Research on Indentation Creep Property of Sn-3.5Ag-2Bi-0.7Cu Lead-Free Solder

Abstract:

The indentation creep behaviour of Sn-3.5Ag-2Bi-0.7Cu lead-free solder was studied in the temperature range of 50-100 ℃ and indentation stress range of 16.7-43.2 MPa. The stress exponent n of 3.181, creep activation energy Q of 59.189 kJ/mol, and material structural constant A of 0.423 were obtained. The constitutive equation of the steady state indentation creep rate of the Sn-3.5Ag-2Bi-0.7Cu lead-free solder was =0.423σ3.181exp(–59189/RT). The experiment shows that the indentation creep rate increased dramatically as the temperature and stress increased. The Ag3Sn and Cu6Sn5 phases became coarser and shorter after indentation creep, which could increase indentation creep resisting property by strengthening β-Sn matrix.

Key words:Sn-3.5Ag-2Bi-0.7Cu; lead-free solder; indentation creep; stress exponent; activation energy