Solder Paste for No Clean Reflow

Abstract

This article describes a low‐cost approach to the search for alternatives to CFC cleaners. In this approach the cleaning and soldering cycles are combined under nitrogen. The effects of inerted reflow are reviewed and quantified. A no‐clean solder paste to take advantage of the inert atmosphere is described and compared with conventional formulations. Processing conditions are outlined. Finally, process and capital costs of the new product are compared. The article concludes that the new formulation performs as well as conventional pastes, but leaves fewer residues than a separate cleaning process. Process and capital costs are less than half those of liquid cleaning.