Any Printed Circuit Board has assembly problem with other structural parts, so the shape and size of PCB Board must be based on the product structure. However, from the production process point of view, it should be as simple as possible, generally the aspect ratio is not too large of the rectangle to facilitate the assembly, improve production efficiency and reduce labor costs. The number of layers must be based on PCB performance requirements, board size and line intensive degree. For the PCB multilayer board, the four layer board, six layer board is the most widely used, for example, the four layer board is the two wire layers, a power layer and a formation. The layers of the multilayer should be symmetrical, and preferably even copper layers, ie, four, six, eight and so on. Because of asymmetric lamination, the PCB board is prone to warping, especially for surface mount multilayer boards.