Four-layer board concept Four-layer board (4 layers) refers to the printed circuit board PCB. Printed Circuit Board is made of 4 layers of glass fiber, which can reduce the cost of PCB but has poor performance. Then how to distinguish four-layer boards, double-sided boards, single-sided boards, 6-layer boards --- etc. The following is an introduction to the method of distinguishing the number of PCB layers: (1) By looking at the cross-section of the PCB board, in fact this method is more difficult Yes, few people have this kind of vision. (2) It can be identified by observing the guide hole. If you can find the same guide holes on both sides of the PCB board, or if the motherboard or graphics card is facing the light source, if the position of the guide holes cannot transmit light, it is a four-layer board. www.zgmumen.com Four-layer board copying method Four-layer board copying is a PCB board whose components have been removed and the surface is clean. We need to copy it into a PCB file. Follow the steps below: 1. Scan the top board. Save the image and name it top.jpg. At this time, the scanning DPI can be set according to the density. For example, the setting is 400DPI. 2. Scan the bottom board, save the picture, and name it bottom.jpg. 3. Grind out the middle layer 1 with coarse sandpaper to remove the copper. Clean it and scan the picture, and name it mid1.jpg. 4. Use middle layer 2 Grind it out with coarse sandpaper and expose the copper skin. After cleaning, scan the picture and name it mid2.jpg. 5. Adjust the level of each picture in PHOTOSHOP (choose to rotate the picture to ensure that the picture is level, so that the lines will look good and have more lines. The pictures are easy to align up and down). It is recommended to mirror the bottom picture horizontally so that the top and bottom pictures have the same direction and the upper and lower positioning holes are consistent. Finally, save each picture as a BMP file, such as: top.bmp, bottom.bmp, mid1.bmp, mid2.bmp. Note here that you don't need to crop the picture exactly, it's better to leave some room for it. Basically, just level the picture and you're done. 6. Open the color copy board software, select "File" -> "Open BMP File" from the main menu, and select the top.bmp file to open. 7. After setting the DPI, you can copy the top-level image. First, select the layer to the top layer. Then start placing components, vias, wires, etc. 8. After putting everything on the top level, save the temporary file (available in the manual and help, you can choose it through the menu or the button on the toolbar) and name it top-1.dpb (saved at different times in the middle) It is recommended to use names with different numbers, such as top-1.dpb, top-2.dpb. This will prevent the last file from being destroyed due to computer failure, but the previous version of the file can still be restored to reduce losses. This is a suggestion. It depends on the individual. Hobby). 9. Close the current picture window (note that only one picture can be opened at a time, never open multiple pictures). 10. From the main menu "File" -> "Open BMP file", select the bottom image bottom.bmp, and then open the temporary file top-1.dpb. At this time, you will find that the top-level drawing and the bottom background image are not aligned. Press Ctrl A key combination, select all the placed graphics elements, press the up, down, left, and right cursor keys on the keyboard or the 2, 4, 6, and 8 numeric keys to move as a whole, and select several reference points and corresponding points in the background image After alignment, you can select the current layer as the bottom layer, and then use the bottom layer lines, pads, fills, etc. What should you do if the top layer lines block the bottom layer? It's very simple. You can select "Layer Color Settings" from the main menu "Options" and uncheck the top layer. The top layer silk screen can also be turned off. After copying the bottom layer, save the temporary file as bottom-1.dpb, or save the PCB file as bottom-1.pcb. At this time, the file is already a two-layer aligned and combined file. 11. The process of copying the middle layer is the same. Repeat steps 9~10. The final output PCB file is the four-layer PCB diagram that is exactly the same as the real thing.