Solder circuit card pre-clean process to prevent the formation of white residues

摘要

In the brazing process using an aqueous base flux, the electrical components are soldered onto the circuit card, and then the brazed electrical component containing circuit card is exposed to the dilute aqueous basic solution prior to the final hot water rinse. Dilute basic solutions prevent the formation of white residues associated with the use of aqueous based fluxes. For example, cleaning with an aqueous ammonia solution of 20-250 ppm ammonium hydroxide or an aqueous solution of 0.1-3 wt% sodium bicarbonate using an aqueous citric acid-containing flux is prevented from forming a white residue.