Multilayer PCB Design

The most straightforward PCB layout designs are one or two-layer PCB designs. Sometimes we make multilayer PCB design; some of the multilayer guidelines are presented here.

- Stackup: This is one of the essential things when making a multilayer PCB design. Stackup is the number and the order of layers in a PCB design. Most manufacturers can support up to 16 sheets. In the illustrations below Figure 1, Figure 2, the most common four and six-layer PCB stack up are presented. Four-layer stack consists of a top and bottom layer (signal layers) and GND and VCC (power layers) in between. Six-layer stackup is the same as four-layer stack up just that between the power layers are two more signal layers (for example, high speed).


Figure 1 Four-layer PCB stack up


Figure 2 Six layer PCB stackup


For high-speed signals, as presented in Figure 2, a six-layer PCB stackup is a much better solution than a four-layer PCB stackup because the high-speed signals are more isolated, and the EMI is reduced which is very important in this kind of design. Multilayer PCB design.

Vias: Although the vias are necessary, the best is if only through-hole vias are used because this will make the design more cost-effective. Multilayer PCBs design If that is not possibly buried and blind vias are also available. Buried vias are connecting the internal layers, and blind vias are exposed only on one of two outer layers of the PCB.

PCB design where BGA (ball grid array) ICs are involved is one example where multilayer PCB design is almost always necessary due to the BGA escape routing, which is routing the traces from the BGA chip to the rest of the PCB.

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