Temperature-dependent fatigue modeling of a novel Ni, Bi, Sb containing
Sn-3.8Ag-0.7Cu lead-free solder alloy
Abstract
Low-cycle fatigue testing of a lead-free solder (InnoLot) based on
Sn-3.8Ag-0.7Cu (SAC387) with three simultaneous additions of bismuth,
nickel and antimony was conducted using miniature-sized fatigue
specimens at different temperatures and strain amplitudes. The
experiments show a decline of the load capacity of the solder alloy with
the number of loading cycles. The fatigue life of the solder is also
decreased by the level of imposed temperature. The modified
Coffin-Manson and Morrow models were used to analyze the behavior under
fatigue and predict lifetime. The parameters in the two fatigue models
which were determined by considering different temperatures and total
strain amplitudes. Compared to other reference lead-free solders, the
InnoLot solder shows much better fatigue strength. The better fatigue
strength is found to result from the effect of BiNiSb elements. Also,
lifetime predictions were made with both models for the solder alloy
under different conditions.