Rework of components increases the risk of unreacted flux residues to be left on the surface of PCBAs. The main issue here is whether this rework procedure results in a reliable product. Therefore it is important 1) to know the amount and spreading of unreacted flux residues around the reworked components and 2) optimize the cleaning procedure to minimize the amounts of active residues on the PCBA.
A reworked IC / Standard re-flow solder with no coloration of Residues RAT
Residue RAT detects active flux residues and show how a reworked IC appears clearly red at all four sides. This can cause accelerated corrosion and leakage current issues during use of the electronic product