Evaluation on Mechanical Properties of Sn-Bi-Ag Solder and Reliability of the Solder Joint

Abstract

This paper presents low-temperature Pb-free soldering technology using Sn-57Bi-1Ag (mass%). Here, the effects of hightemperature annealing on the mechanical properties of the solder such as tensile strength and elongation are investigated. The experimental results show that during annealing, the sizes of both of Sn and Bi phases coarsen, however the mechanical properties do not deteriorate. The deformation behavior of Sn-57Bi-1Ag is found to be dependent on sliding at grain boundaries between Sn and Bi phases, and this behavior remains consistent even after coarsening. The creep strength of solder joint at high temperature is also studied, and it is found that Sn-57Bi-1Ag exhibits superior creep strength at temperature below approximately 100°C compared to the Sn-37Pb (mass%) solder.The thermal cycling test of Sn-57Bi-1Ag solder joint is also conducted under the condition between 0°C and 90°C. The result shows that the length of crack is shorter than Sn-37Pb in the same conditions, which means Sn-57Bi-1Ag is an effective material for low temperature soldering.

Low Melting Temperature Sn-Bi Solder: Effect of Alloying and Nanoparticle Addition on the Microstructural, Thermal, Interfacial Bonding, and Mechanical Characteristics

“…This can be attributed to the agglomeration of nanoparticles reported in various studies [93][94][95][96][97][98][99]. Agglomeration of a nanoparticles in the solder causes serious impediment tot eh reliability [100][101][102][103][104][105][106][107][108][109][110][111][112]. A. El-Daly et al [111] reported that the effect of the rotating magnetic field (RMF), which generates Lorentz forced flow during solidification, on the microstructure of Sn-20%Bi and Sn-20%Bi-0.4 Cu alloys.…”

“…Resultantly, the Bi segregation at the SnBiAg/Cu joint interface was suppressed, and the aging embrittlement at long-term aged SnBi/Cu will not occur. Shin et al [106] studied the interfacial IMC between Sn-58%Bi solder paste and ENIG (5 µm of Ni-P, 0.15 µm of Au layer) finished Cu-pad PCB. Figure 6 shows the cross-sectional SEM micrographs of the solder joints between Sn-58%Bi solder and Electroless nickel immersion gold (ENIG) finished substrate after aging at 125 for 0, 30, and 100 h. The thickness of interfacial IMC is seen to increase with the aging time.…”

Cu and Ag additions affecting the solidification microstructure and tensile properties of Sn-Bi lead-free solder alloys

“…Nevertheless, the related elongation values (ductility) are lower for the Sn-33wt%Bi-2wt%Ag alloy. According to Suganuma et al [35] and Shimokawa et al [36] the addition of Ag in quantities higher than 0.8wt.% may favor the formation of primary Ag 3 Sn and as a consequence decrease the ductility. Another investigation [12] reported that by adding 0.4 wt.% Ag in Sn-Bi, fine Ag 3 Sn particles can be present in dispersed form inside the solder matrix, whereas large-sized primary Ag 3 Sn IMCs were formed with 1.0 wt.% Ag addition.…”