The use and maintenance of electronics in locations subject to extreme temperatures, shock & vibration, dust, water, chemicals, radiation, and other hazards presents ongoing challenges for engineers and designers. Choosing the right components for high reliability and long life while balancing cost requires careful consideration. In Harsh Environment/ Remote Locations, the latest eBook from Connector Supplier, industry experts share their knowledge on how to manage those challenges with a look at specific conditions, interconnect solutions, and applications.
HARSH ENVIRONMENT/ REMOTE LOCATIONS
RF Interconnects for Harsh Environments Amphenol RF Harsh Environment Solutions feature quick mating and quick disconnect RF connectors, blind-mate connector systems, and customized hybrid solutions supporting RF, signal, and power
HARSH ENVIRONMENT/REMOTE LOCATIONS
The use and maintenance of electronics in locations subject to extreme temperatures, shock & vibration, dust, water, chemicals, radiation, and other hazards presents ongoing challenges for engineers and designers. Choosing the right components for high reliability and long life while balancing cost requires careful consideration. In Harsh Environment/ Remote Locations , the latest eBook from Connector Supplier, industry experts share their knowledge on how to manage those challenges with a look at specific conditions, interconnect solutions, and applications. Please enjoy this edition, the first of three 2023 eBooks. Our next eBook, Connectors on the Move: Automotive & Transportation , will be available in June 2023. This collection will explore the role of interconnects in all aspects of automotive and transportation applications, from engine and drivetrain to EVs/HEVs to in-cabin systems for passenger vehicles, fleet vehicles, heavy equipment (agriculture, construction, two-wheeled transport, fleet vehicles), as well as commercial air and rail. In addition, this eBook features an array of relevant connectivity products designed for harsh environment and remote location applications. Contributors include Axon’ Cable, Carlisle Interconnect Technologies, EDAC, ept USA, Greene Tweed, Interstate Connecting Components (ICC) , Mouser Electronics, Phoenix Contact, Powell Electronics, Samtec, Smiths Interconnect, TE Connectivity, and Teledyne Reynolds. Please subscribe to our weekly e-newsletters, follow us on LinkedIn, Twitter, and Facebook, and check out our eBook archives for more applicable, expert-informed connectivity content.
Managing Editor Amy Goetzman
Associate Managing Editor AJ Born
Creative Director Raine Arzola
32 FIBER OPTICS: THE MOST EFFICIENT WAY TO TRANSPORT DATA, EVEN IN HARSH ENVIRONMENTS POWELL ELECTRONICS 29 PRESS-FIT TECHNOLOGY AS A CONNECTIVITY SOLUTION FOR THE HARSHEST ENVIRONMENTS EPT USA
7 REMOTE LOCATIONS: HOW TO DESIGN INTERCONNECT SOLUTIONS FOR HARSH ENVIRONMENTS AXON’ CABLE 12 REAL-WORLD REQUIREMENTS MAY EXCEED STANDARDS FOR CONNECTORS USED IN HARSH ENVIRONMENTS CARLISLE INTERCONNECT TECHNOLOGIES UNIQUE CONNECTIVITY CHALLENGES OF HARSH ENVIRONMENTS AND REMOTE LOCATIONS 19 SHOCK, VIBRATION, AND CORROSION: AVOIDING DAMAGING EFFECTS IN HIGH-PERFORMANCE CONNECTORS SAMTEC
INTERCONNECTS FOR REMOTE LAND AND SPACE APPLICATIONS
47 PRODUCT BRIEFS A VARIETY OF PRODUCTS FROM TOP CONNECTOR SUPPLIERS HIGHLIGHT CONNECTIVITY SOLUTIONS FOR THE UNIQUE NEEDS OF HARSH ENVIRONMENT AND REMOTE LOCATION APPLICATIONS. 43 ENABLING GLOBAL INTERNET CONNECTIVITY WITH LOW EARTH ORBIT SATELLITES TE CONNECTIVITY (TE) 39 REMOTE TOWERS RELY ON HEAVY- DUTY CONNECTORS – A CASE STUDY PHOENIX CONTACT USA
INTERCONNECTS ADDRESS SPECIFIC HARSH ENVIRONMENT NEEDS
24 TOP SEVEN CONSIDERATIONS FOR D-SUBMINIATURES USED IN HARSH ENVIRONMENTS AND REMOTE LOCATIONS EDAC
UNIQUE CONNECTIVITY CHALLENGES OF HARSH ENVIRONMENTS AND REMOTE LOCATIONS
REMOTE LOCATIONS: HOW TO DESIGN INTERCONNECT SOLUTIONS FOR HARSH ENVIRONMENTS PIERRE-YVES MIKUS, PHD, R&D MANAGER ARMAND HATTAT, SALES ENGINEER ˇ
CHRISTOPHE TISSERAND, SALES MANAGER SANDRINE HERMANT, MARKETING MANAGER AXON’ CABLE
Electronic systems and equipment are often used in hard-to-reach locations. When it comes to remote locations, space often comes to mind, because nothing on Earth is as remote as the red planet Mars or deep space. Closer to us, we can think of mountain-top observatories, deep sea rovers, or inter-continent data links. The common issue among technologies used in these challenging operating conditions is the extreme difficulty – if not impossibility – of accessing and maintaining electronic systems and related interconnects, including cables, cable assemblies, and connectors. But this is also true in many other applications. Environmental conditions can prevent human technicians from accessing components for repair or replacement, even when they are actually close at hand. Radiation, vacuum, pressure, and extreme low or high temperatures are examples of factors that prevent easy access and maintenance. Operating conditions must be taken into account when designing such applications.
