Modeling of the paste withdrawal sub-process in the stencil printing of solder pastes for the reflow soldering of surface mount assemblies

摘要

Accurate and repeatable deposition of solder paste by stencil printing onto a substrate remains a critical step in the reflow soldering of surface mount components. To achieve consistency in the deposition process, an undersatanding of the mechanisms of paste transfer during the printing process is very essential. This paper concentrates on the aperture emptying sub-process, the modelling of the paste withdrawal from the aperture and teh mechanisms for the formation of the printing defect known as skipping.