| abstract |
To provide a water-soluble flux excellent in solder wettability and spreadability. A water-soluble flux containing the following components (A) and (B). (A) component: selected from (a1) a structural unit derived from a carboxylic anhydride having a polymerizable unsaturated double bond, and (a2) a structural unit obtained by hydrolyzing the structural unit (a1) And (a3) a polymer having a structural unit derived from an alkyl vinyl ether. Component (B): As an activator, at least one selected from amine salts of hydrochloric acid, amine salts of hydrobromic acid, carboxylic acids, ammonium salts of carboxylic acids, amine salts of carboxylic acids and polyhydric phenols . [Selection figure] None |