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Electroninks Offers a Variety of Particle-Free Metal Inks for Printed Electronics

The particle-free Cu, Ni, Ag, Au, and Pt conductive inks are metallo-organic-based and provide increased performance over typical nanoparticle-based inks.

Cabe Atwell

October 4, 2022

6 Min Read
Electroninks.jpg
Image courtesy Electroninks via LinkedIn

Texas-based 3D printing materials startup Electroninks announced the availability of its proprietary line of particle-free metallo-organic-based inks available to consumers. The announcement comes after receiving venture capital funding in February from intelligence community firm In-Q-Tel, which was founded by the CIA to combine cutting-edge technology and strategic investments to enhance and advance national security for the U.S. and its allies.

The inks are based on Electroninks's metal-complex chemistries, which are referred to as "particle-free" inks given their translucent nature. Particle-free inks provide a superior advantage over conventional nanoparticle inks and pastes that have been the primary option for metallization in printed electronics. The chemistry, inspired by precursors used in vacuum deposition techniques, provides product designers and manufacturers new materials for printing high-performance circuitry and provides many advantages, including accelerating time to market, reducing costs, and increasing sustainability in the metallization process.

Electroninks's inks can be deposited using an aerosol jet printing process, which works by spraying out an aerosol, a suspension of tiny liquid droplets in the air, in a process similar to spray painting. Unlike spray paint, however, this aerosol is precisely deposited and supported by a series of steps to ensure a small, focused beam of material that can be deposited in a variety of patterns and layers. In the case of Electroninks's particle-free inks, the printing process involves jetting out an ink stream produced by ultrasonic or pneumatic atomization. Electroninks's Ag (Silver), Au (Gold), and Pt (Platinum) inks are specifically designed for ultrasonic atomization and, as such, produce a higher printing resolution over the conventional pneumatic atomization process.

This new advanced process of printing circuits, sensors, or interconnects with an aerosol jet printer provides increased flexibility, high conductivity, and reliability. The ink is concentrated in the atomization process, which removes the solvents during that atomization process and ensures an appropriate mass output. Because of this process, the particle-free Au ink can be printed at room temperature with a high mass output, which is critical when printing on conformal surfaces. The printed structure is then thermally cured at 300 °C for 1 hour to achieve the best possible electrical conductivity.

Similarly to the Au ink, Electroninks's Ag ink can also be processed at room temperature, making them ideal for printing on complex surfaces. The Ag ink provides 5-7 μΩ-cm resistivity while Au can provide 6 μΩ-cm resistivity, and given this low resistivity, the inks require fewer printing passes compared with conventional inks. Electroninks's products are available for use in high-volume, production-scale applications and can also be customized according to customer specifications. Design News had a chance to ask Electroninks's Cofounder and President Melbs LeMieux more about the new particle-free inks and what's on tap for the future.

Why do the metallo-organic-based inks provide superior performance and reliability compared with nanoparticle-based inks?

LeMieux: Unlike conventional nanoparticle inks and pastes that are dispersions of metal particles and organics, there are no polymers in metal complex inks. They are solutions of precursor chemicals similar to those used in the semiconductor metallization processes. Because of this, the resulting films from metal complex inks have higher metal purity and a more dense microstructure compared with conventional conductive inks. This results in higher electrical performance and much better reliability, which is critical for materials used in semiconductor packaging and mobility applications.

What other benefits do they offer?

LeMieux: Electroninks deliver a more cost-effective and efficient use of many of the noble metals through its particle-free ink formulations. Its particle-free silver ink delivers higher conductivity, flexibility, and cost-effectiveness, making them ideal for today's smaller, lighter, more highly functional electronic products. The company is the first to provide particle-free conductive inks in silver, gold, platinum, nickel, and copper. Through strategic partnerships forged with tier 1 global companies such as Applied Materials and Merck, Electroninks is able to meet customer demands for quality, reliability, and scale.

For which industries and target markets could they provide utility?

LeMieux: Our metal complex inks can be used in applications ranging from semiconductor packaging to electrodes in micro-LED and flexible touch panel displays to electric vehicles. We are an essential component to the additive manufacturing process. Electroninks's mission is to design and develop the highest-performing particle-free conductive metallic inks that can fundamentally change the way our customers develop new hardware technologies and improve manufacturing processes.

Will they help alleviate any supply or environmental issues with other materials?

LeMieux: Electroninks's metal-complex ink products reduce waste and improve sustainability on multiple fronts. These inks are developed from a variety of precious metals like copper, silver, platinum, nickel, and gold. The precious metals market has long been plagued by environmental concerns surrounding unethical sourcing practices and access limitations. Electroninks's particle-free inks can achieve the same or better performance as particle-based inks on the market due to the nature of the formulation, which doesn't include additives like surfactants, polymers, or binders that reduce the conductivity of printed films. As a result, Electroninks's inks result in the formation of dense and highly conductive films while using far less precious metal than particle-based alternatives, making Electroninks's inks more environmentally friendly and less sensitive to supply chain and pricing constraints on precious metals.

What concerns would engineers have about using particle-free Cu, Ni, Ag, Au, and Pt conductive inks, and how can they be addressed?

LeMieux: We have the ability to manufacture inks according to customers' specifications so that they can create innovative products that can change technology as we see it. We are very customer-focused in this sense. Electroninks developed the first and only true HVM particle-free metal complex ink on the market, enabling enhanced performance, lower costs, and application paradigms for conductive inks. The fact that we have already scaled the production of this ink in a facility already producing inks for semi and pharma customers is a big reassurance to our customers. Electroninks's patented formulations provide customers with a cleaner, more environmentally friendly product, which in turn allows them to use less and streamline manufacturing to ultimately reduce costs. Customers that are focused on ESG improvements would want to understand more about our products.

Regarding the YouTube video and image, does it show the same printing process that you describe below? Or is the video more of a desktop printing video?

LeMieux: Electroninks's inks can be deposited using an aerosol jet printing process, which works by spraying out an aerosol, a suspension of tiny liquid droplets in the air, in a process similar to spray painting. Unlike spray paint, however, this aerosol is precisely deposited and supported by a series of steps to ensure a small, focused beam of material that can be deposited in a variety of patterns and layers. In the case of Electroninks's particle-free inks, the printing process involves jetting out an ink stream produced by ultrasonic or pneumatic atomization. Electroninks's Ag (silver), Au (gold), and Pt (platinum) inks are specifically designed for ultrasonic atomization and, as such, produce a higher printing resolution over the conventional pneumatic atomization process.

This new advanced process of printing circuits, sensors, or interconnects with an aerosol jet printer provides increased flexibility, high conductivity, and reliability. The ink is concentrated in the atomization process, which removes the solvents during that process and ensures an appropriate mass output. Because of this process, the particle-free Au ink can be printed at room temperature with a high mass output, which is critical when printing on conformal surfaces. The printed structure is then thermally cured at 300°C for 1 hour to achieve the best possible electrical conductivity.

About the Author(s)

Cabe Atwell

Cabe is an electrical engineer, machinist, maker, cartoonist, and author with 25 years’ experience. When not designing/building, he creates a steady stream of projects and content in the media world at element14, Hackster.io, MAKE ─ among others. His most recent book is “Essential 555 IC: Design, Configure, and Create Clever Circuits.

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