About 4-layer PCB
A 4-layer PCB refers to a 4-layer circuit board to transmit electrical signals: top layer, inner layer 1, inner layer 2, and bottom layer. The top and bottom layers are the outer layers where we place components and wiring. Inner layer 1 and inner layer 2 are located at the core and are usually used as power planes or for signal routing. Therefore, 4-layer PCB=3 signal layer+GND layer or 4-layer PCB=2 signal layers+one VCC layer+one GND layer. For a 4-layer PCB, the power and ground planes are usually the inner layer, while the traces are on the outer layer. Because solid-state power supplies and ground planes help reduce electromagnetic interference emissions and improve the signal quality on the traces. In addition, it is much simpler to connect the components to the aircraft than to use traces to arrange the power tree and the ground tree. From an EMC perspective, the outer ground stack is the best. When using SMD components, the connection is on the same layer as the component, so no vias or via pads are required. In a space-constrained design, you can place more circuits on the other side of the board. Get further information about the thickness of 4 layers printed circuit board on AiPCBA.
There are 2 types of 4-layer PCB stacking. The standard 4-layer PCB stacking is as follows. GND and VCC can be switched according to the layer with more signals. Signal GND VCC signal. If you don't want to connect all the ground pins through vias, there will be a different stack, and the path of the power supply on the signal is very flat.
This may be a better stack with a four-layer printed circuit board because the signal layer is the adjacent ground layer. A signal passes through a reference plane, its voltage is exactly at VCC, it will still return on this reference plane. In addition, the signal layer is tightly coupled to the adjacent plane. The ground layer can be used as a shield for the internal signal layer. You will get better results keeping your tracking plane height as low as possible. Multiple ground planes reduce the ground (reference plane) impedance of the circuit board and reduce common-mode radiation. Detailed introduction of different types of PCB Layers on AiPCBA is available now.
About 6-layer PCB
The 6-layer PCB is usually a 4-layer PCB with 2 additional signal layers added between the planes. The 6-layer PCB classic stack includes 4 wiring layers (2 outer layers + 2 inner layers) and 2 inner planes (one for the ground and the other for the power supply). By providing two buried layers for high-speed signals and two surface layers for routing low-speed signals, this greatly enhances EMI. The signal layer should be close to the adjacent plane.
The above design is a standard 6-layer PCB stack. But it is not suitable for all designs. For example, high-speed designs often keep power and ground planes on adjacent layers for decoupling, while designs that require low electromagnetic emissions may require additional ground layers for shielding. The last practicality to consider is to always route vertically on adjacent wiring layers. This helps improve routing efficiency and minimize cross-talk.
AiPCBA is a reputable PCB supplier with good pricing on 4 or 6-layer PCB prototypes. We can provide our customers with 4 and 6-layer PCB boards that use laminate materials to match the process of exposure to high temperatures during assembly. Open AiPCBA.com website, your order will be shipped within 72 hours. We do not charge for expedited fees and provide free shipping worldwide! You can get an instant online quote for a 6-layer PCB, just enter some specifications, such as PCB board size and quantity. Check it out if you want to know more about multi-layers PCB manufacturing process.