In the electronic and electrical industry, the application of point contact protection and the wear-resistant layer is increasing. As the core part of the electronic connector, the contact can improve the corrosion resistance and wear resistance function of the contact and optimize the transmission function of the contact to a large extent.
Incorrect selection of connector coating material or uneven or too thin coating thickness has a great impact on the connector. Last time a wiring harness processing factory purchased a batch of connectors, it was found that the terminal was not riveted tightly and the poor contact was found. The reason was found after help in the industry. Because the nickel plating was too thick and the bending was not enough, the riveting was not tight.
Therefore, the importance of coating for connector is self-evident. When selecting coating, the following factors should be considered: contact function, working condition, matrix material, matching degree of coating and matrix material, coating cost and safety of coating deposition environment.
The contact base material of the electronic connector is generally copper alloy, and the commonly used coatings are: gold, silver, tin, nickel, etc.
Characteristics of gold plating:
1. Gold has very good conductivity, which is second only to copper and silver.
2. Gold is an inert metal with very stable chemical properties.
3. The fittings have good wear resistance.
Applicable scenario: the connector has high requirements of environmental resistance and high reliability. Generally, the surface treatment of contact parts adopts gold plating.
Flexible application of gold coating:
1. The general gold-plated bottom coating is nickel, which can improve the coating life.
2. If the connector has cost requirements, palladium nickel alloy can be used as the intermediate coating of the contact, and the surface treatment method of thin gold plating can be used as the external coating.
To sum up, gold coating is the most commonly used contact surface treatment.
Characteristics of silver plating:
1. Silver has the best conductivity.
2. The chemical properties of silver are not stable, and it is easy to produce silver sulfide by chemical changes with sulfur in the atmosphere. Silver sulfide will lead to discoloration of contact parts, a significant decrease in electrical conductivity and welding performance.
3. Compared with gold, silver has a cost advantage.
Applicable scenario: the connector has the requirements of high conductivity or large working current, the working environment is good, and the contact surface treatment can be silver plating.
Characteristics of tinning plating:
The conductivity of tin is slightly worse than that of gold and silver, and its chemical properties are not stable, but tin has very good solderability.
Applicable scenario: to improve the solderability of contact parts, the connector for PCB can adopt the surface treatment method of local tin plating at the end of the contact parts.
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