General PCB circuit board has called Single Layer PCB (single panel), Double Layer PCB (double-sided), four-layer board, plywood and so on.
Single panel is a single-sided copper, so use it to apply only one side of the design of the circuit conductors and components soldered copper.
Double panel including Top (top) and Bottom (bottom layer) are coated with a double-sided copper circuit board, double-sided wiring can be welded to the intermediate insulating layer, commonly used for a circuit board.
If you add another layer between the top and bottom double panel constitutes a multilayer, such as placing four boards of two power board layers, which is plywood.
An insulating layer between the PCB board generally includes top, bottom and middle layers, the layers used to isolate the wiring layer. Its heat-resistant material requirements and good insulation. Early Bakelite board more use of materials, and now more use of glass fiber-based.
After the PCB board layout copper conductor film, but also printed on the top and bottom layer of Solder Mask (solder resist layer), which is a special chemical substances, usually green. This layer non-stick solder, weld points to prevent adjacent excess solder shorts during welding. The solder resist layer covering the copper conductor film, a copper film preventing rapid oxidation in air, but remain in the position of the solder, the solder joints are not covered.
For double-sided or multilayer boards, solder layer is divided into a top and bottom surface of the solder resist layer solder layer two kinds.
Final stages of circuit board production, generally above the solder layer printed on some text symbols, such as the component name, component symbols, component pins and copyright, to facilitate future troubleshooting circuit welding and so on. This layer is Silkscreen Overlay (silkscreen). Solder layer of the multilayer Top Overlay (top surface printing layer) and Bottom Overlay (underside silkscreen).
