The Numerical Simulation Of Stretchability Limit For Flexible Device

The emerging study for electronics field aims to develop stretchable, flexibleelectronics systerms, the strtechability of which depends on interconnects. The serpentineinterconnects consisting of arcs and lines can significantly improve the stretchability ofsysterm, which has wide application prospects. In this paper, to study the stretchability ofthin ineterconnects under prestrain substrate, take the serpentine interconnect structurefully abonded to substrate for example.Here, to yield significantly enhanced stretchability, the use of prestrain in thesubstrate is introduced, together with interconnects in narrow, serpentine shapes. Firstly,use abaqus nonlinear finite element soferware to establish3D models of film serpentineinterconnects-suabstrate systerm. Change the material and geometric parameters ofsubstrate with and without prestrain to investigate the relationship between elastic-stretch-ability and each parameter. The results show that: with the increasement of substratemodulus, the elastic stretchability of conductor decreases; the elastic stretchability isinsensitive to the variation in substrate thickness, for cases when the substrate is muchthicker than interconnect. The numerical results give quantitative description that thesubstrate prestrain can improve the stretchability significantly. The use of prestrain in thesubstrate and interconnects in serpentine shapes enhances the stretchability to more than100%.Secondly, change the material and geometric parameters with and without prestrain toinvestigate the relationship between elastic-stretchability and parameters; Establishbuckling analytical model and conclude the critical conditions of local and globle buckling,and the critical thickness of metal to occur buckling. The results show that: the elasticstretchability increases with the increasement of metal modulus; the elastic stretchabilityincreases with the length/spacing ration of interconnect for1and it saturatesfor1; in the case of substrate prestrain, the stretchbility increases slightly with theincreasement of thickness of interconnect, and then reach the maximum and it is insensitive to the variation in thickness of interconnect for the case of without presrtrain;the elastic stretchability, however, increases rapidly as the metal thickness decreases from2μm to0.25μm, and the stretchability exceeds100%for the case of t metal0.40μm; thelocal buckling mode occurs for t metal0.9μm.Finally, establish the crack propagation FEM of interconnect; optimize the serpentineinterconnect and establish the FEM of horseshoe interconnect with substrate prestrain. Thesimulation results indicate that the crack propagates when the concentrated strain exceedsfracture strain of interconnect; in the same circumstance, the stretchability of horseshoestructure is greater than the serpentine; the elastic stretchability is related to the andsubstrate modulus.The results have great significance in theoretical and practical research for the designof flexible electronics demanding great stretchability and high areal coverages, and havegreat potential applications in the field of photovoltaics, health monitoring and so on.