Electronic devices could be made more cheaply and with less of an impact on the environment using a circuit-making technology based on inkjet printing, says Japanese electronics firm Epson.

The technique is based on the method used by inkjet printers to apply ink to paper. Instead of applying ordinary ink, Epson's inkjet circuit printer either fires droplets of conducting "ink" or insulating "ink" onto a circuit board.

By printing multiple layers of conductive and insulating ink, it is possible to make simple electronic components such as transistors.

At a press conference in Tokyo on Monday, Epson announced that it had used a prototype inkjet device to make a circuit that is 20 millimetres square, 200 microns thick and consists of 20 individually printed layers. Each line printed on this board is just 50 microns wide and 4 microns deep.

Epson say this is the smallest and most complex inkjet-printed circuit it has made to date, and the company believes it will in future be possible to manufacture inkjet-printed circuits with individual components measuring just 15 microns. This is similar in scale to much of the circuitry found in electronic devices such as mobile phones and PDAs.

Currently most electronic circuits are made using photolithography. This involves chemically etching a circuit onto a substrate using a template and photo-responsive chemicals. But it is a costly and complex process and also produces many waste materials.

Epson estimate inkjet-printed circuits should be about half as expensive to make as current circuitry and also less environmentally harmful. The company also aims to commercialise the technology by April 2007.

But circuits are currently made in huge volumes, meaning the success of the idea will depend on how well the new technology can be scaled up.

Will Knight
NewScientist.com news service