Rigid and flexible printed circuit boards are carriers for electronic systems since decades. Recent developments enable the build-up of new types of electronic systems which can be attached on or integrated into three-dimensional surfaces with almost arbitrary shape. Moreover, these technologies not only reduce weight and volume in familiar applications through integration. By the shape adaptation entirely new functionalities and systemic changes emerge: previously “dumb” structures and surfaces containing integrated sensors, actuators and electronics give rise to novel interaction between the environment and the individual.
A key aspect of conformable electronics is the process flow. The term “conformable” indicates the primary focus on possibility to be shaped at some point in the process, as opposed to using a three-dimensional system carrier and fabrication process (the approach of MID technology). The design of conformable electronics draws on established two-dimensional processing technologies, used in the fabrication of printed circuit boards and (two dimensional) component assembly techniques established over recent decades. As such, conformable electronics are manufactured in the same way as conventional electronic systems. The advantages over rigid and flexible PCBs are only introduced in the final manufacturing step (forming).
At Fraunhofer IZM design rules, a full process chain using materials, which are compatible with PCB processing, and processes for the final forming are established. The manufacturing and product concepts include electronic systems on polymer based or textile circuit carriers that can extended by up to 50 %, thus allowing coverage of three-dimensional freeform surfaces without creasing. Apart from specially solid structured Cu traces, paste-printed interconnections are employed, depending on the use case. Currently, optimized forming processes are investigated to increase the degree of forming while improving control of local strain.