Bending Fatigue Behavior of Ag Nanowire/Cu Thin-Film Hybrid Interconnects for Wearable Electronics

Abstract

Enhancing the mechanical reliability of metal interconnects is important for achieving highly reliable flexible/wearable electronic devices. In this study, Ag nanowire and Cu thin-film hybrid interconnects were explored as a novel concept to enhance mechanical reliability under bending fatigue. Bending fatigue tests were conducted on the Cu thin films and Cu/Ag nanowire/polyimide (CAP) interconnects. The increase in resistance was larger for the Cu thin films than for the CAP. The single-component Cu electrodes showed multiple crack initiation and propagation due to bending strain, which degraded the electrical conductivity. In CAP, however, no long-range cracks were observed, even after 300,000 cycles of bending, although a wavy structure was observed, probably due to the delamination of the Ag nanowires under repeated bending. Our study confirms that flexible Ag nanowire and metal thin-film hybrids can enhance the mechanical reliability of metal thin-film interconnects under bending fatigue.

Introductory Overview of Layer Formation Techniques of Ag Nanowires on Flexible Polymeric Substrates

“…The scarcity and cost fluctuations of indium, along with environmental concerns related to its extraction, challenge its long-term viability. Additionally, the adaptability of ITO to emerging technologies is limited by its brittleness, which reduces its durability, especially on flexible substrates, and its low conductivity at lower thicknesses [1][2][3][4][5][6][7][8]. As a result, there is increasing demand for electronic components that offer not only high performance but also environmental sustainability.…”

Versatile Applications of Silver Nanowire-Based Electrodes and Their Impacts

“…Hence, in recent years, there has been significant research interest in developing alternative transparent electrode materials. One promising candidate is silver nanowires (AgNWs) [ 9 , 10 , 11 ]. In this review paper, we discuss the current state of research on AgNW transparent electrodes, including their synthesis, properties, and potential applications.…”

Review of the Versatile Patterning Methods of Ag Nanowire Electrodes

“…However, ITO is intrinsically brittle, which makes its use challenging in flexible or wearable devices. As alternatives to ITO, therefore, carbon-based materials such as graphene or carbon nanotubes (CNTs), or metal-based networks such as metal meshes or metal nanowires, are actively being studied for transparent electrodes [13][14][15]. In particular, Ag nanowire networks have shown superior properties, especially in optical transmittance and electrical conductivity [16][17][18][19][20][21].…”