An overbend strategy to manyfold enhance the designed elastic bendability of flexible electronics

Elastic bendability is crucial for flexible electronics to achieve conformal contact and enable widespread applications. However, reducing the thickness of the structure is almost the only strategy to enhance the elastic bendability of inorganic flexible electronics. This study proposes an overbend strategy, whose operation is beyond the designed elasticity of the fabricated structure. Mechanical theories, finite element analysis, and experiments verified that, with multilayer stacks and interconnects with various geometric designs as examples, the overbend strategy can enhance the designed elastic bendability to twice for the material of the ideal elastoplastic/kinematic hardening constitutive relationship and to more than twice for the mixed hardening/isotropic hardening constitutive relationship. The mechanism is extending the elastic strain range at the critical section to twice or more times the original value by the evolution of the elastoplastic constitutive relationship. Notably, the overbend strategy is virtually costless, combinative with other strategies and widely applicable for inorganic flexible electronics.