How many layers are the best for PCB design?

How many layers are the best for PCB design? One article will help you understand the meaning of PCB layers.

PCB has many layers. When beginners begin to learn PCB design, they are easily confused by various layers. To this end, we have made a summary of the layers in the PCB to help you better understand and master.

Definition of layers in PCB design

01 Mechanical Layers
The mechanical layer is generally used to place the indicative information about the board making and assembly method, such as the overall dimensions, dimension marks, data data, through-hole information, assembly instructions and other information of the PCB.

02 Keep Out Layer
It is used to define the area where components and wiring can be effectively placed on the circuit board. Draw a closed area on this layer as the effective area for routing, and you cannot automatically layout and route outside this area.

03 Silkscreen layer
The screen printing layer is a text layer, which belongs to the top layer of the PCB and is generally used for annotation.
(1) Top Overlay
It is used to mark the projected outline of components, label, nominal value or model of components and various annotation characters.
(2) Bottom Overlay
Same as the top screen layer, if all the marks on the top screen layer have been included, the bottom screen layer can be closed.

04 Solder Mask
Solder resistance layer refers to the part on the printed circuit board to be painted with green oil. In fact, the solder mask layer uses negative film output, so after the shape of the solder mask layer is mapped to the board, it is not the green oil solder mask, but the copper skin is exposed.

05Multi Layer
The pads and through-type vias on the circuit board should penetrate the entire circuit board and establish electrical connection with different conductive graphic layers. Therefore, the system specially sets an abstract layer – multilayer. Generally, pads and vias should be set on multiple layers. If this layer is closed, pads and vias cannot be displayed.

06 Drill Layer
The drilling layer provides the drilling information during the manufacturing process of the circuit board (such as pads, through holes need to be drilled).

07 Signal Layers
(1) Top Layer
Also known as component layer, it is mainly used to place components. For double-layer board and multi-layer board, it can be used to lay wires or copper clad.
(2) Bottom Layer
Also known as welding layer, it is mainly used for wiring and welding, and can be used to place components for double-layer boards and multi-layer boards.
(3) Mid-Layers
There can be up to 30 layers, which are used for arranging signal lines in the multi-layer board, excluding power lines and ground wires.

08 Internal Planes
Usually referred to as internal electrical layer, it only appears in multilayer boards. The number of PCB layers generally refers to the sum of the signal layer and internal electrical layer. The same as the signal layer, the internal electrical layer and the internal electrical layer, and the internal electrical layer and the signal layer can be connected through the through hole, blind hole and buried hole.

Expansion: How many layers are the best for PCB design?

According to the number of circuit layers, PCB boards can be divided into single panel, double panel and multilayer board. So, in PCB design, how many layers of boards are the best?

In fact, there is no unified answer. It requires PCB designers to weigh how many layers to select for design according to the complexity of the whole circuit designed, mainly determined by the outgoing line of core devices and the difficulty of device layout in the whole project.