Stretchable electronic Systems for wearable and textile Applications

Assembly of electronic components on rigid and/or flexible printed circuit boards is today the customary way to fabricate electronic systems in stationary, mobile and automotive applications. On the other hand, many of the demands from emerging application fields like wearable and textile electronics cannot be met if with standard technologies. These fields have therefore become mayor drivers for the development of novel technologies. Among these 'stretchable electronics' have attracted much attention recently. Especially for textile applications the potential of the electronic system to comply with the body shape and movement will considerably improve the user comfort. In this paper we will present a cost effective technology for the realization of stretchable systems by common printed circuit board techniques like lamination, lithography, etching and micro via technology with polyurethane as a stretchable matrix/substrate material. Mastering of the adhesion between materials and the transitions region from stretchable to non-stretchable parts of the system are crucial for the mechanical performance and robustness. Technical approaches and the obtained results to tackle these issues will be presented. After a complete embedding of the components/interconnections the systems can be firmly attached to textile or non-woven cloth, which can be subsequently integrated into garments. The described process technology bears the potential for large scale roll to roll processing. Reliability aspects for stretchable electronic systems are so far not standardized and will be discussed briefly. Electrical and mechanical functionality of test vehicles subjected to multiple stretch and mild washing cycles will be presented. A functional electronic demonstrator with embedded passives, a micro controller, and LEDs which was realized with this technology will be shown.