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Item Reactive wetting of Sn-2.5Ag-0.5Cu solder on copper and silver coated copper substrates(Springer Science and Business Media, LLC, 2013) Prabhu, K.In the present work, wetting characteristics and morphology of intermetallic compounds (IMCs) formed between Sn-2.5Ag-0.5Cu lead-free solder on copper (Cu) and silver (Ag) coated copper substrates were compared. It was found that, Ag coated Cu substrate improved the wettability of solder alloy. The average values of contact angles of solder alloy solidified on Ag coated Cu substrate were reduced to about 50 % as compared to contact angles obtained on Cu substrates. Flow restrictivity for spreading of solder on Ag coated Cu was found to be lower as compared to Cu substrate. The spreading of solder alloy on Ag coated Cu exhibited halo zone. Coarse needle shaped Cu6Sn 5 IMCs were observed at the solder/Cu substrate interface whereas at the solder/Ag coated Cu interface Cu6Sn5 IMCs showed scallop morphology. The formation of Cu3Sn IMC was observed for the spreading of solder alloy on both substrates. The solder/Ag coated Cu substrate interface exhibited more particulates of Ag3Sn precipitates as compared to solder/Cu substrate interface. The improved wettability of solder alloy on Ag coated Cu substrate is due to the formation of scallop IMCs at the interface. © Springer Science+Business Media New York 2012.Item Spreading behavior and evolution of IMCs during reactive wetting of SAC solders on smooth and rough copper substrates(2013) Satyanarayan, S.; Prabhu, K.The effect of surface roughness of copper substrate on the reactive wetting of Sn-Ag-Cu solder alloys and morphology of intermetallic compounds (IMCs) was investigated. The spreading behavior of solder alloys on smooth and rough Cu substrates was categorized into capillary, diffusion/reaction, and contact angle stabilization zones. The increase in substrate surface roughness improved the wetting of solder alloys, being attributed to the presence of thick Cu 3Sn IMC at the interface. The morphology of IMCs transformed from long needle shaped to short protruded type with an increase in the substrate surface roughness for the Sn-0.3Ag-0.7Cu and Sn-3Ag-0.5Cu solder alloys. However, for the Sn-2.5Ag-0.5Cu solder alloy the needle-shaped IMCs transformed to the completely scallop type with increase in the substrate surface roughness. The effect of Ag content on wetting behavior was not significant. © 2013 TMS.