Comparative study on tensile creep behavior of SN-9ZN, SN-0.7CU and SN-49ZN-1CU solders

Solder plays an important role in various applications like microelectronic packaging and mechanical joining. Tin-lead solder has been used in electronics assemblies for many years. Its adequate mechanical, electrical and thermal properties, combined with its low material cost, have made it the material of choice for joining active and passive components. However, lead being highly toxic and with the arrival of legislative restriction on the use of leaded solders there arose a need to initiate the search for acceptable, alternate joining materials. In this regard the commercial industries are rapidly implementing lead-free assembly strategies. As a result many binary, ternary and quaternary solder alloys are proposed. Although many of these alloys possess higher strength than traditional solders there still exists reliability problems such as creep. In this paper, an attempt is made to investigate tensile creep behavriour of three lead-free solders. Among the solders studied, Sn-49Zn1Cu solder exhibited better creep resistant behaviour than Sn-0.7Cu and Sn-9Zn solders.