Application of Surface Analysis for Root Cause Failure ... · Specialists in Materials Characterization David A. Cole Evans Analytical Group East Windsor, NJ Application of Surface

Specialists in Materials Characterization

David A. ColeEvans Analytical Group

East Windsor, NJ

Application of Surface Analysis for Root Cause Failure Analysis

AIMCAL - Oct 21, 2008 © Copyright 2008 Evans Analytical Group LLC 2

• Introduction

• X-Ray Photoelectron Spectroscopy/ Electron Spectroscopy for Chemical Analysis (XPS/ESCA)

– Additive Migration

– Adhesion Failure

• Time-of-Flight Secondary Ion Mass Spectrometry(TOF-SIMS)

– Backside Transfer

– Ghost Image

• Summary

Outline


• Techniques provide both organic and inorganic information to varying extents.

• Techniques are unique in providing direct chemical bonding information.

• With hundreds of thousands of organic compounds, this information can be very important for problem solving or evaluation.

• One thing to remember about any organic analysis method: these techniques only evaluate the existing chemistry of the sample.

Introduction


X-ray

Sample~10 μm

XPS Process

e-e-

e-

Photoelectrons characteristic of sample surface

SamplingDepth1 -10 nm


• Measure kinetic energy (KE) of photoelectrons ejected from sample

• Calculate photoelectron binding energy (BE) in electron volts, eV

BE = hν – KE – φ + δhν = excitation x-ray energy (fixed energy)φ = electron spectrometer work functionδ = net surface charge

• Survey spectrum: identifies elements at surface

• High resolution spectrum: identifies chemical state from peak position and peak shape

XPS Technique


X-Ray Photoelectron Spectrometer

X-ray Source Electron Analyzer

Quartz CrystalMonochromator

X-rays

HemisphericalEnergy Analyzer

ElectronDetector

Al Anode Sample

ElectronSource Ultra-High Vacuum Chamber


• Background:

– Sporadic adhesion failure was observed with a polypropylene film.

– Film contained erucamide• C22H43NO

• C = 91.7atom%,

• N = O = 4.2 atom%

• Questions:

– What is the surface concentration of erucamide as a function of storage conditions?

Additive Migration

NH2

XPS


Additive Migration

Film aged 23 days at room temperature

Binding Energy (eV)

XPS


Additive Migration

Film aged 9 days at 120°F

Binding Energy (eV)

XPS


Additive Migration

0 5 10 15 20 250

1

2

3

RT

120°F

Nitr

ogen

Con

cent

ratio

n (a

tom

%)

Storage Time (days)

XPS


• Conclusions:

– Surface erucamide concentrations are higher than the bulk film as produced.

– At room temperature migration is slow

• increasing 60% after 23 days.

– Migration is rapid at 120°F

• Increasing 450% in 1.5 days

• Erucamide layer is ~2 nm thick!

Additive MigrationXPS


Adhesion Failure

• Background:– Metalized PVC film passed 610 tape pull test

– But fully processed label appeared to fail between PVC film and Al layer

• Questions:– What is the locus of failure?

– What is the cause of failure?

InkAluminum

Clear PVC Film

AdhesiveRelease Liner

Clear PVC Top Coat

XPS


Adhesion Failure

Bad sample Good sample

Adhesive backed PVC film

Metallized top coat

XPS


Adhesion Failure

Concentration (Atom%)

Bad sample: Adhesive failure at PVC - Al interface

Good sample: Cohesive failure at PVC - Al interphase

XPS

Sample C Cl O Al Sn N NaBad - PVC Film 68.5 28.9 2.5 - <0.1 - <0.1Bad - Top Coat 26.0 3.5 38.4 31.4 0.1 0.2 0.3

Good - PVC Film 71.8 25.5 2.7 - <0.1 <0.1 -Good - Top Coat 55.3 10.0 22.7 11.3 <0.1 0.7 -

PVC - theory 66.7 33.3 - - - - -


294 292 290 288 286 284 282 280

Nor

mal

ized

Inte

nsity

Binding Energy (eV)

Top Coat

Adhesion FailureCarbon 1s spectra

C-C, C-O, & O-C=O bonds due to plasticizerC-O & C=O bonds due to plasma treatment

PVC Film

C-C & C-Cl bonds due to PVC

C-CC-O

O-C

=O C=O

C-C

l

C-C

O-C

=O

C-C

C-C

l

XPS

Sample C Cl O

Bad 68.5 28.9 2.5

Good 71.8 25.5 2.7

Sample C Cl O Al

Bad 26.0 3.5 38.4 31.4

Good 55.3 10.0 22.7 11.3

294 292 290 288 286 284 282 280

Nor

mal

ized

Inte

nsity

Binding Energy (eV)

BadGood

BadGood


• Conclusions:– Good sample has mixed mode failure

• Within the PVC – Al interphase• Within the top coat

– C-O & C=O bonds in good sample are evidence of plasma treatment

– Bad sample exhibited adhesive failure at PVC - Al interface• Interface contains plasticizer• Little evidence of plasma treatment

