New normal‐propyl bromide based cleaning technology for the electronics industry

Precision cleaning with solvent systems based on n‐propyl bromide (nPB) has become an important component of the circuit board fabrication process. The nPB‐based cleaners have proved themselves valuable alternatives to the once popular chlorocarbons and hydrochlorocarbons. These latter solvents have been largely banned or restricted because of toxicological and/or environmental considerations. n‐propyl bromide has nearly identical physical and cleaning properties to 1,1,1‐trichloroethane (1,1,1‐T or TCA), but it has a low Ozone Depletion Potential (ODP) and a low Global Warming Potential (GWP). A growing body of evidence shows that nPB‐based solvents are safe, effective and cost‐efficient alternatives for precision cleaning applications. New formulations have now been developed specifically for the electronics industry. The first challenge is the efficient removal of ionic residues left by certain types of solder flux. The second challenge is the prevention of tarnish on silver leads used on some circuit boards. Case histories and a discussion of relevant toxicological, environmental and regulatory considerations will be included.