Lifetime modelling and geometry optimization of meander tracks in stretchable electronics

Grams, Arian; Kuttler, Simon; Löher, Thomas; Walter, H.; Wittier, O.; Lang, Klaus‐Dieter

doi:10.1109/eurosime.2018.8369887

Cited by 3 publications

(9 citation statements)

References 8 publications

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“…The results of the Coffin–Manson equations for samples with textile structures with the failure criterion of Rmax = 1 kΩ are shown in Figure 11. To compare the lifetime, the life expectancy of a sample with meandering copper tracks is added [26].…”

Section: Resultsmentioning

confidence: 99%

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Investigation of the Mechanical and Electrical Properties of Elastic Textile/Polymer Composites for Stretchable Electronics at Quasi-Static or Cyclic Mechanical Loads

et al. 2019

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In the last decade, interest in stretchable electronic systems that can be bent or shaped three-dimensionally has increased. The application of these systems is that they differentiate between two states and derive there from the requirements for the materials used: once formed, but static or permanently flexible. For this purpose, new materials that exceed the limited mechanical properties of thin metal layers as the typical printed circuit board conductor materials have recently gained the interest of research. In this work, novel electrically conductive textiles were used as conductor materials for stretchable circuit boards. Three different fabrics (woven, knitted and nonwoven) made of silver-plated polyamide fibers were investigated for their mechanical and electrical behavior under quasi-static and cyclic mechanical loads with simultaneous monitoring of the electrical resistance. Thereto, the electrically conductive textiles were embedded into a thermoplastic polyurethane dielectric matrix and structured by laser cutting into stretchable conductors. Based on the characterization of the mechanical and electrical material behavior, a life expectancy was derived. The results are compared with previously investigated stretchable circuit boards based on thermoplastic elastomer and meander-shaped conductor tracks made of copper foils. The microstructural changes in the material caused by the applied mechanical loads were analyzed and are discussed in detail to provide a deep understanding of failure mechanisms.

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Section: Resultsmentioning

confidence: 99%

“…Life expectancy for elastic textile/polymer composites with conductors made of silver-plated woven or knitted textiles (R max = 1 kΩ) compared with samples made of meandering copper tracks [26]. …”

Section: Figurementioning

confidence: 99%

Investigation of the Mechanical and Electrical Properties of Elastic Textile/Polymer Composites for Stretchable Electronics at Quasi-Static or Cyclic Mechanical Loads

et al. 2019

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“…Larger deformations without tearing up can be reached by meandering designs of the interconnects, which elongate like two-dimensional springs [1,2,8]. Generally, the weakest points of the interconnections and the vulnerability of the stretchable system are the tips of the meanders and the area close to the rigid component on the deformable substrate, where stresses concentrate [1,2,6,8]. In this study, the area close to the rigid component is called a transition area.…”

Section: Stretchable Electronics Based On Structured Copper Foilmentioning

confidence: 97%

“…Conventional printed circuit board (PCB) manufacturing and component assembly are well-established and can be adapted for stretchable electronics fabrication. For example, copper-etching, soldering, and other related process steps are used in stretchable circuit board (SCB) fabrication, developed by Fraunhofer IZM and TU Berlin (Germany), where rigid substrates (glass-reinforced epoxy laminate FR4 boards) are replaced by stretchable thermoplastic polyurethane (TPU) film [1,2,6,8]. Contrasting the rigid and flexible PCBs, the electronic system is stretchable on the TPU carrier and components are connected by meandering copper tracks [1,2].…”

Section: Stretchable Electronics Based On Structured Copper Foilmentioning

confidence: 99%

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Mechanical properties of structured copper and printed silver hybrid stretchable electronic systems

Salo

Werft

Adams

et al. 2023

Flex. Print. Electron.

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Stretchable electronics can be realized using different manufacturing methods and hybrids thereof. An example of the latter is the combination of stretchable circuit boards with screen-printing, which will be discussed in this work. The hybrid stretchable electronics structures are based on photolithographically structured and rigid copper islands and screen-printed silver ink interconnections. This enables the assembly of components with a high number of contacts onto the copper islands and deformable silver ink lines between islands. The transition area between islands and lines is critical due to local stress concentration. The effect and potential mitigations were studied by measuring the electrical resistance of test interconnections under mechanical loading. The first set of samples was elongated up to 30 % in tensile tests. The second set of samples was elongated 10 %, 20 %, and 30 % in cyclic tests up to 10.000 cycles. After the tests, extensive failure analysis, e.g., scanning electron microscope, and finite element analysis were conducted.In tensile tests at maximum load, the interconnections either snap apart or their resistance increases by 640 % in the transition area. Adding protective structures around the transition area, the resistance increase can be reduced to 12 %. Stress concentration in the transition area can be controlled with the layout of the structures, as shown in the cyclic tests. Depending on a layout, the structures protect interconnections in the transition area (resistance < 4 Ω at 10 % and 20 % throughout 10.000 cycles, and up to 5000 cycles at 30 % elongation), or with particular designs, cause fatal damage of the circuitry and fail early. The identified failure mechanism is typically fatigue damage caused by the repeated bending of the protective structure. The observed resistance increase at the interface was closely related to the crack propagation phase in the protective structures.

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Determination of relevant material behavior for use in stretchable electronics

Walter

Grams

Seckel

et al. 2018

2018 19th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and

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Lifetime modelling and geometry optimization of meander tracks in stretchable electronics

Cited by 3 publications

References 8 publications

Investigation of the Mechanical and Electrical Properties of Elastic Textile/Polymer Composites for Stretchable Electronics at Quasi-Static or Cyclic Mechanical Loads

Investigation of the Mechanical and Electrical Properties of Elastic Textile/Polymer Composites for Stretchable Electronics at Quasi-Static or Cyclic Mechanical Loads

Mechanical properties of structured copper and printed silver hybrid stretchable electronic systems

Determination of relevant material behavior for use in stretchable electronics

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