HOW NUCLEAR OPERATING CONDITIONS INFLUENCE THE DESIGN OF INTERCONNECTS The nuclear environment is a good illustration of the severe operating conditions to which interconnects can be subjected. The presence of radiation, vacuum environments, and extreme temperatures challenge the life span and performance of interconnect solutions and insulation materials with obvious limitations on
ENVIRONMENTAL CONDITIONS CAN PREVENT HUMAN TECHNICIANS
FROM ACCESSING COMPONENTS FOR REPAIR OR REPLACEMENT, EVEN WHEN THEY ARE ACTUALLY CLOSE AT HAND
personnel access. Both mechanical strength and electrical performance will be affected by this extreme environment, leading to premature aging and eventually failure of equipment. Small Modular Reactors (SMR) and other newer reactors in development have exacting requirements, which makes the design of interconnect solutions even more challenging. Additionally, high temperatures and radiation can degrade components that initially meet these requirements. It is therefore of paramount importance to understand how each material ages under specific conditions, so that as its characteristics evolve, required performance is maintained throughout its expected life on the system. Insulating materials specifically designed to resist radiation and maintain guaranteed electrical performance should be employed in these designs. Although traditional radiation-resistant insulating materials tend to be very stiff, which makes the cables more difficult to install in the system, new innovative materials allow for a more flexible interconnect while maintaining very good radiation resistance.
Example of a flexible 1 kV Poliax insulated cable assembly terminated with an Axon’ Cable round connector. This cable assembly, which is designed to resist 6 MGy radiation, is used in the Atlas detector (CERN particle collider). The confined installation area requires flexible cable assemblies with compact connectors.
interconnect. These kinds of applications usually require high voltage with partial discharge-free insulation. Here again, the choice of materials does really matter, but even more important are the construction of each interconnect component and the design of the interfaces. The way the cable elements are constructed and assembled provides the resistance to the huge pressure exerted in the bottom of oceans.
Intervention on site by an Axon’ Cable engineer: The density of cabling in the Atlas detector makes it difficult to access the links. (Photo courtesy of CERN)
PROTECTING PEOPLE AND MATERIALS Inside a manned underwater vehicle, very different constraints have to be taken into account. There is no direct exposure to pressurized salt water, but within the confined vehicle environment even the slightest risk to the safety of the crew must be considered. The key issue is clearly to avoid any risk of fire, and to mitigate the consequences of a potential fire while saving space and facilitating integration with a miniaturized flexible cable. The main objective is, therefore, to select materials that will not burst into flames, and that will not release opaque, toxic, or corrosive fumes when burning. In this case, the best option is low- Heating cables for pipelines made by Axon’ Cable. This custom-designed cable is made with a special insulating material able to provide the best compromise between electrical and mechanical performance. The custom process provides pressure resistance over very long lengths.
INTERCONNECT SOLUTIONS FOR UNDERWATER EQUIPMENT: WATCH OUT FOR THE PRESSURE! Remote locations can also mean subsea applications. Common examples include systems installed on the seabed, like pipelines or data cables; vehicles, such as submarines or rovers; and surface installations like oil rigs and ships. In terms of constraints, high mechanical stress related to pressure is combined with corrosion caused by salt water. In this case, waterproofing plays a key role in maintaining the integrity of the electrical insulation around the cable or High-voltage cables and splices (>50kV) made by Axon’ Cable for the ITER nuclear fusion reactor. The system consists of cables insulated with an Axon’ special material that requires an innovative installation process. These cables are connected in a glass fiber/resin splice that can withstand high-energy radiation and extreme temperature variations (cryogenic temperature of 4 K).
smoke halogen-free insulating materials with fire- retardant properties.
In space-restricted areas, flat flexible cables (FFC) designed to connect PCB or devices including actuators are a good solution to save space. They are usually insulated with polyester or with polyimide for a higher temperature resistance. For repeated movements of the robot, high flexibility of the FFC can be achieved with very thin conductors and very thin insulating material. Axon’ cable assembly made with a Flexorad high flex life RF cable terminated with round connectors. The high flexibility of the cable enables the arms of the rescue robots to move easily. The cable shown here is also radiation resistant.
WHEN THE ACCESS IS TOTALLY IMPOSSIBLE When everything has been done to protect the safety of personnel and optimize the lifespan of equipment and this is still not enough, the last resort is to send in robots as an extension of the human arm. These robots, which handle or maintain the electronic systems, are subjected to the same harsh environment, with the added challenge of needing good flexibility to allow for their movements. In this case, interconnects, including cables and cable assemblies, have to provide flexibility and ruggedization against the environmental challenges to provide sufficient longevity and reliability. In most robotic applications miniaturization and weight-saving properties are also a priority. Axon’ low smoke and halogen-free composite cable with fire-retardant properties is used in submarines. Its high flexibility allows for easy installation. The low-smoke, halogen-free, and fire-retardant properties of the cable protect the crew.
Flexlife test of Flat Flexible Cables designed by Axon’ Cable. Extra flexible versions with 25 µm thick conductor and very thin polyester can reach 70,000,000 cycles (flexlife) with a 10 mm bend radius. This is an ideal solution for dynamic applications including robotics.
components can work in different environments but they all serve the same function. It is of paramount importance to consider the whole interconnect solution as a fully integrated system, rather than a sum of components, especially when it comes to extending the lifetime of the system or eliminating the need for maintenance.
