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Customer Demands, New Innovations in Conductive Ink

According to a report from MarketsandMarkets, the conductive ink segment is projected to reach $3.91 billion by 2021.

Anthony Locicero, Associate Editor03.13.19

The global market for conductive inks, pastes and other materials is estimated by consultants at $2 billion, growing to nearly $4 billion by 2021. According to a report from MarketsandMarkets, the conductive ink segment is projected to reach $3.91 billion by 2021.

"We are seeing Metallograph continuous aluminum printing on flexible substrates finding utility in a wide range of areas including sensor circuits, safety interlocks, LED mountings, electrical small and large, fuses and RFID antennae," said Dan Harrison of IIMAK. "Early applications for Metallographwere dominated by short run, highly customized flexible circuits and devices. However, as designers realize the simplicity and cost advantages of Metallograph over other digital printed electronics applications. We expect growth in higher volume uses with this type of printing application."

"Applied Ink Solutions has received a lot in inquiries for flexible conductive inks and our chemists are developing an elongating silver-filled conductive ink," said Steve Toyama, senior sales representative. "We currently offer a very flexible silver conductive ink which can stand up to repeated motion."

Customer demands

"Customers demand low resistance, sharp continuous traces and no post-printing treatments (i.e. sintering)," said Dene Taylor of SPF-Inc.

According to Harrison, Metallograph offers a unique digital print solution which can deliver these required attributes.

"Al Metallograph can deliver 0.03 ohm/square resistivity right out of the printer with no post process necessary," he said, adding that cost is another "important consideration."

"Metallograph ribbons are priced at less than $0.01 per square inch, depending on volume," Harrison noted. "This is very competitive with silver IJ inks."

He referred to a study that Tampere University ran comparing thermal transfer and inkjet printing of RFID antennas.

"Both IJ and TTR have their strengths and weaknesses," Harrison said. "However, TTR did show a superior ability to print onto low-cost substrates and achieve equivalent performance to sintered silver inkjet without the sintering. Work is underway to improve the printability onto a wider variety of substrates, including Kapton and paper."

Taylor said customers also demand the reliability of using pure continuous aluminum for the conductor as well as high productivity and advanced reliability of production systems.

"As digital conductive printing is in its early stages, companies like SPF Inc., are offering assistance with the whole product design, materials, assembly, substrates, multilayers, adhesives and laminates as well as complimentary inks and coatings," he noted.

"We really now see customers demanding complete solutions rather than just 'Oh here you go. Here is a really conductive silver ink,'" said Kerry Adams, market segment manager for DuPont. "They need systems of materials and substrates that work seamlessly together and are reliable. They need design advice. They need help with prototyping and parts. The technology is demanding and customers need confidence that a materials supplier can supply all these things along with the capability of large scale consistent manufacturing."

C3Nano has been focusing "heavily" on optics and reliability – "two major obstacles that have prevented the widespread adoption of new materials to replace ITO" – according to Co-founder and CTO Dr. Ajay Virkar.

He said the company can now meet Tier 1 requirements for both reliability and optics.

"Our unique Nanoglue technology which engenders a nanoscale fused grid (Activegrid) upon coating and drying leads to the industry’s leading performance in terms of optics," Virkar reported.

"It is clear that printed electronics manufacturers must be convinced that any innovation will enhance the device, be competitive, and have a reliable global supply infrastructure," said John Hannafin, global product manager, Sun Chemical Advanced Materials. "We are seeing more inquiries for smart packaging, especially with regard to certain innovations, including the T+Sun Touchcode technology which demonstrates that the consumer brands need some form of interaction.

ChemCubed Chief Marketing Officer Christopher K. Booher listed four key features that customers seek:

Performance in conductivity;
Reliability in printing;
Flexibility of low sintering temperatures;
Compatibility for both materials and engineered process.

"Our success to date is due to our ability to provide our silver conductive and dielectric inks that have met or exceeded each of these needs," Booher said. "We offer our commercially available materials ready to use through a bundled printer solution, and also work with engineers for the specific application and printing equipment for custom inline processes.

Applied Ink Solutions' customers, according to Toyama, are looking for silver-filled conductive inks, carbon resistive inks, silver/silver chloride inks, silver-filled two-part conductive epoxy, radio-opaque inks, and UV curable dielectrics.

"Specialty inks and modified formulations are also in demand for the next generation of electronic applications and for specialized substrates," he said.

Recent innovations and/or products
NANOGAP recently developed ink jettable short nanofibers, according to Technical Director Frank Wallace.

"We have a unique conductive Z-axis dielectric to cover the entire membrane tail for moisture resistance, and can easily be connected in the Z-axis and not in the X and Y direction," Toyama said. "This UV dielectric replaces a second print of carbon ink which must be printed exactly over the silver trace while this one covers the whole tail."

C3Nano developed a "very high performing" ink series called "Onyx," per Dr. Virkar, "which demonstrates the best haze and lowest reflectivity at low resistance."

It is being adopted by various customers, he added.

Adams said DuPont continues to innovate and expand its product offering. The most recent example is the second generation of formable stretchable inks for in-mold electronics.

