PCB Tech - ​What are these "layers" of PCB board manufacturers?

After the PCB board information is imported into the Protel 99SE design software, you can see that the circuit board is divided into many layers, and the color and shape displayed in the software are different for each layer. Let the PCB board manufacturer briefly introduce you to the PCB board. Layers.

1.Signal layer

The signal layer is mainly used to arrange the wires on the circuit board. Protel 99 SE provides 32 signal layers, including Top layer (top layer), Bottom layer (bottom layer) and 30 MidLayer (middle layer).

2.Internal plane layer (internal power/ground layer)

Protel 99 SE provides 16 internal power layers/ground layers. This type of layer is only used for multilayer boards, mainly used to arrange power lines and ground lines. We call double-layer boards, four-layer boards, and six-layer boards. Refers to the number of signal layers and internal power/ground layers.

3.Mechanical layer

Protel 99 SE provides 16 mechanical layers, which are generally used to set the external dimensions of the circuit board, data marks, alignment marks, assembly instructions and other mechanical information. This information varies depending on the requirements of the design company or PCB manufacturer. Executing the menu command Design|Mechanical Layer can set more mechanical layers for the circuit board. In addition, the mechanical layer can be added to other layers to output and display together.

4.Solder mask layer (solder mask layer)

Apply a layer of paint, such as solder resist, to all parts other than the pads to prevent tin on these parts. The solder mask is used to match the pads during the design process and is automatically generated. Protel 99 SE provides two solder masks, Top Solder (top layer) and Bottom Solder (bottom layer).

5.Paste mask layer (solder paste protective layer, SMD patch layer)

Its function is similar to that of the solder mask, but the difference is the corresponding surface-mounted component pads during machine soldering. Protel 99 SE provides two protective layers of solder paste, Top Paste (top layer) and Bottom Paste (bottom layer).

Mainly for SMD (Surface Mount Device) components on PCB boards. If all Dip (through hole) components are placed on the board, there is no need to export Gerber files on this layer. Before attaching SMD components to the PCB board, solder paste must be applied to each SMD pad. The stencil used for tinning must require this Paste Mask file, and the film can be processed.

The most important point of the Gerber output of the Paste Mask layer is to be clear, that is, this layer is mainly for SMD components. At the same time, compare this layer with the Solder Mask that will be introduced below to find out the different functions of the two, because from the film picture Look at these two film images are very similar.

6.Keep out layer (prohibited wiring layer)

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. Automatic layout and routing is not possible outside this area.

7.Silkscreen layer

The silk screen layer is mainly used to place printed information, such as the outline and annotations of PCB components, and various annotation characters. Protel 99 SE provides two silk screen layers, Top Overlay and Bottom Overlay. Generally, all kinds of marked characters are on the top silk screen layer, and the bottom silk screen layer can be closed.

8.Multi layer (multi-layer)

The pads and penetrating vias on the circuit board need to penetrate the entire circuit board and establish electrical connections with different conductive pattern layers. Therefore, the system is specially set up with an abstract layer-multilayer. Generally, the pads and vias must be arranged on multiple layers. If this layer is turned off, the pads and vias cannot be displayed.

9.Drill layer

The drilling layer provides drilling information during the manufacturing process of the PCB circuit board (such as pads and vias need to be drilled). Protel99 SE provides two drilling layers, Drill gride (drilling indication map) and Drill drawing (drilling drawing). Correspondingly, there are many layers in eagle (commonly marked with green)