LIT was used to find a fail in a poly capacitor inside a regulator circuit block with an output switching signal in a 1-channel high brightness LED driver device while the DUT was exercised as shown in Figure 4911a, while PEM was not able to provide conclusive results. The hotspot of the fail indicated by the red arrow was shown in the LIT amplitude image in Figure 4911a.

Figure 4911a. Images of the area on the chip: (a) LIT, and (b) PEM. [1]

This defect, observed in LIT in Figure 4911a (a) and 4911b (b), of the shorted poly capacitor is visible in optical microscopy as shown in Figure 4911b (a).

Figure 4911b. The observed defect: (a) optical and (b) superimposed LIT image. [1]

[1] Paul Hubert P. Llamera and Camille Joyce G. Garcia-Awitan, Thermal Failure Analysis of Functional Failures by IR Lock-in Thermal Emission, ISTFA™ 2019: Conference Proceedings from the 45th, (2019).