Printed circuit board layering, have you learned

When designing a PCB, many friends do not know enough about the layers in the PCB, especially newbies, the role of each layer is very vague. This time, let's look at the use of software Altium Designer drawing board, the difference between the layers.

1, the signal layer

Signal layer is divided into Top Layer (top), Bottom Layer (bottom), which is an important electrical equipment with a connection to the layer, can place some components, but also can be arranged to line.

2、multilayer pcb fabrication

Mechanical, defines the appearance of the entire PCB, emphasizing the "mechanical" means that it does not have electrical properties, so it can be safely used for sketching shapes, outlining the mechanical dimensions, location of the text, and so on, without having to worry about causing any changes to the electrical properties of the board. Up to 16 mechanical layers can be selected.

3. Silkscreen Layers

Top Coverage and Bottom Coverage are used to define the top and bottom screen printed characters, i.e. some text symbols printed on the soldermask, such as component names, component symbols, component pins and copyrights, for easy circuit soldering and error checking later.

4、Solder paste layer

The paste layer consists of the top paste layer and the bottom paste layer. The bottom paste layer is the exposed surface mount pad you see before soldering. This layer is also useful for hot air leveling pads and making soldering stencils.

5. Weld Resist Layer

Soldermask is also often referred to as the "window", including the top soldermask and bottom soldermask. Its role is the opposite of the solder paste layer, the solder paste layer is to cover the layer of green oil. This layer does not stick to the solder and prevents short circuiting of excess solder from neighboring solder joints during soldering. Soldermask covers the copper film conductor to prevent the copper film from oxidizing too quickly in the air, but leaves a position at the solder joints and does not cover the solder joints.

Conventional copper laying or alignment are a default cover green oil, if we need to carry out the corresponding in the soldermask layer to deal with the problem, then it will be covered by preventing green oil, will expose the copper.

6, drilling layer

Drilling layer consists of two drilling layers, namely, drilling grid map and drilling map. The Drill Hole Layer is used to provide drill hole information (e.g. pads that need to be drilled) during the PCB manufacturing process.

7. No Wiring Layer The No Wiring Layer is used to define the boundaries of the wiring layer. After the definition of the prohibited wiring layer, the wiring with electrical characteristics in the subsequent wiring process can not exceed the boundaries of the prohibited wiring layer.

8, multi-layer

Multi-layer, pads and through-holes through the entire circuit board, and different conductive graphics layer to establish electrical connection relationships, so the system specifically set up an abstraction layer - multi-layer. In general, pads and through-holes should be set in the multi-layer,PCB factory if you close this layer, pads and through-holes can not be displayed.

PCB multilayer pcb

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