With the rapid development of mobile phone, electronics, communication industries, etc., it also promotes the continuous expansion and rapid growth of PCB circuit board industry, people have more and more requirements for the number of layers, weight, precision, material, color and reliability of components. Come higher.
However, due to the fierce market price competition, the cost of PCB board materials is also on the rise, and more and more manufacturers are monopolizing the market at low prices in order to enhance their core competitiveness. However, behind these ultra-low prices, it is obtained by reducing material costs and process manufacturing costs, but devices are usually prone to cracks (cracks), easy scratches, (or scratches), and their precision, performance and other comprehensive factors have not reached the standard. , which seriously affects the solderability and reliability of the product used.
The technical realization process of PCB copying is simply to scan the circuit board to be copied, record the detailed component positions, then remove the components to make a bill of materials (BOM) and arrange material procurement, and the empty board is The scanned image is processed by the copy board software and restored to a pcb board drawing file, and then the PCB file is sent to the plate making factory to make the board. After the board is made, the purchased components are welded to the finished PCB board, and then tested by the circuit board and debugging.
1. The specific steps of PCB copying
1. Get a PCB, first record the models, parameters, and positions of all the vital components on the paper, especially the direction of the diode, the triode, and the direction of the IC gap. It's best to take two pictures of the location of the element with a digital camera. Today's PCB circuit boards are getting more and more advanced. Some of the diodes and triodes above are not visible at all.
2. Remove all the multi-layer board parts, and remove the tin in the PAD hole. Clean the PCB with alcohol, and then put it into the scanner. When the scanner scans, it needs to slightly increase the scanned pixels to get a clearer image. Then lightly polish the top and bottom layers with water gauze paper until the copper film is shiny, put it into the scanner, start PHOTOSHOP, and scan the two layers in color. Note that the PCB must be placed horizontally and vertically in the scanner, otherwise the scanned image will not be available.
3. Adjust the contrast and brightness of the canvas so that the part with copper film and the part without copper film have a strong contrast, and then turn the second image into black and white to check whether the lines are clear, if not, repeat this step. If it is clear, save the picture as black and white BMP format files TOP.BMP and BOT.BMP. If there is any problem with the picture, you can use PHOTOSHOP to repair and correct it.
4. Convert the two BMP format files to PROTEL format files respectively, and transfer two layers in PROTEL. For example, the positions of PAD and VIA after the two layers are basically the same, indicating that the first few steps are well done. If there is any deviation , then repeat the third step. Therefore, PCB copying is a work that requires great patience, because a little problem will affect the quality and the matching degree after copying.
5. Convert the BMP of the TOP layer to TOP.PCB, pay attention to convert it to the SILK layer, which is the yellow layer, and then you can trace the line on the TOP layer, and place the device according to the drawing in the second step. After painting, delete the SILK layer. Keep repeating until all layers are drawn.
6. Transfer TOP.PCB and BOT.PCB in PROTEL and combine them into one picture.
7. Use a laser printer to print the TOP LAYER and BOTTOM LAYER on the transparencies respectively (1:1 ratio), put the film on the PCB, and compare whether there is any error. If it is correct, you are done.
A copy of the original board was born, but it was only half-finished. It is also necessary to test whether the electronic technical performance of the copy board is the same as that of the original board. If so then it's really done.
Remarks: If it is a multi-layer board, it should be carefully polished to the inner layer, and the copying steps of the third to fifth steps should be repeated at the same time. Of course, the naming of the graphics is also different, and it should be determined according to the number of layers. Generally, the double-sided board should be copied. It is much simpler than the multi-layer board, and the multi-layer copy board is prone to inaccurate alignment, so the multi-layer board copy board should be very careful and careful (the internal vias and non-conductive holes are prone to problems).
2. Double-sided copying method
1. Scan the upper and lower layers of the circuit board and save two BMP pictures.
2. Open the copy board software Quickpcb2005, click "File" and "Open Basemap" to open a scanned image. Use PAGEUP to enlarge the screen, see the pad, press PP to place a pad, and see the line and press PT to route... Just like a child's drawing, draw it again in this software, and click "Save" to generate a B2P file.
3. Click "File" and "Open Basemap" to open the scanned color image of another layer;
4. Click "File" and "Open" again to open the B2P file saved earlier. We see the newly copied board, stacked on top of this picture - the same PCB board, the holes are in the same position, but the line connections are different . So we press "Options" - "Layer Settings", and here we turn off the lines and silkscreens that display the top layer, leaving only the multi-layer vias.
5. The via holes on the top layer are in the same position as the via holes on the bottom layer picture. Now we can trace the bottom layer circuit like we did in childhood. Click "Save" again - at this time, the B2P file has the top and bottom layers of data.
6. Click "File" and "Export as PCB File", you can get a PCB file with two layers of data, you can change the board or re-print the schematic diagram or send it directly to the PCB plate making factory for production
Three, multi-layer board copying method
In fact, the four-layer board copying is to copy two double-sided boards repeatedly, and the sixth-layer board is to repeatedly copy three double-sided boards. The reason why multiple layers are daunting is that we cannot see the internal wiring. A precise multi-layer board, how do we see the inner layers of it? - Layered.
There are many ways of layering now, such as potion corrosion, knife peeling, etc., but it is easy to divide the layers too much and lose data. Experience tells us that sanding is the most accurate.
When we finish copying the top and bottom layers of the PCB, we usually use sandpaper to polish off the surface layer to reveal the inner layer; the sandpaper is the ordinary sandpaper sold in hardware stores, generally laying the PCB, and then pressing the sandpaper to rub evenly on the PCB (If the board is small, you can also lay the sandpaper flat, hold the PCB with one finger and rub it on the sandpaper). The point is to flatten so that it grinds evenly.
The silk screen and green oil are generally wiped off, and the copper wire and copper skin should be wiped a few times. Generally speaking, the Bluetooth board can be wiped in a few minutes, and the memory stick takes about ten minutes; of course, if you have a lot of strength, it will take less time; if you have less strength, it will take a little more time.
Grinding is currently the most common solution for layering, and it is also the most economical. We can try to find an abandoned PCB. In fact, grinding the board is not technically difficult, but it is a bit boring. It takes a little effort, and there is no need to worry about grinding the board to the fingers.
In the PCB layout process, after the system layout is completed, the PCB diagram should be reviewed to see whether the system layout is reasonable and whether the optimal effect can be achieved. It can usually be investigated from the following aspects:
1. Whether the system layout can ensure the reasonable or optimal wiring, whether it can ensure the reliable operation of the wiring, and whether it can ensure the reliability of the circuit operation. During the layout, it is necessary to have an overall understanding and planning of the direction of the signal and the power and ground network.
2. Whether the size of the printed board is consistent with the size of the processing drawing, whether it can meet the requirements of the PCB manufacturing process, and whether there is a behavior mark. This point needs special attention. The circuit layout and wiring of many PCB boards are designed beautifully and reasonably, but the precise positioning of the positioning connector is neglected, resulting in the designed circuit being unable to connect with other circuits.
3. Whether there is conflict between components in two-dimensional and three-dimensional space. Pay attention to the actual size of the device, especially the height of the device. When soldering layout-free components, the height generally cannot exceed 3mm.
4. Whether the component layout is dense and orderly, neatly arranged, and whether all the layouts are completed. When laying out components, not only the direction of the signal, the type of the signal, the places that need attention or protection, but also the overall density of the device layout should be considered, so that the density is uniform.
5. Whether the components that need to be replaced frequently can be easily replaced, and whether the plug-in board is easy to insert into the equipment. It should ensure the convenience and reliability of the replacement and connection of the frequently replaced components.
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