© PEL 2010 IeMRC 21 Sept 2010 PEL is focussed on the development, characterisation and manufacture of electronic circuits and devices using materials and functional inks deployed by inkjet and direct writing.

Steve Jones Steve.jones@printedelectronics.co.uk

www.printedelectronics.com

Digital Printing of Electronics Putting electronics in new places

PEL is focussed on the development, characterisation and manufacture of electronic circuits and devices using materials and functional inks deployed by inkjet and direct writing

What is Electronics?

• Electronics is about interconnecting components to form a functional device

– Display, internal power, input and out,

– And it does something…makes phone calls, controls the washing machine, plays a musical doorbell, etc

• Electronics is so ubiquitous it has become invisible

• We don’t tend to talk about electronics; we talk about the application and its functionality

• An electronic design is based on a library of component data; many suppliers and millions of man years of data on function and reliability

• Electronics has form, function and purpose, and is fit for the purpose for which it was designed ie it’s reliable and durable

© PEL 2010 IeMRC 21 Sept 2010

What is Printed Electronics?

• Circuitry created with conductive and/or electro-active inks using a

wide variety of printing techniques ie the inks are the components

usually in the form of nano-particles in a carrier that gives an

appropriate surface tension and viscosity for the printing method.

• We presently do not have a library of component data; few suppliers and little data on function and reliability

• However, printed electronics must form, function and purpose, and is fit for the purpose for which it was designed ie it’s reliable and durable

© PEL 2010 IeMRC 21 Sept 2010

Printed Electronics Limited (PEL)

• PEL is a process development company

– Using in house facilities for proof of concept through to pre-production level.

– Develop/specify systems, processes and material sets for use in end-customer operation at production level.

• Mainly developing inkjet-electronics and material deposition by inkjet techniques:

– Circuit printing, dielectric application, display printing

• Management of PEL have long experience in PCB manufacturing and semiconductor development.

• Offices in Cambridge and Tamworth, UK

– Team of industry specialists.

• Developing processes for a number of clients

IeMRC 21 Sept 2010 © PEL 2010

Print techniques

SCREEN INKJET

© PEL 2010 IeMRC 21 Sept 2010

PEL & Inkjet electronics

What is inkjet electronics? • A wide area of global activity

– Displays – OLED / LCD filters etc

– Semiconducting materials

• Memory

• Flexible transistor structures

• PEL is primarily focussed on

– Developing interconnected structures by inkjet methods

• Essential for the development of functional inkjet electronics

– Novel manufacturing techniques for new materials

• Developing a toolkit for Printed electronics

© PEL 2010 IeMRC 21 Sept 2010

Why inkjet electronics?

© PEL 2010 IeMRC 21 Sept 2010

IeMRC 21 Sept 2010

Why … ?

(Inkjet is not always the best method for printing of electronics…

e.g. we also CHOOSE to use screen print and nozzle dispensing)

• Inkjet is truly additive

• No hard tooling

• Non-contact

• In an inkjet electronic world (and in plastic electronics generally) electronics don’t have to be flat and neither do they have to be flexible

– Designers love flexible electronics

• Printed (including inkjet) electronics doesn’t have to look like conventional electronics eg combine with graphics

– It can be curved, low cost, can be disposable with low environmental burden.

– It can be used on packaging, advertising, clothing etc

© PEL 2010

IeMRC 21 Sept 2010

The Advantages of Inkjet

Electronics

…or “the new things that can be done”

© PEL 2010

IeMRC 21 Sept 2010

Multilayer PCB entirely by inkjet

7 layer structure:

1. Silver (base)

2. Dielectric 1

3. Silver

4. Dielectric 2

5. Silver

6. Dielectric 3

7. Silver

Note – vias are not

necessarily round

Status – State of the art (proof of concept) © PEL 2010

IeMRC 21 Sept 2010

Very long circuits (single layer on PET )

• Reel-to-reel continuous printing – potentially 2km in single print

• Digital image can be changed dynamically

• Cannot be done by conventional panel processing methods

• Application – printed sensors etc

• Status – available now from CIT. Plated Cu on PET. – CIT process is predominant method for reel to reel inkjet electronics (www.inkjetflex.com)

© PEL 2010

Circuits on wearable fabric

Circuits in clothing:

Check www.CuteCircuit.com

• Application

– Fashion, communications etc

• Status

– in development at PEL and

elsewhere

© PEL 2010 IeMRC 21 Sept 2010

Inkjet’s high precision drop placement

(i) Security application

• Precise drop volume;

each droplet can be

placed with a precision of

~m to each other

• Functional materials

• Pharmaceutical or

tracer/marker materials

• Application – identity

protection, covert and

overt security.

