The Purpose Of Metal Terminal Plating
For most hardware terminals, the terminals must be surface treated, which generally refers to electroplating.
There are two main reasons：
1. Protect the terminal reed 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.
1) Prevent corrosion
Most terminal reeds are made of copper alloy, and are usually corroded in the use environment, such as oxidation and sulfide. Terminal plating is to isolate the reed from the environment to prevent corrosion. The plating material, of course, should not corrode, at least in the application environment.
2) Surface optimization
The optimization of the surface performance of the hardware terminal can be achieved in two ways. One is the design of the connection terminal, establishing and maintaining a stable terminal contact interface. The second is to establish a metallic contact, requiring that any surface film is non-existent or will be broken during insertion. There is no difference between the two forms of film and film rupture, which is the difference between precious metal plating and non-precious metal plating.
Noble metal plating, such as gold, palladium, and their alloys, is inert and has no film itself. Therefore, for these surface treatments, metallic contact is “automatic”. What we have to consider is how to keep the surface of the terminal “noble”, free from external factors such as pollution, substrate diffusion, terminal corrosion, etc. Non-metal electroplating, especially tin and lead and their alloys, cover a layer of oxide film, but when inserted, the oxide film is easily broken, and a metallic contact area is established.