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2021 Update I How to Check and Inspect a PCB or PCBA

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Wed, Oct 30, 2019

Will you meet any problems when you received your PCB boards? 

It is very important to control the quality in PCB, because a problem may cause the board to be scrapped.

Therefore, it is very necessary to inspect the circuit board carefully. The following contents from PCBONLINE will help your current problems about how to check a printed circuit board.


How to Check a Printed Circuit Board.jpg

 When it comes to testing the quality of printed circuit boards, there are several strategies for your reference:

1.) Naked eye Plus magnifying glass check

At the beginning of the inspection, the problems we may find with naked eyes include cracks, irregular surfaces, incomplete circuits, and loose components such as resistors, capacitors, diodes, insulation layer peeling, etc.

But these may not be obvious in appearance, so we can use some lighting equipment and magnifying glass at the beginning of the inspection to help us observe the details of the circuit board or components.

2.) Heat inspection method

In some cases, the printed circuit board may "look" normal, but there are potential problems.

How to check PCB to solve this problem? The most common is by heating. Because these invisible damages usually lead to overheating of other components.

Therefore, in order to determine whether the circuit board is damaged, we only need to touch the surface of the printed circuit board, which is usually the surface of components such as resistors and capacitors. 

Components with higher temperatures mean that they may be potentially damaged and need to be removed and replaced.

Note
Please note that although this is a good method to detect any potential defects on the printed circuit board, it is not very safe. It is suggested that this method should only be used to test those devices with low power of electricity.

In addition, we can also use thermal imaging cameras or similar equipment for inspection, but the disadvantage is that the cost is relatively high.

3.) Checking the Other Components

By the way, if you are not familiar with the PCB assembly test you need to know about it first.

If in case one is checking a printed circuit board for damages, there is every chance that the real problem may not be with the circuit board.

On the contrary, the issue might actually have more to do with the other components in the device or gadget. In order to rule out the possibility that there is an issue with these other components of the device, it would be necessary to check them as well, in addition to that of the printed circuit board.

This may seem like a rather time-consuming activity, but it is something that is absolutely necessary if one wishes to find out the root cause of the issue on hand.

Test the Capacitors

This step applies to any printed circuit boards which have capacitors as part of their design architecture.

A capacitor can be defined as a component that allows for alternating current to pass through it. This is something that is rather common in many of the printed circuit boards around.

The way to test a capacitor is to discharge it by touching its leads together.

Once this is done, they are to be tested with a voltmeter, with the resistance at its highest possible setting. The capacitor is to be probed with the power off and then again with the power back on; 

Should the meter reading be zero, it is an indication that there are issues with the capacitor.

Test the Resistance Points

Resistors are small components that control the flow of current through a printed circuit board.

To test whether the resistors are functioning as intended, one needs to begin by disconnecting any power supply that is connected to the circuit.

Turning on the power, a voltmeter is to be placed on the circuit directly at the first resistor. This can be done by 'tracing' the circuit path. 

One will need to check whether there is any voltage flowing through the circuit, which will be indicated by reading in the voltmeter;

A reading of zero is an indication that there are issues with the resistors.

Typically, your average printed circuit board will comprise several different resistors, spread out across the board. 

This means that one will have to follow the above step for all of the resistors that exist on the circuit board in the exact same way.

Conclusion

It should be added that there are several other details as well when it comes to checking the functioning of a printed circuit board. The above are but some of the most important and indeed, standard ways in which the same is done across the industry level.

Depending on the needs and requirements, there is a chance that the same will vary in some cases.