Photonic curing and soldering to printed silver for enhanced attachment and joint quality

Flexible hybrid electronics (FHE) have shown particular promise for novel fabrication techniques and architectures, often by involving low-temperature and low-cost flexible substrates, and additive manufacturing techniques. However, the challenge of interconnects for FHE devices, regularly reliant on conductive adhesives, remains significant because of the novel techniques and materials involved. One possible route to addressing this critical challenge is to consider new thermal processing methods for solder reflow beyond conventional ovens, near-infrared radiation heating, and even laser processing. This work demonstrates two applications of photonic processing for FHE device fabrication: curing conductive ink traces on temperature-sensitive substrates and subsequent component attachment using commercial solder paste. This study reports enhanced mechanical strength at the resulting solder joints and analyzes the mechanisms that produce this improvement. These results lay out a route to incorporate photonic processes for better FHE devices and packages.