The process cleaning rate theorem holds that the static rate (chemical forces) plus the dynamic cleaning rate (mechanical forces) equals the process cleaning rate. New lead-free flux residues result from more demanding soldering drivers created by high soldering temperature, surface tension effects, and miniaturization. Lead-Free flux compositions require thermal stability, resistance against burn-off, oxidation resistance, oxygen barrier capability, low surface tension, high fluxing capacity, slow wetting, low moisture pickup, high hot viscosity, and halogen free. The static cleaning rate for lead-free flux residues is dramatically different from eutectic tin-lead flux residues. To clean lead-free soils, longer wash exposure time, high cleaning agent concentrations, and high levels of mechanical energy are needed. The purpose of this research paper is to measure the cleaning variability induced by lead-free flux residues and to compare the cleanability of lead-free flux residues to determine the viability of new cleaning agent designs.
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