Ink jet printing is rapidly becoming an important manufacturing tool that will be increasingly significant in an era of manufacturing flexibility and product personalization. It is also a tool that can further increase the productivity of manufacturers by facilitating greater automation and a reduction in process steps. Ink jet technology will have a significant effect on the manufacturing sector by making manufacturing far more environmentally friendly and responsive to consumer needs. Without a doubt, this emerging technology will make an impact with its diverse applications that span far beyond traditional printing.
Today's ink jet printheads are capable of depositing (without contact) precisely placed, microscopically small drops of fluid. Heat is not needed to propel fluid from the nozzles of a printhead, so corrosive materials can be jetted without destroying the printhead. This means fluids like silver, gold, DNA and bacteria can be "printed" on a variety of surfaces, including plastic, metal sheets, glass, silicon and paper. In this way, ink jets can be used to print electronic devices like flat and flexible displays, RFID tags, flexible and rigid circuit boards, 3-D objects and more. Typically, electronic circuits contain electrical trace lines that are made through a photo masking and etch process. With ink jets, these trace lines are instead made by directly depositing conductive fluid where needed. This new process is faster and requires less material, thereby saving costs for the manufacturer.
Dr. Ghassan Jabbour, professor of materials science and engineering, and director of flexible and organic electronics development laboratories at Arizona State University, is already using ink jets to develop foundational devices for displays, photovoltaics, sensors and microfluidics. With an ink jet printer, he can print multi-layered patterns of gels, metals, conductive polymers and light-emitting organic materials. He recently printed metallic lines with resolution down to around 30-35 micrometers.
Another area of manufacturing in which ink jets will have a significant impact involves LCDs (liquid crystal displays). As LCDs have moved into TV format, substrate size has multiplied more than four-fold. Traditional methods of fabricating the polyimide alignment layer are not satisfactory for these new larger Generation 7 or Generation 8 glass substrates, but ink jets can deposit this layer quickly and uniformly.
According to industry estimates, LCD color filters represent approximately 19% of the total cost of LCD manufacturing. Studies have shown that compared to traditional photolithography processes used in color filter manufacturing, ink jet technology can provide cost reductions of up to 40%. The same study showed that ink jet technology can further benefit color filter manufacturing by reducing materials usage by 20-30% and investment costs by more than 50%. (Study done by Kodak )
Other researchers are exploring the possibilities of ink jet printing RFID transistors using solution-processable organic conductors such as PEDOT (acidic water based conductive material.) Manufacturers in additional areas are considering ink jetting. For example, ink jets will improve production of color PLED (polymer light emitting diode) displays because traditional spin coating is useful only for monochrome displays. Many ink jetting manufacturing prototypes are already in place, and many more are sure to come in the near future.
A small ink jet fluid deposition system is ideal for R&D situations because it reduces the cost barriers of existing commercial pre-production and production ink jet printing systems, which cost upwards of $200,000. For instance, a group of developers is currently using the new fluid deposition system to qualify and compare fluids, test conditions for jetting, understand substrate test conditions and process conditions (e.g., how much the fluid will spread and whether heat will be needed.) The system's simplicity makes it easy to evaluate fluids and substrates for final properties and to print samples of new designs for evaluation. Because the system is table-top sized and intuitive to use, it doesn't take up floor space or need its own room or dedicated personnel or resources to get results. And once the critical R&D phase is complete, ink jet printing systems are scaleable to production and a great tool for the manufacturing industry.
According to research firm NanoMarkets, the ink jet printable electronics market is expected to reach over $30 billion by 2013. Because of the low cost and high flexibility of these systems, it's certain that we will be seeing cutting-edge innovations developed with ink jets on the market in the near future. Perhaps soon you'll be able to make a cell phone call by speaking into an electronic device embedded in the sleeve of your jacket; or maybe you'll access your computer via a flat-panel display so thin and flexible that it can be pulled down like a window shade; or you'll spot an RFID tag at the grocery store letting you know how fresh the produce is. However the technology is applied, it is clear that ink jet printers will revolutionize technology and the electronics manufacturing process.
Dr. Linda Creagh is business development director for the Deposition Products operation of FUJIFILM Dimatix, Inc. She has a number of technical publications and U.S. and foreign patents in the fields of ink jet technology and liquid crystal displays. Dr. Creagh holds a Ph. D. degree from the University of North Texas in Physical Organic Chemistry. For more information contact [email protected] or visit www.dimatix.com.