Taking the accuracy of printed electronics below 1um

Printed electronics technology is evolving. A development direction is ultrafine line printing, increasingly allowing the technology to encroach into the realm of photolithography. The example here, developed by VTT, demonstrate a process for sub-micron printing.

The process is reverse offset printing. Here, the PDMS roller is first coated with the ink. The ink semi-dries on the roller, partially through absorption into the PDMS. This semi-dried state allows one to overcome wetting-related issues when inks are in liquid state. The inked PDMS roller is brought into contact with a Cliche, or relief plate, removing parts of the inks. The patterned semi-dried inks on the PDMS roller are then transferred onto the final substrate.

In this example VTT achieves 1µm direct printing of silver nanoparticle inks. The desktop RO printer was used to print a metal mesh on PET with 1µm linewidths. The reported sheet resisitivty is not very low (100Ohm/sqr), probably because the lines are very thin.

In general, note that ROP can enable minimum resolutions between 0.5-5µm, printed thickness lines around 20-1000nm, overlay accuracy <2um, and printing speeds of 50mm/s (3m/min).