1. Working principle

The working principle of the circuit board is to isolate the conductive layer of the surface copper foil with the board-based insulating material, so that the current flows in various components along the pre-designed route to complete tasks such as work, amplification, attenuation, modulation, demodulation, encoding, etc. Features.

2. Composition

The circuit board is mainly composed of pads, vias, mounting holes, wires, components, connectors, thin film circuit SMT patches of the Waterford circuit board, thin film circuit SMT patches, filling, and electrical boundary of the Waterford circuit board. The main functions of each component are as follows:

Pad: A metal hole used to solder the pins of components.

Vias: There are metal vias and non-metal vias. Metal vias are used to connect component pins between layers.

Mounting hole: used to fix the circuit board.

Wire: The copper film of the electrical network used to connect the pins of the components.

Connectors: used to connect components between circuit boards.

Filling: used for the copper coating of the ground wire network, which can effectively reduce the impedance.

Electrical boundary: used to determine the size of the circuit board, all components on the circuit board cannot exceed the boundary.

3. Classification

The circuit boards are divided into three major categories: single-sided boards, double-sided boards, and multilayer circuit boards according to the number of layers.

Multilayer board: refers to a printed board with three or more conductive pattern layers laminated with insulating materials between them, and the conductive patterns between them are interconnected as required. Multilayer circuit boards are the product of the development of electronic information technology in the direction of high speed, multi-function, large capacity, small volume, thinner and lighter weight.

Single panel: On the most basic PCB, the parts are concentrated on one side, and the wires are concentrated on the other side. Because the wires only appear on one side, this kind of PCB is called a single-sided circuit board. Single panels are usually simple to manufacture and low in cost, but the disadvantage is that they cannot be applied to products that are too complex.

Double panel: It is an extension of single panel. When single-layer wiring cannot meet the needs of electronic products, double panel is used. There are copper-clad wires on both sides, and the lines between the two layers can be connected through vias to form the required network connection.

Circuit boards are divided into flexible boards (FPC), rigid boards (PCB), and rigid-flex boards (FPCB) according to their characteristics.

4. Working level

The circuit board includes many types of working layers, such as signal layer, protective layer, silk screen layer, internal layer, etc. The functions of each layer are briefly introduced as follows:

(1) Protective layer: It is mainly used to ensure that the parts of the circuit board that do not need to be tinned are not tinned, so as to ensure the reliability of the circuit board operation. Among them, Top Paste and Bottom Paste are the top solder mask and the bottom solder mask respectively; Top Solder and Bottom Solder are the solder paste protection layer and the bottom solder paste protection layer, respectively.

(2) 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 arrange signal lines, and the top and bottom layers are used to place components or deposit copper.

(3) Silk screen layer: Mainly used to print the serial number, production number, company name, etc. of the components on the circuit board.

(4) Internal layer: Mainly used as a signal wiring layer. Protel DXP contains 16 internal layers.

(5) Other layers: Mainly include 4 types of layers.

Drill Guide (Drilling azimuth layer): Mainly used for the position of drilling holes on the printed circuit board.

Keep-Out Layer (forbidden wiring layer): Mainly used to draw the electrical border of the circuit board.

Drill Drawing (drilling drawing layer): Mainly used to set the drilling shape.

Multi-Layer (multi-layer): Mainly used to set multi-layers.

This article introduces the concept, working principle, composition, classification and working level of the circuit board. Depending on the design of the circuit board, the price will vary depending on the material of the circuit board, the number of layers of the circuit board, the size of the circuit board, the quantity per production, the production process, the smallest line width and line spacing, the smallest aperture and the number of holes. , Special craftsmanship and other requirements to determine.