Effect of universal interconnect's geometrical parameters on metal-elastomer interface strength

Stretchable electronics can not only maintain the functional integrity of traditional planar and rigid devices, but also deform along with the sophisticated three-dimensional surface. Typical applications can be found in healthcare, biomedical implants and wearable functional clothes. In these systems, their stretchablity can be realized by means of designing different curved metallic wires embed in or on elastic substrate such as Polydimethylsiloxane (PDMS) or Polyurethance (PU). Rare hetero-interface delamination and rupture of conductors are expected during the practical usage. In this study the relationship between the geometrical shape of curved metallic wire and the interface strength is investigated using numerical simulation based on finite element analysis (FEA). Compared with other literature, the major difference is that a universal interconnect with four geometrical parameters of R (radius of arc), A (arc angle), T (oblique section of the curve) and H (horizontal section of the curve), which is not only a single one like serpentine shape or horseshoe shape etc., is analyzed. The main objective of this study is to discuss how the four parameters affect interface reliability. Design-of-experiment (DOE) methods and the finite-element modeling (FEM) are combined to schedule the simulation and obtain interface damage values. Based on the FEA results (interface damage values), the rank of the four factors in declining order to interface strength is given. Finally, a better combination is acquired to make the damage small when the applied strains are 30%. This study would provide a design guideline for building a rational curved structure to ensure reliable interface strength in stretchable systems.