Follow these ten steps to getting the connector right

Paul Boughton

When it comes to reliable system operation, choosing the right connector is key. Follow these ten steps to research the ideal connector early in the design phase and you can positively impact the design, usability and cost. David Cianciolo reports.
The right connector can make your system smaller, lighter, and easier for the user to handle. It isn’t a place to take shortcuts, as the right connector system can help avoid the high price of recalls, repairs and lost customers.
Conducting adequate research on the connectors and cable must be done at the beginning of a systems design process to produce the optimal design. Follow these ten steps to research the ideal connector early in the design phase and you can positively impact the design, usability, and cost structure of your entire device.
1. Electrical Needs. Defining the electrical voltage and current requirements each contact will carry is the first step to selecting the ideal connectors for your device. You have to ensure that you not only have the right number of contacts, but that the contacts can carry the power demands of your application.
The size of the contact and the size of the wire dictate the current-carrying capability of a contact. Contact spacing, insulation materials, and the geometry of the insulator used to isolate the contacts dictates the voltage rating. [Page Break]
2. Adding Functions. After you identify electrical requirements, determine whether other functions can or should be added to your connector. Hybrid connectors are usually custom designed, but if you have the time to work with a manufacturer to develop a specific hybrid connector, it can be worth the effort.
The results will provide the end user with fewer connections and cables to manage. See if you can source a single connector that can carry more than one of the following: power, signal, coax, fibre, liquid and/or gas.
3. Termination Types. Termination types have a direct effect on the assembly process and the ability to seal a connector. Connectors with solder contacts are typically easier to seal against moisture ingress, while crimp contacts may offer better field reparability.
There is a trade-off between the two, so the final decision on which termination type to use is often made after discussions with your manufacturing and design groups.  
It’s important to know exactly how and where the connector will be used, and whether field reparability is a requirement, as this decision has a significant impact on the assembly equipment and processes used in manufacturing.
4. Environmental Sealing. If the connectors will be used in harsh operating environments, check the manufacturer’s IP (Ingress Protection) rating for sealing to dust and water at various depths and operating time frames. Make sure you understand the end use environment for your connectors, and then compare that scenario with the details behind the manufacturer’s IP rating.
Most of the IP designations have specific conditions, but the IP68 rating may be defined by each manufacturer differently. When looking for a connector with an IP68 sealing rating, inquire exactly how the manufacturer’s IP68 rating is measured.  
For a vacuum application, you may need a product sealed to a greater level than what is defined by the traditional IP ratings. These are defined as hermetic (airtight) sealed products.[Page Break]
5. Materials. Select the material of the connector housing wisely as this may impact reliability, weight, and cost. Brass connectors with nickel/chrome plating are traditionally more wear resistant and have longer lifecycles than many other materials. If weight is an issue, aluminium connectors may be an option. Consider plastics for limited reuse and disposable applications.
For aggressively corrosive environments or some food industry applications, stainless steel may be required. Don’t sacrifice reliability for cost when deciding what material you select. At this point, you should also review the operating temperature of the insulating materials used in the connectors you are evaluating.
6. Reliability Needs. Now that you’ve investigated the electrical, termination, sealing, and material requirements, it’s time to take a look at the frequency your user will connect and disconnect the device over its lifetime. If you require a very high number of mating cycles, consider a connector with 5,000 to 10,000+ mating cycles. This is especially important if a failed electrical connection can put lives at risk, such as in the medical or military environments. [Page Break]
7. Miniaturisation. There are some great things going on with miniaturization today, and you should take advantage of it where you can. It is possible to design in one connector today for an application that would have needed two or three connectors only a year ago, but you have to be careful. Look closely at the details in each connector, since those details become more important as the voltage and current increases.  
Compare models for pin size, number of pins, and functionality. Miniature connectors are nice packages that fit in small places, but only a few can carry power and signal.
8. Raw Cable and Assemblies. Once you have identified your connector, it’s time to define the raw cable and the cable assembly. Connectors are getting smaller all the time, so it’s becoming easier to inadvertently spec a small connector that won’t work with the larger cable you would like to use. You’ll have to look at both the cable and the connector together to make sure that they compatible.
9. Ask About Service and Delivery. Check for realistic delivery dates; delivery on custom connectors from any supplier will always be longer than selecting an off the shelf product. If you can use something that’s already designed, you will find it has shorter delivery. Reduced lead times may be available by modifying an existing design. If you decide that a custom connector is the solution you require, make sure that your supplier is committed to the project over the life of your device.
10. Engineering Support Can Save Time. Ask suppliers about the kind of support you can expect from their engineering and product development teams. Check out details about design and prototyping services. Letting someone else look at your device early in the design process often opens up options for cost-saving or time-saving ideas.
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David Cianciolo leads the Fischer Connector United States engineering team from their Atlanta, GA, USA. Fischer Connectors is based in Saint-Prex, Switzerland.

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