The Kester 979 is a VOC-free, no-clean flux formulation for high quality, low-defect soldering of electronic circuit board assemblies. This flux's finely tuned activation system offers the best wetting available in VOC-free liquid flux technology and the shiniest solder joints. 979 also reduces micro solderballing on glossy laminates and between connector pins. - 979 will not attack properly cured solder masks or FR-4 Epoxy-Glass laminate. 979 leaves a minimal amount of residue after soldering. All remaining residues are non-corrosive, non-conductive and do not need to be removed.