Novel approach for integrating electronics into textiles at room temperature using a force-fit interconnection

Integration of electronics into textiles needs two connection steps. On the one hand, the mechanical connection to a textile material and on the other hand, the electrical connection to integrated conductive structures. Both connections have to be reliable. In the last ten years different technologies were used for this task. Almost all of them need a temperature step either for melting or curing. This work presents an alternative method that can be applied at room temperature. It is simple, fast, and cost-efficient. The conducted experiments analyze the force-dependent contact resistance between three different conductors and metal strip lines of different widths. As a result conductive yarns need much higher contact forces to gain low and stable contact resistances. This is due to their particular configuration and thin peripheral conductive layers. Wider strip lines will enhance their contact resistances. Cross-section analyses of loaded yarns together with the measured data allow for these interpretations. A design of a force-fit interconnection as well as a prototype is presented. Two plates are clamped to a piece of fabric with integrated conductive yarn. The developing elastic force is directed to the contact members. A final thermal cycling test between -40°C and +85°C for 1000 hours confirms the applicability of force-fit interconnections for smart textiles.