INTERCONNECTS ARE MORE THAN A SUM OF COMPONENTS If not properly designed, interfaces between devices in electronic systems can be the weak point. This is even more critical in severe environments, including remote locations. For example, a hermetic system might need a hermetic feedthrough and matching interfaces with both air side and vacuum side cables. All different
Visit Axon’ Cable to learn more.
Example of a complete solution with Axon’ Cable’s HermAx hermetic connectors and feedthrough in a hermetic system.
REAL-WORLD REQUIREMENTS MAY EXCEED STANDARDS FOR CONNECTORS USED IN HARSH ENVIRONMENTS HARRY FENTON, PRODUCT MANAGER CUSTOM CONNECTORS
Aerospace, defense, and industrial customers continually raise the bar for their performance requirements for harsh environments and rugged duty connectors. Not only must the current requirements be met, future requirements for durability and data transfer performance must be anticipated with forward-looking component designs. The design and performance envelope is continually pushed as customers rarely seek “just enough” performance. Their need is always for more performance and for connectors that will support future technology growth. In today’s market, industry technical standards or MIL-Spec standards may not be enough to match real-world technical performance demands. In most applications, standards are more likely to be the minimum criteria for compliance, and the real expectation is performance beyond a standard. MATT TALLEY, DIRECTOR OF ENGINEERING CARLISLE INTERCONNECT TECHNOLOGIES
Innovative, faster, and longer-lasting components are needed to meet these customers’ expectations.
The challenges for the connector manufacturer to meet customer expectations are many. Designs must suppress the environmental impact of exposure to humidity, temperature extremes, corrosive fluids, and fine abrasive particulate matter like sand, either individually or in combination. In addition, connectors must survive tens of thousands of hours of low- to high- amplitude vibration, especially in engine, rotorcraft, mining, and downhole drilling environments. The physical stress from crews performing maintenance is another challenge. During routine maintenance activities of component inspections, LRU replacement, or equipment upgrades, connectors will be cycled, disconnected, and
reconnected. Every time the connector is separated and reconnected creates an opportunity for it to be inadvertently damaged. Coupled with the need for rugged construction is the ever-increasing requirement for consistent high-rate transfer with very high signal integrity under the harshest of environmental, temperature, and vibration conditions. HIGH-TEMPERATURE CONNECTORS (THE HOTTER, THE BETTER) High-temperature applications are among the most challenging for harsh-duty connectors. High-temperature connectors require intricate specialized designs and materials to meet the exacting specifications for reliable, high-fidelity signals for critical operations in high-temperature environments. The mission profiles for high- temperature connectors include applications in high heat zones inherent to engine environments, oil exploration and geothermal environments, solar panels, power generation, industrial, and military/defense applications. Common interfaces are probes, signal transfer devices, thermocouples, and pressure transducers. High-temperature connectors are frequently configured to fit in industry-standard MIL- DTL-38999 or EN2997 connector shells variably
sized for two or three contacts. The MIL-DTL-38999 is the most common industry standard and details a temperature range -65 °C to +200 °C.
CarlisleIT Ultra High Temperature Connectors
Certain EN2997 specification connectors will support the maximum 260 °C temperature supported by the specification. Some connector manufacturers cite a 300 °C maximum temperature for their high-temperature products. One leading manufacturer of custom connectors can supply an ultra-high-temperature EN2667 connector with a 405 °C maximum continuous duty, 450 °C maximum limit connector (greater than double the MIL-DTL-38999 high limit specification), and 145 °C higher than the standard EN2667 specification. The materials used for a high-temperature connector need to be physically durable and dimensionally stable in high-heat environments. Titanium is an optimal shell material offering superior corrosion resistance, conductivity, and
High-Performance Interconnect Solutions & Products to Meet the Critical Needs of Your Industry. At Carlisle Interconnect Technologies, we do more than make advanced interconnect technologies for a spectrum of industries. We deliver the critical connections and products that make amazing performances possible.
lightweight qualities in high-heat applications. Plated steel shells can be used, but the long-term durability of plated surfaces can be compromised by heat and by the physical effects of scratches and abrasions. A simple scratch in a plated surface will expose the bare base material to corrosive environments. In contrast, a scratch in a titanium component is a minimal concern due to the corrosion-resistant qualities throughout the base material. The core of the high-temperature connector is typically a ceramic insert which provides heat resistance and stability. However, ceramic materials are vulnerable to cracking due to vibration or shock loading and may have limitations when used in a high vibration or shake load environment. The most successful high-temperature connectors use exotic high-specification composite ceramic materials which balance vibration resilience and high-temperature performance. Ultimately, high-temperature connectors must provide reliable, high-speed data transfer between the launch signal and receiving signal devices. Connecting cables that can sustain high data transfer rates over long wire run lengths is important to the equation, but the connectors are critical components at the launch signal and receiving signal connection. Overall, the entirety of the connector design (temperature limits, termination features, and resistance to EMI and environmental factors) defines the connector, not just one specification. 38999 HARSH-DUTY CONNECTORS The MIL-DTL-38999 specification is the most common harsh-duty connector and is found in
virtually all aerospace and military applications and a number of industrial applications. A tried- and-true design, the MIL-DTL-38999 has roots in designs and specifications implemented 75 years ago. It is safe to say that MIL-DTL-38999 specification connectors will remain in mainline production throughout and beyond the lifetime of anyone who is reading this now. The 38999 is successful in that the common features, such as physical interface, mounting, technical specifications for conductivity, EMI, and environmental factors, are the same over a range of connector diameter sizes, small to large. Base materials of steel, aluminum, or composite materials are common, as well as specialty surface finishes for cosmetic and environmental purposes for all manner of harsh environments and rugged duty applications. In short, the 38999 connector offers no surprises and is an industry standard due to its wide range of proven characteristics.
