Author(s): X.Y.Pang 1), Z.Q.Liu 1), S.Q.Wang 1) and J.K.Shang 1, 2) 1) Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China 2) Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, IL 61801, USA
Pages: 1057-1062
Year: 2010 Issue:  12
Journal: Journal of Materials Science & Technology
Keyword:  First-principles calculation; Segregation; Bismuth; Interface; SnBi solder;
Abstract: Density functional theory was employed to investigate the bismuth segregation at Cu/Cu3Sn(010) interface.Five initial constructions were introduced by adopting the adhesion energy criterion.Among them,the so-called "between-Cu" construction in which the interface Cu atoms of Cu slab locate along Cu-Cu bond direction in Cu3Sn slab was found to be the most energy-favored at an adhesion energy of 1.96J/m2.Based on this construction,five possible segregation sites were examined,and the most likely segregation site was determined with adhesion energy as low as1.06J/m2,which was almost half of the initial one.Comparing with other sites adhesion energies,it was concluded that size effect took a large part in embrittlement.The analyses of atomic structure and electronic density revealed that the slabs shifted away from interfaces due to bismuth segregation,and the atoms around Bi atom were pressed away.This calculated work agreed qualitatively with reported experimental results.