Nanopowders can be printed on circuit boards

New Materials Asia, August, 2007

A joint research project from Kyoto University, Hitachi Chemical Co Ltd and Fukuda Metal Foil & Powder Co Ltd has developed a novel way to make nanopowders of copper and other metals that can be patterned on resin circuit boards using inkjet printing.

Inkjet printing of copper nanopowders to define circuit patterns is a simpler process than the transfer-printing technology now employed and it can be used to make thinner lines, the researchers say. However, existing nanopowders tend to agglomerate, and the heat treatment for baking off an anti-clumping polymer prevents inkjet technology from being used to define circuit patterns on the resin boards common for electronic devices.

With the new method for making metal nanopowders, the individual grains do not need to be coated with polymer so the inkjet printing process can be used to draw circuits on even resin boards.

The process starts with a powder of a metal oxide, which is mixed into organic solvents like acetone and then exposed to laser light.

Adjusting the laser conditions yields a nanopowder of the metal, with grains smaller than 100 nm in diameter and coated with a thin oxide layer. This oxide coating prevents the grains from gathering in a cluster without interfering with the ability of the metal to conduct electricity.

For further information, contact: Hitachi Chemical Co Ltd, 2-1-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo, Japan; tel: 81-3-3346-3111; Internet: www.hitachi-chem.co.jp/english; or contact: Fukuda Metal Foil & Powder Co Ltd, 20 Nakatomi-cho, Nishinoyama, Yamashina-ku, Kyoto 607-8305, Japan; tel: 81-7-5581-2161; Internet: www.fukuda-kyoto.co.jp; or contact: Kyoto University, Yoshida Honmachi, Sakyo-ku, Kyoto, Japan; Internet: www.kyoto-u.ac.jp