Stencil printing process performance on various aperture size and optimization for lead-free solder paste

Abstract

The present study examines the effect of squeegee load, squeegee speed, and separation speed on the printing performance of lead-free solder paste, and solder printing was carried out to evaluate the effect of the filled volume of the solder paste during stencil printing. Application of pressure on the squeegee affects the filled volume of the solder paste in the stencil aperture, and the incorrect pressure setting could cause incomplete filling. Herein, an experiment was conducted on a printing machine employing surface mount technology. The solder paste used in the study was Sn/Ag/Cu (SAC305), and four components, namely, 0603, small outline transistor (SOT), 1210, and tantalum-D, were tested. The filled volume and height of the solder paste under different squeegee loads, squeegee speeds, and separation speeds were determined, and the solder volume was found to vary with the squeegee load and component type. Response surface method (RSM) optimization is conducted to obtain optimum filled volume and solder paste height and area during the printing process. The method showed squeegee load, squeegee speed, and separation speed have considerable effects on filled volume, solder paste height, and solder paste area.