Abstract:

Precise estimation of thermo-mechanical properties of single-crystals and grains boundaries is necessary for grain-scale modelling of oligocrystalline solder joints, which are common in modern-day microelectronic packages and assemblies. In this paper, monotonic creep tests are conducted on single crystal SAC305 solder joints at 25 and 125 °C with load between 20-30MPa. Cross-polarized microscopy was used to confirm that the solder joint had single grain. Experimental setup was updated for direct measurement of solder deformation and calibration methodology of measurement system was presented. New experimental results are presented for tensile creep of single crystal solder joints of sufficiently high aspect ratio to be representative of quad-flat-no-lead (QFN) packages and leadless chip carrier (LCC) packages. Room temperature test sample did not rupture under given load. High temperature testing revealed cracking in the solder joint. Effect of change in temperature and load on creep behavior of solder joint is presented. Experimental results and failure analysis (including EBSD assessment of grain orientation) will be used in calibration of crystal viscoplastic (CV) and continuum constitutive models across a range of temperatures.

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