technology uses filter components – resistors and capacitors –


16 NOVEMBER 2015 | DESIGN SOLUTIONS


Quell’s EESeal technology uses filter components – resistors and capacitors – embedded into a silicone rubber insert that matches the size, shape and pin configuration of the connector that needs to be filtered


interconnect system suspends, isolates and protects the discrete electrical components, allowing the entire assembly to change shape in response to external forces without compromising the filtering or the electrical and mechanical integrity of the system. The silicone body acts as a conformal coating and electrical isolation for the components suspended within it, and the natural compressive forces are exploited to create re-usable electrical contacts that can withstand such issues as severe misalignment, vibration, wrong pin sizes and so on. They also create an environmental seal. EESeal’s do not use a PCB or planar ceramic array construction. They do not need any modification of the body shell, and do not create air pockets or defeat existing environmental seals. 3D construction, unlike 2D PCB solutions, does not risk violating applicable MIL standards for spacing, conformal coating, pad-size, etc. The components and wiring are fully


embedded in protective silicone so, for example, capacitors can’t ‘pop off’,


and won’t be damaged or cracked during installation or use. The silicone construction also withstands severe temperature ranges and exposure to many deteriorating influences such as ozone, chemicals, aging and UV. There are also no spring metal contacts (BeCu) to degrade or become brittle due to overstress during installation – EESeal contacts accommodate severe misalignment and mismatch without loss or performance; and they are usually lighter than PCBs or arrays.


MEETING DEMANDS EESeal EMI inserts can be custom- manufactured in as little as seven days and will fit into many different hi-rel connector formats – including MIL-C- 38999, MIL-C-26482, MIL-C-5015, MIL-C-83723, ARINC, Eurofighter, Lemo, Centronix, MDM, D-subminiature, Micro D-subminiature and DIN. Not only can custom connector


forms be as easily accommodated as standard types, but all types of filtering element can be included – MOVs and other transient voltage suppression (TVS) diodes can also be included within the silicone inserts, offering surge protection as well as EMI.


Astute Electronics T: 01920 897324 www.astute.co.uk


/ DESIGNSOLUTIONS


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