Summary form only given. A number of plastic encapsulated devices in the as-received condition were screened and documented using SLAM (scanning laser acoustic microscopy). Those parts containing flaws were then examined using a C-SAM (C-mode scanning acoustic microscope) to characterize the type of flaw and depth of the defect. Several of the defect-free parts were also evaluated on the C-SAM to characterize the appearance of typical devices. After the initial investigation, all the devices were thermally shocked. The devices were again screened and documented on SLAM to note any changes from their previous condition. The defective parts were again evaluated and documented on C-SAM to further characterize the defects. Several interesting results were observed from this investigation. In general, a difference in the acoustic properties of the encapsulants was noticed from manufacturer to manufacturer. This may be related to the appearance of defects in certain devices.
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