Eutectic Sn-Bi solder has attracted a great deal of interest since it offers good reliability comparable to that of Sn-Pb solders. Additionally, the increasing need for low cost manufacturing processes, particularly in consumer electronics, has made it an interesting alternative. This paper presents reliability and microstructural studies of eutectic 42%Sn-58%Bi (wt.%) lead-free solder alloy. The reliability was investigated using two different accelerated environmental tests. The first test series was subjected to isothermal aging at 100°C, the second series was subjected to salt spray test to analyze corrosion resistance, and the last test series was exposed to a combination of both tests. To study the effect of salt spray and isothermal aging on the mechanical reliability shear test and drop test were performed on the samples. A failure analysis was conducted and different types of failure modes were extracted. In addition, the effect of IMC types and growth on the mechanical strength of the solder joints was investigated.

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Low-cost manufacturing in the electronics industry is becoming more demanding, particularly in the production of consumer electronics. Such manufacturing processes require reliable and low-cost lead-free solders. Among the low-temperature lead-free solders, eutectic Sn-Bi solder attracts a great deal of interest as it offers good reliability compared with that of Sn-Pb solders. In this paper, the reliability of eutectic 42%Sn-58%Bi (wt.%) lead-free solder is studied using combinations of environmental tests such as thermal aging (TA) at 100°C, salt spray test (SST), and a sequential combination of TA and SST. Microstructural studies on the samples are performed at different time intervals. To study the effect of salt spray and TA on the mechanical reliability, drop testing is performed on the samples. Failure analysis is conducted after different tests. Marked corrosion is seen after the SST. This also has a considerable effect on the impact strength of the solder interconnections. TA increases the thickness of the intermetallic layers, which is found to affect the drop performance.Index Terms-Corrosion, drop performance, microstructure, Sn-58Bi lead-free solder.

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