• Status – available now

(PEL).

Machine-readable “single pixel” 2D barcode.

Hidden Marking application

© PEL 2010 IeMRC 21 Sept 2010

Inkjet’s high precision drop placement

(ii) transistor interconnect

IeMRC 21 Sept 2010

Printed Ag lines are 35um in width

Printed drop size is 1pl

Ag Ink and transparent insulator

With kind permission of Nanoeprint

Status – proof of concept

(pre-production capable)

© PEL 2010

Benefits of non contact printing

- Printing into recesses

• Application

– Printing where conventional contact print methods cannot be used

• Status

– Available for compatible structures only

© PEL 2010 IeMRC 21 Sept 2010

Highly curved surfaces Aerospace Helmet

PEL have developed this

system as a proof of

concept for doubly curved

surfaces.

System builders (such as

Xennia) have commercial

systems with multi axis

robots to control 3D printing.

PEL System

© PEL 2010 IeMRC 21 Sept 2010

Applicable methods for packaging

© PEL 2010 IeMRC 21 Sept 2010

Direct Conductive Print (DCP) on paper, plastics and ceramics

e.g.

• Developed a process to achieve conductivity on low cost paper based substrates etc without high temperature cure.

• Circuit structures manufactured in < 1 minute

• Cure in seconds (heat or photonic)

• Application – Non contact printing of circuitry

• Status – Process available for prototype

and pre-production level.

© PEL 2010 IeMRC 21 Sept 2010

© PEL 2010

Printing in CMY

• PEL Array head designed to allow

simultaneous printing of different

inks.

Applications

• Graphics and electronics – print colour graphics to hide electronic

circuits or other features

• Print chemically reactive species

to form chemical reactions on a

substrate

• Biological: simultaneously print a

range of biologically active

material – can change the printed area and

concentration of functional materials

Status – proto-production

• Metals:

– Au

– Ni

– Ag

– Cu

– Si

On PEL-paper substrate, nano metal inks

will functionalise to become conductive

with 120°C fast cure or pulsed xenon flash

K Ag Cu Au K

IeMRC 21 Sept 2010

Printed Displays (EL)

• Direct print onto substrate (ie paper, plastic etc)

With the “right” substrate - very high definition images can be produced .

Pixel size ~60µm on “PEL coated

paper”

• Application –

marketing/branding

• Status – available with inkjet

and screen print methods.

© PEL 2010 IeMRC 21 Sept 2010

Graphics + Electronics

• Combination of colour graphic

printing with circuit designs.

– Packaging

– Branding

– “attractors” for trade shows etc

• Application

– Branding graphics

– Overprinting - printed onto

assembled components

• Status

– Available

© PEL 2010 IeMRC 21 Sept 2010

So it can be done….

How do we do it?

© PEL 2010 IeMRC 21 Sept 2010

Inkjet Electronics

• The fundamentals of inkjet printing

of interconnects involves 4 basic

elements or processes.

– Head

– Ink

– Substrate

– Functionalisation

and, of course, a Print Platform

ink

head

substrate

© PEL 2010 IeMRC 21 Sept 2010

Ink jet HEAD

• Successful functional inkjet is entirely about the “1mm journey”

– From Nozzle to Substrate

• Correct drop formation is critical - controlled by a “waveform”

• The drop characteristics when it hits the substrate are a complex function of many parameters

“The 1mm Journey”

Substrate

~1m

m

© PEL 2010 IeMRC 21 Sept 2010

Inside an inkjet head (Xaar1001)

Toolkit item: YES

© PEL 2010 IeMRC 21 Sept 2010

#1 Consideration

Whatever ink one chooses to print must be

compatible with the head and give long term

reliability.

© PEL 2010 IeMRC 21 Sept 2010

Inks for electronics applications

© PEL 2010 IeMRC 21 Sept 2010

What's in an ink?

