Deformable printed circuit boards that enable metamorphic electronics

A method to produce single-layer deformable and stretchable printed circuit boards is reported and applied to enable the realization of metamorphic electronic products that can take on new three-dimensional (3D) shapes. The models contain arrays with packaged surface mount devices and bare dies that integrate light-emitting diodes (LEDs) and transistors within a rubber matrix. The test structures morph from planar to spherical to cone-like topologies. In one approach, the thickness of the stretchable printed circuit board is locally adjusted to control the morphological changes. In addition, a three-dimensionally-shaped chaperon is introduced to enable more abrupt topological changes. A comparative study of various designs of the metallization layer and stress-relieving reinforcing elements identified a highly stretchable and deformable design (up to 315% or six thousand 150% stretch and release cycles), which shields the interface between the hard and non-stretchable components from high levels of stress. A slight tweak to normal fabrication procedures has enabled researchers develop circuit boards that turn into new three-dimensional shapes. Flexible electronic devices are usually made by depositing circuits onto rubberized substrates. But delaying the use of a stretchable support until the end of production makes it easier to design, test and process such materials, reports Heiko Jacobs from Technische Universität Ilmenau and colleagues. This approach enabled them to identify meandering metal ribbons and rigid reinforcement bars as ways to provide critical stress relief for ‘metamorphic’ electronics. After integrating light-emitting diodes and other surface-mounted devices into rubber matrices, the team transformed the flat materials into shapes such as spheres and cones by either adjusting the thickness of the rubber substrate or inflating them with the help of geometric ‘chaperones’. A novel approach to produce stretchable and deformable printed circuit boards is reported and applied to enable the realization of metamorphic electronic products, which conform to take on new three-dimensional shapes. The test structures morph from planar, to spherical, to cone-like topologies.