Views:4689 Author:Site Editor Publish Time: 2020-06-01 Origin:Site
A terminal is an accessory product used to achieve electrical connections, and is industrially divided into the category of connectors. With the increasing degree of industrial automation and the increasingly strict and precise industrial control requirements, the use of terminal blocks has gradually increased. With the development of the electronics industry, the range of use of terminal blocks is increasing, and the types are increasing. In addition to PCB board terminals, the most widely used are hardware terminals, nut terminals, spring terminals, and so on.
There are many types of terminals used. They can also be seen on high-end aircraft, but the terminals used on aircraft are electroplated. For most electronic terminals, the terminals must be surface-treated, which usually refers to electroplating. There are two main reasons:
1. Protect the terminal spring base material from corrosion;
2. Optimize the performance of the terminal surface, establish and maintain the contact interface between the terminals, especially the film control. In other words, it makes it easier to achieve metal-to-metal contact.
The reason why the terminal is to be plated, the analysis has the following points：
1. Anti-corrosion: Most terminal reeds are made of copper alloy, and they usually corrode in the use environment, such as oxidation and sulfuration. Terminal plating is to isolate the reed from the environment to prevent corrosion. Electroplated materials, of course, will not corrode, at least in the application environment.
2. Surface optimization: The terminal surface performance can be optimized in two ways. The first is the design of the terminal block, which establishes and maintains a stable terminal contact interface. The second is to establish a metallic contact, requiring that any surface film layer be non-existent or crack when inserted. The difference between the two forms without film breakage and film breakage is the difference between noble metal plating and non-noble metal plating. Precious metal plating, such as gold, palladium, and their alloys, is inert and has no film layer. Therefore, for these surface treatments, metallic contact is "automatic". What we have to consider is how to keep the nobleness of the terminal surface free from external factors such as pollution, substrate diffusion, and terminal corrosion. Non-metallic plating, especially tin and lead and their alloys, covers an oxide film, but when inserted, the oxide film is easily broken and a metallic contact area is established.
3. Increase the strong plating adhesion of the terminal (such as copper). For metals with poor adhesion, a copper base is usually used to enhance adhesion before plating.
4. Enhance the electrical conductivity of terminals (such as gold and silver). The conductivity of original materials such as iron and phosphor copper is usually less than 20%. Connectors with low impedance requirements cannot meet the requirements. Therefore, the surface can be electroplated with gold and other high conductivity metals to reduce their impedance.
5. Improve the solderability of the terminal (such as tin, gold, etc.). The reason is that the material has poor adhesion to tin. After plating a certain thickness of tin and other materials on the surface, the solderability of the part can be improved.
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