A Homogeneous Electrically Conductive Silver Paste

A homogeneous electrically conductive silver paste was developed using silver i-propylcarbamate ((CH₃)₂CHNHCOOAg) as the precursor of functional phase. The precursor had good solubility in water and methanol, high silver content (about 50 wt.%) and low decomposition temperature (below 200 °C). The paste was a non-Newtonian fluid with the viscosity depending significantly on the content of thickening agent (ethyl cellulose). When the paste was applied in micro-pen direct-writing process, it was able to produce high-resolution (20 μm or so) array patterns. After a homogeneous paste with about 40 wt.% silver i-propylcarbamate as the precursor was directly written and sintered at 180 °C for 15 min, an electrically conductive network consisting of more than 95 wt.% silver was formed and the network had a volume electrical resistivity in the order of magnitude of 10^-5-10^-6 Ω · cm and a sheet electrical resistivity in the order of magnitude of 10^-4 Ω/square.