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FLEXIBLE ELECTRONICS
PHYSICAL METHODS IN MATERIALS CHARACTERIZATION
L.J. MATIENZO, Ph.D.
FLEXIBLE ELECTRONICS Combining Materials into Electronic Packages (1990s)
Wire Bond
30K Circuits (CMOS)250 I/O (Chip)
0.006 inch WB Pad Pitch
Flip Chip
200 - 300 I/O (Chip)0.010 inch C4 Pitch
0.5 - 0.65mm TQFP<100 I/O
Memory TSOP30 - 40 I/O
Wire Bond300 - 500 I/O (Chip)
0.004 inch WB Pad Pitch
0.25 - 0.3mm TQFP300 - 500 I/O (Chip)
Flip Chip1000 I/O (Chip)
0.009 inch C4 Pitch
MCM's (3x3)1300 I/O (Module) Integrated Flex
Connector
Source: IBM Corp., with permission and L. Tiemann, IBM Corp.
Chip
Chip Carrier
Encapsulant
Wire
Wirebond Assembly
(a)
(b)
Chip
Chip Carrier
Underfill
Conductive Joint
Flip Chip Assembly
FLEXIBLE ELECTRONICS Dielectric Polymeric Films as Protective Device Layers
Chip
Chip Carrier
Encapsulant
Wire
Wirebond Assembly
(a)
(b)
Chip
Chip Carrier
Underfill
Conductive Joint
Flip Chip Assembly
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)
Thermal Ball Grid Array (TBGA):
Light weight and flexible packagesIncreased number of I/OsExtensive use of polymeric dielectric layerMetallized areas are used to create conductors
Hyper-Ball Grid Array (Hyper-BGA):
Required for processors with increased speeds (GHz)I/O numbers in the thousandsDielectric constant of polymeric material is criticalMechanical and electrical performance is required
FLEXIBLE ELECTRONICSBall Grid Array Technologies
FLEXIBLE ELECTRONICSEarly Flexible Circuits (ca. 1990)
Flexible circuit
Flexible circuit
Source: L.J. Matienzo and F.D. Egitto Solid State Technol. 38, 99 (1995)
*Values supplied by Joseph P. Curilla, Electronics Consulting Laboratory.
Dk1.0001.00062 to 534 to 75 to 98 to 1080
MaterialVacuumAirTypical PlasticsNatural RubberGlassMica Aluminum Oxide (Alumina)Water
Table 1-Dielectric constants of Different Materials*
*Values supplied by Joseph P. Curilla, Electronics Consulting Laboratory.
Dk2.12.22.32.42.63.03.03.13.23.53.74.6
ResinPTFEPolypropylenePolyethylenePolystyreneABSPolycarbonatePETPBTPPSLCPAcetal CopolymerNylon 66
Table 2-Thermoplastic Dielectric Constants*
Source: Plastic Technology,” What we Didn’t Know about Dielectric Properties of Plastics.”K. Reignier et al. (http://www.plasticstechnology.com/articles/200406fa2.html), Feb. 02, 2006,with permission)
FLEXIBLE ELECTRONICS Dielectric Constants of Some Materials and Polymers
FLEXIBLE ELECTRONICS Effect of Dielectric Constant of LCP with Frequency and Filler Addition
Source: Plastic Technology, “What we Didn’t Know about Dielectric Properties of Plastics.”K. Reignier et al. (http://www.plasticstechnology.com/articles/200406fa2.html), Feb. 02, 2006,with permission)
FLEXIBLE ELECTRONICSOrganic Flip Chip Package: HyperBGATM
D1D2D3
D4D5D6
C4 Pads
BGA Pads SignalsVo l tage Planes
A S M
CIC Ground
S1
S2
S3
S4
soldermask
Layer Material Thickness(microns)
Outer Soldermask Epoxy Based Er=3.2
37
S1 and S4 signals Cu 15Voltage Cu 12
S2 and S3 signals Cu 12Ground Cu/Invar/Cu 6/38/6
PTH Barrel Cu OD= 50/ID=34Dielectric Layers D1, D2,
D5, D6PTFE Based
Er = 2.735
Dielectric Layers D3, D4 PTFE Based Er = 2.7
50
FLEXIBLE ELECTRONICS Combining Low Dielectric Constant Materials and Flip Chip Technologies
FLEXIBLE ELECTRONICS Enhanced Wiring Densities in Organic Packages: Hyper-ZeITM
Blind via increases wiring densities
Conductive paste interconnection enhances connectivity
Source: F.D. Egitto, EIT Corp.
