Characterization of Aerosol Jet Printed Silver Thin Films Sintered by a Scanning Laser

William A. Metzger, Wright State University


Direct write printing, which is part of additive manufacturing (AM) technology, offers unique capabilities that can complement traditional methods of electronics fabrication. Printing of electrical interconnects via aerosolization is one of the areas in AM that is very important in electronics fabrication. Post-print sintering is a critical step in printed electrical interconnects because it strongly influences the electrical resistivity of the interconnects. Interconnects require the lowest possible resistivity to achieve better performance. Thermal sintering is the most common technique employed in printed interconnects. However, it is limited to substrates that can handle the high temperature requirement for sintering. For polymers or other substrates with low thermal budget such as the ones used in wearable electronics, sintering becomes a challenge. In this work, we explored a scanning laser technique as an alternative to thermal sintering. In this study three separate ink materials (two from ElectronInks, and one from Novacentrix) were considered. First, optimal printing parameters such as sheath pressure, atomization pressure, and atomization current for each ink material were identified. Next, characterization of printed silvers sintered by different laser power conditions was performed to determine optimal sintering conditions. This characterization includes quantifying DC resistivity, temperature coefficient of resistance, surface morphology and porosity. Results from this work demonstrate some advantages of this sintering technique such as being able to selectively wash off un-sintered silver, which is attractive for fabricating strain sensors or other microelectronic applications.