Microstructure and Mechanical Properties Investigation of Lead-free Solder Sn99.3Cu0.7

Abstract

In the late years, environment concerns have attracted more and more attention in many countries, because of pollution from the lead-based solders and its compounds. Many countries are about to ban using of lead-based solders in microelectronic packaging; the lead-free solders will replace the tin-lead (Sn-Pb) eutectic solders. Due to higher melting temperature of most candidate lead-free solders, however, mechanical properties of them have not been available and are poorly understood. Failure of microelectronic components is mostly likely due to the inferior mechanical properties of solder alloys used in microelectronic components packaging and interconnecting. In this study, microstructure and mechanical properties of lead-free solder alloy Sn 99.3Cu0.7 (Ni) are investigated. The paper will compare the mechanical properties of the lead-based and lead-free solder alloys (Sn99.3Cu0.7 (Ni) and 63Sn37Pb). The tensile test of lead-based and lead-free solder alloys (Sn99.3Cu0.7(Ni) and Sn63Pb37) was conducted at room and elevated temperatures; the relevant tensile properties of them were obtained in this paper. Specifically, the tensile strength of this lead-free solder - Sn99.3Cu0.7 (Ni) in 25degC, 50degC, 75degC, 100degC, 125degC was obtained; and it was found that tensile strength of the lead-free solder decreases with increasing test temperature at constant strain rate. The lead-free solder alloy Sn 99.3Cu0.7 (Ni) was found to have favorable mechanical properties and it may be able to replace the lead-based solder alloy such as Sn63Pb37