Abstract :
In this paper, the effect of the squeegee attack angle on pressure distribution along the stencil surface during the stroke has been investigated. At first, a Finite Element Method (FEM) model has been developed to determine the true attack angle of the squeegee for given printing forces. The model has also been validated with experiments. As a next step, a Finite Volume Model (FVM) has been developed to calculate the pressure distribution along the surface of the stencil, applying non- Newtonian fluid properties for the solder paste. With the aid of this model, the pressure distribution has been determined for unloaded squeegees (attack angle is 60°) as well as for loaded squeegees, where a printing force of 0.32 N/mm resulted in an attack angle of 55°. The results showed that there was a noticeable difference between the pressure distributions, ca. 16 % in average for a change 5° in the angle. Finally, pressure distributions were determined at attack angles of 45, 50, 55, 60°.
