Formation and behavior of Kirkendall voids within intermetallic layers of solder joints

Influence of intermetallic growth on the mechanical properties of Zn–Sn–Cu–Bi/Cu solder joints

“…The vacancy flow and condensation in combination with a state of tensile stress makes it possible for the voids formation. In case there is not enough plastic relaxation during the process, then vacancies will coalesce to form pores or voids in the reaction [23]. In the wetting process, if one of the atoms in a couple diffuses faster than the other one, a vacancy flux will move towards the reverse direction and finally form Kirkendal voids [23,24].…”

“…In case there is not enough plastic relaxation during the process, then vacancies will coalesce to form pores or voids in the reaction [23]. In the wetting process, if one of the atoms in a couple diffuses faster than the other one, a vacancy flux will move towards the reverse direction and finally form Kirkendal voids [23,24]. In the present study, voids were formed with the growth of transient ε-CuZn 4 intermetallic phase at the interface, which has negative effects on the mechanical properties of solder joints.…”

Microstructural and mechanical analysis on Cu–Sn intermetallic micro-joints under isothermal condition

“…For instance, Kirkendall voids are normally found in Cu 3 Sn layer or near the interface between Cu 3 Sn and plated Cu substrate after aging or during the service period [14][15][16], which will strongly impact the reliability of the IMC interconnections.…”

Phase field simulation of Kirkendall voids at the interface of microscale Sn/Cu system lead-free interconnects

“…It has been demonstrated that electromigration and thermal aging have a remarkable effect on the initiation and growth of Kirkendall voids at the interface of solder joints [1][2][3]. It is known that Kirkendall voids are the result of unbalanced atoms diffusion in solid state reaction between solders and under bump metallization (UBM) [4]. However, Kirkendall voids were also found between Cu and the Cu 3 Sn during the soldering process, though the number of voids was very small [3].…”