Faculty Publications

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    Bond shear strength of Al2O3 nanoparticles reinforced 2220-capacitor/SAC305 solder interconnects reflowed on bare and Ni-coated copper substrate
    (Springer, 2021) Tikale, S.; Prabhu, K.N.
    The influence of Al2O3 nanoparticles addition in trace amounts and electroless Ni–P substrate coating on the microstructure development and bond shear strength of Sn-3.0Ag–0.5Cu (SAC305) solder joint were investigated. The performance and reliability of the 2220-capacitor joints with Al2O3 nanoparticle reinforced nanocomposites reflowed on Cu and Ni–P coated substrate were analyzed under varying high-temperature environments. The addition of nanoparticles enhanced the wettability and microhardness of the solder and considerably refined the joint microstructure. The dispersion and adsorption of Al2O3 nanoparticles resulted in the suppression of intermetallic (IMC) growth at the interface and refinement of the ?-Sn grains as well as IMC precipitates into the matrix. The Ni–P coating on the substrate significantly retarded the IMC growth kinetics resulting in the formation of a thin and uniform IMC layer at the joint interface. The thermal stability and performance of the joint under high-temperature environments were enhanced due to the Ni–P coating on the substrate. Compared to the unreinforced SAC305 solder joint with bare Cu substrate, joints with SAC305 + 0.05Al2O3 composite showed about 17% higher shear strength with bare Cu substrate and about 27% higher strength with Ni–P coated substrate. The Weibull distribution analysis indicates a significant improvement in joint reliability of the 2220-capacitor/SAC305 solder assembly using SAC305 + 0.05Al2O3 nanocomposite and Ni-coated substrate. The ANOVA study suggests that the solder joint performance majorly depends on the operating environment, solder composition, and the substrate finish. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.
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    Effect of Ni nanoparticles reinforcement on wettability, microstructure and mechanical properties of SAC387 lead-free solder alloy
    (Elsevier Ltd, 2025) Muhammed, H.J.; Prabhu, K.N.
    The study investigates the influence of nickel (Ni) nanoparticles on the wettability, microstructure, and mechanical properties of Sn-3.8Ag-0.7Cu (SAC387) lead-free solder alloy. Nanocomposite solders containing 0.3 wt% and 0.5 wt% Ni were prepared and reflowed at temperatures of 230 °C, 250 °C, and 270 °C to evaluate their performance on copper substrates with a surface roughness (Ra) of 0.01 ± 0.002 ?m. Wettability improved with increasing reflow temperature; however, the addition of Ni nanoparticles had minimal direct impact on spreading behavior. Microstructural analysis revealed enhanced formation of interfacial intermetallic compounds (IMCs), particularly (Cu,Ni)6Sn5 which contributed to improved joint stability. The optimal mechanical performance was observed at 250 °C with 0.3 wt% Ni addition, yielding a 51.14 % increase in shear strength compared to the unreinforced solder. Microhardness also improved significantly by 43.7 % at the IMC layer and 18.3 % in the solder bulk. Weibull analysis further confirmed higher joint performance with Ni nanoparticle incorporation. These findings highlight the potential of addition of Ni nanoparticles in improving the performance of SAC387 solder joints in electronic packaging. © 2025 Elsevier Ltd