Customized Interconnects For Harsh Environments
By Arthur Visser, Bishop & Associates Inc.
Contributions from Hypertac and Radiall

During the past couple of months, most of our readers in the northern hemisphere, from North America to Europe to Russia, China, and Japan, have experienced severe winter conditions. In some places, this winter weather has been out-of-the-ordinary, with record snowfalls and blizzard conditions that have disrupted traffic, public transport, and air traffic.

Although the average individual does not always realize this, interconnects used in a wide range of applications, ranging from rolling stock to aircraft and automobiles to infrastructure equipment, energy generation, and other “critical” equipment, have to continue to perform according to specifications without failure, even in the most severe and harsh conditions.

Planes need to be able to take off, trains need to bring commuters to work, and cars should not conk out during your travels. 

Connectors Under Pressure
An electric/electronic connector is a critical component in the aerospace market due to its impact on:

• Signal/power integrity and stability

• Traveller’s safety

• Travel quality (entertainment)

The critical electro-mechanical factors to be considered in a harsh external environment include heat, cold, wet, ice, dust, storms, human factors, and mechanical challenges, such as shock and vibration.

These issues must be addressed by using a rugged connection to protect against mechanical and environmental disturbances. It is necessary to identify such applications and distinguish them from “normal indoor applications.” Harsh environment connectors may operate in the following conditions: 

• High or low temperatures

• Vibrations

• Electromagnetic radiation

• High voltage/current, often combined with other extremities

• Physical abuse by users, accidental disturbance, other hardware, etc.

• Shock

• Mechanical forces applied to the connection (pulling, pushing, hitting, etc.)

• Precipitation (rain, snow)

• Humidity, fog, and other environmental factors that create an excessively moist or dry atmosphere

• Exposure to chemicals, oils, or other substances

• Corrosion or abrasion (seawater, sand)

• Pressure (sub sea)

In order to counteract these harsh conditions, a good knowledge of the application is necessary to design the appropriate connector. This knowledge will impact the final selection of the connector:

• Material and plating (chemical composition and appropriate plating)

• Contact technology (able to resist vibration, to carry high current)

• Sealing device

• Physical dimensions and shape to be mechanically resistant

Connector manufacturers play an important role in developing and designing interconnect products that can perform their task in such harsh conditions, and some companies have specialized in these high-reliability connectors. Hypertac (Smiths Group plc) and Radiall are two connector manufacturers whose expertise and products are important to this market. They have carved out a market for specialized, custom-build interconnects and have built their company growth strategy on these markets. Let’s take a closer look at some of the products these companies have designed and see what is special about them, especially in the military and aircraft applications.

Hypertac

Hypertac is a supplier of high-performance electrical connectors and interconnect solutions for the most demanding of applications, ranging from satellites and next-generation fighter jets to life-saving defibrillators.

It is clear that this type of equipment requires superior quality products offering great performance and optimal reliability. Hypertac tackled these requirements with the launch of the Hypertac hyperboloid contact technology, widely acknowledged as an extremely reliable and versatile contact.

Hyperboloid Contact Technology
The Hyperboloid© socket has a number of spring wires, the position of which is defined by a wire carrier. This is fitted to an outer sleeve or shank that carries the termination of the socket. The spring wires within the socket are set at a small angle to the center line and are deflected when the mating pin contact enters. Each spring wire is deflected within its elastic limit and makes a line contact with the pin. A smooth wiping action reduces wear of the plating surfaces of the pin and socket wires. This construction allows a very tight control of the spring forces, and hence, the insertion and withdrawal forces. The Hypertac Hyperboloid contact design ensures good technical performance, including:

• Multiple-line contacts of low resistance maintained under high levels of shock and vibration

• Low insertion forces

• Low wear of plating surfaces for long life

• Uniform electrical and mechanical characteristics over a high number of mating operations (up to 100,000)

• High current rating

The Hypertac Hyperboloid contact may provide the users with additional commercial benefits, such as:

• Relatively low cost of ownership; the contact does not need replacement during equipment life

• Reduced system costs; equipment design is less critical (e.g. shock and vibration resistance)

• Reduced qualification costs; no re-testing required due to contact failures

Hypertac contacts offer pin dimensions from 0.3mm in diameter for signal contacts to 28mm for high currents, various termination types (crimp, solder cup, DIP straight, or SMT), and pin finish or coating. The contact itself is enclosed in a housing that can be PCB-mounted, D-shaped, rectangular, rack-and-panel, circular, or customer-defined.