Octax® connector shown with MIL-DTL-38999 configuration
The features that make the 38999 connector an outstanding choice for harsh, rugged duty may result in some compromises and limitations for applications. However, engineered solutions ensure this connector’s ongoing viability.
For example, the inherent ruggedness of 38999 can potentially make these connectors too heavy for use on weight-critical airframes. This issue can be mitigated by using lighter, lower-cost composite material connector shells, which can reduce the weight of an assembled connector by 20%. Individually that doesn’t seem like much, but large aircraft can use many hundreds of connectors, and the weight savings add up. Composite connectors are gaining wider market acceptance due to the balance between light weight and rugged duty performance. The physical properties of the 38999 connector can also be a challenge for data transfer. Standard design 38999 connectors will provide good 1 Gb/s signal transfer. However, modern designs for small multipin, segmented connectors, and high signal density connectors can provide 10 Gb/s and fit within 38999 shell sizes. These high- density connectors, by virtue of their design, will outperform standard 38999 connectors in harsh environment applications which require very high data transfer rates. REPAIRABILITY The repairability features of a connector are every bit as important as the performance ratings. Connectors must have the capability for rapid repair and quick return to service in applications such as passenger planes that fly on tight schedules; delays or service interruptions are unacceptable due to their cascading effect and the subsequent high financial impact. RUGGED-DUTY PERFORMANCE WITH
to manufacturer. Some connector and wire assemblies are not field repairable and require the complete replacement of a cable assembly. The affected cable assembly is returned to the factory for repair, or a spare cable assembly is installed to keep the affected system up and running. This makes sense for some defense articles where field repair is not practical and removal and replacement can be accomplished quickly. Complete replacement is not a good option for industrial or commercial aircraft applications in which accessibility is difficult or the length of cable assemblies makes it impractical. The most effective solution, in that case, is field-repairable connectors that can be serviced by technicians on-site. Field-repairable connectors employ various service methods. Several manufacturers require special service parts and special tools to accomplish repairs. The most practical solution is a connector that can be repaired with commonly available avionics indent crimp service tools and AS39029 contacts. An unusual but critically important consideration for repairable connectors is whether the connector requires a heat gun for shrink tubing or curing of potting materials. Prior to making any repair to a passenger aircraft requiring heat or a flame source, passengers must deplane, and the aircraft must be towed to a fire-safe area with firefighting equipment on standby. A simple repair for a connector, therefore, can become very complicated and take many hours, removing the aircraft from service for extended periods. Crimp connectors assembled with common avionics hand tools eliminate the complexities of fire-safe repairs.
Within the industry, the repair schemes are not entirely standard and can vary from manufacturer
HOW TO SELECT A HARSH ENVIRONMENT CONNECTOR Connector selection for long-term use requires consideration of the following qualities: • Durability • Weight • Signal and data density relative to size • Capacity for future expansion • Signal integrity • High-limit temperature ratings for maximum performance and future expansion • Price versus performance The choice of connector is not always a simple matter of whether the connector meets a standard specification at the lowest cost. The least expensive connector will probably meet the minimum requirements but will fall far short of real-world extended requirements. Connectors that are more expensive on a single-part basis may be the best value in terms of overall capability and future expansion. As a simple rule, always plan for higher performance relative to connector
THE REPAIRABILITY FEATURES OF A CONNECTOR ARE EVERY BIT AS IMPORTANT AS THE PERFORMANCE RATINGS.
design. Selecting the best connector on overall performance instead of basic qualifications and lowest price will help ensure readiness to meet future needs.
Visit Carlisle Interconnect Technologies to learn more.
The Octax® Family of connectors provides the widest range of options for size and signal configuration.
Seal-Connect ® FOR UNDERWATER VEHICLE APPLICATIONS
Remotely Operated Vehicles (ROV) and Autonomous Underwater Vehicles (AUV) are vital systems commonly used in subsea applications for the oil and gas, oceanographic research, and military industry. These underwater vehicles must perform in rugged, pressurized environments where uptime and reliability are critical to the operation, with expensive electronic equipment onboard that must be protected. Greene Tweed’s Seal-Connect ® electrical and optical product lines are designed and tested for harsh environments with vast experience in high pressure environments capable of withstanding operating depths over 20,000 ft with pressure ratings ranging from 25,000 - 35,000 psi. Custom Seal-Connect ® products undergo extensive mechanical property lab testing and can perform in harsh media, saltwater conditions.
ST & FC CONNECTOR FAMILY
FIBER OPTIC EXTREME
The FC connectors use a threaded position keyed coupling connection while the ST connectors feature a bayonet twist-lock (j-slot) connection. When used with an FC adapter , ST adapter , or Permanent Bulkhead Feedthrough (PBF) respectively, the result is a hermetically sealed connection protected from wet environments and particulates that can irreversibly degrade optical fiber. The DRY™ HP Series is intended for use in submerged, seawater environments and can withstand pressures up to 10,000 psi*. All FC and ST connectors have passed stringent immersion and heat/humidity tests with minimal light loss.
