Pb-free Design and Process Optimization for PIH

The assembly process must be optimized by understanding the relationship between PIH solder joint quality and several design and process variables including stencil design (thickness, aperture shape, and dimension); printing parameters (pressure, speed, squeegee angle, stroke, and separation); printing method (squeegee, closed-head); PCB (surface finish, thickness, annular ring design, hole dimension); component (pin penetration, pin dimension, and shape); and solder paste (Sn/Pb and lead-free). A Design of Experiment (DOE) was conducted on the screen printing process using four different stencils. Various PCB variables, stencil apertures, solder paste printing methods and parameters, component types, and insertion methods have been evaluated for the PIH technology for Sn/Pb and lead-free solders.