printed circuit technology demands a high level of dependability and performance from electronic equipment. field failures do occur, however, often caused by soldering flux residues and other surface contamination remaining on the circuit boards after manufacture. the removal of soldering flux residues and other contaminants has become necessary because of the growing realization that these contaminants can be a significant cause of signal alteration in electronic assemblies. contamination, especially when combined with humidity, can also cause such conditions as galvanic corrosion of conductive traces, blistering on conformal coated assemblies, and metal migration on the board surface. these problems may show up in the form of quality control rejections, field failures that may show up in the form of quality control rejections, field failures that may be costly to repair, and the need for extensive and costly failure investigation. the author concentrates on cleaning boards with an aqueous batch washing approach