For harsher environments, Seal-Connect ® Fiber Optic Extreme ® solutions provide an optical feedthrough system that ensures data transmission when exposed to extreme pressures and extreme temperatures – is capable of withstanding operating pressures of 2 0 ,000 psi and temperatures up to 3 02 °F (1 50 °C). This feedthrough can be designed with up to 24 channels. Along with the Seal-Connect portfolio, Fiber Optic Extreme has high durability and consistent performance in tough, saltwater environments.
*Internal lab testing to 5,000 psi with customer field qualification testing to 10,000 psi
Greene Tweed | 1930 Rankin Road | Houston TX 77073 USA | Phone: +1.281.765.4500 | gtweed.com
18 Statements and recommendations in this publication are based on our experience and knowledge of typical applications of this product and shall not constitute a guarantee of performance nor modify or alter our standard warranty applicable to such products. © 2022, Greene Tweed all rights reserved. All trademarks are property of their respective owners.
SHOCK, VIBRATION, AND CORROSION: AVOIDING DAMAGING EFFECTS IN HIGH-PERFORMANCE CONNECTORS JAN HROUDA, INDUSTRY MANAGER, INDUSTRIAL ALEX WROTEN, HIGH SPEED BOARD TO BOARD AND RUGGED/POWER PRODUCT MANAGER MATT BROWN, PRINCIPAL ENGINEER SAMTEC
Industrial applications and emerging automotive designs demand long-life, rugged connectors whose performance tolerates the effects of shock, vibration, and corrosion. Some of these harsh environments also require connectors to withstand multiple mating cycles, which adds more complexities to the selection process. Designers must consider the materials selected in the connector design process to protect against shock, vibration, and corrosion, and weigh the tradeoffs in terms of product lifecycle and cost.
Industrial automation applications, such as flowmeters, controllers, or safety devices, are subject to shock and vibration issues, and they require long life cycles of 10-20 years. As a result, the connectors in these products need to be ruggedized, often including special plating or multi-finger contacts. Any non-sealed component used in a coastal or industrial environment is also subject to accelerated corrosion because of sulfur and other chemicals in the air. Special testing can determine if a connector design is acceptable for
these types of environments. A connector’s plating is a crucial element in long life as well as its ability to handle shock and vibration and resist corrosion. CORROSION Copper will oxidize and create contact resistance, so it needs to be finished with another layer, such as tin, gold, palladium, or silver (for very high temperatures). Tin is inexpensive and highly conductive, but it can be subject to fretting corrosion  and tin whiskers which can lead to dangerous conductivity . Fretting corrosion occurs with vibrations over time. These micro movements can lead to oxidation where the tin is making a connection, and ultimately lead to a failed connection (specifically, an oxide forms, breaks, and then eventually corrodes the connector away). This can be avoided with lubrication, but tin is typically not used on contact points for high-performance connectors.
The next best plating choice is gold, which is one of the best conductors of electricity. It is a soft metal, so it is often hardened into an alloy with an element such as cobalt. Unfortunately, copper can migrate through gold within a year or even months. The industry standard is to use a layer of nickel between the copper and the gold to prevent copper migration. Nickel is desirable because of its resistance to wear and conductivity . To complicate things, harsh or high temperature conditions can speed up the oxidation of copper. This can be addressed with thicker nickel layers or thicker gold layers. Gold plating in the range of 10 micro inches is very porous, and, while it looks continuous, the pores can provide a way for the base metal to oxidize. Increasing the gold thickness to 30-50 micro inches can greatly improve corrosion resistance . For instance, in its Extended Life Product (ELP) version of the Tiger Eye connector, Samtec uses up to 30 micro inches of cobalt gold over a minimum of 50 micro inches of sulfamate nickel over a copper alloy substrate (Figure 1). For any other application, in standard conditions, 10 micro inches of gold would be sufficient. Some new extended life applications are requesting 50 micro inches of gold plating.
DESIGNERS MUST CONSIDER THE
MATERIALS SELECTED IN THE CONNECTOR DESIGN PROCESS TO PROTECT AGAINST SHOCK, VIBRATION, AND CORROSION, AND WEIGH THE TRADEOFFS IN TERMS OF PRODUCT LIFECYCLE AND COST.
Figure 1: Cobalt gold contacts are plated over sulfamate nickel and BeCu in the Samtec Tiger Eye product. This product features three points of contact and is qualified to 2,500 mating cycles .
