Interconnection Catch here
Selecting the best fi t connector for an application
With the continued roll out of Industry 4.0, the IoT, IIoT, security equipment and wide area networks (WAN) many electronic products and systems are being required to function reliably in harsh or even outdoor environments. “The need to select the right electronic connector for the job has never been more important,” says David Phillips of binder UK
W
hen considering the specifi cation and design-in of any type of electronic or electrical connector there are fundamental decisions
to be made – at the top of the list are the electrical and physical features required for the application.
The number of contacts and the current and voltage ratings required, together with the cable diameter, level of shielding and any environmental protection all have a direct infl uence on the connector choice. Other considerations include the desired method of cable termination, the required mating action and the space available both inside and outside of the product are also key. For this connector selection overview I will concentrate on contact choice, mating systems and environmental protection.
Contact options and termination methods
The materials used define contact strength, spring properties, electrical conductivity and operating temperature. High quality contacts use copper-alloys for contacts, brass for pins and phosphor bronze for sockets as these materials ensure good strength, conductivity and temperature
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stability. In addition, gold or silver plating provides high levels of conductivity and corrosion resistance and will ensure over 500 mating cycles for high-use applications. The required cable termination method also needs careful consideration and will depend upon the application and production quantities. While solder terminations provide the most secure and best electrical joint they require skilled operators. Crimp terminations provide a fast and simple method but require expensive crimp tools. For fi eld wiring or where in-service replacement may be required, screw termination provides the best solution.
Connector shell materials Brass is a very common material for the manufacture of general-purpose connectors as it offers great strength. For applications where weight or cost are key considerations die-cast
zinc or an aluminium alloy are often used. Panel builders and systems integrators are moving towards the use low cost, light and robust all-plastic connectors such as binder’s series 620, 720 and 770 (pictured) where polyamide is the preferred material, as it offers desirable characterises including being tough, non-abrasive and resistant to solvents and temperatures up to +120°C.
Mating systems
How often the connector will be mated, the security of the mating method and the environmental (IP) requirements required by the application will have a major infl uence on the type of mating system.
Snap-in connectors provide quick and simple mating and are generally the lowest cost solution. Recent developments mean that these can now be rated up to IP67 and provide an economic solution with high performance. Bayonet connectors offer a more secure mating although the design means they are usually restricted to IP 40 protection. Metal push-pull connectors tend to be expensive and the trend towards plastic versions has helped to reduce cost and provide a quick mating IP67 rayed connector with some protection against accidental un-mating. Screw connectors provide the ultimate protection against accidental disconnection and have excellent IP performance; however, they are generally the most expensive type of connector, especially in metal versions.
Environmental considerations The expected pollution around the connector is divided into four degrees. The first degree is where there is no conductive
pollution, as may be found inside a device or enclosure. The second covers non-conductive pollution and temporary condensation like that experienced by household appliances, while the third is conductive pollution that may, for example, be experienced with machine tools on a factory floor. The fourth degree is persistent conductive pollution caused by material such as dust and water which may be found in demanding industrial or outdoor environments. IEC60529 classifi es the degrees of protection against outside infl uences such as dust, foreign objects, moisture and water. The IP rating is split with the fi rst number (0-6) denoting resistance to solid objects and dust and the second number (0-9K) denoting resistance to water. Typically, industrial connectors are rated IP65 and above, with many being IP67 for temporary immersion in water or the ultimate IP69K protection from high pressure water and steam cleaning.
Making the best of it
Frequently left to the end of a design process the connector is in reality a vital component for the correct and safe function of any system and should be under consideration throughout the development of any product. A connector that is the right size, has the correct electrical characteristics, uses the best method of termination and mating for the application and is protected to the required level will optimise the performance and cost- effectiveness of any system.
binder-connector.co.uk Components in Electronics June 2021 17
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