SatyanarayanKumarswamy, M.C.Prabhu, K.N.2020-03-312020-03-312019Transactions of the Indian Institute of Metals, 2019, Vol.72, 6, pp.1545-1549https://idr.nitk.ac.in/handle/123456789/13374In the current study, the influence of thermal ageing on evolution of microstructures in the interfacial region between solders (Sn 37Pb, Sn 3.5Ag 0.5Cu) and copper substrates was investigated. Pb-containing and Pb-free solders were reflowed on Cu substrates at 230 C for 15 min and were isothermally aged at 100 C for 24 h. As-reflowed Sn Pb solder/Cu substrate interfacial region exhibited continuous and layered type of IMC at the interface, and this IMC morphology changed to scallop type with isothermal ageing. SAC solder/Cu as-reflowed samples showed continuous and needle-shaped Cu6Sn5 and Ag3Sn IMCs at the interface. However, in an isothermally aged condition, plate-shaped Cu6Sn5 and flower-shaped Ag3Sn IMCs were found inside the solder matrix. Scanning electron microscopic (SEM) study showed that the thickness of Cu6Sn5 IMC was higher in reflowed Sn Pb/Cu region than in SAC/Cu region. 2019, The Indian Institute of Metals - IIM.Article