Faculty Publications
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Item Effect of Multiple Reflow Cycles and Al2O3 Nanoparticles Reinforcement on Performance of SAC305 Lead-Free Solder Alloy(Springer New York LLC barbara.b.bertram@gsk.com, 2018) Tikale, S.; Prabhu, K.N.The effect of Al2O3 nanoparticles reinforcement on melting behavior, microstructure evolution at the interface and joint shear strength of 96.5Sn3Ag0.5Cu (SAC305) lead-free solder alloy subjected to multiple reflow cycles was investigated. The reinforced SAC305 solder alloy compositions were prepared by adding Al2O3 nanoparticles in different weight fractions (0.05, 0.1, 0.3 and 0.5 wt.%) through mechanical dispersion. Cu/solder/Cu micro-lap-shear solder joint specimens were used to assess the shear strength of the solder joint. Differential scanning calorimetry was used to investigate the melting behavior of SAC305 solder nanocomposites. The solder joint interfacial microstructure was studied using scanning electron microscopy. The results showed that the increase in melting temperature (TL) and melting temperature range of the SAC305 solder alloy by addition of Al2O3 nanoparticles were not significant. In comparison with unreinforced SAC305 solder alloy, the reinforcement of 0.05-0.5 wt.% of Al2O3 nanoparticles improved the solder wettability. The addition of nanoparticles in minor quantity effectively suppressed the Cu6Sn5 IMC growth, improved the solder joint shear strength and ductility under multiple reflow cycles. However, the improvement in solder properties was less pronounced on increasing the nanoparticle content above 0.1 wt.% of the solder alloy. © 2018, ASM International.Item The effect of multi-walled carbon nanotubes reinforcement and multiple reflow cycles on shear strength of SAC305 lead-free solder alloy(ASTM International, 2019) Tikale, S.; Prabhu, N.In this study, the effect of multi-walled carbon nanotubes (MWCNT) reinforcement on joint shear strength and microstructural development of tin-3.0silver-0.5copper (SAC305)/ copper solder joint subjected to multiple reflow cycles was investigated. The MWCNT-reinforced SAC305 solder systems (SAC305-x MWCNT; x = 0.01, 0.05, 0.1, and 0.5 wt.%) were developed by a mechanical dispersion method. The microstructural, mechanical, and melting properties of SAC305 composite solders were evaluated as a function of different wt.% of MWCNT addition. The melting behavior of composite solders was analyzed using differential scanning calorimetry. The morphology and intermetallic compound growth at the solder joint interface were studied using scanning electron microscopy. The copper/solder/ copper micro-lap-shear solder joint specimens reflowed for multiple reflow cycles were systematically characterized to evaluate the joint shear strength. The results showed that the reinforcement in the range of 0.01-0.05 wt.% of MWCNT resulted in the improvement of joint shear strength and better wettability compared to plain SAC305 solder alloy. Amongst all compositions analyzed, SAC305-0.05MWCNT nanocomposite suppressed the intermetallic compound layer growth effectively leading to improvement in the joint shear strength under multiple reflow cycles. © 2019 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959Item Development of low-silver content SAC0307 solder alloy with Al2O3 nanoparticles(Elsevier Ltd, 2020) Tikale, S.; Prabhu, K.N.The present study is focused on the development of low Ag content 99Sn-0.3Ag-0.7Cu (SAC0307) solder alloy with Al2O3 nanoparticles reinforcement. The effects of multiple reflow cycles and the addition of Al2O3 nanoparticles in 0.01, 0.05, 0.1, 0.3 and 0.5 percentages by weight on microstructure development and mechanical strength of the solcder joint were first investigated. The addition of ceramic nanoparticles in 0.01-0.5 wt% range resulted in 15-40% increase in the wetting area and about 10-55% increase in the microhardness of the solder. The shear strength of nanoparticles reinforced SAC0307 solder joint increased by 11-53% under multiple reflow conditions. Nano-composite solder joints containing 0.01 and 0.05 wt% Al2O3 nanoparticles showed superior shear strength and improved ductility for two reflow cycles. Hence, these nano-composites were selected and tested for their performance and joint reliability. The surface mount 2220 capacitor joint assemblies with the selected nano-composites reflowed on bare copper and Ni–P coated Cu substrates were investigated. The reliability of the solder joint was assessed by determining the joint shear strength under varying temperature environments. The nano-composite with 0.05 wt% nanoparticles addition resulted in maximum joint reliability compared to monolithic solder. The Ni–P coating on the Cu substrate significantly hindered the IMC growth at the joint interface under different thermal conditions. The joint strength improved by about 26% for samples reflowed on Ni–P surface finish compared to that on bare Cu metallization. The Weibull analysis of the joint shear strength under all thermal conditions suggest that the addition of Al2O3 nanoparticles in very small amounts to SAC0307 solder and the presence of Ni–P surface finish on Cu substrate significantly enhances the performance and reliability of solder joints. In terms of both quality and reliability, the newly developed low-silver content SAC0307+0.05Al2O3 nano-composite is an effective alternate lead-free solder that can be used in microelectronics industry in place of high-silver content Sn–Ag–Cu solders. © 2020 Elsevier B.V.Item Performance and reliability of Al2O3 nanoparticles doped multicomponent Sn-3.0Ag-0.5Cu-Ni-Ge solder alloy(Elsevier Ltd, 2020) Tikale, S.; Prabhu, K.N.The effect of Al2O3 nanoparticles addition on melting, microhardness, microstructural, and mechanical properties of multicomponent Sn-3Ag-0.5Cu-0.06Ni-0.01Ge (SACNiGe) solder alloy was investigated. The shear strength of the capacitor assemblies under varying high-temperature environments for different nanocomposites was assessed and the reliability of the joint was determined using Weibull analysis. The SACNiGe solder doped with 0.01 and 0.05 wt% Al2O3 nanoparticles to prepare nanocomposites and tested on the solder joints for their performance and reliability under different thermal conditions. Plain copper and Ni[sbnd]P layer coated substrates were used to investigate the effect of different surface finish on the joint reliability. The addition of ceramic nanoparticles in small amounts did not affect the melting parameters of the solder. In comparison with the bare solder alloy, nanocomposites yielded about 20% increase in tin-climb height and 14% higher microhardness. The dispersion of ceramic nanoparticles in the matrix and presence of Ni and Ge elements in the solder resulted in substantial microstructure refinement and about 24% supression in intermetallic compounds (IMCs) growth at the joint interface. In comparison with the bare Cu substrate, the Ni[sbnd]P coating on the substrate provided a strong diffusion barrier, promoted thin and complex (Cu, Ni)6Sn5 IMC layer formation at the interface, and significantly retarded the IMC growth kinetics under elevated temperature conditions. Under varying thermal conditions, nanoparticles doped solder compositions showed about 20% increase in the joint shear strength value. The reliability of joints improved appreciably with the addition of 0.05 wt% Al2O3 nanoparticles in the solder. Samples with SACNiGe+0.05Al2O3 nanocomposite reflowed on Ni[sbnd]P coating showed about 32% higher reliability than that on the uncoated-copper substrate. The SACNiGe solder joint performance and reliability could be significantly improved by minor weight percent addition of Al2O3 nanoparticles in the presence of Ni[sbnd]P coating on the substrate. © 2020 Elsevier LtdItem 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.