Application-Specific Engineering
A quick glance at the catalog of global interconnection suppliers and electronics distributors reveals such a huge variety of standard products that the use of a custom solution might seem unnecessary. And yet, a company such as Hypertac continues to find success with their custom interconnection products. More than 75 percent of its revenues are from custom-designed products and 30 percent of its annual turnover is achieved through sales of new products. It is clear that, although Hypertac offers a wide of range of standard products, a more substantial part of its business is centered on custom-build interconnect solutions, including single specialist contacts, through to connectors, cable harnessing, and even complete sub-systems designed and tested in-house. This allows Hypertac to continue developing its engineering expertise.

To understand why custom products continue to be such an important part of the interconnection market, it is necessary to know the reasons why customers turn to these solutions.

The first motivation is often to simplify the overall system design. For instance, in some situations, the connector must achieve an unusual number of connections, fit within a given size and shape, or accommodate design changes in PCBs or other interconnections. Often custom solutions are the only way to achieve the required performance. This becomes even more obvious if the interconnection in question is a weak point in the design and a standard product cannot guarantee signal continuity while subjected to shock, vibration, and corrosion.

Custom solutions also meet the need to achieve high quality levels that conform to industry standards and/or to apply for certification. A customer may also be looking for exceptional performance to produce an end-product with a unique or exceptional competitive advantage.

The success of a custom connector does not rely only on its core technology. Other criteria in serving the custom-build market for interconnects is the capacity for rapid prototyping or to validate solutions with laboratory tests, in-depth knowledge of materials and production tooling, and the ability to launch pre-production with short lead-times. The key factor is the close relationship and confidence between supplier and customer, starting at the first sales meeting and continuing to develop the technical co-operation required for real collaborative product design.

It is not surprising that Hypertac’s culture considers not only unit costs, but cost-of-ownership, to encourage designers to fully realize the benefits of custom-build products, even if a premium is attached to the unit price for a comparable standard product. Hypertac’s steady growth confirms that the company is successful with this strategy. Technical expertise is at the core of this strategy and is combined with local development capacity and a central coordination.

New Developments
Hypertac’s HyperSpring^® product combines the high reliability Hyperboloid© contact technology with the mechanical features of a spring-loaded contact to produce interconnections with improved signal integrity, high reliability, current density, and proven stability over time. The key innovation in a HyperSpring^® connector is that the spring itself is not used for electrical conduction. The electrical conduct is a socket placed between the barrel and the plunger of a common spring-loaded contact. This means that the material used to form the spring may be chosen solely on the basis of its mechanical properties—primarily its elasticity. As a consequence, it is possible to optimize the physical performance of the overall system, achieving a higher number of mating operations than would otherwise be possible.

Separating the spring from the electrical conductor results in a range of advantages, starting with the elimination of a source of problems during testing and measurement—more specifically, the adverse effect on the validity of the measured value in standard spring-loaded contacts using elastic materials that are not exactly ideal for conducting electricity. This problem is magnified when dealing with short measurement intervals. When the spring also serves a conductor in standard spring-loaded contacts, the spring disturbs measurements, especially at high frequencies, introducing a solenoid effect, with the various electrical values varying according to the continual changes in the geometry of the spring itself.

Another advantage of the HyperSpring® is its suitability for use in measurements where, when using the same contact dimensions compared to traditional spring-loaded contacts, higher currents can be reached with a lower ohmic resistance.

This new design can be used for signal, power, and coaxial contacts, and its highly adaptable qualities make it suitable for a large range of uses.

Hypertac has already placed its HyperSpring^® products in various end-user markets, such as test and measurement, automotive, military, and medical equipment.

High-Speed Contact
Hypertac's rugged contact system is designed especially for the transmission of Ethernet high-speed signals in harsh environment applications. The contact uses the Hypertac hyperboloid technology, which guarantees an excellent signal integrity and high reliability, even under high levels of shock and vibrations.

In addition, the high-speed contact system is housed in a robust shell, which enables reliable cabling. The Hypertac contact system is available in twinax, triax, and quadrax versions.

The Hypertac high-speed contact system meets the requirements of Ethernet Class F (CAT 7). It is compliant with the latest Ethernet standards (IEE802.3) and achieves frequencies over 1.2 GHZ.

Radiall

Radiall is a manufacturer of power, data, radio frequency, and fiber optic interconnect solutions. Radiall’s success in the market is based on its ability to understand the specific requirements of its customers and make recommendations and/or develop solutions that meet those requirements, while focusing on a realistic cost-performance balance.

Today, systems are quickly evolving towards more capacity (higher bandwidth, data rate, and frequency) while being used in harsher environments. This trend is a unique opportunity for companies such as Radiall to offer new concepts and solutions.

