Effect of Porosity on Specific Resistance of Inkjet-Printed Silver Nanoparticles during Laser Sintering

Y.J. Moon, H. Kang, K. Kang, S.H. Lee, J.Y. Hwang, S.J. Moon
Korea Institue of Industrial Technology, KR

Keywords: porosity, specific resistance, inkjet printing, silver nanoparticles, laser sintering

Summary:

In nano-metal sintering, the electrical resistivity of nano-metals is related to their structure. Electrical resistivity is affected by grain size and density. Larger grains and denser films yield lower electrical resistivity. This work investigated the effect of porosity on specific resistance of silver nanoparticles with various laser intensities and irradiation durations. Conducting lines were printed on a glass substrate by a drop-on-demand (DOD) inkjet printer and silver nanoparticle ink. The conductivity and morphology of the laser sintered silver patterns were measured. Specific resistance did not decrease from 4 kW/cm2 laser intensity. Minimum specific resistance was 2.3 x 10-8 Ωm. When grain size exceeded the thickness of printed line, porosity began to increase. As laser intensity increase, pore and grain size increase. When grain size exceeded the thickness of printed line, laser sintered silver nanoparticles already had the specific resistance of Bulk silver. When printed line of the silver nanoparticles is sintered at very high laser intensity and for long irradiation time, specific resistance did not decrease any more due to the increase of porosity