1. According to the number of layers, circuit boards are categorized into three main types: single-sided, double-sided, and multi-layer circuit boards. The first type is a single-sided panel.

2. On the most basic PCB, components are concentrated on one side, while the wiring is on the other. Since the wiring is only present on one side, this type is referred to as a single-sided circuit board.

3. Some PCB manufacturers note that single-sided boards are typically simple to produce and low in cost; however, their limitation is that they cannot accommodate overly complex designs.

4. Double-sided boards are an extension of single-sided boards. When single-layer wiring cannot meet the requirements of electronic products, double-sided boards become necessary.

5. Both sides are equipped with copper-clad wiring, and the lines between the two layers can connect through vias to establish the required network connections.

6. A multi-layer board refers to a printed circuit board that contains more than three conductive layers, with insulating material laminated between them. The conductive patterns are interconnected as needed.

7. Multi-layer circuit boards represent the evolution of electronic information technology towards higher speed, multifunctionality, larger capacity, and reduced size and weight.

8. Circuit boards can be classified into flexible boards (FPC), rigid boards (PCB), and rigid-flex boards (FPCB) based on their characteristics.

9. The following is an introduction to the key steps in the PCB printed circuit board production process.

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