NDT of electronic packages, MEMs, sensors and materials in 3D to submicron resolution

There is an explosive growth in advanced 3D stacked packages, MEMs and sensors driven by a variety of applications in consumer electronics, aerospace, automotive and medicine. Accurate 3D analysis of their micro and nanostructures, porosity, defects are crucial to predict and correlate thermal-mechanical properties to reliability, performance and the design of next generation products. While conventional imaging modalities such as optical microscopy, SEM with FIB, AFMs have good resolution, they are limited to surface imaging in 2D and require destructive sample preparation to reveal buried structures. Moreover, precise sample sectioning is proving to be challenging with the advent of 3D stacked packages such as large aspect ratio Through Silicon Via (TSV) where via dimensions can be < 5 um diameter × 50 um long or in combed MEMs structures where the sample cannot be physically sectioned or chemically etched without disturbing the actual construction of the device. Existing NDT (non destructive testing) techniques such as X-ray/Neutron radiography, acoustic, eddy current techniques lack the resolution for micro and nano structural characterization. While conventional microCT or nanoCT (micro x-ray computed tomography) have the advantage to be non destructive and provide 3 D imaging, they suffer from poor resolution and contrast especially with large or thick packages and devices. Since resolution is limited to the spot size of the x-ray source, sample size and sample-source working distance, the resolving power of conventional CT is limited to a few microns at best, to several microns being typical, for most packages and sensors.