Effects of Ce and Zn additions on the microstructure and mechanical properties of Sn–3Ag–0.5Cu solder joints

The study of mechanical properties of Sn–Ag–Cu lead-free solders with different Ag contents and Ni doping under different strain rates and temperatures

“…Hence, the different effect trends of Ag content on thermal fatigue life and drop performance were obtained. In order to improve drop performance without reducing the thermal fatigue life of the electronic assembly with Sn-Ag-Cu lead-free solders, some metal additives, such as Ni, Zn, Fe, Co and rare-earth (RE) elements, have been introduced into Sn-Ag-Cu solders to refine the microstructures and reduce the intermetallic compound growth [4][5][6][7][8][9][10][13][14][15][16][17][18][19][20][21][22]. Among the additives, Ni is one dominant and widely used doping material in Sn-Ag-Cu solders due to its excellent performance in improving solder microstructure, reducing IMC growth and increasing the drop lifetime of electronic assembly [4][5][6][7][8][9][10].…”

“…doi:10.1016/j.jallcom.2010.07.160 an excessive Cu 6 Sn 5 growth during the reflow stage and aging condition. Recently, some researchers found that the addition of RE elements in Sn-Ag-Cu solders can refine the microstructure and improve the tensile strength and wettability [14][15][16][17][18][19][20][21][22]. Wang et al [17] reported that the solderability and mechanical properties of Sn-3.8Ag-0.7Cu solder can be improved by adding light RE Ce in a range of 0.03-0.05 wt.% because the Ce makes the Cu 6 Sn 5 and Ag 3 Sn precipitates become smaller and uniformly distributed.…”

“…The rapid growth of tin whiskers has been observed on the surface of Sn-3.0Ag-0.5Cu-0.5Ce solder joints of ball grid array (BGA) packages due to the coarse CeSn 3 intermetallic cluster effect [21]. The rapid tin whisker growth can be prevented by adding 0.2 wt.% Zn into Sn-3.0Ag-0.5Cu-0.5Ce solder and the tensile strength of Sn-3.0Ag-0.5Cu-0.5Ce-0.2Zn solder improved significantly compared with that of Sn-3.0Ag-0.5Cu-0.5Ce solder [22]. However, the long-term reliability, such as thermal cycling and the electromigration effect due to high current density, are not clear for lead-free solders with RE addition compared with Ni doped solders, which needs to be investigated.…”

“…However, the long-term reliability, such as thermal cycling and the electromigration effect due to high current density, are not clear for lead-free solders with RE addition compared with Ni doped solders, which needs to be investigated. So far, most of the studies focused on the effects of Ag content and metal additions on the solder microstructures [7][8][9][10][13][14][15][16][17][18][19][20][21][22][23][24][25]. Even though some researchers [2,26,27] investigated the effect of Ag content on fracture behavior and fatigue properties of Sn-Ag-Cu solder, there is a lack of a systematic investigation in the effect of Ag content and metal additions on the mechanical properties of Sn-Ag-Cu solders, e.g., elastic modulus and yield stress.…”

A Study of Temperature, Microstructure and Hardness Properties of Sn-3.8Ag-0.7Cu (SAC) Solder Alloy

“…2 and 3 which identified a microstructure with compact configuration and wider eutectic phase containing intermetallic compounds will increase the hardness of the solder alloy. As noted by [45], solders with wider eutectic area has higher surface area per unit volume that contributes to increase in strength. A theory called dislocation strengthening mechanism justifies this phenomenon and based on the theory, a wider eutectic area have grain boundaries with smaller surface area making it harder to dislocate the grain boundaries resulting in increased hardness of the solder alloy.…”