How can you tell if a material will avoid corrosion and support long-life? Mixed Flowing Gas is an industry standard test to evaluate a product’s resistance to corrosion caused by gases in the atmosphere. In this test, a product is placed in an environmental chamber and subjected to gases found in the atmosphere, such as chlorine, hydrogen sulfide, nitrogen oxides, and sulfur oxides, as well as varying levels of temperature, airflow, and relative humidity . Connectors subjected to this test are then tested for low-level contact resistance. Anywhere there is accelerated corrosion, it will cause an issue on the plated surface. Samtec’s certified Extended Life Products, for instance, are exposed to 10-year Mixed Flowing Gas, where sulfur dioxide, chlorine, hydrogen sulfide, and nitrogen dioxide flow around parts for 14 days and achieve high mating cycles (250 to 2,500) . The de facto industry standard is to use nickel under cobalt-hardened-gold up to 125 °C. Gold alternatives are being looked at for higher temperatures. For instance, palladium nickel has the potential to be used between the copper and gold to increase operating temperatures up to 150 °C. Beyond that, plating choices typically include silver for applications well over 200 °C, such as electric vehicle charging. SHOCK & VIBRATION Numerous outcomes can result when a connector experiences shock and vibration, and a range of tests can be performed to ensure good performance . Perhaps the most common failure is cracked solder joints. When a gold-plated connector is soldered, some gold will migrate into the solder joint. If there is more than 5% gold in the solder
joint, it becomes brittle, and any vibration will cause the solder to shatter. It is imperative that in processes using gold-plated connectors the solder joints are extremely well controlled. One way to minimize the risk is to only put gold on the contact point of the connector. This selective gold plating is shown in Figure 2, where the manufacturer’s plating lines deposit nickel on the entire pin and tail, and then put gold only on the contact point (to provide corrosion resistance). This is also a more cost-effective solution than gold-plating the entire pin and tail of the connector.
MULTIPLE MATING CYCLES Generally speaking, a connector’s mating cycles are determined by the material used for the connector’s contact, plating material, and the plating thickness. ELP connectors made with BeCu contacts and 30 micro inches of gold plating, for instance, can withstand up to 1,000 mating cycles, while inexpensive pins made with tin plating over copper will typically tolerate up to 15 mating cycles. Figure 2: Selective gold plating of just the contact point, which improves the connector’s performance in the presence of shock and vibration, shown on a Samtec HSEC8-DP Series.
Connector manufacturers can develop test plans to qualify extended life products. Samtec, for example, qualifies its ELP using ECIA-EIA-364-G, the “Electrical Connector/Socket Test Procedures Including Environmental Classifications” standard, and publishes its test results in the documentation section of the Samtec website. FUTURE WORK There is still more to be learned to increase mating cycles and improve resistance to corrosion
. Work in materials science and mechanical engineering is ongoing in these areas, with efforts underway to increase the hardness of the nickel alloy and to experiment with different plating thicknesses and materials.
Visit Samtec to learn more.
References:  Fretting Over Fretting Corrosion , Samtec Blog, 2017.
 Wishart, Laura. DETAILED DISCUSSION OF MIL-STD-1353 (PART 1): TIN PLATING . Lectromec white paper.  Wishart, Laura. DETAILED DISCUSSION OF MIL-STD-1353 (PART 2): NICKEL AND GOLD PLATING . Lectromec white paper.  Gold Plating Thickness of Connectors - Advanced Plating Tech blog.  TFM/SFM - Extended Life Testing (2500 Cycles) Report, Samtec website, 2017.  Mixed Flowing Gas Testing Introduction and CALCE MFG Capability, CALCE Research Center, University of Maryland white paper.  Samtec Product Testing Guide  Scopelliti, Dave. Shaken Not Stirred: Vibration Testing Explained . Samtec website, 2020.  Boesing, Danny. Connector Plating FAQs: What’s New, Shelf Life, Corrosion, Solder Wicking , Samtec website 2022.
INTERCONNECTS ADDRESS SPECIFIC HARSH ENVIRONMENT NEEDS
CONSIDERATIONS FOR D-SUBMINIATURE CONNECTORS USED IN HARSH ENVIRONMENTS AND REMOTE LOCATIONS
MARCO LAMANNA SENIOR DIGITAL MARKETING SPECIALIST EDAC INC.
Providing a highly durable D-subminiature (D-sub) connector with appropriate retention and a high-reliability connection is essential for harsh environments and remote locations.
Harsh or rugged environments pose multiple challenges for connectors, with some of the most common being temperature extremes, contaminant exposure, corrosive liquid and gas exposure, radiation exposure, electromagnetic interference (EMI), pressure, and vibration. Each of these challenges can be addressed with a durable D-sub connector. The following connector considerations provide information to help prevent malfunctions in the field related to these challenges. INGRESS PROTECTION (IP) Ingress Protection or IP rating is an international standard providing requirements to protect against dust and water exposure.
EDAC’s 627WC Series Waterproof Power Combo D-Sub Connector Assemblies are highly reliable and come in multiple configurations for harsh environment or remote location applications.
CORROSION PROTECTION Corrosion protection is mainly a function of the material used for the manufacture of the connector or the backshell in a shielded system. Specialized plastics or metal shielding (usually stainless steel or aluminum) are available and capable of withstanding corrosion. OPERATING TEMPERATURE Some applications must operate in temperature ranges of extreme cold or extreme heat, making the materials used for the connectors a primary consideration. The following results, which are not all-inclusive, could occur if the incorrect material is used in manufacturing the D-sub.
Exploded view of Waterproof Power Combo D-Sub Connector Assembly emphasizing some waterproofing subcomponents.
Contaminant exposure requires a minimum IP rating of IP50 for dust or IP67 for water ingress. To address continuous water exposure including higher-pressure applications, an increase to IP68/69 for D-sub connector options is recommended.
Melting . Housing and contact materials can
melt if they are not designed to withstand high- temperature operating environments.
from the contact or terminal, the mounting hardware, and the backshell used on and in the D-sub connector assembly.
