Military Embedded Systems

PRODUCT OF THE WEEK: Omnetics Bi-Lobe and MIL-STD 32139 Nano-D Connectors

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September 11, 2023

This week’s product, the Omnetics Nano-D Bi-Lobe and MIL-STD 32139 connectors, meet stringent size, weight, and power (SWaP) requirements for ruggedized miniature electronic solutions. The devices are suited for applications with extreme signal-integrity and harsh-environment specifications, such as radar, weapons systems, communications gear, satellites, instrumentation, avionics, and more.

Miniaturization Demand

Improvements in chip technology have impacted circuit board designs as well as connector and cable interconnections, leading to demands for greater miniaturization at lower voltages and current levels.

The family of Nano-D connectors meets this need, as each connector is designed to perform at military specification levels for high-reliability and extreme environments. Most Nano-D connectors evolved from the older Micro-D and follow similar specifications.

Smaller and better nano-connector designs often use a 17,200 ksi beryllium copper “spring pin-to-solid-socket” design to insure signal integrity during use. As speeds go up, the wavelength of each signal is shorter; at lower voltages, vibration and circuit noise could confuse the signal. Nano-D connector resistance is kept as low as 12 to 15 milliohms with a capacitance of 2.0 pf to 2.4 pf. Since most circuits have low current flow and low voltage, this is an ideal fit. With increasing speeds, capacitive coupling is also controlled by adjusting the nano-connector insulator spacing to match the specific needs of the application. Low-skew cable technology is also evolving to match the cable performance to the needs of higher switching and signal speed interconnects.

Flex-Pin Design

Omnetics’ Flex Pin contact design predates the advent of the MIL-DTL-32139 nano-miniature specification, and today all MIL-DTL-32139 sockets mate properly with the Flex Pin. The one-piece unit is stamped from ASTM B194 beryllium copper (BeCu) to deliver high conductivity, low interference, and high resiliency. Its excellent spring properties enable it to withstand shock, vibration, and other rugged conditions and it easily passes military specification requirements.

Many high-reliability applications have scaled down to meet SWaP goals, and the Flex Pin has evolved as well: Omnetics reengineered the Flex Pin to improve the design’s performance in the smaller Bi-Lobe package sizes. The Nano Flex Pin features a one-piece design that eliminates the extra crimp welds seen in many overly complex twist pins. Eliminating these excess resistance points helps ensure strength and reliability at every scale.

Family Member Examples

Omnetics Bi-Lobe and MIL-DTL-32139 series of Nano-D connectors are precision-engineered to meet or exceed MIL-DTL-32139 specifications. These nano-miniature connectors feature tightly-packed contacts with centerlines of 0.025” (.64mm).

Single Row Nano-D connectors offer an extremely rugged low-profile connector which meets or exceeds MIL-DTL-32139 requirements. The ultra-miniature nano connectors are available in a range from SMT for printed circuit board surface mounting to straight tails and wired cable.  Designers use these nano connectors for rugged portable applications in the miniaturization of space satellites and robots and in the aerospace, military, geophysical, and medical markets.

Horizontal SMT Bi-Lobe extremely low-profile connectors are well-suited for pick-and-place mounting methods. SMT Bi-Lobe nano connectors feature Omnetics’ highly reliable gold-plated Flex Pin contact system. In addition to ease of assembly, their lightweight construction helps meet size and weight goals. They are rugged and deliver high performance under shock, vibration, temperature extremes, and other rigorous conditions. These connectors are available in a range of options, including mounting holes suitable for PCB and flex mounting. They are available in standard sizes ranging from 9 through 91 positions, as well as custom configurations.

Vertical SMT Bi-Lobe nano connectors require minimal board space on flex circuits and printed circuit boards. These connectors feature Omnetics’ Flex Pin contact system and are available with threaded mounting holes and retention screws. Omnetics’ VerticalSMT Type VV Bi-Lobe nano connectors are available in a wide range of configurations to meet the needs of a variety of critical applications. These connectors are available in standard sizes ranging from 9 through91 positions, as well as custom configurations.

Dual Row Nano-D connectors also meet or exceed the requirements for Mil-DTL-32139.  These rugged high-reliability connectors occupy less space and reduce the weight of the interconnect system for critical miniaturized electronic modules.

Environmental and Harsh Environment Features

  • Shock: 100 Gs when tested for mechanical shock, mated connectors shall not be damaged, and there shall be no loosening of parts. There shall be no interruptions in the circuit which lasts longer than 10 nanoseconds.
  • Vibration: 20 Gs when tested for vibration, mated connectors shall not be damaged, and there shall be no loosening of parts. There shall be no interruptions in the circuit which lasts longer than 10 nanoseconds.
  • Salt Spray (Corrosion): Mated connectors will show no exposure of base metal due to corrosion which will affect performance after be subjected to the salt spray test of EIA-364-26 condition B. Connectors must withstand 48 hours of salt spray. Following the test all connectors shall meet the specified requirements for low-signal level contact resistance and connector mating and unmating forces.
  • Thermal Vacuum Outgassing: These connector assemblies shall have a maximum total mass loss (TML) of 1.0 percent of the original specimen mass, and shall have a maximum volatile condensable material(VCM) content of 0.1 percent of the original specimen mass.
  • Fluid Immersion: Connectors will continue to adhere to the mating force requirements set forth by MIL-DTL-32139 after be subjected to a 20 hour immersion in synthetic lubricating oil, 2 hour immersion in Perchloro ethylene cleaning solvent, and 1 hour immersion in coolant fluid. There will be no degradation of the insulators or encapsulates.
  • Material Fungus Resistance: Materials used in the construction of these connectors are fungus inert in accordance with ASTM G21.
  • Thermal Shock: Connectors will withstand 5 cycles of thermal shock from -55° C to +125 °C per EIA-364-32, condition I. There will be no detrimental damage or degradation of the electrical performance.
  • Humidity: These connectors will meet all the humidity testing requirements in accordance with EIA-364-31, test condition A (excluding steps 7a & 7b). Post humidity, the connectors will pass a 250 VAC DWV test. Within one hour the connectors will pass a 1 megohm insulation resistance test. Following 24 hours, the connectors will pass a 1,000 megohm insulation resistance test.

For more information, visit the company’s website, or follow the links below.


For more information, visit the Nano-D page here, or visit the company’s website, or follow the links below.


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