High-Density Circular Connector Series
Overview
UNICONN high-density circular connectors are engineered for mission-critical applications that require compact size, high reliability, and strong resistance to harsh environments. The series offers multiple shell materials, advanced sealing performance, and flexible contact layouts suitable for aerospace, defense equipment, industrial automation, robotics, and power-distribution systems.
Designed for consistent mechanical stability and long service life, these connectors provide secure locking structures, vibration resistance, low-loss electrical transmission, and a wide selection of plating, insert arrangements, and termination styles to meet diverse system requirements.
Key Features
High Reliability & Secure Locking
Engineered with a durable coupling mechanism that ensures secure locking, stable mating, and long service life in demanding environments.
Superior Vibration & Shock Resistance
Designed to withstand high-level vibration and shock conditions, making it suitable for aerospace, robotics, and mission-critical systems.
Multiple Shell Materials & Plating Options
Available in aluminum alloy, stainless steel, and titanium alloy with various surface finishes to support corrosion resistance and environmental durability.
Flexible Insert & Contact Layouts
Supports a wide range of insert arrangements from miniature signal contacts to high-current or coaxial configurations.
Advanced Environmental Protection
Silicon rubber seal, thermoplastic insulation, and advanced sealing structure offer resistance to moisture, dust, chemicals, and extreme temperatures.
Low Electrical Loss & Strong EMI Protectio
Optimized electrical performance with low contact resistance, high dielectric strength, and optional EMI shielding accessories.
How to Order
Example Ordering Code
UH / 20 W B 35 P N
1 – Series
2 – Shell Type
3 – Finish
4 – Shell Size Code
5 – Insert Arrangement
6 – Contact Style
7 – Keying Position
Series
UH – Uniconn high-density circular connector series
Shell Type
20 – Wall square flange receptacle
24 – Jam-nut receptacle
26 – Straight plug
21 – Square flange gas-sealing receptacle
23 – Jam-nut gas-sealing receptacle
25 – Solder-mount gas-sealing receptacle
27 – In-line solder-mount sealing receptacle
31 – Span-wire separating plug
Finish Options
W – Olive-drab cadmium plating (–65°C ~ +175°C)
F – Chemical nickel plating (–65°C ~ +200°C)
K – Stainless-steel passivation (–65°C ~ +200°C)
S – Stainless-steel nickel plating (–65°C ~ +200°C)
T – Titanium-alloy electroless finish (–65°C ~ +200°C)
Y – Stainless-steel passivation (gas-sealing series)
N – Stainless-steel nickel plating (gas-sealing series)
Shell Size Code
A – 09
B – 11
C – 13
D – 15
E – 17
F – 19
G – 21
H – 23
J – 25
Contact Style
P – Standard crimp pin
S – Standard crimp socket
PH – Solder-cup pin
SH – Solder-cup socket
PC – Short straight pin for PCB termination
SC – Short straight socket for PCB termination
PL – Long straight pin for PCB termination
SL – Long straight socket for PCB termination
A – No pin / Customized pin
B – No socket / Customized socket
X – Pin contact with sealing grommet (sealing type)
Keying Position
N – Normal
A / B / C / D / E – Alternative keying positions to prevent mismating
Technical Specifications
Mechanical Performance
Sinusoidal Vibration
10–500 Hz, speed 254 mm/s
50–240 Hz, double amplitude 1.5 mm
140–2000 Hz, acceleration 58 m/s²
Random Vibration
High temperature: 96 m/s² rms (10–2000 Hz)
Environmental temperature: 480 m/s² (7–300 Hz)
Shock
2940 m/s², 3 ms
Durability
500 mating cycles
(Span-wire Series: 1500 mating cycles)
。
Environmental Performance
Temperature Range
Olive drab cadmium: –65°C ~ +175°C
Nickel plating / Passivation: –65°C ~ +200°C
Salt Spray
W (Olive drab cadmium): 500 hours
F / K / N: 48 hours
Humidity Resistance
10 cycles, 24 h per cycle
Fluid Resistance
Hydraulic oil, refrigerating fluid, 12+ solvents
Sealing (Span-wire Series)
Rainfall speed: ≥ 2 mm/min
Rain drop diameter: 0.5–4.5 mm
Rain duration: 40 minutes
Electrical Performance
Dielectric Strength (Inserted Condition)
Level M – 1000 V
Level N – 1800 V
Level I – 1300 V
Sea Level – 21000 m: 600–800 V
Insulation Resistance
≥ 5000 MΩ (500 V DC)
Conductivity (Contact Resistance Between Shells)
Olive drab cadmium: 1 mV
Chemical nickel: 1 mV
Passivation: 10 mV
Titanium alloy oxide: 15 mV
Nickel-plated stainless steel: 1 mV
Shielding
100 MHz: 90 dB
1 GHz: 85 dB
10 GHz: 55 dB
Contact Resistance (Lead silver conductor & protection)
#20 – 7.4 mΩ
#16 – 3.8 mΩ
#12 – 1.6 mΩ
#8 – 0.5 mΩ
#4 – 0.1 mΩ
Dimensions
Square Flange – Insert Arrangement Overview
Square-flange receptacle connectors use the same MIL-DTL-38999 Series III insert arrangements as the plug type, including high-density layouts such as 17-26, 19-11, 17-35, and 17-99.
