One article to understand the difference between PCB solder mask and solder flux layer

“Solder mask: solder mask, refers to the part on the board that needs to be painted with green oil; because it is a negative output, the actual effect of the part with solder mask is not green oil, but tinned, silvery white!

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Solder mask: solder mask, refers to the part on the board that needs to be painted with green oil; because it is a negative output, the actual effect of the part with solder mask is not green oil, but tinned, silvery white!

Soldering flux layer: paste mask, which is used when the machine is patched. It corresponds to the pads of all patch components. The size is the same as the toplayer/bottomlayer layer. It is used to open the stencil to leak tin.

Key Points:

Both layers are used for tin soldering, it does not mean that one is tinned and the other is green oil; then whether there is a layer that refers to the layer with green oil, as long as there is this layer in a certain area, it means that this area is What about insulating green oil?

For the time being I have not encountered such a layer! The pads on the PCB we drew have solder layers by default, so the pads on the produced PCB are covered with silver-white solder, and it is not surprising that there is no green oil; but the PCB we painted There is only a toplayer or bottomlayer layer in the wiring part on the board, and there is no solder layer, but a layer of green oil is applied to the wiring part on the finished PCB board.

That can be understood like this:

1. The meaning of the solder mask layer is to open a window on the green oil of the whole piece of solder mask, the purpose is to allow welding!

2. By default, green oil should be applied to the area without solder mask!

3. The paste mask layer is used for SMD packaging! SMT encapsulation uses: toplayer layer, topsolder layer, toppaste layer, and toplayer and toppaste are the same size, topsolder is a circle larger than them. DIP encapsulation only uses: topsolder and multilayer layers (after some decomposition, I found that the multilayer layer is actually the overlap of toplayer, bottomlayer, topsolder, bottomsolder layers), and topsolder/bottomlayer is a circle larger than toplayer/bottomlayer.

Question: Is the sentence “tin or gold plated only when the copper layer corresponding to the solder layer has copper”?

This sentence is said by a person who works in a PCB factory. What he means is: if the effect of the part painted on the solder layer is to be tinned, then the corresponding part of the solder layer must have copper skin (ie. : The area corresponding to the solderer layer should have a part of the toplayer or bottomlayer layer)!

Now come to a conclusion: “The copper layer corresponding to the solder layer will be tinned or gold-plated only when there is copper” This sentence is correct! The solder layer represents the area that does not cover the green oil!

mechanical, mechanical layer
keepout layer prohibits the wiring layer
top overlay top silk screen layer
bottom overlay bottom silk screen layer
top paste, top pad layer
bottom paste bottom pad layer
top solder top solder mask
bottom solder bottom solder mask
drill guide, via guide layer
drill drawing via drilling layer
multilayer

The mechanical layer defines the appearance of the entire PCB. In fact, when we talk about the mechanical layer, we mean the overall structure of the PCB.

The forbidden wiring layer is the boundary that defines when we are laying the copper with electrical characteristics, that is to say, after we define the forbidden wiring layer first, in the subsequent laying process, the wires with electrical characteristics that we have laid are impossible to exceed the forbidden wiring. layer boundaries.

topoverlay and bottomoverlay are silkscreen characters that define the top and bottom layers, which are the component numbers and some characters we generally see on the PCB.

toppaste and bottompaste are the top and bottom pad layers, which refers to the copper and platinum that we can see exposed outside, (for example, we draw a wire on the top wiring layer, what we see on the PCB is only It is just a line, it is covered by the whole green oil, but we draw a square or a point on the toppaste layer at the position of this line, and the square and this point on the board will have no green. Oil, but copper and platinum.

The two layers of top solder and bottomsolder are just opposite to the previous two layers. It can be said that these two layers are the layers to be covered with green oil. The multilayer layer is actually similar to the mechanical layer. As the name implies, this layer is Refers to all layers of a PCB board.

The two layers of top solder and bottomsolder are just the opposite of the previous two layers. It can be said that these two layers are the layers to be covered with green oil; because it is a negative film output, the actual effect of the part with the solder mask is not On green oil, but tinned, silvery white!

1. Signal layer
The signal layer is mainly used to lay out 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)
The Protel 99 SE provides 16 internal power/ground planes.
This type of layer is only used for multi-layer boards, mainly for arranging power lines and ground lines. We call them double-layer boards, four-layer boards, and six-layer boards, which generally refer 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 board dimensions, data marks, alignment marks, assembly instructions and other mechanical information.
This information varies depending on the requirements of the design company or PCB manufacturer.
Execute the menu command Design|MechanicalLayer to set more mechanical layers for the board. In addition, mechanical layers can be attached to other layers to output the Display together.

4. Solder mask layer
Apply a coating of paint, such as solder mask, to areas other than the pads to prevent tin from tinning in those areas.
Solder mask is used to match the pads during the design process and is generated automatically.
Protel 99 SE provides Top Solder (top layer) and Bottom Solder (bottom layer) two solder mask layers.

5. Paste mask layer (solder paste protective layer, SMD patch layer) It is similar to the solder mask layer, the difference is the pads of the surface-mounted components corresponding to the machine welding. Protel99 SE provides Top Paste (top layer) and Bottom Paste (bottom layer) two solder paste protection layers.

Mainly for SMD components on the PCB board. If the board is all placed with Dip (through hole) components, this layer does not need to export the Gerber file. Before attaching the SMD components to the PCB board, each SMD pad must be coated with solder paste. The paste mask file must be required for the tin-coated stencil before the film can be processed.

It is important to be clear about the Gerber output of the Paste Mask layer, that is, this layer is mainly aimed at SMD components. At the same time, compare this layer with the Solder Mask introduced above to clarify the different roles of the two, because it is seen from the film image. The two film images are very similar.

6. Keep out layer (prohibit wiring layer)
Used to define areas on the board where components and routing can be efficiently placed.
A closed area is drawn on this layer as a routing effective area, and automatic placement and routing cannot be performed outside this area.

7. Silkscreen layer
The silk screen layer is mainly used to place printing information, such as the outline and annotation of components, various annotation characters, etc.
Protel 99 SE provides Top Overlay and Bottom Overlay two silk screen layers. 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
The pads and penetrating vias on the circuit board need to penetrate the entire circuit board to establish electrical connection with different conductive pattern layers, so the system specially sets up an abstract layer – multi-layer.
Generally, pads and vias are arranged on multiple layers. If this layer is closed, the pads and vias cannot be displayed.

9. Drill layer
The drilling layer provides drilling information (such as pads, vias need to be drilled) during the manufacturing process of the circuit board.
Protel 99 SE provides Drillgride (drilling instructions map) and Drill drawing (drilling map) two drilling layers.