Based on the investigations described in the
present work, several conclusions may be offered
regarding a comparative evaluation of microstructural
and mechanical deformation behavior of SAC
solders containing 0.05Ni:
(1) Adding 0.05Ni element into SAC solders generated
mainly small rod-shaped (Cu,Ni)6Sn5 IMCs
inside the b-Sn phase. In addition, increasing Ag
content affects the size and shapes of IMCs
precipitate.
(2) A significant improvement was observed in the
mechanical properties of SAC solders with
increasing Ag content and Ni addition. Hence,
the Sn-2.0Ag-0.5Cu-0.5Ni solder showed the
highest tensile strength due to the formation of
(Cu,Ni)6Sn5 IMCs.
(3) The activation energies of lead-free solders were
investigated to be 78.9 kJ/mol for SAC (205),
53.1 kJ/mol for SAC (0505), 93.6 kJ/mol for SAC
(205)-0.05Ni and 72.2 kJ/mol for SAC (0505)-
0.05Ni.
Overall, adding a trace amount of Ni element and
increasing Ag content can improve the properties of
SAC solders. Thus, the effect of Ag content and
element addition on the properties of solder should
be comprehensively considered.