The Importance of Connectors

Connectors are essential electro-mechanical products that are used, along with wire and cable, to connect or disconnect electronic and electrical devices and circuits and allow signals and power to pass back and forth. That is the textbook definition, but it is far from the whole story, because connectors are some of the most prolific devices that are used in thousands of products and across multiple industries to make things work, move information, and connect people.

So, let’s go back to the basics. Electrical and electronic devices need power to operate and signals to run. Many devices, aside from perhaps laptop PCs, are not monolithic, however. They offer ease of use and portability by separating functions into discrete, smaller packages. At some point, however, these diverse packages must be linked together in order to perform a task.

Thus, computer peripherals must be linked to the host. Stereo speakers must be linked to receivers. Guitars must be linked to amps. Phones must be linked to a network. Electrical actuator valves in a process control system must be linked to the grid, and so on. The other part of the equation is that, at some point, these products and systems may also need to be dismantled in order to be moved, or upgraded, or stored. Enter the connector. A device that is either metal or plastic that contains multiple pins or contacts which mate with sockets in a corresponding receptacle to form a connection and allow electrical signals, or light signals as in the case of fiber optic connectors, to pass. They are typically paired with wire or cable to form an assembly, but not always. Connectors can also be mounted on PC boards allowing direct connection of memory cards or video boards without using cables. The basic structure of most connectors includes the internal contacts that mate with sockets to form a connection; some type of insulator that encapsulates the contacts and separates them from each other and the body of the connector; the shell, or outer cover of the connector which holds all the internal parts, provides alignment when mating the connector halves, and can secure the connector to its mate; and accessories that may be used to further secure, guide, or seal the connector.

The usefulness of connectors has led to a vast catalog of modern devices that work in many different ways and include features to make them more functional, easy to operate, and reliable in many different environments. Here is a quick (but not necessarily complete) list of some of the connector device names you may encounter in your search for products to meet your application needs:

• Circular: cylindrical connectors with a round interface that are highly reliable and resistant to accidental decoupling.
• Audio: small connectors to transfer low power audio signals, including plugs, jacks, and adaptors in different mounting styles.
• Power: robust plugs and receptacles used to transmit power only.
• Terminal Block: modular, customizable, blocks that organize multiple wires and contacts together for power or signal transmission.
• USB: devices that support the Universal Serial Bus (USB) standard interface for personal computers and consumer electronic devices. Available in multiple configurations from micro to original standard.
• HDMI: devices that support the High-Definition Multimedia Interface (HDMI) standard used to transmit compressed or uncompressed video and audio signals in entertainment or communications systems. Available in mini, micro, and standard sizes.
• Modular: commonly used in telephone systems, these include plugs and jacks that employ registered jack (RJ) twisted pair cables for data transfer and low speed serial connections. They can also be referred to as RJ or Ethernet connectors. Customizable in the field for ease of use.
• RCA: also known as phono connectors, these single wire, plug and socket connectors were developed by RCA for use with coaxial cable and used mainly in audio and video systems.
• DIN: devices that support the German National Standards Organization (DIN) standard. They are circular and keyed to ensure connect insertion for audio and communication equipment.
• D-Sub: devices containing two or more parallel rows of contacts housed in a D-shaped shell to ensure correct insertion orientation.
• Fiber Optic: these are typically round or square connectors used to terminate the optical fibers used in communications systems and to transfer data.

As is apparent from this list, there are many different standard connector options available to match many different applications. If your needs are somewhat out of the ordinary, most manufacturers also offer options to customize connectors to match a specific application. This is usually accomplished by varying the number or placement of contacts, the addition of grounding or enhanced insulator components, or custom locking or indicator features.

The wireless revolution essentially goes back to the development of radio technology in the 1800’s, but mobile broadband, Bluetooth, and WiFi technologies have allowed modern wireless adoption to soar, particularly with IT and entertainment products. Using hard connectors along with wire or cable for signal or power transfer, however, still offers many benefits over wireless.

Hardwired interconnects offer increased security and enhanced privacy versus wireless, and can even deliver both signals and power through a single connector, if needed. Using hard connectors can also avoid or reduce the problems associated with network access, bandwidth, and signal interference, particularly in industrial environments which tend to introduce plenty of electrical noise and other interference.

