Flux is an integral element of both wire and paste solders. Flux allows component leads to flow and moisten properly onto PCB pads. Flux residues can occasionally lead to contamination and even electromigration between component contacts (leading to shorts) on the PCB. High reliability uses including military, space as well as other essential implementations - usually necessitate the cleaning of so-called “No Clean” fluxes. PCB cleaning is frequently needed for these types of circuit boards. Salespeople at Restronics Arizona have years of expertise in all types of flux cleaning... from benchtop flux cleaning sprays to higher volume batch cleaning machines and chemistry to eliminate flux residues. By evaluating the current process and supplying appropriate suggestions as to how to improve it, we can minimize the manual labor necessary for hand spray cleaning and generally improve cleanliness and dependability 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 PCBs with solvents, although quite effective, can be very dangerous for the environment and for users. 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 generally zero-discharge, which indicates that no wash solution or residue goes to the drain; it stays in the equipment. In general, wash chemistry is a mixture of DI water and cleaning chemistry.
The appropriate cleaning chemistry must complement the composition of the soils as part of PCB cleanup (could include flux residue, oils, or other contaminants). Most people try to utilize a standard alcohol cleaner but it typically causes a white residue and doesn’t remove flux. This is particularly difficult when clients need the PCB to be conformally coated. Usually, conformal coatings will not adhere effectively unless the PCB has been cleaned effectively. Prior to applying conformal coatings to military and space applications, all flux residues must be cleaned and tested with an Ionic Contamination tester.