First-principles calculations on physical properties of Ni3Snx binary system intermetallic compounds and Ni/Ni3Sn interfaces in Nickel-Tin TLPS bonding layer

Physical properties of Ni3Snx intermetallic compounds as well as the interfacial properties of Ni/Ni3Sn interface were investigated by first-principles calculations for studying the crack initiation behavior and mechanism of the novel Nickel-Tin TLPS bonding layer. The results indicated that, for Ni and Ni3Snx intermetallic compounds, Ni3Sn4 intermetallic compound shows the smallest deformation resistance, the largest brittleness and strongest micro-cracks initiation tendency because of the largest average bond length, the biggest crystal asymmetry and the most complex bonding characteristic, so it will be cracking preferentially in all of the Ni3Snx intermetallic compounds under the stress condition. For the Ni/Ni3Sn interfaces, Ni (111)/Ni3Sn (111) interface with OT stacking sequence shows the weakest interfacial bonding strength with adhesion energy of 3.11 J/m(2), and it will crack at layer 1'-1 with only 12% imposed strain, so it can be considered as the weakest interface under the stress condition in all of the Ni/Ni3Sn interfaces.