FLEXIBLE ELECTRONICS The Near Future: Molecular Transistors
Gate electrode
Organic semiconductor
Gold electrode
MicroencapsulatedElectronic ink
FLEXIBLE ELECTRONICS Toward Paper-Like Displays
Source: J.A. Rogers Science 23, Feb. 23 (2001) p. 1502
FLEXIBLE ELECTRONICS Beyond Flexible Circuits and Laptops
Source: http://www.rense.com/general69/future.htm, March 27, 2006
Optical image of a Test Circuit on Ceramic:
Low magnification view:
FLEXIBLE ELECTRONICS Magnification Scales and Resulting Information
Data are collected from this area
FLEXIBLE ELECTRONICS Surface Analysis Using XPS: Dielectric and Conductive Areas
Point 2
Point 1
OAlC
Cl
C Cr
Cr + O
FLEXIBLE ELECTRONICS Small Spot Sampling with an Electron Beam: AES
FLEXIBLE ELECTRONICSElemental Mapping with X-rays and Electron Beams
X-ray beam
Electron beam
Point 1 on Edge of Line
SED image of line
FLEXIBLE ELECTRONICSIncreasing Magnification Scale by Electron Imaging and AES
Molecular Fluorescence Image FTIR Spectrum of Material and Aromatic Ether Sulfone(Side of metal line)
FLEXIBLE ELECTRONICSIdentification of Contaminant by CLSM and FTIR Methods
Organic contaminant
• Evaluation of working hypotheses on materials interactions• Process and scale-up definitions for products• A means of solving production problems• As part of approaches to answer questions on field returns• As a tool to evaluate competitive product analysis• As a source of documentation on patent litigations and licensing issues
FLEXIBLE ELECTRONICSRelevance of Physical Methods to Characterize Materials
FLEXIBLE ELECTRONICSThe Role of Surface Science in Flexible Circuit Applications
• Definition of sampling depth and its relevance to measured properties• Awareness of materials interactions and interfacial effects• Chemical and mechanical factors that affect interfacial strength:
– Mechanical interlocking and surface roughness – Surface wetting– Acid-base interactions– Method of measurement of interfacial strength and locus of fracture– Environmental effects on materials and interfaces for life prediction
FLEXIBLE ELECTRONICSRelationships Between Characterization Methods and Engineering
Properties of Materials
Mechanical interlocking and surface roughness:
Contact angle:
Acid-Base Interactions:
FLEXIBLE ELECTRONICSRelationships Between Characterization Methods and Engineering
Properties of Materials
Source:A. Kinlock, ed.: Durability of Structural Adhesives, Applied Science Publishers, 1983
FLEXIBLE ELECTRONICSEnvironmental Effects on Practical Adhesion
• Techniques rely on the interaction of energy and matter to produce a measurable result in a time scale (hours to femto-seconds)
• Scales of interactions are determined by range of energy available from a source or sources• Responses that are distinguished from baseline noise can be obtained and in many cases,
theoretically predicted, via models based on first principles• Responses can come from various depths of matter and contributions from various regions may
need to be conveniently separated to provide relevant information to answer a particular question
Thickness Scales Definitions:
Surface Region: 0 to 10 nmSub-Surface Region: 100 to 5 µmBulk region: > 5 µm
Representative Techniques for Analysis:
Surface Region: XPS, AES, SIMS, Reflectance FTIR, AFMSub-Surface Region: RBS, EDS, EMPA, ATR-FTIRBulk: FTIR, Chromatography, ICP, Mass spectroscopy
FLEXIBLE ELECTRONICSBasic Approaches in Materials Characterization
FLEXIBLE ELECTRONICSThe Electromagnetic Spectrum
Source: astro.uiuc.edu~kaler/
FLEXIBLE ELECTRONICSRanges of Materials Characterization Techniques and Sampling Capabilities
Image courtesy of C. Evans & Associates
Consider atoms as spheres attached to springs:
What applies:– Selection rules– Hooke’s law (F=-kx)– Harmonic (E= (½) x kx2) and anharmonic oscillator rules
Basis of Infrared Spectroscopy: Molecules vibrate and produce specific bands (infrared active modes) in their spectra
Basic Instrumental Set-Up:IR source sample Energy discriminator Detector Output
FLEXIBLE ELECTRONICS Vibrational Spectroscopy: Conventional and Fourier Transform Infrared
Types of Infrared Spectroscopy:– Conventional grating systems (original technology)– Fourier Transform systems (Michelson interferometer)– Surface sensitive techniques (reflectance spectroscopy)– Infrared microscopy (absorption and reflectance modes)
