1. Pad: Provide mechanical support for fixing and assembling various electronic components such as integrated circuits.
2. Routing: Realize wiring and electrical connection (signal transmission) or electrical insulation between various electronic components such as integrated circuits. Provide required electrical characteristics, such as characteristic impedance, etc.
3. Green ink and silk screen: Provide solder mask graphics for automatic assembly, and provide identification characters and graphics for component insertion, inspection, and maintenance.
