Characterization of Bending, Crease, Aging, and Immersion Effects on Flexible Screen-Printed Silver Traces

Sondhi, Kartik; Avuthu, Sai Guruva Reddy; Richstein, Jorg; Fan, Z. Hugh; Nishida, Toshikazu

doi:10.1109/tcpmt.2019.2944349

Cited by 3 publications

(3 citation statements)

References 34 publications

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“…In figures 7(c) and (d), a higher change of resistance is observed for a lower bending radii. In another application, the effect of bending radii induced stress on flexible conducting traces was observed in a previous study published by our group [35]. It can also be observed from figures 7(c) and (d) that a higher substrate thickness/via lengths causes a higher change in resistance.…”

Section: Cyclic Resistance Measurementssupporting

confidence: 63%

“…As reported by Hicks et al [34], cyclic bending causes a prolonged interfacial stress and can lead to formation of cracks within the via and subsequent crack propagation on interfaces [35]. In the aforementioned study, completely filled vias were used.…”

Section: Cyclic Resistance Measurementsmentioning

confidence: 93%

“…As indicated computationally, there is a higher stress concentration at the junction of the metal trace and 50 µm via. The higher stress may lead to micro-cracks [35]. Hence, with cycling, the 50 µm via would incur a larger increase in resistance compared to the 450 µm via as seen in figure 5(e).…”

Section: Cyclic Resistance Measurementsmentioning

confidence: 99%

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Fabrication and non-destructive characterization of through-plastic-via (TPV) in flexible hybrid electronics

Sondhi

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Flex. Print. Electron.

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Flexible hybrid electronics (FHE) have been gaining interest in recent years as this technology has the potential to become a low-cost, mechanically pliable sister technology for multilayer printed circuit boards (PCBs). One of the limitations of rigid PCB is low endurance to mechanical bending, this limitation poses a threat to the efficacy for wearable applications. During bending, a substrate experiences both compressive and tensile stress. These stresses are similar in magnitude but opposite in direction. This difference in directionality creates a non-linear stress gradient in a via which impacts the structural integrity, endurance and bending reliability of a circuit during its operation. Additionally, as flexible substrates can be bent to a higher bending radius, the magnitude of maximum extrinsic stresses observed on flexible substrates could be higher than the stress observed on rigid substrates. Hence, the reliability and mechanical compliance of through-hole-plastic-vias for reliable flexible circuits need to be understood. In this study, we have developed a process to create vias on flexible substrates using a rapid commercial laser (Nd-YaG laser) to study the effects on via resistance due to three different variables—bending stresses, via diameter and via length. A novel non-destructive approach (CT-scanner) was used to scan the via structures and determine the filling for all via diameters from 50 to 450 µm and via lengths of 7, 10 mils. Two different configurations of vias were used to measure and analyze the effect of mechanical cycling on via resistance and via filling. This demonstration of electrical and mechanical testing of vias and novel methodologies for via filling, and via electrical resistance can contribute to better design and fabrication guidelines of multi-layer FHE circuits.

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Section: Cyclic Resistance Measurementssupporting

confidence: 63%

Section: Cyclic Resistance Measurementsmentioning

confidence: 93%

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Fabrication and non-destructive characterization of through-plastic-via (TPV) in flexible hybrid electronics

Sondhi

Avuthu

Richstein

et al. 2021

Flex. Print. Electron.

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Incorporating a Novel Hexaazatriphenylene Derivative to a Flexible Screen-Printed Electrochemical Sensor for Copper Ion Detection in Water Samples

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Mandrel Bend Test of Screen-Printed Silver Conductors

Chen

Chow

Zhou

et al. 2023

Journal of Electronic Packaging

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Flexible electronics are electronic devices and components that can be stretched, bent, twisted, and folded without losing their functionality. Flexible electronics is conformable, lightweight, easily tailorable, and low-cost, and thus, flexible electronics is increasingly being explored in health care, internet of things, automotive, aerospace, communication, safety, security, and food-related applications. Also, flexible electronics can now support increased functionality as well as various fabrication techniques. With an increased adaptation of flexible electronics, research is being conducted to better understand the failure mechanism of flexible electronics and thus improve their reliability and service life. In this paper, a cyclic mandrel bend test has been designed and carried out on printed conductors with PET and PI substrates. With the designed test apparatus, both tensile and compressive bend tests have been performed. Using a 4-wire method, the resistance change of the printed conductors with different widths has been measured in-situ under tensile and compressive loading conditions using mandrels with different radii. The results have been compared among different conductor widths, bending modes, and substrate materials. Besides, in-situ SEM images have been taken to understand the failure mechanisms of the printed conductors. Based on the study, it is seen that there exists a direct correlation between the mandrel diameter, the damage in the printed conductor, and thus, the resistance change with cyclic mandrel testing. Also, it is seen that the damage under compressive bending mode is significantly lower than the damage under tensile bending mode.

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Characterization of Bending, Crease, Aging, and Immersion Effects on Flexible Screen-Printed Silver Traces

Cited by 3 publications

References 34 publications

Fabrication and non-destructive characterization of through-plastic-via (TPV) in flexible hybrid electronics

Fabrication and non-destructive characterization of through-plastic-via (TPV) in flexible hybrid electronics

Incorporating a Novel Hexaazatriphenylene Derivative to a Flexible Screen-Printed Electrochemical Sensor for Copper Ion Detection in Water Samples

Mandrel Bend Test of Screen-Printed Silver Conductors

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