1. After installing the components, the telephone should be easy to use, that is, the electrical connection should meet the requirements;

2. The line width, thickness, and distance of the line meet the requirements to avoid heating, open circuit, and short circuit of the line;

3. The copper skin is not easily peeled off under high temperature;

4. The surface of copper is not easy to oxidize, which affects the installation speed. After oxidation, it will break down soon after use;

5. No additional electromagnetic radiation;

6. The appearance is not deformed to prevent deformation of the casing and misalignment of screw holes after installation. Now it is all mechanized installation, and the hole position of the circuit board and the deformation error between the circuit and the design should be within the allowable range;

7. High temperature, high humidity, and resistance to special environments should also be considered;

8. The mechanical properties of the surface should meet the installation requirements;