Life-Cycle Comparison of Energy Use during the Application of Lead-Free Solders
The energy consumed during the reflow assembly of printed wiring board assemblies is expected to be environmentally
significant within the solder product life-cycle. Wide differences in the melting temperatures of lead and lead-free solders
alternatives suggests that there may be large and important tradeoffs associated with the selection of solder and its ultimate
impact on the environment. Preliminary results of testing,conducted as part of an overall life-cycle assessment of lead and
lead free solders,are presented in this paper and then compared to previously conducted studies. Life-cycle impacts
associated the test data are also presented.
Testing results indicate that energy consumption can vary by as much as 40 percent across alternative solders,with the
National Electronics Manufacturing Initiative (NEMI) recommended Sn/Ag/Cu alloy consuming eight percent more energy
than eutectic Sn/Pb,and the Sn/Ag/Bi alloy consuming as much as 32 percent less energy. Although absolute energy
consumption values during this test were higher than other studies,relative energy differences between solder types strongly
agreed with those of previous studies. Finally,the environmental impacts associated with the energy consumed during reflow
assembly were demonstrated to be significant when compared energy use in upstream life-cycle processes.