"This is now a full suite of conductors, dielectrics, encapsulants, and adhesives with improved formability and reliability for creating aesthetically pleasing electronic functionality on 3D surfaces whilst saving weight and cost," Adams noted.

The company also expanded its Intexar line of wearable electronic materials with Intexar Health – "an innovative versatile textile technology that delivers advanced wearable healthcare," he said.

A lot is going on with NovaCentrix's ink products, Chief Marketing Officer Stan Farnsworth said.

"Our Metalon HPS family of silver screen inks, JS-A series of silver inkjet inks, and PFI series of flexo inks are our most popular inks," he said. "These ink families include both water and solvent-based versions, versions for glass, polymer, or textile substrates, and a range of elasticity/flexibilities when fully cured. Conductive performance is as high as 4 milliohms/square (HPS inks).

"Also, we are about to post on our website the first set of ink products which are a result of our recent acquisition of the Intrinsiq Materials," the CMO continued. "These copper-based inks are a great match for polyimide and other substrates.

"Finally, our new roll-to-roll integrated inkjet print system is generating a lot of interest, and we have sold units in the US, Asia, and the EU," Farnsworth concluded. "This exciting platform is being used to produce a variety of high-performance electronics globally."

For Sun Chemical, some of the company's newest developments have come through acquisitions, Hannafin said.

That includes a licensing agreement with GGI Solutions and the National Research Council of Canada, which has led to the introduction of a new family of molecular inks for the printed electronics market.

"Based on ionic molecules processed through a reduction process, the new IPS family of products will offer a viable alternative to conventional polymer thick film conductive inks and serve as a low-cost alternative to nanomaterials," Hannafin said.

The company's partnership with Pulse 3D Systems allows Sun Chemical’s high-performance silver inks to be utilized in its new Fluidant 3D printing system for antennas and sensor systems used in a variety of molded plastic components for mobile phones, tablets, wearables and laptops.

"The acquisition of the proprietary technology of Transitions Digital Graphics, LLC, which features a compelling display solution now called SunMotion, brings an interactive visual experience to consumers and strengthens Sun Chemical’s strategic initiative in electronic packaging by providing exciting new solutions in point of sale advertising," the global product manager said. "Our EMD5800 nanosilver material for aerosol jet and inkjet systems continue to make strides in the market, expanding our nanosilver offerings beyond just the screen, gravure and flexo printing processes. In addition to providing the industry’s best performing low-temperature sintering properties, the unique chemistry of EMD5800 nanosilver inks offers long open life, superior jetting performance, and compatibility with most commercial and industrial print heads."

Sun Chemical is now offering an “IME Full Stack” where, according to Hannafin, both thermoformable and “able-to-be-molded” graphic inks, conductive and dielectric inks can be supported from a single source.

Sun Chemical recently launched its new Imagecure XV501T DI photo-imageable solder mask for laser direct imaging and direct imaging.

It is a liquid product "which dries via evaporation to provide a film that can be sensitized by laser, laser diode, LED, or UVDI exposure, Imagecure XV501T DI comes with resolution capabilities of 50μm (2mm) or less, exposure sensitivity of 80-200 mJ/cm², resistance to hot air solder leveling (HASL) processing, and compatibility with a range of nickel/gold and immersion tin chemistries," Hannafin said. "The most advanced solder mask for LDI and DI on the market, Imagecure XV501T DI provides excellent adhesion to, and encapsulation of copper tracks; is halogen-free; and compliant with the Restrictions of Hazardous Substances and Waste Electrical and Electronic Equipment Directives.

The Imagecure Soldermask product line – designed for screen printing, curtain coating, air or electrostatic spray – features 30-50μ solder dam capabilities.

"Recognized as a trusted solution for rigid printed circuit boards that have received global approval by OEMs in various markets, Imagecure Soldermask is available in a range of colors and halogen-free varieties," Hannafin said.

Per Booher, ChemCubed has been building upon its current commercial materials to yield improvements in both material and process capability:

Materials

Standard silver conductive inks have been extended in range of viscosity to qualify on several key brands of piezo inkjet printing heads (Epson, Ricoh Gen 5, Konica Minolta, Fuji Dimatix, and others);
New flexible silver conductive inks are being tested for capabilities that yield benefits in stretch-ability and improved adhesion to multiple substrates;
Dielectric ink line expanding for capabilities of substrate primer/adhesion promoter, multi-layer insulation/optical clarity, and flexibility for flexible electronics

Processes

Dielectric Templating: The company's patent-pending process that utilizes both materials and methodology to increase the z-directional height of printed conductive traces, yielding optimized conductivity under better-controlled resolution of trace widths;
Wide format/Roll-to-roll printing: Multi-layer/Multi-material continuous roll format up to 63” wide for larger trace circuitry or high volume parts (exploring concepts as a service bureau and potential commercial offering of a customized printer)

Below is a summary of the range of applications for Metallograph currently under development:

In the process of commercialization

Transparent light switches;
Chip-less RFID (taking advantage of the label printer capability to make every print different);
RAIN RFID distributed production

Prototypes and process assessment