A STUDY OF THE OFF-CONTACT SCREEN PRINTING PROCESS .2. ANALYSIS OF THE MODEL OF THE PRINTING PROCESS

The analysis presented in this paper is concerned with the derivation of equations which allow calculation of the thickness of dry paste deposited on a substrate in the off-contact screen printing process. The rheological properties of the paste are approximated by those of a “power-law” fluid. Deformed squeegee shape in the paste deposition region is considered to be that of a wedge. he equations show that the height of the deposited paste depends on the magnitude of the equivalent paste height under the squeegee and on the paste flow speed under the squeegee. The equivalent paste height under the squeegee depends, for a given screen, on the deformability of the squeegee and on the emulsion height. The paste flow speed under the squeegee depends, for a given paste and screen, on the magnitude of the pressure build-up ahead of the squeegee. The pressure build-up in turn is a function of the squeegee deformation characteristics and of squeegee translational speed. © 1990 IEEE