| abstract |
A non-washing soldering flux which is capable of minimizing corrosion and insulation defects due to precipitation of metal salts and cracking of the base resin is disclosed. The flux includes an activator including a dibasic acid with a molecular weight of 250 or less, and a monobasic acid with a molecular weight of from 150 to 300 and/or a dibasic acid with a molecular weight of from 300 to 600. The dibasic acid of molecular weight 250 or less in the flux exhibits sufficient activity, thus ensuring satisfactory solderability. The monobasic acid of molecular weight from 150 to 300 and the dibasic acid of molecular weight from 300 to 600 which are combined therewith promote the activity while also uniformly dispersing the metal salt of the low molecular weight dibasic acid in the flux residue, allowing it to be enveloped by the hydrophobic base resin. For greater cracking resistance, the flux includes at least an acrylic resin of molecular weight 10,000 or less and an activator. |