COLORADO SPRINGS, CO -- A study comparing print performance of electroform and laser-cut stencils in

terms of percent paste transfer and dispersion in paste transfer volume is available from Photo Stencil.

The study looked at a variety of electroform and laser-cut stencils with and without post processing treatments. Side wall quality was also investigated. The purpose was to determine which provides the best paste release results for small apertures while providing enough solder paste volume for normal-sized surface mount (SMT) components.

The paper is titled "Print Performance Studies Comparing Electroform and Laser-cut Stencils" and is coauthored by Rachel Miller-Short and William E. Coleman Ph.D., of Photo Stencil, in collaboration with Joseph Perault of Parmi.

"There has been recent activity and interest in laser-cut electroform blank foils as an alternative to normal electroform stencils," said Miller-Short. "As components get smaller, it is difficult to print solder paste to satisfy the requirements of both very small components, such as 0.4 and 0.3mm pitch CSPs, as well as normal SMT components.

"The large components require more solder paste volume for sufficient solder fillets after reflow. However, if the stencil normally used to print solder paste for SMT components is used for the small components, the apertures are so small that poor paste release may be encountered. The area ratio plays a large part in this dilemma. Our study details the performance of 12 stencils in five different categories.