When specifying circular connector accessories for aerospace, defence, marine, or industrial applications, the choice of plating is critical. The right material finish ensures long-term corrosion resistance, conductivity, EMI/RFI shielding performance, and environmental sealing, even in the harshest operating conditions. This technical guide explains the strengths and weaknesses of the main plating options used across the EMCA Interconnect range, including our proprietary Hybrid Finishes designed as RoHS-compliant, cadmium-free alternatives for modern applications.
Connector backshells and accessories must withstand:
Corrosion and Salt Fog – tested under Salt Spray (Salt Fog) Testing per MIL and VG specifications.
Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) Shielding – low contact resistance between backshell and connector shell is vital.
High Vibration and Thermal Shock Resistance – plating must not crack, flake, or lose conductivity under stress.
Environmental Sealing – O-rings and interface areas rely on plating integrity to prevent galvanic corrosion.
Material Compatibility – dissimilar metals can accelerate corrosion if not sealed or carefully matched.
Regulatory Compliance – RoHS-compliant finishes are increasingly required, especially in Europe.
Technical Benefits:
High corrosion resistance (500 hrs salt spray).
Conductive electroless nickel only where needed → reliable EMI/RFI shielding.
Sealed O-ring interfaces reduce galvanic corrosion risk.
Excellent performance under high vibration and thermal cycling.
Commercial Benefits:
RoHS/REACH compliant, cadmium-free.
Intermateable with legacy finishes (Cadmium, ZnNi, Ni) → reduced inventory.
Visually appealing black or olive drab finishes to meet appearance or low-visibility requirements.
Use Case: The modern default choice for aerospace and defence connectors, balancing compliance, performance, and longevity.
Pros: Uniform coverage, excellent conductivity for EMI shielding, cost-effective, RoHS-compliant.
Cons: Only 48 hrs salt spray; not ideal for extended salt fog or marine environments.
Use Case: General-purpose aerospace and industrial applications where moderate corrosion resistance is sufficient.
Pros: High salt spray resistance (500 hrs), sacrificial protection, conductive base.
Cons: Finish may wear or discolor; regulatory status of chromates must be checked.
Use Case: RoHS-compliant replacement for cadmium in many military and aerospace designs.
Pros: Outstanding corrosion protection, proven Mil-Spec track record, excellent conductivity.
Cons: Cadmium is toxic and restricted under RoHS; soft finish wears faster.
Use Case: Required for legacy Mil-Spec programmes, but increasingly replaced by hybrids or ZnNi.
Pros: Inherently resistant to seawater corrosion, no plating layer to wear off.
Cons: Heavy, higher cost, galvanic issues with dissimilar metals.
Use Case: Specialist marine and naval applications where long-term seawater exposure is the dominant risk.
Pros: Excellent corrosion resistance, durable, no risk of plating flake or peel.
Cons: Heavier than aluminium, lower electrical conductivity, risk of thread galling.
Use Case: Extreme environments where durability outweighs weight and conductivity requirements.
| Requirement | Recommended Finish | Alternatives |
|---|---|---|
| Harsh marine / salt fog + RoHS compliance | Hybrid (J or U), Zinc-Nickel | Marine Bronze (if weight allows) |
| High vibration + thermal shock | Hybrid or Stainless Passivated | Electroless Nickel (thicker) |
| Weight-critical aerospace | Hybrid on aluminium | Cadmium (legacy only) |
| Legacy Mil-Spec requirement | Cadmium Olive Drab | Hybrid (if customer accepts) |
| RoHS-compliant, inventory reduction | Hybrid (J/U) | Electroless Nickel |
Proven Salt Spray Performance: 500 hrs MIL / 5 days VG.
Selective Plating Technology: Conductivity where needed, non-conductive coating elsewhere for superior sealing.
Reduced Inventory Complexity: Intermateable across multiple connector plating types.
RoHS and REACH Compliance: Cadmium-free, environmentally responsible.
For engineers balancing technical performance, compliance, and supply chain efficiency, EMCA Hybrid Finishes provide the best all-round solution.
The plating of a connector backshell directly affects its EMI/RFI shielding, corrosion resistance, conductivity, environmental sealing, and long-term reliability.
Hybrid Finishes (J & U) offer the best balance of compliance and performance.
Electroless Nickel remains a proven, economical choice.
Zinc-Nickel is a strong cadmium alternative.
Cadmium still excels technically but faces heavy restrictions.
Marine Bronze and Stainless Steel serve specialist niches.
By offering this complete range, EMCA Interconnect supports engineers in specifying connector accessories that perform in the toughest environments while meeting today’s compliance requirements.
For more information about our Black Hybrid finish view our video overview here.
