Roger Bollström, Daniel Tobjörk, Anni Määttänen, Peter Dolietis, Petri Ihalainen, Jouko Peltonen, Ronald Österbacka and Martti Toivakka

Center for Functional Materials and Department of Paper Coating and Converting, Åbo Akademi University, Turku, Finland

Towards Paper ElectronicsTowards Paper Electronics‐‐ A A multilayer coated fibermultilayer coated fiber‐‐based substrate suitable based substrate suitable for for printed functionality printed functionality 

The profitability of the global forest industry has been dismal in recent years, due to increases in raw material and energy costs, competition from electronic media andovercapacity in production of traditional paper grades. New value‐added products or existing products with novel functionality could be a way to improve the situation. Theadded value could be in form of e.g., sensors, displays or radio‐frequency identification (RFID) tags, which analyze product quality, show transport conditions or streamlinelogistics. In this area one of the trends is to develop low‐cost disposable electronics. For these to become reality, devices with reasonable electrical performance andpractically negligible production cost are required. One way to reduce the manufacturing cost is to fabricate the electronics on inexpensive paper substrates by using roll‐to‐roll techniques (“Paper Electronics”), as an alternative to conventional electronics manufactured with batch processes on glass or polymer film substrates.

Smoothing layer

Barrier layer

Topcoating

Structure of the substrate

Precoating (GCC)

RMS 580 nm

Smoothing layer (Kaolin)

RMS 300 nm

Barrier layer (Latex + filler pigments)

RMS 260 nm

Calendered topcoating (Kaolin)

RMS 55 nm

Washed Mylar® A RMS 30 nm

Basepaper

Precoating

Smoothing layer

Precoating

Smoothing layer

Barrier layer

Topcoating

AFM topography images (20 x 20 µm2) of the different substrate layers and Mylar® A plastic filmRMS roughness (100 x 100 µm2)

RMS 580 nm

SEM cross‐section images showing the structure of the multilayer coated substrate

PCT/FI2010/050056, WO 2010/086511, Bollström Roger, Määttänen Anni, Ihalainen Petri, Toivakka Martti, Peltonen Jouko

Mineral pigments‐Kaolin, PCC, GCC, Talc, Silica

Manufacturing methods

Blade coating

‐ Precoating

Reverse gravure  coating

‐ Barrier layer

Curtain coating

‐ Precoating

Binders and barriers‐Styrene‐n‐butyl‐acrylate (SA)‐Styrene‐Butadiene (SB)

Roll to roll hybrid printing of functional materials Barrier properties

g‐ Smoothing layer‐ Barrier layer

Functional printing Proof of concept

Barrier layer‐ Topcoating

Precoating‐ Smoothing layer‐ Barrier layer‐ Topcoating

H i I l Fi ld Eff T iH i I l Fi ld Eff T i

Flexography (source & drain)

Spray coating (semiconductor)

Unwinder

Spray coating (insulator)

Flexography (gate)

Mylar® A

References

Topcoating addedStora Enso

LumiartCopypaper

Precoating Smoothing layer

(Kaolin)

PCC Kaolin

Frontside

Backside

Frontside

Backside

10 mm

Barrier layer

(Latex)

Drop size5μl

Roll to roll hybrid printing of functional materials p pInk spreading vs ink penetration

Setup for printing transistors reel‐to‐reel

Infrared sintering

Hygroscopic Insulator Field Effect TransistorHygroscopic Insulator Field Effect Transistor

Digital camera picture of all‐inkjetted transistor 

Current‐voltage characteristics

Rewinder

0.0 -0.5 -1.0 -1.5 -2.0

0

-2

-4

-6

-8

-10

-12(W

=

10x2.5mm)

-0.8 V

-0.4 V

Dra

in c

urre

nt (A

)

Drain voltage (V)

0 V

VG= -1.2 V

0.5 0.0 -0.5 -1.0 -1.5 -2.01E-3

0.01

0.1

1

10

ID

IS

IG

VD= -1.5 V

Cu

rre

nts

(A

)

Gate voltage (V)

PQT-12

Source and drain printed with flexography. 

The silver ink is sintered online using IR radiation

Prin

t dire

ctio

n

2 mm

Prin

t dire

ctio

n

2 mm

Prin

t dire

ctio

n

2 mm

The surface properties of the topcoating layer can be tuned to meet the demands set by ink and printing method

• It is possible to create a paper‐based substrate suitable for printed functionality by utilizing recyclable, commercially available raw materials in a multilayer structure

• The substrate can be tailored for each device by modifying surface energy, surface roughness and surface porosity through choice of raw materials and surface treatment methods

• Adequate barrier properties and sufficient printability can be combined • For large scale manufacturing curtain coating can be used

The silver ink is sintered online using IR radiationLow surface energy

Low absorption

High surface energy

Low absorption

High surface energy

High absorption

Conclusions

Ring‐oscillator (Schematic setup)

PaperCon 2011 Page 2942