Thursday, March 27, 2008

Cheap Copper Nanograins Enable Circuits To Be Inkjet Printed

Thursday, March 27, 2008

TOKYO (Nikkei)--A research team at the Nagaoka University of Technology has developed a low-cost way to synthesize nanograins of copper that resist oxidization.

The availability of an inexpensive copper nanopowder of this type would enable wiring on circuit boards to be fabricated using inkjet printing. This would ease the process and eliminate the need for etching, which creates waste liquid.

According to the university group, the process can make copper nanograins for just a 10th the cost of existing methods. The team will continue their research in cooperation with the private sector and hopes to have a practical version of the technology ready in fiscal 2012.

Copper nanograins are currently made in an energy-intensive process that involves evaporating copper by placing it on a heater. In the new procedure, a fine copper wire is subjected to around 6,000 volts for several microseconds, instantaneously heating it to several thousand degrees C and evaporating the copper. The metal vapor is immediately cooled by a mixed gas of nitrogen and oleic acid to form nanograins of copper coated with oleic acid, which protects the metal from oxidation.

By adjusting such factors as the pressure of the cooling gas, these copper nanograins can be made in sizes ranging from 5-70 nanometers. Once made, the nanograins are recovered using filtering and liquid separation.

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