Stabilization of hexagonal Cu6(Sn,Zn)5 by minor Zn doping of Sn-based solder joints

The influence of Ni and Zn additions on microstructure and phase transformations in Sn–0.7Cu/Cu solder joints

“…Ni is not the only element to stabilize the g-Cu 6 Sn 5 structure. Zn, Au, In and Sb have all been confirmed to stabilize hexagonal Cu 6 Sn 5 [52,53]. Over the entire range of À80-240°C, different levels of Zn and Au and 7.1 at.% In can stabilize the hexagonal g-Cu 6 Sn 5 structure and avoid the polymorphic phase transformation to g 4+1 [10,11,54].…”

Growth mechanisms of interfacial intermetallic compounds in Sn/Cu–Zn solder joints during aging

“…In Sn/Cu15Zn and Sn/Cu-30Zn solder joints, Cu and Zn atoms dissolved from the Cu-Zn substrates into the liquid solder, reacting with Sn to form scalloped-type Cu 6 (Sn,Zn) 5 . It was reported that minor Zn dissolving into the Cu 6 (Sn,Zn) 5 IMC can stabilize the hexagonal structure during thermal aging [14]. Thermal aging induced the growth of interfacial IMCs.…”

Suppressing the growth of Cu–Sn intermetallic compounds in Ni/Sn–Ag–Cu/Cu–Zn solder joints during thermal aging

“…The Cu 6 Sn 5 -based IMC with Ni and Zn is represented as L-(Cu,Ni) 6 (Sn,Zn) 5 . Literature indicated that the minor Zn doping into Cu 6 (Sn,Zn) 5 can decrease the Gibbs free energy and stabilize the hexagonal structure [22]. In contrast, few Zn atoms dissolved into the high Ni-contained H-(Cu,Ni) 6 Sn 5 IMC.…”

“…It is inferred that the Zn dissolving into L-(Cu,Ni) 6 (Sn,Zn) 5 restrained the Ni diffusion into L-(Cu,Ni) 6 (Sn,Zn) 5 . Literature pointed out that Zn or Ni atoms doping into Cu 6 Sn 5 can shrink the lattice volume [18,22]. As Zn and Ni atoms coexist in the L-(Cu,Ni) 6 (Sn,Zn) 5 , the solubility of Zn and Ni should be mutually interfered owing to the steric hindrance in the lattice.…”