MSE 542Flexible Electronics

Lecture 1

Tuesdays, 1:25 pm to 4:30 pm

Olin 245

Example 1:Flexible Displays

• Flexibility enables new concepts in electronics

Smart Biomedical Bandages

Temperature Sensors

AntennaControl Electronics

and RFID

Battery

Fluid SensorsGas Sensors

Example 2:Smart Bandage

Simple processes enable low cost

What is Flexible Electronics?

• Flexible electronics “can be bent, flexed, conformed or rolled to a radius of curvature of a few centimeters without losing functionality”

• Thin profile

• Large area

• Conformal

• Flexible

• Wearable?

• Possibly manufactured roll-to-roll

Course Description• Flexible electronics holds the promise of transformative

developments in: (1) flat panel lighting (low cost, low energy), (2) energy production systems (solar) and (3) infrastructure control and monitoring (sensing, energy control, hazard monitoring).

• Practical realization of flexible circuits will require dramatic progress in new materials that are compatible with flexible media and amenable to facile and low temperature processing as well as major advances in manufacturing technologies such as roll-to-roll processing.

• This course will discuss these and other developments.

• Lecturers will come from Cornell, GE, IBM, EIT, Binghamton

Technology Convergence Makes Flex Possible

• Thin film transistors

• Active matrix

• Conducting layers

• Plastic, glass and metal substrates

• Barrier layers

• New deposition methods

Why is This Topic so Exciting?

• Flexible electronics, if low cost enough, means that we can give electronic attributes to everyday objects

• Imagine displays that roll up and fit in your pocket

• Imagine solar panels are your clothes or the fabric is a sensor net

• Imagine light sources you hang like a picture on a wall

Examples

• Flexible Displays

• Flat Panel Lighting

• Solar Cells

• RFID Tags

• Smart Bandage

Pioneer e-Ink & Lucent Electrolux

Electronics go everywhere

Sony eReader

RFID

• Imagine a carton of milk with RFID tag

• Refrigerator will tell you when it is out of date or used up

• Will be used to track inventory of most retail items

• Where will it end up?

Alien Technology

Pioneer(2001 - demo)Pioneer

(1997)

Motorola(2001)

Kodak(2004)

Sony(2004)

Organic light emitting diodes (OLEDs)

OLEDs vs. Liquid Crystals

GE

OLEDs for lighting

Electrolux

All-polymer integrated circuits (Philips, 1998).

Organic thin film transistors (OTFTs)

SustainableTechnologiesInternational

Solaronix

OPVs Solar Cells for energy production

Class Expectations• There will be problem sets

approximately every two weeks.

• There will be a class prelim.

• There is NO FINAL, but there is a term paper due during study week. – The topic will be selected in conjunction

with the course instructor.

• 30% Homework

• 30% Prelim

• 40% Final Term Paper

Seminar Series

• We will hold a separate seminar series starting mid-way through the semester

• Distinguished speakers are leaders of the developing flexible electronics community coming from industry and academia

• Attendance at seminars will be greatly encouraged, but is optional

Texts• Flexible Flat Panel Displays (Wiley Series in

Display Technology) (Hardcover)– by Gregory Crawford (Editor) – Hardcover: 556 pages– Publisher: John Wiley & Sons (June 21, 2005) – ISBN: 0470870486

• Principles of Electronic Packaging – by Donald Seraphim, et al.– Hardcover: 962 pages– Publisher: McGraw-Hill College (March 1, 1989)– ISBN: 0070563063

Silicon Run Video

• This video shows where flexible electronics comes from, factors to consider

• It is important to see what flexible electronics is evolving from and to understand that today these are not yet competitive areas

• Not as small, not as fast, but enabling new uses and concepts to be realized

Break & Discussion• What did video show?

• Showed chip processing - now we need to consider “packaging”

• Adjustments to get higher performance

• Used to be considered less important, but now package is bottleneck in many electronics if not done right

• Advances in packaging are basis of new flexible electronics!

Other Ideas?

• environmental sensors

• make inanimate devices active - e.g. furniture, rooms, etc.

• tag everything - passports

• biomedical implants - connect the nervous system to the external world

What skills do we need?

• Flexible electronics can be thought of as combination of microelectronics (albeit on larger scale) with electronic packaging

• Need understanding of materials and electronics

• It is a new and developing area

• As such we will look at this from perspective of both these areas

• Most of all we need imagination!

What makes flexible different from current microelectronics?

