RadTech 2012 examines role of UV in PV, printed electronics

By David Savastano • Editor

Industries and researchers alike are finding that energy curing technologies often have significant advantages in manufacturing their products. For manufacturers of printed electronics (PE), energy curing is proving to be a successful process.

To meet the interest in these fields, RadTech 2012 hosted two sessions of interest to printed electronics manufacturers. Photovoltaics & Electronics looked at key developments on the raw materials and electronics side, while Barrier Coatings & Conductive Films For Flexible Electronics looked at the need for improved barrier properties.

There were four talks during the Photovoltaics & Electronics session, moderated by Dr. Mike Idacavage of Esstech, Inc. Dr. Tokuji Miyashita of Tohoku University opened the track with Fine Pattern Drawing in Polymer Hybrid Thin Film Assemblies, and Jonathan Shaw of Cytec Industries followed with Suitability of Energy Curable Oligomers and Monomers As Encapsulants in Photovoltaic Modules. Mr. Shaw noted that encapsulants act as an adhesive and as a shock absorbing layer in PV modules.

Presently, the thermoplastic or thermosetting film is laminated into the PV structure using a time consuming process requiring heat and pressure, but Mr. Shaw reported that UV curable materials will also meet the PV encapsulant performance requirements, including thermal cycling, high temperature/humidity exposure and weatherability, as well as reducing the time to assemble the modules due to UV’s fast curing capability.

Kurt Schroder of NovaCentrix followed with “Photonic Curing – Simulation and Applications. Mr. Schroder discussed the science behind photonic curing as well NovaCentrix’ conductive inks, particularly its copper oxide-based inks, which offer a significant cost advantage over silver-based inks.

Oleg Pishnyak of Kent Displays closed the track with his talk on Developments in Flexible Cholesteric Liquid Crystal Displays Based on Polymerization Induced Phase Separation Technique. Kent Displays is noted for a number of innovative products based on its cholesteric liquid crystal displays (ChLCDs), including the Boogie Board eWriter.

The company utilizes UV curing for its roll-to-roll processing on flexible substrates, and Mr. Pishnyak reported that tuning of radiation curable formulations can significantly affect the cholesteric liquid crystal’s (ChLCDs) ChLC optical, electro-optical, temperature characteristics and environmental robustness of the displays.

Barrier Coatings & Conductive Films For Flexible Electronics, also moderated by Dr. Idacavage, also featured four speakers. Dale Babcock, Sartomer USA LLC, opened this session with his presentation on Influences on Barrier Performance of UV/EB Cured Polymers. Mr. Babcock noted that UV/EB cured materials utilized as barriers against moisture vapor and/or oxygen gas has been an interesting area of study for many different markets, and discussed testing results of UV and EB materials.

Fatima Toor of Lux Research, Inc. provided an overview of the solar market with her talk on metallization pastes and solar technology. She noted that CIGS technology is on the rise, while amorphous silicon is expected to decline. She also discussed new technologies such as electronically conductive adhesives and the use of copper-based metallization pastes.

Ram Ramakrishnan of UniPixel Inc. presented his talk on UV Based Conductive Inks for Flexible Printed Electronics. A recipient of this year’s Emerging Technologies Award from RadTech, UniPixel manufactures printed conductors using UV inkjet ink technology. Mr. Ramakrishnan said that these flexible conductors are finding opportunities in the touch screen and flat panel display markets. Nizamidin Jappar of Kimoto Tech closed the session with his talk on Development of Conductive Polymer Film and R2R Coating Process.

Afterwards, Dr. Idacavage said that the two tracks covered a wide range of topics, from key raw materials to applications and end processes.

“The emphasis was on conductive films and inks, and it was a god mix of speakers from universities, raw material suppliers and end users, with several of our presenters discussing commercial applications,” Dr. Idacavage noted.