Adherence and delamination with ultrasound ...

Acoustic microscopy (SAM) is a non-invasive & non-destructive technique that can be used to image the internal features of a specimen, in particular its interfaces. SAM is a superior tool to detect delaminations even of sub-micron thicknesses (down to 100nm !). SAM is particularly useful for inspection of small or complex optical devices, electronic devices. SAM can also be used to measure the thickness of an internal layer of material.  Overall, SAM is an efficient tool for evaluating sealing quality, printed circuit boards, underfills, BGA, QFN, passive components, and wafers.

 

SAM systems use sound energy to image a sample through the use of transducers. Samples are submerged in a liquid medium to ensure the ultrasound waves propagate to and through the samples. The ultrasonic transducers send pulses into the liquid. The transducer also receives reflected pulses (echoes) from discontinuities and disturbances from the sample. The transducer transforms the reflected sound pulses into electromagnetic pulses which are displayed as pixels with defined gray values thereby creating an image.

A complementary imaging technology is acoustic Tomographiy (SALI). It allows to slice a sample into as many as 100 images using a single scan. The image data set allows to investigate different interfaces.

 

Example of Lead-Frame delamination (aging tests)

The use of ultrasonic technologies makes it possible to detect and study:

  • Interface issues (eg: delamination)
  • Material issues (eg: cracks)

 

Applications :

-          Fast production control

-          Standards : IPC A610, Mil-Std883, J-Std-035, Esa, etc

-          Parts sorting

-          Inspection of solder pads, flip-chip, underfill, die-attach

-          Sealing joints

-          Brazed and welded joints

-          Qualification and fast selection of glues, adhesive, comparative analyses of aging, etc

-          Inclusions, heterogeneities, porosities, cracks in material

Fields :

-          Electronic

-          Medical

-          Metallurgy

-          Optics and optronic

-          Mechanical parts

-          Switching contacts (switchgear, relays, contactors)

-          jewelry, watchmaking

-          Composite, ceramics, plastics

-          R&D