King Pin | Bead Electronics Blog

What You Need to Know about Plating for Electronic Connector Pins and Contacts

Posted by bead electronics on Nov 20, 2020 11:41:43 AM

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Choosing the right material for contact plating is critical for ensuring durability, conductivity, and resistance to corrosion to meet your connector needs. We have created an overview of common plating options for electronic connector pins and contacts. Read below to learn about various coating metals and their various applications. 

 

GOLD   

Most noble metal and is very resistant to corrosion. Excellent for low voltage and current applications. The coefficient of friction is low allowing for low insertion and withdrawal forces. Because of low wear, mating cycles can be high. High reliability and excellent wear properties allow for a long life in harsh environments.  (Typical plating thickness: 10-50 u”)

 

Common Applications:

  • Military/Aerospace
  • Automotive/Transportation
  • Healthcare/Medical
  • Communications
  • Connectors
  • Instrumentation/Sensors

 

 

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SILVER    

Is also a noble metal and has the highest electrical and thermal conductivity of all metals. It also has very low contact resistance. Silver does tarnish, but it is mitigated when contacts are mated and unmated. It is used mainly for high-current contacts.   (Typical plating thickness: 100-300 u”)

 

Common Applications:

  • Military/Aerospace
  • Automotive/Transportation
  • Healthcare/Medical
  • Communications
  • Lighting
  • Connectors
  • Instrumentation/Sensors
silver-plating-icon

 


 

PALLADIUM   

Similar resistance to corrosion as gold, and can be used as an alternative depending on the cost of each. Harder and more durable than gold and is more resistant to wear. Diffusion resistant when plating on copper. Copper readily diffuses into gold. Some disadvantages include reduced heat resistance, weakness to strong acids and more prone to cracking.   (Typical plating thickness: 10-30 u”)

 

Common Applications:

  • Military/Aerospace
  • Automotive/Transportation
  • Healthcare/Medical
  • Communications
  • Connectors
  • Instrumentation/Sensors

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PALLADIUM NICKEL   

The alloy has all of the advantages of palladium without the “fretting” issues or “brown powder” effect. Compared to palladium, palladium-nickel is less prone to cracking, is more resistant to heat and galvanic corrosion as well as allowing for reduced porosity and excellent solderability. PdNi followed by a gold flash offers more advantages, including acting as a solid lubricant, better corrosion protection and a higher number of mating cycles.  (Typical plating thickness: 10-30 u”)

 

Common Applications:

  • Communications
  • Connectors

 

palladium-plating-iconnickel-plating-icon

 


 

RHODIUM    

This plating has a high hardness (800 to 1000 Hv) and superior corrosion resistance. It is ideal for parts that require long-term stable contact resistance. It is used for switch contacts, test probe parts and some connectors. Heat resistance is very good, and it does not oxidize in air at 500 degrees C or lower.  (Typical plating thickness: 20 u”)

 

Common Applications:

  • Military/Aerospace
  • Connectors
  • Instrumentation/Sensors
rhodium-plating-icon

 


 

TIN

Unlike the above metals, tin is not in the noble category. It quickly develops an oxide layer when exposed to air. A contact system plated with tin requires greater forces and a longer wipe area to break through the oxide film. The higher coefficient of friction causes higher insertion and withdrawal forces and more wear, which limits mating cycles to less than 50. Whisker growth is a concern with close contact spacing. Tin offers excellent solderability and low cost. It is a very good finish for press-fit contacts.    (Typical plating thickness: 100-300 u”)

 

Common Applications:

  • Common - many applications

 

 

 

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TIN LEAD      

This finish has many similar properties as tin, without the whisker-growth. Its melting point is altered by lead content, but overall it is relatively low. Contact resistance and corrosion resistance are similar to tin, but solderability is improved. The finish provides lubricity, excellent conductivity and good shelf-life. Color ranges from matte gray to a bright, almost chrome-like appearance.   (Typical plating thickness: 100-300 u”)

 

Common Applications:

  • Military/Aerospace
  • Automotive/Transportation
  • Connectors

 

tin-plating-iconlead-plating-icon

 

 


 

WHITE BRONZE     

An alloy of copper, tin and zinc, this finish has gained popularity with RF connectors for a number of reasons. Because white bronze is non-magnetic, intermodulation concerns are diminished. Porosity is low as well as RF losses. Corrosion resistance is high and there is no discoloration, like silver. Compared to nickel, a common finish for connectors, health safety is improved.   (Typical plating thickness: 50-200 u”)

 

Common Applications:

  • Military/Aerospace
  • Healthcare/Medical
  • Connectors
copper-plating-icontin-plating-iconzinc-plating-icon

 


 

NICKEL   

Nickel plating is widely used in electronic components, such as connectors, contacts and integrated circuits. It is in the passive metal group and is often used for corrosion protection. It is very hard, durable and has high electrical conductivity. Nickel does form a hard oxide, but it is stable and does not grow continuously at the expense of the coating layer. For most battery contact applications voltages are high and current is driven through the oxide film. Nickel is commonly used as a diffusion barrier, preventing the migration of base material atoms to the top coating which is often gold. Because it is magnetic, it is not suitable for some RF type connectors.     (Typical plating thickness: flash – 300 u”)

 

Common Applications:

  • Common - many applications

 

 

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ELECTROLESS NICKEL

This nickel alloy coating is deposited by chemical reduction, meaning without electrical current as with nickel electroplating. Most electroless nickel deposits are alloyed with phosphorus in the range of 2-14%. The higher the phosphorus content the greater the corrosion resistance, but the hardness decreases. Compared to electrolytic nickel, electroless provides a more uniform thickness over the substrate, even in holes and ID’s. It is also less prone to porosity.    (Typical plating thickness: 50-300 u”)

 

Common Applications:

  • Military/Aerospace
  • Lighting
  • Instrumentation/Sensors

 

nickel-plating-iconcopper-plating-iconphosphorus-plating-icon

 

 


 

COPPER

Copper is a very electrically conductive metal, second only to silver. Unfortunately, it is prone to corrosion, which would impact conductivity. Using a protective layer could help avoid corrosion and most electronic connectors have nickel, tin or one of the noble metals applied after copper. Additionally, copper has excellent leveling and uniform deposition properties, which can help build up undersized parts.    (Typical plating thickness: flash – 200 u”)

 

Common Applications:

  • Primarily an underplate

 

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Conclusion

Bead Electronics can help you determine which material to use for your connector needs based on their application. We look forward to collaborating with you and helping you with your custom contact pin needs. Contact us today to speak with a contact pin and connector specialist. 

 

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