Flux activity evaluation using the wetting balance

The selection of soldering flux plays a critical role in determining the manufacturing yield and product reliability of printed circuit board assemblies. Fluxes are used to remove oxides and other contaminants on the component leads and the pads on the printed circuit board. They also assist in the transfer of heat. The selection of flux should depend on properties such as its ability to remove the (oxides) tarnish film, activation temperature, corrosiveness, and the resistivity of post process residues. The activity level of a flux influences its ability to clean the oxides on the specimen's surface and to promote wetting. It (the flux activity level) may be altered by changing the contents of the activators that make-up the flux chemistry. This research provides an approach to evaluate the influence of the flux activity in promoting wetting through the use of wetting balance analysis. Standardized specimens were used along with a set of specified test variables. The experimental procedure was determined based on the information obtained through initial experiments. The results obtained can serve as a bench mark for evaluating candidate fluxes for future use in the manufacturing process.