cleaning techniques for oled and opv of delft summer...r2r compatible cleaning techniques technique...

Cleaning Techniques for

OLED and OPV

Adding Value by Reducing

Defects

TU Delft Summer School 13/5/2019

Outline

• Introduction

• Clean4Yield

• Cleaning Technologies

• The Theory of Small Particle Adhesion

• Empirical Evaluation

• The Cleaning Outcomes

• New Applications

• Summary3/5/2019 TU Delft Summer School 2

INTRODUCTION - TEKNEK

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Who are we?

• Company formed 1984

• Acquired by ITW (Illinois Tool Works) in July 2011.

- $18billion sales

• Inventors & world leaders in the manufacture & design of roller

contact cleaning systems

• Global footprint

• Distribution world-wide

• Over 20,000 machines manufactured and delivered to diverse range

of industries

• Produces its own cleaning rollers & adhesives

– 10,000 cleaning rollers per year

– Design and Produce in UK, adhesive centres in UK, USA & UK

– Use around 1.2 million sq. metres of adhesive product per year

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Primary Converting

Secondary Converting

FPD and BLU Assembly

Cleaning Applications

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CLEAN4YIELD PROJECT

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Clean4Yield

• Clean4Yield is a collaborative EU funded project which is tackling

one of the most pressing issues in organic electronics – ensuring

high enough yields for cost-effective manufacturing.

• Objectives

• The objective of the Clean4Yield research project is the

development and demonstration of a holistic concept for the

detection/inspection, cleaning, prevention, and repair of defects and

contaminations in nano-scale layers applied in OLED and OPV as

well as high end moisture barrier films, which are deposited on

flexible substrates by R2R (roll-to-roll) coating and printing

techniques. This will lead to increased yield, better performance,

longer operational device lifetimes and reduced production costs.

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Clean4Yield WP3 Objectives

• Removal of particles down to 100nm

• No damage to substrate or underlying layers

• No unwanted change in surface energy

• No cross contamination

• In atmospheric coating and vacuum deposition

• Substrates of PET and PEN foils, glass and

coated substrates

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CLEANING TECHNOLOGIES

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Technology Drivers

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• Films are getting thinner – easier to damage by

particles in the wind of the roll

• Coatings are getting thinner – even nanoscale

particles can cause pinholes

• The functional requirements on coatings are

becoming more demanding

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Issues

• Particles of contamination on substrates cause

defects in processes used in Flat Panel Display

manufacturing and Organic and Flexible

Electronics

• Defects cause significant yield loss

• Removal of particles is essential for high

functionality and reliability

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R2R compatible cleaning techniquesTechnique

Particle removal efficiency indication / %Remark

0.1 - 1 1 - 10 10 - 40 > 40 µm

Contact cleaning

Rotary wet wipe ? > 90 > 90 > 90 risk of damage of soft layers and cross

contamination

Rotary brush + vacuum 0 0 > 50 > 90 risk of damage of soft layers and cross

contamination

Tacky rollers

metal particles

organic particles

50 - 90

?

> 90

< 50

> 90

50 - 90

> 90

> 90

depending strongly on substrate and

particle material and humidity

Non contact – traditional

Air knife 0 0 < 50 > 50 no small particles

Air + ultrasound 0 0 > 50 > 90 no small particles

High velocity + vacuum 0 < 10 < 50 > 90 no small particles

Non contact – new

narrow gap (liquid or gas) ? ? ? ?new technology

only for rigid substrates so far

high velocity nano spray > 50 > 90 > 90 > 90 only DI water needed, no damage

CO2 snow ? > 50 > 90 > 90high gas consumption, cooling down of

substrates

Plasma

Plasma

(only organic particles)> 10 < 10 < 10 < 10

only organic thin film contaminants and

small particles

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100 75 50 30 25 10 5 1 0.5 0.2

Air Knife

Brush & Vac

High Velocity Vacuum

Ultrasonic

Contact Clean Machine

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Particle Size, Microns

Efficiency of Cleaning Methods

Comparison of cleaning efficiency's

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Contact Cleaning Technology

The Teknek Cleaning Core

PPT 7 / 21

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THE THEORY

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Basic Theory

• Adhesion force applied by elastomer to particle

must be greater than the force holding the

particle onto the substrate

• Force exerted on the particle by the adhesive

must be greater than the adhesion force of the

elastomer

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17

Cleaning Scenario

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Adhesion Forces

• Adhesion describes how a particle and a surface

are held together

• A number of different forces will act together to

produce the adhesion force combination

• Two bodies in contact, an attractive force occurs

that requires a mechanical load to separate

them

• Strength of adhesion is determined by how

strong the interactions are

Adhesion forces

• At least 15 types of adhesion force, including 38

variables

• Analysis done on the force equations and

variables

• Two key variables identified, namely particle size

and contact area

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Conceptual Model

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Contact Area

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EMPIRICAL EVALUATION

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Initial Research

• Focus on measuring adhesion forces

• Using AFM

• Particle size 10micron

• Particle types – Silica, gold and

polystyrene latex

• Substrates – Elastomers and standard

films

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Shore Hardness vs PPU

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Elastomer properties

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Substrate Adhesion

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Particle measurement

‘PMC’ tool - a method using adhesive cards from forensic technologies

(developed with TNO-D) used to measure surface contamination (> 2mu)

levels

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Cleaning Efficiency

0

100

200

300

400

500

600

700

800

0 1 2 3 4

Par

ticl

es/c

m2

Number of cleaning strokes

Particle removal with manual Nanocleen roller from PET foil

Copper 3-10 micron Copper 3-10 micron

PSL 10 micron PSL 10 micron

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Other Collaborations

• The Holst Institute

• The Fraunhofer Institute

• Technical University Dresden

• Technical University Delft

• Korean Institute of Machinery and Materials3/5/2019 TU Delft Summer School 29

CONTACT CLEANING

OUTCOMES

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Silicone Free Cleaning Engine

• Silicone free cleaning rollers

• Silicone free adhesive

• Silicone free confirmed by – FTIR,

– Edx (Energy-dispersive X-ray spectroscopy)

– RGA (residual gas analysis)

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Nanocleen RGA

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Static Dissipating Elastomer

• Nanocleen

– Static dissipating NO conductive particles – clever

polymers not cheap additives

– Dyne Neutral, contact angle (Measurements on PET)

• Uncleaned contact angle 71.57, SD +/- 1.49

• Cleaned with Nanocleen 71.80, SD +/- I.46

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Static Trials - Japan

Traditional

Rollers

Static

1000 volts

Nanocleen™

Static

100 volts

Static Bars – switched OFF

Traditional

Rollers

Static

100 volts

Nanocleen™

Static

10 volts

Static Bars – switched ON

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