The following is for your reference:
1. Signal layer
The signal layer is mainly used to arrange the wires on the printed circuit board. Protel99SE provides 32 signal layers, including top layer, bottom layer and 30 mid-layer.
2. Internal plane layer
Protel99SE provides 16 internal power / ground layers. This type of layer is only used for muti-layers boards, mainly for the layout of power lines and grounding wires. We call it double-layers board, four layers board and six layers board, which generally refers to the number of signal layer and internal power / ground layer.
3. Mechanical layer
Protel99SE provides 16 mechanical layers, which are generally used to set the overall dimensions, data marks, alignment marks, assembly instructions and other mechanical information of the circuit board. This information varies according to the requirements of the design company or PCB manufacturer. Execute the menu command design| mechanical layer to set more mechanical layers for PCB. In addition, the mechanical layer can be attached to other layers to output the display together.
4. Solder mask layer
Apply a coat of paint, such as anti-soldering paint, to all parts outside the pad to prevent tin application. The PCB solder mask is used to match the pad in the design process and is generated automatically. Protel99SE provides two solder mask layers, top and bottom solders.
PCB layers name
5. Paste mask layer
It is similar to the function of the solder mask layer, but different from the pad of the corresponding surface bonding element when the machine is welded. Protel99SE provides top paste and bottom paste.