Screen Printing and High-tech Membrane Switch Manufacturing Technology

First, the application of membrane switch in high-tech fields

Membrane switch is one of the few independent products that can be used for screen printing in the high-tech field.

Membrane switches have a decorative function and a marking function that are provided by a conventional panel. Besides a switch element and a switch function of the switch element, the thin film switch also has a switch connection and a lead line (that is, a switch circuit) function that connects the switch element and the host circuit. With the readings showing the transparent window and the indicator light transparent window function, the membrane switch is neither a single new type of panel nor a single switch element, but an electronic whole product set with functions and decorations is a novel electronic device.

Since the membrane switch has the characteristics of simple structure, beautiful appearance, excellent environmental resistance, long service life, lightness, thinness, shortness, and smallness, it conforms to the direction of high integration and high-intelligent development of modern electronic devices. The favor of technology products.

Second, the special characteristics of membrane switch screen printing

Screen printing has been focusing on decorative effects since its invention. 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 ink used in the membrane switch mainly guides the electric silver paste, conductive carbon paste, high-performance conductive silver, carbon ink and insulating ink.

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. In order 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, in order to prevent PET from experiencing a high temperature of 130 degrees Celsius. After processing, the shrinkage of the film occurs. Before the printing, the PET must be heat-fixed or directly purchased PET that has been overheated.

(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, PET surface can easily absorb dust in the air. The processing of PET surface before printing is done to eliminate static electricity, which can greatly improve the printing quality and ensure the electrical conductivity of the silver paste circuit.

3, strict quality inspection system

In addition to the color rendering of the ink switch and the color reproducibility required by the customer, the quality of the membrane switch must focus on the intrinsic qualities of the membrane switch, such as the key force, life, peel strength, and high and low temperatures. Constant wet heat and loop resistance, insulation resistance, pressure resistance and other indicators.

Third, the high-tech screen printing

In addition to the above content, screen printing incorporates high-tech membrane switch manufacturing technology. There are also many new contents that are different from traditional screen printing, such as computer-aided design (CAD) and manual wiring design of membrane switch circuits; isolation Layer window and air duct design; Insulation ink and its ultraviolet (UV) curing application; Non-metallic conductor carbon paste application; High-tech computer numerical control (CNC) electronic autofocus precision punch on the membrane switch working environment And storage environment. Obviously we should be based on the working environment and storage environment of the membrane switch. Obviously, we should consider the membrane switch's structural design and material selection according to the working environment and storage environment of the membrane switch. Today's screen printing has developed into a new multi-disciplinary modern screen printing technology integrating optical, mechanical, electrical, chemical, photochemical, microelectronics, and computer technologies.

Fourth, summary

Membrane switch technology in the production of the panel layer both the reproducibility of the color in the traditional screen printing, the color rendering of ink, which is the traditional screen printing decoration function, in the production of its circuit layer must also pay attention to the circuit The high-tech content is obvious because of its conductive properties, prevention of oxidation of silver paste circuits, migration of silver ions, multilayer interchange circuits, and the reliability of membrane switch products.

Source: International Packaging Network