Connector technologies are evolving with the reliability requirements for harsh environment applications.
By Adrian Green, Director of Engineering, Amphenol ICC
Harsh environment applications present many challenges for electronics systems designers. Reliable operation in industrial and specialized commercial operations subject the connector and the overall system to a range of extreme temperatures, shock, vibration, and contamination from fluid and dust ingress. These environmental factors require alternative connector design considerations as manufacturers adapt or redesign standard connectors into more ruggedized versions specifically for harsh environments by updating component materials, testing different mounting configurations, and improving upon ingress protection requirements.
This article examines several examples of how rugged connectors evolved from standard versions, the developments that were devised to solve specific design challenges triggered by harsh environments, and future advancements anticipated for harsh environment connector technology.
Rugged USB Connectors Maintain Reliable Data and Power Transfer
Initially developed in the mid-1990s, USB connectors offered a standard connection, communication, and power supply interface between electronic devices and computers. USB connectors have become universal in consumer devices, but have also found new commercial applications, in part because of their ability to reduce cable clutter in harsh public safety, military, and manufacturing environments. Properly sealed connectors can prevent additional maintenance and downtime costs resulting from a cable connector’s failure on sealed devices that require protection against dust, moisture, and environmental contaminants. In addition, cable clutter can be a more critical issue in mobile deployments and other situations with high traffic areas surrounding the equipment. USB 3.0 and USB-C connectors solve this problem by replacing several product interfaces and enabling streamlined, reliable installations with fewer points of failure and smaller I/O interface panels.
In order to provide reliable data transfer functions despite the intense shock, vibration, and temperatures of harsh environment applications, several customizable adaptations can be integrated into the connector’s design. By incorporating an IEC-60529-IP67 corrosion-resistant seal — typically either consisting of silicon rubber or epoxy-based materials — USB connectors are able to ensure reliable EMI protection, as well as protection against water or dust ingress. In combination with lock-washer lugs, the ruggedized, through-hole construction provides the USB connector with additional mechanical strength against inevitable shock and vibration.
USB connectors are available in several types that provide unique benefits. For example, USB-A connectors are specially designed to provide a sealed adapter at the panel’s bulkhead. Moreover, USB-C connectors enable further flexibility by increasing the number of pins from nine to 24, which expands the USB’s universal functionality and allows for a reversible interface to prevent damage from inserting a cable in the incorrect position.
D-Sub Connectors Evolve With Sturdy Housing
Standard D-subminiature, or D-sub connectors, provide an electrical or communication connection primarily for video and audio applications. General consumer electronics have gradually migrated away from these connectors in favor of smaller form factors, but D-subs remain relevant in many non-consumer applications where their size, density, available configurations, and cost combination provide significant value for users.
In response to design requirement demands in evolving markets, D-sub connectors have been modified to withstand the harsh environments in outdoor, automation, industrial, and agriculture applications. Thermoplastic housing and metal die-cast shells provide resistance against high temperatures and exhibit increased strength and durability in the mated and unmated condition. These connectors meet both IP67 and IP68 standards, which define the connector’s protection against water and dust ingress as well as a capability to maintain a reliable connection in underwater depths of 25m for up to 24 hours. For space-constrained applications, a high-density version is available.
HDMI Connectors Combine IP67 and HDMI 1.4a Specifications to Withstand Water and Dust Ingress
High-Definition Multimedia Interface (HDMI) standard connectors transmit high-definition video and audio data from an HDMI-compliant source device to a compatible device, such as a computer or television monitor. HDMI replaced obsolete analog interfaces, revolutionized high-definition (HD) digital multimedia signal transfer, and established a new, universal standard.
Portable computers, broadcast equipment, security systems, outdoor audio/visual equipment, and medical imaging systems require HD audio/visual signal transmissions in environments where standard HDMI connectors are unable to perform reliably. Rugged HDMI connectors combine a standard HDMI interface with both an IP67 rating and HDMI Specification Version 1.4a electrical performance compliance for a dependable connection in unique, harsh conditions.
RJ Connectors Protect Against Leakage in Extreme Temperatures
Registered Jack, or “RJ” connectors, were originally developed in the 1970s under a Federal Communications Commission (FCC) order to standardize the interconnection between telephone equipment and customer premises equipment. Primarily based on miniature modular connectors, RJ connectors establish a standard telecommunication network interface for connecting voice and data equipment. Known for their use in consumer telephone and Internet connection applications, RJ connectors are also employed in systems that must withstand harsh environments, such as telephone and data transfer cables for telecom equipment, tele-maintenance, industrial process control, airplane equipment, tactical radios, battlefield and naval communication, GPS positioning equipment, and other data acquisition and transmission applications.
One way connectors are engineered to withstand harsh conditions is with epoxy-free designs that protect against leakage triggered by extreme temperature changes. Manufacturers also implement rugged, IP67-rated shells to protect connectors against water and dust ingress. These shells can be expensive, so manufacturers are also using lower-cost conductive gaskets, which have the added benefit of an IP68 rating. Optional accessories can be combined with RJ connectors to deliver added protection and performance benefits, including dust covers or caps for additional mating area coverage and extended IP68 protection against shock and aggressive fluid ingress.
RJ connectors are available in several mounting positions to accommodate users’ mechanical specifications, including right angle for standard or reverse pin orientation, and vertical for top entry in rear- and front-mounting options.
Harsh Environment Connectors Rely on Design Innovation
IP67-rated boots are an example of a cost-effective connector design enhancement to uphold reliable performance in harsh environment applications. They offer additional protection for a variety of standard I/O commercial products, including modular jacks and USB connectors for telecom, medical, industrial, automation, marine, agricultural, and construction equipment applications. Crafted with high-grade, weather-resistant material with UV-resistant options, IP67 boots accommodate standard and field-terminated cable assemblies and deliver additional trusted IP67-rated performance for situations that put the I/O interface at risk to fluid ingress.
Continued innovation in electronic components is driving the development of harsh environment electronics. Connector reliability in extreme temperatures continues to increase with sustained research and development for improved methods in extending temperature ratings. Gaskets and seals are also experiencing design innovations to further improve upon connection vulnerability faced by deeper, more prolonged water submersion. For example, gaskets and seals can be designed internally to the connector, and new resin-impregnation technology helps improve handling of the expansion and contraction of the connector materials while maintaining seal integrity. The future of rugged connector design will continue to depend upon evolving standard connector specifications and increasing protection against harsh environmental factors.