An advanced random phase-shifting algorithm to extract phase distributions from randomly phase-shifted interferograms is proposed. The algorithm is based on a least-squares iterative procedure, but it copes with the limitation of the existing iterative algorithms by separating a frame-to-frame iteration from a pixel-to-pixel iteration. The algorithm provides stable convergence and accurate phase extraction with as few as three interferograms, even when the phase shifts are completely random. The algorithm is simple, fast, and fully automatic. A computer simulation is conducted to prove the concept.

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In the past decade, the optical method called moiré interferometry has matured rapidly to emerge as an invaluable tool, proved by many industrial and scientific applications. It has been applied to numerous problems in engineering mechanics. It measures in-plane displacement fields with high sensitivity and high spatial resolution. This paper reviews current practices of moiré interferometry and its extensions. Applications in diverse fields are addressed to demonstrate the wide applicability of the method, especially the recent applications for thermal deformation analyses of microelectronics devices. Speculation on future developments and practices is presented.

Thermo-mechanical behavior of various levels of electronic packaging products is studied by moire´ and microscopic moire´ interferometry. The global deformations of packages with complex geometries and the local deformations of solder interconnections are determined by displacement measurements of high sensitivity and high spatial resolution. Several packaging studies are reviewed. They include analyses of thin small outline package, leadless chip carrier package, surface mount array package, chip/organic carrier package, deformation near a plated through hole, and determination of an effective CTE. In-situ and quantitative nature of the methods leads to more accurate and realistic understanding of the macro and micro mechanical behavior of packaging assemblies and interconnections, which in turn, facilitates design evaluation and optimization at an early stage of product development.

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We propose an advanced thermal-moisture analogy scheme to cope with the inherent limitations of the existing analogy schemes. The new scheme is based on the experimentally observed unique hygroscopic behavior of polymeric materials used in microelectronics; i.e., the saturated concentration is only a function of relative humidity regardless of temperature. A new analogy formulation based on the modified solubility is presented and the scheme is implemented to investigate its accuracy and applicability. The results from a simple case study corroborate that the advanced scheme can be used effectively for package assemblies subjected to general anisothermal loading conditions.