Consumer Peripherals

Conductive ink and its applications

01 February 2024
Conductive ink paper circuit. Source: Veraganis/iStock

Conductive ink has changed the understanding of circuits and connections since its invention in the early 1900s. To create functional circuits on a variety of surfaces, including paper and fabric, conductive ink is an excellent material to use. Paint products that can conduct electricity have also been developed by some companies in addition to inks. Conductive paint, which functions similarly to conductive inks, has a wide variety of uses, including as a cold solder, for repairing printed circuit boards (PCBs) and more.

Conductive tracks and electrodes are essential to electronic circuits, and materials like silver can be transformed into ink or paste that works with different printing methods. The printing of conductive circuits on paper or plastic then becomes possible, with performance comparable to that of conventional circuits based on copper. As a result, this ink is useful in vital sectors like the military, where it helps advance printed circuit technology for electronics. Its incorporation into mainstream technology began with this crucial role.

How conductive inks are manufactured

Conductive ink usually consists of conductive particles dispersed within a liquid medium, which can be either water or organic solvents. These conductive particles can be crafted from a range of materials including silver, copper or graphite. The selection of material hinges on the particular application and the desired properties of the ink.

The manufacturing process involves a meticulous formulation of the ink, striving for the optimal balance of conductivity, viscosity and adhesion. The conductive particles undergo a fine milling process and are dispersed within the liquid medium, creating a uniform mixture. This resulting ink is then applied to a substrate using diverse methods like screen printing or inkjet printing.

Applications in electronics

Because it is both flexible and inexpensive, conductive ink has replaced traditional rigid circuit boards in many electronic devices. This ink has been instrumental in the development of smart textiles and is commonly used to make flexible and wearable electronics. Because of its extraordinary adhesive capabilities, it can be used to create complex circuit patterns on non-standard substrates.

Moreover, conductive ink plays a crucial role in crafting radio frequency identification (RFID) antennas, touch sensors, and is even making strides in the emerging field of 3D-printed electronics. Its versatility extends well beyond conventional circuitry, fostering innovation in the design and manufacturing of electronic devices.

Different types of conductive inks

A variety of conductive inks is available, each designed for a particular use:

1. Silver-based conductive ink: Known for its high conductivity, silver ink is widely used in applications requiring superior electrical performance. For example, these inks are often employed in the production of flexible and wearable electronics and are suitable for creating intricate circuit patterns on flexible substrates, such as textiles or polymers. Silver inks are also used for printing RFID antennas, as the high conductivity of silver ensures efficient communication in RFID systems.

2. Carbon-based conductive ink: Carbon ink, often containing graphite or carbon nanotubes, is preferred for its flexibility and lower cost, making it suitable for wearable electronics and flexible substrates. The flexibility of graphite suits uses where the substrate may undergo deformation. Graphite-based inks are also used in the development of biosensors for medical applications. The ink's biocompatibility and conductivity make it ideal for integrating sensors into biological systems. Such inks are also popular in educational and do-it-yourself (DIY) projects due to their accessibility and ease of use and can be included for simple circuit prototyping on paper or other substrates.

3. Copper-based conductive ink: Copper ink offers a balance between conductivity and cost, making it a popular choice for various printed electronics applications. They are often used in the production of traditional PCBs and are a cost-effective choice for standard circuit board applications. In educational settings or prototyping labs, copper-based inks are a more budget-friendly option for experimenting with printed electronics. Therefore, they are suitable for applications in consumer electronics where cost considerations are essential, and the conductivity requirements are moderate.

4. Stretchable inks: The increasing demand for e-textiles and in-mold electronics has contributed to this new advancement. Although the ink only needs to endure a single elongation event in the in-mold electronics application, it must endure multiple substantial stretching events in the e-textile and related industries. New materials have been developed by suppliers in response to the emergence of both of these applications.

[Find suppliers of conductive inks on GlobalSpec]

Conclusion

The discovery of conductive inks paves the way for novel ideas and useful applications such as the development of flexible applications, the incorporation of electronics into wearable clothing, or the production of affordable RFID antennas. Silver-based inks shine in high-performance and flexible electronics, providing superior conductivity. Copper-based counterparts strike a balance between cost and performance, finding their niche in traditional PCBs and consumer electronics. Meanwhile, graphite-based inks offer flexibility, making them ideal for stretchable electronics and biosensors.

To contact the author of this article, email GlobalSpecEditors@globalspec.com


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