Heat and mass transfer effects of laser soldering on growth behavior of interfacial intermetallic compounds in Sn/Cu and Sn-3.5Ag0.5/Cu joints

A data-driven framework to predict the morphology of interfacial Cu6Sn5 IMC in SAC/Cu system during laser soldering

“…Pbfree solder sheet with dimensions of (l × b × h = 4 mm×2 mm×0.2 mm) was placed over polycrystalline Cu substrate (5 mm×5 mm×0.1 mm). In our previous work [17] , only pure Sn and Sn-3.5Ag-0.5Cu solders were considered for study, whereas this works aiming to infer the effect of solder composition of a generic Sn-xAg-yCu solder, additionally considers Sn-0.7Cu, Sn-3.5Ag, Sn-3.0Ag-0.5Cu and Sn-3.5Ag-0.7Cu solders. Thus, the types of solders considered in this study are outlined in Table 1, with their respective Ag and Cu weight fraction based (mi) composition.…”

“…The partial differential equation (PDE) for phase change based heat transfer during laser soldering in a Sn-xAg-yCu solder [17] :…”

“…The effective heat capacity (Ceff) of the Sn-xAg-yCu alloy is a function of enthalpy (H) and is described as following [17] :…”

“…The transient and spatially non-uniform temperature profile during laser soldering lead to interfacial microstructural evolution totally different from that of conventional isothermal reflow soldering [16] . The formation of interfacial IMCs of two different morphologies of IMC-prismatic and scalloped, at the interface of Sn/Cu and Sn-3.5Ag-0.5Cu/Cu systems, due to the alteration in the value of laser power and scan speed has been reported in [17] . However, the work uses only two solder compositions and so the solder alloy composition dependence of IMC could not be outlined quantitatively from the study.…”

“…In SAC solder alloys consisting of Ag, another intermetallic compound, namely Ag3Sn is formed along with Cu6Sn5 compound in the aftermath of laser soldering [17] . Ag3Sn intermetallic nanoparticles are found to be adsorbed on the top of micrometer sized Cu6Sn5 IMC.…”