US Patent 11772208 Resin composition and soldering flux

Provided are a resin composition and a soldering flux. The resin composition includes at least one acid and rosin. The acid is selected from a dimer acid which is a reaction product of oleic acid and linoleic acid, a trimer acid which is a reaction product of oleic acid and linoleic acid, a hydrogenated dimer acid obtained by hydrogenating a dimer acid which is a reaction product of oleic acid and linoleic acid, and a hydrogenated trimer acid obtained by hydrogenating a trimer acid which is a reaction product of oleic acid and linoleic acid. A weight ratio of the at least one acid to the rosin is 0.15 or more and 1.00 or less based on the weight of the rosin. The soldering flux is obtained by diluting the resin composition with a solvent.