In addition to the wiring on the substrate, the metal coating is where the circuit of the substrate is welded to the electronic components. In
addition, different metals also have different prices, which will directly affect the cost of production, and different metals also have different weldability, contact, and resistance values, which will also directly affect the efficiency of the component.
Commonly used metal coatings are:
1. Copper
2. Tin
The thickness is usually between 5 and 15 μm
3. Lead-tin alloy (or tin-copper alloy)
i.e. solder, usually 5 to 25 μm thick, with a tin content of about 63%
4. Gold
Generally, it will only be plated on the interface
5. Silver
Generally, it will only be plated on the interface or in the whole alloy, that is also silver
