Acoustic Microscopy Inspection

If you want to examine the internal features of an object without damaging that object, one of the best ways to do so is with scanning acoustic microscopy (SAM), also known as acoustic micro imaging (AMI). This is a non-destructive technique that uses high-frequency sound waves – ultrasound – to generate an image.

Because we perform C-mode scans using technology from Sonoscan, Inc., we use that manufacturer’s well-recognized trademark term for this technique: C-SAM^®.

Simply put, a C-mode scan produces a 2-dimensional image of ultrasound echoes that arise from reflections at a specified depth. Here’s how it works:

A transducer is used to generate a sound wave with a specific frequency chosen for its compatibility with the component or material to be imaged. Typical frequencies are in the 10 MHz to 300 MHz range.

As the sound wave interacts with the component being tested, a portion of that wave is reflected at each interface while another portion of it is transmitted through the interfaces. Both signals – reflected and transmitted – can be used to produce images of the various interfaces present within the component.

C-SAM^® is particularly sensitive to interfacial defects such as air gaps resulting from delamination at the paddle, die, or leadframe, cracks, such as popcorn cracks, and voids. For example, delamination of the mold compound from the surface of the die or leadframe in a PEM creates a very thin air gap at the interface. That thinness isn’t a problem, though: sound waves won’t travel across an air gap, however small. So 100% of the ultrasound signal will be reflected at the delamination, allowing a clear distinction to be made between a good bond and a delaminated bond. The same holds true for any crack or void in an otherwise solid component: the air gaps these defects create will reflect the ultrasound signals and thus be clearly identified.

We use C-SAM^® to scan a wide variety of part types, including PEMs, capacitors, PCBs, and all sorts of hybrid devices. We also use it in a comprehensive range of applications.

When you choose AcousTech for your C-SAM^® inspections, you can expect a test plan customized to your specific needs and clearly communicated in order to assure meaningful results. You can expect a truly collaborative partnership, too. Contact AcousTech if you have any questions. And when you’re ready, Request a Quote. We’re ready to serve you.