Study of Phase Shift of Lock-In Thermography and Its Application in 2.5D IC Package

In this study we demonstrate the use of phase shift of lock-in thermography (LIT) a powerful technique in characterizing the Z profile of 2.5D packages. It is interesting to have a good understanding of how a given package structure correlates with LIT phase shift. We create a short defect to validate the experimental phase model and the approach would be useful in applying to other type of 2.5D lCs.