Other Useful Techniques in Microelectronic Applications:– Diffuse reflectance spectroscopy (DRIFT)– Attenuated Total Reflectance (ATR)– Photo-acoustic Spectroscopy (PAS)– Group mapping microscopy
Importance of FTIR Techniques:– Surface and bulk analyses are possible– Micro techniques can work to about 10 µm spot sizes– Useful in characterizing polymers and metal surfaces
FLEXIBLE ELECTRONICS Vibrational Spectroscopy: Conventional and Fourier Transform Infrared
FLEXIBLE ELECTRONICS FTIR Spectroscopy: Michelson Interferometer and Signal Patterns
Source: F. Anariba, Ohio State University, with permission
FLEXIBLE ELECTRONICS FTIR Microscopy
Uses of PDMS: Adhesives, lubricant additive, high temperature rubbers,mold release agent
FLEXIBLE ELECTRONICS FTIR Spectra: Fingerprinting Materials
(PDMS)
FLEXIBLE ELECTRONICS Applications of FTIR Microscopy: Transfer Material from Assembly Tool
to Chip Passivation Layer
Source: L.J. Matienzo and D.C. VanHart, EIT
FLEXIBLE ELECTRONICS FTIR Applications: Skin Residues on Gold bonding Pad in a Flexible Circuit
Optical image
EDS spectrum
SE imaging
Source: L.J. Matienzo and D.C. VanHart, EIT
Technique Sampling Probe Lower Sampling Dimension
Light microscopy light 0.2 µm
Confocal LSM light 0.2 µm
SEM electrons 1 nm
TEM electrons 0.1 nm
STM current/voltage 0.02 nm
AFM force 0.02 nm
FLEXIBLE ELECTRONICS Microscopic Techniques
FLEXIBLE ELECTRONICS Cross-Sectional View of Scanning Electron Microscope
Some Critical Considerations:
– Sample imaging requires conductive material– Two dimensional image is obtained by beam rastering at a
given beam voltage– Organic samples may be sensitive to beam damage– Interaction volume is appreciable, however, surface
topography features can be easily observed
Type of information Developed by SEM Modes:
– Secondary electrons give information on topography (SED)– Backscattering mode (BSE) highlights atoms according to their
atomic numbers
SEM and Elemental Identification:
– Coupling of SEM system with Energy Dispersive Detector (EDS) allows the collection of elemental information
– Fluorescence yields low for light atomic elements make their detection in this range less sensitive
F LEXIBLE ELECTRONICS The Scanning Electron Microscope
Primary electron beam
Secondary electrons (surface texture) Auger electrons (0.4 to 5 nm)
Backscattered electrons X-ray emission(Atomic number contrast)
Sample surface
Excitation volume(1-3 m)
FLEXIBLE ELECTRONICS Interactions of an Electron Beam and a Surface
FLEXIBLE ELECTRONICS Surface and Near-Surface Information from a Single UHV Chamber
Source: ub.rug.nl/eldoc/dis/science/n.j.m carvalho.
FLEXIBLE ELECTRONICS Secondary and Backscattering Imaging in SEM
Source: B.L. Pennnigton, EIT
Cu
Spectralresponse
10 KeV
20 KeV
FLEXIBLE ELECTRONICS Energy Dispersive Spectroscopy (EDS) in SEM
Source: B.L. Pennington, EIT
FLEXIBLE ELECTRONICS Elemental Analysis with Energy Dispersive Spectroscopy (EDS)
Source: B.L. Pennington, EIT
HeightInformation
Volume andDimensionalInformation
FLEXIBLE ELECTRONICS The Confocal Principle and Applications of CLSM
Side A
Side B
FLEXIBLE ELECTRONICSCLSM Applications: Electrical Connections in a Multilayer Flexible Board
Source: D.C. VanHart, EIT
FLEXIBLE ELECTRONICS CLSM Applications: Molecular Fluorescence in Polymer Layers
Source: D.C. VanHart., EIT
Scratches on bonding pads
Metal contact across aPolymer film
Source: http://www.beugungsbild.de/stm/stm_basics.html
Source: Department of Experimental Physics, Ulm, Denmark
STM
AFM
FLEXIBLE ELECTRONICS Atomic Microscopies: STM and AFM
FLEXIBLE ELECTRONICS Atomic Microscopies: STM and AFM
Source: Encyclopedia of Materials Characterization, C.R. Brundle, C.A. Evans, Jr, S. Wilson, eds., Butterworth-Heinemann, Boston 1992
Experimental Image Molecular Model of PMDA-ODA
FLEXIBLE ELECTRONICS STM Image of PMDA-ODA Polyimide
Source: Fujiwara, et al. JVST, B, Vol. 9, No. 2, Mar/April 1992
UV/Ozone
O2 Plasma
FLEXIBLE ELECTRONICS AFM Images of a Surface-Modified Biopolymer Film
Source: L.J. Matienzo and S.W. Winnacker, Macromolec. Mater. Eng., 287, 871(2002)
he e
hv or e
ion He+ ion ion He+ ion
h e x-ray x-ray
XPS AES
SIMS RBS
XRF EMPA
FLEXIBLE ELECTRONICS Surface and Near-Surface Spectroscopies
Basis of technique:Collision of accelerated particle at high energy (MeV) with a nucleus induces
energy transfer to target and detection of process is done through nuclear particle detector.
