Ad use summary--2__PCB in the various layers of the role of the detailed

All along, the PCB in each layer, such as: solder layer, paste layer, top overlay layer and so on these smattering. Look carefully today, to introduce you to the wrong place also please correct me.

1.mechanical mechanical layer is to define the overall appearance of the PCB, in fact, we say that the mechanical layer is the entire PCB board shape structure. The prohibition of wiring layer is defined in the cloth electrical characteristics of the copper boundary, that is, we have defined the prohibition of wiring layer, we in the subsequent cloth process, the cloth with the electrical characteristics of the line is not possible beyond the boundaries of the forbidden wiring layer.
Topoverlay and Bottomoverlay are the screen print characters that define the top and bottom, which is the component number and some characters that we see on the PCB board.

2.toppaste and Bottompaste is the top layer, the bottom solder plate layer, it means we can see the outside of the copper platinum, (for example, we draw a wire in the top layer of wiring, this wire we see on the PCB is just a line, it is covered by the whole green oil, But we draw a square on the toppaste layer in the position of this line, or a point, and the square on the plate and this point will not have green oil, but copper platinum.

3.topsolder and Bottomsolder These two layers just opposite to the front two layers, it can be said that the two layers is to cover the green oil layer, multilayer this layer is actually similar to the mechanical layer, Gu name apprentice, this layer refers to all the layers of the PCB board. Topsolder and Bottomsolder These two layers just opposite the front two layers, it can be said that these two layers is to cover the green oil layer: because it is negative output, so actually there is solder mask part of the actual effect is not on the green oil, but tin plating, silver. As a result, the actual effect is similar to the paste layer effect, which is the function of the pad out. Solder is an exposed pad, paste is used to paste solder paste on the pad. Another paste layer is mainly used for SMD (surface mount) components of the pad.

4.Signal layers (signal layer): The signal layer is mainly used to lay out the conductors on the circuit board. Includes top layer, Bottom layer (bottom), and 30 Midlayer (middle tier).

5.Internal plane Layer (internal power/ground plane): This type of layer is used only for multilayer boards, mainly for the arrangement of power lines and grounding wires. We call the double-decker, four-ply, six-ply, which generally refers to the number of signal layers and internal power/ground layers.

6.Mechanical layer (mechanical layer): it is generally used to set the board's overall dimensions, data markers, alignment marks, assembly instructions and other mechanical information. This information varies according to the requirements of the design company or PCB manufacturer. Execute menu Command design| The mechanical layer can set up more mechanical layers for the circuit board. In addition, the mechanical layer can be attached to other layers together to output the display.

7.Solder Masks Layer (solder mask): Apply a layer of paint, such as solder paint, to each part of the pad to prevent tin on these parts. The solder resist layer is used to match the pads during the design process and is automatically generated. Protel SE offers two solder-resistant layers for top Solder (top) and bottom Solder (bottom layer).

8.Paste mask Layer (solder paste protective layer, SMD patch layer): It is similar to the effect of solder mask layer, the difference is in the machine welding corresponding to the surface paste-type components of the pad. Protel-SE offers two solder paste layers for top Paste (top) and bottom Paste (ground floor). Mainly for SMD components on the PCB board. If the plates are all placed in dip (through hole) elements, this layer does not have to output the Gerber file. SMD components on the PCB board before, must be on each SMD pad first coated with solder paste, in the tin coated with the steel mesh must need this paste mask file, the film can be processed. Paste Mask Layer Gerber Output The most important point to be clear, that is, this layer is mainly for SMD components, at the same time the layer with the above-described solder mask to make a comparison, to understand the difference between the two, because the film in the film to see the picture is very similar.

9.Keep out layer (no wiring layers): Used to define areas where components and cabling can be effectively placed on the board. In this layer, a closed area is drawn as the routing active area, which cannot be automatically laid out and routed outside the area.

10.Silkscreen Layer (Silk screen): Screen printing layer is mainly used for placing printed information, such as the outline of components and annotations, a variety of comment characters. Protel-SE offers the top overlay and bottom overlay two silk print layers. In general, a variety of label characters are in the top layer of screen printing layer, the bottom layer of the screen can be closed.

11.Multi Layer (Multilayer): The circuit board and the penetration through the hole to penetrate the entire circuit board, with different conductive graphics layer to establish an electrical connection, so the system is specifically set up an abstract layer-multilayer. Generally, pads and vias should be set on multiple layers, if the layer is closed, the pads and vias can not be displayed.

12.Drill layer (drilling layer): The drilling layer provides drilling information in the manufacturing process of the circuit board (e.g. pads, holes need to be drilled). Protel-SE offers drill gride (drill-hole indicator) and drill drawing (drilling diagram) two drilling layers.

In particular, the solder mask layer and the paste mask layer need to be emphasized

Solder Mask: Solder masks, refers to the board on the green oil on the part, because it is negative output, so actually there is solder mask part of the actual effect is not on the green oil, but tin plating, silver.
Help solder layer: Paste mask, is the machine to use the patch, is corresponding to all SMD components of the pad, the size and Toplayer/bottomlayer layer, is used to open the steel network leakage tin.
Key points: Two layers are used for soldering, not refers to a tin, a green oil; Then there is no layer refers to the layer of green oil, as long as a certain area of the layer, it means that the area is insulated green oil. For the time being I have not met such a layer. We draw the PCB board, the top of the pad by default, there are solder layer, so made of PCB board part is on the silver-white solder, not on the green oil this is not strange; but we draw the PCB board on the line part, only the toplayer or Bottomlayer layer, There is no solder layer, but the PCB board is made of traces on the part of a layer of green oil.
That can be understood as follows: 1, solder resistance layer means that the whole piece of green Oil resistance welding window, the purpose is to allow welding.

2, by default, no solder layer of the area to be on the green oil.

                               3, paste Mask layer for SMD packaging. SMT package used: Toplayer layer, Topsolder layer, toppaste layer, and Toplayer and toppaste the same size, topsolder than their large circle. Dip package only used: Topsolder and Multilayer layer (after some decomposition, I found that the multilayer layer is actually toplayer,bottomlayer,topsolder,bottomsolder layer size overlap), and topsolder/bottomsolder than Toplayer/bottomlayer big circle.