recent developments in nanoscale mechanical property testing high temperature testing and impact...

MEASURING NANOTECHNOLOGY

MICROMATERIALS

Recent Developments in Nanoscale Mechanical Property Testing

High Temperature Testing and Impact Testing

Dr Krish Narain, Dr Ben Beake and Dr Jim Smith,

Micro Materials Ltd. Wrexham, UK.

Bringing nanomechanicalmeasurements into the real-world


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NanoTesting techniques

• Nanoindentation • Nano-scratch testing

• Impact testing*• Contact fatigue testing*• Dynamic hardness testing*

• High temperature testing*

* = Micro Materials techniques – Worldwide patents pending


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Nanomechanical property testing at high temperatures

The NanoTest high temperature stage

Hot stage specifications

• Indentation to 500 degrees Celsius• Scratch testing to 500 degrees Celsius• Thermal drift minimal

Horizontal loading configuration has advantages for drift-free high temperature tests


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All materials exhibit temperature-dependent mechanical properties

…thermal and mechanical cycling can lead to increasedresidual stresses, particularly where materials have dissimilar thermal properties

Material CTE (10-6/oC)CVD Diamond 2.0Beryllium Oxide 7.4Aluminium Nitride 3.2Silicon 3.0Copper 16.8Gold 14.3

Properties of Electronic Device and Packaging Materials

• testing at service temperature is necessary for optimisation

Why is high temperature testing important?

…particularly where coating-substrate CTE mismatch is an issue…


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High temperature nanoindentation testing of fused silica

Thermal drift measured at 90 % unloading.

Thermal drift would be shownby discontinuities in unloading curves at 90 % unloading…

…minimal thermal drift

Higher testtemperatures


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High temperature nanoindentation testing of fused silica

Thermal drift normallyvery low – some smalldrift at 300 deg. C shownby the discontinuity at 90 %unload

Usually thermal drift at elevated temp is as low asroom temp (due to the thermalisation time and thehorizontal configuration)


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Hardness and modulus results for fused silica

FS shows increasingModulus with temp…

…agrees with modulus determinations by beam-bending methods

FS is an “anomalous glass”


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Hardness and modulusdecrease with increasing Temperature on soda-lime glasses…


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• Softening parameters• Tg determination on ultra-thin films

Applications


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High temperature nanoindentation testing

Temp/0C H/GPa Er/GPa25 0.84 86.3200 0.59 74.1400 0.38 68.8

Indentation to 50 mN on gold

• temperature-dependent phase changes• repeat indentations• thermal cycling• studies of creep processes• loss and storage moduli

Applications include...


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NanoTest impact module

for…

• Impact testing• Contact fatigue testing• Erosive wear testing• Fracture toughness• Adhesion testing• Dynamic hardness

The only commercial nano-impact tester available

Impact


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Impact testing - simulating fatigue wear and failure

• adhesion failure• fracture

Impact


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Impact Testing of a brittle TiN coating

• For bulk materials wear rates are determined from changes in probe depth

• For coatings, time-to-failure is related to the bonding strength to the substrate

100 mN applied load ison throughout test

80 Hz oscillation frequency

Oscillation on 30 s after startOscillation off 30 s before end

Film failure after 250 s

Impact


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Contact fatigue testing

Information obtained:

1/ time to failure (durability)

2/ type of failure(adhesive/cohesive/mixed)

An accelerated test to mimic the mechanical fatigue cycles which circuit boards and ME devices are subject to in service

Applied Load

test probe

film 1

film 2/subsrate

piezoelectric orpendulum impulsesampleoscillation

• Assess adhesion/delamination (e.g. between metal-dielectric)• Investigate fracture behaviour


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Contact fatigue testing of conductive ITO coatings

423 nm

more conductive ITO coating less conductive ITO coating

the less conductive coating shows• more brittle fracture• larger change in depth

349 nm


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AIM: to use the pendulum impulse technique to determine the effect of deposition power on impact resistance of DLC coating on Si wafers

Pendulum impulse - DLC

...film thickness is similar for all 3


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• Quantification of adhesion energy• Determination of total energy delivered to contact point• Dynamic hardness measurement

Static ForceImpact AngleAcceleration distanceImpact FrequencyTest probe geometry

Advantage of the impulse technique:The energy imparted to the sample surface can be calculated at any given time point, since the force is known (static load applied throughout the test), and the displacement is also recorded.

Experimental variables include:Operating principle...



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Test conditions for all samples:-1 mN applied load8 repeat impact tests of 30 min each (on different areas of the samples)


differentiate samples by... • time to failure• type of failure

105 W sample exhibited cohesive failure in only 12.5 % of tests

Illustrative behaviour on sample deposited at 105 W RF power


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115 W sample exhibited cohesive failure in 37.5 % of tests



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125 W sample exhibited cohesive failure in 62.5 % of tests



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Calculation of energy required for failure(neglecting damping, rebound energy)

• Energy per impact = pendulum swing x Force

• Total energy = number of impacts x energy per impact


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(1) Impact-induced coating failure is a statistical process (2) tests are sensitive to small changes in deposition conditions

Diamond-like carbon coatings deposited at higher power have...• shorter time-to-failure• lower energy-to-failure• high probability of cohesive failure• incomplete removal (final depth is lower than thickness)

How does the impact performance of DLC compare to other brittle materials?

Summary


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Fatigue performance of these DLC coatings is worse than FS and Si!

(DLC is in highly stressed state)

much higher load necessary for failure


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To summarise….

1. Nanoindentation techniques are essential in the optimisation of the mechanical properties of thin films and coatings

2. The NanoTest has large range of testing techniques, and thereforeoffers a complete testing capability

3. These techniques are possible due to the unique pendulum design

4. The high temperature option and impact module allow testing undercontact conditions that can closely simulate those in service

5. The versatility and wide range of options have resulted in the systemfinding applications in….

Bringing nanomechanicalmeasurements into the real-world


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• Automotive• Bearings• Biomedical Devices• Ceramics• Composites• Contact Lenses• Cutting Tools• Hard Coatings• Laminates• Magnetic Disks• Microelectronics• Nanocomposites• Optical Coatings

• Optical Disks• Packaging Materials• Paints• Paper Coatings• Pharmaceuticals• Photographic Film• Polymers• Powders• Printing Plates• Semiconductors• Thin Film Adhesion• Turbine Blades• Ultra-thin films

Current NanoTest application areas include…

...future application areas will be in?

recent developments in nanoscale mechanical property testing high temperature testing and impact...

Documents

high temperature testing

impact testing contact

dynamic hardness testing

s impact slide

issue slide

impact testing dr krish

realworld slide

increasing temperature