FLEXIBLE ELECTRONICS Rutherford Back Scattering Spectroscopy (RBS) Fundamentals
FLEXIBLE ELECTRONICS RBS Applications: Stoichiometry of a Cermet Film
Source: L.J. Matienzo, et al., Thin Solid Films, 204, 265 (1989)
Source: L.J. Matienzo, et al., Proc. 34th Soc. Vac. Coaters Meeting, p. 247, Philadelphia, PA (1991)
FLEXIBLE ELECTRONICS RBS Applications: Copper Thickness on a Polyimide Substrate
:
Photo emission Shake-up Auger process X-ray fluorescence
FLEXIBLE ELECTRONICS XPS and AES: Excitation and De-Excitation Processes
Source: L. Karlsson, Department of Physics, Uppsala University, Sweden
FLEXIBLE ELECTRONICS XPS and AES: Multipurpose UHV Chamber
B
A, B, and C are sampled A and C are sampled C is only sampled
CA
Slit size
FLEXIBLE ELECTRONICS Beam Size Selection and Appropriate Sampling
N+
NSi
FLEXIBLE ELECTRONICS Surface Modified Glass Fiber with a Silane Coupling Agent
Source: L.J. Matienzo, unpublished results
Plasma treated polymer
Plasma treated polymer
FLEXIBLE ELECTRONICS Chemical Group Mapping with XPS: Areas of a Flex Module
Source: L.J. Matienzo, unpublished results
Image source: www.physik.uni-jena.de/ ~layer/techniques/AES.HTML
Integratedsignals
Derivativesignals
FLEXIBLE ELECTRONICS Auger Electron Spectroscopy and Resulting Spectra
FLEXIBLE ELECTRONICS AES Point Analysis of a Complex Surface
Source: L.J. Matienzo, unpublished results
Ethyl trifluoroacetate
C1s region,expect 4 differentcarbon environments with equivalent areas
B.E. shifts are given by different + (charge) on carbon atoms
Expect two different O1s environments with area ratios of 1-to-1
Note: Reference on XPS data is the position of C-C or C-H bonds located at 284.6 eV
Source: Siegbahn et al.Nova Acta Regiae Soc. Sci. Ups. 20:7(1967)
FLEXIBLE ELECTRONICS High Resolution XPS Spectra
2-(4-nitrobenzenesulfonamide)
N1s region contains three differentenvironments with equivalent areas
S2p region will include a single doublet
Source: Siegbahn et al.Nova Acta Regiae Soc. Sci. Ups. 20:7(1967)
FLEXIBLE ELECTRONICS High Resolution XPS Spectra
FLEXIBLE ELECTRONICS High Resolution XPS Spectra for Deposition of Dithiols on Gold Surfaces
Source: L.J. Matienzo, unpublished results
2
1
h or e-
h or e-h or e-
Ar+ Ar+
Stationary sputtering Dynamic sputtering (Zalar)
Variable angle
FLEXIBLE ELECTRONICS Non-Destructive and Destructive Depth Profiling
FLEXIBLE ELECTRONICS Non-Destructive Depth Profiling of Aluminum Surface
Source: L.J. Matienzo, unpublished results
65 degrees
30 degrees
15 degrees
Oxidized Al
Al metal
h
12
Oxidized Al
Al metal
Al2p region
FLEXIBLE ELECTRONICS Destructive Depth Profiling: Tantalum Oxide on Tantalum Metal
Source: L.J. Matienzo, unpublished results
FLEXIBLE ELECTRONICSAES Imaging and Depth Profiling: Nickel Spheres on In Foil
Source: PHI, USA
FLEXIBLE ELECTRONICSAES Imaging and Depth Profiling: Nickel Spheres on In Foil
Source: PHI, USA
+ +
--
The incident beam can induce loss of neutral atoms and positively and negatively charged fragments
Silicon Surface
Before Bombardment After 3 x 1012 ion/cm 2
FLEXIBLE ELECTRONICSSecondary Ion Mass Spectroscopies: Static and Dynamic SIMS
Specific spectral analysis
Ion imaging
Depth profiling
FLEXIBLE ELECTRONICSThe Uses of Static and Dynamic SIMS
FLEXIBLE ELECTRONICSSecondary Ion Mass Spectroscopy : Positive and Negative Spectra of Teflon
FLEXIBLE ELECTRONICSIon Mapping of Polyvinyl Alcohol Contaminant on a PET Surface
Source: PHI, USA
Technique useful and provides:
1) Thickness of Ge layer2) Concentration of dopant (B)3) Impurities or other additives4) Depth of modification5) Good spatial resolution6) Fast rate of profiling
FLEXIBLE ELECTRONICSD-SIMS Profiling of a Si-Ge Thin Gate Structure
Source: PHI, USA
FLEXIBLE ELECTRONICSA Comparison of Surface-Sensitive Techniques for Materials Characterization
