In Part 1 of this series we discussed the importance of electrical connector contact or terminal plating. In this blog we discuss the importance of connector shell plating as an important aspect of connector design, impacting its performance, durability, and cost.
Different plating materials serve specific purposes, and choosing the right one depends on the application. Here’s a breakdown of common plating options and their pros and cons. Each of these plating options — black electroplated (cation), electroless nickel, cadmium olive drab, and trivalent chromate — has specific characteristics that make it suitable for particular applications, especially in demanding environments. Here’s a closer look at the pros and cons of each:
1. Black Electroplated (Cation)
Pros:
- RoHS compliant.
- Aesthetic appeal: Provides a sleek, black finish that is often desirable for consumer electronics and automotive applications.
- Corrosion resistance: Offers superior corrosion resistance, withstands 500 hours of salt spray, especially when paired with an appropriate base layer (e.g., nickel or zinc).
- Electrical insulation: Some black finishes can be non-conductive, which may be useful for specific applications.
- UV resistance: Certain black electroplated finishes are UV-resistant, helping maintain aesthetic appearance in outdoor applications.
Cons:
- Conductivity issues: Some black finishes are non-conductive, which may not be suitable for all electrical applications.
- May not be military approved.
2. Electroless Nickel Plating (EN)
Pros:
- RoHS compliant.
- Uniform coating: Since it's applied chemically rather than electrically, electroless nickel provides even coverage, including use on complex shapes and internal surfaces.
- Offers shell to shell conductivity.
- Good corrosion resistance: Offers good corrosion resistance, 48 hours of salt spray resistance, particularly in environments exposed to chemicals or saltwater.
- Wear resistance: Electroless nickel is highly durable, with excellent wear and friction resistance.
- Hardness: The nickel-phosphorus alloy is hard, especially when heat-treated, making it suitable for rugged environments.
- Less conductive: Nickel has lower electrical conductivity compared to other plating options allowing it to be used in certain applications where it is necessary to prevent the flow of electricity and avoid any short-circuiting.
Cons:
- Cost: Electroless nickel can be more expensive than some other plating options.
- Thickness limitations: Achieving a very thick layer can be challenging and may require additional processing time.
3. Cadmium Olive Drab Plating
Pros:
- Superior corrosion resistance: Cadmium plating offers good corrosion resistance, 48 hours of salt spray resistance, even in harsh marine or industrial environments.
- Lubricity: Cadmium provides a naturally lubricated surface, which is ideal for threaded parts and reduces the risk of galling.
- Galling (aka cold Welding) is a phenomenon wherein adhesion occurs between two metal surfaces in sliding contact, resulting in frictional damage or seizing.
- Military standard: Olive drab cadmium is often specified in military and aerospace applications due to its reliability in harsh conditions.
- High conductivity: Cadmium is electrically conductive, making it suitable for applications requiring low-resistance connections.
Cons:
- Toxicity: Cadmium is toxic and environmentally hazardous, with strict regulations surrounding its use and disposal. Does not comply with EU Restriction of Hazardous Substances.
- Limited wear resistance: Although cadmium resists corrosion well, its softness can make it susceptible to physical wear in high-contact applications.
- Restricted availability: Due to health and environmental concerns, cadmium plating is less commonly available and highly regulated.
4. Trivalent Chromate Plating (Zinc with Trivalent Chromate Conversion)
Pros:
- RoHS compliant.
- Environmentally friendly: Trivalent chromate is less toxic than hexavalent chromate, making it a more environmentally acceptable choice.
- Good corrosion resistance: Often applied over zinc plating, it provides enhanced corrosion resistance in moderate environments.
- Widely accepted: Trivalent chromate is often specified in the automotive, welding and electronics industries due to its compliance with environmental regulations.
Cons:
- Lower corrosion resistance than hexavalent chromate: Trivalent chromate does not match the corrosion protection of its hexavalent counterpart.
- Lower durability: Not as wear-resistant as other plating options like electroless nickel or cadmium, limiting its use in high-friction applications.
- Conductivity concerns: Trivalent chromate may affect the conductivity of the surface, especially when thicker layers are applied.
Selecting the Right Plating
The selection of connector shell plating depends on several important application and operational factors including:
- Environmental conditions: Humidity, temperature, corrosive exposure.
- Mechanical durability: Frequency of connections/disconnections.
- Electrical requirements: Current, frequency, and signal integrity.
- Regulatory Compliance: Trivalent chromate and black electroplating are often favored for environmental compliance, as cadmium's use is restricted in many regions.
- Corrosion and Wear Resistance: For marine, medical and military applications, cadmium or electroless nickel is often preferred. Electroless nickel is ideal for its durability and uniform coating, especially in corrosive environments.
- Conductivity: If electrical conductivity is essential, cadmium, electroless nickel, and, in some cases, trivalent chromate over zinc are good choices.
- Aesthetic Needs: Black electroplated finishes provide a modern appearance, suitable for visible components in both industrial and consumer-facing applications.
- Cost considerations: Certainly upfront connector costs are an important consideration. These upfront costs need to be balanced against the longer-term durability (think downtime costs), performance reliability (think output optimization) and ongoing maintenance expenses (think replacement costs).
Each of these options has trade-offs, so the best choice will depend on balancing factors like environmental impact, cost, durability, and performance in the specific application environment.
Our connector experts can assist in finding the precise component for your spec. We can also provide samples for prototype design and testing.
Once the choice is made, we offer easy ordering via our website or work with our sales team to place your order, establish favorable terms, set up blanket orders and schedule deliveries so you have your components when and where you need them.
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Contact us to consult on the right plating technology for your application and operating environment.
Work with us how you prefer…call in by phone at (800) 662-1054, email sales@electroshield.com, or order at your convenience via our website.
