What Is The Method For PCB Reverse Engineering?

Nowadays, there are many software for designing PCB board circuits. Such as Protel 99SE. POWER PCB, etc. But if you need to reverse engineer an off-the-shelf PCB, it can be a lot of work. In fact, in the current electronics industry production, PCB reverse engineering is often required.

Under normal circumstances, we will give the PCB board to PCB reverse engineering services professional companies such as (Shenzhen OROD Technology Co., LTD.) for them to complete the work.

But if we want to make a small change. It is more troublesome. At present, some software used for PCB reverse engineering are industry specific software. It's not something you can download for free on the Internet or buy from the marketplace. We have developed a detailed method for PCB reverse engineering that is relatively easy:

Equipment required for PCB reverse engineering: scanner, computer, Protel 99SE and AUTOCAD software.

1. Place the PCB you want to reverse into the scanner. Start the scanner, and pay attention to adjust the brightness and contrast in the scanner.

2. Open AUTO CAD software. Create a new CAD file and select Insert dot matrix image from the Insert menu. Select after the image you want to insert. The Insert Image dialog box appears. Select a ratio of 1:1 in the dialog box.

3. After inserting the PCB image, a rectangular frame should be drawn to cover the border of the PCB image. Note the object lock point that you will use to trace the object when drawing the border. If you do not draw the border, the image will accidentally move in the process of tracing the line drawing, and you will rarely be able to register.

4. Draw component encapsulation. Since we will be doing PCB reverse engineering, the component packaging may not be exactly the same as the component packaging in Protel 99SE. So we'll build our own component encapsulation. That is, we want to draw the shape of the components in the PCB. When plotting component packages, we need to count how many packages are used on the PCB. Only one of each package should be drawn. After all the packages are drawn, they should be transferred to Protel 99SE for further processing.

5. How to use Protel 99SE for PCB reverse engineering? Open Protel 99SE and create a new PCB file. Then select Import CAD file in the File menu of Protel 99SE PCB editor. Import the CAD file with the component model drawn. After the successful import, the Protel 99SE PCB editor appears the basic graphics of the component packaging.

6. Create a new PCB component editor in Protel 99SE. Open the PCB component editor. After creating a new component. Then select a component package from the Protel 99SE PCB editor and copy it to the PCB component editor for component production.

7. After all component packages are made. These packages are then placed in the Protel 99SE PCB editor. It is then exported as a CAD file.

8. One of the necessary software for PCB reverse engineering is AUTO CAD. After opening the CAD file of the component package diagram. Then the CAD file that imported the PCB picture before is also opened. And copy the component package diagram to the CAD with PCB picture. At this point, the CAD file with only component package drawings can be closed. Just work in the CAD file with the PCB picture, according to the Angle and position of the components of the PCB diagram. Arrange the components one by one, taking care to copy and paste more child components.

9. Placement pad and vias: After placing the component package. The next work is to place the pads and vias. First measure the inner diameter and outer diameter of the pad in CAD. In the drawing menu, select the circle subitem. And determine the inner and outer diameters of the ring. When placing pads, the pads of the same size should be placed in one time. However, quad pads and polygonal pads cannot be placed. Although in CAD can be used to fill polygons into solid methods. But the filled entity will only have an empty border when transferred to Protel 99SE. Therefore, if there are polygonal pads in the PCB drawing, we can trace the edge of the pads with lines. Transfer to Protel 99SE and place the corresponding pad.

10. Draw traces: Once the pad is drawn, start drawing traces. Drawing traces is done using aggregate lines. In the Drawing menu, select the aggregation line. Determine the start and end widths of the aggregation line, and then start drawing. In the process of drawing, if it is a straight line, you have to choose the orthogonal line. If it's 45 degrees or whatever, you have to cancel the orthogonal line. If the width of the midline of the entire circuit board is only a few specifications, we can also use ordinary lines to draw. However, different layers will be used for different line widths. Go to Protel 99SE and edit the line width.

11. When the tracing is finished, we do the last piece of work in CAD. Place silk screen, if it is text, use the method of placing text box to achieve. If it is some irregular silk screen lines, use the aggregate line, of course, you also use direct lines to draw. Go to Protel 99SE and edit the line width.

12. After the above steps, we have basically completed the work in CAD. If you do not transfer to Protel 99SE, you can also hand over to the PCB dealer to help you make the board. You can also print out the layers you need and make your own PCB. Of course, my ultimate goal in writing this article is to inform readers. To transfer the drawing into Protel 99SE, we have to proceed with the following steps.

13. Open Protel 99SEPCB editor. Import the CAD file you have traced. Note that in the dialog box of the import file, the CAD layer should be corresponding to the Protel 99SE layer. This is important, regardless of the name of your layer in CAD. But you must know what layer this layer corresponds to in PORTEL99. If you do not, you will spend more time in PORTEL 99 layer conversion. It's also a good idea to change the default line width when importing.

14. Finally edit, after importing Protel 99SE. Make appropriate edits as well. For example, when we import, we put both wires and pads on TOP LAYER. At this point you should place all pads in the MULti LAVER layer. There is no matter what Angle you put the silk screen text in CAD. Go to Protel 99SE and it's all positive. At this point you have to adjust against the physical PCB.

15. If there are lines or screen prints on the other side. Just do it as above. Then import into Protel 99SE for integration. Be careful to mirror. Finally, check carefully against the picture or PCB. You can also make the appropriate changes and you're done.
From the above detailed PCB reverse engineering process, we can see the relationship between the two important software we use.

PCB reverse engineering considerations:

In CAD if you accidentally move the picture. Then all the lines you drew will be lost. At this point, remove the image altogether. Then you will draw all the lines selected, and then move to the picture on the line, pay attention to the object tracking and object lock point, so that it can be set very accurate. 

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