A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate,it is base board to assemble the components. PCBs bring standardization of interconnection of components which will make the components easy to install and use.PCBs not only play the role of assembly and wiring fixing in in the electronic product,providing the required electrical characteristics,such as characteristic impedance,but also offering the identify characters and graphics for maintenance of components.Almost all of electronic devices refer to PCBs,it is so called "the mother of electronic system products."More importantly, there is no alternative to provide mature technologies and products with the same or similar function of PCBs. Irreplaceability of PCB is one of factors which make PCB developing well.PCB is directly related to the overall quality of the reliability of electronic products, thus affecting their overall level of the system.