A dispersion or solution of

Functional material

Solvent(s)

Dispersant

Others

Binder(s)

Surfactant or wetting agent(s)

Humectant

Rheology modifier

...and more

.

© PEL 2010 IeMRC 21 Sept 2010

Ideal Characteristics for an inkjet ink

Surface tension 20 to 30 Dynes/cm

Viscosity range 8 to 12 cps

© PEL 2010 IeMRC 21 Sept 2010

What is in a typical nano-metal ink?

• It is a liquid mixture of:

– what I want to keep

• i.e. Ag, Cu, Au, Ni particles

– what I must get rid of

• i.e. organic solvents,

stabilisers, viscosity

additives.

– Generally the list of “what I

want to keep” is shorter…

• A 40% by weight silver ink

is 4% by volume; therefore

96% of the ink volume has

to “disappear”. Solvents can

disappear but dispersion

agents tend to hang around.

© PEL 2010 IeMRC 21 Sept 2010

Conductive inks

– Available inks and example suppliers

– Cu, Ni (Intrinsiq), Ag (Sunjet, ANP), Au etc

1 H

2 He

3 Li

4 Be

5 B

6 C

7 N

8 O

9 F

10 Ne

11 Na

12 Mg

13 Al

14 Si

15 P

16 S

17 Cl

18 Ar

19 K

20 Ca

21 Sc

22 Ti

23 V

24 Cr

25 Mn

26 Fe

27 Co

28 Ni

29 Cu

30 Zn

31 Ga

32 Ge

33 As

34 Se

35 Br

36 Kr

37 Rb

38 Sr

39 Y

40 Zr

41 Nb

42 Mo

43 Tc

44 Ru

45 Rh

46 Pd

47 Ag

48 Cd

49 In

50 Sn

51 Sb

52 Te

53 I

54 Xe

55 Cs

56 Ba

* 71 Lu

72 Hf

73 Ta

74 W

75 Re

76 Os

77 Ir

78 Pt

79 Au

80 Hg

81 Tl

82 Pb

83 Bi

84 Po

85 At

86 Rn

Toolkit item: YES

© PEL 2010 IeMRC 21 Sept 2010

Dielectric Inks

• Printable dielectrics

– Acrylic systems

– Epoxy systems

– Polyimide

– SU-8 (Popular in inkjet

applications)

• Choice of dielectric is highly

dependent on substrate and

conductive ink combinations .

Toolkit item: YES

© PEL 2010 IeMRC 21 Sept 2010

Platform

• Dimatix DMP 2800

• Dimatix DMP 3000

• Microcraft

• DGI/Dilli (Korea)

• iTi

• Samsung

• PixDro

• CeraDrop etc

• Costs vary from £30k to

£250k for a basic system.

• Decision is very

dependent on the inkjet

head and market that will

be your main focus.

Toolkit item: YES

© PEL 2010 IeMRC 21 Sept 2010

Substrates for electronic

applications

© PEL 2010 IeMRC 21 Sept 2010

Common substrates for Printed Electronics

• Polyimide – High temperature resistance widely used in electronics

• FR4 – Epoxy resin reinforced with woven e-glass

• Cu – Electroplated foil

– Brushed surface

– etc

• Glass and Plastics – Display applications

For packaging applications

• Paper

• Plastic (PET, PEN etc)

© PEL 2010 IeMRC 21 Sept 2010

Comparison of drop sizes in flight and on substrate

• Drop volume V, Drop radius r

• Drop on surface

– Rule of thumb:

• 2 ~ 4 times diameter in flight

3

3

4rV

8pl ~ 24um

8pl ~ 50~60um

© PEL 2010 IeMRC 21 Sept 2010

IeMRC 21 Sept 2010

Interactions of Nano Ag on Paper

With thanks to Cambridge University IfM

A PEL Partner

IeMRC 21 Sept 2010

It’s PAPER Jim, but not as we know it

Ag

Coated Paper

• One can use “photo-

paper-like” substrates

for conductor printing.

– Not all photo-paper

works well.

• Surface structure is

critical to the

performance.

• Specialist paper is

required.

