Removal of organic films from solid surfaces using aqueous solutions of nonionic surfactants. 2. Theory

The removal of organic films of solder flux components (abietic acid in isopropyl alcohol) from disks of epoxy-glass laminate by aqueous solutions of nonionic surfactant (C{sub 12}-E{sub 5}) proceeds through three stages. The controlling mechanisms in each stage were deduced from experimental observations. In this paper, theoretical models are developed to analyze the cleaning rates in the three different stages. The duration of the first stage is calculated assuming that convective and diffusive transport of surfactant monomer into the organic film controls the stage. The second stage is analyzed considering that shear forces remove aggregates from a continuous film of liquefied residue, while the third stage cleaning rate model is based on the shear-induced removal of isolated aggregates adsorbed directly to the solid substrate. Parameters in the models are evaluated using experimental cleaning rate data.