Microstructure and reliability of Mo nanoparticle reinforced Sn–58Bi-based lead-free solder joints

Abstract

The effect of Mo nanoparticles on the microstructure, wettability and mechanical properties of Sn–58Bi– xMo ( x = 0–2.00) solder joints was investigated. The results showed that the optimal wettability of Sn–58Bi–0.25Mo solder was obtained and the microstructure was refined by adding small amounts of Mo. The intermetallic compounds (IMCs) thickness was increased from Sn–58Bi 2.17 µm to Sn–58Bi–2Mo 2.73 µm. The tensile strength of Sn–58Bi solder joint was improved by adding 0.25 wt-% Mo. The fracture mode of Sn–58Bi solder joint and Sn–58Bi–0.25Mo solder joint was brittle fracture and the mixed mode was ductile failure and brittle fracture, respectively. The microstructure of Sn–58Bi and Sn–58Bi–0.25Mo solder joints was coarsened, IMCs thickness was increased and the mechanical properties were deteriorated with increasing aging time.

Ultrasonic-Assisted Dispersion of ZnO Nanoparticles to Sn-Bi Solder: A Study on Microstructure, Spreading, and Mechanical Properties

“…Nucleation sites in the melt reduce the free energy barrier and promote the nucleation events during solidification (Ref 12 ). Additives acting as a potent nucleation site in Sn-Bi solder have been previously reported for the addition of graphite NPs (Ref 15 ), Mo NPs (Ref 4 ) and BaTiO 3 NPs (Ref 5 ). The effectiveness of an additive in enhancing the nucleation event depends on the contact angle established between the additive and the nucleating phase.…”

“…Addition of NPs in Sn-Bi solder alloy is an efficient way to improve the reliability of the solder joints by reducing the IMC thickness as well as refining the brittle Bi phase (Ref 3 ). NPs also enhance wettability (Ref 5 ), electro-migration performance (Ref 6 ), corrosion resistance (Ref 7 ) and reduce the coarsening of Bi phase upon aging (Ref 4 ). Wu et al (Ref 8 ) reported the addition of 1 wt.% ZnO NPs, substantially reduced the Cu-Ni-Sn thickness at the interface and increased the shear strength of Sn-57.6Bi-0.4Ag solder joints on Ni metallized Cu pads.…”

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

“…(b) A capillary phenomenon in which molten solder is sucked in the gap between two base metals, which is the recommendable gap in this case, is less than 0.3 mm. (c) The diffusion, which is the interatomic transfer between the solder and the base metal surface, must occur quickly [64]. In Sn-Bi-Sb solder, if Sb is added lower than 2 wt%, then the wettability of Sn-48%Bi will be improved [43].…”