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3D package technologies like Multi-Chip Modules (MCM) and System in Package (SIP) have been in the semiconductor package industry for some time now. At the advent these technologies were mostly incorporated for digital solutions, however more recently these packaged solutions have been increasingly used for analog technologies specifically for power applications. With these packaged innovations increasingly adapted, Failure Analysis (FA) takes a central stage not just in supporting customer returned devices but also in root cause investigations leading to new product development, qualifications and ramp to market. These 3D heterogeneous packages however pose multiple newer challenges to FA compared to traditional single chip package solutions. This paper presents some of these Failure Analysis challenges encountered most commonly on analog 3D power modules and talks about possible solutions to overcome them with case studies. Further it also addresses solution that will require FA to think and adapt improved tool sets whether it’s newer solutions that market has to offer or modification to existing approach including chemical recipes, decapsulation methods, etc. to navigate these intricate packages.

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In recent years optical time domain reflectometer (OTDR)-based techniques have become a known practice for measuring chromatic dispersion (CD) distribution along an optical fiber transmission link. In this paper, a measurement technique which uses a four-wavelength bidirectional OTDR to evaluate the CD distribution along the length of an optical fiber transmission system has been presented. A novel formulation has been developed for this nondestructive technique to improve the correction factor, which leads to an improvement in the CD and mode field diameter (MFD) measurement. The obtained experimental outcomes are in good agreement with those obtained by the interferometric technique.