Fast and accurate method for flaws localization in stacked die packages from acoustic microscopy echoes transients

The scanning acoustic microscopy (SAM) is widely used today by the manufacturers and researchers in failure analysis labs to improve the microelectronic devices reliability. The goal is to detect and locate flaws inside chips using non destructive test (NDT). New packaging technologies improve the number of layers in a single package using advancing formats including for example flip chip, ball grid array and thereby increasing the number of interfaces to study. This paper deals with the automatic detection of small flaws in the z-axis to reduce time of experiment and facilitate the localization of the flaws especially in solder bump joints and underfill.