Flux is an important element of both wire and paste solders. Flux allows component leads to flow and moisten properly onto PCB pads. Flux residues can possibly induce contamination and even electrical migration between component leads (causing shorts) on the printed circuit board. High reliability applications including military, space and other essential implementations - usually necessitate the cleaning of so-called “No Clean” fluxes. PCB cleaning is often required for these kinds of PCBs. The sales team at Restronics Metro have years of expertise in various forms of flux cleaning... from high-volume batch cleaning machines to benchtop flux cleaning sprays and chemistry to eliminate flux residues. By reviewing the process in use and providing appropriate recommendations for development, we can decrease the human labor needed for hand spray cleaning and ultimately increase cleanliness and reliability by adopting a DI water-based batch cleaner with aqueous chemistry.

Because the majority of US manufacturers produce high-reliability PCBs, flux cleaning is critical. Cleaning printed circuit boards with solvents, though very effective, can be extremely detrimental to the environment and for operators. As a result of rising limitations on the solvents used in vapor degreasers, firms are shifting away from solvent-based cleaning to aqueous-based flux cleaning. Cleaners based on aqueous liquids are generally zero-discharge, which indicates that no residue or wash solution is discharged; it remains in the equipment. Wash chemistry is often a blend of DI water and cleaning chemicals.

As part of PCB cleaning, the correct cleaning chemistry must match the nature of the soils (could involve oils, flux residue, or other contaminants). Most people try to utilize a basic alcohol cleaner but it typically causes a white residue and does not remove flux. This is especially challenging when clients need coat the PCB in a specific pattern. Most conformal coatings won’t adhere properly unless the PCB has been cleaned properly. Prior to applying conformal coatings to military and space applications, all flux residues must be cleaned and tested with an Ionic Contamination tester.