How To Convert A PCB Into A Schematic

 
Converting a printed circuit board back into a schematic is essential, especially if you are looking to improve or add functionality to an existing product. The PCB to schematic process is a delicate procedure that requires finesse, patience, and determination, but it is not an overly complicated process as some might believe it to be so. Here is a brief, simple, and step-by-step guide to obtain a schematic from a printed circuit board.

1. Take a Picture

Using a professional digital camera, take a high quality image of the PCB under adequate light. Then you can use a photo editing software like Inkscape or GIMP to make the picture clear. It is important that the picture is cleared of any blemishes, blurs, or distractions.

2. Filter the Holes

After the picture is cleared, the next step is to identify the holes of the PCB. The holes are the points where the pads of the solder are situated; identification and removal of the holes is crucial to success. You can use a color filter or paint them in the software.
For example, if you want to see the holes in a PCB with a green solder mask, you can get rid of the green and blue channels through the program.

3. Eliminate the Ground Plane Holes

Certain software programs can convert the holes of the PCB into small loops by leaving a track. These loops are easily identifiable and can be circled. Known as ground plane holes, they have to be removed for a successful conversion of the PCB to a schematic.

4. Make the Tracks Visible

In order to see through the painted layer of the PCB, adjust the luminosity setting until the tracks become visible. In a PCB, the tracks are the copper conducting paths between the different electronic components. If you observe that the tracks have rough edges, smooth them out.

5. Turn the Image into Grayscale

The colors of the image have to be inverted, in others it has to be converted into a grayscale or black and white image. Additionally, any further distortions should be eliminated from the background. Ideally, the final image should have dark tracks on a lighter background.

6. Convert the Image into a Vector

You have to use a special photo editing software to convert the image into a vector based drawing. For example, a good program is AutoTrace. In a vector based drawing, the lines can be moved about and connected with one another.

7. Make a Picture of the Components

The empty substrate layer has to be filled at a later stage, and in order to do so, you have to take a high quality picture of the electronic components. The substrate layer can be painted to see the tracks and the components clearly. Then the components have to be separated as an individual image and their respective symbols should be inserted.

8. Rearrange the Drawing

The vector lines should be rearranged to get the most appealing schematic from a PCB. Therefore, any cheap custom PCB can be easily converted into a schematic.