Toolkit item: YES

© PEL 2010

Next process steps

• Sintering of the printed metallic layers

– Sintering: Bonding of adjacent surfaces of particles by heating

– To make the layer conduct

• Curing dielectric materials

– By UV exposure etc

• Drying layers

– Thermal/Xe

All of which is termed “Functionalisation”

ink substrate

© PEL 2010 IeMRC 21 Sept 2010

Functionalisation

• Method employed is dependent on

the material being deposited

– Nano metal ink ALWAYS require

sintering

• With the right substrate and ink the

sintering temperature can be

120~140°C

• High energy UV flash is very effective

– UV curing materials (i.e. dielectric):

• Decide on UV pin or UV cure

• Very different behaviour can be

generated

– Especially important for multilayer

structures.

www.nanomastech.com

PEL UV Cured 3D structures

© PEL 2010 IeMRC 21 Sept 2010

NanoAg Functionalisation

• Paper based substrate

• Flash heated to 140C for

a few seconds

• Pulsed Xe flash 1ms

• Forms a continuous layer

of Ag with low resistance

– 16% and up of bulk silver

value

Ag

Paper substrate

Time (60s)

© PEL 2010 IeMRC 21 Sept 2010

Pieces of the puzzle

SUB- STRATE

INTERCONNECT Ink

Process Functionalise Interconnect

Function

Conductive Epoxies etc

FULL PRODUCT Conventional Components

• Successful printed

electronic demonstrators

rely (for the foreseeable

future ) upon conventional

electronic components

too.

• Combining successfully

the required elements is

the key to functional,

reliable products.

IeMRC 21 Sept 2010 © PEL 2010

Industrial Process Development

Key Considerations

• Cost benefit • Fixed cost and variable cost elements

• Robustness of process – Variation in materials

• One supplier for (eg) substrate + ink – early stage ok

– Later maybe not

• Is the scale suitable for inkjet?

– Materials developers point of view • Have you considered the requirements for “electronic” applications

• Nanomaterials – particle size / batch release

© PEL 2010 IeMRC 21 Sept 2010

Cost considerations

• Is inkjet the right solution for your application? – What must the process

provide?

– Is it better or “just different”

– Financially – is the process sound

– >> cost calculator for single layer nano Ag circuits

Cost Elements

Image size (mm) 80 80

DPI 309

% of image that is black 20%

Number of passes 3

HEAD - Drop volume (pl) 50

INK - Cost per litre (£) 3500

Number of dots in X 973

Number of dots in Y 973

Number of dots (using % of black) 568,304

Volume of ink used (ml) 0.0284

Cost of circuit (£) £0.10

© PEL 2010 IeMRC 21 Sept 2010

Conclusion

• Inkjet has no tooling, it is a fully additive digital process.

– Offers products and processes that are impossible by any other

means

– Start-up costs are low.

• Inkjet printing can deliver a very precise amount of

material to a specific location on almost any material

(e.g. for electronic or pharmaceutical applications)

• Printed electronics can add value to packaging.

© PEL 2010 IeMRC 21 Sept 2010

Additional Support

Project Sector Partners Status

COPE (TSB) Aerospace BAE Systems,

Oxley, Sun

Active

FAB3D (TSB) Displays Johnson

Matthey, Brunel

Active

Interactive Audio (TSB 1 yr) Advertising/Cons

umer

Novalia, IWT Active

SportSensorSuit (TSB 1 yr) Sport science CuteCircuit,

Frazer

Active

Clip (FP7) Printed

electronics

Pera, Intrinsiq Active

© PEL 2010 IeMRC 21 Sept 2010

Thank You

© PEL 2010 IeMRC 21 Sept 2010

IeMRC 21 Sept 2010

Blatant Advert… PEL “InkTronics” courses

Inkjet Electronics 101 • Basic ink rheology of electronically functional/nanoparticulate inkjet

inks

• Introduction to binary and greyscale technology inkjet heads

• Drop visualisation and satellite formation

• Ink drop/substrate interaction and spread characteristics

• Substrate surface modification

• Printing and functionalisation of electronically functional inks using Dimatix DMP and Xaar equipped iTi printing systems. The course is practically based and the participants will use our drop visualisation, surface energy modification equipment and inkjet machines to print and functionalise simple circuits.

Contact us info@printedelectronics.com

© PEL 2010