Industrial + Specialty Printing

This article demystifies the expansive landscape of printable nanomaterials and describes their many uses in modern applications.

By Alan Rae

Nanotechnology and printed electronics are business and technology areas that have been hyped mercilessly in the last 10 to 15 years, with the promise of markets of literally trillions of dollars and the opportunity to give a shot in the arm to traditional industries suffering great structural change, such as the printing industry.

A lot of money has been thrown at nanotechnology worldwide—nearly $2 billion this year in the U.S., according to the National Nanotechnology Initiative, with matching funds in Asia and Europe and an equivalent amount again being spent by industry. Most of the government funds in the U.S. have gone to universities and to set up outstanding National Science Foundation centers, such as the Center for High-Rate Nano Manufacturing (www.nano.neu.edu), small-business grants have stimulated partnerships and spinoffs, and there has been groundbreaking work in developing new materials and systems.

The new-materials businesses, like many others, did not escape the recession—many went down. The intellectual property (IP) they generated, however, is being regenerated in new ventures and in larger companies that bought the IP or the small companies. Pixelligent is one company that made it out of Chapter 11 successfully, making nano-sized semiconductors to enhance LED performance.

Printing in electronics
There is a great deal of printing already in use in electronics, ranging from photolithography to screen printing. The target of roll-to roll printing has been hampered by materials issues and competition from other forms of circuit formation that are mature, low cost, and improved incrementally. Companies with great technology in roll-to-roll processing, such as Polaroid and Kodak, have created the technology base for companies such as Konarka to thrive in printed electronics—in Konarka’s case, in flexible solar cells.

The traditional route to circuit-board manufacture involves glass cloth impregnated by resin sandwiched between layers of thin copper foil, itself formed by continuously plating copper on a cylindrical electrode. The copper is patterned using photolithography and etched to produce conductive paths, and then the laminates are joined together with intermediate glass-epoxy layers, aligned and densified in laminating presses not unlike those used to manufacture plywood.

Layer-to-layer interconnections are drilled using mechanical drills or lasers and plated to form interlayer connections. The filling may be completed using further plating or screened conductive paste, and subsequent layers may be built up by sequential deposition of epoxy and copper patterns using photolithography.