Crystallographically Faceted Void Formation in the Matrix of Lead-Free Solder Joints

Crystallographically faceted void (CFV) formation in lead-free solder joints has been observed after solidification and during subsequent solid-state aging. Such voids have not previously been reported in the literature. This paper gives a preliminary report on observations of voids which tend to be associated with, and adjacent to, intermetallic compounds in the solder bulk and near-substrate interface region. It has been observed that CFVs are correlated with β-Sn crystallographic orientation and form in a tetragonal shape. Aging promotes CFV clustering and growth.