Of all the various failure analysis techniques, microthermography is perhaps the most important. If we could do away with all procedures and retain just one which can tell us the most about a chip, we'd like to see the thermal output and which areas are misbehaving. Because of this, there is more than one technique to get the "heat map" of a chip and last week we saw how liquid crystals can be used for this purpose. But liquid crystals suffer from some major flaws and recently, failure analysis using fluorescent microthermal imaging (FMI) is coming to the fore as a compliment. In this article, we see why FMI is important, how it works, and how it's used.