Functions of each layer in the Bare PCB board

Many bare PCB board design enthusiasts, especially novices, do not have a sufficient understanding of the various layers in bare PCB board design, and do not know their functions and usage. Here is a systematic explanation for you:

1. The mechanical layer is the appearance of the entire bare PCB board for mechanical finalization. In fact, when we talk about the mechanical layer, we mean the shape and structure of the entire bare PCB board. It can also be used to set 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. In addition, mechanical layers can be attached to other layers to output the display together.

2. Keep out layer (forbidden wiring layer), used to define the area where components and wiring can be effectively placed on the bare PCB board. A closed area is drawn on this layer as a routing effective area, and automatic placement and routing cannot be performed outside this area. The forbidden wiring layer is the boundary when we define the copper of the electrical characteristics, that is to say, after we define the forbidden wiring layer first, in the subsequent wiring process, it is impossible for the wires with electrical characteristics to exceed the forbidden wiring. The boundary of the layer is often used to use the Keep out layer as a mechanical layer. This method is actually wrong, so it is recommended that you distinguish it, otherwise the board factory will give you attribute changes every time you produce.

3. Signal layer: The signal layer is mainly used to arrange the wires on the bare PCB board. Including top layer (top layer), bottom layer (bottom layer) and 30 MidLayer (middle layer). Devices are placed on the Top and bottom layers, and the inner layers are routed.

4. Top paste and bottom paste are the top and bottom pad stencil layers, which are the same size as the pads. This is mainly because we can use these two layers to make stencils when we do SMT. We just dug a hole the size of a pad on the net, and then we put the steel mesh cover on the bare PCB board, and brushed the solder paste evenly with a brush with solder paste.

5. Top Solder and Bottom Solder This is a solder mask to prevent green oil coverage. We often say “opening the window”. Conventional copper or traces are covered with green oil by default. If we correspondingly cover the solder mask layer If handled, it will prevent the green oil from covering it and expose the copper.

6. Internal plane layer (internal power/ground layer): 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 planes.

7. Silkscreen layer: The silkscreen layer is mainly used to place printing information, such as the outline and labeling of components, various annotation characters, etc. Altium provides Top Overlay and Bottom Overlay two silkscreen layers, respectively, placing the top silk screen file and the bottom silk screen file.

8. Multi layer: The pads and penetrating vias on the bare PCB board should penetrate the entire bare PCB board and establish electrical connections with different conductive pattern layers. Therefore, the system has specially set 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 Drawing (drilling layer): The drilling layer provides drilling information in the manufacturing process of the bare PCB board (such as pads, vias need to be drilled). Altium provides Drill gride (drilling instructions map) and Drill drawing (drilling map) two drilling layers.

After the bare PCB board design is completed, the bare PCB board prototype needs to be carried out, and it is also crucial to choose a good bare PCB board prototype factory. Huihe Circuits adopts A-grade materials, masters professional bare PCB board production technology, and is equipped with reliable automatic production equipment, testing equipment and fully functional physical and chemical laboratories, whether you are doing communication equipment, automotive electronics, industrial control, or medical treatment. & security and other high-tech products, or need other bare PCB board services, Huihe Circuits provides you with more comprehensive and high-quality professional services.