A robust scheme of moire' interferometry for real-time observation of thermal deformations is proposed. The scheme is implemented with an environmental chamber that produces a temperature profile in an accelerated thermal cycling condition. Vibrations caused by the environmental chamber are tolerated by forcing the specimen and the optical system to vibrate in unison. The method is employed to study non-linear thermomechanical behavior of ceramic ball grid array package assembly. In spite of the high amplitude of excessive vibration produced by the oven, which is considerably higher than the submicron displacement sensitivity of moire' interferometry, the proposed approach produces exceptionally stable fringes with high signal-to-noise ratio. Detailed global and local deformations of the assembly are investigated and the implications on an optimum thermal testing condition are discussed.
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