Stretchable copper interconnects with three-dimensional coiled structures

Abstract

We propose a new scheme of stretchable metal interconnects utilizing the electroplated three-dimensional (3D) coil structure, as a strategy for improving the stretching performance of spring-like electrodes through the suppression of local stress concentration. In this process, the 3D copper coils are fabricated by a multi-step electroplating process, and embedded within an elastomeric substrate forming stretchable configuration. By comparing the stretching behavior of the two-dimensional and 3D coils under static or cyclic deformation, the beneficial effects of the 3D configuration have been demonstrated. The present technique can be regarded as an effective way to enhance the stability of interconnects under cyclic deformation significantly, while maintaining the high mechanical strength and electrical conductivity of electroplated electrodes.

An Omnidirectionally Stretchable Piezoelectric Nanogenerator Based on Hybrid Nanofibers and Carbon Electrodes for Multimodal Straining and Human Kinematics Energy Harvesting

“…Since the electrode has a slight decrease in the output after 9000 stretching cycles due to degradation of electrodes, an improvement in the mechanical durability of the carbon electrode is still needed by developing alternative binder materials and optimizing coating conditions. By contrast, the porous web of randomly aligned nanofibers suspended between the two electrodes is subjected to direct deformation upon applied strain, resulting in dipole generation due to their high piezoelectricity, while the porous morphology provides high stability under stretching . The nanofiber mat remains suspended between the two electrodes on the 3D micropatterned substrate, which enables it to directly absorb the applied strain, thus avoiding any loss through dissipation by the stretchable substrate.…”

Engineering the Charge Transport of Ag Nanocrystals for Highly Accurate, Wearable Temperature Sensors through All-Solution Processes

“…To date, there have been many studies concerning the elimination of external strain in flexible devices. Such methods include fabricating the devices at the neutral mechanical plane (NMP), integrating both temperature and strain sensors on the same platform, and using free‐form wavy geometrical designs of metals . While these are efficient methods to exclude strain, limitations still exist: The NMP cannot cancel out strain coming from dextral movement, and single‐platform strain and temperature sensors still show some variation as temperature sensors are affected by external strain and strain sensors are affected by external temperature.…”

Hybrid‐type stretchable interconnects with double‐layered liquid metal‐on‐polyimide serpentine structure

“…In many approaches for fabricating stretchable electronic circuits [1][2][3][4][5][6], the overall stretchability is provided by stretchable interconnecting regions, while active devices vulnerable to even a small amount of mechanical deformation, such as thin-film transistors [1,2], sensors [3,4], or light-emitting devices [5,6], are located within rigid islands. For achieving stretchable interconnects, various strategies have been employed [7][8][9][10][11][12][13][14]. For example, nonstretchable metal thin films can be configured as stretchable shapes such as serpentine [7,8], wavy [9,10], or coiled structures [11], which can accommodate the tensile strain via structural transformation.…”

“…For achieving stretchable interconnects, various strategies have been employed [7][8][9][10][11][12][13][14]. For example, nonstretchable metal thin films can be configured as stretchable shapes such as serpentine [7,8], wavy [9,10], or coiled structures [11], which can accommodate the tensile strain via structural transformation. It is also possible to use intrinsically stretchable conductors as interconnecting materials, where metal or carbon-based conductive fillers are dispersed within an elastomeric matrix [12][13][14].…”