The design of the multilayer PCB

Multilayer PCB design Suggestions and examples: PCB design ( 4,6,8,10 layer board) Instructions and requirements: A: surface, surface for full ground plane ( Shielding) 。 B: no adjacent parallel wiring layer. C: all signal layer adjacent to ground plane as much as possible. D: the key signal and the adjacent formation, not across partitions. 4 layer PCB: plan 1: in a ground plane under the component surface, the key signal priority cloth in the TOP layer; As for the layer thickness, have the following Suggestions: 1:2: meet the impedance control core board ( GND to POWER) Shoulds not be too thick to reduce, the distribution of the ground plane impedance; Ensure the power plane decoupling effect. Scheme 2: defect 1: power supply, are too far apart, too much power source impedance plane 2: power supply, ground level because of the influence of element bonding pad and so on, very incomplete 3: because the reference plane is incomplete, signal impedance discontinuity. Solution 3:1 with similar, is suitable for the main device in the BOTTOM layout or key signal in the underlying routing. 6 layers PCB solution 3: to reduce a signal layer, the inside a layer, although for wiring level decreased, but the PCB design solves the scheme 1 and scheme 2 common defects. Advantages: 1: power supply layer and ground layer tightly coupled. 2: each signal layer directly adjacent to electric layer within, and other signal layer are the effective isolation, crosstalk is not easy to happen. 3: Siganl_2（ Inner_2) And two electric layer GND ( Inner_1) And the POWER ( Inner_3) Adjacent, can be used for high speed signal transmission. Within the two electric layer can effectively block the outside world to Siganl_2 ( Inner_2) Layer interference and Siganl_2 ( Inner_2) The rest of the world. Plan 1: using the four signal layer and layer 2 internal power/ground plane, with more signal layer, is conducive to the wiring between the work. Defect: 1: power supply layer and ground layer separate far away, not fully coupling. Layer 2: signal Siganl_2 ( Inner_2) And Siganl_3 ( Inner_3) Directly adjacent to the signal isolation is not good, easy to have crosstalk. 8 PCB 10 layers PCB summary: 1, PCB design of the key signal layer to, and adjacent to GND to adjacent and power in order to reduce the power plane impedance. 2, signal layer between adjacent, don't increase the isolation between signal, lest produce crosstalk. 3, signal layer adjacent to ground plane as far as possible, don't parallel wiring between adjacent layers. 4, for transmission line, the underlying the microstrip line model analysis, internal signal layer using stripline model. 6 layer / 10 layer / 14/18 signal on either side of the substrate layer is the most useful software. 5, if there are other power supply, priority in the signal layer thick line, try not to split formation. High-speed line best lining, the top bottom is vulnerable to the influence of ambient temperature, humidity, air, not easy to stability.