| 摘要 |
PROBLEM TO BE SOLVED: To provide a flux composition and a solder paste composition which keep an adhesive force of a flux residue at a fixed value or more even when placed under an environment large in cold-heat shock, and can prevent advancement of cracks of a solder joint and reduction in a solder shear strength of the solder joint caused by the advancement of the cracks.SOLUTION: The flux composition contains a synthetic resin having an acid value, a thixotropic agent, an active agent, and a solvent and contains, as the synthetic resin having an acid value, an acryl resin obtained by polymerizing monomers containing a methacrylic acid and a monomer having two saturated 2-20C alkyl groups composed of a linear carbon chain. An adhesive force of a flux solidified product formed by heating the flux composition is 0.2 N/mmor more after 2,000 cycles of the cold-heat shock tests have been conducted on the flux solidified product with one cycle of -40°C/30 minutes to 125°C/30 minutes.SELECTED DRAWING: Figure 1 |
