6. Basic requirement of designing multiple layer PCB Juvtmall ( a company supply PCB Prototyping , PCBA service and sell kinds of components, modules and so on) Determine out shape, size, layers. Any plate, there are problems with other structural parts, so the shape and size of the printing plate must be based on the product machine structure. However, in terms of production process, it should be as simple as possible, generally for the long width ratio not too wide of the rectangle, to facilitate assembly, improve production efficiency, lower labor cost. The number of layers must be based on the circuit performance, the size of the plate and the intensity of the line. In the case of PCB multilayer, the application of four layers and six laminates is the most widely used, with four layers as an example, which is two conductor layers (surface and welding surface), a power supply layer and a layer. The layers of the multilayer should be symmetrical