Finite volume modelling of stencil printing process

Nowadays, stencil printing process has become one of the most crucial steps in the continuously developing reflow soldering technology. In this research, the process of stencil printing was modelled with Finite Volume Method. The geometrical model consists of the squeegee with attack angle of 60°, the stencil and the solder paste as the domain of interest. During the modelling, the flow field inside the paste and the pressure distribution along the stencil surface were calculated. The effect of various types of meshes (quadrilateral, triangular, unstructured and polar) on the calculation speed and accuracy was investigated. The calculation error was determined by contrasting the results to an analytical model which is available for liquids with Newtonian properties. Although solder pastes are non-Newtonian liquids, comparing numerical models to analytical models provides the most reliable validation. Finally, the FVM model with non-Newtonian solder paste properties were compared to the results of Newtonian modelling.