Kester 951 Soldering Flux Pen, Low-Solids, No-Clean, 10mLKester 951 Flux Pen is a zero halogen, non rosin Flux Pen that is specifically designed for rework of conventional and surface mount circuit board assemblies. The extremely low solids content (2. 0%) and nature of the activator system results in practically no residue left on the assembly after soldering. There are no residues to interfere with electrical testing. 951 exhibits improved soldering performance to minimize solder bridges (shorts) during