Printed circuit boards (PCBs), also known as circuit boards, are important electronic components and are known as the "mother of electronic components". 1. Traditional circuit boards are also known as printed circuit boards and printed circuit boards, as they are made by printing corrosion-resistant agents. At present, most circuit boards are coated with anti-corrosion agents (laminated or coated), and after exposure and development, the circuit board can be etched. 2. Circuit boards include single panel, double-sided board, and multi-layer board. In the most basic PCB, components on one side and wires on the other side are called single panels. The double-layer panel is covered with copper on both sides, and the lines between the two layers can be connected through through-holes to form the required network connection. Multilayer board refers to a printed board with three or more layers of conductive patterns, with insulating materials in the middle, and conductive patterns connected to each other as required. 3. The circuit board mainly consists of solder pads, through holes, installation holes, wires, components, connectors, fillers, electrical boundaries, etc. The main functions of each component are as follows: (1) Soldering pad: a metal hole used for welding components. (2) Through hole: includes metal through hole and non-metal through hole, where metal through hole is used to connect pins between layers of components. (3) Installation hole: used to fix the circuit board. (4) Conductor: Copper film mesh, used to connect component pins. (5) Connector: Used to connect components between circuit boards. (6) Filler wire: Copper wire used for grounding grids can effectively reduce impedance. (7) Electrical boundary: used to determine the size of a circuit board. Note: All components on the circuit board must not exceed the boundary. 4. The working principle of a circuit board is to use the insulation material of the board to separate it from the conductive layer of copper foil on the surface, allowing current to flow through various components along a pre designed route, completing functions such as work, amplification, attenuation, modulation, demodulation, encoding, etc.