Expansion. Using set material that does not expand is a best practice. Still, consider that some materials expand with heat exposure. This can result in additional stress on the connection and create continuity issues if the expanding material interferes with the contacts. Contraction. Some materials contract with cold exposure, possibly resulting in additional stress on the connection and creating continuity issues if the contracting material interferes with the contacts. CONTACT TYPE AND SIZE The contact type and size should be considered in applications with higher amperage requirements. In general, the bigger the contact or terminal, the higher the amperage it can withstand. Waterproof Power Combo D-Sub Connectors use power or coaxial contacts solely or in combination with signal contacts. They provide an IP67 rating and up to 40A of power for applications that require higher amperage. RETENTION Retention helps the connector address pressure and vibration challenges. This retention is primarily EDAC’s 627WC Series Waterproof Power Combo D-Sub Connector Power and Signal Contacts Shown here: Power - 40A (left) and Signal - 5A. Other contacts, such as coaxial, are also available.
Exploded view of Waterproof Power Combo D-Sub Connector Assembly emphasizing some retention points.
Additional retention could be built into the D-sub through polarization manufacturing capabilities, directly impacting the insertion and withdrawal forces used when connecting the connector. Each retention mechanism contributes to the prevention of disconnect or damage in the D-sub connector system, ultimately providing the highly reliable and consistent continuity expected in harsh environment and remote location applications. SHIELDING D-sub connector shielding provides increased retention, as discussed above, and can also provide EMI protection if the correct materials are used. D-sub backshells that use specific materials work well to help prevent full exposure to electromagnetic interference (EMI). If the D-subminiature connector is part of a cable assembly, it should be paired with braided cables to increase protection against EMI. For applications that require the highest EMI protection, D-sub connector assemblies designed to MIL-STD 461 and MIL-STD 464 standards should be considered.
MATING CYCLES The harshest environment or remote location applications do not usually require many connection cycles, but they should still be considered. The number of cycles, or the number of times expected to reconnect a connector in the application, is primarily determined by the contact plating as this plating, usually gold, wears over time with use. Another consideration for mating cycles is the spring force on the contact, if applicable. D-sub connector applications with low cycle expectations could use a gold flash option whereas an application with high cycle expectations would
require an increased plating thickness to ensure a longer useful life.
Ultimately, when designing for harsh environments and remote locations, the best course is to determine the application challenges before deciding which D-sub connector assembly to use. This will avoid overbuilding a D-sub connector assembly and unnecessarily increasing costs. For design suggestions and additional considerations for unpredictable weather conditions in a harsh environment or remote location, contact a highly experienced manufacturing engineering team.
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PRESS-FIT TECHNOLOGY AS A CONNECTIVITY SOLUTION FOR THE HARSHEST ENVIRONMENTS
JOSHUA JACOBI, CHIEF SALES OFFICER MARKETING TEAM EPT USA
vibrations in the harshest environments. As a result, press-fit connections have been used successfully for more than 50 years, primarily in high-performance and safety-related applications such as automatic braking systems, rugged construction equipment, and power-tool applications. WHAT IS PRESS-FIT TECHNOLOGY? Press-fit technology is a solder-free option for making electrical-
Wherever high-stress environmental conditions such as temperature fluctuations, shock, vibration, moisture, dust, and dirt prevail, press- fit technology has proven itself to be a reliable partner. Press-fit technology creates a permanent mechanical and electrically conductive connection between the PCB and connectors. It can be used to create a simultaneous electrical and mechanical connection in just one process step. What’s more, press-fit contacts offer significantly greater power transfer than solder contacts
mechanical connections. The pins of a press- fit connector are first positioned into their intended location on the plated through-holes of a PCB, where pressure is then applied to the contact. The contact is pressed into the PCB hole using a defined,
thanks to their lower contact resistance of under 1 mW. Press-fit connections can be used at temperatures ranging from -40 °C to +150 °C and can readily withstand
Press-fit contacting can come in a variety of sizes and forms depending on the needs of a given application.
COST AND SPACE-SAVING BENEFITS OF PRESS-FIT During PCB product development, installation space and costs quickly reveal strict limitations. Cost-saving and space-saving solutions become critical to the feasibility of the design for both the product’s performance and long-term manufacturing viability. When installation space is a limited commodity, press-fit technology is an appealing solution. The press-fit mechanism requires only one component, meaning no additional spacers are required for a secure connection. Just one component creates both a mechanical and an electrical connection, not only saving space on the circuit board, but also reducing costs. In a press-fit configuration, cost-efficient components should bring additional functionality as well as conserve resources. Press-fit often offers the best possible benefit-cost ratio of an assembly – with press-fit connections, component processing is fast and simple. Printed circuit boards can successfully be electrically and mechanically connected with only a single-step process, while
controlled force that allows for consistent quality and fast, problem-free processing. In order to accomplish a connection between the pin and the board, the pins of the press-fit system have to be slightly larger than the diameter of the metalized hole in the PCB. The holes in the PCB wall should only deform minimally, while the flexible interior of the connector’s terminals absorb the force and deforms at a specifically engineered point. This results in a cold welding connection between the press-fit pin and PCB hole. Cold welding joins the outer metal atoms of the PCB hole and press-fit pin, creating a stable atomic lattice that allows electricity to pass through. This type of connection comes very close to thermal welding, but with the added benefit of not introducing any heat that could potentially cause damage to the PCB or any neighboring electronics. By using only force, press-fit technology provides a connection that eliminates the need for high heat. Press-fit also offers minimal deformation of the hole wall. The final result is a gas-tight and mechanically resilient connection that conducts electricity with great reliability, even in demanding electrical environments.
The key components of a press-fit connection
avoiding the need for complex soldering work or expensive cable solutions.
