This by Wendy Bourne, conector expert from Harwin-
Mixed Layout Connectors – Custom product at standard prices
By Wendy Bourne, technical support engineer, Harwin
Size, weight, performance, cost. Those are the key determining factors that influence the choice of interconnect system. In an ideal world a connector would be invisible electrically, take up no space, be weightless and cost nothing. But how then do you get signals in and out of an instrument? How can it be powered? What about coax connections?
Each element - power, signal, coax, even fibre optic - requires different challenges to be solved, so specialist individual solutions have been evolved to address the various challenges. The design issues get more complex if the application calls for the connectors to be used in rugged environments where extremes of shock, vibration and temperature are routine such as experienced in equipment used by the military, aerospace, oil and gas exploration, marine and other heavy industrial sectors. Such projects call for very robust electronic systems, since the equipment simply cannot fail – either because it cannot be replaced, such as the nano-satellite, or because it is a critical application such as any medical system.
For example, signal connections for harsh environments need to be small and lightweight, quick to terminate yet secure under challenging operating conditions. Many connector systems exist that have been specially developed for use in military or other high-reliability applications. Often they have outstanding shock, vibration, temperature and other signal integrity performance specifications. Unfortunately they also usually carry an outstanding price tag – with contact prices spiralling ever upwards depending on a number of factors. However, there is a large and growing demand for a high performance connector system that performs well under difficult environmental conditions, yet is priced in line with commercial products.
There are also many specially-designed power connectors, but they are often bulky, because of the need to carry high currents and deal with thermal issues. Coax connectors raise different issues: here the over-riding requirement is to stop interference, so high-performing complex shielding systems have been developed.
So, if you have the space available and weight is not an issue, simply choose the best-performing connectors for signal, power and coax and move onto the next design challenge. But what if you are space- and weight-restricted?
There is an even more pernicious problem. Many times interconnect is viewed as a relatively simple problem, so is not addressed until the latter stages of the design. This means that often there simply is not enough room for separate signal, power and coax connectors.
The solution would seem to be quite simple, and for some time industry has been calling for a reliable, high performance interconnect system that enables a mix of technologies to be incorporated into one connector. Such systems do exist, often in industry-standard formats, such as DIN 41612 or various circular styles. However, many of these are very restricted in the combinations that are possible, and often the contacts they employ mean that only relatively low power or signal carrying capabilities are permitted.
Harwin’s well-established high reliability Datamate range, a 2mm pitch cable to cable, cable to board and board to board connector family, has proven its credentials for use in harsh operating conditions many times, having been selected as the interconnect of choice on programs such as ‘Nano’ space satellites (also termed Cubesats) that measure just 10x10x10cm, NASA’s Robonaut, the Neutrino telescope buried deep in the polar ice, Bowman military radio, missile guidance systems, dialysis equipment and patient monitoring systems and Formula 1 telemetry systems.
Datamate includes miniature mixed technology versions. Mix-Tek Datamate offers an enormous number of configurations for signal, power and/or coax, effectively allowing the customer to design their own Datamate connector, specific to their application, by mixing and matching the required signal, power and/or coax contacts up to a maximum of 50 low frequency contacts or 12 special (coax and power) contacts.
Miniature Mix-Tek connectors feature power contacts rated for use at up to 20 amps. Signal contacts are rated at up to 3 amps and coax performs to 6GHz. High reliability is achieved via turned contacts, used in conjunction with Harwin’s four-finger Beryllium Copper contact clip.
Connectors are optionally available with quick-mate 101lok or jackscrew terminations for added security in applications which require extra contact security. They are available in Male PC Tail, Female Crimp, Male Crimp and Female PC Tail options. Mouldings are polarized and have a UL94V-0 rating. Mix-Tek connectors comply with BS9525-F0033 and CECC 75101-008.
By choosing a mixed technology connector which offers a great deal of flexibility, designers are effectively getting a custom connector at little or no price penalty, especially if you consider the mounting and logistical costs associated with using separate connectors.
Wendy Bourne is available to discuss designing mixed technology interconnect solutions on Harwin’s Live Online Chat at http://www.harwin.com/