How to improve salt spray corrosion resistance of circular metal connectors
Salt spray corrosion is one of the most common and most destructive atmospheric corrosion. The corrosion of metal surface by salt spray is caused by the electrochemical reaction between chloride ion penetrating the oxide surface and the protective layer on the metal surface and the internal metal. At the same time, the chloride ion contains a certain amount of hydration energy, which is easily absorbed by pores and cracks on the metal surface and replaces the oxygen in the chloride layer. Surface, causing damage to metallic materials.
Circular metal connectors are also prone to corrosion in harsh environments. The appearance and performance of corroded connectors have changed significantly, affecting their normal use. In order to overcome this problem, we must make a good choice of materials and structures, such as plating the surface of the contacts and the shell to prevent moisture in the air, so that water does not form inside the connector, and the shell It is not susceptible to salt spray corrosion.
As an important indicator for evaluating the environmental resistance of circular metal connectors, salt spray testing is often used as the main item for routine product inspection. With the continuous expansion of the scope of use of circular metal connectors, the environmental protection requirements of products are becoming higher and higher. The determination of salt spray levels of products has gradually attracted the attention of users and manufacturers.
In general, the factors that affect the salt spray resistance of circular metal connectors are mainly the following two
1, the quality of the substrate and coating structure.
For a circular metal connector, whether it is a contact or a housing, the quality of the base layer will affect the quality of the plating. The density, roughness, purity, and cleanliness of the substrate all affect the coating.
Due to the high requirements for the conductivity and wear resistance of circular metal connectors, most contact bodies are plated with silver or gold on copper and copper alloys. For the shell of a circular metal connector, the currently used plating structures are aluminum alloy plating, aluminum alloy zinc plating, brass nickel plating, brass chromium plating, etc. Among all metals, the cadmium coating has the best salt spray resistance. The cadmium coating is relatively stable and has strong corrosion resistance. It can be used in the marine atmosphere or in contact with seawater and hot water above 70 ° C. It was an early coating commonly used in marine environments. Cadmium coatings are now rarely used because cadmium is toxic and is basically used by other metals. Instead, it is used only for certain military products.
The shell of the circular push-pull self-locking connector produced by Shenzhen Maoke Electronics Co., Ltd. generally uses brass chrome plating, brass black chrome plating, brass pearl chrome plating, and brass nickel plating. Generally, the thickness of the coating is 0.05-0.1mm, and the abrasion resistance and corrosion resistance are very strong; the needle core is not plated with thin gold, only with thick gold. In the salt spray test, the time required for Shenzhen Maoke Electronics to pass the test can reach 144 hours.
2, Post-plating treatment process.
The reason for the poor resistance of circular metal connectors to salt spray is holes in the coating. If a suitable post-plating treatment process is used to reduce the porosity of the coating, the salt spray resistance will be greatly improved. For cathodic plating, post-plating must be performed, while for anodizing, post-plating can make the connector more stable to salt spray. For example, immersing the connector contact body of Mocorin Electronics in a gold-plated special protective agent for gold layer, which greatly reduces the corrosion phenomenon of the contact body and significantly improves the resistance to salt spray corrosion.
Therefore, according to the environmental requirements of circular metal connectors, the appropriate substrate and plating structure are selected, and after the plating is properly processed, the connector can well meet the salt spray resistance. User needs.