Soldering flux and method of its use in fabricating and assembling circuit boards.

摘要

A water-soluble soldering flux which does not adversely impact the surface insulation resistance of a circuit board is comprised of a water-soluble vehicle, an activator and a hydrophobic surfactant preferentially adsorbed at the board surface. At soldering temperatures, the activator reacts to clean metallized areas on a circuit board and promote solder wetting. The hydrophobic surfactant, which is preferentially adsorbed at the board surface, acts to block the diffusion of hydrophilic vehicle molecules into the board which would otherwise degrade the board's surface insulation resistance.