The silk screen printing technology, which has been used since ancient times for printing text and patterns, is also being actively utilized in the electronic field. Through the active use of silk screen printing technology, it is possible to mass-produce precise electronic devices quickly.
This article explains the basic information about silk screen printing, examples of its active use in the electronic field, and the expected methods of utilization in the future.
{ 0. Concept of Silk Printing }
Silk screen printing is a type of stencil printing, where ink is transferred onto a substrate through a silk screen mask (plate) that has openings in the shape of text or patterns.
The printing principle is simple; it can print even on uneven surfaces, and if it is paste-like, any material can be used as ink, allowing for printing on various objects. Since ancient times, it has been used to print text and patterns on the surfaces of items such as clothing, utensils, and electrical products.
I. Silk Screen Printing Used in the Manufacturing of Electronic Components
The active development of silk screen printing technology in the electronics field has been vigorously pursued in recent years. Among them, the technology known as "Printed Electronics," which uses printing technology capable of high-speed mass production of fixed patterns to create wiring suitable for electronic devices, has a wide range of applications including silk screen printing techniques.
In printed electronics, it is very important to choose ① conductive materials and ② be able to do precise printing on that material. These two elements are highly emphasized in the direction of silk screen printing technology development.
II. Types of Ink
Silk screen printing is a printing method with a very high degree of freedom in material selection. Silver paste is generally used for wiring printing, but there are many other options. For instance, carbon paste is also a commonly used material. Since silver is prone to sulfidation, carbon paste replaces silver in applications requiring durability in humid and hot environments. Additionally, carbon paste can be utilized in situations requiring functional high-resistance electrodes or wiring.
In the creation of laminated wiring and other applications requiring sintering processing, copper ink is also used. Moreover, the wide choice of materials dispersed in binder resin, such as conductive polymers like PEDOT, is a feature of silk screen printing.
In printed electronics where it is important to control and ensure the resistance value between the wiring and the substrate, besides using PI, PEN, or our CRISPER® KAMISHINE® series
(rPET with incredibly low dk/df values) another advantage of silk screen printing is the ability to increase the thickness of the ink film compared to other printing methods such as gravure and inkjet.
III. Applications of Electronic Components Manufactured by Silk Screen Printing
Electronic components manufactured by silk screen printing are used for various purposes. Silk screen printing can print on some three-dimensional surfaces, so it can be printed without any problems on the rear glass of cars. (The anti-fog heating installed on the rear glass of cars is processed by silk screen printing. The electric heating wire printing uses copper paste.)
Besides, in the field of consumer electronic devices, sensor components such as touch screens and pressure sensors, multilayer ceramic capacitors, multilayer inductors, and other electronic components, and in the medical device field, silk screen printing is used in the printing process of carbon electrodes for sensor strips used in blood glucose meters.
For the manufacturing of electronic devices that require smaller, thinner, lighter, and lower prices, silk screen printing is the most suitable manufacturing method. In inventory management and sales management, the demand for UHD-RFID tags and other cheap and massively needed electronic devices is expanding, and the use of silk screen printing is expected to further expand in the future for products made using our company's CRISPER® TEONEX® and others, such as NFC transit cards.
IV. Future Directions of Silk Screen Printing
Silk screen printing technology is still evolving and will be used sequentially in new electronic devices. For instance, in stretchable electronic devices (stretchable electronic devices).
In recent years, the development of wearable devices that can be worn on the body like clothes has become increasingly active in the medical and healthcare fields. Wearable devices require elastic wiring that stretches with body movements, but general metal wiring cannot cope with this kind of stretching, so it is easy to break. Therefore, our company and its partners are advancing the development of flexible and conductive wiring solutions created through silk screen printing
(i.e., TOYOBO COCOMI®; for details, please contact C&T).
A characteristic of silk screen printing is the high degree of freedom in printing materials. The conductive ink of silk screen printing consists of binder resin and conductive filler. By increasing the flexibility of the binder resin and forming a printed film with dispersed resin layers that can maintain contact points of conductive particles, a wiring pattern that is both stretchable and conductive has been realized.
In the near future, wearable devices developed through silk screen printing wiring processing can be so small that the end-users will not notice them. References:
Batet, D., Vilaseca, F., Ramón, E., Esquivel, J., & Gabriel, G. (2023). Experimental overview for green printed electronics: inks, substrates, and printing techniques. Journal of Green Printed Electronics, 1(1), 1-15. PDF
Jaiswal, A., Kumar, V., Jansson, E., Huttunen, O.-H., Yamamoto, A., Vikman, M., Khakalo, A., Hiltunen, J., & Behfar, M. (2023). Biodegradable Cellulose Nanocomposite Substrate for Recyclable Flexible Printed Electronics. Advanced Electronic Materials, 9(1), 1-12. PDF
Jung, H., Lee, W., & Kang, J. (2022). Recent Progress in Printing Conductive Materials for Stretchable Electronics. Journal of Flexible Printed Electronics, 1(2), 137-150. PDF
Ozcan, A., Kandirmaz, E. A., & Coskun, S. (2022). Investigation of the effect of speed and pressure on conductivity in inkjet printed electronic devices. GRID Conference Proceedings, 2022(1), 43-50. PDF
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