A novel approach to improve reliability of aerosol jet printing process

Additive manufacturing is gaining interest for printing of noble metals. In this study, aerosol jet printing was applied to fabricate traces from commercial silver nanoparticle ink. A self -built three dimensional printing machine was used without or with in -line substrate heating. A conductive traces were printed on flexible polyimide substrates. Subsequently, sintering was conducted by furnace or near -infrared source. Examination of the sample using scanning electron and atomic force microscopy revealed the existence of both micro- and nanoscale pores in the structure. Local open porosity, aerosol extensive spatter and wide porous overspray were key defects found in samples printed without substrate heating. All the features affect the properties and reliability of silver prints. In -line process heating increased the concentration of nanoparticles and limited defects formation. What is more, the width of traces decreased from 31 gm to 19 gm with simultaneous thickness increase from 1.2 to 5.5 gm due to substrate heating. The final structure was influenced by sintering method and its time. Elongated time of sintering decreased porosity and roughness of the printed traces. Nevertheless, IR sintering provided the smoothest sample surface with lowest Sa roughness of 16 nm, and significantly improved bonding of aggregates. What is more, the printed structure had a measured sheet resistance of 8.3x10-2 omega/.