| abstract |
By addition of a polyamide resin, which is compatible with rosin-based resins as the main components of liquid flux and solder paste flux, which is resistant to temperature variation and provides a damp proofing effect, and particularly a polyamide resin which is obtained by polycondensation reaction of a dicarboxylic acid of 2 to 21 carbon atoms and a diamine and has a softening point of 80 DEG to 150 DEG C., or a polyamide resin which is obtained by polycondensation reaction of a dimer acid and a diamine and has a softening point of 80 DEG to 150 DEG C., highly reliable low-viscosity liquid fluxes and solder paste fluxes, with which solderability is not impaired, where the flux residues on printed circuit boards after soldering undergoes no cracking or deterioration even under temperature variation, and which prevent poor insulation and migration even under high humidity environment, are provided. |