Retardation Effect of Tin Multilayer on Sn-3.0Ag-0.5Cu (SAC305)-Based Solder Joint Interface

A Comparative Study on the Influence of SAC305 Lead‐Free Solder Sandwiched by Sn on the Micromechanical and Electrical Properties of the Joints

“…Authors have also previously identified the presence of (ε‐Cu 3 Sn + η‐Cu 6 Sn 5 ) intermetallics at the interface of such, Cu–SAC305 solder joints produced at 230 °C reflow temperature. [ 27 ] After electron dispersive spectroscopy followed by transmission electron microscopy‐selected area diffraction pattern analysis Kar et al [ 30 ] confirms the presence of ε and η at the interface. It was also confirmed that the formation of thicker intermetallics contributes to the embrittlement of the solder joint interface.…”

“…It is reported in previous studies [ 46,47 ] that the thicker IMC layers formed gradually at the interface, due to the diffusion of Cu from the substrate into solder alloy. Char et al [ 27 ] have reported that different kinetics for the IMC layer growth has been observed in the presence and in absence of Sn thin film. Relatively faster IMC layer growth has been reported for the solder joints produced in absence of Sn interlayers.…”

“…In our previous study, it was reported that the presence of Sn interlayers restricts the diffusion of Cu through the IMC layer hence restrict the growth of IMC layer thickness. [ 27 ]…”

“…Metal Stores, Kolkata) as substrate following transient liquid phase like soldering technique. [ 27 ] To remove the surface oxides and other contaminants, Cu substrates were polished and dipped into an etchant solution (prepared using methanol and FeCl 3 of 10% conc.). A solder joint assembly, i.e., Cu–SAC305–Cu using only SAC305 solder paste (with an approx.…”

“…In our previous study, it was reported that the presence of Sn interlayers restricts the diffusion of Cu through the IMC layer hence restrict the growth of IMC layer thickness. [27] For any diffusion-controlled bonding processes (brazing/ soldering) Ray et al [45] have reported that different intermetallic phases formed during the processing of the joint play a key role in determining the joint quality. As the coefficient of thermal expansion (CTE) of the substrates (Cu), filler alloys (SAC), and other IMC phases are different, the formation of various IMC, its volume fraction, and the relative spatial distributions of phases are the most important factors to lessen the overall stresses evolves due to CTE mismatch at the joint interface during the processing of the joint.…”