Flux is a crucial part of both wire and paste solders. Flux facilitates the proper flow and wetting of component leads onto PCB pads. Flux particles can sometimes induce contamination and even electromigration between component leads (leading to shorts) on the circuit board. High reliability operations including space, military and some other mission-critical ones - typically demand the cleaning of so-called “No Clean” fluxes. PCB cleaning is highly necessary for these kinds of PCBs. The sales staff at Restronics Mid Atlantic have years of expertise in flux cleaning of all types... from benchtop flux cleaning sprays to higher volume batch cleaning machines and chemistry to dissolve flux residues. By analyzing the process in use and providing proper suggestions as to how to improve it, we can minimize the manual labor necessary for hand spray cleaning and ultimately improve 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, though extremely effective, can be extremely dangerous for the environment and for operators. 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 typically zero-discharge, which indicates that no wash solution or residue discarded; it remains in the device. 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). Several people try to apply a standard alcohol cleaner but it usually causes a white sediment and does not eliminate flux. This is especially problematic when clients need to conformally coat the PCB. Generally, conformal coatings won’t adhere effectively unless the printed circuit board 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.