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Item Wetting kinetics and joint strength of Sn-0.3Ag-0.7Cu lead-free solder alloy on copper substrate as a function of reflow time(Trans Tech Publications Ltd ttp@transtec.ch, 2015) Sona, M.; Prabhu, K.Solder plays a vital role in the interconnection of electronic devices in electronic assemblies. As an interconnection material, the solder joint executes electrical, mechanical and thermal functions. The use of lead bearing solders in electronic products is banned due to the toxicity and environmental risks coupled with lead. In the present study, wetting kinetics, interfacial reactions and the formation of intermetallic compounds (IMCs) during solidification of Sn-0.3Ag- 0.7Cu solder alloy on Cu substrate and the corresponding joint strength were studied as a function of reflow time. Experiments were carried out at various reflow times of 10, 100, 300 and 500s. The reflow temperature was maintained at 270°C. The solder alloy showed enhanced wettability on the substrate at longer reflow times. The thickness of IMC layer formed during a reflow time of 10s was 1.67μm and the thickness increased to 2.20μm, 2.85μm, 2.91μm during 100s, 300s and 500s of reflow time respectively. The joint shear test was performed to assess the integrity of Sn-0.3Ag- 0.7Cu solder solidified on Cu substrates using Nordson DAGE 4000 Plus bond tester. The joint strength increased with the increase in reflow time up to 300s and the maximum joint strength was observed for samples reflowed for 300s. Although the samples reflowed for 500s samples showed good wettability, they exhibited lowest joint strength. © (2015) Trans Tech Publications, Switzerland.Item Wettability and bond shear strength of Sn-9Zn lead-free solder alloy reflowed on copper substrate(Trans Tech Publications Ltd ttp@transtec.ch, 2015) Tikale, S.; Sona, M.; Prabhu, K.Lead-free solders are environment friendly and are in great demand for microelectronic applications. In the present study, Sn-9Zn lead free solder alloy was solidified on Cu substrate for different reflow times varying from 10 to 1000s. The influence of reflow time on wetting, bond shear strength and formation of intermetallic compounds (IMCs) was studied using dynamic contact angle analyzer, bond tester and scanning electron microscopy (SEM), respectively. The results indicate that, the wettability of the solder alloy increased with increase in reflow time. Microstructure study revealed the presence of Cu5Zn8 and CuZn5 IMCs at the interface. The thickness of an IMC increased with increase in the reflow time. A mean thickness of Cu5Zn8 IMC layer of about 11μm was obtained for a reflow time of 1000s. The thickness of CuZn5 layer increased up to a reflow time of 100s and decreased thereafter. The bond shear strength increased up to 100s and decreased with increase in reflow time. The decrease in shear strength at higher reflow time is mainly due to the formation of thick Cu5Zn8 IMC layer and diffusion of Sn from bulk solder towards the substrate. The thick IMC layer exhibited micro-cracks leading to the brittle failure of bond under the influence of shear stress. © (2015) Trans Tech Publications, Switzerland.Item Spreading Behaviour and Joint Reliability of Sn–0.3Ag–0.7Cu Lead-Free Solder Alloy on Nickel Coated Copper Substrate as a Function of Reflow Time(Springer India sanjiv.goswami@springer.co.in, 2015) Sona, M.; Prabhu, K.Solder joint directly interfaces electrically, mechanically and thermally with numerous electronic components in electronic assemblies. Sn–Ag–Cu lead-free solder alloys for electronic assembly are being driven by the environmental issues concerning the toxicity of lead. In the present study, spreading behaviour, evolution of intermetallic compounds during solidification of Sn–0.3Ag–0.7Cu solder alloy on Ni coated Cu substrate and the related joint strength were studied as a function of reflow time. Experiments were carried out for various reflow times of 10, 100, 300 and 500 s at a reflow temperature of 270 °C. The solder alloy exhibited improvement in wettability on the substrate at longer reflow times. An increase in the IMC (CuNi)6Sn5 thickness was observed for samples reflowed up to 300 s and the thickness decreased for samples reflowed for 500 s. IMC layer formed were about 0.3, 1.15, 2.03, 1.94 ?m during 10, 100, 300 and 500 s of reflow time respectively. The joint shear test was performed to assess the integrity of the Sn–0.3Ag–0.7Cu solder solidified on Cu substrates. The maximum joint strength was observed for samples reflowed for 100 s. © 2015, The Indian Institute of Metals - IIM.