Characterization of mechanical properties of bulk lead-free solders

The drive to reduce the level of use of hazardous materials such as lead has led to the development of many types of lead-free solder material. In this work, one of the most fundamental mechanical properties-tensile behavior-of tin-based bulk alloys used for lead-free solder has been studied. Tensile exposure under various conditions of temperatures and strain rates were carried out on Sn-3.5Ag, Sn-3.4Ag-4.8Bi, Sn-0.7Cu, Sn4.0Ag-0.5Cu and Sn-37Pb bulk samples. Evaluation of the test results shows that generally these tin-based lead-free materials have better ultimate tensile strengths than Sn-37Pb, except Sn-0.7Cu, although in some cases this is not necessarily a disadvantage. Sn-3.4Ag-4.8Bi shows the best strength among the alloys due to the solid solution strengthening of fine bismuth particles from room temperature to 150°C. The effect of strain rate has also played an important role in the behavior of tensile strength; a trend for strain hardening to decrease with increasing the strain rate is clearly seen