Residues RAT was used to investigate a standard procedure for cleaning flux residues. Hand soldering was performed in three places on two similar PCBA´s, one of which a consequent cleaning procedure was done. Then both PCBA’s were tested with Residues RAT for presence of unreaced flux.
3 Hand soldered areas cleaned (75% isopropanol / 25% Di water) / 3 Hand soldered areas without cleaning
The hand-soldered areas become clearly red when tested with Residues RAT. The board that was cleaned with a mixture of isopropanol and DI water and then swapped with a tissue shows less coloration; however, Residues RAT also reveals that active flux residues are not removed from the surface, but smeared to a larger region.