Electrical and mechanical behaviour of metal thin films with deformation-induced cracks predicted by computational homogenisation

Kaiser, Tobias; Cordill, Megan J.; Kirchlechner, Christoph; Menzel, Andreas

doi:10.1007/s10704-021-00582-3

Cited by 9 publications

(7 citation statements)

References 45 publications

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“…Indeed, we see a progressive increase in the quantity and size of cracks as the loading fraction is increased. Hence, the decrease in electrical conductivity with increase in wt.% SiC loading can directly be attributed to film cracking due to the loss of conductive pathways [67,68]. The silver IDEs were screen printed onto the polyimide substrate as previously described, and the SiC inks were then screen printed atop the silver IDEs to fabricate the thermistors, as described in Section 2.3 and Figure 2.…”

Section: Printed Sic Thermistor Characterizationmentioning

confidence: 99%

All Screen Printed and Flexible Silicon Carbide NTC Thermistors for Temperature Sensing Applications

Wadhwa,

Benavides-Guerrero,

Gratuze

et al. 2024

Materials

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In this study, Silicon Carbide (SiC) nanoparticle-based serigraphic printing inks were formulated to fabricate highly sensitive and wide temperature range printed thermistors. Inter-digitated electrodes (IDEs) were screen printed onto Kapton® substrate using commercially avaiable silver ink. Thermistor inks with different weight ratios of SiC nanoparticles were printed atop the IDE structures to form fully printed thermistors. The thermistors were tested over a wide temperature range form 25 °C to 170 °C, exhibiting excellent repeatability and stability over 15 h of continuous operation. Optimal device performance was achieved with 30 wt.% SiC-polyimide ink. We report highly sensitive devices with a TCR of −0.556%/°C, a thermal coefficient of 502 K (β-index) and an activation energy of 0.08 eV. Further, the thermistor demonstrates an accuracy of ±1.35 °C, which is well within the range offered by commercially available high sensitivity thermistors. SiC thermistors exhibit a small 6.5% drift due to changes in relative humidity between 10 and 90%RH and a 4.2% drift in baseline resistance after 100 cycles of aggressive bend testing at a 40° angle. The use of commercially available low-cost materials, simplicity of design and fabrication techniques coupled with the chemical inertness of the Kapton® substrate and SiC nanoparticles paves the way to use all-printed SiC thermistors towards a wide range of applications where temperature monitoring is vital for optimal system performance.

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Section: Printed Sic Thermistor Characterizationmentioning

confidence: 99%

All Screen Printed and Flexible Silicon Carbide NTC Thermistors for Temperature Sensing Applications

Wadhwa,

Benavides-Guerrero,

Gratuze

et al. 2024

Materials

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“…Unlike metal thin films, composite metalpolymer inks do not experience sudden rupture [24][25][26][27][28][29][30][31][32] or fatigue failure [9,10,33] at low tensile strain levels (<10%) while deposited on compliant (polymer) substrates. Therefore, composite inks are able to maintain electrical conductivity at higher applied strains provided they are deposited on an adequately stiff polymer substrate [23,34,35].…”

Section: Introductionmentioning

confidence: 99%

Applicability of normalized resistance rate model for predicting fatigue life and resistance evolution in composite conductive inks

Li,

Pierron,

Antoniou

2024

Flex. Print. Electron.

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The electrical resistance of metal-polymer conductive inks increases as they undergo cyclic loading, posing a major challenge to their reliability as interconnect materials for flexible electronic devices. To characterize an ink’s fatigue performance, extensive electro-mechanical testing is usually performed. Phenomenological models that can accurately predict the resistance increase with cyclic loading can save time and be useful in flexible conductor design against fatigue failure. One such model was recently developed for only one composite ink type. The model is based on experiments monitoring resistance under monotonic stretch data and multiple experiments measuring the rate of increase of the resistance under different strain amplitudes and mean strains. The current work examines whether such resistance rate model could be generalized to apply for more types of composite inks. Two composite inks with different binder material, metal flake sizes and shapes, and substrate material were experimentally tested under monotonic and cyclic loading. It was found that the two new inks are also more sensitive to strain amplitude than mean strain. The resistance rate model accurately predicts early/catastrophic failure (<1000 cycles) in all inks and conservatively estimates fatigue life for low strain amplitudes. A protocol detailing the procedures for applying the resistance model to new inks was outlined.

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“…The present contribution focuses on the characterisation of damage in ductile materials through electrical measurements. Changes in electrical conductivity can result from geometrical contributions and the underlying microstructure, for example, cracks [12,13] or dislocations [14,15]. In order to distinguish the individual effects of geometry change and microstructure, an electro-mechanically coupled framework, which considers the effect of plasticity and damage on electrical quantities, is established.…”

Section: Introductionmentioning

confidence: 99%

Characterisation of damage by means of electrical measurements: Numerical predictions

Güzel,

Kaiser,

Lücker

et al. 2023

Proc Appl Math and Mech

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Understanding damage mechanisms and quantifying damage is important in order to optimise structures and to increase their reliability. To achieve this goal, experimental‐ and simulation‐based techniques are to be combined. Different methods exist for the analysis of damage phenomena such as fracture mechanics, phase field models, cohesive zone formulations and continuum damage modelling. Assuming a typical ‐type damage formulation, the governing equations of continua that account for gradient‐enhanced ductile damage under mechanical and electrical loads are derived. The mechanical and electrical sub‐problems give rise to the local form of the balance equation of linear momentum, the micromorphic balance relation and the continuity equation for the electric charge, respectively. Experimental investigations indicate that changes in electrical conductivity arise due to the evolution of the underlying microstructure, for example, of cracks and dislocations. Therefore, motivated by deformation‐induced property changes, the effective electrical conductivity is assumed to be a function of the damage variable. This eventually allows the prediction of experimentally recorded changes in the electrical resistance due to mechanically‐induced damage processes. Interpreting the resistivity as a fingerprint of the material microstructure, the simulation approach proposed in the present work contributes to the development of non‐destructive electrical‐resistance‐based characterisation methods. To demonstrate the applicability of the proposed framework, different representative simulations are studied.

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Electrical and mechanical behaviour of metal thin films with deformation-induced cracks predicted by computational homogenisation

Cited by 9 publications

References 45 publications

All Screen Printed and Flexible Silicon Carbide NTC Thermistors for Temperature Sensing Applications

All Screen Printed and Flexible Silicon Carbide NTC Thermistors for Temperature Sensing Applications

Applicability of normalized resistance rate model for predicting fatigue life and resistance evolution in composite conductive inks

Characterisation of damage by means of electrical measurements: Numerical predictions

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