Arbitrarily shaped 2.5D circuits using stretchable interconnections and embedding in thermoplastic polymers

This contribution describes considerations and very preliminary results in the technology development of thermoplastically deformable electronics and sensor circuits, with the intention to eventually achieve the low-cost fabrication of 2.5D free-form rigid smart objects. The technology is based on the one for elastic circuits, developed and characterized before, which is using soft elastic polymers as materials for the circuit carrier. For 1-time deformable circuits the elastic carrier needs to be substituted by a thermoplastic material. An additional step of thermoforming is necessary after the entire circuit is fabricated on a flat surface, which is the normal industrial practice for circuit fabrication and which thus is also pursued here. First tests have been executed and simple circuits fabricated, using meandered Cu tracks as 1-time stretchable interconnects, PET-G as the thermoplastic carrier and SMD LEDs and zero-ohm resistors as circuit components. (C) 2014 The Authors. Published by Elsevier Ltd.