Photo Stencil announces the results of Universal SMT Laboratories’ independent, extensive study, conducted in February 2006. The print-process study isolated the stencil alone to determine performance differences among a group of stencils manufactured by other stencil suppliers. Photo Stencil’s AMTX E-FAB stencil performed the best out of 12 stencils tested, provided by five different stencil manufacturers. The Xerox-authorized stencil manufacturer usse the AMTX Electroform stencil technology, licensed under U. S. Patents owned by Xerox and acquired by Photo Stencil in 1998.
The study included five electroform stencils and seven laser stencils, including Photo Stencil’s proprietary NicAlloy stencil. The report contains extensive data on the solder volume data for a range of SMT devices and aperture designs. Solder paste deposit heights, area and volume were measured for over 154,000 solder paste bricks. Solder paste volume and paste volume repeatability were measured for 16 SMT components in all 12 stencils. Both Pb-free and SnPb solder paste were used in the study. Stencils were ranked in paste volume delivery performance as well as paste volume repeatability. Photo Stencil’s E-FAB stencil provided the best paste transfer for both solder pastes among all stencils tested. NicAlloy was in second place for paste transfer.
The yield analysis program was used to determine the yield loss due to open defects of BGA and microBGA packages directly attributed to the stencil. The results show that compared to the best stencil, the increase in repair costs vary from an additional $658 for the second best to an additional $10,122 for the last place stencil. E-FAB provided the lowest rework cost for both solder pastes among all 12 stencils tested, with NicAlloy again coming in second.