PCB Fabrication

Talking about the factors that affect the effect of the document drawing of the circuit board copy board

by:A-TECH      2021-03-21
In the conventional PCB copy board, there are many factors that affect the effect of the file map. A good understanding of these factors can enable us to make a better PCB board. Next, we will analyze together what factors affect the file effect. Figure. Scanning process PCB scanning is the first step in the entire PCB copying process. To get a good PCB board, it must first be scanned by a computer, and the relevant parameters and the original PCB layout must be backed up. After dismantling the board, get the split PCB light board, and formally enter the stage of copying the board. The first thing to do is to scan to store and record the PCB image. This is a very important point. In order to ensure that the relevant parameters on the PCB are clearly visible after scanning, the stains and residual tin on the surface of the PCB should be removed before scanning. Since PCB copy board involves a problem of copy board accuracy, for circuit boards with high precision requirements such as mobile phone boards, it is necessary to copy high-precision PCB layouts. In the scanning process, the scanner needs to be accurately selected and set. First, ensure the accuracy of the original scanned image. It can be said that the accuracy of the copy board mainly depends on the original scanning accuracy. Here, it is necessary to introduce a concept of DPI. The meaning of DPI is the number of dots per inch. That is to say, the distance between every two points on the scanned image is 1000/DPI, the unit is mil. Then, in the mobile phone board copy, the DPI is set to 1000 when the PCB is scanned, and the distance between two points on the image is 1000/1000u003d1mil, which means that the accuracy at this time is 1mil. One thing to note is that the higher the accuracy of the scanned picture, the larger the picture and the higher the hardware requirements. Therefore, the DPI setting needs to be set according to the specific conditions of the original board to ensure that the next steps in the copying process can be Play the best results. After the software technology scans, we need to use the PCB copying software to complete the file map. In terms of software type, we have a fully functional copy board software, which is also very critical, because the choice of software can be reflected in the final exported PCB electronic layout and the resulting schematic diagram. After choosing a well-functioning software, in order to ensure the perfect effect, for the copying of double-layer boards and multi-layer boards, technically you should also have rich experience and skilled skills. Since the same double-layer or multi-layer PCB board has holes in the same position, but the circuit connection is different, then when drawing the wiring rules of the original board in the copying software, stack the top-level PCB file that has been copied from the double-layer board. On the scanned image of the other layer, the vias of the two overlapped, and then set the top line and silk screen to not display, and trace the lines of the other layer according to the position of the vias. In this way, the exported PCB file contains both sides of the double panel. data. The same applies to multi-layer boards, except that the surface layer needs to be polished with sandpaper after the surface PCB file map is traced, so that the inner layer wiring rules are exposed, and then copied with the same technique with the help of copying software. Advanced scanning technology, coupled with mature software operation skills, strictly follow the process of copying the board, you will find that the exported PCB file diagram or PCB electronic layout is in the wiring rules, via position, line direction and other parameters Will be consistent with the original PCB board. On the contrary, errors in any link in the middle, whether it is the accuracy setting of the scanning process, or the judgment and description of the wiring rules and functional modules of the copy board software, will affect the final effect of the PCB document diagram, so we should Attaches great importance. The scan of the inspection file map has been completed, and the next step is definitely to be tested. A double-panel file image detection method is to use a laser printer to print the two-layer file image on the surface of the transparent film, and then compare the film with the original board to check whether they are consistent. Of course, we should also test the electronic technical performance of the PCB board, and get the final parameters consistent with the original.
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