PCB is made of different components and a variety of complex process technology, including the structure of PCB circuit board has a single layer, double layer, multi-layer structure, different levels of the structure of its production is different.
First, the printed circuit board is mainly composed of a pad, hole, mounting holes, wires, connectors, electrical components, filling, boundary etc., the main function of each part are as follows:
Pad: metal hole for welding component pins.
A metal hole used to connect the component pins between the layers.
Mounting hole: for fixing printed circuit boards.
Conductor: electrical network copper film for connecting component pins.
Connector for connecting components between circuit boards.
Fill: copper for the ground network, can effectively reduce the impedance.
Electrical boundary: used to determine the size of the circuit board, all components on the circuit board should not exceed the boundary.
Second, printed circuit board common board structure, including single layer board (Single Layer PCB), double layer board (Double Layer PCB) and multilayer board (Multi Layer PCB), the three kinds of board structure is briefly described as follows:
(1) a single layer plate: a circuit board with only one side of the copper deposited on the other side without copper. Usually placed on the side of the copper, copper side is mainly used for wiring and welding.
(2) double layer board: that is, the two sides are deposited copper circuit board, usually referred to as a top Layer (Top), the other side of the bottom (Bottom Layer). Generally placed as the top surface of the components, the bottom as a component welding surface.
(3) multilayer board, which includes a number of working level circuit board, in addition to the top and the bottom layer also contains a number of intermediate layers, usually the middle layer can be used as conductor layer, signal layer, power supply layer, ground layer, etc.. The layers are connected with each other, and the connection between the layer and the layer is realized through the through hole.
Third, the printed circuit board includes many types of work, such as signal layer, protective layer, screen printing layer, the internal layer, the role of various levels are briefly described as follows:
(1) signal layer: mainly used for placing components or wiring. Protel DXP usually contains 30 intermediate layers, namely Mid Layer1~Mid Layer30, the middle layer is used to arrange the signal line, the top and the bottom for placing components or deposited copper.
(2) protective layer: mainly used to ensure that the circuit board does not need to be tinned without tin plating, so as to ensure the reliability of circuit board operation. The Top Paste and Bottom Paste respectively, top solder layer and bottom solder layer; Top Solder and Bottom Solder respectively. The protective layer and the underlying solder paste mask layer.
(3) screen printing layer: mainly used in printed circuit board printing components production number, serial number, company name etc..
(4) internal layer: mainly used as signal wiring layer, Protel DXP contains a total of 16 internal layers.
(5) other layers: mainly consists of 4 types of layers.
Drill Guide (borehole azimuth): primarily used for drilling holes on printed circuit boards.