Reliability Testing Results of Surface Mounted Lead Free Soldering Materials and Processes

摘要

The world-wide movement to phase out lead from electronic products presents many challenges for companies throughout the electronics supply chain. The University of Massachusetts at Lowell has brought together many Massachusetts/New England firms to collaborate on the manufacture and testing of lead-free printed wiring boards (PWBs). The results of the first set of experiments, published in 2001, showed that zero-defect soldering is achievable with lead-free materials. Following thermal cycling, the PWBs were visually inspected and the leads were pull-tested for reliability analysis. They compared favorably to a baseline of lead soldered PWBs A follow-on design of experiments was created in 2002 and a second set of test PWBs was made and tested in 2003. Three lead-free solder pastes based on Sn/Ag/Cu alloys were reflowed using either air or nitrogen with five PWB surface finishes, four component types with two types of component finish. Visual inspection and pull-testing were performed and published as completed in APEX, SMTI and IEEE conferences. This paper summarizes the testing results and introduces further research plans in volume manufacturing of lead free PWBs for the phase III testing sponsored by the EPA.