Extreme Drop Durability of Sintered Silver Traces Printed With Extrusion and Aerosol Jet Processes

Sintered silver is a popular material for printing conductive traces in printed hybrid electronics (PHE). However, due to the novel materials and printing techniques in PHEs, reliability still needs to be adequately characterized for all types of life-cycle application conditions. This paper focuses on characterizing the reliability of printed silver traces fabricated with extrusion printing and aerosol jet printing (AJP) processes, under severe shock conditions up to 40,000 g peak acceleration, resulting in very high strain magnitudes and strain rates. This study utilizes test specimens of cantilever form factor to study the reliability of three-dimensional printed traces and substrates. Traces printed using both techniques were found to withstand repetitive drops at up to 40,000 g peak acceleration. However, extrusion-printed silver traces were found to be more reliable than their AJP counterparts, because of the extruded traces' superior adhesion to the FR4 substrate and lack of sintering shrinkage cracks. Strain gauges revealed strains in excess of 10,000 με during a 40,000 g shock event. A calibrated finite element (FE) model revealed that the strains at the trace location exceeded 15,000 με during a 40,000 g shock event.