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Mechanical characterization of lead-free solders in FCIP devices

: Krause, M.; Petzold, M.; Grau, P.

SURFACE, Hückelhoven:
NANOMECH, 6th European Symposium on Nano-Mechanical Testing 2005 : 30.08.2005 to 01.09.2001
Hückelhoven, 2005
European Symposium on Nano-Mechanical Testing (NANOMECH) <6, 2005, Hückelhoven>
Fraunhofer IWM ()
lead-free solder; nanoindentation; Pop-In

Restrictions on the use of lead-containing materials in microelectronical products are confronting the microelectronics industry with the demand for lead-free alternatives for solder interconnects. In this study we investigated the potential of nanoindentation techniques in combination with scanning electron microscopy (SEM) and atomic force microscopy (AFM) for the local mechanical material characterization of a lead free SnAg3.5Cu0.7 solder material in FCIP devices. The derived results show that the data evaluation has to consider the well known pop-in phenomenon whereas no significant dependence on the presence of precipitated Ag particles in the solder was found. In addition, the pronounced creep deformation properties of the solder have to be taken into account and could be adequately quantified. Furthermore measurement routines for the intermetallic compounds in the interfaces between solder and chip/board metallization were derived. It is shown that multiple reflows do not significantly affect the indentation results compared to soldering kinetics and material composition. The results are discussed in terms of the solder microstructure and compared to results derived from literature.