Faculty Publications

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Subject: search.filters.subject.Lead free solder

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    Wetting behavior and evolution of microstructure of Sn-3.5Ag solder alloy on electroplated 304 stainless steel substrates
    (Springer India sanjiv.goswami@springer.co.in, 2012) Nayak, V.U.; Prabhu, K.N.; Stanford, N.; Satyanarayan, S.
    In the present study, wetting characteristics and evolution of microstructure of Sn-3.5Ag solder on Ag/Ni and Ni electroplated 304 stainless steel (304SS) substrates have been investigated. Solder alloy spread on Ag/Ni plated 304SS substrates exhibited better wetting as compared to Ni/304SS substrate. The formations of irregular shaped and coarser IMCs were found at the interface of solder/Ni/304SS substrate region whereas, solder/Ag/Ni/substrate interface showed continuous scallop and needle shaped IMCs. The precipitation of Ag3Sn, Ni-Sn, FeSn2 and lesser percentage of Fe-Cr-Sn IMCs were found at the interface of solder/Ag/Ni/substrate region whereas, solder/Ni/304 SS substrate exhibited predominantly FeSn2 and Fe-Cr-Sn IMCs. Presence of higher amount of Fe-Cr-Sn IMCs at the solder/Ni/304SS substrate interface inhibited the further wetting of solder alloy.
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    Effect of load and interface materials on thermal contact resistance between similar and dissimilar materials
    (Trans Tech Publications Ltd ttp@transtec.ch, 2014) Narayana, S.R.; Narayan, P.K.
    The thermal contact resistance (TCR) between similar and dissimilar materials (copper, aluminium, brass and type 304 stainless steel) was assessed. Copper foil, aluminium foil, lead and Sn-9Zn lead free solder were selected as thermal interface materials (TIMs). The interfacial contact pressure was varied by application of load on materials in contact. The interfacial heat flux was estimated by solving the inverse heat conduction problem (IHCP). At higher load, the temporal variation of thermal contact resistance showed early occurrence of peak and lower values of TCR. The use of thermal interface materials reduced the contact resistance between the hot source and cold sink materials. Among the interface materials used, Sn-9Zn lead free solder showed the lowest contact resistance. This was attributed to the solid to liquid phase transformation at higher temperatures and the conformance of the interface material to surfaces in contact. Factorial experiments were carried out to determine the significance of experimental variables on TCR. The analysis showed that the effect of applied load on TCR was significant compared to other parameters. © (2014) Trans Tech Publications, Switzerland.