A non-Newtonian computational fluid dynamics study of the stencil printing process文档.pdf

437 A non-Newtonian computational ¯ uid dynamics study of the stencil printing process G P Glinski, C Bailey* and K A Pericleous Centre for Numerical Modelling and Process Analysis, School of Computing and Mathematical Sciences, The University of Greenwich, London, UK Abstract: This paper describes the application of computational ¯ uid dynamics (CFD) to simulate the macroscopic bulk motion of solder paste ahead of a moving squeegee blade in the stencil printing process during the manufacture of electronic components. The successful outcome of the stencil printing process is dependent on the interaction of numerous process parameters. A better under- standing of these parameters is required to determine their relation to print quality and improve guidelines for process optimization. Various modelling techniques have arisen to analyse the ¯ ow behaviour of solder paste, including macroscopic studies of the whole mass of paste as well as microstructural analyses of the motion of individual solder particles suspended in the carrier ¯ uid. This work builds on the knowledge gained to date from earlier analytical models and CFD investi- gations by considering the important non-Newtonian rheological properties of solder pastes which have been neglected in previous macroscopic studies. Pressure and velocity distributions are obtained from both Newtonian and non-Newtonian CFD simulations and evaluated against each other as well as existing established analytical models. Signi® cant diVerences between the results are observed, which demon