MicroDAC strain measurement for electronics packaging structures

Thermo-mechanical reliability concerns in microelectronics and microsystem technology have led to a significant need in information on stress/strain behavior inside microscopic components under load. Because of the decreasing size of structures new measurement tools have to be developed in order to assure future experimental access. Strain measurement from load state micrographs utilizing correlation techniques seems to be one of the promising approaches. Its application to thermally stressed objects in electronics packaging is the main topic of this paper. Deformation measurements are presented for solder interconnects of flip chip and chip scale packages. Emphasis is made for the experimental support of finite element simulation by means of experimental validation of mechanical modeling. Furthermore, a wide variety of new packaging materials and material compounds are to be characterized. Different material properties for bulk material and microscopic structures intensify the search for new testing methods. Again correlation algorithms can be applied to measure strains on microscopic areas and subsequently to obtain material properties. The feasibility to measure coefficients of thermal expansion and Poisson ratios on tiny specimens is demonstrated in the paper.