Guide to Selection and Application of High-Reliability Connectors for SWaP-C

Designers of systems for defense and aerospace applications face increasingly stringent requirements for size, weight, power, and cost (SWaP-C) optimization. As their designs become more complex and compact, they must balance these requirements with high performance and reliability. Traditional connectors often struggle to meet these conflicting demands, challenging designers to find alternatives to meet system design and performance requirements.

This article explores how advanced connector technologies designed explicitly for SWaP-C can address defense and aerospace applications' unique needs. It then introduces high-reliability solutions from Harwin and shows how they are applied in various defense and aerospace scenarios to achieve reliable SWaP-C performance.

The factors driving connector miniaturization

From submarine-periscope systems upgrading to multi-spectral imaging to unmanned aerial vehicles (UAVs) carrying expanding arrays of sensors, the requirements for sophisticated electronics in confined spaces grow more complex each year. Minimizing component size allows additional sensors and other features to enhance system capabilities and improve aerodynamic performance.

Connectors, traditionally among the bulkier components, are critical to successful miniaturization. Reducing connector size requires shrinking contact pitches and lowering weight while maintaining durability and ensuring consistent electrical performance under extreme conditions.

Harwin has responded to these challenges with comprehensive connector families designed specifically for SWaP-C optimization. Their approach centers on three key design principles:

1. Shrinking pitch sizes down to as little as 1.25 millimeters (mm) while maintaining high current-carrying capacity
2. Using multi-finger beryllium copper contacts for signal integrity under extreme conditions
3. Employing high-temperature thermoplastic housings with selective use of lightweight metals for durability

This design philosophy extends across their high-reliability product families, from high-density signal connectors to mixed-technology and high-power solutions.

The impact of connector weight reduction on mobility and efficiency

Weight reduction is crucial in SWaP-C optimization, particularly for airborne and mobile applications. Lighter components can improve flight duration and maneuverability while enabling more equipment to be carried.

Modern micro-miniature connectors can significantly reduce weight compared to traditional industrial connectors through strategic material selection. For example, glass-filled high-temperature thermoplastics can be used for primary housings. At the same time, designers can selectively employ lightweight aluminum alloys only where metal is required for electromagnetic interference (EMI) and radio frequency interference (RFI) protection and mechanical durability.

Even in high-current applications where traditional designs rely heavily on metal components, these material combinations can maintain robust electrical and mechanical performance while minimizing connector mass.

Managing connector costs without sacrificing reliability

In SWaP-C designs, balancing cost reduction and high reliability presents an ongoing challenge for designers of mission-critical systems. For connectors, this means selecting designs and materials that ensure long-term durability with minimal cost.

A key strategy for managing costs is focusing on the total cost of ownership rather than just the upfront component price. While high-reliability connectors may have higher initial costs, their extended lifespan and reduced maintenance requirements can yield significant long-term savings. This is particularly valuable in applications where connectors must endure extreme conditions, including high vibration, temperature fluctuations, and repeated mating cycles.

Furthermore, standardized and modular connector designs can reduce production and maintenance costs through easier integration and replacement. Connectors that meet common industry standards enable interchangeability and streamlined inventory management, reducing expenses over the product lifecycle.

Balancing power delivery with size

Connectors also play a crucial role in power management. The challenge lies in developing connectors that can handle significant power loads while maintaining a compact form factor and ensuring minimal power loss. High-reliability connectors must support efficient power transfer, minimize heat generation, and prevent electrical arcing, all while meeting the modern system design’s space and weight constraints.

Achieving efficiency and reliability requires materials and contact designs that provide low resistance. Connectors featuring robust contact plating, advanced insulation, and optimized contact geometry can deliver stable power even under extreme operational conditions.

A key consideration is combining signal and power connections in a single, compact connector. While integrating signal and power lines reduces the overall connector footprint and frees up valuable space, it also creates challenges in managing potential interference between power and signal pathways.

Application example: jet fighter aircraft cockpits

Examining typical use cases helps to illustrate how these design principles play out in practice. For example, lighting control units (LCUs) in jet fighter aircraft require reliable connectors to manage illumination across different flight conditions and missions. These systems control cockpit, exterior, night vision, and emergency lighting, which demand components that can provide variable lighting intensities within tightly packed environments. The LCU’s limited space requires low-profile components that integrate effectively without compromising performance.

