Abstract. SMT printing will require reexamination and process adjustment when lead-free soldering is implemented. If a high quality solder paste is used and standard rules for SMT printing are followed, consistent stencil life, aperture release, print definition, high-speed print capabilities and print repeatability may be expected.
Introduction. As compared to tin-lead solder pastes, lead-free pastes should exhibit similar features on the stencil and many equipment set points should transition well. However, implementation of lead-free solder paste does necessitate some adjustment, as well as providing an opportunity to review and fine-tune several key printing parameters.
Many manufacturers currently use reduced aperture-to-pad ratios to prevent bridging and solder beading. Due to...