FLEXIBLE ELECTRONICSSome Applications of Physical Methods to the Characterization of
Polymeric Materials in Microelectronic Applications
• Polyimide Films in the fabrication of TBGA circuits
• Optimization of lamination processes for fluoropolymer composites
• Application of dry process modification methods to biopolymers
• Segregation, surface modification and adhesion of polyimide films
FLEXIBLE ELECTRONICS Design of a Flexible Circuit in an Electronic Package: Example 1
Attributes of Desired Final Product
• Adhesion of metal lines to polymer substrate should be 20 gm/cm as a minimum• Use of high temperature stable polymer as the dielectric layer• Use a solvent-based photo-imaging system for line definition• Copper layer should be protected by a gold overlayer applied by electro-deposition• After die attachment, the package will be encapsulated• Encapsulated package must have a minimum adhesion level of 20 gm/cm after 200 hours at
85% R.H./80°C
Cross-Sectional View of Encapsulated Circuit
Source: L.J. Matienzo and F. D. Egitto, Solid State Technol., 38, 99(1995)
FLEXIBLE ELECTRONICS Flexible Circuits in Grid Ball Array Applications
FLEXIBLE ELECTRONICS Some Flexible Circuit Manufacturing Processes
roll metallized material
Cr/Cu deposition
load vacuum chamber
Ar gas into
chamber
O2 plasma
FLEXIBLE ELECTRONICS Semi-continuous Process for Polymer Metallization
FLEXIBLE ELECTRONICS Surface Modification of a Polyimide (PMDA-ODA) Film
Source: L.J. Matienzo and F. D. Egitto, Solid State Technol., 38, 99(1995)
L.J. Matienzo and W.N. Unertl, Polyimides Fundamentals and Applications, M. Ghosh and K.L.Mittal, eds. Marcel Dekker, New York (1996) and F.D. Egitto et al., J. Adh. Sci. Technol., 8, 411 (1991)
FLEXIBLE ELECTRONICS Measuring Effectiveness of Surface Modification of Metallized Films
Weak BoundaryLayer
Microwave Plasma D.C. Glow Plasma
MechanicallyStrong Layer
FLEXIBLE ELECTRONICS Surface Modification and Integrity of Polymeric Films
Kapton Side of Peel
T0
T168
Source: L.J. Matienzo et al., unpublished results
FLEXIBLE ELECTRONICS Measuring Environmental Performance of Metallized Films
FLEXIBLE ELECTRONICS Characterization of Fracture Modes on Metallized Films
L.J. Matienzo et al., J. Vac Sci. Technol. A9, 1278 (1991)
Cl
No temperature Exposure
After bake in MeCl
L.J. Matienzo et al., J. Vac Sci. Technol. A9, 1278 (1991)
FLEXIBLE ELECTRONICS Failure Mechanisms of PI/Cr/Cu Metallized Films Solvent
CuCrPI
0 50 100 150 200
0
0.5
1
1.5
Diff
eren
tiate
d S
igna
l Cou
nts
(x 1
0 )4
Distance ( m)
Potassium Ion Distribution Across Peeled Line from AES line scans (Polymer side)
Source: L.J. Matienzo et al., unpublished results
FLEXIBLE ELECTRONICS Electrochemical Susceptibility of PI Films During Gold Deposition
K Based Gold Salt Ammonium Based Gold SaltK [Au (CN)4 ] (NH4) [Au (CN) 4 ]
FLEXIBLE ELECTRONICS Resulting Adhesion After Gold Deposition Using Different Gold Plating Salts
Source: L.J. Matienzo et al., unpublished results
FLEXIBLE ELECTRONICSA Case Study in Process Optimization: Flexible Polyimide Circuits
• Adhesion of metal to polymer was enhanced by surface oxidation of polymer • Ion bombardment during surface modification enhanced mechanical properties of
dielectric film• Other fabrication process beyond metallization affected metal/polymer adhesion• Adhesion loss was enhanced in humid environments• Additional reactions of residual chemicals can affect overall metal/polymer adhesion• Polymers can also be altered via electrochemical reactions• Optimized engineering design of interface can yield expected specifications
(Summary of Example 1)
SiO2
Surfactants andCoupling Agents
PTFE polymer chain
FLEXIBLE ELECTRONICSLamination Processes for Fluoropolymer (PTFE) Composites: Example 2