• Thin form enables flexibility, BUT places additional demands on mechanical performance

• Normal protective packaging is too big, so new methods of protection are needed

• Speed is not essential

• New methods of manufacture may enable cost reduction, but compromise robustness

Course InstructorsProf. C. K. Ober, Cornell lead

• Dr. Poliks, EI lead

• Prof. Baker

• Prof. Giannelis

• Prof. Malliaras

• Prof. Thompson

• Prof. Sammakia, BU

• Dr. Obrzut, NIST

Dr. Calmidi, EI

Dr. Chan, EI

Dr. Egitto, EI

Dr. Fillion, GE

Dr. Korman, GE

Dr. Magnuson, EI

Dr. Matienzo, EI

Dr. Wilcox, IBM

" Over 40 Years experience in development and fabrication of leading edge technology

" Incorporated as Endicott Interconnect in November 2002

" A tradition of technical invention

" Facility - 1.3M sq feet manufacturing and lab space

" EmploymentFabricationEngineeringResearch & Development

" Prototyping through volume production in three shift operation

EI Corporate Profile

Class Outline

Jan. 24 Course overview: What is Flexible Electronics? (Ober)

Jan. 31 Design: Connectors and interconnects (Chan, EI; Wilcox, IBM)

Feb. 7 Technology Focus: Displays and lighting (OLEDs) (Malliaras)

Feb. 14 Performance: Electrical performance and characteristics (Obrzut, NIST)

Class OutlineFeb. 21 Design: Single and multichip packages

(Fillion, GE)

Feb. 28 Processing: Lithography and pattering (Ober)

March 7 Processing: Laser processing and via formation (Egitto, EI)

March 14 Design: Substrates and barriers (Poliks, EI; Giannelis)

March 28 The Flexics Story - History of a Startup (Thompson; Wickboldt, USDC)

Class OutlineApril 4 Technology Focus: Solar energy

conversion (Korman, GE)

April 11 Processing: Metal deposition (Baker; Magnuson, EI)

April 18 Performance: Physical Analysis (Matienzo, EI)

April 25 Design: Future technologies (Chan and Lin, EI)

May 2 Design: Thermal management and reliability; Course Wrap-up (Calmidi, EI; Sammakia, BU; Ober)

Or What Do Electronic Devices Need To Do?

• Chip/Circuit Protection

– Environmental, thermal, mechanical

• Communication

– Maximize I/O

• Power• Heat removal

- Forced or natural convection

- Wiring structure and power interconnects

What Is Packaging?

• Rivals microelectronics in terms of industry size and complexity

• Critical bottleneck in device speed

• Sets size and capability of electronic device

• Determines cost of device

Packaging vs. Microelectronics

The Package

Each level needs to meet goals of package!

• 1st Level – chip on substrate

• 2nd Level – card

• 3rd Level – card on board

– packaging getting as sophisticated as microcircuit

– how will we categorize package for flex?

Levels of Packaging

Packaging Technologies

New Technologies Needed for Flex

• Materials selection

• Circuits on substrate

• Processing conditions and limits

Conductors

Fewer conductors to choose from

Insulators

Largely organics

2nd-Level Packages(How would they function for flex?)

Single Chip Packages

• Die attach

• Wire bonding & Plating

• Encapsulation - molding compound

• Package types

• Quad flat pack

• PLCC

• PGA

• BGA

• C4

Chip Package

• Combine several chips in one package

• Reduces signal delay time

• Heat dissipation

• Stress relief

• Substrate is high signal density layer

TypesMCM-LMCM-CTCM

Multichip Modules

• Attach chip to plastic carrier with metallization

• Looks like 35 mm film

• Speeds up production

• Usually polyimide & copper

• Flex circuits use similar technology

Tape Automated Bonding (TAB)

• Composite - often epoxy/glass

• Parallel process

• Screen printing

• Lamination

• Multilayer crossed by vias

• Capacitance, inductance and resistance

• Pick and place

• Solder & reflow

• Thermal issues

PCB or PWB

• Maximize I/O

• Minimize thermal issues

• Heat dissipation

• Thermal stress

• Environmental protection and encapsulation

• Lowest cost needed to get results

• Drive to continuously reduce size and power

Common Themes(Flex will have to achieve this)

Endicott

Interconnect

Microelectronics Advanced Interconnections

Laser via / thin film / z-interconnect based interconnect technology needed to reduce the IC to PWB interconnect gap

HyperBGA is a registered trademark of Endicott Interconnect Technologies, Inc.

Semiconductors versus PackageSmallest features: “parallel paths” for how long?

IC scaling

Time

PWB

PWB w/ buildup layers& Laser vias

Reduced Interconnect

Gap

HyperBGA® Interconnect technology

2000’s1990’s 2010’s

Z-interconnect technology

Meso

Micro

Nano

InterconnectGap

$SOP

Source: adapted after

Shipley

© 2005 Endicott Interconnect Technologies, Inc.

Endicott

Interconnect

Time 2015-202000-5

2005-10 2010-15

Func

tion

-- D

ensi

ty

Data Rate Gb s-15 20 10 40

Embedded Actives

Electrical Interconnect

Optical Interconnect

Embedded Passives

Integrated Systems Technology Evolution

Organic z-interconnect

IntegratedFlex, Optical, Passives & Actives

Enhanced Thermal and Power Management

IntegratedOptical, Passives

HyperBGA

Integrated RF

Flexible Substrates

© 2005 Endicott Interconnect Technologies, Inc.

