Conductive ink for printed circuitry

Dominique Schroller

Published on 08.07.2020

A technological start-up from London has developed conductive ink, enabling a more creative approach to working with electronics

Conductive inks and paints first came to market in the mid-1980s. Since then their main area of application has been in the manufacture of printed electronics, especially circuit boards. Almost every electric device we use relies on them. However, improved formulae and innovative manufacturing methods have opened up a whole new range of applications in the meantime. The rise of smart products, in particular in the home or in the field of smart clothing, has increased demand considerably.

The conductor is the key

When it comes to electronic inks, the choice of conductor is the key factor. The most widely used products are based on carbon, graphite, copper or silver. Copper and silver inks are highly conductive but often contain solvents to preserve the suspension. As a result, they frequently take longer to harden when being applied, meaning that you need good ventilation to prevent exposure to toxic vapours when using them indoors. Furthermore, metal-based inks contain particles that can drop out of the solution or oxidise, thereby shortening the service life of the printed circuit. Such conductors are also significantly more expensive and thus often uneconomic for use on a large scale. Graphite is cheaper in direct comparison to metallic conductors such as silver or copper and is also available in larger quantities. The only important thing to remember is that graphite has a higher specific electrical resistance, which results in a slightly lower conductivity. 

Electric paint as a user-friendly alternative

Most conductive inks or paints are designed for industrial use and only rarely available in small quantities. To enable designers and engineers to produce printed circuits on a small scale, e.g. for prototypes, Bare Conductive has developed a water and graphite-based conductive ink together with electric paint. It is non-toxic, water-soluble and can be used to produce small printed circuits and capacitive sensors.

Electric paint is a combination of soot and graphite in a water-based solution. The ink dries in the air at ambient temperature and can be applied with a brush, roller, or spray-gun, using a template or by silk screen printing on most nonconductive materials. It does not have to be hardened separately. The water contained in the electric paint evaporates while the ink is drying, leaving conductive particles on the surface.

Images: Bare Conductive