Removing no clean flux residues from PCBs is another sub-set of electronics manufacturing and repair that requires special consideration. Most no clean fluxes are designed to remain on the board uncleaned, but if they need to be cleaned they are more difficult than old-style rosin-based fluxes. This is because no clean materials are prone to leaving white residues if not completely cleaned. They also contain activators which, if not fully encapsulated, can cause corrosion on the boards. These contaminates require a cleaner formulated with aggressive solvency, and possibly using inorganic fluids to fully remove any white residues.
For automated cleaning of large numbers of PCBs, vapor degreasers with spray under immersion may be necessary in order to reach the desired cleanliness specification. MicroCare offers several new formulations along with proven solvents that are strong candidates for replacing nPB in these applications.
Special feature: MicroCare Case Study #15 deals with the cleaning problems associated with mixed flux and solder paste residues, which can result in white residue.