Screen process

Platemaking is a prelude to printing, and conventional printing is not accomplished by first transferring the graphic on the manuscript to the surface of the plate. Now, with the rapid development of high technology, most of the introduction of computer technology, so that the combination of graphics, color separation, direct output; not only single-plane, dual-plane or multilayer circuit board circuit graphics transfer, plate making Can be completed at one time. Its production is very convenient and concise. It can be done in the street shops casually.

Now we introduce the whole process of a plate making:

Manuscripts - Photographs - Typesetting - Copying - Revision - Printing: The printing process is the most important in this set of processes. The quality of its production directly influences the printing effect, and it can be seen from the manufacturing process of printing. Divided into stretch net, coating, drying, exposure, development and other workflows:

The stretch net stretches the screen to the frame. Frame; It can be made of metal, wood or other materials. The four sides of the frame are required to be balanced. The edges of the frame are connected together with adhesive; when selecting the screen, various requirements of the product are printed. To choose and use. At present, nylon meshes and polyester meshes are used at the most. Nylon meshes have poor heat resistance and easily undergo thermoplastic changes after being heated, thereby causing uneven tension and affecting screen printing quality. Polyester's heat resistance is good, and it won't cause large changes in the surface due to temperature changes. So in the general case, most people make use of polyester mesh. Stretching the net is also a part that cannot be overlooked. The latitude and longitude must be straight, otherwise it will cause partial moire. The stretch net should also pay attention to the tension of the wire mesh. If the tension is too large, the wire mesh can easily break without losing elasticity; Small, the screen is prone to slack and cannot achieve optimal printing results, so the best method is to use a tensiometer to measure.

Coating is to apply photoresist on the screen, then we must let the water discharge, so that the degree of drying is improved, if the degree of dryness is not enough, will make the photosensitive adhesive layer with water vapor, then in the exposure of water vapor on the light refraction Affects the speed of cross-linking and cross-linking of the photoresist, resulting in a number of problems such as pinholes, glue, or reduction in the number of prints during development of the retina, so the photosensitive layer must be dry during exposure. The generation of pinholes is the most common. It can cause problems such as sticky printing, local ink layer deposition, and thinning. It is mainly due to the method of drying the photosensitive adhesive and the method of drying the adhesive after it is dried. When the printing plate is not completely dried, the coating speed is not equal; therefore, drying after screen coating is performed according to the positive angle method, and the screen plate is placed horizontally for drying, and the general temperature is below 40 degrees; and The sensitization during printing does not dry completely. The screen plate is placed in a drying oven, and moisture on the direct screen plate is evaporated from the surface; the presence of water will reduce the activity of the background light and hinder the photosensitive sensitivity of the light. Sometimes it is impossible to do anything on both sides of the screen. In fact, the interior is not completely dry and must be further dried to ensure that the water is fully evaporated. Also pay attention to coating speed and coating pressure. The speed can not be too slow, because it is easy to cause uneven coating, the pressure can not be too large, because the central part of the screen will be disengaged from the edge of the glue head during the coating process, resulting in the coating thickness of the central part is too thick, and The adhesive layer on the side is too thin. As a result, there was insufficient exposure in the central area.

The exposure time should be based on the intensity of the light source and the distance between the light source and the screen. When the light is strong, the time is short when the distance is near the exposure, and long when the distance is near. In the general case, the appropriate light source and distance should be selected because the long exposure time is always better than the underexposure, but the time is too short and the development is lost. At the outlets, there will be a phenomenon of blocking, causing problems such as blockage.

In the development time can not be too long, the plate shakes back and forth in the water, until a certain degree, rinse with wash water once again, when drying the screen can not be placed together with the developed screen, otherwise there will be pinholes The phenomenon. The surface of the squeegee is solid and back-to-light, so the exposure cannot be completely cured. After developing, it becomes wet and sensible, and this layer must be washed away with the sensitized adhesive. Otherwise, it will be closed.

After development, the screen plate is basically completed after drying, repairing, and other processes. The above is only a general idea, and there are many technologies that are not listed one by one.