The conductive inks business is a growing concern, offering both risk and opportunities. According to Research and Markets, the conductive ink and paste market will reach $2 billion in 2014. The market includes both mature and emerging markets with rapidly changing landscape, and an overall predicted 3.2% CAGR over the coming decade. A combination of the right technology and the right marketing strategy is needed for success.
What are conductive inks made of? There are three main components: a polymer binder, a conductive material, and a solvent. After printing, the solvent evaporates, leaving a conductive pattern on a substrate. The materials conferring conductivity to the inks include particles of silver, copper, carbon, and conductive polymers. The applications for conductive inks and pastes are many: touchscreens, photovoltaics, automotive, medical, RFIDs, sensors, and batteries. The current tendency is toward inkjet printing and thin lines, which makes silver nanoparticle inks more and more popular. Other inks and pastes include silver and copper flakes, copper nanoparticles, graphene and carbon nanotubes, PEDOT (polyethylenedioxythiophene), and silver ions and nanowires.
Conductive inks containing silver nanoparticles are characterized by high conductivity, enhanced flexibility and can be screen- or inkjet-printed. Only a few days ago at the Printed Electronics Europe 2014 Conference in Germany, DuPont Microcircuit Materials presented new developments in nano-silver screen-printable ink for Organic Light Emitting Diode (OLED) lighting and other printed electronics. The new ink is intended to make OLED manufacturing process simpler and less expensive. According to an article in Printed Electronics World:
DuPont anticipates that new nano-silver conductor ink materials will be commercially available next year and that these materials will be able to provide a combination of extremely high conductivity and excellent adhesion even after substrate cleaning steps. In addition, it is expected that these new inks would help enable the combination of low print thickness and smooth sintered surface necessary for OLED and optoelectronic applications where deposition of subsequent layers is required.
The nano-silver conductive ink by DuPont will be compatible with both glass and polymer substrates, such as polyimide, polyethylene naphthalate and polyethylene terephthalate, that provide a flexible foundation for OLED lightning panels and flexible printed circuit boards. Other printed electronics from DuPont include a membrane-touch switch, RFID, biosensors, and wearable electronics applications.
DuPont is not the only company to develop conductive silver inks for printed electronics. For example, Creative Materials offers several silver screen-printable inks for a variety of applications including EMI/RFI shielding of polyimide flexible circuits and membrane switches. In addition to screen printing, the inks can be applied by pad printing, flexography, and rotogravure, are resistant to scratching and flexing, and can adhere to a variety of substrates, including glass, polycarbonate, polyimide, polyester, ITO (Indium Tin Oxide), Teflon, and silicone.
Methode Electronics company (pdf) specializes in nano-silver (and nano-carbon) inks for inkjet printing applications and offers a developer kit to create and verify your designs using a thermal inkjet desktop printer. All it takes is replacing the regular printer cartridge with an inkjet silver cartridge!
Reactive Silver Inks
Some silver inks are actually particle-free. They are called reactive silver inks (pdf) and contain diamine silver complexes, from which silver particles are created on a substrate after printing (upon drying or heat-annealing). Reactive silver inks can be inkjet-printed and sprayed by airbrush.
An interesting hands-on application for everyone is writing or drawing and electronic circuit with conductive ink. A startup company called Electroninks has come up with Circuit Scribe, a water-based quick-drying reactive silver ink, with which you can draw a circuit of your own on regular paper:
From educational fun in classrooms to most advanced technological touchscreens and OLEDs, conductive inks make it possible! Want to learn more? You might want to look into a seminar, “Thick Film Technology,” which is coming up May 6-7, 2014.
Image by germina/123RF.
Source: “Research and Markets: Conductive Ink Markets 2014-2024: Forecasts, Technologies, Players,” reuters.com, April 4, 2014.
Source: “Conductive Ink Markets 2014-2024: Forecasts, Technologies, Players,” researchandmarkets.com March 2014.
Source: DuPont Microcircuit Materials, dupont.com.
Source: Printed Electronics Europe 2014, idtechex.com.
Source: “DuPont Shares New Research on OLED Lighting,” printedelectronicsworld.com, March 26, 2014.
Source: Conductive Silver Inks, creativematerials.com.
Source: Methods Electronics. Nano-Silver and Nano-Carbon Inks, methode.com.
Source: Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) conductive ink, sigmaaldrich.com.
Source: “Reactive Silver Inks for Patterning High-Conductivity Features at Mild Temperatures,” by S. Brett Walker and Jennifer A. Lewis, Journal of the American Chemical Society, 2012, 134 (3), pp 1419-1421; DOI: 10.1021/ja209267c.
Source: Electroninks, electroninks.com.
Video: “Circuit Scribe: Draw Circuits Instantly,” by Electroninks, YouTube.