EMI filter connectors, quite frankly, can 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. Another problem is design flexibility: achieving sufficient EMI noise protection may often 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. Ceramic filter arrays that are inserted into specially-adapted connector shells can take weeks to arrive, since they are all custom parts. They are also 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 connector length.
A new, ingenious solution looks set to confine bulky, expensive ‘kludged’ filter connectors to the electronics industry’s museum of horrors, as Quell – a 20 year old company based in Albuquerque, USA – has invented a new, simple retrofit EMI connector technology which is deliverable in under one week, and which 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.
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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 required 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. 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 unique elastomeric body and adaptive interconnect system suspends, isolates and protects the discrete electrical components. This allows 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 extreme abuse (severe misalignments, vibration, wrong pin sizes). Importantly, EESeal’s also create an environmental seal.
Since EESeals do not use a PCB or planar ceramic array construction, they offer major advantages when compared with traditional EMI filters. 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. Components and wiring are fully imbedded in protective silicone, so, for example, capacitors can’t ‘pop off’, and won’t be damaged 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; further there are 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. Finally, EESeals are usually lighter than PCBs or arrays.
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. Custom connector forms can be as easily accommodated as standard types. 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.
The new EESeal EMI inserts are available on a very fast turn-around from Astute Electronics, the leading supplier of electronic components and value added services.
