PCB circuit board composition and some of the main features
The PCB is made of different components and a variety of complex processing technologies. The PCB circuit board has a single-layer, double-layer, and multi-layer structure. Different hierarchical structures are produced in different ways.
Let's talk about the names and corresponding uses of the components of the PCB circuit board, and the main functions of the single-layer, double-layer, and multilayer structure of the pcb circuit board and various types of work.
First, the printed circuit board is mainly composed of pads, vias, mounting holes, wires, components, connectors, fillers, electrical boundaries, etc. The main functions of each component are as follows:
Pads: Metal holes used to solder component pins.
Via: Metal hole used to connect component pins between layers.
Mounting hole: Used to fix the printed circuit board.
Conductor: An electrical network copper film used to connect component pins.
Connectors: Components used to connect between circuit boards.
Fill: The copper used for the ground network can effectively reduce the impedance.
Electrical Boundary: Used to determine the size of the circuit board. Components on all circuit boards cannot exceed this boundary.
Second, the common board structure of printed circuit boards includes Single Layer PCB, Double Layer PCB, and Multi Layer PCB. A brief description of the three layer structures is given below. as follows:
(1) Single-layer boards: Circuit boards that have only one side of copper and no copper on the other side. The components are usually placed on the side without copper, and the copper side is used for wiring and soldering.
(2) Double-layer board: A circuit board with copper on both sides, usually called a top layer on one side and a bottom layer on the other side. The top layer is generally used as the placement component surface, and the bottom layer is used as the component welding surface.
(3) Multilayer board: It refers to a circuit board that includes multiple working planes. Besides the top layer and the bottom layer, it also contains several intermediate layers. Generally, the middle layer can be used as a wire layer, a signal layer, a power layer, a ground layer, and the like. The layers are insulated from each other, and the layers are usually connected by vias.
Third, the printed circuit board includes many types of working layers, such as the signal layer, the protective layer, the silk screen layer, and the internal layer. The roles of various layers are briefly described as follows:
(1) Signal layer: Mainly used to place components or wiring. Protel DXP usually contains 30 middle layers, namely Mid Layer1~Mid Layer30. The middle layer is used to lay out signal lines. The top layer and bottom layer are used to place components or copper.
(2) Protective layer: It is mainly used to ensure that no tin plating is needed on the circuit board, so as to ensure the reliability of the circuit board. Top Paste and Bottom Paste are the top solder mask and the bottom solder mask respectively; Top Solder and Bottom Solder are the solder resist and the bottom solder mask respectively.
(3) Silk screen layer: It is mainly used to print the serial number of components, production number, company name, etc. on the printed circuit board.
(4) Internal layer: Mainly used as a signal wiring layer, Protel DXP contains a total of 16 internal layers.
(5) Other layers: Mainly includes 4 types of layers.
Drill Guide: Mainly used for drilling holes in printed circuit boards.