Stretching-induced interconnect delamination in stretchable electronic circuits

Abstract

Abstract. Stretchable electronics offer increased design freedom of electronic products. Typically, small rigid semiconductor islands are interconnected with thin metal conductor lines on top of, or encapsulated in, a highly compliant substrate, such as a rubber material. A key requirement is large stretchability, i.e. the ability to withstand large deformations during usage without any loss of functionality. Stretching induced delamination is one of the major failure modes that determines the amount of stretchability that can be achieved for a given interconnect design. During peel testing, performed to characterize the interface behaviour, the rubber is severely lifted at the delamination front while at the same time fibrillation of the rubber at the peel front is observed by ESEM analyses. The interface properties are established by combining the results of numerical simulations and peeling experiments at two distinct scales: the global force-displacement curves and local rubber lift geometries. The thus quantified parameters are used to predict the delamination behaviour of zigzag and horseshoe patterned interconnect structures. The accuracy of these finite element simulations is assessed by a comparison of the calculated evolution of the shape of the interconnect structures and the fibrillation areas during stretching with experimental results obtained by detailed in-situ analyses.

Analysis of the dissipative mechanisms in metal–elastomer interfaces

“…As a result, the structural dissipation due to plastic deformation of the copper film, Γ str , is directly incorporated. For the PDMS, a Neo-Hookean model with C 10 = 0.165 MPa is identified from the uniaxial data (figure A.5), similarly as is used by van der Sluis et al (2011a). Hoefnagels et al (2010) observed a fibrillation mechanism at the peel front.…”

Bifurcation Analysis Versus Maximum Force Criteria in Formability Limit Assessment of Stretched Metal Sheets

“…These FLDs apply to copper foils described by rigid-plastic constitutive equations (or elasto-plastic models with h/E 1). The material parameters corresponding to four hardening models (i.e., linear, Hollomon, Swift and Voce laws) have been identified using a UT experiment provided in van der Sluis et al [2011], and the relevant values of these parameters are reported in Fig. 4.…”

High‐Adhesion Stretchable Electrodes Based on Nanopile Interlocking

“…[64] As a proof of concept, we demonstrate that the stretchable electrode can be used to detect EMG signals and that the stretchable strain sensor can be utilized to simultaneously monitor the deformation induced by the elbow bending. [50][51][52][53][54][55][56][57][58][59][60][61] Adhesion is crucial for the long-term use of stretchable electronics, such as the detection of body-surface biosignals in electromyography (EMG) and electrocardiography (ECG), and implanted devices where the interface friction may easily induce failures of debonding. It also opens up for exploration of the advanced property-function relationships combining high adhesion and stretchability.…”

“…[50][51][52][53][54][55][56][57][58][59][60][61] Adhesion is crucial for the long-term use of stretchable electronics, such as the detection of body-surface biosignals in electromyography (EMG) and electrocardiography (ECG), and implanted devices where the interface friction may easily induce failures of debonding. This is due to the huge difference in physical and chemical properties (e.g., Young's modulus: tens of GPa for gold while only several MPa for PDMS) between the conductive material and the elastic substrate.…”