PRINTING ANGLE EXAMPLES

In most cases a 60º angle is used for printing solder paste and other high viscosity materials through an open aperture stencil. With this type of angle, the bead of solder paste should roll across the stencil surface like a steam roller, with the natural rolling motion causing the solder paste to fill the stencil apertures and deposit onto the pads of the printed circuit board (pcb). JNJ's Electrolized coated metal squeegee blades enhance the rolling process, allowing solder paste to roll up and then off the surface of the blade and back down to the stencil for deposition to the pcb. The specially prepared blade edge with ball radius will shear the paste off at the stencil surface for uniform pad print deposition with minimal surface abrasion to the stencil.

When screen printing through a cross sectional screen mesh with an emulsion, a 45º angle is used along with polyurethane squeegee blades. The sharper angle drags the print media across the screen surface, while simultaneously pumping the media (inks or epoxy's) down through the emulsion to be deposited onto the substrate. The thickness of the print deposit is typically determined by the diameter of the screen wire and the thickness of the emulsion.  Variations to the thickness can be accomplished by adjusting the "snap off" height, squeegee pressure and speed, and also by the squeegee blade durometer. Softer (lower durometer) squeegee materials will penetrate the screen mesh more than harder materials, altering the thickness of the deposit.

 

 See the Polyurethane Squeegees" blade page or the various individual printer pages from the "Squeegee" sub menus for all of the available metal and polyurethane squeegees.