Abstract-Effects of Bi addition to the Ag-containing leadfree solders have been the focus of a considerable amount of past investigations, however, influence of Bi on Sn-Cu-Ni system has not been studied so extensively. In the present study we aimed to reveal the influence of Bi on microstructure formation of Sn-0.7Cu-0.05Ni/Cu solder joints both in the bulk and at the interface. It is shown that (i) Sn-0.7Cu-0.05Ni solidifies to produce a markedly different grain structure to Ag-containing lead-free alloys; (ii) Bi additions to Sn-0.7Cu-0.05Ni had no discernible effect neither on the βSn grain structure nor on (Cu,Ni)6Sn5 interfacial intermetallic layers or primary intermetallic crystals in solder joints.