Flux is a crucial part of both wire and paste solders. Flux promotes the correct flow and wetting of component leads onto PCB pads. Flux residues can occasionally induce contamination or perhaps even electrical migration between component contacts (leading to shorts) on the PCB. High reliability systems including space, military and other mission-critical ones - usually demand the cleaning of notable no-clean fluxes. PCB cleaning is often necessary for these sorts of circuit boards. The sales staff at Restronics Northland have years of background in flux cleaning of all types... from high-volume batch cleaning machines to benchtop flux cleaning sprays and chemistry to eliminate flux residues. By reviewing the process in use and supplying relevant suggestions as to how to improve it, we can reduce the physical labor required for hand spray cleaning and basically improve dependability and cleanliness by adopting a DI water based batch cleaner with aqueous chemistry.
The majority of US manufacturers make high reliability PCBs, so flux cleaning is essential. Cleaning circuit boards with solvents, while extremely effective, can be extremely hazardous for the surroundings and for users. Due to increasing restrictions on solvents used in Vapor Degreasers, companies are switching from solvent based cleaning to aqueous based flux cleaning. Cleaners based on aqueous liquids are generally zero-discharge, which implies that no residue or wash solution is discharged; it stays in the machine. In general, wash chemistry is a mixture of DI water and cleaning chemistry.
As part of PCB cleaning, the correct cleaning chemistry must match the nature of the soils (could include oils, flux residue, or other contaminants). Several people try to utilize a simple alcohol cleaner but it generally produces a white layer and doesn’t remove flux. This is especially problematic when customers need coat the PCB in a specific pattern. Usually, conformal coatings will not adhere properly 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.