These insert patterns support mixed-contact configurations, signal and power transmission, and high-reliability applications in aerospace, military, and industrial systems.
Since insert geometry remains identical across different shell styles, engineers can select a square-flange housing without changing wiring layout, pin numbering, or mating interface, ensuring seamless compatibility with plug and jam-nut receptacle versions.
Jam Nut – Insert Arrangement Overview
UNICONN jam-nut receptacle connectors use the same MIL-DTL-38999 Series III insert arrangements as the plug and square-flange versions, including layouts such as 17-26, 19-11, 17-35, and 17-99.
The jam-nut design provides fast and secure rear-mount installation, making it ideal for applications that require compact structure, quick assembly, and high vibration resistance.
As insert geometry remains consistent across all shell types, engineers can switch to a jam-nut receptacle without altering pin numbering, wiring layout, or mating compatibility.
This ensures seamless integration in aerospace, defense, and high-reliability industrial systems.
Wall Mount – Insert Arrangement Overview
UNICONN wall-mount receptacle connectors use the same MIL-DTL-38999 Series III insert arrangements as the plug, jam-nut, and square-flange versions.
Typical layouts include 17-26, 19-11, 17-35, 17-99, supporting high-density signal, mixed-power, and data transmission requirements.
The wall-mount shell design provides a rigid panel-mounted interface, ensuring excellent mechanical strength, stable grounding, and enhanced vibration resistance in aerospace, military, and heavy-industrial applications.
Because insert geometries are standardized, engineers can switch between different receptacle mounting styles without changing wiring diagrams, pin numbering, or mating compatibility, allowing seamless integration across system architectures.
Span-Wire Plug – Insert Arrangement Overview
UNICONN span-wire plug connectors utilize the same MIL-DTL-38999 Series III insert arrangements as standard plug versions, including high-density layouts such as 17-26, 19-11, 17-35, and 17-99.
This specialized shell design integrates a cable support structure, allowing the connector to be suspended on tensioned wires or harness branches without strain on the electrical contacts.
The extended rear body and reinforced strain-relief geometry provide excellent mechanical stability, vibration resistance, and cable routing performance, making span-wire plugs suitable for aerospace harnessing, UAV systems, platform wiring, and other demanding suspended-installation environments.
Because the insert geometry remains standardized across all MIL-DTL-38999 shell types, engineers can deploy span-wire plugs without altering pin numbering, wiring layout, or mating compatibility, ensuring seamless interchangeability with all corresponding receptacle styles.
Materials
Materials & Plating Options
UNICONN high-reliability circular connectors are manufactured using aerospace-grade materials to ensure long-term durability, corrosion resistance, and stable electrical performance.
Shell Materials
Aluminum Alloy (Lightweight) – Ideal for general aerospace, defense, and industrial applications requiring reduced mass and strong mechanical properties.
Stainless Steel (High-Strength / Corrosion-Resistant) – Suitable for harsh environments, chemical exposure, and high-vibration conditions.
Marine-grade Brass / Copper Alloy – Provides enhanced shielding performance and excellent conductivity.
Composite Shell (Lightweight / EMI-Resistant) – Offers weight reduction with superior EMI protection for avionics and UAV systems.
Plating Options
Electroless Nickel (EN)
Excellent corrosion resistance
High hardness and wear resistance
Meets MIL-DTL-38999 Series III requirements
Olive Drab Cadmium
Superior corrosion resistance
Widely used in military applications
Conductive surface supports EMI shielding
Black Zinc-Nickel
RoHS-compliant alternative to cadmium
High corrosion resistance
Non-reflective matte surface for tactical equipment
Chromate Conversion Coating
For enhanced corrosion prevention
Used on aluminum shells
Insert & Insulator Materials
High-Temperature Thermoset Polymer – Excellent dielectric strength and thermal stability.
Fluoropolymer-based Insulator Options – Supports extreme environments, chemical exposure, and aerospace requirements.
Contact Materials
Copper Alloy Contacts with:
Gold Plating (standard) for low contact resistance
Durable 50–100 µin Gold Flash for high-mating-cycle applications
Mechanical Performance
Mechanical Performance
UNICONN high-reliability circular connectors are designed to withstand vibration, shock, and harsh mechanical conditions commonly found in aerospace, defense, and industrial systems. All mechanical properties comply with high-performance requirements similar to MIL-DTL-38999 Series III standards.
Vibration Resistance
Sine Vibration: 10 Hz – 2000 Hz
Vibration Level: up to 196 m/s²（20 g）
Suitable for aircraft engines, vehicular platforms, UAV systems, and other high-vibration environments.
