Composition and main functions of PCB. First, PCB is mainly composed of pad, via, mounting hole, wire, components, connectors, filling, electrical boundary, etc. the main functions of each component are as follows:
Pad: metal hole for welding component pins.
Via: a metal hole used to connect the pins of components between layers.
Mounting hole: used to fix the printed circuit board.
Wire: copper film of electrical network used to connect the pins of components.
Connector: components used for connection between circuit boards.
Filling: copper coating for ground wire network can effectively reduce the impedance.
Electrical boundary: used to determine the size of the circuit board. All components on the circuit board shall not exceed the boundary.
2. The common board layer structures of printed circuit boards include single layer PCB, double layer PCB and multi layer PCB. The brief descriptions of these three board layer structures are as follows:
(1) Single layer board: that is, a circuit board with only one side coated with copper and no copper on the other side. Usually, the components are placed on the side without copper coating, and the copper coating side is mainly used for wiring and welding.
(2) Double layer board: a circuit board with copper coated on both sides. It is usually called top layer on one side and bottom layer on the other. Generally, the top layer is used as the surface for placing components, and the bottom layer is used as the welding surface for components.
(3) Multilayer board: a circuit board containing multiple working layers. In addition to the top layer and bottom layer, it also contains several intermediate layers. Generally, the intermediate layer can be used as conductor layer, signal layer, power layer, grounding layer, etc. Layers are insulated from each other, and the connection between layers is usually realized through vias.
Third, the printed circuit board includes many types of working layers, such as signal layer, protective layer, silk screen layer, internal layer, etc. the functions of various layers are briefly introduced as follows:
(1) Signal layer: mainly used to place components or wiring. Proteldxp usually contains 30 middle layers, namely midlayer1 ~ midlayer30. The middle layer is used to arrange signal lines, and the top and bottom layers are used to place components or copper coating.
(2) Protective layer: it is mainly used to ensure that the places on the circuit board that do not need to be tinned are not tinned, so as to ensure the reliability of the operation of the circuit board. Toppaste and bottompaste are the top layer and bottom layer respectively; Topsolder and bottomsolder are solder paste protective layer and bottom solder paste protective layer respectively. (3) Silk screen printing layer: it is mainly used to print the serial number, production number, company name, etc. of components on the printed circuit board.
(4) Internal layer: it is mainly used as the signal wiring layer. Proteldxp * * contains 16 internal layers. (5) Other layers: mainly including 4 types of layers.
(5) Other layers: mainly including 4 types of layers.
Drillguide (drilling orientation layer): it is mainly used for the location of drilling on printed circuit board.
