Wetting behaviour of eutectic tin/lead solder and fluxes on copper surfaces

An apparatus for the measurement of reproducible dynamic contact-angle measurements is described and used to follow the interaction of a eutectic Sn/Pb solder on Cu surfaces at various temperatures. Because activated (glutamic acid hydrochloride type) and non-activated (abietic acid type) fluxes are commonly used for surface preparation of microelectronic components prior to soldering, the wetting behaviour of these fluxes on bare Cu and corrosion-inhibited surfaces with benzotriazole is also measured. The experimental results follow the Arrhenius equation; therefore, activation energies of wetting can be estimated. Surface reactions are proposed to account for the differences in wetting rates observed with the fluxes on the different Cu surfaces during the joining process. Graphs, Spectra. 10 ref.--AA