Measurement strategies

In the following sections some practical aspects of using lock-in thermography in the functional diagnostics of electronic components will be discussed and illustrated by measurement examples of a typical, thermally thin sample (solar cell) and a thermally thick one (integrated circuit). All these discussions are based on the theoretical findings presented in Chap. 4. Section 5.1 discusses the question which of the images available from a lock-in thermography experiment (0∘ image, −90∘ image, amplitude image, phase image, or 0∘/−90∘ image) is most appropriate to display certain details of different heat source distributions. In Sect. 5.2, the influence of the lock-in frequency on the obtained signal amplitude and lateral resolution of the thermograms will be discussed and demonstrated for different heat source geometries. In Sect. 5.3, the influence of a spatially varying IR emissivity will be discussed (emissivity contrast), and different ways to overcome this influence will be introduced and demonstrated. Finally, in Sect. 5.4 a simple technique will be introduced to distinguish Joule type heating from Peltier effects in lock-in thermography experiments on resistive samples.