Engineering standards that apply to connectors not only allow for the efficiencies and economies of standardization, but also address safety concerns, particularly in the case of handling electric current. Some of the organizations whose certification marks you may encounter when evaluating connectors include:

• UL – Underwriter’s Laboratories
• SAE – Society of Automotive Engineers
• IEC – International Electrotechnical Commission
• EN – European Norm
• MIL/AERO – Military standards developed by the U.S. Department of Defense
• DIN – Deutsches Institut fur Normung (German national standards organization)
• ANSI – American National Standards Institute
• CSA – Canadian Standards Association
• ISO – International Organization for Standardization

There may be other certifications not listed here that are applicable to connectors for use in individual countries.

The criteria involved in the connector selection process can be somewhat daunting, as each individual type or style of connector can often have many different iterations depending on how many versions of the underlying technology standard have been issued. For example, there are five different versions of HDMI connectors that support the dozen or so updates that have been released on the original HDMI standard, which was published in 2002.

While the movement of data or power between devices or systems can appear simple, there are many options to consider in a design. In order to sort through the various connector models, styles, features and accessories that are available today, some criteria that may need to be addressed include the following:

• Size – nano, micro, mini, standard or other
• Power Rating – the maximum voltage or current that the connector is designed to safely carry
• Number of Contacts – how many pins or contacts your design requires
• Contact Size – physical dimensions of the individual contacts corresponding to the gauge of the wire or cable used for the interconnect
• Gender – connectors are typically sourced as a mated pair of a male and a female
• Insertion Frequency – the number of mating cycles a connector can handle before failure (also known as contact durability)
• Data Transfer Rate – how fast data can be moved by the connector/cable pairing (also known as signal transfer rate)
• Coupling Style – how the connector is securely mated to the end product (examples include bayonet, threaded, quick-disconnect, push-pull, etc.)
• Termination – how the connector will mate with the wire or cable used for the interconnection
• Backwards Compatibility – the capability of a connector to function with earlier versions of the device released under the same technology standard
• Manufacturability – how easily a connector can be integrated into either your manufacturing process or your field installation procedures

Outside of the basic functionality of standard connectors, there are additional features that are available on the market to suit specific needs. These include environmental sealing for protection against harsh environmental elements like heat, vibration, radiation, and weather. Ruggedized products can feature combinations of watertight seals, special jackets and boots, shielding from EMI or other interference, special coatings, and grounding systems. Connectors can also offer a keying function, which adds tabs, indents or other mechanical means to prevent incorrect mating. Finally, various locking mechanisms are available to ensure that connectors do not separate from their mating halves or from an end device.

When it comes to connectors, it is probably easier to list the uncommon applications as opposed to the common ones, since they are so ubiquitous. However, some of the applications you may know of, and some you may not, include:

• Computer systems and networking components
• Audio and video communication systems
• Telephone systems
• Security systems
• Consumer, commercial and industrial vehicles
• Other transportation systems
• Power distribution
• Data centers
• Process control systems and factory wiring
• Sensor networks
• Medical equipment
• Military and aerospace systems
• Robotics
• Unmanned aerial vehicles
• Test and measurement equipment
• Video game systems

This list is by no means exhaustive, and new applications obviously arise daily with the ongoing march of technology and the continuing need for interconnection solutions.

The first electrical connectors were developed in the late 1800’s, for use in the growing number of households and businesses with electric service. At about the same time, plugs and sockets (connectors) for portable appliances were invented. The first MIL-SPEC connectors were developed by the military in the 1930’s to meet the needs of the Army and Navy. Western Electric invented the modular connector for the Bell System in the 1960’s. The USB interconnect standard was developed in the mid 1990’s and Apple was the first to employ USB connectors in its computers in 1998.

Obviously, connectors have evolved and been in-use for many years, and their styles, designs, functions and features continue to grow and adapt to developments in technology and market demands. They have proven to be reliable electrical and electronic components that perform well in environments that range from the home, to the factory floor, and even into space. Connectors on the Voyager I and II probes have even left the confines of our solar system and ventured into interstellar space. Connector manufacturers today offer a very broad array of product types and features that can meet challenging applications, plus add significant value to many products and systems available worldwide.