In the electronics and electrical industries, the use of protective and wear resistant coatings for connector contacts are increasing. Most of the connector contacts are surface treated. Do you know why?
As the core component of the electrical connector, the contact part can improve the corrosion resistance and wear resistance of the contact part through the table processing, and can also optimize the transmission function of the contact part to a large extent.
Contact plating material
When selecting a coating, the following factors are usually considered: the function of the contact, the operating condition, the matrix material, the degree of matching of the coating and the substrate, the cost of the coating, and the safety of the coating deposition environment.
Generally, the electrical connector contact material is copper alloy, and the commonly used coatings are: gold, silver, tin.
- Gold has very good electrical conductivity and conductivity is second only to copper and silver.
- Gold is an inert metal with very stable chemical properties.
- Gold has good wear resistance.
If the connector has high environmental resistance requirements and high reliability requirements, the surface of the contact parts is generally gold-plated.
Flexible application of gold plating
- Generally, the gold plating is nickel plating, which can improve the coating life.
- If the connector has cost requirements, the intermediate plating of the contact parts may be palladium-nickel alloy, and the outer plating layer shall be surface treated by thin gold plating.
In summary, gold plating is the most commonly used surface treatment method for contacts.
- Silver has the best conductivity.
- The chemical nature of silver is unstable, and it is easy to chemically change with sulfur in the atmosphere to produce silver sulfide. Silver sulfide will cause discoloration of the contact parts, and the electrical conductivity and welding performance will be greatly reduced.
- Silver has a cost advantage over gold.
If the connector has high electrical conductivity requirements or large operating current, the working environment is good, and the contact surface treatment can be silver plated.
The conductivity of tin is slightly worse than gold and silver, and the chemical properties are not stable enough, but tin has very good solderability.
In order to improve the solderability of the contact piece, the connector for the printed board can be partially tinned on the tail of the contact.
Tin plating is widely used on surface mount electrical connectors.
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