Scanning acoustic microscopy (SAM) Scanning acoustic microscopy (SAM) is a non-destructive technique that can be used to image the internal features of a specimen. SAM is highly sensitive to the presence of delaminations, and can detect delaminations of sub-micron thickness, which are difficult to detect using X-ray radiography. SAM is an important tool for detecting popcorn cracking/delamination, die attach voiding, evaluating flip chip underfill integrity, and lid seal integrity in hermetically sealed packages. Ceramic direct bond substrates may be inspected for delamination using SAM. This technique may also be used to determine the thickness of an internal layer of material.
Both delamination/cracking and die attach voiding are assembly related defects that can increase the susceptibility of components to failure in storage or use, although they may not constitute failures by themselves. Delamination and cracking can result in sheared or lifted wirebonds, passivation cracking, metallization shifting, intermittent electrical failures and metallization/bond pad corrosion. Die attach voiding can lead to die cracking, die attach fracture, or thermal runaway due to poor heat dissipation through the die attach.
The images below show the thermomechanical damage on a PQFP sample induced by solder dipping, a technique used as a tin whisker mitigation strategy for tin rich finished parts.
As received part
Solder dipped part
CALCE uses a SONIX Scanning Acoustic Microscope to conduct acoustic microscopy. CALCE consistently stays up to date in the latest failure analysis and non-destructive technologies provided by its members. To this end, CALCE recently received exclusive ODIS software provided by OKOS, which offers a better user interface and newer features to conduct acoustic microscopy. Some of these new features include a more user-friendly interface, better focusing features, and more data gates to easily mark delaminations. A wide range of transducer frequencies, from 2.25 to 230 MHz, provides CALCE the capability to conduct inspection on a number of electronic products and components.