PCB defect trends associated with the use of a no-clean flux and varying concentrations of oxygen in the wave soldering process atmosphere

Abstract

A large number of PCBs were wave soldered using a no-clean flux and gaseous atmospheres containing varying oxygen concentrations (ranging between 15 ppm and 21%) in nitrogen. This work was performed in order to develop a body of experimental data that might be useful in evaluating how gradually increasing concentrations of oxygen, in the wave soldering process atmosphere, would affect soldering defect trends. Except for the varying oxygen concentrations in the wave soldering atmospheres, all of the wave soldering equipment and other process conditions employed during this work were conventional. As a consequence of this experimental research study, it has been concluded that wave soldering in relatively pure nitrogen atmospheres is capable of making significant reductions in insufficiency or hole-type defects on bare copper-plated PCBs. However, there did not appear to be any significant differences in bridging behavior under any of the variable process atmosphere conditions employed during this experimental effort. No conclusions regarding other types of defects were possible as a direct result of this work.