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. A close relationship with SONIX, a member of the CALCE, allows CALCE to stay constantly updated on the latest techniques and technologies available in acoustic microscopy. A wide range of transducer frequencies, from 2.25 to 230 MHz, also provides CALCE the capability to conduct SAM on a number of electronic products and components, regardless of the sample thickness or resolution required.

Introduction

Electrical Testing

Destructive Evaluation