X-MINING What is Conductive Ink? Exploring its Applications and Cost-Effective Solutions

This column explains the cutting-edge technology of conductive inks and their potential applications. Sumitomo Metal Mining’s Cu-Ni　complex ink achieves low-temperature sintering and high conductivity, promising applications in the printed electronics industry.

Conductive ink is a material that contains conductive substances mixed into a liquid form with solvents like vehicles. It’s used in the circuits and sensors of electronic devices. This technology allows us to print electronic circuits on both hard materials like alumina and flexible materials. It can also be used for resin film,like PET film, polyimide film,that require heat resistance. This improves how we flexibly design and make electronic devices.

As the Internet of Things (IoT) progresses, the demand for conductive properties in various applications has led to the ability to print conductive ink on diverse materials, opening up new possibilities in the design and manufacture of electronic devices.

Conductive inks can be categorized into several types: those that use metallic micro-particle fillers and binders (such as gold, silver, and copper), those with metallic nanoparticles and submicron particles as fillers, and those containing carbon-based materials (such as carbon and graphene) as fillers.In general, conductive inks using silver micro-particles and curable resins such as epoxy resin have been widely used, also called silver pastes due to their high viscosity. However, although resin-cured pastes can form circuits at low temperatures, their resistance is lower than that of pure metals because the metal particles contact each other through the binder, resulting in a small contact area between the metal particles, and the binder component also acts as an obstacle.

On the other hand, in inks with metallic nanoparticles or submicron particles as fillers, the particles bond with each other at low temperatures, so the resulting wiring has a larger contact area between metallic particles compared to resin-cured pastes. Depending on the sintering state, the wiring can be similar to a metal foil. Inks based on gold and silver nanoparticles have been actively developed in recent years as stable electronic materials that do not require high-temperature processes, are resistant to oxidation, and have high conductivity.

Conductive inks are used in a wide range of products, from consumer electronics like touch panels, flexible displays, wearable devices, and electronic paper, to automotive applications like sensors and anti-fog heaters, and industrial applications including various sensors and batteries. These inks enable the production of electronic devices with shapes and designs that were impossible with traditional manufacturing methods. With the growing prevalence of IoT devices, the demand for conductive ink is expected to increase further.

[Related article]What is Printed Electronics? Exploring its Applications, Practical Examples, and Future Potential

One of the main challenges with conductive ink is its cost. This is especially true for inks that use silver, even the rapidly increasing price of silver. There’s active research and development in conductive inks using copper and carbon materials as alternatives. However, achieving the same level of electrical properties as silver without its oxidation issues presents various challenges. For example, copper oxidizes more easily than silver, leading to stability issues in the ink that require specific measures to mitigate.

Sumitomo Metal Mining is developing a new conductive materials, MOD Paste (Metal Organic Decomposition Paste). , This paste consists of MOD ink with a highly manageable function and fine copper powder developed in-house, allowing it to be sintered at low temperatures and reduce resistance through thick film application. The MOD ink itself also functions as a conductive ink.

Compared to traditional copper nanoparticle inks, this new material offers improved oxidation stability and high conductivity at a lower cost. This makes it particularly suitable for large-area device applications where a substantial amount of ink is required.

MOD Paste (Metal Organic Decomposition Paste)[Material]

Sumitomo Metal Mining’s MOD Paste (Metal Organic Decomposition Paste), with its low-temperature sintering and thick film capabilities, is expanding the possibilities of printed electronics, contributing to the next generation of the electronics industry, including batteries and displays, and opening up new applications.