Acoustic microscopes pulse ultrasound into a sample and use the return echoes to find and image cracks, delaminations, and other gap-type flaws in manufactured parts and products. New developments in microscope technology enable mapping of the point-by-point contour of tilted or warped interfaces, as well as individual material layer thicknesses. This article includes an example of mapping of buried layers in power insulated gate bipolar transistor modules used in railroad engines, heavy mining equipment, and electric automobiles.

Physical cross-sectioning is commonly used on parts to reveal and study their internal features and defects. An alternative technology, acoustic cross-sectioning, produces equivalent results and images for small parts without damaging them. This article describes a new system for acoustic cross-sectioning and presents a case study of its use in integrated circuit analysis.

Acoustic microscopy is an effective method for detecting voids in plastic-encapsulated microcircuit (PEM) packages.

A new acoustic imaging technique provides a precise, nondestructive view of structural features in the interface region between an aluminum substrate and an open-cell metal foam. It also provides insight into the dynamics of the bonding process and the formation of voids.

Acoustic microimaging has advanced over the past few years in response to the growing use of thinner silicon die and innovative packaging designs. This article reviews the basic principles of acoustic imaging technology and describes some of the applications made possible by improvements in spatial resolution, focal length, F-number, and water couplant temperature control. It also discusses common imaging challenges and explains how they can be resolved.