Using carbon nanotubes to enhance creep performance of lead free solder

In the present study, the influence of multiwalled carbon nanotubes (CNTs) on the creep performance of 95·8Sn–3·5Ag–0·7Cu lead free solder is investigated. Composite solders containing varying weight percentages of CNTs were synthesised. Solder joints were fabricated and subjected to a series of tests under testing temperatures ranging from 25 to 125°C and applied stresses ranging from 4 to 18 MPa. Creep results revealed that solders containing CNTs exhibited significantly improved creep resistance and also creep time to failure increased. Stress exponents of composite solders were higher than that of monolithic solder. In general, stress exponent was found to increase with increasing applied stress and with decreasing testing temperature. The range of activation energies of composite solder with 0·01 wt-%CNT addition was found to be comparable to that of monolithic Sn–Ag–Cu. However, as the amount of CNT increased to 0·04 wt-%, the range of activation energies increased accordingly.