ALPHA RS7MI has an activated rosin flux core. The halide activator system provides extremely good tarnish removing properties. RS7MI has good soldering performance even on very difficult soldering surfaces. ALPHA RS7MI leaves post-soldering residues that are hard and which can be safely left without need to remove them (depending on classification of end use product). If the removal of residues is required then, semi aqueous or aqueous systems can be used effectively.