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MICRO
MATERIALS
MEASURING NAN OTEC HNOL OGY
Introduction to Nano-scale
Mechanical Properties Testing
Micro Materials Ltd. Wrexham, UK.
MICRO
MATERIALS
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Outline
• Depth-sensing indentation
• The NanoTest system
• Case studies
• Nanoindentation – bond pads
• Nano-impact – fatigue of DLC films
• Polymer nanoindentation
• Summary
MICRO
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What is depth-sensing indentation?
loading
• elastic and plastic properties
of the sample determine the
shape of the unloading curve
unloading
coating
substrate
• force, displacement and time are recorded
throughout the indentation of a test sample
by a diamond probe
Scanning = transverse sample movement during loading
Impact = sample oscillation at constant load
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Where does depth-sensing indentation fit in?
SPM
Nanoindentation
Macro-hardness
• Surface
• Surface/nearsurface
• Bulk
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Friction
Adhesion (local)
(Wear)
Topography
Role of specific
chemical
interactions?
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Mechanical
properties of thin
films and coatings
Hardness
Modulus
Creep
Depth-profiling
Wear resistance
Interfacial adhesion
Fracture toughness
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Hardness of thick
coatings and bulk
materials
Fracture toughness
of bulk materials
MICRO
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Micro Materials Limited growing market share in a fast growing market...
Source: British Library on-line database. Keyword search on “nanoindentation”.
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The most versatile
nanomechanical
property testing centre...
The NanoTest system
2 loading heads:
Nano -
10 mN - 500 mN
Micro - 0.1 N - 20 N
3 modules:
10 options including:
Indentation
Scanning
Impact
High temp testing
Continuous compliance
Pin-on-disk wear
Microscopes
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The NanoTest pendulum
Advantages of the
pendulum over vertical
loading instruments
include…
• large samples possible
• calibrated contact load
• high temperature stage
• sample oscillation
• options such as pin-ondisk wear testing and 2D
levelling stage
Original design - University of Lancaster, UK, Newey, Wilkins and Pollock, J Phys E, 1982, pp119-122.
Micro Materials formed 1988 by Dr Jim Smith, first instruments sold 1992.
MICRO
MATERIALS
Indentation
MEASURING NAN OTEC HNOL OGY
Quantitative measurement of the
mechanical properties of thin films
Comparison of load ranges
Technique
SPM
NanoTest
MicroTest
Hardness
Applied Force
nN-mN
10 mN-500 mN
100 mN - 20 N
N-kN
nickel plating
passivation layer
Si wafer
Al pad
Aim: determine the hardness and modulus of top
layer in IC bond pad without substrate influence
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Indentation
MEASURING NAN OTEC HNOL OGY
NanoTest indentation module
Techniques
• Nanoindentation
• Microindentation
• Load-partial-unload
• High temperature testing
• Continuous compliance
Properties
• Hardness
• Elastic modulus
• Fracture toughness
• Adhesion
• Creep
• Elastic and plastic work
• Elastic recovery parameter
• Stress-strain
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Indentation
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Indentation
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Depth-profiling of mechanical property variation
Load-partial-unload
technique
20-cycle load-partial-unload
Depth controlled 50-1000 nm
Experiment time 30 min
Analysis time 30 sec
• rapid and quantified
variation in hardness
and modulus with depth
MICRO
MATERIALS
Indentation
MEASURING NAN OTEC HNOL OGY
Hardness of 5 mm Ni-based top-layer of bond pad
coating
constant
hardness
coating
+ substrate
coating
+ substrate
decreasing
hardness
• “1/10 rule” - for a hard coating on softer substrate
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How homogeneous is my
coating?
An example of nanoindentation
as a QA tool
• rapid, automatic scheduling
of arrays of indentations
Indentation
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Indentation
MEASURING NAN OTEC HNOL OGY
Mapping variations in hardness and elasticity at the nanoscale
Precise indent placement with
a 4-objective high resolution
metallurgical microscope
Indentations along 10 mm alloy interface
between stainless steel surfaces
NOTE: 1 objective can be
replaced by contact/AC mode SPM
• studies of nano- and micro- scale phase separation
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Indentation
MEASURING NAN OTEC HNOL OGY
Nanoindentation-induced adhesion failure
DLC on Si
Adhesion failure
• indentation + residual stress = coating failure
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NanoTest scanning module
for…
• Scratch testing
• Nano- and micro- friction
• Adhesion
• Profilometry
• Acoustic Emission
• Fatigue wear
“Nanotribometer”
Scanning
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Ramped load scratch testing (1)
Film failure at critical
normal load Lc is
revealed by...
• Depth change
• Acoustic Emission
• Friction Force
• Topography Scan
• Optical Microscopy
Adhesion failure at critical load of 3.2 mN
Scanning
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Scanning
MEASURING NAN OTEC HNOL OGY
Ramped load scratch testing (2)
• qualitative ranking of test coatings and multilayers at the development stage
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Scanning
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Multi-pass sub-critical load scratch testing
2, 4, 6
dplast
1, 3, 5, 7
Experimental parameters:
25 mm Rockwell probe
scratch load:- ramped to 1 mN
topography load 0.1 mN
scan speed 0.5 mm/s
dtotal
Nano-scratching wear of polymer film
Repeat scratches over the same wear track reveal...
• fatigue behaviour
• cohesive failure (fracture)
• adhesive failure (delamination)
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Impact
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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
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Impact
MEASURING NAN OTEC HNOL OGY
Impact testing - simulating fatigue wear and failure
• adhesion failure
• fracture
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Impact
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Impact Testing of a brittle TiN coating
100 mN applied load is
on throughout test
80 Hz oscillation frequency
Oscillation on 30 s after start
Oscillation off 30 s before end
Film failure after 250 s
• 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
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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 therefore
offers 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 under
contact conditions that can closely simulate those in service
5. The versatility and wide range of options have resulted in the system
finding applications in….
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NanoTest systems are in regular use in…
MIT USA
Eastman Kodak USA
Philips Netherlands
HP Singapore
Gintic Singapore
Cambridge Uni UK
Barcelona Uni Spain
VITO Belgium
NPL UK
Enterprise Ireland
Salford Uni UK
Cranfield Uni UK
Timken USA
RPI NY USA
AGFA DE
LOT Oriel DE
Paisley UK
Loughborough UK
TU Clausthal DE
UMIST UK
DERA UK
Leeds Uni UK
ICM Madrid Spain
Trivandrum India
...and many more - over 75 sites worldwide
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Current NanoTest application areas include…
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Automotive
Bearings
Biomedical Devices
Ceramics
Composites
Contact Lenses
Cutting Tools
Hard Coatings
Laminates
Magnetic Disks
Microelectronics
Optical Coatings
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Optical Disks
Packaging Materials
Paints
Paper Coatings
Pharmaceuticals
Photographic Film
Polymers
Powders
Printing Plates
Semiconductors
Thin Film Adhesion
Turbine Blades
...future application areas will be in?