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Recent Development in Flexible Electronics
Chin-Chin Tsai
R& D Deputy Director of Flexible Electronics Technology Division,
Electronics and Optoelectronics Research Laboratories
Industrial Technology Research Institute
Hsin-Chu, Taiwan/Republic of China
Abstract and actuators.
Following the success of the semiconductor and flat
panel displays, Flexible Electronics is expected to Technology Challenge
become the next wave industry. The characteristic of Although the Flexible Electronics research and
Flexible Electronics is not only reduced production cost development over many years. Some products
and they have lightweight, thinner, non-breakable and successfully entered the market but there are still many
new forms to create many new applications. It can be technical challenges. Such as
leveraging Taiwan’s fast integration capability to create (1) Flexible substrate handling and alignment: the
new products and applications. The target industries are dimensional control of plastic substrate is very difficulty
flexible AMOLED displays and electronic papers, due to temperature, humidity and tension variation,
flexible lighting modules with LED, flexible special, roll-to-roll operation.
photovoltaics, flexible pressure and touch sensors, and (2) Organic materials film formation quality: the
flexible speakers, and so on. In addition, there are film morphology is not easy to control due to
developments of related materials, processes, facilities solvent-effect, the long-chain molecular configuration,
and scenario prototype products. Taiwan's industry had and processes conditions.
built an electronics paper supply chains, will drive rapid (3) Flexible conductor conductivity and work
development of eReader market. The real color of the function: the operation flexible and conductivity is the
electronic paper and soft products will appear soon in the trade-off parameters, and work function always needs to
market. High differentiation of flexible sensors, speakers modify.
and lighting sheets are developing markets. (4) Printing quality: the printing qualities (thickness,
register, trace and function) are not easy to control due
Introduction liquid off-set or jetting operations, special, multilayer or
The Europe countries reviewed the competitiveness large-area film printing.
of semiconductor and flat-panel display industrials, and (5) Flexible operation: the practice flexible
found only a few companies is important player. They operations (bending, foldable or rollable) is not east to
decided to develop Organic Electronics as a future guarantee due to stress of multilayer structure. And most
industry because they have the most powerful of the important, the user operation behavior is not predictable.
organic chemistry and materials industries. And then, (6) Infancy quality and price: for an exist product,
Organic Electronics was combined with printing the benchmark is difficulty reached.
technology to reduce the production cost. It was called
Printed Electronics. As the organic materials and printing Status of Technology and Industrial
technology is very suited manufacturing on the flexible The research and development in Taiwan is focused
substrates, specially, high throughput roll-to-roll on big markets, nearly markets, and differentiation
processes. The characteristic of Flexible Electronics is markets. The sector of big markets includes active-matrix
not only use organic materials, printing processes and organic light-emitting diode (AMOLED) flexible display,
flexible substrates to reduce production cost and they LED-based flexible lighting module and flexible
have lightweight, thinner, non-breakable and new forms photovoltaics (organic solar cell, dye-sensitized solar cell
to create many new applications. The applications of and CIGS solar cell). The sector of close to markets
Flexible Electronics can be divided into four areas, includes printed RFID antenna, flexible backplane with
namely, electronic circuits and memory, displays and electrophoretic display (EPD), and cholesteric liquid
electronic papers, solar cells and batteries, and sensors crystal (Ch-LC) flexible e-paper, and R2R touch sensor.
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The sector of close to markets includes flexible speaker roll-to-roll screen printer. Characteristic of flexible sensor
usage electret membrane and flexible pressure sensor. In is high linear relationship between pressure and
addition, there are developments of related materials, conductance. It does not need a complicate firmware and
processes, equipments and scenario prototype products. system, so production cost is very low. In addition, this
Development strategy of Flexible Electronics is sensor could easily make a large-area sensor array. A
depended on global technology progresses and market cheap, flexible and large-area sensor array has many
forecasts. For example, ITRI has been developing applications, such as, user-interface, weight scales, and
organic thin-film transistor (OTFT) technology. It was so on. ITRI develops and demonstrates many
planned to apply into the printed logic circuit at the applications, includes the scalar of luggage, musical
original target. But its performance is not good due to instrument, pressure bed, light controller, racing chair
low mobility materials, poor printing technology and bad and touch bottom of portable electronics. This
device uniformity. So it is changed to develop of OTFT technology has licensed to UCC, it is building a mass
array, and apply into flexible display backplane. Some production plant.
enabling creative technologies will be introduced as Flexible Speaker
follows: ITRI develops a large-area flexible speaker and
Electronics Paper receives winner of Wall Street Journal Technology
˧ˠ
Currently the most successful technology and Innovation Award at 2009. FleXpeaker is made by
industry is electronics papers, the main applications are electret film, so that the driving voltage is lower than
eReaders, electronics shelf labels, smart cards, electrostatic speaker. The key technology of ITRI is
electronics posters, and so on. The biggest business is developing a special electret material and device
˧ˠ
eReaders, the almost is supplied from Taiwan's structure, allowing FleXpeaker to be produced using
manufacturers. E-ink Holdings invested in E-inks and partially roll-to-roll processes.ʳ Characteristics of
˧ˠ
AUO invested Sipix to get electrophoretic display media FleXpeaker are lightweight, thinner, flexible, low
(EPD), combining with their strong manufacturing power consumption and can be used any shape. In
abilities to supply EPD modules. Detla Electronics and addition, its' audio performance is excellent in the middle
Brdigestone cooperate to develop a colorful electronics and high frequencies.ʳ A cheap, flexible and large-area
papers (QRLPD) to replace black/white EPD media. speaker can be replaced in almost all the traditional
Many colorful technologies are developed Industrial and speaker. Special, large-area is a interesting application.
ITRI. Sollink (Qualcomm and Foxlink joint venture) ITRI demonstrates a 0.5mW2.5mH speaker sheet, it
develops IMOD colorful technology and ITRI develops can be used as part of decorating. Taiwan Electrets
cholesterol liquid crystal and electrowetting technologies.ʳ Electronics is a spin-off company from ITRI. It has
Currently the eReader is not really flexible because it use already started to sale super-thin speakers.
a glass backplane. E-Ink Holdings and ITRI demonstrate
the flexible backplane and flexible papers. The backplane Conclusion
technology of E-Ink Holdings is used silicon transistors Taiwan's industry built an electronics paper supply
on the polyimide substrate. The technology of ITRI chain, will drive rapid development of eReader market.
includes organic semiconductor and printing process, The real color of the e-paper and soft products will
substrate is PET films which only can be processing at appear soon in the market. High differentiation of
low temperature. ITRI also develops a passive flexible sensors, speakers and lighting sheets are
technology of cholesterol liquid crystal which can be developing markets. Taiwan has continued to strengthen
manufacturing using a fully roll-to-roll process. research and development to promote industrial
Flexible Sensor development, to achieve missions.
ITRI develops a flexible fully-printing pressure
sensor and receives runners-up of Wall Street Journal
Technology Innovation Award in this year. This flexible
sensor is a piezoresistive-type that the resistance is linear
with pressure. The key technology of ITRI is developing
a special piezoresistive material and robust device
structure, allowing flexible sensor to be produced using
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