Unfilled PTFE
PTFE Composite
Source: L.J. Matienzo and D. Farquhar, unpublished results
F
F~~~~~~
Cr CuPTFE-SiO2Cr Cu
~~~~~~Cr CuPure PTFE Cr Cu
PTFE orPTFE-SiO2
Cr Cu
FLEXIBLE ELECTRONICSLamination Processes for Fluoropolymer (PTFE) Composites and PTFE Films
Source: L.J. Matienzo and D. Farquhar, unpublished results
FLEXIBLE ELECTRONICSSEM Images of Fractured Interfaces for a Composite
METAL SIDE POLYMER SIDE
METAL SIDE POLYMER SIDE
354.4°C
379.4°C
Source: L.J. Matienzo and D. Farquhar, unpublished results
1.0
0
1.0
0
1.0
0
1.0
0
300290
280
700690
800
545535
525600
580
Binding Energy (eV) Binding Energy (eV)
Binding Energy (eV0 Binding Energy (eV)
Nor
mal
ized
Inte
nsity
Nor
mal
ized
inte
nsity
Nor
mal
ized
Inte
nsity
Nor
mal
ized
Inte
nsity
12
3
12
3
12
3
12
3
C1s F1s
O1s Cr2p
FLEXIBLE ELECTRONICSXPS Spectra of Fractured Interfaces: Metal Sides vs. Temperature
Increasing Temperature
Source: L.J. Matienzo and D. Farquhar, unpublished results
300290
280
545535
525
700690
680
1.0 1.0
1.0
0 0
0
Nor
mal
ized
inte
nsity
Nor
mal
ized
Inte
nsity
Nor
mal
ized
Inte
nsity
C1s F1s
O1s
1
23
1
23
1
23
Binding Energy (eV) Binding Energy (eV)
Binding energy (eV)
FLEXIBLE ELECTRONICSXPS Spectra of Fractured Interfaces: Polymer Sides vs. Temperature
Increasing Temperature
Source: L.J. Matienzo and D. Farquhar, unpublished results
1
354.4°C
365.6°C
379.4°C
290280
300Nor
mal
ized
Inte
nsity
Binding energy (eV)
C1s
300290
C1s
PTFE
composite
FLEXIBLE ELECTRONICSC1s XPS Spectra of PTFE and Composite Films at Various Temperatures
Nor
mal
ized
Inte
nsity
Binding energy (eV)
25°C
-CF2-
-C-C/-C-H
Source: L.J. Matienzo and D. Farquhar, unpublished results
0
100
200
300
400
500
600
354.4 365.6 379.4
Lamination Temperature (°C)
PTFE
PTFE with SiO2
Failure Strain(%)
FLEXIBLE ELECTRONICSUniaxial Tension Results for PTFE Film and Composite Film
Source: L.J. Matienzo and D. Farquhar, unpublished results
Cr Cu
Cr Cu
PTFE
SEM; XPS
as laminated after etching
Nor
mal
ized
Inte
nsity
1.0
0300
290
280Binding Energy (eV)
1
2
3
C1s
FLEXIBLE ELECTRONICSPTFE Surface After Metal Removal (Post Lamination)
Increasing temperature
Source: L.J. Matienzo and D. Farquhar, unpublished results
7 6 5 4 3 2 1
300
290
280 76
54
32
Binding Energy (eV)
Nor
mal
ized
Inte
nsity
1.0
0
C1s
PTFE Film
FLEXIBLE ELECTRONICSMicrotome Slice and XPS Point Analysis for Sample Laminated at 379.4°C
Source: L.J. Matienzo and D. Farquhar, unpublished results
0
2628
354.4 365.6 379.4Lamination Temperature, °C
Peelstrength
(N/m) 2628
354.4 365.6 379.4Lamination Temperature, °C
Peelstrength(N/m)
0
FLEXIBLE ELECTRONICSPeel Strengths for PTFE/Metal and FP-SiO2 Composite
Source: L.J. Matienzo and D. Farquhar, unpublished results
FLEXIBLE ELECTRONICSModel for Cracking on Metal/Fluoropolymer Composite
Source: L.J. Matienzo and D. Farquhar, unpublished results
(Summary of Example 2)
Rationale:• Alternative to petroleum derived polymers• Mixtures of this polymer and a synthetic polymer increase biodegradability• A potential for a “Green Product” from second larger biomass available• Potential model for modification of a biomaterial• Dry processes of modification offer possibility for cleaner material thanthose produced by solution modification
Source: L.J. Matienzo and S.W. Winnacker Macromolec. Mater. Eng., 287, 871(2002)
FLEXIBLE ELECTRONICSModification of a Bio-Polymer Film (Chitosan): Example 3
Source: L.J. Matienzo and S.W. Winnacker Macromolec. Mater. Eng., 287, 871(2002)
FLEXIBLE ELECTRONICSXPS Analysis of a Thin Chitosan Film on an Al/Si Wafer
Chitosan is a biopolymer derived from chitin with x = 0.33 and y = 0.67
FLEXIBLE ELECTRONICSA Comparison Between 13C CP-MAS NMR and C1s XPS Results
C2 + C6 + C8
C3 + C4 + C5
C1
