In situ study of current-induced thermal expansion in printed conductors using stylus profilometry

• Published in: Flexible and printed electronics 2016-03, Vol.1 (1), p.12001
• Main Authors: Aga, Roberto S, Kreit, Eric B, Dooley, Steven R, Devlin, Christie L, Bartsch, Carrie M, Heckman, Emily M
• Format: Article
• Language: English
• Subjects: interconnects; power handling; printed electronics
• ISSN: 2058-8585; 2058-8585
• DOI: 10.1088/2058-8585/1/1/012001

An in situ technique that uses a stylus profilometer has been developed for studying current-induced thermal expansion in printed conductive traces and for investigating the effects of expansion on trace resistance and power handling. It was employed to study printed silver traces (50-100 m linewidths) subjected to a pulsed, millisecond-range current. The traces were aerosol jet printed on a glass substrate using a commercial nanoparticle-based ink. At low peak current densities (Jp < 5 × 104 A mm−2), trace expansion is reversible with no permanent resistance increase. At Jp ≥ 5 × 104 A mm−2 the expansion becomes irreversible, resulting in reduced power handling and a permanent resistance increase of up to 50%. Since the irreversible expansion decreases density and weakens nanoparticle connectivity, further expansion easily distends the material to the point of forming a void. This is one breakdown mechanism of printed nanoparticle-based silver at high pulsed current.