| 摘要 |
Conventional water-soluble soldering fluxes include those prepared by dissolving a large quantity of a carboxylic acid in pure water and adding thereto a tin (II) compound, an air shielding agent, etc. They have, however, such a strong acidity that the residue of soldering becomes corrosive. The water-soluble soldering flux of the invention is prepared by dissolving at least one organic acid selected from among malic, tartaric, malonic and ascorbic acids in glycerol to solve the aforementioned problem. Part of the flux is esterified in the course of soldering or when heated during polishing to liberate water, which causes dissociation of the organic acid which exhibits a strong acidity to thereby enable polishing of a metal surface. On the contrary, when the temperature of the flux is lowered, the acidity is reduced to thereby reduce the corrosiveness of the residue as much as possible. |
