Nickel is proving to be a valuable element aiding the move to cost-effective Pb-free assembly at high production volumes. When screen printing with Pb-free (SAC) solder pastes, stencils made from pure nickel or a nickel alloy help to achieve paste transfer efficiency comparable to the levels achieved using SnPb pastes with stainless steel laser-cut stencils. Combined with the efficiencies of the frame-mounted interchangeable foil stencil system, nickel is the optimal stencil medium for maximum Pb-free process repeatability and productivity.

Laboratory tests have highlighted a reduction in paste transfer efficiency because of the higher coefficient of friction between SAC ...