The regular layer structure of printed circuit board includes Single Layer PCB, Double Layer PCB and Multi Layer PCB
Single board is a copper clad circuit board. Usually, the component is placed on the side without copper.The copper side is mainly used for wiring and welding as soldering surface. Single board is mainly installed pin plug-in components.
Tow sides of board covered with copper is named as Double board, generally one is Top Layer named as parts surface, and the other is Bottom Layer called as soldering surface. Pin plug-in components and SMD can be installed on this board. It is clearly that components and soldering surface is the same side for SMD.
Multilayer board includes many electronics circuit board and a plurality of intermediate conductive layers, except the top layer and the bottom.
The following figure is a typical structure of the 4-layer printed circuit board with 4 conductive layers, usually the top and the bottom layers are acted as signals. Two middle layers are used for power ,connection and also for signal line.Installation ways of components on a printed board are generally divided into in-line installation and surface mount.
Installation of components on a printed board, generally divided into in-line installation and surface mount.The in-line installation refers to the components of the pin inserted through the hole in the center of the pad and then welded on the other side . While surface mount refers to the components of the pin and the circuit board surface of the pad are fixed and connected by Tin Solder. In order to connect different layers of printed conductors, it is usually done by conducting holes (often called Vias). The conducting hole is drilled on the printed circuit board, then plated with a metal conducting layer on the hole wall, and communicated with the metal wires.
Structure Composition of PCB Circuit Board
Pad : for welding component pins of metal hole
Vias: metal vias and non metal vias, wherein the metal hole for connection between each layer components pins.
Mounting Hole：for fixed circuit boards
Conductor : for connecting the electrical network copper of components
Connector : for connecting components between circuit boards
Fill : for copper wire mesh,effectively reducing the impedance
Electrical boundary: for determining the size of the circuit board and all components on the circuit board can not exceed the boundary
The conductive hole is divided into perforation (hole), blind hole (Blind Via blind hole,which applied to the surface layer and one or more inner connection) and buried hole (Buried Via buried guide hole, the both sides of inner layer can not be seen after pressing, so as to save surface area.