Ink-jet Technology

Epson ink-jet technology was used to produce these ultra-thin multi-layered circuit boards.

Using ink-jet technology to produce a circuit board reduces the amount of waste material and the number of stages involved, making it cheaper and quicker than traditional methods. While screen printing involves coating the entire material being printed on, and then removing what is not wanted, ink-jet technology allows the precise placement of the metal particles that are wanted. The ink squirted out by the printer contains copper or silver flakes dissolved in a carrier liquid which is printed onto the fibreglass. As the carrier liquid evaporates, the metal flakes coalesce forming the desired circuit.

It sounds straightforward, but Chris Williams of UK Displays and Lighting explains that one of the challenges of using ink-jet technology for the production of electronics is that a lot of the inks used can be chemically aggressive. It's important to find chemicals that won't rot the print-head and piping and that are not harmful to the people who handle them. Conversely, the ink-jet process shouldn't affect the ink. There are different methods of ink-jet printing and so it is important to choose the most appropriate for the application in question.

Different methods of ink-jet printing

For the printing of packaging, labels and barcodes, continuous printing is the most common method. A steady stream of charged ink particles are ejected from the print-head and since the ink is charged, electrodes can direct the stream onto the product when required or into the printer's gutter where it is collected for reuse. This is a reliable method for mass production because the continuous ink stream prevents the nozzles from becoming clogged.