Screen printing is the most popular and mature technology for printed electronics, since it has been used in electronics industry to print metallic interconnects on printed circuit boards for a long time. It is faster and more versatile than other versions of printing. The fabrication process is simple, affordable, quick, and adaptable. The results of screen printing can be reproduced by repeating several steps, which allows quickly organize the work line. The screen printer consists of a screen, squeegee, press and substrate. Ink is poured on the screen (stencil) and moved around the screen by squeegee, which pushes ink through the stencil onto substrate beneath. Tablet screens can be replaced with a rotating screen for continuous processing, in which the screen cloth is twisted into a cylinder, and the squeegee and ink are placed inside the tube. This allows to achieve high-speed printing, but screens for rotational installation are expensive and difficult to clean.
The ability to print relatively thick layers enables printing of low-resistance structures, as well as with conductive polymers, by compensating the high-volume resistivity with a thicker layer. Material, strength and number of meshes in screen also play an important role when printing with high resolution. Screen printing is used for the development of OLED-objects by changing the structure of the process and solution, i.e. viscosity and the number of screen meshes.
Advantages of screen printing
- - possibility of printing on any surfaces;
- - simple technology;
- - low cost;
- - high speed of printing;
- - printing of thick layer (from 8-10 microns to 1000 and more, for offset the ink layer is 1-2 microns).
Disadvantages of screen printing
- - relatively low resolution of a picture.