A copper-based ink contains copper acetate, 3-dimethylamino-1,2-propanediol and a silver salt. The ink may be coated on a substrate and decomposed on the substrate to form a conductive copper coating on the substrate. The ink provides micron-thick traces and may be screen printed and thermally sintered in the presence of up to about 500 ppm of oxygen or photo-sintered in air to produce highly conductive copper features. Sintered copper traces produced from the ink have improved air stability, and have improved sheet resistivity for 5-20 mil wide screen-printed lines with excellent resolution.