Formation of single phase Cu-Sn IMCs via layer-by-layer electroplating of Cu and Sn metals

The intermetallic compounds, Cu₆Sn₅ and Cu₃Sn, have been prepared via layer-by-layer and single-layer electroplating with subsequent annealing. The two preparation methods were compared in terms of annealing temperature and time, different electroplating effect, and film thickness. Moreover, two copper plates were joined together to form a full-IMC (Cu₆Sn₅ and Cu₃Sn) joint. The shear mechanical property of the IMCs was studied by stretching the plates under different rates. Finally, it was found that the average shear strength of the IMC joints was up to 0.84 MPa when the thickness of the IMC was less than 3 μm. Fracture analysis indicates that the Cu₆Sn₅ lead to cleavage fracture while the Cu₃Sn shows typical intergranular fracture.