C7
C1s region
Source: A.A. de Angelis et al., Macromolecules 31, 1595 (1998) and L.J. Matienzo and S.W. Winnacker Macromol. Mater. Eng. 281, 871(2002)
C1s region
65°
45°
20°0 10 20 30 40 50 60 70
Take-Off Angle (degrees)
102030405060708090
100
Estim
ated
Thi
ckne
ss (A
)
Estimated Polymer Thicknessvs Take-Off Angle
d = 3 sin( )
d
FLEXIBLE ELECTRONICSVariable Angle XPS and Overlayer Effects For a Thin Film of Chitosan
Source: L.J. Matienzo and S.W. Winnacker, Macromolec. Mater. Eng., 287, 871(2002)
FLEXIBLE ELECTRONICSModification of a Biopolymer by Dry-Processes: Non-RIE Plasma,
RIE Plasma and UV/Ozone
Source: L.J. Matienzo and S.W. Winnacker 24th Latin American Chemistry Congress Proceedings, Lima, Peru (2000)
FLEXIBLE ELECTRONICSRIE Plasma and UV/Ozone Results Followed by XPS: Chitosan
RIE Oxygen Plasma UV/Ozone
Source: L.J. Matienzo and S.W. Winnacker Macromolec. Mater. Eng., 287, 871(2002)
Segment x is the only one affected by UV/ozone irradiation and one would expect an enhancementof carbonyl groups as the XPS spectra of the C1sregion show. In addition, molecular weight decreasesas a function of irradiation time
FLEXIBLE ELECTRONICSMechanism of Modification by UV/Ozone Surface Reaction
FLEXIBLE ELECTRONICS Evaluating Topography of a Surface-Modified Biopolymer: AFM and SEM
UV/Ozone
O2 Plasma
UV/O3
Surface reaction
Oxidized region
Oxidized zone can react with asilane coupling material
CF3 CF3 CF3
UV/O3
SiOx barrier
Carbonyls, hydroxyl groups, etc.
FLEXIBLE ELECTRONICSChanging Hydrophobic and Hydrophilic Responses by Surface Reactions
Source: L.J. Matienzo and S.W. Winnacker 24th Latin American Chemistry Congress Proceedings,Lima, Peru (2000)
OH
OH
OH
(CH3O)3SiCF3
+ SiOCF3
O
O+ CH3OH3
Controlled oxidation of surface silicon-containing materials
FLEXIBLE ELECTRONICSPhase Separation Approaches in Surface Modification: Example 4
Applications to the Formation of Thick Polyimide Films
• PI films are usually made by spin casting from solvents and subsequent reaction curing
• Spin casting of polyimide is typically limited to thicknesses below 1 µm•Thicker layers of polyimide over a substrate can be formed but typicaladhesion of interfaces is weak without surface modification
•Surface modification of polyimides is usually done by basic hydrolysis
Concern: Alpha emission of filler particles in materials can induce soft error rates in electronic devices
What is needed: A method by which a thick polyimide layer is formed with minimal contamination of stack and excellent inter-layer adhesion
FLEXIBLE ELECTRONICSThick Polymeric Films of Polyimide
γ PDMS = 0.024 N/m
γ PI = 0.040 N/m
Segregation of PDMS
(a)
(b)
Liquid-Applied PI
Transformation with UV/Ozone
(c)
Application and Cure of Second PI Layer
DI Water Contact Angle = 104(Undoped PI = 70 )
"Glassy" PI SurfaceDI Water Contact Angle = 5
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)
PDMS
PMDA-ODA Polyimide
-O-
OC
N-CO
OC
NCO
R is CHR' is OH
R R RR-Si- -O-Si- -O-Si-R'
R R Rn3
FLEXIBLE ELECTRONICSThick Polymeric Films of Polyimide
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)
Materials:
Approach: Phase separation and surface modification of resulting films
FLEXIBLE ELECTRONICS PMDA-ODA Films Modified by Various Processes: Efficiency of
Moisture Barriers
Time (min)
2 min Plasma Treatment
60 min UV/OzoneTreatment
0.01 0.1 1 10 100 1000 10000 1000000
20
40
60
80
100
120UV/OzonePlasma (RIE)Plasma (No Ions)
Adv
anci
ng D
I Wat
er C
onta
ct A
ngle
(deg
rees
)
F.D. Egitto, L.J. Matienzo, and B.O. Morrison, Jr. US Patent 5693928, December 12, 1997
300 298 296 294 292 290 288 286 284 282 280 Binding Energy (eV)
1.81.61.41.21.00.80.60.40.2 0
Nor
mal
ized
Inte
nsity
Figure 4
FLEXIBLE ELECTRONICSThick Polymeric Films of Polyimide
