New methods for scanning ultrasonic microscopy applications for failure analysis of microassembling technologies

Scanning acoustic microscopy (SAM) is now a common detection method which produces high resolution images with focused ultrasonic waves ranging from 10 to 500 MHz. In this paper, first we propose improved methodologies in order to measure time-of-flight (TOF) with high accuracy and so localize defects in depth by digital signal processing used for the study of nonstationary signals as acoustic echoes. Secondly, we compare imaging mode capabilities associated with conventional acoustic focused probe propagation for SAM. Then, we apply these methods for localization of defects and failure analysis of ceramic capacitors, die-attach assembly and solder joint evaluation in a CBGA technology by C-SCAN analysis.