| abstract |
Disclosed is a surface treatment agent that has heat resistance and can form a good film even after being exposed to high humidity, and a printed circuit board having rust prevention properties. SOLUTION: 5-butyl-2,4-diphenyl-1H-imidazole, 5-butyl-4-naphthalen-1-yl-2-phenyl-1H-imidazole, 5-hexyl-2-naphthalen-1-yl-4 -A surface treating agent comprising an aqueous solution containing one or more specific imidazole compounds selected from the group consisting of phenyl-1H-imidazole, etc. and a water-soluble organic acid having 1 to 4 carbon atoms, and a water-soluble composition comprising the same. Related to preflux. Moreover, a printed circuit board provided with a rust preventive film having good moisture resistance can be obtained by applying this surface treating agent. [Selection figure] None |