Paul Patterson of Seiko Epson gave a brief insight into the company's history and expertise with printed electronics at the recent NanoTX conference in Dallas, USA, attended by IDTechEx. Seiko Epson is famous for piezo electric inkjet printing and it is this printing platform that the company is applying to printing electronic materials. Compared to flexographic printing for the alignment layer process in LCD manufacture, inkjet printing uses 76% less material, most of that saving is a reduction in clean solvents and gases. While IDTechEx sees a place for numerous printing technologies in this field, inkjet printing has been dominant given the ability to make every circuit different, making it useful for development and prototyping, the ability to have great control over the amount of fluid deposited and that product volume so far is sufficient for inkjet speeds.
Printed OLEDs to printed silicon
Notable in-the-lab achievements have been a 40" printed OLED demonstrated in 2004 to inkjet printed silicon thin film transistors with a mobility of 6.5cm2/Vs. The company has demonstrated inkjet printed features of 5 microns, but not yet as a commercial product. Seiko Epson has internally developed the "fempto" inkjet head which has the ability to print varying sizes of sub pico liter ink drops.
Size of ink droplet volume versus it's radius
Source:Seiko Epson
Products
Much of Epson's printed electronics know-how has been translated to reduce the cost of manufacturing electronics. For example, Seiko Epson developed inkjet printing of Low Temperature Ceramic Co-fired (LTCC) conductive materials, able to print 30 micron features and multiple layers, aswell as printing vias and dielectrics. This has been commercialised and sampled to customers through the Epson collaborator Koa. Koa was able to reduce the size of a circuit board from 35x31mm to 10.6x25.1mm by using inkjet printing rather than screen printing as they had been using. This saved the manufacturer considerable cost.
Seiko Epson has also installed inkjet printers to print connectors to chip bonding pads for flip chip bonding rather than more expensive wire bonding. Patterson also spoke about how Epson has supplied inkjet printers to Sharp which they use to print LCD colour filters at their gen 8 factory in Kameyama, Japan, reducing the cost of manufacture of LCDs of their Aquos displays. Epson even inkjet print micro lenses for optical fibre connectors.
Epson's strategy is not to offer off-the-shelf inkjet head and station solutions but provide targeted solutions to different industries.
e-reader
Patterson concluded by taking about some new developments and potential emerging products. That included a 13.4" e-paper display, which will add to the new range of larger e-reader products launched over the last few months (from Plastic Logic, Brother Industries and iRex Technologies). Epson plans to launch a product in the near future.
For more information, Paul Patterson will be presenting at the IDTechEx Printed Electronics USA 2008 event in San Jose on December 3-4. See www.IDTechEx.com/peUSA for details.
