Leveraging Kodak Flexo Technology to Print Touch-screen Sensors

Jim Hamilton
Sep 25, 2015

In a huge manufacturing building in the Eastman Business Park in Rochester, New York, Kodak is printing sensors that can be used in touch screens for tablets, computer screens, kiosks, and industrial equipment. The process uses technologies that print service providers will find familiar, but they are being used to achieve a very different end result.

First, a series of flexographic plates are imaged on a modified Creo square-spot plate imager. Each plate has a repetitive design of extremely thin parallel lines. The plates are mounted on a modified roll-fed flexographic press that prints with a catalytic ink on both sides of a roll of clear plastic (similar to the material used for motion picture film). The catalytic ink provides a receptive surface for the next step, in which the printed roll of plastic is immersed in a bath with a copper fluid solution. In that bath, copper is applied to the thin printed lines of catalytic ink. The copper is what makes the resulting print conductive, and that’s why you can make touch screens with this printed component. A darkening agent is applied on top of the copper, and the rolls are then cut into sheets containing the functionally printed sensor that will ultimately go into a touch-screen display. This printed grid of thin, crisscrossing lines is virtually invisible, yet it provides the underlying conductive foundation that is able to sense when someone puts a finger on a touch-sensitive screen.

Kodak touch-screen sensor (showing a magnified view of the touch-sensitive grid)

Today Kodak is printing working production samples that can be tested by prospects who may one day use them in consumer electronics or other devices. The process, which Kodak describes as ‘additive,’ has some advantages compared to ‘subtractive’ methods of producing these touch-screen sensors. One of these advantages relates to the use of copper. Subtractive methods ‘ablate’ (i.e., etch away) the conductive material to reveal the fine grid. You can imagine how much copper is ablated away in a subtractive scenario. An additive method, where copper is only placed where it is needed, makes much more effective use of the copper. Kodak believes that their additive method also provides more effective conductivity. There’s one more reason why Kodak believes its additive technology will succeed. A popular implementation of the subtractive method is dependent on a process using indium tin oxide (ITO). One of the core components used in the ITO process is indium, a rare metal. According to Kodak, supplies of indium are dwindling and therefore other processes will ultimately need to replace ITO. Kodak expects its additive copper mesh print method to be a strong contender to replace ITO methods.

Kodak uses the acronym FPPF (flexo print and plated film) to describe their additive process for producing these touch screen sensors. This process builds on Kodak’s expertise in three key areas: deposition science, materials science, and image science, but what’s fascinating is the role that printing, specifically flexography, plays in this copper mesh process that Kodak has such high hopes for. This process uses devices that any flexographic printer would be familiar with, but unlike most printing, the result is a functional electronic sensor.

Kodak expects to get this initiative into full production with paying customers before long. Its prior partnership with Unipixel (a supplier to the touch screen and flexible electronics markets) has ended, but Kodak still has high hopes for the process and the resulting products. The building in Rochester where this is happening is the same industrial park where Kodak manufactured huge amounts of analog film in the past. Now the possibility exists for Kodak to play a central role in touch-screen displays with a 21st century technology.

InfoTrends has covered other functional and industrial printing topics (such as textile printing) through its Functional & Industrial (FIPS) advisory service.

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