The Detection and Analysis of Thermally Induced Displacements in Powered Microelectronic Circuits Utilizing Holographic Interferometry.
TEXAS UNIV AT AUSTIN ELECTRONICS RESEARCH CENTER
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A method of producing holograms of microscopic subjects was developed in which a magnifying lens system was introduced into the recording phase. Good quality holograms were realized of three basic types of electronic circuits, namely an integrated circuit, a hybrid microcircuit, and a discrete component circuit. Double exposure holograms were then recorded of each circuit. One exposure was made in an unpowered state followed by a second exposure after power was applied and a thermal equilibrium condition was attained. From each double exposure hologram, vivid low frequency fringe patterns were exhibited during the reconstruction phase. By analyzing these characteristic fringe patterns, displacements to a fraction of a wavelength were observed in the case of the integrated circuit, and several wavelengths of expansion were obtained for the hybrid microcircuit. In addition, the various modes of expansion for each circuit were explained by relating the observed fringe patterns to the circuit geometries and the thermal heating conditions imposed.
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