Press-fit is also capable of withstanding the high heat buildup present in environmentally difficult applications, such as automotive engines and high-speed computing servers. The technology outperforms comparable soldered connections with its higher temperature tolerance. The durability of a connector is usually defined by the number of connection cycles it can complete without any reduction in the quality of transmission. The most important factor affecting the number of connection cycles is the quality of the plating. High-quality, durable contact coatings reduce the frictional wear on the surface during the connection procedure. Press-fit terminations can support a wide variety of plating types, based on the demands of the application. A reliable partner for the most demanding applications, press-fit is an excellent solution where temperature fluctuations, shock, vibrations, moisture, dust, and dirt play a major role. Despite a history of over 50 years of use, press-fit remains relevant in the modern day due to its unparalleled cost-saving and space-saving benefits, while offering a rugged, permanent mechanical and electrically conductive connection between the circuit board and the connector.
RESILIENCE IN THE MOST DEMANDING CONDITIONS AND HARSH ENVIRONMENTS A tried-and-true press-fit connection also enables high switching currents. Since no contact transition limits the current-carrying capacity, press-fit can withstand continuous high current as well as tolerating sudden current spikes. This current carrying capability is excellent for high-demand power applications such as climate controls, power tools, agriculture equipment, military and aerospace applications, and manufacturing, medical, and automotive technologies. It also works well for applications that experience high impact from the operating environment, such as temperature fluctuations or vibration.
Press-fit contacting is suitable for high-current applications, despite the demands of high-stress mechanical loads
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FIBER OPTICS: THE MOST EFFICIENT WAY TO TRANSPORT DATA, EVEN IN HARSH ENVIRONMENTS KEVIN HAMILTON DIRECTOR OF BUSINESS DEVELOPMENT POWELL ELECTRONICS
Fiber optic cables carry many times more data than is feasible over copper-based connectivity. This increased bandwidth is necessary for the highest definition video and other data intensive purposes, but the fact that optical signals travel at close to the speed of light is also vitally important. This makes near real-time data latency feedback requirements a reality. When attempting to target
an inbound hypersonic missile, microseconds count, and optical cable is 99% faster than copper. Latency times and reliability are also of paramount importance in emerging applications such as autonomous driving or drone deliveries.
Fiber optics has other inherent benefits as well. It conducts no electricity and is completely immune
to electromagnetic interference (EMI), generates no heat throughout the cable, and signals cannot be poached off fiber optics as they can easily be done in copper-based systems. Also, fiber optics is future- proof. The physics of light do not change, so the fiber optics being used today will essentially be the same a hundred years from now. Additionally, fiber optics has a fraction of the weight of copper. This is crucially important for aerospace applications where engineers work for days simply to save a pound of mass. All these favorable attributes are readily acknowledged; however, there remains a bias against using fiber optics in harsh environments. Most of our everyday lives are not lived in such settings; our homes and offices are protected places where less vigorous equipment is used. Nevertheless, there are many applications where electronic equipment is exposed to more robust conditions that include temperature extremes, physical shock, high vibrations, intense electrical interference, atmospheric pressure fluctuations, water immersion, corrosive chemical exposure and many other harsh conditions that have the potential to disable the system that these electronics are intended to service. Such systems are most vulnerable at the interconnection devices. Fiber optics is the perfect solution for high-reliability, high-performance, and quality signal integrity in extreme environments like agriculture, mil/aero, and space applications, where space and weight is limited. At first glance, fiber optics may seem unsuitable for such applications. After all, a single mode optical fiber is just 9 micrometers (microns) of glass that is cladded (essentially insulated) up to 125 microns and then protected with a similar sized coating, typically up to 250 microns. For comparison’s sake, a human hair is
Fiber optics is the perfect solution for high-reliability, high-performance, and quality signal integrity in extreme environments like agriculture, mil/aero, and space applications, where space and weight is limited.
nominally 70 microns in diameter. The common thinking is that optical fibers are delicate pieces of glass that are only suitable for use in conduit or a similarly protected location, but such beliefs need to be dispelled. Another favorable attribute of fiber optics is that it employs all the same connector standards as copper, with all the noted protections, while providing for commonality among components. Engineers know these standards well and are familiar with navigating and specifying them. They include military specifications such MIL-DTL-38999 (D38999), ARINC, and the newer Sensor Open Systems Architecture (SOSA) connector standards.
are used in everyday enterprise and datacom applications, but Amphenol’s version illustrates how it can be protected with the workhorse of harsh environment data connectors. The D38999 connector can even house the transmitter and receiver equipment needed for optical fiber signals. This is a harsh environment connector and signal converter in one housing, which component engineers have been specifying and using for generations. However, a potentially unfavorable reality about fiber optics is that it is indeed more difficult to terminate than its copper cousins. For low-voltage copper, a simple metal to metal linking without regard to orientation is all that is required. For the seamless transference of a light wave, those connections must be made flush at the ends of each fiber optic side without contamination, clouding, or cracking of each surface. This requires a more refined set of skills and knowledge than most technicians who work with copper possess. Accordingly, fiber optics are more often provided as pre-terminated assemblies by optical experts. It is crucial to work with a distributor that will provide product and application expertise, ideally at the earliest developmental stage, to specify
LC Field Fiber Optic Connector
In fact, the D38999 standard is used to protect the very common LC fiber optic connection method by Amphenol FSI (displayed above). LC connectors
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