With a pitch of 1.25 mm, Harwin’s Gecko SL connectors offer a compact and lightweight solution that can be 75% lighter and 45% smaller than Micro-D connectors. This makes them particularly well-suited for dense environments like LCUs. Key features of the Gecko SL family include:

• 2.8 amperes (A) per contact in isolation and 2.0 A on all contacts simultaneously
• Four-finger beryllium copper contact design for high reliability
• Moldings made of glass-filled thermoplastic UL94V-0 (halogen and red phosphorus-free)

The G125-MC10605M1-0150L variant features a six-position plug terminating in individual wire leads (Figure 1). A wide range of other assembly styles are available, along with lightweight aluminum hoods that deliver enhanced electrical continuity, cable protection, and effective EMI/RFI shielding.

Figure 1: The Gecko SL connectors are helpful for space-constrained environments such as jet aircraft cockpits. The G125-MC10605M1-0150L variant features a six-position plug terminating in individual wire leads. (Image source: Harwin)

Beyond their compact size, Gecko SL connectors are exceptionally rugged. They withstand shock of up to 100 g for 6 milliseconds (ms) and vibration to 20 g for 6 hours, making them ideal for aerospace environments. With a durability rating of 1000 mating cycles, these connectors ensure reliability through repeated connections and disconnections, a common requirement in maintenance-intensive applications.

Application example: mixed-signal UAV connectors

As another example, UAVs operating in defense environments require rugged and compact connectors that maintain functionality under harsh conditions. These vehicles experience significant vibrations and shocks, making signal integrity crucial for their onboard systems.

Datamate Mix-Tek connectors from Harwin address these challenges by integrating power and signal lines in one compact package. This space-efficient design features a 2 mm pitch that allows ample room on the printed circuit board (pc board) for additional components, ultimately enhancing UAV capabilities and performance. These connectors minimize power and signal loss through low contact resistance values of 6 milliohms (mΩ) for signal contacts and 25 mΩ for power contacts. Rated for 500 mating cycles, they ensure durability in applications requiring frequent maintenance and reconnections.

An example is the M80-5T10805M1-02-331-00-000, which combines two power contacts handling 20 A each with eight signal contacts rated for 3 A each (Figure 2). This configuration supports the power requirements of critical systems and the data needs of control and communication in most UAV applications.

Figure 2: The M80-5T10805M1-02-331-00-000 connector combines two power and eight signal contacts with a pitch of 2 mm into a single housing for space-constrained applications such as UAVs. (Image source: Harwin)

Application example: high-power UAV batteries

Defense-focused UAVs often require substantial power, operating from battery systems delivering tens to hundreds of kilowatts. The connectors linking these batteries to critical components, such as motors, must handle high currents reliably while minimizing power loss.

Harwin’s Kona high-reliability connectors meet these demands by handling 60 A and 3000 volts per contact. Their 8.50 mm pitch supports significant power loads while maintaining defense-grade robustness. A contact resistance of 2 mΩ ensures minimal power losses.

A good example is the KA1-MV10205M1 (Figure 3), which features two male contact pins for a combined maximum current capacity of 120 A. This connector is well-suited to UAV battery connects that need robust power delivery while meeting SWaP-C requirements.

Figure 3: The KA1-MV10205M1 connectors are rated at 60 A and 3000 volts per contact and use a six-finger contact design for stability under high-shock conditions. (Image source: Harwin)

The Kona connectors use beryllium-copper contacts with gold plating, feature a six-finger contact design for stable connections under high-shock conditions, and have a pitch of 8.5 mm. Aluminum alloy backshells and stainless-steel screw locks provide a lightweight and durable design.

Conclusion

Selecting a suitable connector is crucial for balancing the diverse requirements of SWaP-C optimization. Harwin’s advanced connector solutions demonstrate that combining compactness, lightweight design, power efficiency, and durability is possible, enabling designers to meet the complex demands of aerospace and defense applications.