Flux is an important component of both paste and wire solders. Flux allows component leads to flow and moisten properly onto PCB pads. Flux residues can occasionally induce contamination and even electrical migration between component leads (resulting in shorts) on the printed circuit board. High reliability applications including military, space as well as other essential ones - typically require the cleaning of so-called “No Clean” fluxes. PCB cleaning is highly needed for these types of circuit boards. The sales team at Restronics Southern California have years of experience in all types of flux cleaning... from high-volume batch cleaning machines to benchtop flux cleaning sprays and chemistry to dissolve flux residues. By evaluating the current process and providing relevant suggestions for development, we can decrease the physical labor necessary for hand spray cleaning and basically increase reliability and cleanliness by adopting a DI water-based batch cleaner with aqueous chemistry.
Because the majority of PCB manufacturers in the United States produce high-reliability boards, flux cleaning is vital. Cleaning printed circuit boards with solvents, while very effective, can be extremely detrimental to the planet and for humans. Organizations are shifting away from solvent-based cleaning and toward aqueous-based flux cleaning due to rising limits on the solvents used in vapor degreasers. Aqueous cleaners are usually zero-discharge, which implies that no wash solution or residue is discharged; it stays in the machine. Generally, wash chemistry is a combination of DI water and cleaning chemicals.
As part of PCB cleaning, the correct cleaning chemistry must match the nature of the soils (could be oils, flux residue, or other contaminants). Most people try to use a standard alcohol cleaner but it typically causes a white residue and does not remove flux. This is notably problematic when customers need the PCB to be conformally coated. Generally, conformal coatings won’t adhere effectively unless the PCB has been cleaned appropriately. Before applying conformal coatings to military and space applications, all flux residues should be removed and verified using an Ionic Contamination tester.