In addition to the wiring on the substrate, the metal coating is the place where the substrate line and electronic component are welded. In addition, different metals also have different prices, and different ones will directly affect the cost of production. Different metals also have different weldability and contact, as well as different resistance values, which will directly affect the effectiveness of the component.

　　Common metal coatings include:

　　copper

　　tin

　　The thickness is usually 5 to 15 μm

　　Lead tin alloy (or tin copper alloy)

　　That is welded, the thickness is usually 5 to 25 μm, and the tin content is about 63%

　　gold

　　Generally only plated in the interface

　　silver

　　Generally, it is only placed in the interface, or the alloy of silver with the whole