Multilayer board in the design of the time, the layers should be kept symmetrical, and preferably even copper layer, if not symmetrical, likely to cause distortion. Multilayer board wiring is based on the circuit function, in the outer cabling, the requirements of the welding surface and more wiring, components less wiring, is conducive to the maintenance and troubleshooting of the printed circuit board. In the alignment, the need to power layer, formation and signal layer separately, reducing the power, ground, signal interference. Adjacent two layers of printed circuit lines should be perpendicular to each other or slash, curve, can not walk parallel lines to reduce the substrate layer coupling and interference.
Multi-layer PCB with single-sided, double-sided, which is composed of which layers, each layer represents what, what is the use of it? The multilayer PCB consists of the following layers: Signal Layers, InternalPlanes, Mechanical Layers, Masks, Silkscreen, and System.
Signal layer is divided into top, middle, bottom, mainly used to place a variety of components, or for wiring, welding. The internal power plane is also called the internal layer, dedicated to the layout of the power cord and ground. The mechanical layer is typically used to place indicative information about the board and assembly methods, such as circuit board physical dimensions, data, and via information. The solder mask layer also has a top layer and a bottom layer, and the pad or other object placed on the layer is a copper free area. The silk screen layer is mainly used to draw the outline of the component, place the part number or other text information, and the system working layer is used to display information that violates the design rule check.