Inkjet Printing Electronics and Optical Devices

Relatively recent efforts to employ inkjet technologies in the fabrication of consumer
electronics are slowly finding niche application. The potential of displacing large and expensive
pieces of electronic fabrication equipment and processes with seemingly appropriately scaled,
inexpensive alternatives is attractive. However, of course, the devil is in the details. Feature size,
accuracy, registration, reliability, and materials all have severe impacts on design rules,
processing, performance, and the types of devices appropriate to the technology. Here we present
a look at some of the materials and deposition challenges along with solutions developed at
PARC. The discussion will include the use of Xerox print heads as well as other print heads for
the developing of processes and materials used in creating electronic and optical
devices, the defining of printed features >10μm with ±1.5μm drop placement, and layer-to-layer
alignment accuracy. The materials characteristics of the generally complex functional fluids of
interest required for reliable jetting and device performance will also be discussed. Examples of
inkjet-fabricated integrated circuits, working displays, imagers, and RGB color filters for LCD
displays will be shared.

Our efforts toward exploring new modes of manufacturing and reducing costs have
focused on advances in high-resolution printing technology coupled with the maturing field of
solution processable electronic materials. In particular, we have concentrated inkjet printing
over other high-resolution printing methods, such as microcontact, screen printing, and others,
due to the wide range of compatible materials and its ability to easily register successive material
layers and existing structures. This does not rule out the use of potentially higher-resolution
patterning for the initial layer. The ability of inkjet printing to cover large areas while being capable of
producing features down to and exceeding 10um is very attractive. Potential success stories
reported in the industry thus far have been largely simple conductive pathways for electronic
interconnects, color filters for LCD displays, as well as the deposition of organic LEDs.
We will discuss some of the issues regarding capability and throughput in using inkjet print
heads in development and manufacturing environments and the tools developed for rapid
prototyping.

While the applicability of inkjet methods to printed electronics is promising, the ability to
accurately register small drops on a substrate is not the only requirement for producing robust
devices for consumer electronics. Each layer step in creating a working device requires the
development of processes and knowledge of all the interactions of new materials and interfaces.
The development of jetting material/print head combination is significantly complicated by the
material components which define the electronic or optical functionality as well as compatibility
with all the materials that make up the end device.

Please contact TechConnect2010@parc.com for more information.