多层PCB 层叠结构　　在设计多层PCB 电路板之前，设计者需要首先根据电路的规模、电路板的尺寸和电磁兼容（EMC）的要求来确定所采用的电路板结构，也就是决定采用4 层，6 层，还是更多层数的电路板。确定层数之后，再确定内电层的放置位置以及如何在这些层上分布不同的信号。这就是多层PCB 层叠结构的选择问题。层叠结构是影响PCB 板EMC 性能的一个重要因素，也是抑制电磁干扰的一个重要手段。本节将介绍多层PCB 板层结构的相关内容。-The laminated structure of the multilayer PCB before the design of multilayer PCB circuit board, designers need to according to the size and scale of the circuit board circuit, electromagnetic compatibility (EMC) circuit board structure to determine the requirements of the, is decided to adopt 4 layers, 6 layers or more layers of circuit board. Determine the number of layers, and then determine the position of the inner layer of the layer and how to distribute different signals on these layers. This is the choice of multilayer PCB stack structure. Stacked structure is one of the important factors that affect the performance of EMC board PCB, and it is also an important means to suppress electromagnetic interference. This section will introduce the related content of the multi-layer PCB board structure.