C1s XPS spectra of PMDA-ODA and Blended Films with PDMS
0.75% PDMS
0.25% PDMS
0.00% PDMS
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)
0 5 10 15 20
0 5 10 15 20
Time (min)
0
20
40
60
80
100
0
20
40
60
80
100
Con
tact
Ang
le (d
egre
es) 0.25% PDMS
0.75% PDMS
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
Advancing contact Angle as a Function of UV/Ozone Treatment
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)
300 298 296 294 292 290 288 286 284 282 280 Binding Energy (eV)
1.81.61.41.21.00.80.60.40.2 0
Nor
mal
ized
Inte
nsity
60 minutes
20 minutes
5 minutes
0 minutes
C1s region on PMDA-ODA/PDMS (0.25%) BLEND
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
C1s XPS Spectra as a Function of UV/Ozone Treatment Time
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)
Figure 5b
300 298 296 294 292 290 288 286 284 282 280 Binding Energy (eV)
1.5
1.0
0.5
0
Nor
mal
ized
Inte
nsity
300 298 296 294 292 290 288 286 284 282 280 Binding Energy (eV)
1.2
1.0
0.8
0.6
0.4
0.2
0
Nor
mal
ized
Inte
nsity
h
12
15°30°65°
15°30°65°
0.25% PDMS in PMDA-ODA
0.75% PDMS in PMDA-ODA
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
Variable Angle C1s XPS Spectra of PMDA-ODA/PDMS
414 412 410 408 406 404 402 400 398 396 394 Binding Energy (eV)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
Nor
mal
ized
Inte
nsity
414 412 410 408 406 404 402 400 398 396 394 Binding Energy (eV)
2.0
1.5
1.0
0.5
0
Nor
mal
ized
Inte
nsity
h
12
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
Variable Angle N1s XPS Spectra of PMDA-ODA/PDMS
0.25% PDMS in PMDA-ODA
0.75% PDMS in PMDA-ODA
15°
30°
65°
300 298 296 294 292 290 288 286 284 282 280 Binding Energy (eV)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
Nor
mal
ized
Inte
nsity
414 412 410 408 406 404 402 400 398 396 394 Binding Energy (eV)
1.2
1.0
0.8
0.6
0.4
0.2
0
Nor
mal
ized
Inte
nsity
C1s region
N1s region
60 minutes
5 minutes
0 minutes
60 minutes
5 minutes0 minutes
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
C1s and N1s XPS Spectra for PI as a Function of UV/Ozone Treatment Time
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)
116 114 112 110 108 106 104 102 100 98 96 94 Binding Energy (eV)
2.0
1.5
1.0
0.5
0
Nor
mal
ized
Inte
nsity
Si2p region
414 412 410 408 406 404 402 400 398 396 394 Binding Energy (eV)
Nor
mal
ized
Inte
nsity
1.81.61.41.21.00.80.60.40.2 0
N1s region
60 minutes
20 minutes5 minutes
0 minutes
60 minutes
20 minutes5 minutes
0 minutes
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
Si2p and N1s XPS Spectra as a Function of UV/Ozone Treatment Time
C-Si-O
Si-O ∆ B.E.
400 nm 400 nm 400 nm
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
SEM Images for PMDA-ODA Blends Before and After Treatment in UV/Ozone
0.25% PDMS blend, no treatment 0.25% PDMS blend, 5 minutes 0.75% PDMS blend, 5 minutes
Source: B.L. Pennington, EIT
0.20.4
0.60.8
1.0 m
30 nm
0.20.4
0.60.8
1.0 m
30 nm
0.20.4
0.60.8
1.0 m
30 nm
0.20.4
0.60.8
1.0 m
30 nm
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
AFM Images of Films as a Function of UV/Ozone Treatment Time
0% PDMS, no treatment
0.25% PDMS, no treatment
0.25% PDMS, 5 minutes
0.25% PDMS, 60 minutes
0 0.25 0.50 0.75 1.00m
nm
-10.
0
0
10.0
L 306.6 nmRMS 1.74 nmlc DCRa(lc) 1.24 nmRmax 7.97 nmRz 3.28 nmRz Cnt validRadius 436.1 nmSigma 7.93 nm
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
AFM Image Profile of Film Containing 0.25% PDMS
A -1100 adhesion promoter
silicon
polyimide blend or polyimide
new polyimide
FLEXIBLE ELECTRONICS Thick Polymeric Films of Polyimide
Cross-sectional View of Samples for Adhesion Testing
pattern of cut
peel on PI-PDMS
peel on PI
pattern of cut
peel on PI-PDMS
peel on PI
(b)(a)
Source: L.J. Matienzo and F.D. Egitto J. Mater. Sci, in press (2006)