– Tin stabilizer detected but probably not a significant cause of failure

– Review of plasma modification records revealed the power was ~5X too low for bad sample

Adhesion FailureXPS


XPS can detect and quantify all elements except for H and He, and provide chemical state information; making it a powerful survey analysis technique

XPS/ESCA Summary


Dynamic SIMS Static SIMS

• Material removal• Elemental analysis• Profiling

• Ultra surface analysis• Elemental or molecular analysis• Analysis complete beforesignificant fraction of moleculesdestroyed

Analytical Modes of SIMS


Sample

3kV

Pulsed Primary Ion Source

Detector

Secondary Ions

Measure spectrum in flight time: t2 = ½ m l2 / q V

Convert time axis to mass: m = at2 + b

KE = q V = ½ mv2 = ½ m l2 / t2

Light ions arrive at the detector first, with sequentially heavier ions following later in time. Each pulse of primary ions produces a full mass spectrum of secondary ions

Time-of-Flight SIMS: Basic Principles

Ultra High Vacuum Chamber

Tube length = l


Primary Ion Beam

Sample

m/z

Total Area SpectrumTotal Ion Image

Chemical Map 2

Chemical Map 1

m/z

Region 2 Spectrum

m/z

Region 1 Spectrum

Spectra & Images

Typical TOF-SIMS Data


• Background:– Adhesion failure when coating a metallized

polyolefin film.

• Questions:– What caused failure?

– What was the source?

Backside TransferTOF-SIMS

Layer with Irganox® 1010Al metallization

Layer without Irganox® 1010



M = C73H108O12 = 1176.78 amu

M-H = 1175.81

H

M-H = 1175.78 m/zM-C14H23O = 969.61 m/z

C14H23OM-C17H25O2 = 915.60 m/z

C17H25O2

M-C14H23O

M-C17H25O2

M-H

Irganox® 1010


• Conclusions:

– Irganox® 1010 was detected on both sides of the metallized film.

– Irganox® 1010 migrated to the surface of the polymer layer during processing.

– Irganox® 1010 transferred to the metallized surface during reroll/storage.



• Background:

– Refrigerated food package exhibited ghost printing due to water condensation

– Film was stated to be a polyolefin

• Questions:– What caused water condensation?

Ghost Image


Ghost Image

Survey Spectra

XPS

Atomic Concentration of ElementsArea C O N SiControl 84.8 15.2 - -Ghost 89.8 8.5 0.6 1.2

Control Area

Oxy

gen Car

bon

Binding Energy (eV)

1200 1000 800 600 400 200 0

Nitr

ogen

Silic

on

Ghost Area

Oxy

gen

Car

bon

Binding Energy (eV)

1200 1000 800 600 400 200 0


Ghost Image

High Resolution Spectra

Carbon Functional Groups (atom%)

XPS

Binding Energy (eV)

Silicon

silic

one

Ghost Area

112 110 108 106 104 102 100 98 96

Area C-(C,H,Si) C-(O,N) O-C=OControl 67.3 14.8 2.6Ghost 83.1 5.7 0.9

Binding Energy (eV)

Nitrogen

408 406 404 402 400 398 396 394

Ghost Area

C-N

292 290 288 286 284 282Binding Energy (eV)

Carbon

Control AreaGhost Area

C-(C

,H,S

i)C-(O

,N)

O-C

=O


Ghost Image

Control area is covered with glycerol monooleate

TOF-SIMS

Control AreaGMO-OH

GDO-OH

GM

O-C

H3O

2

GM

O-C

3H7O

3

100 200 300 400 500 600


Ghost Image

Ghost area also contains polydimethyl siloxane and stearamide

TOF-SIMS

Ghost AreaPDMS

Stearamide +H

100 200 300 400 500 600

PDMS GMO-OH

GDO-OH


• XPS results:– Film surface was covered with a compound containing

C-O and O-C=O groups.– Contaminants in the ghost area were silicones and

amines/amides.

• TOF-SIMS results:– Film coating as glycerol monooleate– Contaminants as polydimethyl siloxane and

stearamide.– Stearamide is localized to specific areas.

• Contaminants are from printing inks transferred during reroll/storage.

Ghost Image


TOF-SIMS is a very surface sensitive technique providing fullElemental and molecular analysis with excellent detection limits.

TOF-SIMS Summary


• XPS:– Quantitative elemental and chemical bonding analyses

– Sampling depth 1 to 10 nm (3 to 30 monolayers)

– Analysis of any vacuum compatible sample

– Often the first look technique for organic materials

• TOF-SIMS:– Compound identification

– Sampling depth ~1 nm (~3 monolayers)

– ppm detection of elemental surface composition

– Analysis of any vacuum compatible sample that is reasonably flat

– Rapid imaging with sub-micron spatial resolution

Summary


• Evans Analytical Group

• Anonymous clients

Acknowledgements

Documents

Application of Surface Analysis for Root Cause Failure ... · Specialists in Materials Characterization David A. Cole Evans Analytical Group East Windsor, NJ Application of Surface