Fracture and Delamination of Chromium Thin Films on Polymer Substrates

Cordill, Megan J.; Taylor, Aidan A.; Schalko, J.; Dehm, Gerhard

doi:10.1007/s11661-009-9988-9

Cited by 79 publications

(57 citation statements)

References 30 publications

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“…However, numerous studies have shown that thin film coatings on ductile substrates will fracture at low strains. Examples of thin films with low fracture strain of less than 1% include SiO 2 on various polymer substrates [1,2], Chromium (Cr) on polyimide [3], Ta on polyimide [4], and diamond-like carbon (DLC) on stainless steel [5], with the exact fracture values dependent on film thicknesses.…”

Section: Introductionmentioning

confidence: 99%

In situ Study of Cracking and Buckling of Chromium Films on PET Substrates

Jin

Cordill

et al. 2010

Exp Mech

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Chromium (Cr) films are widely used as interlayers to promote the adhesion of copper or gold to substrates. However, the Cr interlayer usually fractures at lower strains than the ductile metal films. In this paper, the cracking and buckling behavior of Cr films on polyethylene terephthalate (PET) substrates were studied in situ under tensile loading with the Atomic Force Microscope (AFM) and optical microscope imaging. Cr films with three nominal thicknesses of 15, 70 and 140 nm were studied. The depth and width of the cracks, as well as the height and width of the buckles, were measured from AFM images acquired at incremental loading steps. The buckle shapes at different strain levels were carefully examined using AFM line profile. It was found that at large strain levels the measured buckle shapes usually deviated from the elastic buckling mode shapes. Further in situ AFM imaging of the buckles at a smaller scan area revealed that in some cases the buckles were cracked at the apex. These in situ nanoscale measurements provided experimental observations and data for further model development and more accurate measurement of the interfacial fracture energy at the Cr-PET interface.

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Section: Introductionmentioning

confidence: 99%

In situ Study of Cracking and Buckling of Chromium Films on PET Substrates

Jin

Cordill

et al. 2010

Exp Mech

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“…These undergo multiple failure mechanisms such as delamination [4], channel cracking [5,6] and surface cracking which can be coupled with time-dependent damage from load cycling [7] and environmental degradation [8]. While multiple techniques and analyses exist for studying delamination or channel cracking of deposited thin films, direct measurements of fracture toughness values are relatively rare.…”

Section: Introductionmentioning

confidence: 99%

In-Situ Measurements of Free-Standing, Ultra-Thin Film Cracking in Bending

et al. 2015

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Metallic thin films are widely used and relied upon for various technologies. Direct measurements of fracture toughness are rare for metallic thin films and existing methods for obtaining these measurements often do not provide characterization of the cracking process for determination of crack growth mechanisms. To rectify this, we explore a new technique which utilizes doubly clamped, in-situ three-point bend testing of micro-scale and nano-scale specimens. This is done by in-situ scanning electron microscopy (SEM) and transmission electron microscopy (TEM) mechanical testing for specimens with thicknesses of 2500 nm (SEM), 500 nm (SEM) and 100 nm (TEM). For in-situ TEM, a novel notching method is employed using the converged electron beam which achieves a notch radius of approximately 5 nm. Additionally, we present supporting characterization using Electron Backscatter Diffraction (EBSD) for 2500 nm thick specimens as a demonstration of the potential of this technique for understanding local deformation. Analysis of the acquired data presents several issues that require addressing, and recommendations for future improvements are given.

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“…[6]). Experimentally, a large volume of work has been carried out on the failure behaviour of coating layers of a wide range of properties on a variety of substrates, mainly metallic [7][8][9] and polymeric [10][11][12][13][14][15][16]. The failure of these coatings has been observed by optical microscopy, electron microscopy [17,18] and electrical resistance measurements [19][20][21], and the mechanics of crack initiation and propagation in a coating/substrate system are well understood [5,22].…”

Section: Introductionmentioning

confidence: 99%

Modelling the effect of temperature on crack onset strain of brittle coatings on polymer substrates

et al. 2011

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The effect of temperature on the crack onset strain (COS) of brittle coatings on polymer substrates was investigated through a series of temperature-controlled tensile tests carried out in situ under an optical microscope. It was observed that the failure of such materials under tensile strain was strongly affected by temperature, but the exact behaviour was heavily dependent upon the type of material used. Below the glass transition temperature, T g , of the polymer substrate, an increase in temperature led to a decrease in crack onset strain. Above the T g , the substrate softening effects and corresponding shrinkage behaviour had a presiding role, leading to an increase in COS at elevated temperatures. The experimental COS data were modelled as a linear superposition of an intrinsic COS and the internal strain taking into consideration the respective influences of temperature dependent energy release rate for crack propagation and thermal expansion behaviour. Using adjustable values of the coefficient of thermal expansion and toughness of the coating, the model was found to accurately reproduce the change of COS with temperature of two different coatings on aromatic polyester substrates. The proposed approach enables, for any thin film composite with known material properties, the COS at any given temperature to be predicted.

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Fracture and Delamination of Chromium Thin Films on Polymer Substrates

Cited by 79 publications

References 30 publications

In situ Study of Cracking and Buckling of Chromium Films on PET Substrates

In situ Study of Cracking and Buckling of Chromium Films on PET Substrates

In-Situ Measurements of Free-Standing, Ultra-Thin Film Cracking in Bending

Modelling the effect of temperature on crack onset strain of brittle coatings on polymer substrates

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