• Flexible substrates

• Barrier layers

• Inorganic conducting layers and mechanical properties

• Organic conducting layers and mechanical properties

• Optical coatings

• Thin film transistors

• Electro-optic materials

Flexible Electronics:Enabling Materials

• Patterning Methods

• Printed organic electronics

• Rollable materials

• All plastic systems

Enabling Processes

• Flexibility creates potential problems as the multilayer film is flexed

• Different E

• Different CTE

Flexibility

Stress Cracking

Modulus mismatch leads to stress cracking

Mechanical Properties of Layer Components

MaterialYoung’s modulus,

E (GPa)

Coefficient of Thermal

Expansion, CTE (ppm/K)

Hardcoat 6.0 ± 0.5 61 ± 1

Base polymer 2.9 ~65

Gas Barrier 150 10

ITO 119 ± 5 7.6

Organic Substrates

Flexible plastics are not as thermally stable as glass or metal

New Semiconductors

Polymers can be used a semiconductors and even doped to be conductors

TFT’s

• TFT’s on flexible substrates can be produced from polymeric or inorganic semiconductors using printing methods

• Barrier layers are needed to protect the various components from the environment

Barrier Layers

• New processing is enabled by new materials

New Patterning Methods

Future Prospects

• Future applications not even imagined do not appear here

The U.S. Early Adopter for Flexible Displays

The Air Force has announced a complementary program using OLED on SSSource: John Pellegrino (ARL) and Darrel Hopper (AFRL)

UNIVERSITIES

GOVERNMENTLABS/RDECs

INDUSTRY

Technology into Center

Technology subsetsfrom the Center (i.e. backplanes)

Limited Quantitiesof

Display Demos

Flexible Display Center @ ASU

United States Army

Flexible Display Centerof Excellence

Roll-to-Roll Manufacturing R&DMotivation and Purpose

A proposed means to lower the cost of producing flexible displays in a high-volume manufacturing

environment by taking advantage of a unique attribute of flexible substrates relative to the traditional thick

glass substrate used in LC displays.

Such a manufacturing paradigm, compared to the traditional batch process (cluster tools and cassette transport), generally does not enable any enhanced

product performance characteristics.

What is Roll-to-Roll (R2R)?

• Substrate is a Flexible format

• L>>W>>T

• Can be stored in coils (D<1m)

• Handled in Rolls:

Unwind – process - Windup

T

W

L

SteelPlastics

D“Web”

Converging interests from other developing industries

Opportunity: pool resources and knowledge

Large Area

Solid State Lighting• Low cost production of OLED

panels

Thin Film Photovoltaics•Reduce cost

•Improve yield

Flex Circuit Packaging•Reduce L/S < 15um

•Embedded actives, passives

•Integrated passives, active

Low Cost RFID•New TFT technologies

High precision R2R electronics

manufacturing

Challenges & Opportunities for R2R• Engineering

– Need to develop R2R equipment to operate at IC-industry specifications

Existing hurdles:

– Damage due to handling

– Particle generation

– Impurity due to contact

– Yield management

– Linear processing

• Financial

– A fully integrated facility

– Lower capital cost

– Lower labor costs

Because it may be essential to enable the high volume applications of flexible electronic products and systems and it is highly compatible with organic electronics & solution processing!

• Flexible

• Formable

• Weight

• Ruggedness

• Low Cost

• Many customers will not pay a premium for these.

• However, a premium is inevitable for new

technology.

• Customers have come to expect lower cost!

Roll-to-Roll Production?

Why R2R Manufacturing?

Roll-to-Roll ManufacturingWhat it is NOT in the context of the FDI!

• Not an essential capability to produce flexible displays

• Does not satisfy a gating Army need (volume, application variability)

• Not a near term capability (either from an ability to accomplish or a market demand point of view)

• Does not meet the Army timeline

• Not appropriate for a display technology development environment

USDC CONCLUSIONS & GUIDANCERoll-2-Roll Manufacturing – A Companion Initiative

• Supporting Factors– There is insufficient funding in the Army program to do both initiatives ►spend the “marginal” funding on the important and essential display component deliverables at the FDC

– Keep the ASU team focused on displays and backplanes to meet the Army’s objectives for the FDC

– Core competencies very different for addressing flexible displays and R-2-R manufacturing technology ►different industries [tool & process development expertise] and very different academic R&D expertise

– Commission someone else with the responsibility to secure additional funding and support• Other funding avenues, e.g., state, federal, industry

• Industry partners from outside the display community

– Efforts can run more concurrently [although not essential to meeting Army flexible display objectives] without dissipating focus and funding

New effort in U.S.: CAMM (Center for Advanced Microelectronics Manufacturing)

• Located at Binghamton University (New York State)

• Launched in January 2005• Develop and demonstrate

advanced integrated R2R manufacture of microelectronics

• Test site for USDC R2R projects• Facilities provided by Endicott

Interconnect TechnologiesSigning Ceremony Jan’05

If there is interest, we can visit!!