Effect of isothermal aging and salt spray tests on reliability and mechanical strength of eutectic Sn-Bi lead-free solder joints

Abstract

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.

Properties and Microstructures of Sn-Bi-X Lead-Free Solders

“…In recent twenty years, lead-free solders have made great development and several main kinds of Sn-based lead-free solders such as Sn-Ag [6,7], Sn-Zn [8,9], Sn-Bi [10,11], Sn-Cu [12,13], and Sn-Ag-Cu [14,15] have been fiercely studied by researchers. Among these most promising lead-free solder alloys, however, the Sn-Bi solder alloys have better properties such as lower melting temperature, good tensile strength, good reliability, and well creep resistance [16][17][18]. The eutectic Sn-58Bi solder has a low melting point of 139 ∘ C [19,20] and it is lower than 183 ∘ C of the eutectic Sn-Pb solder which consists of 63 wt.% Sn and 37 wt.% Pb [21,22].…”

Surface Morphology Study of Nanostructured Lead-Free Solder Alloy Sn-Ag-Cu Developed by Electrodeposition: Effect of Current Density Investigation

“…Regardless of the great finding from the lead-free solder related research, it was found that the main disadvantages of the lead-free solder is high melting temperature [3], [4], [5], insufficient fatigue resistance and low reliability characteristic inhibit wide practical application in industry [6]. The increase of melting temperature in lead-free solder has already been a disadvantages to the manufactures since it leading to significant capital expenditure and resulting in the increase of product cost [7].…”