The printed circuit board is mainly composed of pads, vias, copper film wires, working layers, and component packaging.

(1) Working level.

Due to the dense installation of electronic circuit components and special requirements such as anti-interference and wiring, the printed multilayer circuit boards used in many electronic products not only have upper and lower sides for wiring, but also have copper foil that can be specially processed in the middle of the board. For example, most of the conductive layers used in computers are more than 4 layers. These conductive layers are relatively difficult to process and are mostly used to set up power wiring layers with simpler wiring. Large-area filling methods are often used for wiring.

The working level of the printed circuit board can be divided into seven categories: signal layer, internal power/ground layer, mechanical processing layer, silk screen layer, protective layer, forbidden wiring layer and other layers. The specific role of each layer will be explained in detail in the setting of the board.

(2) Pad

The pad (PAD) is an element that electrically connects the component and the copper film wire in the printed circuit board. According to the difference of the soldering process, the pad can be divided into a non-via pad and a via pad. Generally, surface mount components use 100-via pads, and non-via pads are only effective on the top layer; pin-type components use via pads, and over pads are effective in multiple layers.

The pads are divided into the following three categories according to their shapes:

1. Circular pad: The most widely used in printed circuit boards is the circular pad. The assembly and soldering of components generally use circular pads. When the abscissa and ordinate of the circular pad are not equal, Oval pads, for non-via pads. The main parameter is the size of the pad; for the via pad, it mainly involves the size of the pad and the size of the via. The default design of the pad provided by PORTEL99SE is twice the size of the via.

2. Rectangular pad: The rectangular pad is mainly used to mark the first pin of the component, and can also be used as the pad of the surface mount component. When the pad is set as a non-via pad, the size of the pad is generally required The setting is slightly larger than the pin size to ensure the reliability of soldering.

3. Octagonal pad: In general, it is rarely used, and octagonal pads are often used when wiring special requirements.