Flux is a core element of both wire and paste solders. Flux promotes the correct flow and wetting of component leads onto PCB pads. Flux residues can occasionally lead to contamination and even electromigration between component leads (leading to shorts) on the circuit board. High reliability applications such as military, space and other essential applications - typically necessitate the cleaning of so-called “No Clean” fluxes. PCB cleaning is frequently needed for these kinds of circuit boards. Salespeople at Restronics Southeast have years of background in various forms of flux cleaning... from high-volume batch cleaning machines to benchtop flux cleaning sprays and chemistry to eliminate flux residues. By analyzing the process in use and supplying appropriate suggestions for development, we can minimize the human labor required for hand spray cleaning and generally increase cleanliness and dependability by employing 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 very effective, can be very detrimental to 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. Cleaners based on aqueous liquids are often zero-discharge, which means no residue or wash solution is discharged; it remains in the machine. 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 include flux residue, oils, or other contaminants). The majority of people try to use a simple alcohol cleaner but it typically causes a white layer and does not eliminate flux. This is particularly difficult when clients need the PCB to be conformally coated. Most conformal coatings won’t adhere adequately unless the PCB has been cleaned properly. All flux residues should be cleaned and verified using an Ionic Contamination tester before applying conformal coatings to military and space applications.