Soft film switch screen printing special
The special nature of the soft membrane switch screen printing, screen printing from its inception until now has focused directly on the decorative effect. In addition to the common commercial features, another common feature is the requirement for good reproducibility of colors and patterns and the color rendering capability of the ink during screen printing in order to achieve the decorative effect.
1. Functional ink
Color design, color reproducibility, and color rendering of ink are important factors in evaluating the quality of the membrane switch. However, the more important factor in evaluating the performance of the membrane switch is the conduction function of the membrane switch and the reliability of the conductive circuit. Even if the membrane switch panel layer has a good color design, color reproducibility, and color rendering of the ink, if the switch's conduction function and the reliability of the conductive circuit are lost, everything is awkward.
The on-off function of the membrane switch and the reliability of the conductive circuit depend on the use of the functional ink and other treatment measures. The functional inks used in membrane switches are mainly used to guide electrical pastes, conductive carbon pastes, high-performance conductive silver, carbon inks, and insulating inks.
The on-off function of the membrane switch and the reliability of the electrical circuit there are related not only to the quality of the functional ink, but also to the correctness and rationality of the circuit design in the production process, screen making and printing methods, and the like. For the control of the thickness of screen-sensitive material (photosensitive film or photographic film), an excessively thick photosensitive layer will result in wastage of expensive functional ink and increase the manufacturing cost; while too thin a photosensitive layer will seriously affect the film. The conductive properties of the switch.
2. Substrate processing
The functional ink (silver paste) in the membrane switch is printed on the polyester film (PET) by screen printing. Because of the relationship between the characteristics of the silver paste and the PET properties, a certain number of treatments must be performed on the PET before printing. , to ensure the smooth operation of screen printing and silver paste PET on the firm adhesion.
(1) Heat setting treatment
The silver paste circuit printed on PET must be heated and dried in a tunnel drying tunnel at 130 degrees for about 30 minutes or in an oven to cure. Only after this process, the silver paste circuit has conductive properties, so as to prevent the PET from experiencing a high temperature of 130 degrees Celsius. After processing, the shrinkage of the film occurs, and the PET must be heat-set before printing or the PET that has been subjected to the overheating treatment must be directly purchased.
(2) Surface polarity treatment
By corona bombardment and the like, the polar group of the hydrophilic functional ink is obtained on the PET surface, so that the silver paste has firm adhesion on the PET.
(3) Electrostatic protection
Due to the influence of static electricity, the PET surface can easily adsorb dust in the air. Before the printing, the PET surface is treated to eliminate static electricity, which can greatly improve the printing quality and ensure the conductivity of the silver paste circuit.