Determination of Spread Activation Energy and Assessment of Wetting Behavior of Solders on Metallic Substrates

Abstract

The effects of substrate material, substrate surface roughness, and operating temperature on the wetting behavior of Sn–37Pb, Sn–3.5Ag, and Sn–9Zn eutectic solders on metallic substrates were investigated. Solder spreading kinetics was successfully represented by the exponential power law (EPL): ϕ=exp(−Kτn). The EPL parameter K has the significance of accelerating the kinetics of relaxation while the parameter n represents the resistance to spreading process (spread resistance parameter). EPL parameters exhibited a decreasing trend with an increase in surface roughness. Estimated activation energies for solder spreading were found to be in between those reported for inert and highly reactive spreading systems.