The main metal components of metal terminal blocks include conductive strips, screws, and clamping parts, with the key being the copper content of the conductive strips. In the national standards "plugs and sockets for household and similar purposes" (GB 2099) and "switches for fixed electrical installations for household and similar purposes" (GB 16915), it is explicitly stipulated that the copper content should be at least 58%. Copper has excellent metal processing properties and high corrosion resistance; Copper has excellent conductivity, second only to silver. Therefore, copper is particularly suitable for forming electrical and mechanical connection components such as composite terminals. Copper metal parts and copper wires have almost the same coefficient of thermal expansion, which avoids different degrees of thermal expansion under large temperature fluctuations, thus avoiding mechanical stress in the terminals and preventing loose connections caused by it. The material of screws and clamping parts is generally copper alloy or steel with surface electroplated anti rust materials. The key is to have anti-corrosion performance and sufficient mechanical strength. In principle, steel without surface electroplated anti rust materials should not be directly used. This can avoid the battery effect of steel metal parts and copper wires in damp conditions, and avoid the occurrence of unreliable electrical connections and screw rust caused by electrical corrosion. Usually, the surface of steel components requires nickel plating treatment, which can have a certain anti-corrosion effect.