Thermal Microscopes

The growing density of integration in new electronic designs means that heat from power loss is continually increasing. Another reason for the need for infrared microscope optics is ongoing miniaturization, which can reduce the effectiveness of heat dissipation. Applications that carry higher currents are becoming more common, particularly in drive technology, thanks to power electronics.

The lifespan of semiconductor elements depends heavily on temperature. A 10 °C increase in temperature can reduce lifespan by 50%. This places a challenge on developers of electronic assemblies, who must consider the thermal behavior of circuit boards and assemblies. The best way to measure the temperatures of semiconductors, printed circuit boards, or entire assemblies is through infrared technology. This method is quick, precise, and contact-free, which is especially important in electronics manufacturing. When measuring, it’s essential to check where a circuit board shows temperature variations. It’s also vital to ensure measurements are taken on high-emissivity surfaces, such as Teflon, Polyimide, fiberglass, and ceramics, rather than on metal surfaces that reflect infrared energy.

Several factors can cause excessive temperatures, such as defective components, incorrectly sized circuit paths, or poorly soldered joints. To accurately record the temperatures of tiny components and structures on a circuit board, a high-resolution infrared camera with microscope optics aimed at small targets is necessary. With the right camera and optics, you can clearly see which component on a printed circuit board exceeds its operating temperature.

Optris thermal microscopes open up a level of insight that conventional thermal cameras and optical microscopes simply cannot offer. By combining high-resolution uncooled infrared detectors with precision microscope optics, these systems resolve structures down to just a few micrometers while still delivering calibrated, radiometric temperature data. Every pixel in the image effectively acts as an infrared thermometer, turning tiny solder joints, semiconductor structures, and micro-mechanical parts into clearly mapped temperature profiles instead of vague hot-spot blobs.

It’s equally important to know when the thermal camera can accurately resolve a small component. Just because you can see on the thermal image where a lead connects to an integrated circuit doesn’t mean you can measure the temperature accurately. The infrared industry uses pixel size to indicate the resolving power of an infrared camera or microscope setup. However, a single pixel cannot capture all the radiant heat from a surface the size of a pixel, resulting in a lower temperature reading. Normally, a matrix of 3 x 3 pixels on the target is needed to provide an accurate temperature measurement according to the thermal camera’s specifications. If temperature is crucial, which it often is for electronic components, don’t rely solely on pixel size. Measurement Field of View (MFOV) is the key parameter that defines the size of the target that can be measured accurately.

For electronics, semiconductor, and materials laboratories, this means clearer answers in less time. Localized hot spots on ICs, power devices, and PCBs can be easily pinpointed, compared, and documented under realistic operating conditions. Subtle temperature gradients around bond wires, vias, or micro-cracks show up immediately, helping to validate designs, troubleshoot failures, and verify thermal models. Because the thermal microscopes are non-contact, sensitive structures stay intact and undisturbed throughout testing.

Infrared cameras have typically been used for design validation, but research is ongoing to incorporate Optris infrared cameras into the production phase of the reflow process. This integration aims to validate the temperature of the board and its components as they move through the oven. Optris PIX Connect software operates in line scan mode to collect temperature data along a single line through a small slit in the oven. The software converts this data from a single line into a complete thermal image of the board, using the board’s motion through the thermal camera’s field of view to reconstruct the vertical dimension. This research and other similar efforts aim to expand the use of infrared camera technology in the electronics field.