High-quality lead-free solder wire for manual and automatic soldering in electrical engineering, electromechanics, and electronics. The flux is characterized by high temperature resistance and does not spatter during melting. Optimal wetting and performance values that exceed standards make this lead-free solder wire a top product among tube solders. The new flux formulation, Ultra-Clear, is based on synthetic resins (free from rosin) and has been perfectly tailored to the new requirements of lead-free soldering technology: high wetting speed and spread on all surfaces commonly used in electronics, no (painful) flux splatters on the assembly, equipment parts, or the hands of users, crystal-clear flux residues to enhance the optical impression, minimal outgassing and neutral odor reduce workplace exposure, easily removable residues on soldering tips, which can be cleaned with conventional means, passed the 100 MΩ test - also suitable for use in assembly production, significantly extends the lifespan of soldering iron tips.