Products > Thermal Imaging

Use of a Thermal Camera for PCBA thermal profiling and repair

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This is a Flir E4 shot of a device with a microprocessor short circuited inside. I connected I believe 1V or 2V from a power  supply with current limited to 200mA or something. The MPU nicely glowed.  :-+

A failed Android cell phone. Did not boot anymore but the battery kept going and something inside was burning.

Another good video from Alex at NorthridgeFIX. Note how useful the thermal imaging capability is to Alex whilst tracking down the source of a short circuit on a laptop motherboard. Injecting a voltage and current limited supply into the shorted supply rail provides the heating of the failed component that is sometimes needed to identify it. Personally I would have used a lower current though ! 7A can damage fine PCB trace. In this case it was a short from a heavy duty PCB trace to ground though so it was relatively safe. Had the short been on a fine, low current, PCB trace the result may have been additional damage though. Care is needed when injecting voltage and current limited supplies into PCB’s. Usually 1A to 2A is more than enough stimulation of a short.

And another good video from Alex at NorthridgeFIX. This time a Dell 15 laptop with a short a long way away from the stressed MOSFET that controls the power rail. As Alex demonstrates, the thermal camera quickly highlights the failure area even though it is on the hidden side of the PCB. My only comment is that I would have repeated the test with the suspect area visible to see whether a failed MLCC was obvious. That said, a failed MLCC can cause the overheating of a component that drives it so some caution is needed before condemning an active component that is getting very hot. Alex chooses to remove the MLCC’s first to cover this possibility and I suspect he has learnt that this is the best approach from his significant repair experience.

Look at the speed with which Alex was able to track down this fault and also note his comments regarding doing this repair without a current injector and thermal camera. Even a cheap, low resolution thermal camera would be better in this case than no thermal camera  ;) I am fortunate to own the Dianyang CA-10 and FLIR ETS320 so PCBA inspection is quick and easy. A handheld thermal camera is useable for PCBA inspection work but the user needs to hold the camera and this can be inconvenient. Consider buying/making a camera holder to keep your hands free. Close up inspection also requires the camera to have a close focus capability or the use of a ZnSe CO2 laser focus supplemental lens as detailed on this forum.

For information, I bought a small Saxophone stand for my FLIR E4 to hold it at an appropriate angle for PCB work. I tended to use my FLIR E60+ camera on a desk tripod though. It may be worth looking at saxophone stands if you require a camera holder for a camera not equipped with a tripod mount point. I attach a picture of such a saxophone stand for information. They are inexpensive and adaptable to meet your needs  :-+ I paid £12 for my stand, as pictured. The head of the camera rests in the Y yoke and it’s handle rests on the lower support. The camera then looks down at an angle onto the workbench and you can position the PCBA in front of it. No hand shake and both hands are free for probing or camera adjustments.


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