How Do I Trace The Path Of A PCB?

Image source Freepik

A printed circuit board comprises electronic components that are arranged on the semiconductor material. These components are linked or connected to each other via traces. We can define a PCB trace as a thin line, usually made of copper material, that provides a pathway for the flow of electric signals on the PCB. Copper is an ideal material because it is a good conductor of electric signals or currents.

There are several circumstances or scenarios that will push you to work on the PCB. Maybe you would like to repair a component or just inspect it. To do so, you will have to trace the path of the signal flow. Where is the source of the path and where does it stop? How many branches does the path have and which components are directly connected to the PCB path? In this article, we are going to discuss the most effective way of tracing the PCB path.

Steps for tracing PCB path

Here are the steps and actions that you should take when tracing the path of a PCB.

1. Mark your starting point: the very first step of the process entails identifying the starting point of the path. This is the point that will give you a clear direction of where to go when tracing the path. The point could be an electronic component such as a resistor or it can be a chip. You may consider using a circuit diagram for easy identification of the PCB path. An alternative way of identifying the right path is by marking the input and output points on the PCB. From there, it will be easy to identify the movement of the path.
2. Use an oscilloscope: A this point we assume that you have identified and even marked the starting points of the PCB path. It will give you a magnified view of the path that is taken by the PCB trace. Switch on the oscilloscope and insert the probe into Channel 1 of the oscilloscopeso that you can have a clear view of the input terminal.
3. Find the ground point on the PCB and connect it to the ground socket of the oscilloscope.
4. Connect the PCB terminals to a power source and switch it on.
5. Using the probes of an oscilloscope, touch the starting point of the PCB. You can do this using the tip of the probe. While the tip is still at the starting point of the PCB, press its reset button. Take note of all the parameters of the oscilloscope while the tip of the probe is still at the starting point.
6. Now visually try to follow the trace or the path as displayed in the oscilloscope. The path starts from the starting point on which you have placed the probe of your oscilloscope.
7. Position the probe on the first PCB component that you encounter on the path. You should be able to see waves or pulses on the display unit of the oscilloscope. This is an indication that the current is flowing through that component.

On the other hand, if you don’t see any pulses even after placing the probe on the component means that there is no current or signal flowing through the component. This is an indication of a broken path. At this point, you should start backtracking to find out if the path could have been broken somewhere before the specific electronic component.  If you do this correctly, you will be able to identify this point and maybe make necessary corrections

8. If the component gives an indication of the presence of electric signals, you should be free to proceed to the next component on the copper trace up to the end of the path. Of course, you should always confirm the results on the oscilloscope with each touch of the probe on the component.

Using an oscilloscope to find the path of PCB. Source Freepik

Once you follow the eight steps we have discussed, you will be able to trace the path of the PCB.  The most important skill and knowledge that you should use is knowing how to use an oscilloscope. You should also be keen when it comes to reading data on the oscilloscope.

PCB path characteristics you should know

After tracing the path of PCB, what next? It is important to take note of the key features and characteristics of the path. The data will help you know the behavior of the path and you may also come up with ways of improving various parameters of the path since they are directly affected by the flow of signals.

Here are some of the important properties of PCB path that you should know:

• PCB return path: This is the path that the signals take when they are returning to the source. The return path usually ends up forming a complete loop.
• PCB path width: Path width refers to the width of the copper trace that makes up the path. The path width is usually determined when designing a printed circuit board. It has an impact on the signal integrity and thermal management of the printed circuit board. For example, a thicker path width prevents incidences of overheating.
• Trace path length: This is the total distance that is covered by the PCB path.  Usually, it depends on the layout of the PCB and the number of components.
• PCB trace resistance: Trace resistance is the level of opposition to the flow of electric current on the PCB path. Technically, any path should have some resistance. However, PCB manufacturers strive to keep it to the lowest level. High resistance is likely to cause overheating and also increase the rate of energy consumption by the PCB.
• PCB trace current:  How much current can the path support without overheating or affecting data integrity? You should not allow more current than what the trace can support.

Final thoughts

I hope that at this point you know what it takes to trace the path of a printed circuit board. As long as you have an oscilloscope, the rest of the procedures will be easy to follow. In case have any questions about buying PCBs in China, it is advisable to consult experts in this field.

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