Thermal Strain Measurements in Electronic Packages Through Fractional Fringe Moire´ Interferometry

Fractional Fringe Moire´ Interferometry (FFMI)—a new experimental methodology to measure accurately deformations and consequently strains—has been successfully implemented to determine thermally induced strains in a specimen made from an AT&T 1MB DRAM device. The specimen was heated uniformly from room temperature to 90° C. Resulting moire´ fringe patterns were recorded, analyzed using digital-image-processing and in plane displacements in the device were determined. Strain components were computed by simple differentiation of the displacement fields. The technique proved to be successful in detecting full displacement fields with submicron resolution. Contour maps showing actual thermo/mechanical strain components in the specimen were constructed. Those maps can provide an excellent tool realistic for strain analysis of microelectronic devices regardless of the structural and material complexity.