See what’s wrong with PCBs
The design of a printed circuit board (PCB) can be complex, sometimes having more than 2,000 components.
What if something is wrong with one of those components? How can you detect tiny faults in PCB components of less than a millimetre that might cause a failure? Very often thermal imaging will be the answer.
European embedded electronics specialist 3T has been using thermal imaging cameras for many years throughout its different activities to detect hot spots of less than 125 microns.
“We are using thermal imaging cameras throughout our entire process,” says Ronald van der Meer, hardware engineer at the firm.
“When something goes wrong in a PCB, be it improper soldering of a circuit or a failing component, the PCB will heat up. Therefore, thermal imaging is a very good way to diagnose PCB boards in an early stage of a problem. We use it in the design phase of a PCB, to test it before it is supplied to the customer or in the qualification stage.”
The company recently opted for the Flir T420 bench test thermal imaging camera with 50μm close-up lens.
“This close-up lens was absolutely necessary, because without it the focus distance was too big,” says Van der Meer. “We are dealing with micro-electronics here at 3T. The mass of the PCB components that we need to research is so little, and possible temperature changes are so small, that we really need that detail.”
The alternative for thermal imaging in the field of PCB electronics is the use of thermocouples, a temperature-measuring device consisting of two wire legs that contact each other at one or more spots.
“Although thermocouple measurements are still required by certain regulatory bodies, the problem with thermocouples for measuring micro-electronics is that these devices can actually disturb the measurement, because they need to make contact with the tiny components on the PCB board,” says Van der Meer. “Thermal imaging on the other hand is a noncontact technology, so you don’t have that problem.”
The T420 is a highperformance thermal imaging camera. It combines excellent ergonomics with high image quality of 320 x 240 pixels. It comes with a tiltable optical unit that makes it possible to measure, and take images of objects at any angle, still in a comfortable working position.
For 3T, Flir’s ResearchIR software for R&D applications was an essential part of the thermal imaging package. ResearchIR allows researchers to make high-speed recordings and perform advanced thermal pattern analysis.
“Sometimes we need to capture the precise response of a one-time thermal event,” says Van der Meer. “This would be difficult to capture in one still image. That is why the ability to make high-speed video images is critical for us.
“Recording a certain event helps us to reconstruct and analyse the problem more accurately. We also import our video images obtained with ReserachIR into MATLAB, a software package for data visualisation, and programming that we use.”
ResearchIR allows the firm’s engineers to better analyse PCB hot spots and find thermal peaks. The software gives users complete colourisation control, so they can change the colour palette, colour distribution, contrast and isotherms, zooming and panning.
The T400 infrared camera.
The FLIR ResearchIR software allows researchers to make high speed recordings and perform advanced thermal pattern analysis.
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The PCB inductor is clearly visible in the thermal image through the PCB’s epoxy layer.
A heated PCB trace.