Random Vibration
Designed for high-intensity random vibration profiles
Supports avionics-grade vibration spectra
Maintains electrical continuity under dynamic loads
Shock Resistance
Mechanical Shock: up to 3000 m/s²（approx. 300 g）
Shock-resistant coupling mechanism ensures stable mating interface
Contact retention meets high-strength military requirements
Durability / Mating Cycles
500 – 1500 mating cycles depending on plating and shell material
Low-friction coupling design minimizes wear of contacts and insulators
Contact Retention
High pull-out force meets aerospace-grade specifications
Ensures stable electrical engagement under vibration and mechanical stress
Coupling Mechanism
Anti-decoupling structure with four-start threads
Fast mating, secure locking, and high vibration resistance
Continuous grounding between plug and receptacle
Mechanical Strength
Corrosion-resistant shell materials with high tensile strength
Rear accessory options for strain relief, backshells, boot adapters, and EMI shielding clamps
Environmental Performance
Environmental Performance
UNICONN high-density circular connectors are engineered to operate reliably under extreme environmental conditions, including high humidity, salt atmosphere, fluid contamination, temperature cycling, and outdoor exposure. All environmental properties follow high-performance requirements comparable to MIL-class interconnect standards.
Operating Temperature Range
–65°C to +200°C
(depending on shell material, plating, and insert type)
Humidity Resistance
Withstands 10 humidity cycling sequences without loss of insulation resistance
Sealing structure prevents moisture ingress and maintains long-term dielectric stability
Salt Spray Corrosion Resistance
Olive Drab Cadmium: up to 500 hours
Electroless Nickel / Zinc-Nickel: up to 48–96 hours
Designed for marine environments, coastal installations, and long-term outdoor exposure
Fluid Resistance
Compatible with commonly encountered aerospace and industrial fluids:
Hydraulic oils (Skydrol, phosphate ester fluids)
Aviation fuels
Lubricants and coolants
Cleaning solvents and de-icing chemicals
Environmental Sealing
Front and rear grommet seals ensure environmental protection
Optional sealing accessories support enhanced IP sealing requirements
Mated connectors can achieve IP67–IP68 depending on configuration
Temperature Cycling
Designed for repeated thermal shock cycles without structural degradation
Supports avionics and engine-compartment temperature variations
Rain & Water Spray Resistance
Resistant to 2 mm/min rain spray for extended exposure
Maintains coupling integrity and insulation properties under wet conditions
ELECTRICAL PERFORMANCE
Electrical Performance
UNICONN high-density circular connectors deliver stable electrical transmission under high-frequency, high-current, and EMI-critical environments. The electrical characteristics meet high-reliability interconnect requirements for aerospace, defense, and industrial platforms.
Insulation Resistance
≥ 5000 MΩ @ 500 V DC
Ensures excellent dielectric performance under humidity, contamination, and temperature cycling.
Dielectric Withstanding Voltage
1000 V AC – 1800 V AC depending on contact size and insert arrangement
Provides strong breakdown resistance for power and mixed-signal circuits.
Contact Resistance
High-conductivity copper-alloy contacts
0.1 mΩ – 7.4 mΩ across size #22 to #4 contacts
Maintains low-loss transmission for signal and power applications.
Current Rating
5 A to 50 A (based on contact size and wire gauge)
Supports high-density signal, data, and mid-power distribution requirements.
Shell-to-Shell Conductivity
Low resistance interface ensures continuous EMI shielding
Maintains grounding continuity even under vibration and mechanical shock
EMI / RFI Shielding Effectiveness
Up to 90 dB @ 100 MHz
55 dB @ 10 GHz
Suitable for avionics, communication systems, radar equipment, and high-frequency data links.
Protection Against Signal Degradation
Optimized contact geometry reduces micro-discontinuities
Stable performance under vibration, shock, and temperature variation
Compatible with differential signals and high-speed data protocols
Contact Plating
Hard gold plating on mating surfaces
Ensures low contact resistance and long-term durability
Suitable for frequent mating cycles and harsh environments
APPLICATIONS
UNICONN high-density circular connectors are designed for demanding environments where reliability, mechanical robustness, and EMI protection are critical. They are widely used across aerospace, defense, industrial, and high-performance electronic systems.
Aerospace Systems
Avionics modules
Flight control computers
Engine monitoring and sensor networks
Aircraft harnessing and power distribution
Defense & Tactical Equipment
Communication radios
Radar and surveillance systems
Vehicle electronics (tracked & wheeled platforms)
Weapon control and targeting systems
Unmanned Systems (UAV / UGV / USV)
Autopilot controllers
Real-time data transmission
Power and control harnessing
High-vibration propulsion modules
Industrial & Harsh-Environment Applications
Robotics and automation
High-vibration machinery
Railway and transportation electronics
Outdoor base stations and power modules
Marine & Offshore Electronics
Navigation systems
Subsea control modules
Salt-mist and high-humidity environments
High-Speed / High-Frequency Systems
High-speed data links
EMI-sensitive communication equipment
Mixed-signal and sensor networks
UNICONN connectors deliver long-term stability and secure mating performance, making them suitable for both mission-critical and high-reliability industrial applications.
Downloads
Technical resources for UNICONN high-density circular connectors will be available for download soon.
These documents will provide detailed specifications, ordering guidance, and design support for system integration.
For additional technical support, please contact our engineering team.