C-MODE ACOUSTIC MICROSCOPY APPLIED TO INTEGRATED-CIRCUIT PACKAGE INSPECTION

A C-mode acoustic microscope, or C-AM, is hybrid of a conventional C-scan recorder and the Stanford scanning acoustic microscope (SAM). C-AM is a reflection acoustic technique with precision scanning for microscopic inspection, sophisticated signal analysis and display and a broad-band acoustic transducer with a small numerical aperture for sub-surface imaging. The technique offers significant advantages for the nondestructive inspection of integrated circuit (IC) packages. C-AM provides 3-D information on structures and defects within the IC package. Phase analysis of the echo signal helps in the identification of delaminations and package cracks. The nondestructive nature of C-AM inspection and the sensitivity of the technique to important package defects facilitate the study of the moisture sensitivity problem in surface mount plastic packaging.