Complex systems, such as radars, require interconnect solutions capable of handling higher frequencies in a variety of demanding environments, ranging from fighter jets and UAVs to ships and ground vehicles. Radiall’s expertise in RF and fiber optics has allowed them to develop end-to-end solutions for these complex systems in any type of environment.

For RF signal applications, connectors need to be higher in density and frequency, and be designed to fit in smaller packaging, and in some cases, to provide hermetic features, and in other situations, to be resistant to high levels of shock and vibration. Phase-matched RF cables must be stable over a large temperature range, have less weight for airborne applications, and be smaller for ease of integration.

One example of these developments is Radiall’s QRE coaxial connector, developed for an Airborne Early Warning and Surveillance Radar.

As the resolution of electronically scanned radars increase with dimension constraints typical of an airplane, it results in higher density for the interconnection back panel. On previous radar systems, SMA connectors were used. Since the customer also preferred a quick-lock system similar to the one used in Radiall’s QMA connectors, Radiall engineers developed a connector combining the performance and mechanical strength of SMA connectors, with the advantages of a quick-lock connector. The QRE emerged as the solution. The connector is made of high-grade stainless steel, which offers better corrosion resistance than standard stainless steel. Sealing O-rings are made of blue fluoro-silicone, resistant to most contaminants, including oil, aviation gasoline, de-icing fluids, and others.

The quick-lock mechanism allows the operator to quickly connect a QRE plug on a dense patch panel, without a tool, and without a trade off on the retention force. The challenge was to design a connector that would be easy to connect, yet difficult to disconnect. The 34-lb. minimum retention force of the QRE guarantees no electrical discontinuity during severe vibration and shock conditions. As a result, the installation time of cable assemblies on the radar was greatly reduced due to the switch from SMA to QRE.

Multi-signal interconnects combining RF and data are also needed to quickly assemble and disassemble systems and units, while withstanding the most demanding constraints of each platform.

A complete range of fiber optic interconnects based on the LuxCis® concept has been developed for the new radar architecture that uses RF-over-fiber transmissions. Offering the best optical performance, such as low return loss, the connectors’ form, fit, and function are optimized for each type of environment. It can be rectangular for the highest density requirements, circular for the quickest maneuver requirements, and sealed or even hermetic for special condition environments.

Beyond the physical link, Radiall is also capable of supporting customers at the system level and signal generation stage. One example is the D-Lightsys transceiver product range. These fiber optic transceivers are specially designed to operate under harsh environmental conditions while providing high data rates and a large budget link. Due to their compact design, these products have outstanding mechanical resistance to shock and vibration, and they can withstand an extended temperature range. Modules are sealed for protection against the environment and are available in a hermetically sealed version for space applications. Designing for harsh environments does not mean compromising performance.

D-Lightsys transceivers can deliver data rates of up to 10 Gb/s per channel, offer very low consumption, and present the smallest package available in the industry for this type of product. Designing for harsh environments does not mean compromising performance.

Quest for Growth
Bishop & Associates estimates that the global market for application-specific connectors was worth nearly $5.5 billion in 2009. This number includes application-specific connectors for “normal” indoor applications. The share of application-specific connectors of the total connector market varies between 15.5 and 19.5 percent of the total global connector market, which is indeed a substantial piece of the market. It is not likely that this market will shrink in the future due to the continuous demand for specific interconnect solutions for a range of applications adapted to unique technical constraints or environmental conditions. However, the market for application-specific connectors has also suffered from the global crisis: It decreased by more than 30 percent in 2009. How quickly this market will recover is yet to be seen, but it looks like we’re off to a good start for 2010. 

                      $ millions

For more information, visit:
www.hypertac.com or www.hypertronics.com
www.radiall.com

Arthur Visser
Managing Director—Europe, Bishop & Associates Inc.
Arthur Visser started his career in 1987 at Océ Corporate headquarters in Venlo, the Netherlands, as a product engineer assigned to provide support to the American Océ organization. In 1988, he joined OMRON Corporation at its European headquarters in the Netherlands as the European product manager responsible for industrial automation systems and components. In 1993, Arthur moved to OMRON Electronics in Brussels as a key account sales engineer, and in 1995 became the product and marketing director. In 1998, he joined the connector manufacturer HARTING as managing director for its Belgian subsidiary. Arthur became an independent consultant, based in Brussels, in 2003.

Arthur has a bachelor of science degree in airplane engineering, degrees in marketing and finance, and a master’s degree in e-media enterprising. His native tongue is Dutch, but he also speaks English, French, German, and Russian.