Research Of The Mathematic Model Of Fine-line Screen Printing Process

Compared with other printing methods, screen printing has many own advantages, is used widely in electron industry,ceramic decals industry, packaging and decoration industry, advertisement industry and so on. However the development of fine-line screen printing has encountered obstacles because screen printing depends on empirical evaluation is lack of theoretical guidance.Based on the screen printing power-law fluid model satisfied momentum and continuity equations, this article supposes that the distance between screen and squeegee is near 0 and analyses the law of paste transfer and puts forward screen printing pressure model that paste pressure changes with the distance from contact point. Based on the screen printing Newtonian fluid model satisfied Navier-stokes equations, this article uses the boundary conditions that the paste velocity on screen surface is equal to the squeegee speed, simplifies screen printing model. This article analyses and puts forward models of four processes of paste transfer on the screen, inject into the mesh, release from the screen and deposited on the substrate.Based on these researches, this article analyses the effect of snap-off distance to location accuracy of screen printing and finds the range of best snap-off distance firstly; this article also analyses the effect of squeegee speed and angel to the thickness accuracy of paste deposited and puts forward the tentative idea that while adjusting printing machinery, we can change the angle and speed of squeegee to control the paste pressure exactly. These two points are main results and innovation of this article. Then we test and verify power-law fluid model and Newtonian fluid model through experiment. These two models are in good agreement with the experimental results. And we also find that the best proportion between mesh diameter and the largest particle diameter is between 5 and 6.The research of the mathematical model of screen printing can provide theoretical basis for actual production. And it is important to improve the accuracy and quality of screen printed matter.