Assessing the mechanical reliability of electrically shocked flexible interconnects

Silver nanoparticle interconnects inkjet-printed on polyethylene terephthalate (PET) substrates were investigated for electrical and mechanical reliability. Oven sintering at 100 °C reduced resistance by 25.9 ± 1.0% via nanoparticle coalescence. Durability was assessed under continuous DC voltage, repeated DC pulses during 4000-cycle bending fatigue, and moderately high voltage single transient 1.2/50 µs pulses. Under continuous DC, interconnects initially maintained low resistance. Repeated pulse testing at 4 V, 7 V, and 9 V showed voltage-dependent degradation: after 4000 cycles, resistance change was 0–2% at 9 V and 2–4% at 4 V, with higher voltages causing earlier failure. SEM imaging showed earlier crack initiation and faster propagation, along the grain boundaries. Transient pulses of 120–168 V caused abrupt resistance drops, sparking, and cathodic voids, causing failure within 3–4 pulses at ~148 V. Infrared imaging confirmed localized heating without bulk temperature rise (~1 °C). Comparative bending showed oven-sintered interconnects delayed fatigue onset and slowed crack evolution. Degradation during continuous DC was Joule heating–driven cracking, and during DC and transient pulsing, it was thermal shock.